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1
Ying, Hong-Wei, Kang Cheng, Li-Sha Zhang, Chang-Yu Ou, and Yong-Wen Yang. "Evaluation of excavation-induced movements through case histories in Hangzhou." Engineering Computations 37, no. 6 (2020): 1993–2016. http://dx.doi.org/10.1108/ec-06-2019-0256.
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Purpose Deep excavation in soft clay often causes additional deformations to surroundings. Then, if deformations cannot be predicted reasonably, the adjacent buildings may be threatened by the deep excavation. Based on the good field observations from ten deep excavations in Hangzhou, this paper aims to thoroughly investigate the characteristics of wall deflections and ground settlements induced by deep excavations. Design/methodology/approach On the basis of good field observation of ten deep excavations, the performances of excavations, supported by contiguous pile in Hangzhou, were studied, and also compared with other case histories. Findings The maximum wall deflections (dhm) rang mostly from 0.7 to 1.2 per cent He, where He is the final excavation depth, larger than those in Taipei and Shanghai. The observed maximum ground settlement in the Hangzhou cases generally ranges from 0.2 to 0.8 per cent He. Then, the settlement influence zone extends to a distance of 2.0-4.0 He from the excavation. The relatively large movements and influence zones in Hangzhou may be attributed to low stability numbers, large excavation widths and the creep effect. The excavation width is justified to have a significant influence on the wall deflection. Therefore, to establish a semi-empirical formula for predicting the maximum wall deflection, it is necessary to include the factor of excavation width. Originality/value The relevant literature concentrated on the characteristics of deep excavations supported by the contiguous pile wall in Hangzhou soft clay can rarely be found. Based on the ten deep excavations with good field observation in Hangzhou, the characteristics of wall deflection and ground settlements were comprehensively studied for the first time, which can provide some theoretical support for similar projects.
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Cao, Chengyong, Chenghua Shi, Linghui Liu, et al. "Novel Excavation and Construction Method for a Deep Shaft Excavation in Ultrathick Aquifers." Advances in Civil Engineering 2019 (September 30, 2019): 1–15. http://dx.doi.org/10.1155/2019/1827479.
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Dewatering using the dewatering systems composed of diaphragm walls and pumping wells is commonly adopted for deep excavations that are undertaken in deep aquifers. However, dewatering can sometimes induce environmental problems, especially when diaphragm walls cannot effectively cut off the aquifers. This paper mainly presents an innovative excavation technique combining dewatering excavation and underwater excavation without drainage, which is employed for a deep shaft excavation in ultrathick aquifers (up to 60–70 m thick aquifer) in Fuzhou, China. The shaft excavation with the depth of 41.6 m below the ground surface (BGS) is divided into two major phases, that is, (1) the first part of the excavation (the depth of 23.6 m BGS) is conducted by the way of conventional dewatering and braced excavation (Phase I) and (2) the second excavation with the depth of 23.6 m to 41.6 m BGS is carried out by the novel underwater excavation without drainage technique (Phase II). Field monitoring results show that the ratios of maximum ground surface settlement δvm to the excavation depth He in this case ranged from 0.03% to 0.1%. Most of the ratios of maximum lateral wall deflection δhm to excavation depth He are less than 0.1%. All these results are lesser than that predicted by empirical methods, which also confirmed the applicability of this innovative excavation. Thus, this innovative solution can be applicable to other deep excavations that are undertaken in ultrathick aquifers, especially for the excavation of coarse sediments with high permeability.
3
Liu, Guo B., Rebecca J. Jiang, Charles W. W. Ng, and Y. Hong. "Deformation characteristics of a 38 m deep excavation in soft clay." Canadian Geotechnical Journal 48, no. 12 (2011): 1817–28. http://dx.doi.org/10.1139/t11-075.
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To meet the increasing demand for underground space for economical development and infrastructural needs, more and more deep excavations have been constructed in Shanghai. In this paper, field performance of a 38 m deep multistrutted excavation in Shanghai soft clay is reported. The deep excavation was retained by a 65 m deep diaphragm wall. Inclinometers as well as settlement and heave markers were installed to monitor the performance of the deep excavation. This project provides an unusual opportunity to study the differential heaves of center columns and diaphragm walls during excavation. Because of the significant stress relief resulting from the 38 m deep excavation, maximum heaves of the center column and diaphragm wall panel were about 30 and 16 mm, respectively. The measured ratio δp/H (heave/final excavation depth) of column is less than 0.1% whereas the observed δp/H of the diaphragm wall panel is about 0.04%. The maximum distortion between the column and the diaphragm wall panel is smaller than 1/500, which is within the limit range proposed by Bjerrum in 1963. Owing to careful construction control, stiff strutting system, and compaction grouting, the measured lateral wall deflections and ground settlements at this site are generally smaller than other shallower excavations in soft clays in Shanghai, Singapore, and Taipei.
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Arabaninezhad, Arefeh, and Ali Fakher. "A framework for the use of reliability methods in deep urban excavations analysis." Acta Geotechnica Slovenica 18, no. 1 (2021): 2–14. http://dx.doi.org/10.18690/actageotechslov.18.1.2-14.2021.
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Deep excavations in urban areas impose deformation to adjacent structures; hence the reliability of deformation analysis for the real deep excavation projects is very important to be assessed. In this study a framework is presented for the use of reliability methods in deformation analysis of deep urban excavations. The suggested framework is applied for 5 real deep excavation projects implemented during last 10 years. All studied cases were recognized as projects of high importance in urban areas, and were monitored during the excavation process. A non-probabilistic reliability analysis procedure, Random set method, in combination with finite element numerical modeling is applied to obtain the probability of unsatisfactory performance for each case. The reliability analysis results are confirmed by field observations and measurements. Typical results for the probability of analytical deformations exceeding the acceptable values along with the site observations and measured displacements for 5 real deep excavation projects show that the reliability analysis could be a beneficial tool for designer. It is concluded that applying the suggested framework in the design stage of deep excavation projects may lead to design more appropriate systems compared to common deterministic design methods.
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Roboski, Jill, and Richard J. Finno. "Distributions of ground movements parallel to deep excavations in clay." Canadian Geotechnical Journal 43, no. 1 (2006): 43–58. http://dx.doi.org/10.1139/t05-091.
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An empirical procedure for fitting a complementary error function (erfc) to settlement and lateral ground movement data in a direction parallel to an excavation support wall is proposed based on extensive optical survey data obtained around a 12.8 m deep excavation in Chicago. The maximum ground movement and the height and length of an excavation wall define the erfc fitting function. The erfc fit is shown to apply to three other excavation projects where substantial ground movement data were reported.Key words: excavations, clays, ground movements, performance data.
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Wong, I. H., and T. S. Chua. "Ground movements due to pile driving in an excavation in soft soil." Canadian Geotechnical Journal 36, no. 1 (1999): 152–60. http://dx.doi.org/10.1139/t98-071.
