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1
Liu, Hong, Jiang Xin Feng, Ya Long Zhang, Yi Xing Yue, Tao Zhang, and Yu Pan. "Mechanism for Network Fracturing in Natural Fractured Reservoir." Advanced Materials Research 868 (December 2013): 718–24. http://dx.doi.org/10.4028/www.scientific.net/amr.868.718.
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By the methods of in-house experiment and theory analysis, the fracture initiation, stretch and interconnected mechanism of natural fracture is studied in the fracturing process of main fracture and branch fracture extending. The results have shown that, the hydraulic fracture in fractured formation is composed of a few main fractures in large size and many s secondary fractures in small size. The main fracture has the extending trend with the maximum crustal stress direction. The direction of sub fracture is network along the maximum crustal stress. The higher the degree of natural fractures, the difference between maximum and minimum crustal stress smaller. And the natural fracture is easier to form larger fracture. Fracture orientation and fracture width are determined by different combinations of natural fractures and the relative orientation with the maximum crustal stress.
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Boszczyk, Andrzej, and Stefan Rammelt. "Ankle fracture – correlation of Lauge-Hansen classification and patient reported fracture mechanism." Foot & Ankle Orthopaedics 3, no. 3 (July 1, 2018): 2473011418S0016. http://dx.doi.org/10.1177/2473011418s00165.
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Category: Trauma Introduction/Purpose: The genetic Lauge-Hansen classification is considered to provide a link between mechanism of ankle injury and resulting fracture morphology. In this study, we addressed the question of agreement between the mechanism of the fracture as postulated by the Lauge-Hansen classification and mechanism reported by the patient in rotational ankle fractures. Understanding of the actual mechanisms of ankle fracture may guide treatment decisions. Methods: Of 110 screened patients with acute malleolar fractures, 78 were able to provide information on their fracture mechanism and were included in the study. The study group consisted of 43 women and 35 men with a mean age of 47.8 (range 19.5-88.4) years. Patients were asked to describe the direction of deformation with primary question being pronation and supination as demonstrated by the examiner. As hyperplantarflexion and hyperdorsiflexion has been spontaneously reported by the patients, these directions were added to the analysis. Radiographs were analyzed according to Lauge-Hansen classification and compared with fracture mechanisms reported by the patients. Results: The majority (35/78 = 44.8%) of patients reported pronation as their fracture mechanism, 27 (34.6%) patients reported supination, 15 (19.2%) patients reported hyperplantarflexion (3 pure, one combined with pronation and 11 combined with supination), and 1 patient reported hyperdorsiflexion combined with pronation. Radiographs revealed 61 supination-external rotation (79%), 1 supination-adduction (1.3%), 14 pronation-external rotation (18%), 1 pronation-abduction (1.3%) fractures. One x-ray was unclassifiable with the Lauge-Hansen classification. The patient reported mechanisms were in concordance with the mechanism deducted from the x-rays in 49% of cases. Only 17% of patients who recalled a pronation trauma actually had radiographs classified as pronation fractures while 76% of patients who recalled a supination trauma were also radiographically classified as having sustained supination type fractures. Conclusion: The Lauge-Hansen classification should be used with caution for determining the actual mechanism of injury as it was able to predict the patient reported fracture mechanism in less than 50% of cases. A substantial percentage of fractures appearing radiographically as supination type injuries may have been actually produced by a pronation fracture mechanism.
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Baird, Alan F., J. Michael Kendall, and Doug A. Angus. "Frequency-dependent seismic anisotropy due to fractures: Fluid flow versus scattering." GEOPHYSICS 78, no. 2 (March 1, 2013): WA111—WA122. http://dx.doi.org/10.1190/geo2012-0288.1.
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Anisotropy is a useful attribute for the detection and characterization of aligned fracture sets in petroleum reservoirs. Unfortunately, many of the traditional effective medium theories for modeling the seismic properties of fractured rock are insensitive to the size of the constituent fractures. For example, the same pattern of anisotropy may be produced by a high concentration of small, stiff cracks or by a lower concentration of large, compliant fractures. The distinction between these models is important for assessing permeability anisotropy because fluid flow is dominated by the largest fractures. One method to gain further insight is through the analysis of frequency-dependent shear-wave splitting in microseismic data because fracture compliance is frequency dependent, and microseismic data are relatively rich in frequency content. We compared two potential mechanisms causing frequency-dependent compliance of fractures: (1) squirt flow in fractured porous rock and (2) wave scattering over rough fractures. Both models showed a sensitivity to average fracture size or compliance of the constituent fractures, and thus they provide a potential means to differentiate between anisotropy produced by small cracks or large fractures. We used both mechanisms to model frequency-dependent anisotropy data obtained from a fractured gas reservoir and invert for fracture parameters. Under certain conditions, the squirt-flow mechanism can cause significant frequency dependence in the microseismic band. However, the model is highly sensitive to the empirically derived mineral-scale relaxation time, which is poorly known and requires laboratory measurements to constrain. Conversely, producing a similar frequency response using the scattering model requires implausible fracture parameters; therefore, the squirt-flow model appears to be the most likely mechanism for microseismic applications. At higher frequencies, however, scattering may become more significant. Care should be taken when upscaling ultrasonic laboratory results for field-scale problems because different mechanisms may be at play within different frequency bands.
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Men, Xiao Xi, C. A. Tang, and Zhi Hui Han. "Numerical Simulation on Propagation Mechanism of Hydraulic Fracture in Fractured Rockmass." Applied Mechanics and Materials 488-489 (January 2014): 417–20. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.417.
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Hydraulic fracturing process in fractured rockmass which with an existing single natural fracture at its various conditions: its different angles and different lengths was simulated by using RFPA2D(2.0)-Flow version which adopts the finite element method and considers the heterogeneous characteristics of rock in meso-scale, creates seepage-stress-failure coupling model. The effect tendency of natural fractures angle and length on the seepage characteristics of fractured rockmass was given through the description of tensile fracture initiation and propagation in the rock specimens. The simulation results show that the effect of these two factors on fractures initiation, propagation and rockmass stability under the hydraulic fracturing could be remarkable.
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Yuan, Yingzhong, Wende Yan, Fengbo Chen, Jiqiang Li, Qianhua Xiao, and Xiaoliang Huang. "Numerical Simulation for Shale Gas Flow in Complex Fracture System of Fractured Horizontal Well." International Journal of Nonlinear Sciences and Numerical Simulation 19, no. 3-4 (June 26, 2018): 367–77. http://dx.doi.org/10.1515/ijnsns-2017-0135.
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AbstractComplex fracture systems including natural fractures and hydraulic fractures exist in shale gas reservoir with fractured horizontal well development. The flow of shale gas is a multi-scale flow process from microscopic nanometer pores to macroscopic large fractures. Due to the complexity of seepage mechanism and fracture parameters, it is difficult to realize fine numerical simulation for fractured horizontal wells in shale gas reservoirs. Mechanisms of adsorption–desorption on the surface of shale pores, slippage and Knudsen diffusion in the nanometer pores, Darcy and non-Darcy seepage in the matrix block and fractures are considered comprehensively in this paper. Through fine description of the complex fracture systems after horizontal well fracturing in shale gas reservoir, the problems of conventional corner point grids which are inflexible, directional, difficult to geometrically discretize arbitrarily oriented fractures are overcome. Discrete fracture network model based on unstructured perpendicular bisection grids is built in the numerical simulation. The results indicate that the discrete fracture network model can accurately describe fracture parameters including length, azimuth and density, and that the influences of fracture parameters on development effect of fractured horizontal well can be finely simulated. Cumulative production rate of shale gas is positively related to fracture half-length, fracture segments and fracture conductivity. When total fracture length is constant, fracturing effect is better if single fracture half-length or penetration ratio is relatively large and fracturing segments are moderate. Research results provide theoretical support for optimal design of fractured horizontal well in shale gas reservoir.
