Articoli di riviste: "Soil liquefaction. Silt"

1

Wang, Wu Gang, Shu Wang Yan e Xiao Qiang Liu. "Experimental Research on Liquefaction Behavior of Saturated Silt in Anhui Area". Advanced Materials Research 261-263 (maggio 2011): 943–46. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.943.

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The liquefaction for saturated silty foundation can be usually incurred under dynamic loading, such as vehicular loading and earthquakes. The silty soil liquefaction caused by earthquake is mostly the direct reason for the foundation invalidation and the structure collapse. To analyze the liquefaction behavior of saturated silty soil from Anhui Province under high seismic shock, a series of dynamic triaxial tests are carried out under the given density of remolded saturated silt with different confining pressure conditions varying from 1 m to 10 m depth in the laboratory. The increasing law of liquefaction resistance of the remolded saturated silt in Anhui province, dynamic intensity and the process of excess pore pressure are obtained from the dynamic triaxial test research. Meanwhile, the maximum liquefaction depth and the dynamic deformation properties are also illuminated based on dynamic triaxial tests, which can provide scientific data to further make engineering measures preventing the silty foundation from liquefying.

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Li, Heng, Zhao Duan, Chenxi Dong, Fasuo Zhao e Qiyao Wang. "Impact-Induced Liquefaction Mechanism of Sandy Silt at Different Saturations". Advances in Civil Engineering 2021 (29 marzo 2021): 1–14. http://dx.doi.org/10.1155/2021/6686339.

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Landslide-induced liquefaction has received extensive attention from scholars in recent years. In the study of loess landslides in the southern Loess Plateau of Jingyang, some scholars have noted the liquefaction of the near-saturated sandy silt layer that is caused by the impact of loess landslides on the erodible terrace. The impact-induced liquefaction triggered by landslides is probably the reason for the long-runout landslides on the near-horizontal terrace. In order to reveal the mechanism of impact-induced liquefaction, this paper investigates the development of pore pressure and the impact-induced liquefaction of sandy silt under the influence of saturation through laboratory experiments, moisture content tests, and vane shear tests. It has been found that both the total pressure and pore water pressure undergo a transient increase and decrease at the moment of impact on the soil, which takes 40–60 ms to complete and only about 20 ms to arrive at the peak. Moreover, silty sand with a saturation of more than 80° was liquefied under the impact, and the liquefaction occurred in the shallow layer of the soil body. The shear strength of the liquefied part of the soil is reduced to 1.7∼2.8 kPa. Soils with lower saturation did not liquefy. The mechanism of the impact-induced liquefaction can be described as follows: under impact, the water in the soil gradually fills the pores of the soil body as the pore size decreases, and when the contact between the soil particles is completely replaced by pore water, the soil body loses its shear strength and reaches a liquefied state. Soils in the liquefied state have a very high permeability coefficient, and the water inside the soil body migrates upward as the particles settle, resulting in high-moisture content in the upper soil.

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Lade, Poul V., e Jerry A. Yamamuro. "Evaluation of static liquefaction potential of silty sand slopes". Canadian Geotechnical Journal 48, n. 2 (febbraio 2011): 247–64. http://dx.doi.org/10.1139/t10-063.

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The mechanism of instability in granular soils is explained and its requirement as a forerunner to the liquefaction of level or sloping ground is described. Case histories support the observation that it is silty sands that liquefy under static and a majority of earthquake-induced conditions. Recent experiments show that clean sands do not behave similarly to silty sands. Tests on loose, silty sand indicate a “reverse” behavior with respect to confining pressure and this violates the basic assumption that loose, silty sands behave similarly to loose, clean sands. Strong correlations between fines content, compressibility, and liquefaction potential are often found for these soils. A procedure for the analysis and evaluation of static liquefaction of slopes of fine sand and silt, such as submarine slopes, mine tailings, and spoil heaps, is presented. It involves determination of the region of instability in stress space in which potential liquefaction may be initiated and determination of the state of stress in the slope. A method of finding the state of stress is developed to predict the zone of potential liquefaction in simple slopes. Trigger mechanisms for initiation of instability followed by soil liquefaction are reviewed and mechanisms of soil strengthening are discussed.

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Akhila M., Rangaswamy K. e Sankar N. "Liquefaction Susceptibility of Silty Sands and Low Plastic Clay Soils". International Journal of Geotechnical Earthquake Engineering 10, n. 2 (luglio 2019): 1–17. http://dx.doi.org/10.4018/ijgee.2019070101.

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The present study evaluates the liquefaction susceptibility of non-plastic silty sands and low plastic clay soils at different cyclic stress levels under undrained triaxial loading conditions. Six different types of soil combinations were prepared after blending the silt and clay fractions into the fine sand. Silty sands contain up to 40% non-plastic fines and low plastic clays comprise 10-20% clay fraction. The cylindrical soil specimens were constituted at the medium relative density and isotropically consolidated at 100 kPa pressure. The consolidated specimens were subjected to cyclic stress amplitudes of 0.127, 0.152 and 0.178 using sinusoidal wave loading at a frequency of 1 Hz. Results were presented in terms of pore pressure build-up and axial strain propagation with load cycles, and liquefaction resistance curves. It was found that the non-plastic silty sands and soil mixtures with plasticity indices up to 15 are more susceptible to liquefaction than the fine sands. The criterion on liquefaction susceptibility of low plastic soil mixtures shows that the soil mixtures with plasticity indices up to 15 containing 20% plastic fines exhibit a sand-like behavior and show higher liquefaction susceptibility than fine sands. It is worthy to note that the low plastic soil mixtures with PI ≥ 10 are more resistant to liquefaction than the silty sands (those contain up to 40% non-plastic fines).