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An excavation in soft clay for the construction of a deep basement frequently is accompanied by large ground movements that may damage piles preinstalled at the base of the excavation. In a recent project involving the construction of a 10 m wide, 3.7 m deep drain, the construction method adopted entailed excavating the site soils and then driving precast concrete piles. The excavation was supported by steel sheet piles braced by one level of struts. Large settlements and horizontal movements of the ground were observed during pile driving. These movements exceeded those occurring during the excavation phase. Concrete aprons outside a one-story building adjacent to the excavation were badly damaged during excavation and pile driving. However, the building supported on steel piles was undamaged.Key words: deep excavation, sheet piles, pile driving, ground movement, basement construction.
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Xu, Jianzhuang, Benli Sun, Ming Wu, and Haifeng Yang. "Deformation Assessment of Deep Excavations Retaining Structure in Collapsible Loess Areas." Journal of Physics: Conference Series 2424, no. 1 (2023): 012031. http://dx.doi.org/10.1088/1742-6596/2424/1/012031.
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Abstract In this study, the deformation characteristics of deep excavations retaining structure in loess areas are investigated statistically by analyzing filed measurements in three typical loess areas of Shaanxi, Shanxi, and Gansu. Generally, the study results showed that the maximum lateral displacement of the retaining structure ranges between 0.277‰H to 3.712‰H, with an average of 0.1029%H (H is the final excavation depth of excavations). The maximum lateral displacement is approximately located at 2/3 of the excavation depth. In addition, a quantitative analysis is carried out on the influencing factors for the lateral deformation of the retaining structure, such as the insertion ratio of retaining piles (walls), the length-wide ratio of the excavation plane, synthetical stiffness of the support system, heave-resistant safety factor, and the set depth of support in the first tunnel.
8
Ye, X. W., L. Ran, T. H. Yi, and X. B. Dong. "Intelligent Risk Assessment for Dewatering of Metro-Tunnel Deep Excavations." Mathematical Problems in Engineering 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/618979.
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In recent years, China has been undergoing a metro railway construction boom in order to alleviate the urban traffic congestion problem resulting from the rapid urbanization and population growth in many metropolises. In the construction of metro systems, deep excavations and continuous dewatering for construction of the metro tunnels and stations remain a challenging and high risk task in densely populated urban areas. Intelligent computational methods and techniques have exhibited the exceptional talent in dealing with the complicated problems inherent in the deep excavation and dewatering practice. In this paper, an intelligent risk assessment system for deep excavation dewatering is developed and has been applied in the project of Hangzhou Metro Line 1 which is the first metro line of the urban rapid rail transit system in Hangzhou, China. The specific characteristics and great challenges in deep excavation dewatering of the metro-tunnel airshaft of Hangzhou Metro Line 1 are addressed. A novel design method based on the coupled three-dimensional flow theory for dewatering of the deep excavation is introduced. The modularly designed system for excavation dewatering risk assessment is described, and the field observations in dewatering risk assessment of the airshaft excavation of Hangzhou Metro Line 1 are also presented.
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Feng, Shi Lun, Jie Liu, Jun Li, Pu Lin Li, and Yong Han. "The Bad Effects of Foundation Pit Heave on Foundation Piles." Advanced Materials Research 261-263 (May 2011): 1225–28. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1225.
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Deep excavations release stresses in the earth and redistribute these stresses causing deformation. The pressure loss due to excavation may result in a base instability, where the soil flow beneath the sheeting into the excavation, producing a rise in the base elevation commonly termed as heave. The heave can lead the foundation piles casted before excavation to floating and being in tension, and even induce the tensile failure of pile in severe case. The characters of foundation piles in different excavation conditions, different location have been analyzed by a case study. The calculation results show that the deeper excavation, the larger vertical force acted on the foundation pile and the heave could induce the tensile failure of the foundation piles. So it is recommended that the tensile capacity of the foundation piles should be verified when the excavation is very deep.
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Chen, Shong Loong, and Cheng Tao Ho. "Analysis on Deep Excavation in Soft Soil Located on Sloped Bedrock." Applied Mechanics and Materials 170-173 (May 2012): 13–19. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.13.
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Deep excavations in soft-clay layer on sloped bedrock often leads to lateral displacement on retaining structures and uneven settlement due to unbalanced pressure generated from excavation. A construction project for which an excavation was complete in soft clay layer on sloped bedrock in Taipei City was adopted in the study. It is learned from the observation logs of the studied case that a significant difference exists in the lateral displacement of diaphragm wall and settlement between up and down-slope sides of sloped bedrock. Deep excavation is in fact profoundly complicated interaction between excavation strutting and soil. In general practice, the design of excavation is frequently simplified as a 2D strain behavior. However, the actual excavation on sloped bedrock is quite different from 1D or 2D simulation in a symmetric manner. Therefore, 2D finite element analysis program, PLAXIS, is introduced for the analysis on the behaviors of soil clay layer on sloped bedrock in excavation. The result is compared with onsite observation data, including displacement of retaining wall, settlement, axial loads of struts and others. The result of retaining wall displacement analysis is found consistent with the trend derived from onsite observation, which is possible for reference of similar engineering analyses and designs in the future.
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Liu, Xiao Li, and H. Zhou. "Investigation on Behavior of Rock-Socketed Retaining Piles for Deep Excavation." Key Engineering Materials 462-463 (January 2011): 825–30. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.825.
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In the soil-rock mixed areas where the soils overlie on the rock layer, the rock-socketed retaining piles have been widely used for deep excavations. Up to date, little attention has been paid to performance of the rock-socketed piles used for deep excavation. Therefore, using the two-dimensional finite element program, Plaxis2D, a typical deep excavation engineering supported by rock-socketed piles with the whole embedded portion in rock is analyzed to investigate behavior of the rock-socketed retaining piles in detail. Computation results have shown that for rock-socketed retaining piles used in deep excavations, there exists an ultimate or a maximum rock-socketed depth which can be estimated by the pile diameter. For the ultimate rock-socketed depth, in the final excavation step, the first zero bending moment point of the rock-socketed part of the pile generally locates near the top surface of the rock layer. When the excavated surface is located at the top surface of the rock layer, the corresponding shear force distribution of the rock-socketed pile has an extremum at the same position.
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Mei, Yuan, Lu Wang, Dongbo Zhou, and Liaoyuan Fu. "Displacement Characteristics of a Deep Excavation in Hangzhou Soft Clay." Advances in Civil Engineering 2022 (March 16, 2022): 1–16. http://dx.doi.org/10.1155/2022/5469471.