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Cheng, Hua, Xiangyang Liu, Jian Lin, Liangliang Zhang, Mingjing Li, and Chuanxin Rong. "Study on Fracturing and Diffusion Mechanism of Nonslab Fracturing Grouting." Geofluids 2020 (August 12, 2020): 1–9. http://dx.doi.org/10.1155/2020/8838135.
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The coupling effect of a slurry and the fractured rock layer controls a spatial attenuation of the fracture channel width and grouting pressure from a grouting hole to the slurry top of fracture diffusion. This paper comprehensively considers the influencing factors such as the mechanical properties of the injected rock mass and the time-varying characteristics of the serous viscosity and introduces the control equation of the fracture channel width to establish a single-fracture nonslab fracturing grouting model. Combining the motion law of the slurry with the extension form of fracture, the equation of slurry diffusion motion, considering the fracture geometry and the time-varying characteristics of the serous viscosity, is derived. Comparing this equation with the existing theories and experiments, the validity and reliability of the theory are verified. In this paper, the effects of rock elastic modulus, slurry viscosity, and grouting rate on the fracturing grouting diffusion law of rock mass are analyzed. It is pointed out that when fracturing grouting in deep rock layers, a larger initial grouting rate and grouting pressure should be selected in the early stages of grouting to generate or penetrate fractures in the rock layer. Also, when the grouting pressure is stable, it is appropriate to increase the viscosity so that the slurry can quickly gel in the fractures thus sealing the fractures.
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Ti, Zhengyi, Jiazhen Li, Meng Wang, Kang Wang, Zhupeng Jin, and Caiwang Tai. "Fracture Mechanism in Overlying Strata during Longwall Mining." Shock and Vibration 2021 (June 21, 2021): 1–15. http://dx.doi.org/10.1155/2021/4764732.
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We used the key stratum theory to establish a more realistic thin-plate mechanical model of elastic foundation clamped boundary and study the fracture mechanism of overlying strata during longwall mining. We analyzed the fracture characteristics and factors affecting fracture of the key stratum combined with the Mohr–Coulomb yield criterion. Besides, we used numerical simulation methods to verify the evolution pattern of the overlying strata fracture. The results show that the fracture mechanisms of the elastic foundation clamped structure’s key stratum varied depending on the position under longwall mining. The advanced coal wall area of the upper surface is a compressive-shear fracture. The center area of the lower surface is a tensile fracture. With the increase of the excavation length and the load of the key stratum, the central area and the advanced coal wall area of the long side are fractured before the advanced coal wall area of the short side. With the increase of flexural rigidity of the key stratum, the advanced coal wall area of the long side fractures before the central area and the advanced coal wall area of the short side. With the increase of the foundation modulus and the advanced load of the key stratum, the central area fractures before the surrounding advanced coal wall area. The advanced influence distance was positively correlated with the key stratum’s flexural rigidity and advanced load and negatively correlated with the foundation modulus and excavation length. The advanced influence distance was not affected by the load of the key stratum. The numerical simulation results show that, with the increase of the mining area, the fracture trace of overlying strata in goaf extended to the coal wall’s interior. The fracture range of overlying strata is larger than that of the miningd: area. This study has a practical value for water disasters, gas outbursts, and rock strata control.
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Li, Jianxiong, Shiming Dong, Wen Hua, Xiaolong Li, and Xin Pan. "Numerical Investigation of Hydraulic Fracture Propagation Based on Cohesive Zone Model in Naturally Fractured Formations." Processes 7, no. 1 (January 8, 2019): 28. http://dx.doi.org/10.3390/pr7010028.
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Complex propagation patterns of hydraulic fractures often play important roles in naturally fractured formations due to complex mechanisms. Therefore, understanding propagation patterns and the geometry of fractures is essential for hydraulic fracturing design. In this work, a seepage–stress–damage coupled model based on the finite pore pressure cohesive zone (PPCZ) method was developed to investigate hydraulic fracture propagation behavior in a naturally fractured reservoir. Compared with the traditional finite element method, the coupled model with global insertion cohesive elements realizes arbitrary propagation of fluid-driven fractures. Numerical simulations of multiple-cluster hydraulic fracturing were carried out to investigate the sensitivities of a multitude of parameters. The results reveal that stress interference from multiple-clusters is responsible for serious suppression and diversion of the fracture network. A lower stress difference benefits the fracture network and helps open natural fractures. By comparing the mechanism of fluid injection, the maximal fracture network can be achieved with various injection rates and viscosities at different fracturing stages. Cluster parameters, including the number of clusters and their spacing, were optimal, satisfying the requirement of creating a large fracture network. These results offer new insights into the propagation pattern of fluid driven fractures and should act as a guide for multiple-cluster hydraulic fracturing, which can help increase the hydraulic fracture volume in naturally fractured reservoirs.
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Wang, Shen, Huamin Li, and Dongyin Li. "Numerical Simulation of Hydraulic Fracture Propagation in Coal Seams with Discontinuous Natural Fracture Networks." Processes 6, no. 8 (August 1, 2018): 113. http://dx.doi.org/10.3390/pr6080113.
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To investigate the mechanism of hydraulic fracture propagation in coal seams with discontinuous natural fractures, an innovative finite element meshing scheme for modeling hydraulic fracturing was proposed. Hydraulic fracture propagation and interaction with discontinuous natural fracture networks in coal seams were modeled based on the cohesive element method. The hydraulic fracture network characteristics, the growth process of the secondary hydraulic fractures, the pore pressure distribution and the variation of bottomhole pressure were analyzed. The improved cohesive element method, which considers the leak-off and seepage behaviors of fracturing liquid, is capable of modeling hydraulic fracturing in naturally fractured formations. The results indicate that under high stress difference conditions, the hydraulic fracture network is spindle-shaped, and shows a multi-level branch structure. The ratio of secondary fracture total length to main fracture total length was 2.11~3.62, suggesting that the secondary fractures are an important part of the hydraulic fracture network in coal seams. In deep coal seams, the break pressure of discontinuous natural fractures mainly depends on the in-situ stress field and the direction of natural fractures. The mechanism of hydraulic fracture propagation in deep coal seams is significantly different from that in hard and tight rock layers.
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Jiang, Le, Peng Gao, Jie Liu, Yunbin Xiong, Jing Jiang, Ruizhong Jia, Zhongchao Li, and Pengcheng Liu. "Simulation and Optimization of Dynamic Fracture Parameters for an Inverted Square Nine-Spot Well Pattern in Tight Fractured Oil Reservoirs." Geofluids 2020 (September 22, 2020): 1–9. http://dx.doi.org/10.1155/2020/8883803.
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Dynamic fractures are a geological attribute of water flooding development in tight fractured oil reservoirs. However, previous studies have mainly focused on the opening mechanism of dynamic fractures and the influence of dynamic fractures on development. Few attempts have been made to investigate the optimization of the dynamic fracture parameter. In this study, the inverted square nine-spot well pattern model is established by taking fractured reservoir’s heterogeneity and its threshold pressure gradients into account. This simulation model optimizes the various parameters in a tight fractured oil reservoir with dynamic fractures, that is, the intersection angle between the dynamic fractures and the well array, the number of dynamic fractures, the penetration ratio, and the conductivity of the oil well’s hydraulic fractures. The results of this optimization are used to investigate the oil displacement mechanism of dynamic fractures and to discuss a mechanism to enhance oil recovery using an inverted square nine-spot well pattern. The simulation results indicate that a 45° intersection angle can effectively restrain the increase in the water cut. A single dynamic fracture can effectively control the displacement direction of the injected water and improve the oil displacement efficiency. Moreover, the optimal penetration ratio and the conductivity of the hydraulic fracture are 0.6 and 40 D-cm, respectively.
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Majed, Addie, Tanujan Thangarajah, Dominic FL Southgate, Peter Reilly, Anthony Bull, and Roger Emery. "The biomechanics of proximal humeral fractures: Injury mechanism and cortical morphology." Shoulder & Elbow 11, no. 4 (April 26, 2018): 247–55. http://dx.doi.org/10.1177/1758573218768535.