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Chen, Hui Qin, Hui Ge Wu e Yong Ping Xie. "Dynamic Experimental Study on Liquefaction Behavior of Saturated Silts". Advanced Materials Research 538-541 (giugno 2012): 2453–56. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.2453.

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The liquefaction properties of silt soil which were drilled and sampled from engineering site of Tangshan area in China, were studied and analyzed by DDS-70 computer-controlled Dynamic Triaxial apparatus in this paper. And by recording the curves of dynamic stress and vibration numbers, the resisted liquefaction intensity of saturated silts were analyzed. And the enumerated experimental results of several kinds of soils can apply and guide the engineering practice in Tangshan Area.

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Fei-hong, Gu. "Evaluation of Soil Liquefaction in Harbor District in Tianjin City". Open Civil Engineering Journal 10, n. 1 (25 maggio 2016): 293–300. http://dx.doi.org/10.2174/1874149501610010293.

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The liquefaction of soils in the harbor district in Tianjin City near Tangshan, where a great earthquake occurred is a very important issue related to the soil’s compaction, grain composition and content of clay particle. This problem has not been fully considered due to the complexity and uncertainty of the soil properties data, since none of the previous investigations has been concerned about the liquefaction characteristics of this new harbor district. The evaluation of soil liquefaction has been made based on related data of the standard penetration test (SPT) from 26 investigation bore holes and 105 sieving tests. The results show that the liquefaction index of silt sand gradually decreases with the increase of the buried depth; soils less than 10.6 m in depth are of bad gradation identically. Soil less than 10.6 m in depth can be defined as liquefied soil which is further verified by sieving tests. Both the buried depth and particle grading have primarily significant influences on silt sands’ liquefaction. The results from sieve tests based on liquefied soils were found to fit well with the Tsuchida curves. It is believed that even without the in-suit SPT tests, Tsuchida boundary curves can be directly utilized to judge the liquefaction of soils in the harbor district.

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CHE, AILAN, XIANQI LUO, JINGHUA QI e DEYONG WANG. "STUDY ON CORRELATION BETWEEN SHEAR WAVE VELOCITY AND GROUND PROPERTIES FOR GROUND LIQUEFACTION INVESTIGATION OF SILTS". International Journal of Modern Physics B 22, n. 31n32 (30 dicembre 2008): 5705–10. http://dx.doi.org/10.1142/s0217979208051042.

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Shear wave velocity (V s ) of soil is one of the key parameters used in assessment of liquefaction potential of saturated soils in the base with leveled ground surface; determination of shear module of soils used in seismic response analyses. Such parameter can be experimentally obtained from laboratory soil tests and field measurements. Statistical relation of shear wave velocity with soil properties based on the surface wave survey investigation, and resonant column triaxial tests, which are taken from more than 14 sites within the depth of 10 m under ground surface, is obtained in Tianjin (China) area. The relationship between shear wave velocity and the standard penetration test N value (SPT-N value) of silt and clay in the quaternary formation are summarized. It is an important problem to research the effect of shear wave velocity on liquefaction resistance of saturated silts (sandy loams) for evaluating liquefaction resistance. According the results of cyclic triaxial tests, a correlation between liquefaction resistance and shear wave velocity is presented. The results are useful for ground liquefaction investigation and the evaluation of liquefaction resistance.

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Polito, Carmine P., e Erin L. D. Sibley. "Threshold fines content and behavior of sands with nonplastic silts". Canadian Geotechnical Journal 57, n. 3 (marzo 2020): 462–65. http://dx.doi.org/10.1139/cgj-2018-0698.

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The threshold fines content of a sand with nonplastic fines represents the silt content where the soil transitions from being a sand matrix, with silt particles entirely contained in the voids between the sands, to being a silt matrix that contains isolated sand grains. A laboratory testing program was performed on a series of mixtures of sand and silt, with silt contents ranging from 0% to 45%, to determine if the friction angle, cyclic resistance, and normalized dissipated energy per unit volume required to initiate liquefaction changed based upon the silt content of the soil relative to the threshold fines content. These data were evaluated with respect to whether the silt content of the specimens was below the lower-bound threshold fines content or above the upper-bound threshold fines content. It was determined that soils above the upper-bound threshold fines content had lower friction angles, lower cyclic resistances, and required less normalized dissipated energy per unit volume to initiate liquefaction than soils below the lower-bound threshold fines content. It was also shown that under the larger strains experienced during monotonic testing, the friction angle did not reach a constant value until it was well above the upper-bound limiting silt content.

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Polito, Carmine P., e James R. Martin. "A Reconciliation of the Effects of Non-Plastic Fines on the Liquefaction Resistance of Sands Reported in the Literature". Earthquake Spectra 19, n. 3 (agosto 2003): 635–51. http://dx.doi.org/10.1193/1.1597878.