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Excavations in a soft soil area are usually associated with substantial difficulties. Taking a special-shaped deep foundation pit in Hangzhou soft clay as the research object, the excavation performances, including groundwater level height, axial force, lateral wall, and soil deflection, and ground surface settlement were monitored and summarized based on the data published in the literature on similar excavations in Hangzhou, P. R. China. The following conclusions are drawn: (1) The axial forces of the struts dynamically change during the excavation and construction or removal of adjacent braces. (2) The ratio between the measured maximum wall deflection and excavation depth δ h − max / H e is 0.14–0.17%, larger than those in Shanghai. (3) The surface settlement behind the wall has an obvious primary influence zone and secondary influence zone, characterized by a “groove shape” and “triangle shape,” respectively. The maximum ground surface settlement δ v − max ranges from 0.29% to 0.5% of the excavation depth. (4) The distribution of the ground settlement was analyzed. The relationship between the maximum settlements δ v − max is between 1.28 δ h − max and 3.72 δ h − max . Moreover, ABAQUS software with Mohr–Coulomb soil models was used for model analysis of the construction process. The research results have important significance for the effective prevention of foundation pit accidents and the optimal design of deep foundation pit projects.
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Dong, Manman, and Pengjiao Jia. "Stability Analysis and Parameter Optimization of Deep Excavation Supporting System in Granular Soils." Advances in Civil Engineering 2020 (August 19, 2020): 1–10. http://dx.doi.org/10.1155/2020/8873655.
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Deep excavations are prone to result in excessive ground surface settlement displacement of surrounding existing structures, which could cause severe economic damage, even casualties. Hence, the optimization of pile parameters and evaluation of the stability of the excavation are of paramount importance. This paper aims to evaluate the security of deep excavation and optimize the parameters of supported piles in granular soils. An excavation case in granular soils is used to evaluate the stability of deep excavation using displacement least squares method. The stability of case history, Changqingqiao subway station, using pile and inner support system is evaluated by using the least square method. Subsequently, the finite element method is used to optimize the critical parameters of the supported piles, and it needs to be emphasized that the correctness and reasonability of the finite element (FE) models are evaluated according to field measurements. The optimum pile diameter and embedment ratio for single- and double-row retaining pile are 1.0 m and 0.4. The maximum vertical displacement of surrounding soil and horizontal displacement of piles can be calculated by the equations obtained in this research which can provide useful guidance for the designing of deep excavation.
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Guo, Panpan, Gang Lei, Lina Luo, et al. "Soil Creep Effect on Time-Dependent Deformation of Deep Braced Excavation." Advances in Materials Science and Engineering 2022 (January 10, 2022): 1–14. http://dx.doi.org/10.1155/2022/5655592.
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This paper describes recent advances in the effect of soil creep on the time-dependent deformation of deep braced excavation. The effect of soil creep is generally investigated using the observational method and the plain-strain numerical simulation method. The observational method is more applicable for deep braced excavations in soft clays constructed using the top-down method. The plain-strain numerical simulation method can be conveniently used for parametric analysis, but it is unable to capture the spatial characteristics of soil creep effect on lateral wall deflections and ground movements. The additional lateral wall deflections and ground movements that are generated due to the soil creep effect can account for as large as 30% of the total displacements, which highlights the importance of considering the effect of soil creep in deep braced excavations through soft clays. The magnitude of the displacements due to soil creep depends on various factors, such as excavation depth, elapsed period, unsupported length, and strut stiffness. Parametric analyses have indicated several effective measures that can be taken in practice to mitigate the detrimental effect of soil creep on the deformation of deep braced excavation. Based on the literature review, potential directions of the related future research work are discussed. This paper should be beneficial for both researchers and engineers focusing on mitigating the adverse effect of soil creep on the stability of deep braced excavations.
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Zheng, Yuchao, Jianyong Lei, Fei Wang, Liang Xiang, Jianfeng Yang, and Qingshuai Xue. "Investigation on Dewatering of a Deep Shaft in Strong Permeable Sandy Pebble Strata on the Bank of the Yellow River." Geofluids 2021 (September 24, 2021): 1–15. http://dx.doi.org/10.1155/2021/9994477.
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This paper reports the dewatering scheme of a deep excavation in sandy pebble strata. The excavation is in high permeability strata and is close to the Yellow River, making the dewatering difficult during construction. At present, few researchers have specially studied the dewatering scheme of deep excavations in strong permeable strata near the water resource. Field pumping test was conducted before the excavation activity, and the permeability coefficient of the strata was obtained by reverse analysis. According to the characteristics of the project, the dewatering scheme of “ waterproof curtain + base grouting + pumping ” was proposed. The influence of vertical waterproof curtain and base grouting on dewatering was analyzed by numerical simulation. In the construction process, the field water table and ground settlement were measured. The results show that (1) the groundwater table versus permeability coefficient curve shows three different stages and (2) the dewatering scheme of “ waterproof curtain + base grouting + pumping ” is effective for deep excavation in strong permeable strata.
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Ozocak, Aşkın, Sedat Sert, and Ertan Bol. "Alüviyal Ortamda Derin Kazı Problemi." Academic Perspective Procedia 2, no. 3 (2019): 1369–76. http://dx.doi.org/10.33793/acperpro.02.03.152.
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The basement needs that emerged in the city centers have led to a more frequent encounter with deep excavation problems, which is one of the important issues of Geotechnical Engineering. This situation requires additional care and experience for soil and rock environments especially in deep excavations where different shear resistance parameters can be mobilized both in the short term and in the long term. In this paper, the stages of soil investigation, analysis, manufacturing and measured deformation were evaluated within the scope of the deep excavation planned and carried out in Adapazari city center. Following the excavation and filling phase at a depth of 4 m following the construction of the secant piles, the deformation readings were particularly noticeable on the eastern border. SAU Geotechnical Working Group conducted an investigation study to understand the causes of the incident and to take the necessary measures, if any. After the investigation, the reason of the deformations was estimated to be due to the sudden drainage of groundwater during the construction of the piles, and subsequent consolidation of the clayey layers beneath the existing 5-storey structure adjacent to it. The excavation has been successfully completed with the projected horizontal support system and it has been observed that the application of strut in the deep excavation support system creates practical difficulties especially in small parcels during the excavation phase.
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Liang, Yao-Ying, Nian-Wu Liu, Feng Yu, Xiao-Nan Gong, and Yi-Tian Chen. "Prediction of Response of Existing Building Piles to Adjacent Deep Excavation in Soft Clay." Advances in Civil Engineering 2019 (December 5, 2019): 1–11. http://dx.doi.org/10.1155/2019/8914708.
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This study investigates building settlements near excavations in soft clay. A simplified theoretical method is proposed to predict the additional settlements and axial forces of excavation-adjacent existing building floating piles in soft clay. The soil displacement is simplified as a line or broken line along the depth direction, depending on the distance from the excavation. A hyperbolic model is applied to calculate the skin friction and tip resistance induced by the vertical soil displacement. The parameters of the hyperbolic model are corrected to fit data from in-service piles. Based on the load-transfer curve method, the additional settlements and axial forces are determined. The measured data of 17 floating piles from two excavation cases in Hangzhou, China, show good agreement with the calculated values. The results show that the position of the neutral point of the loaded pile varies with the soil settlement. Because of the upper structure, the theoretical settlements for piles near the excavation are larger than those obtained from the measured values; for distant piles, this relationship is reversed. The proposed prediction methodology is expected to guide the design of practical excavations.