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Background The aim of this study was to examine the effect of arm position on proximal humerus fracture configuration and to determine whether cortical thinning would predispose to fracture propagation and more complex patterns of injury. Methods A drop test rig was designed to simulate falls onto an outstretched arm (‘parachute reflex’). Thirty-one cadaveric specimens underwent computer tomography scanning and cortical thicknesses mapping. Humeri were fractured according to one of the two injury mechanisms and filmed using a high-speed camera. Anatomical descriptions of the injuries were made. Areas of thinning were measured and correlated with zones of fracture propagation. Results Direct impact simulation resulted in undisplaced humeral head split fractures in 53% of cases, with the remainder involving disruption to the articular margin and valgus impaction. Alternatively, the ‘parachute reflex’ predominantly produced shield-type injuries (38%) and displaced greater tuberosity fractures (19%). A strong correlation was demonstrated between cortical thinning and the occurrence of fracture (odds ratio = 7.766, 95% confidence interval from 4.760 to 12.669, p<0.0001). Conclusion This study has shown that arm position during a fall influences fracture configuration of the proximal humerus. Correlating fracture pattern and mechanism of injury will allow more appropriate fracture reduction techniques to be devised.
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XU, PENG, HAICHENG LIU, AGUS PULUNG SASMITO, SHUXIA QIU, and CUIHONG LI. "EFFECTIVE PERMEABILITY OF FRACTURED POROUS MEDIA WITH FRACTAL DUAL-POROSITY MODEL." Fractals 25, no. 04 (July 25, 2017): 1740014. http://dx.doi.org/10.1142/s0218348x1740014x.
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As natural fractures show statistically fractal scaling laws, fractal geometry has been proposed and applied to model the fracture geometry and to study the hydraulic properties of fractured porous media. In this paper, a fractal dual-porosity model is developed to study the single-phase fluid flow through fractured porous media. An analytical expression for effective permeability of fractured porous media is derived, which depends on the fractal dimension and fracture aperture. The effect of fractal dimensions for fracture aperture distribution and tortuosity, the ratio of minimum to maximum fracture apertures and fracture fraction on the effective permeability have been discussed. In addition, a power law relationship between the effective permeability and fracture fraction is proposed to predict the equivalent hydraulic properties of fractured porous media. Compared with empirical formulas for effective permeability, the present fractal dual-porosity model can capture the statistical characteristics of fractures and shed light on the transport mechanism of fractured porous media.
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Xu, Tian Han, Yao Rong Feng, Sheng Yin Song, Zhi Hao Jin, and Dang Hui Wang. "Investigation of Fracture Mechanism of Casing-Drilling Steels." Advanced Materials Research 197-198 (February 2011): 1647–50. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.1647.
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The paper reports on an investigation of the fracture mechanism of both tensile and impact fracture in three types of casing-drilling steels. The results show that the tensile fracture surface of N80 steel includes fibrous zone, radiation area and shear lip zone, and those of both K55 and P110 steels include two zones; all the tensile fracture surfaces of three types of casing drilling steels show the ductile fracture mode, the ductile fracture mode indicated with dimples is observed on all zones; the impact fracture surface of the N80 steel possesses a combined quasi-cleavage and ductile fracture modes, a single fracture mode is observed on the fracture surface of both K55 and P110 steels, the K55 steel impact sample is fractured in a cleavage brittle manner, whereas the P110 steel impact sample is fractured in a dimpled ductile manner.
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Pollanen, M. S., J. H. N. Deck, B. Blenkinsop, and E. M. Farkas. "Fracture of Temporal Bone With Exsanguination: Pathology and Mechanism." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 19, no. 2 (May 1992): 196–200. http://dx.doi.org/10.1017/s0317167100042256.
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ABSTRACT:Eight cases of basal skull fracture with transverse fracture of the petrous temporal bone with medial extension to the internal carotid artery and lateral extension of the structures of the middle ear are described. Injuries in all cases were due to major blunt impact to the head usually occurring in a motor vehicle accident. General autopsy revealed major blood loss without any obvious external or internal site of hemorrhage suggesting that exsanguination was a complication of the head injury. The internal carotid arteries at the most medial extension of the fractures were lacerated or transected in all cases. In selected cases, the cervical internal carotid arteries were perfused and perfusate escaped rapidly from the ear(s) with the majority of fluid bypassing the cerebral venous system. Magnetic resonance image reconstruction of sequential sections of the fractured base of the skull confirmed the laceration of the internal carotid arteries and disruption of the middle ear. Based on this evidence, we propose that some displaced fractures of the base of the skull produce carotid-middle ear continuities which act as arterial shunts, resulting in rapid fatal exsanguination through the ear.
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Acosta Hospitaleche, Carolina, Leandro M. Perez, Walter Acosta, and Marcelo Reguero. "A traumatic fracture in a giant Eocene penguin from Antarctica." Antarctic Science 24, no. 6 (July 4, 2012): 619–24. http://dx.doi.org/10.1017/s0954102012000430.
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AbstractA fractured femur of a giant fossil penguin from the Anthropornis nordenskjoeldi Biozone (Late Eocene), Isla Marambio (Seymour Island), Antarctica (La Meseta Formation) is described. Palaeoecological, palaeopathological and taphonomical implications derived from the analysis of the kinds of fractures identified are also discussed. The main fracture has irregular margins, indicating there was collagen in the bone at the time of the impact. In this fracture, a mineral deposit was also identified as a fracture hematoma. According to the antemortem classification of fractures, it was produced by an indirect mechanism, provocating a “butterfly wing” or “third fragment” fracture. The remaining fractures are assigned to times of biostratinomic and fossil diagenesis.
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Bengtson, Hans, and Charles Giangarra. "Osteochondral Avulsion Fracture of the Anterior Cruciate Ligament Femoral Origin in a 10-Year-Old Child: A Case Report." Journal of Athletic Training 46, no. 4 (July 1, 2011): 451–55. http://dx.doi.org/10.4085/1062-6050-46.4.451.
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Objective: To describe the case of a 10-year-old football player who sustained a comminuted osteochondral avulsion fracture of the femoral origin of the anterior cruciate ligament (ACL) via a low-energy mechanism. Background: In children, both purely cartilaginous and osteochondral avulsion fractures have been described; most such ACL avulsions are from the tibial eminence. In the few previous case reports describing femoral osteochondral avulsion fractures, high-energy injury mechanisms were typically responsible and resulted in a single fracture fragment. Differential Diagnosis: Femoral osteochondral avulsion fracture at the ACL origin, femoral cartilaginous avulsion fracture at the ACL origin, midsubstance ACL tear, meniscal tear. Treatment: Sutures and a button were used to repair the comminuted fragments. Postoperatively, a modified ACL reconstruction rehabilitation program was instituted. Uniqueness: Most injuries of this nature in youngsters are caused by a high-energy mechanism of injury, result in an osteochondral avulsion fracture of the tibial eminence, and involve a single fracture fragment. Conclusions: Although they occur infrequently, ACL femoral avulsion fractures in children can result from a low-energy injury mechanism. Identifying the mechanism of injury, performing a thorough physical examination, and obtaining appropriate diagnostic studies will enable the correct treatment to be implemented, with the goal of safely returning the athlete to play.
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Sarkheil, Hamid, Hossein Hassani, and Firuz Alinia. "Fractured reservoir distribution characterization using folding mechanism analysis and patterns recognition in the Tabnak hydrocarbon reservoir anticline." Journal of Petroleum Exploration and Production Technology 11, no. 6 (June 2021): 2425–33. http://dx.doi.org/10.1007/s13202-021-01225-y.