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The literature presents several seemingly contradictory reports concerning the effects of non-plastic (i.e., silty) fines content on the liquefaction resistance of sands. These seemingly contradictory trends were reconciled in light of the results of a recent study by the authors that linked cyclic resistance and relative density. It was shown that the trend of decreasing cyclic resistance with increasing silt content reported in the literature could be explained by considering the soil's relative density. The same argument was made for the trend of decreasing and then increasing cyclic resistance with increasing silt content. The concept that cyclic resistance is controlled by the sand skeleton void ratio of the soil was also reconciled with the results of the authors’ previous study. The trend of increasing cyclic resistance (without a corresponding initial decrease) with increasing silt content that has been reported in the literature does not appear to occur in non-plastic silts.

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Du, Guangyin, Changhui Gao, Songyu Liu, Qian Guo e Tao Luo. "Evaluation Method for the Liquefaction Potential Using the Standard Penetration Test Value Based on the CPTU Soil Behavior Type Index". Advances in Civil Engineering 2019 (12 marzo 2019): 1–8. http://dx.doi.org/10.1155/2019/5612857.

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Taking the project of the Su-xin highway treated by using the resonant compaction method as the reference, a new method for the evaluation of liquefaction potential is proposed based on the piezocone penetration test (CPTU) and the standard penetration test (SPT). The soil behavior type index (Ic) obtained from CPTUs and the standard penetration test index (N63.5), obtained from SPTs, are analyzed for saturated silty sand and silt. The analysis result reveals a linear relationship between N63.5 and Ic, given by N63.5=−18.8Ic+52.0. The larger the value of Ic is, the greater the viscosity of soil is, and the smaller the value of N63.5 is. According to the method, liquefaction assessment of saturated silty sand and silt foundation can be conducted by using N63.5 based on the Code of Seismic Design of Building. N63.5 is expressed by a single Ic, which is calculated from the CPTU data. Compared with existing evaluation methods, this method can provide continuous standard penetration test values, moreover, this method involves a simple calculation, and the results obtained using the method are reliable.

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Shuttle, Dawn A., e John Cunning. "Liquefaction potential of silts from CPTu". Canadian Geotechnical Journal 44, n. 1 (1 gennaio 2007): 1–19. http://dx.doi.org/10.1139/t06-086.

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Silt tailings (slimes) are difficult materials to test in that, like sands, it is extremely difficult to obtain undisturbed samples and subsequently re-establish them in a triaxial cell for element testing in a laboratory in anything approaching their in situ condition. Evaluation of silt tailing behaviour has to depend on in situ tests, and the piezocone (CPTu) in particular. However, CPTs in silt generate substantial excess pore pressure and there is no established methodology to evaluate the measured responses in terms of soil properties, as drained sand-based CPT interpretation is inapplicable. A case history of particularly loose silt tailings is reported in which the National Center for Earthquake Engineering Research (NCEER) liquefaction assessment method would lead to uncertainty in the liquefaction potential. However, the extremely high CPTu excess pore pressure ratio, Bq, and low dimensionless CPT resistance, Qp, at this site indicates liquefaction is likely occurring during pushing of the CPT. Detailed finite element simulations of the CPT using a critical state model provided an effective stress framework to evaluate the in situ state parameter of the silt from the measured CPT data. This framework shows that the group of dimensionless CPT variables Q(1 – Bq) + 1 is fundamental for the evaluation of undrained response during CPT sounding. And, despite the high silt content, the interpretation indicates that the tailings are indeed liquefiable.Key words: liquefaction, CPT, silt, finite element, critical state.

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Boulanger, Ross W., Mark W. Meyers, Lelio H. Mejia e Izzat M. Idriss. "Behavior of a fine-grained soil during the Loma Prieta earthquake". Canadian Geotechnical Journal 35, n. 1 (1 febbraio 1998): 146–58. http://dx.doi.org/10.1139/t97-078.

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Results of an investigation into the behavior of a fine-grained clayey soil at Moss Landing during the 1989 Loma Prieta earthquake are presented. A deposit of this soil underlies portions of the Moss Landing Marine Laboratory that experienced up to 1.3 m of lateral spreading deformations during this magnitude 7 earthquake. Silty clay from the deposit erupted to the surface in a "soil boil" characteristic of liquefaction, during and immediately after the earthquake. A sample from the silty clay boil had a liquid limit of 38, a plasticity index of 17, and a <5 µm fraction of 24%, and thus would be considered nonliquefiable according to commonly used criteria. Analysis of cyclic triaxial test data suggests that portions of the silty clay deposit likely developed high residual excess pore pressures (ru,r approx 80-90%) and significant shear strains during the earthquake and thus likely contributed to the observed lateral deformations. The field and laboratory data show that commonly used criteria for identifying "liquefiable" clayey soils should be applied with caution and should not be indiscriminately viewed as a substitute for detailed laboratory and in situ testing of low plasticity fine-grained soils.Key words: liquefaction, cyclic loading, silt, clay, earthquake, case history.

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Jia, Min Cai, e Bing Ye Wang. "Liquefaction Testing of Stratified Sands Interlayered with Silt". Applied Mechanics and Materials 256-259 (dicembre 2012): 116–19. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.116.