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Yang, Zi Sheng, Jun Xia Liu, and Yi Ren Wang. "Weight Analysis of Accident Factors in Deep Foundation Excavation Based on Analytic Hierarchy Process." Applied Mechanics and Materials 711 (December 2014): 529–34. http://dx.doi.org/10.4028/www.scientific.net/amm.711.529.
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For the past few years, great development has been achieved in deep foundation excavation. However, due to foundation excavation’s locality, individual diversity, complexity and uncertainty, the probability of accidents in foundation pit engineering tends to be greater than that in main works, and the accident rate may even reach about 20%, which makes the study on factors leading to foundation excavation accidents quite necessary and meaningful. By use of Analytic Hierarchy Process (AHP), this paper has figured out the ratio (weight) of the investigation, design, construction and other factors leading to foundation excavation accidents to the whole factor set, which is of great guiding significance to the study on prevention and treatment of foundation excavation accidents in future.
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Wang, Zhong W., Charles WW Ng, and Guo B. Liu. "Characteristics of wall deflections and ground surface settlements in Shanghai." Canadian Geotechnical Journal 42, no. 5 (2005): 1243–54. http://dx.doi.org/10.1139/t05-056.
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The characteristics of wall deflections and surface ground settlements at six deep multi-strutted excavations in Shanghai soft soils were studied and compared with those of similar case histories reported worldwide, particularly in Taipei and Singapore. The measured wall deflections at the six metro stations of the Pearl II Circle Line show a typical bulging profile (or deep-seated shape) at the end of the excavation. The ratio between the measured maximum wall deflection and the depth of the excavation (δhm /H) in Shanghai was <0.007, which was similar to the ratio measured in Taipei, but it was substantially smaller than the Peck bounding limit of 0.01. At each station, the measured maximum displacement was <0.45% of the final excavation depth. Because of the large aspect ratios of the underground excavations, no significant three-dimensional effects or corner effects were observed. The measured maximum settlements of the six metro excavations fell within zone I of the Peck classical normalized settlement-distance chart. These small measured settlements were consistent with the small measured wall deflections. The observed relatively small maximum wall deflections can likely be attributed to the use of prestressed struts, the constant adjustment of the stresses to about 0.7 times the total vertical stress during the excavation, and the short horizontal span of the excavation.Key words: multi-strutted excavations, soft clay, Shanghai, metro stations, horizontal deflection, settlement.
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Mekdash, Hani, Lina Jaber, Yehya Temsah, and Marwan Sadek. "Reinforcement of Concrete Shoring Systems by Prestressing." Advances in Civil Engineering 2022 (September 23, 2022): 1–10. http://dx.doi.org/10.1155/2022/2383781.
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Reinforced concrete piles are useful structural elements to support deep excavations. A pile wall is usually supported by one or several rows of anchors, depending on the depth of the excavation and the nature of the soil retained. The purpose of this work is to investigate the efficacy of posttensioned piles in retaining a 10.0 m deep excavation without using tieback anchors. In addition to the conventional passive steel reinforcement, the piles in this system include steel strands placed eccentrically in their sections, and they are referred to as posttensioned piles. The performance of posttensioned piles is investigated using the finite element modeling software PLAXIS 2D. The results are experimentally validated on a large-scale construction site. The horizontal displacement of posttensioned piles in a 10 m deep excavation was found to be within allowable limits with a 7.36% difference in the horizontal displacement of pile top at the final excavation level in PLAXIS 2D. In terms of cost, PTP is executed at 35% cost less than the conventional reinforced method.
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Gestrich, Nikolas, and Kevin C. MacDonald. "On the Margins of Ghana and Kawkaw: Four Seasons of Excavation at Tongo Maaré Diabal (AD 500-1150), Mali." Journal of African Archaeology 16, no. 1 (2018): 1–30. http://dx.doi.org/10.1163/21915784-20180001.
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AbstractThis article summarises the results of four seasons of excavation at Tongo Maaré Diabal (AD500-1150), near Douentza, Mali. Deep stratigraphic excavations were directed by MacDonald and Togola in 1993, 1995 and by MacDonald in 1996. Complementary, large exposure excavations of the abandonment layer were undertaken by Gestrich in 2010. The combined excavation results speak to topics of craft specialisation, trade, and social organisation. They provide evidence of a specialised blacksmithing community situated at the margins of early Middle Niger and Niger Bend statehood and urbanisation.
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Cui, Jifei, Zhenkun Yang, and Rafig Azzam. "Field Measurement and Numerical Study on the Effects of Under-Excavation and Over-Excavation on Ultra-Deep Foundation Pit in Coastal Area." Journal of Marine Science and Engineering 11, no. 1 (2023): 219. http://dx.doi.org/10.3390/jmse11010219.
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An ultra-deep L-shape foundation pit in a coastal area has recently been constructed and monitored. The project overview, geological conditions, excavation sequence and monitoring scheme are introduced in detail. The deformation of the retaining structure and surrounding strata are analyzed in detail through the measured data and 3D numerical simulation. The results show that the exceptional performance of the current project is due to the combination of under-excavation and over-excavation during construction. The under-excavation procedure restrained the wall deflections at the middle part of the diaphragm wall, making the corner effects at the corresponding side inapparent. Both the under-excavation and over-excavation procedure can only influence the performance of the excavation in close proximity, while having negligible impacts on the normally excavated areas. Based on the results of this study, practical suggestions are given to improve the performance of similar excavations in the future.
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Li, Xian, Tingguo Zhou, Yixian Wang, et al. "Response Analysis of Deep Foundation Excavation and Dewatering on Surface Settlements." Advances in Civil Engineering 2020 (November 10, 2020): 1–10. http://dx.doi.org/10.1155/2020/8855839.
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Accurate prediction of surface settlements is a primary concern when deep excavations were carrying out under the water table in urban environments for the safety of the work site. The sedimentation deformation due to deep excavation of foundation pit and dewatering occurs as a result of coupling action of the two factors. The study is aimed at revealing the coupling ground response to the two factors and developing empirical correlations for estimating ground deformations. Taking a deep foundation pit of a metro station as an example, surface settlement estimations were calculated by analytical formulas and numerical models. The settlement results by analytical formulas under excavation and dewatering conditions were added linearly to the total settlements. And three-dimensional coupling numerical models were established by applying commercial software (GMS and MIDAS) to investigate the interaction impact of excavation and dewatering on the sedimentation deformation. Comparing with monitoring data, numerical simulation results match well with the monitoring data. Furthermore, an empirical surface subsidence correlation equation was developed by the polynomial fitting to illustrate the effect contribution on the total surface settlement of foundation excavation and dewatering.
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Maher T. El-Nimr, Ali M. Basha, Mohamed M. Abo-Raya, and Mohamed H. Zakaria. "General deformation behavior of deep excavation support systems: A review." Global Journal of Engineering and Technology Advances 10, no. 1 (2022): 039–57. http://dx.doi.org/10.30574/gjeta.2022.10.1.0181.