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AbstractNaturally, fractured reservoirs play a considerable part in the study, production, and development of hydrocarbon fields because most hydrocarbon reservoirs in the Zagros Basin are naturally fractured. Production from those reservoirs is usually affected by the presence of a system of connected fractures. In this study, the Tabnak hydrocarbon field on the fold–thrust belt at the Zagros zone in the Persian plate has been analyzed by the facies models, folding mechanism analysis to identify fracture reservoir patterns. The results show a flexural fold with similarity in the folding mechanism and some open fracture potential made by limestone, shale, clay, and anhydrite in the study area's facies models. Consequently, the stress pattern and type of fracture issue on the fold's upper and lower layers will be similar. On the Tabnak anticline reservoir using image processing techniques in MATLAB R2019 software and kriging geostatistical methods, fracture surface patterns as a block model extended to the depth. Using the model results, fractures’ orientation distribution in adjacent wells 11, 14, and 15 is appropriate. The results also have similarities with the facies models, folding mechanism assessment, well test, and mud loss data analysis. These results can affect the development plans’ primary approach by drilling horizontal and sleep wells and hydrocarbon reservoir management strategies.
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Zheng, Yongxiang, Jianjun Liu, and Yun Lei. "The Propagation Behavior of Hydraulic Fracture in Rock Mass with Cemented Joints." Geofluids 2019 (June 27, 2019): 1–15. http://dx.doi.org/10.1155/2019/5406870.
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The formation of the fracture network in shale hydraulic fracturing is the key to the successful development of shale gas. In order to analyze the mechanism of hydraulic fracturing fracture propagation in cemented fractured formations, a numerical simulation about fracture behavior in cemented joints was conducted based firstly on the block discrete element. And the critical pressure of three fracture propagation modes under the intersection of hydraulic fracturing fracture and closed natural fracture is derived, and the parameter analysis is carried out by univariate analysis and the response surface method (RSM). The results show that at a low intersecting angle, hydraulic fractures will turn and move forward at the same time, forming intersecting fractures. At medium angles, the cracks only turn. At high angles, the crack will expand directly forward without turning. In conclusion, low-angle intersecting fractures are more likely to form complex fracture networks, followed by medium-angle intersecting fractures, and high-angle intersecting fractures have more difficulty in forming fracture networks. The research results have important theoretical guiding significance for the hydraulic fracturing design.
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Kobayashi, Ryoji. "Mechanism of Fracture." REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY 5, no. 2 (1996): 103–9. http://dx.doi.org/10.4131/jshpreview.5.103.
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Goldstuck, Norman D. "IUD fracture mechanism." Contraception 89, no. 4 (April 2014): 328. http://dx.doi.org/10.1016/j.contraception.2013.12.004.
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Galvan, Grace Naomi B. "Evaluation of Mandibular Fractures in a Tertiary Military Hospital: A 10-year Retrospective Study." Philippine Journal of Otolaryngology-Head and Neck Surgery 26, no. 1 (June 27, 2011): 16–20. http://dx.doi.org/10.32412/pjohns.v26i1.595.
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Objective: The study aimed to evaluate mandibular fractures in a tertiary military hospital, to determine the age group in which injury occurred most often, to examine the various mechanisms of injury, to determine the anatomical part of the mandible most frequently affected and to determine if there were significant relationships between the various mechanisms of injury and the different fracture sites.
Methods:
Design: Cross-sectional retrospective study
Setting: Tertiary Public Military Hospital
Patients: Medical records of 328 active military personnel and their dependents, treated for mandibular fracture at the Department of Otorhinolaryngology – Head and Neck Surgery, Armed Forces of the Philippines Medical Center from January 1999 – December 2009 were retrospectively reviewed for data regarding sex, age, various mechanisms of injury and fractured anatomical part of the mandible. The number of fractures per site according to mechanism of injury was tabulated and prevalence ratios (95% confidence intervals) and p values were computed for the different fracture sites among the various mechanisms of injury. The probability or risk of sustaining fractures in these sites based on mechanism of injury was then computed.
Results: The most fractured anatomical part of the mandible was the body (28%), followed by the parasymphysis (24%), angle (17%), symphysis (12%), ramus (8%), condyle (7%), alveolar ridge (3%) and coronoid (1%). There were associated injuries in 54% of those with mandibular fractures. In these patients, zygomaticomaxillary complex fractures occurred in 25%, head and neck abrasions and lacerations in 30%, head injuries in 28%, ocular injuries in 10%, nasal fractures in 8% and cervical spine fractures in 5%. Other injuries present were extremity trauma in 60%, thoracic trauma in 5% and abdominal trauma in 3%. Males dominated with a ratio of 99:1. Males 21 to 30 years of age sustained the most mandible fractures. Most fractures were caused by vehicular accidents (60%), followed by gunshot wounds (31%), falls (4%), violent assault (4%) and sports activities (1%). Alcohol was a contributing factor at the time of injury in 20.6% of fractures. All cases were treated by open reduction and internal fixation with plating or wiring.
Conclusion: The body was the most commonly fractured anatomic region of the mandible in this series. There appeared to be a statistically significant relationship between violent assault and fractures of the ramus, but not between the other mechanisms of injury and the site of fracture. Its prevalence ratio of 3.32 (95% confidence interval: 1.13; 9.74, p value 0.039) suggests that the prevalence of fractures of the ramus among those exposed to violent assault was 3 times higher than those who were not.
Keywords: mandibular fractures, etiology, maxillofacial injuries, trauma
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Wu, Feiran, Asim Rajpura, Mohammad Shahid, and Dilraj Sandher. "An Unrecognised Case of a Scapula Fracture Sustained through an Unusual Indirect Mechanism." Case Reports in Orthopedics 2013 (2013): 1–2. http://dx.doi.org/10.1155/2013/848953.
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Scapula fractures following low-velocity injuries are extremely rare but can be a missed associated fracture of other upper limb injuries. We describe the case of a patient who sustained a fracture of the scapula through an unusual and hitherto unreported indirect mechanism. The injury was associated with a radial head fracture and initially missed on presentation. This case highlights the need for increased vigilance when diagnosing injuries with unusual mechanisms.
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Zheng, Heng, Chunsheng Pu, and CHOE TONG IL. "Study on the Interaction Mechanism of Hydraulic Fracture and Natural Fracture in Shale Formation." Energies 12, no. 23 (November 25, 2019): 4477. http://dx.doi.org/10.3390/en12234477.
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Hydraulic fracturing is an essential technique for the development of shale gas, due to the low permeability in formation. Abundant natural fractures contained in a formation are indispensable for the development of a fracture network. In this paper, a damage-stress-seepage coupled hydraulic fracture expansion model, based on the extended finite element method, is established. The simulation results show that shear failure occurs when the hydraulic fracture interacts with a frictional natural fracture, while tensile failure occurs when it interacts with a cement natural fracture. Low interaction angles and high tensile strength of the rock are beneficial for the generation of a complex fracture network. Furthermore, under the same geological conditions and injection parameters, frictional natural fractures are more beneficial for the generation of a complex fracture network, when compared with cement natural fractures. This can not only effectively increase the propagation length of the natural fracture, but also effectively reduce its reactive resistance. This research is of great significance for the efficient exploitation of unconventional oil and gas resources.
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Song, Fuxian, Norm R. Warpinski, and M. Nafi Toksöz. "Full-waveform based microseismic source mechanism studies in the Barnett Shale: Linking microseismicity to reservoir geomechanics." GEOPHYSICS 79, no. 2 (March 1, 2014): KS13—KS30. http://dx.doi.org/10.1190/geo2013-0094.1.
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Seismic moment tensors (MTs) of microearthquakes contain important information on the reservoir and fracturing mechanisms. Difficulties arise when attempting to retrieve complete MT with conventional amplitude inversion methods if only one well is available. With the full-waveform approach, near-field information and nondirect waves (i.e., refracted/reflected waves) help stabilize the inversion and retrieve complete MT from the single-well data set. However, for events which are at far field from the monitoring well, a multiple-well data set is required. In this study, we perform the inversion with a dual-array data set from a hydrofracture stimulation in the Barnett Shale. Determining source mechanisms from the inverted MTs requires the use of a source model, which in this case is the tensile earthquake model. The source information derived includes the fault plane solution, slip direction, VP/VS ratio in the focal area and seismic moment. The primary challenge of extracting source parameters from MT is to distinguish the fracture plane from auxiliary plane. We analyze the microseismicity using geomechanical analysis to determine the fracture plane. Furthermore, we investigate the significance of non-DC components by F-test. We also study the influence of velocity model errors, event mislocations, and data noise using synthetic data. The results of source mechanism analysis are presented for the events with good signal-to-noise ratios and low condition numbers. Some events have fracture planes with similar orientations to natural fractures delineated by core analysis, suggesting reactivation of natural fractures. Other events occur as predominantly tensile events along the unperturbed maximum horizontal principal stress direction, indicating an opening mode failure on hydraulic fractures. Microseismic source mechanisms not only reveal important information about fracturing mechanisms, but also allow fracture characterization away from the wellbore, providing critical constraints for understanding fractured reservoirs.