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The cyclic behavior of stratified sands interlayered with silt is at present poorly understood, although stratified sands exist for various soil deposits and hydraulic fill, which have a history of liquefaction during earthquakes. The main objective of this research project was to compare the cyclic behavior of stratified and homogeneous sands for various silt contents. A comprehensive experimental program was undertaken in which stain-controlled undrained cyclic triaxial tests for stratified sand samples interlayered with different thickness silt were performed. The silt thickness ranged from 0 to 80mm was considered. The confining pressure in all test series was 100kPa. The results indicate that the thickness of the silt seam sandwiched in the sand samples has a significant influence on the liquefaction resistances of layered sands. In other words, there is a critical thickness of silt seam that the saturated stratified sands have a critical shear strain. This finding justifies applying the laboratory tests results of homogeneously reconstituted samples to the field conditions for the range of variable studied.

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Verma, Priyesh, Ainur Seidalinova e Dharma Wijewickreme. "Equivalent number of uniform cycles versus earthquake magnitude relationships for fine-grained soils". Canadian Geotechnical Journal 56, n. 11 (novembre 2019): 1596–608. http://dx.doi.org/10.1139/cgj-2018-0331.

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In current geotechnical seismic design practice, the empirical correlation between equivalent number of uniform cycles (Neq) of shaking and earthquake magnitude (Mw) forms an integral part of liquefaction potential evaluation. This relationship, in turn, is used to derive the magnitude scaling factors that are commonly used in field-based liquefaction evaluation procedures. The Neq versus Mw relationship for liquefaction assessment was examined for fine-grained soils using time-histories in the range 5 < Mw ≤ 9, especially including strong ground motion time-histories from the latest subduction zone earthquakes with Mw > 8.0. The experimental database available from cyclic direct simple shear tests conducted on natural fine-grained soils retrieved from undisturbed soil sampling was used to obtain the cyclic shear resistance weighting curves for the study. The work presented herein has contributed to further improving the current models used to represent magnitude scaling factor (MSF) values for large earthquake magnitudes and the functional dependency of this parameter on soil type. The MSF–Mw curve derived for low-plastic Fraser River Delta silt lies in-between the MSF curves derived for clean sand and clay, resonating with the inferences that have been made that the silt behavior can neither be considered sand-like nor clay-like.

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QI, JINGHUA, AILAN CHE e XIURUN GE. "A STUDY ON THE STABILITY OF EARTH DAM SUBJECTED TO THE SEISMIC LOAD". International Journal of Modern Physics B 22, n. 31n32 (30 dicembre 2008): 5711–16. http://dx.doi.org/10.1142/s0217979208051054.

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For ensuring the earth dam's stability of Wangqingtuo reservoir when silt liquefaction happens during Tangshan earthquake, a large amount of laboratory soil tests and field measurements have been performed to obtain the mechanic properties of the soil and silt dynamic parameters. On the basis of the soil tests, the equivalent linear constitutive model is employed in the dynamic numerical simulation of the typical dam and the results indicate that the shear deformation is induced by the foundation liquefaction with the help of the geo-slope software. Moreover, the stability analysis is performed using the finite element elasto-plastic model that is considered the Mohr-Coulomb failure criteria to calculate the stability factor. The factors indicate the local instability would take place because of the shear action. At last, the measures are introduced to the designers for preventing the dam from the instability.

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El Takch, Ali, Abouzar Sadrekarimi e Hesham El Naggar. "Cyclic resistance and liquefaction behavior of silt and sandy silt soils". Soil Dynamics and Earthquake Engineering 83 (aprile 2016): 98–109. http://dx.doi.org/10.1016/j.soildyn.2016.01.004.

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Liu, Qi Xia, e Yang Bai. "The Application of Compaction Sand Pile in the Yellow River-Crossing Project for South-to-North Water Diversion". Applied Mechanics and Materials 226-228 (novembre 2012): 1396–400. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1396.

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In the construction of Yellow River-Crossing Project for the Middle Route of the South-to-North Water Transfer, the silt, silty sand and fine sand widely exist in the foundation, that it need to be processed in the region where the possibility of sand liquefaction because of the low bearing capacity. We had a detailed study and experiment for the sand compaction pile of the axis and the outside of the channel, and determined the compactness of pile body, pile length and the construction technology through the test. We also debugged the concrete construction parameters such as the amount of filling sand and stone, hoisting height and speed, extrusion times and so on. For these experiments, we attained the purpose of increasing the relative density, preventing sandy soil liquefaction, improving the shear strength of the foundation soil and the bearing capacity of the foundation, so as to reduce the foundation settlement.

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Díaz-Rodríguez, J. A., V. M. Antonio-Izarraras, P. Bandini e J. A. López-Molina. "Cyclic strength of a natural liquefiable sand stabilized with colloidal silica grout". Canadian Geotechnical Journal 45, n. 10 (ottobre 2008): 1345–55. http://dx.doi.org/10.1139/t08-072.

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This paper summarizes the experimental results of a series of cyclic simple shear tests on liquefiable silty sand with and without sample improvement with colloidal silica grout. The objective of the paper is to evaluate the effectiveness of colloidal silica grouting in reducing the liquefaction potential of natural silty sand. Colloidal silica was selected as a stabilizing material due to its low viscosity, wide range of gel times, nontoxicity, and low cost. The soil tested in this experimental program is a poorly graded sand with 11.5% of nonplastic silt from the Port of Lázaro Cárdenas, México. Colloidal silica treated and untreated sand specimens show different pore pressure response and deformation behavior under cyclic loading in simple shear tests. The results indicate that, for a given initial relative density and initial effective vertical stress, liquefiable silty sand specimens stabilized with colloidal silica grout generally exhibit significant gain in liquefaction resistance compared with untreated specimens. It was also found that the colloidal silica grout reduces considerably the rates of pore pressure generation and shear strain of the silty sand specimens subjected to cyclic loading.