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In geotechnical engineering, ground movement caused by excavations is a challenging issue. The excessive differential settlement generated by soil movement induced by wall deflection may cause damage to nearby structures. A detailed literature review on the general deformation behavior of deep excavation support systems is presented in this paper. Many factors, such as normalized horizontal deflection (δh-max/He%), vertical displacement (δv-max/He%), δvmax/δhmax ratio, settlement influence zone (Do), etc., can play significant roles in describing the deflection behavior of the excavation system. A descriptive analysis of the reviewed data was carried out. The concluded δh-max/He% values range between 0.17 to 1.5, with a mean value of 0.58 for soft clay, while in the case of sands and stiff clay soils δh-max/He% value ranges between 0.07 to 0.40, with a mean value of 0.20. δv-max/He% values range between 0.13 to 1.10, with a mean value of 0.49 for soft soil, while its value ranges between 0.02 to 1.10, with a mean value of 0.24 in the case of sands and stiff clay soils. The settlement influence zone (Do) reaches a mean distance of 2.3He, which falls within Do=1.5-3.5He in the case of soft clays, while Do reaches a mean distance of 2.0He and 3.0He in the case of sands and other stiff clay soils, respectively. The relationship between system stiffness and excavation-induced wall and ground movements was discussed. Unfortunately, the literature review offers limited data regarding system stiffness, the 3-D nature of excavation support systems, excavation processes, and time effects.
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Fujita, Keiichi. "Deep Excavation in Soft Ground." Doboku Gakkai Ronbunshu, no. 499 (1994): 1–12. http://dx.doi.org/10.2208/jscej.1994.499_1.
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Shoari Shoar, S. Mohammad, Ali A. Heshmati, and Hossein Salehzadeh. "Prefailure Deformation of Nailed Deep Excavations under Surcharge by Centrifuge Model Test." Advances in Civil Engineering 2021 (August 25, 2021): 1–13. http://dx.doi.org/10.1155/2021/5569797.
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To study prefailure deformations in nailed deep vertical excavations under various surcharges, four centrifuge tests were used to explain the lateral deformation of facing, the fracture mechanism of cement facing, and the settlement profile of the ground surface. The soil used in this research was Firoozkooh sand No. 161. Both surcharge applying and excavation were performed at 40 g acceleration. The depth of the excavation was 30 cm, the length of the nail varied from H/3 to 2H/3 (H: excavation depth), and the nails were installed horizontally. The nails were made of brass pipes and then sand coated. The results showed that the effect of surcharge on the lateral deformation of the facing as well as the fracture mechanism of facing is obvious. Also, it was seen that the ground settlement profile is two-line or three-line at the moment of facing fracture and is affected by surcharge.
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Li, Biao, Feng Dai, Nu Wen Xu, and Chun Sha. "Establishment and Application of Microseismic Monitoring System to Deep-Buried Underground Powerhouse." Advanced Materials Research 838-841 (November 2013): 889–93. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.889.
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The right bank underground powerhouse of Houziyan hydropower station is a typical deep-buried type with high geostress and complicated geological conditions. To monitor and analyze the stability of surrounding rock mass during continuous excavation of the powerhouse excavation and locate the potential failure zones, an ESG (Engineering Seismology Group) microseismic monitoring system manufactured in Canada was installed in April, 2013. The wave velocity of the monitoring system was determined through fixed blasting tests. And the average location error is the minimum while P-wave velocity is 5700m/s, less than 10m and meeting the system request. By combining the temporal and spatial distribution regularity of microseimic events with field excavation, micro-crack clusters and potential instability zones were identified and delineated. The results will provide a reference for later excavations and supports of the underground powerhouse. Furthermore, a new monitoring method can also be supplied for the stability analysis of surrounding rock mass in deep-buried underground powerhouses.
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Rotisciani, G. M., S. Miliziano, and S. Sacconi. "Design, construction, and monitoring of a building with deep basements in Rome." Canadian Geotechnical Journal 53, no. 2 (2016): 210–24. http://dx.doi.org/10.1139/cgj-2015-0244.
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In this paper, excavations for the construction of a tall building with deep basements in a congested area in Rome, close to the Tiber river are described. The project was technically challenging due to the close proximity of existing buildings, the interaction with the river, and the poor geotechnical properties of the alluvial deposits. This well-documented case study addresses the geotechnical and structural issues involved in the development of the design and construction process. Particular attention is focused on the prediction of excavation-induced displacements and on the efficiency of the water wells introduced to increase safety margins against the hydraulic uplift of the excavation bottom.
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Chen, Shangrong, Jifei Cui, and Fayun Liang. "Case Study on the Deformation Coupling Effect of a Deep Foundation Pit Group in a Coastal Soft Soil Area." Applied Sciences 12, no. 12 (2022): 6205. http://dx.doi.org/10.3390/app12126205.
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Simultaneous construction of adjacent projects may lead to emergencies in a foundation pit group, which significantly affects the deformation and safety of foundation pits. In this study, the deformation characteristics of a deep foundation pit group and the mutual interactions among the adjacent foundation pits were observed by a monitoring system during excavation. Field data of the foundation pit group, including the lateral deflections of the enclosure pile, the ground subsidence, as well as the vertical column movements, were analyzed and compared with individual excavations in Shanghai. The field data showed that the excavation of the adjacent foundation pit reduced the lateral deformation of the enclosure structure, caused by the reduction of active earth pressure acting on the retaining pile. Furthermore, the foundation pit excavated later caused upward movements of the soil between them. However, the foundation pit excavated earlier had a negligible influence on the vertical column movements of the foundation pit excavated later. Due to the optimized excavation sequence of the deep foundation pit group, the deformation of this special excavation was well controlled.
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Paré, J. J., and J. G. Lavallée. "Excavation d'argile sensible au site de l'aménagement hydroélectrique LG-2." Canadian Geotechnical Journal 22, no. 2 (1985): 186–94. http://dx.doi.org/10.1139/t85-026.
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This paper is a review of the design adopted to establish the slopes for deep clay excavations (3 000 000 m3) made for founding rockfill embankment dams on bedrock and for clearing the tailrace tunnel portals at the LG-2 hydroelectric site. The design and excavation of soft sensitive clay deposits down to 22 m had been undertaken at a period of time when very few precedents were existing (1974). During the excavation works, only a few minor slides occurred, indicating that the design approach, using undrained shear strength analysis, was appropriate for the site conditions. Methods of excavation and hauling of material to disposal areas are also described. Key words: slope, sensitive clay, undrained strength analysis, safety factor, excavation method, behaviour.
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Cao, Chengyong, Chenghua Shi, and Mingfeng Lei. "A Simplified Approach to Design Jet-Grouted Bottom Sealing Barriers for Deep Excavations in Deep Aquifers." Applied Sciences 9, no. 11 (2019): 2307. http://dx.doi.org/10.3390/app9112307.