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Cecil, Alexa, Jonathan W. Yu, Viviana A. Rodriguez, Adam Sima, Jesse Torbert, Jibanananda Satpathy, Paul Perdue, Clarence Toney, and Stephen Kates. "High- Versus Low-Energy Acetabular Fracture Outcomes in the Geriatric Population." Geriatric Orthopaedic Surgery & Rehabilitation 11 (January 1, 2020): 215145932093954. http://dx.doi.org/10.1177/2151459320939546.
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Introduction: High-energy mechanisms of acetabular fracture in the geriatric population are becoming increasingly common as older adults remain active later in life. This study compared outcomes for high- versus low-energy acetabular fractures in older adults. Materials and Methods: We studied outcomes of 22 older adults with acetabular fracture who were treated at a level-I trauma center over a 4-year period. Fourteen patients were categorized as low-energy mechanism of injury, and 8 were identified as a high-energy mechanism. We analyzed patient demographics with univariate logistic regressions performed to assess differences in high- and low-energy group as well as patient characteristics compared with surgical outcomes. Results: Most high-energy mechanisms were caused by motor vehicle collision (n = 4, 50.0%), with most having posterior wall fractures (50.0%). Among patient characteristics, the mechanism of injury, hip dislocation, fracture types, and fracture gap had the largest differences between energy groups effect size (ES: 2.45, 1.43, 1.36, and 0.83, respectively). The high-energy group was more likely to require surgery (odds ratio [OR] = 2.80, 95% CI: 0.26-30.70), develop heterotopic bone (OR = 4.33, 95% CI: 0.33-57.65), develop arthritis (OR = 3.60, 95% CI: 0.45-28.56), and had longer time to surgery (mean = 4.8 days, standard deviation [SD] = 5.8 days) compared to low-energy group (mean = 2.5 days, SD = 2.3 days). Discussion: The results of this case series confirm previous findings that patients with high-energy acetabular fractures are predominantly male, younger, and have fewer comorbidities than those who sustained low-energy fractures. Our results demonstrate that the majority of the high-energy fracture patients also suffered a concurrent hip dislocation with posterior wall fracture and experienced a longer time to surgery than the low-energy group. Conclusion: Geriatric patients who sustained high-energy acetabular fractures tend to have higher overall rates of complications, including infection, traumatic arthritis, and heterotopic bone formation when compared with patients with a low-energy fracture mechanism.
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Yin, Daiyin, and Wei Zhou. "Mechanism of Enhanced Oil Recovery for In-Depth Profile Control and Cyclic Waterflooding in Fractured Low-Permeability Reservoirs." Geofluids 2021 (April 20, 2021): 1–9. http://dx.doi.org/10.1155/2021/6615495.
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When fractured low-permeability reservoirs enter a high water cut period, injected water always flows along fractures, water cut speeds increase rapidly, and oil production decreases quickly in oil wells. It is difficult to further improve the oil recovery of such fractured low-permeability reservoirs. In this paper, based on the advantages of in-depth profile control and cyclic water injection, the feasibility of combining deep profile control with cyclic water injection to improve oil recovery in fractured low-permeability reservoirs during the high water cut stage was studied, and the mechanisms of in-depth profile control and cyclic waterflooding were investigated. According to the characteristics of reservoirs in Zone X, as well as the fracture features and evolution mechanisms of the well network, an outcrop plate fractured core model that considers fracture direction was developed, and core displacement experiments were carried out by using the HPAM/Cr3+ gel in-depth profile control system. The enhanced oil recovery of waterflooding, cyclic water injection, and in-depth profile control, as well as a combination of in-depth profile control and cyclic water injection, was investigated. Moreover, variations in the water cut degree, reserve recovery percentage, injection pressure, fracture and matrix pressure, and water saturation were monitored. On this basis, the mechanism of enhanced oil recovery based on the combined utilization of in-depth profile control and cyclic waterflooding methods was analyzed. The results show that in-depth profile control and cyclic water injection can be synchronized to further increase oil recovery. The recovery ratio under the combination of in-depth profile control and cyclic water injection was 1.9% higher than that under the in-depth profile control and 5.6% higher than that under cyclic water injection. The combination of in-depth profile control and cyclic water injection can increase the reservoir pressure; therefore, the fluctuation of pressure between the matrix and its fractures increases, more crude oil flows into the fracture, and the oil production increases.
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Ren, Qingshan, Yaodong Jiang, Pengpeng Wang, Guangjie Wu, and Nima Noraei Danesh. "Experimental and Numerical Simulation Study of Hydraulic Fracture Propagation during Coalbed Methane Development." Geofluids 2021 (August 17, 2021): 1–12. http://dx.doi.org/10.1155/2021/3632997.
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The extraction of low-permeability coalbed methane (CBM) has the dual significance of energy utilization and safe mining. Understanding hydraulic fracturing mechanism is vital to successful development of CBM. Therefore, it is important to improve the law of hydraulic fracture propagation in coal and rigorously study the influencing factors. In this paper, laboratory experiments and numerical simulation methods were used to investigate the hydraulic fracture propagation law of coal in coalbed methane reservoir with natural fractures. The results show that the maximum and minimum horizontal in situ stress and the difference in stress significantly affect the direction of crack propagation. The elastic modulus of coal, the mechanical properties of natural fractures, and the injection rate can affect the fracture length, fracture width, and the amount of fracturing fluid injected. To ensure the effectiveness of hydraulic fracturing, a reservoir environment with a certain horizontal stress difference under specific reservoir conditions can ensure the increase of fractured reservoir and the controllability of fracture expansion direction. In order to increase the volume of fractured reservoir and fracture length, the pumping speed of fracturing fluid should not be too high. The existence of stress shadow effect causes the hydraulic fracture to propagate along the main fracture track, where the branch fracture cannot extend too far. Complex fractures are the main hydraulic fracture typology in coalbed methane reservoir with natural fractures. The results can provide a benchmark for optimal design of hydraulic fracturing in coalbed methane reservoirs.
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Zhu, Wei Yao, Zhen Zhang, and Jia Deng. "Gas Flow Mechanism in Tight Reservoir and Productivity Prediction Model of Fractured Wells." Advanced Materials Research 868 (December 2013): 711–17. http://dx.doi.org/10.4028/www.scientific.net/amr.868.711.
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Flow mechanism in tight reservoir is different from that in normal reservoir because of the nanoscale and micro-scale holes in the reservoir. Beskok-Karniadakis model can describe gas diffusion and flow. In this paper, Beskok-Karniadakis model was applied and optimized in consideration of the tight gas productivity influenced by both Knudsen diffusion and desorption. Furthermore, tight gass productivity of fractured vertical wells was obtained with the method of permeability resistance. In combination of examples and theory, the influence of diffusion coefficient, half-length of fractures and fracture conductivity on well gas productivity was analyzed. The results show that free gas has a close connection with total productivity. Diffusion coefficients are not the same in different reservoir, and this can also influence the productivity. For fracture conductivity, the productivity goes up with the fracture conductivity increases. A method to provide guidance of effective productivity is gotten with optimizing the conductivity.
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IMATAMI, J., H. HASHIZUME, H. WAKE, Y. MORITO, and H. INOUE. "The Central Slip Attachment Fracture." Journal of Hand Surgery 22, no. 1 (February 1997): 107–9. http://dx.doi.org/10.1016/s0266-7681(97)80032-0.