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Karim, Hussein H., Zeena W. Samueel e Dalia A. Abdul Hussein. "Correlation of Soil Liquefaction Potential Index and Geotechnical Properties for Baghdad City, Iraq". Engineering and Technology Journal 38, n. 6A (25 giugno 2020): 813–24. http://dx.doi.org/10.30684/etj.v38i6a.189.

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This paper comprises the study and analysis of Baghdad soil for eight geotechnical properties, which extract from field experiments of 630 boreholes with depth taken to 30m and representing 200 sites. Soil investigation reports are composed from altered laboratory tests. The soil layers. Divided into each 2m, which means 15 studied’ layers and soil properties values were embraced and submitted. in tables and charts which have been analysis-using excel2013 and check the charts using curve expert program to get the relationships between the properties values and the factor of safety against liquefaction. The correlations between liquefaction potential represented by the safety factor and soil properties for the available data of 200 sites in Baghdad have been studied and statistically studied ‘to evaluate both of soil properties and liquefaction potential index. Eight factors affecting liquefaction have been correlated with factor of safety for all earthquake magnitudes (ML= 4to 6.5 with 0.5 interval). These factors are, groundwater table, fill layer depth, standard penetration test (SPT- N value), saturated unit’ weight (γ), Relative density (Dr %), soil fractions (clay, silt and sand %), and total settlement (Stot). For better correlations, the same factors have been correlated with safety factor but for each earthquake magnitude alone.

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SATO, Kenichi, Tetsumi HORI, Takuro FUJIKAWA e Chikashi KOGA. "EFFECT OF SILT CONTENTS ON LIQUEFACTION PROPETIES OF SHORT FIBERS MIXED SOIL". Geosynthetics Engineering Journal 31 (2016): 235. http://dx.doi.org/10.5030/jcigsjournal.31.235.

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He, Liangcai, Jose Ramirez, Jinchi Lu, Liang Tang, Ahmed Elgamal e Kohji Tokimatsu. "Lateral spreading near deep foundations and influence of soil permeability". Canadian Geotechnical Journal 54, n. 6 (giugno 2017): 846–61. http://dx.doi.org/10.1139/cgj-2016-0162.

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A three-dimensional finite element (FE) model is calibrated based on a large-scale (1g) shake-table experiment. In this experiment, single piles were subjected to liquefaction-induced lateral spreading. The testing configuration, experimental results, and FE framework are presented and discussed. The presence of piles in this fully saturated ground model caused a significant reduction in the extent of accumulated lateral soil deformation. In this regard, high shear strains, additional to those in the free field, occur as the soil moves around the piles in the downslope direction. The associated shear-induced tendency for dilation increases the effective confinement, and reduces the resulting downslope deformations. As such, an FE parametric study is undertaken to investigate the effect of soil permeability on this observed liquefaction-induced lateral response. As the prescribed soil permeability increased (in the silt–sand range), higher levels of ground lateral deformation occured, albeit with a lower pile head displacement and lateral load. Eventually, high permeability (in the gravels range) precluded the accumulation of significant excess pore pressure, with low levels of both soil and pile lateral displacement. On this basis, permeability is highlighted as a critical potentially primary parameter in dictating the effects of liquefaction-induced lateral load on embedded foundation systems.

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Akhila, M., K. Rangaswamy e N. Sankar. "Undrained Response and Liquefaction Resistance of Sand–Silt Mixtures". Geotechnical and Geological Engineering 37, n. 4 (18 dicembre 2018): 2729–45. http://dx.doi.org/10.1007/s10706-018-00790-0.

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Mahmoudi, Youcef, Abdellah Cherif Taiba, Leila Hazout, Wiebke Baille e Mostefa Belkhatir. "Influence of Soil Fabrics and Stress State on the Undrained Instability of Overconsolidated Binary Granular Assemblies". Studia Geotechnica et Mechanica 40, n. 2 (3 ottobre 2018): 96–116. http://dx.doi.org/10.2478/sgem-2018-0011.

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AbstractThe instability of saturated granular soils in field conditions generates drastic collapse in terms of runoff deformation because of its failing to sustain naturally applied loading conditions such as earthquakes, wave actions and vibrations. The objective of this laboratory investigation is to study the effects of the depositional methods, overconsolidation ratio (OCR) and confining pressure on the undrained instability shear strength of medium dense (Dr = 52%) sand–silt mixtures under static loading conditions. For this purpose, a series of undrained monotonic triaxial tests were carried out on reconstituted saturated silty sand samples with fines content ranging from 0% to 40%. Three confining pressures were used (P’c = 100, 200 and 300 kPa) in this research. The sand–silt mixture samples were prepared using two depositional methods, dry funnel pluviation (DFP) and wet deposition (WD), and subjected to two OCRs (1 and 2). The obtained instability lines and friction angles indicate that the funnel pluviated samples exhibit strain hardening compared to the wet deposited samples and that normally consolidated and overconsolidated wet deposited clean sandy samples were very sensitive to static liquefaction. The test results also indicate that the instability friction angle increases with the increase in the OCR expressing soil dilative character tendency increase. The instability friction angle decreases with the increase in the fines content for DFP and the inverse tendency was observed in the case of WD.