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This paper presents a simplified methodology for the design of jet-grouted bottom sealing barriers (temporary water-tightness structures) for deep excavations that was undertaken in deep aquifers. The bottom sealing barriers are usually required to prevent uplift failure against the water head below. Additionally, jet-grouted bottom sealing barriers are never perfect due to the uncertainties of jet grouting columns at the site, so the design must carefully consider the analysis of seepage. For these reasons, the proposed calculation procedure focuses on two different failure mechanisms (i.e., “instability failure” and “seepage failure”) of massive bottom sealing barriers. Subsequently, the design parameters of the jet-grouted bottom sealing barriers (e.g., depth and thickness) for an excavation case were determined while using the proposed design procedure. The field pumping test results show that the water-tightness performance of bottom-sealing barriers performed at site is good, which ensures that the water level inside the excavation can reach the desired level and the groundwater drawdown outside can be minimized. The leakage flow rate of bottom-sealing barriers is lower than the designed maximum allowable seepage when the water level inside stabilizes at the final period of the pumping test.
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Mazaira, A., and P. Konicek. "Intense rockburst impacts in deep underground construction and their prevention." Canadian Geotechnical Journal 52, no. 10 (2015): 1426–39. http://dx.doi.org/10.1139/cgj-2014-0359.
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In the last few decades, in both mining and civil engineering projects, deeper excavations have been carried out than in the past. With this increase in depth, rocks may overstress and rock failures can occur during excavation. When competent rock strata are encountered under high stress conditions, these failures can vary from superficial spalling to explosive rockburst. Intense rockbursts may cause fatal injuries to workers and significant loss of equipment and time. The occurrence of rockbursts is always difficult to predict and special steps and measures must be taken to control them. First, burst-prone zones must be predicted by an early exhaustive geological study and by the assessment of in situ stress level and orientation. Second, basic design parameters, e.g., shape, size, and excavation method, should be modified and adapted to the expected conditions to minimize rockburst risk. Third, in situ pre-conditioning methods, e.g., destress blasting, can be applied to decrease the capacity of the rock mass to store energy. Finally, special rock support and reinforcement systems, i.e., yielding systems, must be installed after excavation to ensure total stability of the opening. This paper reviews the geological and geomechanical factors that provoke and influence rockbursts in overstressed rock masses and the engineering measures taken to control them.
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Wei, LongYun, Nan Zhang, and Yang Li. "Research on Optimization of Deep Excavation Support Scheme Based on Distance Discriminant Analysis Method." Highlights in Science, Engineering and Technology 31 (February 10, 2023): 123–28. http://dx.doi.org/10.54097/hset.v31i.4823.
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With the rapid growth of China's national economy and urban construction, various factors make deep excavation engineering a challenging, high-risk and difficult geotechnical engineering technical subject. It plays an important role in concrete construction and has very high requirements for technology. In deep excavation engineering, in order to achieve the same supporting purpose, there are many alternative schemes, among which each scheme has its own characteristics. The choice of deep excavation support scheme is a complex multi-factor decision-making problem. Based on the idea of distance discriminant analysis theory, considering the principle of distance discriminant analysis method and the specific characteristics of deep excavation support scheme, this article tries to apply discriminant analysis method to the optimization research of deep excavation support scheme, so as to discuss the optimization design of deep excavation support project. It is hoped that the research in this article can further ensure the construction effect of building projects and provide some reference for similar projects.
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Wei, Yaping. "Research on Simulation Optimization and Construction of Deep Foundation Pit Earthwork Excavation Based on BP Nerve Network." Journal of Physics: Conference Series 2023, no. 1 (2021): 012009. http://dx.doi.org/10.1088/1742-6596/2023/1/012009.
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Abstract Deep foundation pit excavation not only faces complex hydro-geological and engineering geological conditions, but also meets many unknown engineering risks. Deep foundation pit excavation not only faces complex hydro-geological and engineering geological conditions, but also needs to make full use of BP nerve network. Based on this, this paper first analyzes the connotation and function of BP nerve network, then studies the simulation of deep foundation pit construction earthwork excavation, and finally gives the BP nerve network simulation and optimization method of deep foundation pit construction earthwork excavation.
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Zhang, Jiao. "Analytical Hierarchy Process Applied to Risk Analysis of Deep Excavation." Advanced Materials Research 250-253 (May 2011): 1646–50. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.1646.
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The application of the analytical hierarchy process (AHP) to the risk analysis of deep excavation was investigated. Firstly, the occurring probabilities of various risk factors during deep excavation were calculated. Secondly, the aftereffects of the risks were concluded by consulting the experts. Thirdly, the weight of each risk factor was obtained by AHP. Finally, the total risk of deep excavation could be evaluated by fuzzy complex evaluation. This risk analysis method was applied to evaluate the total risk of a real deep excavation, and the exemplification verified its feasibility.
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Lei, Gang, Panpan Guo, Fucai Hua, Xiaonan Gong, and Lina Luo. "Observed Performance and FEM-Based Parametric Analysis of a Top-Down Deep Excavation in Soil-Rock Composite Stratum." Geofluids 2021 (June 19, 2021): 1–17. http://dx.doi.org/10.1155/2021/6964940.
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This paper investigates the performance of a top-down deep excavation in soil-rock composite stratum. The behavior of the excavation bracing system, consisting of ground anchors and end-suspended piles, has not been well understood due to the lack of relevant research. Based on the observed data of a typical deep excavation case history for the May Fourth Square Station in Tsingtao, China, the characteristics of the horizontal and vertical pile displacements, ground surface settlements, building settlements, axial forces in ground anchors, earth pressure, and pore water pressure during excavation were analysed. Two-dimensional finite element simulations were carried out to further explore the deformation and internal force responses of end-suspended piles and to capture the effects of pile diameter, embedded depth, and rock-socketed depth on the horizontal displacement and bending moment distributions along the pile shaft. It was found that the pattern of the vertical pile displacements could be categorized into three types: rapid settlement, slow settlement, and rapid heave. The magnitudes of the ground and building responses can be well controlled within allowable limits by combining the top-down method with the adopted bracing system. Among the investigated parameters, pile diameter is dominant in affecting the horizontal pile displacement. The primary influence zone for pile bending moment varies, depending on the parameters. It is recommended that a combination of top-down method, ground anchors, and end-suspended piles be adopted for restraining excavation deformation and lowering construction costs of similar deep excavations in soil-rock composite stratum.
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Whittle, Andrew J., Youssef M. A. Hashash, and Robert V. Whitman. "Analysis of Deep Excavation in Boston." Journal of Geotechnical Engineering 119, no. 1 (1993): 69–90. http://dx.doi.org/10.1061/(asce)0733-9410(1993)119:1(69).
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Aljorany, Ala Nasir, and Ghusoon Sadiq Al-Qaisee. "Field observations and finite element 3-D analysis of soil displacements close to unsupported excavation." MATEC Web of Conferences 162 (2018): 01029. http://dx.doi.org/10.1051/matecconf/201816201029.