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Eight displaced central slip attachment fractures were treated by open reduction and internal fixation to avoid boutonnière deformity, to reduce the fracture anatomically and to allow early mobilization of the joint. This injury should be recognized as a disruption of the dynamic extensor mechanism associated with an intraarticular fracture, fracture-dislocation or soft tissue injury of the PIP joint. We have grouped central slip attachment fractures into three types according to the mechanism of injury, with suggested methods of treatment.
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Reang, Santosh, Pulak Saha, and Tapan K. Das. "Bilateral patella fracture with unilateral refracture: a case report." International Journal of Research in Orthopaedics 7, no. 1 (December 23, 2020): 175. http://dx.doi.org/10.18203/issn.2455-4510.intjresorthop20205586.
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<p class="abstract">Patella fracture consists of approximately 1% of all skeletal fractures. However bilateral patella fracture is even rarer (2-3% of all patella fractures) and is seen mostly in either dash board injuries or in different pathological conditions. A 21 year old male presented with bilateral patella fracture, where right patella was fractured due to RTA and the left one got fractured due to a fall while he was being helped for an X-ray for the first one. Bilateral tension band wiring was done and patient was being regularly followed up with good range of movement recovery. But again he had a fall in bathroom 3 month post-operative and on right side suffered a re-fracture. Modified tension band wiring was done. Patient gained full range of movement on both sides and returned to his normal activities at 9 months post op of index surgery. A case of bilateral patella fracture where mechanism of fracture for each patella fracture are different is unheard of. A case of bilateral patella fracture with re-fracture has not been reported yet in literature so far we know/ searched. Here we report and discuss the challenges in management of such a case and protocol we followed.</p>
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Nandlal, Kiran, and Ruud Weijermars. "Impact on Drained Rock Volume (DRV) of Storativity and Enhanced Permeability in Naturally Fractured Reservoirs: Upscaled Field Case from Hydraulic Fracturing Test Site (HFTS), Wolfcamp Formation, Midland Basin, West Texas." Energies 12, no. 20 (October 11, 2019): 3852. http://dx.doi.org/10.3390/en12203852.
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Hydraulic fracturing for economic production from unconventional reservoirs is subject to many subsurface uncertainties. One such uncertainty is the impact of natural fractures in the vicinity of hydraulic fractures in the reservoir on flow and thus the actual drained rock volume (DRV). We delineate three fundamental processes by which natural fractures can impact flow. Two of these mechanisms are due to the possibility of natural fracture networks to possess (i) enhanced permeability and (ii) enhanced storativity. A systematic approach was used to model the effects of these two mechanisms on flow patterns and drained regions in the reservoir. A third mechanism by which natural fractures may impact reservoir flow is by the reactivation of natural fractures that become extensions of the hydraulic fracture network. The DRV for all three mechanisms can be modeled in flow simulations based on Complex Analysis Methods (CAM), which offer infinite resolution down to a micro-fracture scale, and is thus complementary to numerical simulation methods. In addition to synthetic models, reservoir and natural fracture data from the Hydraulic Fracturing Test Site (Wolfcamp Formation, Midland Basin) were used to determine the real-world impact of natural fractures on drainage patterns in the reservoir. The spatial location and variability in the DRV was more influenced by the natural fracture enhanced permeability than enhanced storativity (related to enhanced porosity). A Carman–Kozeny correlation was used to relate porosity and permeability in the natural fractures. Our study introduces a groundbreaking upscaling procedure for flows with a high number of natural fractures, by combining object-based and flow-based upscaling methods. A key insight is that channeling of flow through natural fractures left undrained areas in the matrix between the fractures. The flow models presented in this study can be implemented to make quick and informed decisions regarding where any undrained volume occurs, which can then be targeted for refracturing. With the method outlined in our study, one can determine the impact and influence of natural fracture sets on the actual drained volume and where the drainage is focused. The DRV analysis of naturally fractured reservoirs will help to better determine the optimum hydraulic fracture design and well spacing to achieve the most efficient recovery rates.
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Kelishadi, Shahrooz S., Matthew R. Zeiderman, Karan Chopra, Joseph A. Kelamis, Gerhard S. Mundinger, and Eduardo D. Rodriguez. "Facial Fracture Patterns Associated with Traumatic Optic Neuropathy." Craniomaxillofacial Trauma & Reconstruction 12, no. 1 (March 2019): 39–44. http://dx.doi.org/10.1055/s-0038-1641172.
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Traumatic optic neuropathy (TON) is rare. The heterogeneity of injury patterns and patient condition on presentation makes diagnosis difficult. Fracture patterns associated with TON have never been evaluated. Retrospective review of 42 patients diagnosed with TON at the R. Adams Cowley Shock Trauma Center from May 1998 to August 2010 was performed. Thirty-three patients met criteria for study inclusion of fracture patterns. Additional variables measured included patient demographics and mechanism. Cluster analysis was used to form homogenous groups of patients based on different fracture patterns. Fracture frequency was analyzed by group and study population. Visual depiction of fracture patterns was created for each group. Cluster analysis of fracture patterns yielded five common “groups” or fracture patterns among the study population. Group 1 ( n = 3, 9%) revealed contralateral lateral orbital wall (100%), zygoma (67%), and nasal bone (67%) fractures. Group 2 ( n = 7, 21%) demonstrated fractures of the frontal bone (86%), nasal bones (71%), and ipsilateral orbital roof (57%). Group 3 ( n = 14, 43%) involved fractures of the ipsilateral zygoma (100%), lateral orbital wall (29%), as well as frontal and nasal bones (21% each). Group 4 ( n = 5, 15%) consisted of mid- and upper-face fractures; 100% fractured the ipsilateral orbital floor, medial and lateral walls, maxilla, and zygoma; 80% fractured the orbital roof and bilateral zygoma. Group 5 ( n = 4, 12%) was characterized by fractures of the ipsilateral orbital floor, medial and lateral orbital walls (75% each), and orbital roof (50%). A notably high 15 of 33 patients (45%) sustained penetrating trauma. Our study demonstrates five fracture pattern groups associated with TON. Zygomatic, frontal, nasal, and orbital fractures were the most common. Fractures with a combination of frontal, nasal, and orbital fractures are particularly concerning and warrant close attention to the eye.
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Asadi, Mohammad Sadegh, and Vamegh Rasouli. "A laboratory fracture shear cell used for simulation of fracture reactivation." APPEA Journal 51, no. 1 (2011): 487. http://dx.doi.org/10.1071/aj10032.
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Fault reactivation is an unfavourable incident during drilling and production that may occur due to changes in situ stresses and reservoir pressure. Only a few studies, in their analyses, have included the effects of fault geometrical properties—these are important parameters controlling fault slippage and damage around it. In this paper, the significant influence of fracture morphology on the mechanical behaviour of rock fractures was investigated through experimental studies of shearing rock fractures in the lab. The experiments carried out using a fracture shear cell (FSC): the cell that was modified by adding a number of components to an existing true triaxial stress cell (TTSC) and designing a duplex high pressure cylinder that is capable of applying large normal stresses to the sample at a constant rate. A number of artificial blocks made of mortar material were subjected to shear tests using FSC under a wide range of normal stresses and at different shearing directions. The outputs of uniaxial compressive strength and fracture shear tests in the lab were used to plot the failure envelope of the fractured rock mass and discuss the failure mechanism through shearing. Accordingly, a calibrated, numerical discrete element method (DEM) was used to simulate the shear behaviour of fractures previously tested in the lab. The results of lab tests and DEM simulations will be presented and different failure mechanisms that are expected during shearing will be explained. The results show the significant influence of surface roughness on shear strength and extent of damage zone along the fracture. It was found that the shearing response of fractures depends on the magnitude of normal stress, which indicates the importance of having a good knowledge of in-situ stresses when modelling fault reactivation and damage near the fault zones. The results of lab experiments and numerical simulations were compared and good agreements were observed.