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Karim, Mohammad Emdadul, e Md Jahangir Alam. "Effect of non-plastic silt content on the liquefaction behavior of sand–silt mixture". Soil Dynamics and Earthquake Engineering 65 (ottobre 2014): 142–50. http://dx.doi.org/10.1016/j.soildyn.2014.06.010.

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Bao, Xiaohua, Guanlin Ye, Bin Ye, Yanbin Fu e Dong Su. "Co-seismic and post-seismic behavior of an existed shallow foundation and super structure system on a natural sand/silt layered ground". Engineering Computations 33, n. 1 (7 marzo 2016): 288–304. http://dx.doi.org/10.1108/ec-05-2015-0134.

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Abstract (sommario):

Purpose – The purpose of this paper is to evaluate the co-seismic and post-seismic behaviors of an existed soil-foundation system in an actual alternately layered sand/silt ground including pore water pressure, acceleration response, and displacement et al. during and after earthquake. Design/methodology/approach – The evaluation is performed by finite element method and the simulation is performed using an effective stress-based 2D/3D soil-water coupling program DBLEAVES. The calculation is carried out through static-dynamic-static three steps. The soil behavior is described by a new rotational kinematic hardening elasto-plastic cyclic mobility constitutive model, while the footing and foundation are modeled as elastic rigid elements. Findings – The shallow (short-pile type) foundation has a better capacity of resisting ground liquefaction but large differential settlement occurred. Moreover, most part of the differential settlement occurred during earthquake motion. Attention should be paid not only to the liquefaction behavior of the ground during the earthquake motion, but also the long-term settlement after earthquake should be given serious consideration. Originality/value – The co-seismic and post-seismic behavior of a complex ground which contains sand and silt layers, especially long-term settlement over a period of several weeks or even years after the earthquake, has been clarified sufficiently. In some critical condition, even if the seismic resistance is satisfied with the design code for building, detailed calculation may reveal the risk of under estimation of differential settlement that may give rise to serious problems.

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26

Yalcin, A., C. Gokceoglu e H. Sönmez. "Liquefaction severity map for Aksaray city center (Central Anatolia, Turkey)". Natural Hazards and Earth System Sciences 8, n. 4 (7 luglio 2008): 641–49. http://dx.doi.org/10.5194/nhess-8-641-2008.

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Abstract. Turkey having a long history of large earthquakes have been subjected to progressive adjacent earthquakes. Starting in 1939, the North Anatolian Fault Zone (NAFZ) produced a sequence of major earthquakes, of which the Mw 7.4 earthquake that struck western Turkey on 17 August 1999. Following the Erzincan earthquake in 1992, the soil liquefaction has been crucial important in the agenda of Turkey. Soil liquefaction was also observed widely during the Marmara and the Düzce Earthquake in 1999 (Sönmez, 2003). Aksaray city center locates in the central part of Turkey and the Tuzgolu Fault Zone passes through near the city center. The fault zone has been generated to moderate magnitude earthquakes. The geology of the Aksaray province basin contains Quaternary alluvial deposits formed by gravel, sand, silt, and clay layers in different thickness. The Tuzgolu Fault Zone (TFZ) came into being after the sedimetation of alluvial deposits. Thus, the fault is younger from lithological units and it is active. In addition, the ground water level is very shallow, within approximately 3 m from the surface. In this study, the liquefaction potential of the Aksaray province is investigated by recent procedure suggested by Sonmez and Gokceoglu (2005). For this purpose, the liquefaction susceptibility map of the Aksaray city center for liquefaction is presented. In the analysis, the input parameters such as the depth of the upper and lower boundaries of soil layer, SPT-N values, fine content, clay content and the liquid limit were used for all layers within 20 m from the surface. As a result, the category of very high susceptibility liquefaction class was not observed for the earthquake scenario of Ms=5.2, 4.9% of the study area has high liquefaction susceptibility. The percentage of the moderately, low, and very low liquefied areas are 28.2%, 30.2%, and 36.3%, respectively. The rank of non-liquefied susceptibility area is less than 1%.

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27

Tini, Tini, Adrin Tohari e Mimin Iryanti. "Analisis Potensi Likuifaksi Akibat Gempa Bumi Menggunakan Metode SPT (Standar Penetration Test) Dan Cpt (Cone Penetration Test) Di Kabupaten Bantul, Yogyakarta". Wahana Fisika 2, n. 1 (20 giugno 2017): 8. http://dx.doi.org/10.17509/wafi.v2i1.7022.

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Abstract (sommario):