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Soil displacements due to unsupported deep excavation may cause severe damages to the nearby structures and foundations systems. Such excavations affect the state of stresses and displacements field of the surrounding soil. In this study, the soil displacements at five observation points were continuously monitored for23 days, which was the time period of excavation of about 7 m deep open tunnel. The reference points were installed on the ground surface at horizontal distance ranging from 1.25 to 3.25 m from tunnel excavation edge. The construction work was related to the project of developing the Army Channel/ Zeyouna section in the Eastern part of Baghdad City. The field observations indicate upward vertical displacement and outward lateral displacements during the first 10 days when the excavation depth was within 4 m. After that, the displacement trend was generally reversed. The displacement values were within 12 mm and vary from one observation point to another depending on the lateral distance of each point from excavation edge. The finite element package PLAXIS 3D was used to simulate the problem after obtaining the required soil parameters by an extensive site investigation. The analysis results in general, compare well with the field observations in terms of soil displacements at the reference points, especially during the first 10 days. This finding may reveal the reliability of the analysis results at other locations in the surrounding soil.
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Chen, Jun Sheng, Hai Hong Mo, and Shuo Zhuo Liu. "Evaluation on Effect of Building Settlement due to Adjacent Deep Excavation." Applied Mechanics and Materials 170-173 (May 2012): 637–46. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.637.
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A compound method which includes overall site stability analysis, stratum stability analysis on deep excavation boundary and 3D FEM is proposed to evaluate the effect of building settlement due to adjacent deep excavation. A typical deep excavation project was used to evaluate the feasibility of the compound method. The analysis results indicate the ground stability analysis is useful to understand the stratum situation of deep excavation and adjacent area. In 3D FEM, undulate stratum can simulate the supporting system of more accurately. The compound method brings a new analysis method for foundation pit project in complex environment and complex geological conditions.
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Shi, Xu Chao, Wu Xin Chen, and Xiu Juan Lv. "Deformation Prediction of Deep Excavation Using Support Vector Machine." Applied Mechanics and Materials 157-158 (February 2012): 66–69. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.66.
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Support Vector Machine (SVM) is a new pattern recognition method developed in recent years on the foundation of statistical learning theory. It wins popularity due to many attractive features and emphatically performance in the fields of nonlinear and high dimensional pattern recognition. Due to the complexity of the deep excavation, deformation prediction problem has not been a good solution. In the paper the support vector machine model was proposed to predict the deep excavation deformation. On the basis of deep excavation displacement data measured with real time series, the model of deep excavation displacement with time was built by SVM. Typical deformation data of deep excavation is used as learning and test samples. Comparison analysis is made between calculated values generated by SVM method and observed values. The result shows this method is feasible and effective.
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Jin, Hui Wu. "Design of Retaining and Protecting for a Deep Foundation Excavation." Advanced Materials Research 919-921 (April 2014): 1416–20. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.1416.
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Urban development often requires the construction of deep excavations. There are some difficulties during design and construction of foundation excavation, such as large engineering quantity, poor geological conditions, as well as challenges to design and construction of retaining and protecting structure. To solve these difficulties, supporting system of steel circle beam, steel pipe support and stiffened support compounding with steel pipe pile cofferdam is designed. Soil resistance calculating method is used for support structure design in all possible conditions and the result is compared with that using the classical method. With reasonable supporting process and construction measures, monitoring results including displacement of steel pipe piles and greatest axial force can meet the norm requirements. It is proved that the retaining and protecting system designed is safe and reliable. With the benefit of small deformation and high integrity, locking steel pipe piles gave full play to its locking function of water. The design method in the paper is feasible and may offer some references for similar deep foundation excavation.
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Ma, Chong, Xin Gang Wang, Bin Hu, and Hong Bing Zhan. "Numerical Simulation Analysis of Isolation Pile-Steel Shotcrete Combined Support of Deep Foundation Pit Excavation." Applied Mechanics and Materials 638-640 (September 2014): 507–11. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.507.
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The rapid development of deep foundation pit engineering, has become an important part of the urbanization construction, which brings deep excavation support of geotechnical engineering problem research also became a major issue. This paper uses the international well-known geotechnical engineering numerical simulation software FLAC3D, through 3D finite difference numerical calculation and analysis, to better simulation calculation and analysis of deep foundation pit construction site condition, forecast after excavation of the deep foundation pit deformation displacement and dangerous position, analysis of deep foundation pit excavation process isolation pile - steel shotcrete combined support effect. Three dimensional numerical model analysis and calculation in deep foundation pit engineering design and construction scheme optimization with economy is convenient wait for a obvious advantages, can for deep foundation pit excavation of deep foundation pit support design and construction to provide effective basis.
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Wong, I. H., T. Y. Poh, and H. L. Chuah. "Analysis of case histories from construction of the Central Expressway in Singapore." Canadian Geotechnical Journal 33, no. 5 (1996): 732–46. http://dx.doi.org/10.1139/t96-099-320.
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The construction of the cut-and-cover tunnels and depressed roadways of the Central Expressway (CTE) Phase II, Singapore, involved deep excavations. An extensive instrumentation program was carried out to monitor the behaviour of the excavations. The performance of three instrumented excavations from the construction of the CTE Phase II have been documented and analyzed using the finite element method (EXCAV) or finite difference method (FLAC). The results of the analyses show that the computed wall movements agree well with field measurements of wall movement and the computed wall bending moments generally agree quite well with those obtained from back-calculation. Key words: deep excavation, stiff clay, numerical analysis, displacements.
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Zhou, Zi Long, Xi Bing Li, Guo Yan Zhao, Zhi Xiang Liu, and Guang Ju Xu. "Excavation of High-Stressed Hard Rock with Roadheader." Applied Mechanics and Materials 52-54 (March 2011): 905–8. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.905.
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Drill and blast method becomes unfavorable for deep mining of hard rock. Mechanical excavation with roadheader EBZ160TY was trialed at work face with hard rock and high ground stress. Work procedure and performance of the roadheader were recorded and analyzed. The results showed that, roadheader EBZ160TY, with designed excavating strength of 80 MPa, presented amazingly good performance in hard rock with strength of 148 MPa and consumed less cost compared to drill and blast method. High stress was found to play positive role in improving its working ability. Under the gentle disturbance of roadheader excavation, the high ground stress brings the surrounding rock mass to deform into yield and lets the stress/strain energy transform into fracture energy of rock fragmentation. With the push and rotation of roadheader, structural instability of confined high-stressed particle aggregate other than rock failure by mechanical wearing happens. The results show a good application prospect for roadheader in hard rock excavation especially at deep level.
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Li, Bo, Cangqin Jia, Guihe Wang, Jun Ren, Gaofeng Lu, and Nannan Liu. "Numerical Analysis on the Performance of the Underwater Excavation." Advances in Civil Engineering 2020 (November 9, 2020): 1–14. http://dx.doi.org/10.1155/2020/8894138.