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Li, Jianxiong, Shiming Dong, Wen Hua, Yang Yang, and Xiaolong Li. "Numerical Simulation on Deflecting Hydraulic Fracture with Refracturing Using Extended Finite Element Method." Energies 12, no. 11 (May 28, 2019): 2044. http://dx.doi.org/10.3390/en12112044.
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Refracturing is a key technology in enhancing the conductivity of fractures from hydraulically-fractured wells. However, the deflecting mechanism of the diverting fracture is still unclear. In this paper, a fully coupled seepage-stress model based on the extended finite element method (XFEM) was developed to realize the deflection mechanism of the refracturing fractures. The modified construction of refracturing was then verified by laboratory experiments. Furthermore, two new deflection angles considering the influence area along initial fracture length were introduced to evaluate the refracturing. The numerical results demonstrated that: (1) lower stress difference, larger perforation angle and longer perforation depth can lead to a higher deflection angle, thereby a more curving propagation path of the diverting fracture; (2) increasing injection rate or fluid viscosity can significantly enhance the diverting behavior; and (3) an initial location near the root of the initial fracture results in a larger value of the deflection angle, which is preferred for far-field refracturing. The conclusions in this study can be a systematic guide for the parameter optimization in refracturing treatment.
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Papadakos, N., R. Pearce, and MD Bircher. "Low energy fractures of the acetabulum." Annals of The Royal College of Surgeons of England 96, no. 4 (May 2014): 297–301. http://dx.doi.org/10.1308/003588414x13814021680157.
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Introduction Acetabular fractures due to high energy injuries are common and well documented; those secondary to low energy mechanisms are less well described. We undertook a retrospective study of the acetabular fracture referrals to our unit to evaluate the proportion of injuries resulting from a low energy mechanism. Methods A total of 573 acetabular fractures were evaluated from 1 January 2005 to 31 December 2008. The plain radiography and computed tomography of those sustaining a low energy fracture were assessed and the fracture patterns classified. Results Of the 573 acetabular fractures, 71 (12.4%) were recorded as being a result of a low energy mechanism. The male-to-female ratio was 2.4:1 and the mean patient age was 67.0 years (standard deviation: 19.1 years). There was a significantly higher number of fractures (p<0.001) involving the anterior column (with or without a posterior hemitransverse component) than in a number of previously conducted large acetabular fracture studies. Conclusions Our results demonstrate that low energy fractures make up a considerable proportion of acetabular fractures with a distinctly different fracture pattern distribution. With the continued predicted rise in the incidence of osteoporosis, life expectancy and an aging population, it is likely that this type of fracture will become increasingly more common, posing difficult management decisions and leading to procedures that are technically more challenging.
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JOYCE, T. J. "Analysis of the Mechanism of Fracture of Silicone Metacarpophalangeal Prostheses." Journal of Hand Surgery (European Volume) 34, no. 1 (October 20, 2008): 18–24. http://dx.doi.org/10.1177/1753193408093808.
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Eleven fractured Sutter metacarpophalangeal prostheses were obtained from the hands of three patients. All of the implants had fractured at the junction of the distal stem and the hinge. After visual examination, the fracture faces were prepared and viewed using a scanning electron microscope. These images indicated that fracture was initiated by abrasion on the dorsal aspect of the distal stem of the prostheses, close to the hinge. Crack propagation was shown to be due to a fatigue process. Once a crack started, its direction of travel could be followed, using topographical features common to engineering fracture analyses. Propagation was from radial to ulnar and from dorsal to palmar.
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Xu, Lin Jing, Shi Cheng Zhang, and Jian Ye Mou. "Acid Leakoff Mechanism in Acid Fracturing of Naturally Fractured Carbonate Gas Reservoirs." Advanced Materials Research 868 (December 2013): 682–85. http://dx.doi.org/10.4028/www.scientific.net/amr.868.682.
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In acid fracturing, excessive acid leakoff is thought to be the main reason that limits fracture propagation and live acid penetration distance, so its very important to do research about acid leak-off on naturally fractured carbonates. we developed a new model in this paper to simulate acid leakoff into a naturally fractured carbonates gas reservoir during acid fracturing. Our model incorporates the acid-rock reaction on the fractured surfaces. Given the information of the Puguang gas reservoir, the model predicts acid filtration and leakoff rate over time. In this study, we found that acid leak-off mechanism in naturally fractured carbonates is much different from that in reservoirs without natural fractures. The leakoff volume is several times of nonreactive acid. Since the acid widened natural fractures, leakoff velocity increase with time firstly , then decrease. While the leakoff velocity of the nonreactive fluid decrease sustained. We also analyze other sensitivity parameters of the acid leakoff. In this model, we explain the acid leakoff mechanism in naturally fractured carbonates, and provide a more accurate calculating of fluid loss.
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Berry, M. D., D. W. Stearns, and M. Friedman. "THE DEVELOPMENT OF A FRACTURED RESERVOIR MODEL FOR THE PALM VALLEY GAS FIELD." APPEA Journal 36, no. 1 (1996): 82. http://dx.doi.org/10.1071/aj95005.
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A fractured reservoir model has been developed for the Palm Valley gas field, located WSW of Alice Springs, in the Amadeus Basin, NT. Definition of this complex, naturally fractured, Ordovician gas reservoir has required an integrated approach involving multiple studies to develop the geological model that has formed the basis for reservoir simulation and the rationale for the location of new wells. In addition, new seismic data provided fundamental input to the structure/fracture model of the field. Results suggest a primary, northsouth compression for the origin of structures in the basin and that Palm Valley resulted from a single, balanced folding phase. The seismic data show that Palm Valley is not an arcuate anticline as previously mapped, but is an elongate WSW to ENE trending, doubly plunging anticline with an offset crest and minor reverse faults at reservoir level. Investigations have shown that the majority of fractures in the reservoir outcrop are extremely ordered and there is definite structural control of the fracture spacing in the brittle reservoir rocks. Fracture trajectory and fracture intensity maps have been constructed, the latter providing the mechanism for distribution of fracture parameters around the field. The orientation of fractures measured at depth in the reservoir match exactly the fractures predicted from the structure/fracture model. This is the first time a fractured reservoir model that has been developed for Palm Valley, and it will form the basis for the further study and future development of the field.
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Shinya, Norio. "Creep fracture mechanism map." Bulletin of the Japan Institute of Metals 26, no. 8 (1987): 801–8. http://dx.doi.org/10.2320/materia1962.26.801.
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Chung, Moon Sang, Hee Joong Kim, Choong Hee Won, and Myung Chul Lee. "Mechanism of Scanhoid Fracture." Journal of the Korean Orthopaedic Association 25, no. 3 (1990): 747. http://dx.doi.org/10.4055/jkoa.1990.25.3.747.
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Li, Peilun, Yan Dong, Sheng Wang, and Peichao Li. "Numerical Modelling of Interaction between Hydraulic Fractures and Natural Fractures by Using the Extended Finite Element Method." Advances in Civil Engineering 2020 (September 21, 2020): 1–9. http://dx.doi.org/10.1155/2020/8848900.
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Natural fractures usually develop in shale reservoirs. Thereby, in the process of hydraulic fracturing, it is inevitable that hydraulic fractures will intersect with natural fractures. In order to reveal the interaction mechanism between hydraulic-induced fractures and natural fractures, a two-dimensional fracture intersection model based on the extended finite element method (XFEM) is proposed, and the different types of intersecting criteria reported in the literature are compared. Then, the effects of natural fracture azimuth, fluid pressure in hydraulic fracture, and in situ principal stress difference on hydraulic fracturing are studied in detail. The results show that the fracture morphology is different under different criteria and working conditions. And the stress concentration phenomenon mainly concentrates on the tip in the obtuse angle side of natural fracture. Meanwhile, different fluid pressures in hydraulic fracture can also induce different intersection patterns. The obtained results in this work are of great benefit to understand the intersection mechanism between hydraulic fractures and natural fractures.