Gempa bumi yang terjadi di daerah Bantul, Yogyakarta pada 27 Mei 2006 dengan magnitudo gempa bumi sebesar 6.3 SR dapat menyebabkan terjadinya bahaya likuifaksi yang dapat merusak bangunan khususnya di wilayah Bantul Yogyakarta. Investigasi geoteknik yang telah dilakukan di Bantul, Yogyakarta dapat memberikan gambaran lapisan tanah yang berpotensi terjadinya likuifaksi. Analisis potensi likuifaksi dilakukan berdasarkan data SPT (Standard Penetration Test) dan CPT (Cone Penetration Test) dengan percepatan maksimum tanah menurut Gutenberg Richter di daerah penelitian rata-rata bernilai sebesar 2.93 m/s2 dan menurut Donovan sebesar 2.88 m/s2. Hasil analisis penelitian menunjukan bahwa lapisan tanah yang berpotensi likuifaksi didominasi oleh jenis tanah pasir lanauan da lanau pasiran yang berada pada kedalaman 0.2 – 3 m, 0.4 m, 2.4 m, 3.6 m, 7.6 – 7.8 m dan 8.2 m. Pengaruh percepatan maksimum tanah menurut Gutenberg Richter lebih besar terhadap terjadinya likuifaksi daripada menurut Donovan. Perbandingan hasil analisis potensi likuifaksi antara data SPT (Standard Penetration Test ) dan CPT (Cone Penetration Test) pada daerah penelitian menunjukan adanya kesamaan potensi likuifaksi pada lapisan tanah dengan kedalaman yang sama diantaranya pada kedalaman 0.2 m-4 m, dengan nilai Cyclic Strees Ratio (CSR) rata-rata sebesar 0.2, sedangkan berdasarkan nilai Cyclic Resistance Ratio (CRR) terdapat perbedaan nlai. Analisis berdasarkan data CPT lebih baik daripada data SPT karena data CPT lebih rapat daripada data SPT.The earthquake that occurred in Bantul, Yogyakarta on May 27, 2006 with the magnitudo of the earthquake of 6.3 SR can caused liquefaction hazard which could damage to teh building in the municipals of Bantul, Yogyakarta. Geotechnical investigation was carried in Bantul Yogyakarta, can give information about liquefaction hazard in soil layer. The liquefaction potential lanalysis was conducted using SPT and CPT methods, with Gutenberg-Richter’s maximum ground acceleration is 2.93 m/s2 and Donovan’s maximum ground acceleration is 2.88 m/s2. Result of liquefaction analysis indicate that the soil layer domination of silty sand dan sandy silt at the depth of 0.2 – 3 m, 3.6 m, 4 m 7.6 – 7.8 m and 8.2 m. Gutenberg-Richter’s maximum ground acceleration having influential for liquefaction potential better than Donovan’s maximum ground acceleration. Ratio result of liquefaction was conducted using SPT same as soil layer with CPT in resech location at the depth 0.2 m-4 m, with value Cyclic Strees Ratio (CSR) is 0.2. Even value Cyclic Resistances Ratio (CSR) have different value. The liquefaction potential lanalysis was conducted using CPT method better than SPT methods.

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Sui, Titi, Chi Zhang, Jinhai Zheng e Dong-Sheng Jeng. "DYNAMIC RESIDUAL SEABED RESPONSE AROUND A MOVABLE PILE FOUNDATION". Coastal Engineering Proceedings, n. 36 (30 dicembre 2018): 20. http://dx.doi.org/10.9753/icce.v36.sediment.20.

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Abstract (sommario):

Wave-induced seabed soil response and its resultant liquefaction is common observed in a silt seabed with relative poor drainage condition, which poses a great threaten to the foundation safety of marine structures. Regarding the governing equations, three different approaches namely the Fully-dynamic (FD), Partialdynamic (PD) and Quasi-static (QS) model, have been used in the previous studies. Among these, both PD and FD approaches consider the effect of the inertial terms of soil skeleton/fluid. It has been reported in the literature that effects of the inertial terms on the seabed response could not be neglected, especially for the seabed around a movable structure (Ulker et al., 2010). However, these studies only focused on the oscillatory mechanism which are probably seen in a sandy seabed with high permeability. Recently, Zhao et al. (2017) investigated the residual soil response around a pile foundation by integrating a RANS wave model and a QS seabed model. In their study, the inertial terms of soil skeleton and pore water were neglected. To the authorsâ€™ best knowledge, up to now, effects of the inertial terms on the residual response of a silt seabed have not been investigated.

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29

Sitharam, T. G., B. V. Ravishankar e S. M. Patil. "Liquefaction and Pore Water Pressure Generation in Sand". International Journal of Geotechnical Earthquake Engineering 3, n. 1 (gennaio 2012): 57–85. http://dx.doi.org/10.4018/ijgee.2012010104.

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Cyclic strain controlled laboratory triaxial undrained tests were performed on sand samples collected from earthquake affected Ahmedabad City of Gujarat (India). To study the factors controlling the liquefaction potential and pore pressure generation, cyclic strain controlled triaxial tests were carried out on (a) base sand, (b) pure sand, and (c) pure sand and non plastic silt mixture. All the tests were conducted on reconstituted soil samples and consolidated isotropically to different effective confining pressures. Base sand, clean sand and sand with non-plastic fines were tested using cyclic strain controlled triaxial undrained tests for different combination of shear strain amplitudes, initial effective confining pressure, and relative density (RD). In case of base sand and pure sand both have qualitatively the same liquefaction and pore pressure generation behaviors. For sand with non plastic fines, basic concept of limiting fines content (LFC) is justified and shown that how the behavior of mixture undergoes transition before and after LFC. This transitional behavior is observed both in the liquefaction strength and pore pressure generation. To obtain a mean relationship between liquefaction strength, pore pressure generation on relative density, confining pressure and shear strain amplitude, approaches previously adopted by Talaganov (1996) are used.

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30

Zamani, Atefeh, Brina M. Montoya e Mohammed A. Gabr. "Investigating challenges of in situ delivery of microbial-induced calcium carbonate precipitation (MICP) in fine-grain sands and silty sand". Canadian Geotechnical Journal 56, n. 12 (dicembre 2019): 1889–900. http://dx.doi.org/10.1139/cgj-2018-0551.