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Based on the Yongdingmen Station of Beijing Metro, the underwater excavation method for deep foundation pit was introduced. This study constructed a numerical analysis model to analyze the performance of surface settlement and lateral wall deflection in the process of underwater excavation. Results showed that this method was better to control the surface settlement and lateral wall deflection compared with other dewatering excavations. In detail, most of the surface settlement was caused during the dry excavation stage and dewatering excavation stage while the deflection caused by underwater excavation only accounted for about 10% of the total settlement. Besides, the maximum settlement occurred 0.25∼0.5 H e behind the retaining wall and the value was 0.04% H e . Similar to the result of the surface settlement, most of the lateral wall deflection had been completed before the underwater excavation, which only caused about 7% of the total deflection. The maximum wall deflection and its location were approximately 0.06% H e and 0.5 H e , respectively. Moreover, a series of 3D numerical analyses were studied on the design parameters of the underwater excavation method. This study can be used as a reference for general performance and structural design of foundation pits with underwater excavation.
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Liu, Zhen, Cui Ying Zhou, Heng Chen, and Li Guo Dong. "3D Visualization Technology for the Influence on the Surrounding Environment Caused by Excavation." Advanced Materials Research 243-249 (May 2011): 3098–104. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3098.
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On the basis of visualization of 3D stratum, deep excavation simulation is accomplished by combining with numerical analytical method, Excavation effect on surrounding environment is analyzed. By using experimental or semi-experimental models, the settlement values and their distribution features, which are caused by excavation, are discussed, by using 3D FEM, the horizontal displacement of excavated foundation ditch is calculated, and the OpenGL technology and triangle split arithmetic are chosen to implement the construction and splitting of 3D strata, the excavating process and its influence on the surrounding environment are ultimately realized. By comparing with engineering cases, the validity of analysis model and implement method are shown to be correct, feasible, and efficient.
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Liu, Yan Jun, and Li Zhen Shen. "Numerical Simulation Study on Three-Dimensional Seepage Field of Deep Excavation Dewatering in Thick Aquifer." Applied Mechanics and Materials 353-356 (August 2013): 1305–9. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.1305.
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This article describes the pumping test procedures and test results of the subway project 30m deep excavation dewatering in thick aquifer. A groundwater three-dimensional seepage numerical calculation model is established. We use the model to calculate and compare the calculated results and the actual results, obtain hydrogeological parameters by inversion. Further, we have a numerical simulation study on deep excavation dewatering with the hydrogeological parameters, the Simulation results and excavation pre-dewatering test results are consistent. Test results show that the model can reflect the deep excavation dewatering process with complex geological conditions.
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Hu, Z. F., Z. Q. Yue, J. Zhou, and L. G. Tham. "Design and construction of a deep excavation in soft soils adjacent to the Shanghai Metro tunnels." Canadian Geotechnical Journal 40, no. 5 (2003): 933–48. http://dx.doi.org/10.1139/t03-041.
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This paper presents the design and construction of a deep excavation for building foundations in saturated soil. This deep excavation was of particular interest because it was located above and beside the Shanghai Metro tunnels. The twin Shanghai Metro tunnels had to be in full operation during the deep excavation. Potential large deformation of the twin tunnels was one of the main concerns during the design and construction for the deep excavation. The paper discusses in detail the criteria and measures for controlling the soil and tunnel deformation. The measures included cast-in-place concrete diaphragm walls with bracing structural members, pumping consolidation, cementsoil mix pile systems, and rational excavation procedures. A simplified theoretical method was proposed to estimate the increment in undrained shear strength in a soft clay layer due to pumping consolidation. Furthermore, conventional finite element methods were used to predict the soil vertical and horizontal displacements induced by the excavation. Using the design and construction methods discussed in the paper, the settlement and horizontal displacement of the tunnels were successfully controlled within 5.0 mm and 9.0 mm, respectively. The curvature of longitudinal deformation curve of the tunnels was less than 1/15 000. The horizontal displacement of the braced diaphragm walls was less than 0.12% of the total excavation depth. Key words: Metro tunnels, saturated soft soil, deep excavation, design, construction, ground improvement, case studies.
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Hassan, Md Mehidi, Jong Seok Yun, Md Motiur Rahman, Yun Wook Choo, Jin-tae Han, and Dookie Kim. "Centrifugal Test Replicated Numerical Model Updating for 3D Strutted Deep Excavation with the Response-Surface Method." Applied Sciences 12, no. 20 (2022): 10665. http://dx.doi.org/10.3390/app122010665.
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Centrifugal tests provide an efficacious experimental process to predict the behavior of deep excavations, and numerical models are indispensable for demonstrating the test results and analyzing the engineering demand parameters. Uncertainty in material properties can cause simulations to differ from tests; therefore, updating the model becomes inevitable. This study presents a response-surface-based model updating technique for the nonlinear three-dimensional simulation of the centrifugal testing model of strutted deep excavation in sand. An overview of the fundamentals of the response-surface model is provided, including selecting uncertain parameters as input factors, creating a design order for training the model, building a second-order polynomial surface, and updating the input factors through targeted centrifugal results. The bending strains of diaphragm wall panels at multiple points along the depth are used to form the multiobjective function. Response-surface model predictions were well-matched with actual numerical responses, with less than a 0.5% difference. Parametric analyses could be conducted utilizing this updated strutted deep excavation model.
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Pineda-Jaimes, Jorge Arturo, Cesar Augusto García-Ubaque, and Rodrigo Elías Esquivel-Ramírez. "Assessment of Geotechnical Hazard due to Deep Excavations in Bogota Clays: A Contribution for Sustainability in Urban Environments." Revista Facultad de Ingeniería 29, no. 54 (2020): e11373. http://dx.doi.org/10.19053/01211129.v29.n54.2020.11373.
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The development of resilient and sustainable cities considers the construction of infrastructure projects that involve deep excavations. During excavations, surface displacements frequently occur that may be inadmissible for previously constructed elements of the urban environment, threatening the sustainability of already consolidated sectors. In this article, we present an approximation to the estimation of the geotechnical hazard by deep excavations in soft lacustrine soils of Bogotá, DC, using parametric numerical simulations that sought to establish the probability of occurrence of base bottom heave, and the estimation of surface displacements for variable excavation geometries. A database was consolidated from 85 projects found in geotechnical zones having soft soils in the city. From this base, statistically representative values of shear strength and stiffness were determined, and a statistically representative geotechnical profile of the lacustrine clays was prepared for parametric analyzes. The hazard estimation was developed in three stages: construction of the geotechnical model, approach of hazard scenarios and determination of the hazard level. The following parameters were considered: excavation geometry (base and height), safety factor, failure probability and vertical ground displacements (settlements). Finally, a matrix is presented to determine the hazard level by excavations in the soft soils of Bogotá, whose data provide a prior assessment that contributes to promoting resilience and sustainability of already developed areas.