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Kang, Zhengming, Xin Li, Weining Ni, Fei Li, and Xiao long Hao. "Using logging while drilling resistivity imaging data to quantitatively evaluate fracture aperture based on numerical simulation." Journal of Geophysics and Engineering 18, no. 3 (May 18, 2021): 317–27. http://dx.doi.org/10.1093/jge/gxab016.
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Abstract Fractured formations are strongly heterogenous, and thus exhibit a complex logging response mechanism. By using the logging while drilling (LWD) resistivity imaging tool, fractures can be visually identified and their aperture quantitatively calculated. Because physical fracture model simulation is time consuming and costly, we propose using a 3D finite element method (FEM) numerical simulation to interpret the LWD resistivity imaging tool logging responses in conjunction with a new aperture calculation model based on the forward model. First, we used the single fracture model to investigate the effect of fracture aperture and formation resistivity contrast on the maximum current contrast at the fracture. The results showed that the aperture is linearly related to the maximum current contrast, while the formation resistivity contrast exhibits a pronounced exponential relationship with the maximum current contrast. Both of these relationships are affected by the fracture's dip angle, so segmented fitting is required when the fracture dip angles differ. Next, using the forward model, we developed the fracture aperture calculation model based on the maximum current contrast. The aperture calculation model was established in three segments in accordance with the different fracture dips, and the influence factors affecting the fracture inverting inclination were analyzed using multi-fracture simulation images. Finally, the accuracy of the new model was verified with the simulated fracture images. The novel model for calculating fracture aperture is of great significance for processing and interpreting LWD resistivity imaging logging data.
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Khanna, Aditya, and Andrei Kotousov. "Controlling the Height of Multiple Hydraulic Fractures in Layered Media." SPE Journal 21, no. 01 (February 18, 2016): 256–63. http://dx.doi.org/10.2118/176017-pa.
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Summary Fracture-height containment is desirable in hydraulic-fracturing treatments because it can result in better efficiency of oil or gas recovery and have less impact on the environment. Several mechanisms of the containment of a single hydraulic fracture were investigated in the past, and the outcomes of these studies are now well-documented in the open literature. However, the effectiveness of these mechanisms in the case of multiple closely spaced hydraulic fractures has not received much attention. The latter situation typically arises in the case of multiple transverse fractures emanating from a single horizontal wellbore. In this paper, we develop a mathematical model that one can use to assess the fracture-interaction phenomenon as well as the effect of the modulus contrast between adjacent rock layers. We consider the situation in which one must contain the hydraulic fractures entirely in the pay zone and investigate fracturing-fluid-pressure control as a possible mechanism of height containment. It is demonstrated that when the fracture spacing becomes comparable with the fracture height, the interaction between the fractures produces a shielding effect. In this case, the fracturing-fluid pressure that ensures fracture containment is greater in comparison with the case of a single isolated fracture. However, the fracture opening is also smaller in the case of closely spaced fractures. The dependence of the fracturing-fluid pressure and fracture opening on the fracture spacing needs to be taken into consideration during the selection of fracture spacing for a particular treatment.
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Chen, Xuguang, Yuan Wang, Yu Mei, and Xin Zhang. "Numerical Simulation on Zonal Disintegration in Deep Surrounding Rock Mass." Scientific World Journal 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/379326.
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Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks.
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Landorf, KB. "Clarifying proximal diaphyseal fifth metatarsal fractures. The acute fracture versus the stress fracture." Journal of the American Podiatric Medical Association 89, no. 8 (August 1, 1999): 398–404. http://dx.doi.org/10.7547/87507315-89-8-398.
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This article discusses the classification and treatment of proximal diaphyseal fifth metatarsal fractures. There are two types of proximal diaphyseal fracture of the fifth metatarsal: the acute proximal diaphyseal fracture and the proximal diaphyseal stress fracture. Confusion between the two types of fractures is probably due to their similar location and the historical practice of referring to all fractures in this location as Jones fractures. Both fractures are prone to delayed union and require long periods of nonweightbearing immobilization or internal fixation for healing. However, because the mechanism of injury is different for each fracture, the treatment plan may need to be tailored to the particular type of fracture.
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Stevens, Jarrad M., Sarah Shiels, Michael R. Whitehouse, Anthony J. Ward, Tim J. Chesser, and Mehool Acharya. "Bilateral acetabular fractures: Mechanism, fracture patterns and associated injuries." Journal of Orthopaedics 18 (March 2020): 28–31. http://dx.doi.org/10.1016/j.jor.2019.10.012.
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Kremnev, Leonid, Vyacheslav Matyunin, Artem Marchenkov, and Larisa Vinogradova. "On the nature of steel fatigue fracture." International Journal of Computational Physics Series 1, no. 1 (March 1, 2018): 181–83. http://dx.doi.org/10.29167/a1i1p181-183.
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Experimental data confirmed that if steel cyclic stress reduces to less than tensile yield stress values, i.e., in case of high-cycle fatigue, the mechanism of fracture changes from dislocation to vacancy one. The authors based their findings on the fact that steel density determined by the method of liquid displacement is less than that of steel in both initial conditions and after fracture under the cyclic loads exceeding tensile yield stress values. In the latter case steel hardness increases, whereas the specimens fractured under the cyclic stresses less than their tensile yield stress values show no change in hardness. It means that in such a case metal fractures without strain hardening, i.e., undergoes brittle fracturing developing by vacancy mechanism rather than by dislocation one. As a result, such steel obtains the structure and properties similar to those appearing after its exposure to radiation, i.e., friability and brittleness.
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Song, Jing Wen, Ming Yu Wang, and Da Wei Tang. "Experiment on Water Infiltration and Solute Migration in Porous and Fractured Media." Advanced Materials Research 955-959 (June 2014): 1993–97. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1993.
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The experiments were performed by considering the upper loose porous media and lower fractured media as a typical structure of vadose zones, and by constructing the corresponding physical model to simulate water flow and solute transport processes in order to investigate water flow features and migration mechanism. It has been indicated that in the porous and fractured complex media, if the lower fracture structure remains unchanged, the structure and permeability of the porous media offer considerable impact on infiltration processes. Additionally, if the structure and permeability of the porous media remain unchanged, the overall permeability and flow features of the fracture structure are significantly controlled by fracture configurations. Furthermore, for the fracture structures with different fracture configurations, it is indicated that increasing of the density of the vertical fractures results in much more enhancement of the solute concentration decay rate than that caused by increasing the density of the horizontal ones. This investigation was expected to be of scientific significance and practical value for effective groundwater protection.
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Shao, Jiang, and Cheng Hui Zeng. "Research Progress on Fracture Mechanism of Mechanical Products." Advanced Materials Research 118-120 (June 2010): 551–55. http://dx.doi.org/10.4028/www.scientific.net/amr.118-120.551.
Full textAbstract:
Based on reliability physics theory, investigation on failure mechanism is a kernel job in reliability design and analysis of mechanical products. The basic conception and classification of failure mechanism are introduced. Researches on five kinds of fracture mechanisms (ductile fracture, cleavage fracture, quasi-cleavage fracture, fatigue fracture and intergranular fracture) are discussed in detail. At last, problems are summarized and suggestions for future investigations are also made.
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Xiang, Wang, and Xiao Hua Xue. "Mechanical Properties and Fracture Mechanism of TiCp/ZA-12 Composites." Key Engineering Materials 324-325 (November 2006): 671–74. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.671.
Full textAbstract:
TiCp/ZA-12 composites have been fabricated by XDTM method and stirring-casting techniques. The tests for mechanical properties reveal that the tensile strength and strength increase with increasing fraction of TiC particles. When the fraction of TiC particles increase up to 10%, the tensile strength and yield strength are 390MPa and 340MPa, respectively and they increase by 11% and 17% than that of matrix respectively. From the analysis of fractography we can see that mixed fracture of cleavage fracture and dimple fracture exists in the TiCp/ZA-12 composites, and fractured particles are not found. Finally the fracture model of composites has been established based on the experimental results.