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Abstract (sommario):

Microbial-induced calcium carbonate precipitation (MICP) is a sustainable soil improvement method with the potential for improving the engineering properties of sand and silty soils and therefore their resistance to liquefaction-inducing events. Work presented herein experimentally investigates the changes in hydraulic conductivity of fine sands and silty sands as a result of MICP treatment. In addition, numerical modeling is conducted to assess the changes in allowable injection rate and radius of influence for the delivery of the MICP process at the field scale. The hydraulic conductivity of Nevada sand and silty sand with 15% fines content decreased through MICP application with the trend of reduction being similar for both soils. Numerical modeling results show that with the progress of the MICP process, injection rates can be increased for Nevada sand, but remain unchanged for Nevada sand with 15% silt content (after MICP treatment up to a shear wave velocity about 400 m/s.) The presence of fines by itself leads to generation of higher levels of pore-water pressure during the injection process, which necessitates higher strength improvement to prevent development of excessive plastic strains. Therefore, improvement in shear strength and stiffness relative to the magnitude of the hydraulic conductivity level and its rate of change during the MICP process is a key parameter in determining the radius of treatment.

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31

Quan, Xiao Juan, Xin Ming Guo e Kai Shi. "Analysis on the Impact of the Constitutive Model of Trains Vibration in Shield Tunnel". Applied Mechanics and Materials 501-504 (gennaio 2014): 1787–91. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.1787.

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In this paper, with the in-situ engineering project Shiziyang tunnel of Guangzhou-Shenzhen Railway, under the disturbance of high-speed train vibration load, the shield tunnels dynamic response and foundations sand liquefying phenomenon are studied ,where they are mainly located in saturated and soft soil. Due to the tunnel going through the paralic deposited silt layer, silty soil, alluvial clay layer and the layer of fine sand or coarse sand layer, under the condition that enduring a long time of high-speed train running, which may easily lead to the foundation liquefaction and asymmetric settlement. At the entrance of the tunnel, with the poor geological conditions and weak cladding, which can easily induce sliding and collapse, where the geological conditions of this part is the most unfavorable place. Through numerical simulations, the main factor the constitutive model is explored, which may affect the single high-speed train loads on the vibration response of the train in shield tunnel and the law of accumulation and dissipation for pore water pressure.

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32

Karakan, Eyyub, Nazar Tanrinian e Alper Sezer. "Cyclic undrained behavior and post liquefaction settlement of a nonplastic silt". Soil Dynamics and Earthquake Engineering 120 (maggio 2019): 214–27. http://dx.doi.org/10.1016/j.soildyn.2019.01.040.

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33

Amini, F., e K. M. Sama. "Behavior of stratified sand–silt–gravel composites under seismic liquefaction conditions". Soil Dynamics and Earthquake Engineering 18, n. 6 (agosto 1999): 445–55. http://dx.doi.org/10.1016/s0267-7261(99)00011-1.

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34

Pokhrel, Rama Mohan, Jiro Kuwano e Shinya Tachibana. "Liquefaction hazard zonation mapping of the Saitama City, Japan". Journal of Nepal Geological Society 40 (1 dicembre 2010): 69–76. http://dx.doi.org/10.3126/jngs.v40i0.23598.

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Abstract (sommario):

Liquefaction hazard zonation mapping of the Saitama City targeted on the Kanto Plain NW Edge Fault is described in this paper. The study involves the geotechnical properties of the alluvial soil of the city including Standard Penetration Test (SPT), shear wave velocity and other geological data analysis. The city being highly urbanized is situated on the soft soil (alluvial deposits) at the proximity of an active seismic fault that has increased the possibility of liquefaction hazard in the area. Kanto Plain NW Edge Fault is an active fault that lies very near to the Saitama City having the estimated possible earthquake magnitude of 7.4. The possible peak horizontal ground acceleration (amax) from this earthquake is calculated as from 0.15 g to 0.30 g. By considering all possible acceleration values the liquefaction potential maps were prepared and presented in this paper. Additionally, the shear wave velocity is very low and amplification ratio is very high at the marshy deposit but it has comparatively high velocity and low amplification ratio at the marine loam deposit area of the Omiya Plateau. In this paper the liquefaction potential of the area is expressed in terms of liquefaction potential index (PL). The PL value for the clayey silt deposit in the marshy area with shallow water table is very high. In addition, the PL value in the marine loam deposit of the Omiya Plateau is less which indicates that loam deposit has less liquefaction potential than marshy deposit. The map obtained from this study was validated with the field condition of the study area. Hence, it is expected that this study will assist in characterizing the seismic hazards and its mitigation and will provide valuable information for urban planning in the study area in future.

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35

Rowe, R. Kerry, e Ahmed Mabrouk. "Three-dimensional analysis of unanticipated behavior of a deep excavation". Canadian Geotechnical Journal 55, n. 11 (novembre 2018): 1647–56. http://dx.doi.org/10.1139/cgj-2017-0511.

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Abstract (sommario):

A three-dimensional (3D) effective stress finite element analysis, modified to account for hydrofracturing and gassy soil behavior, is used to examine the potential for the venting of water and gas from a bedrock aquifer and through 13–14 m of low permeability clayey silt between the base of the excavation and the bedrock following excavation to about 24 m in an approximately 40 m thick clayey silt deposit. The clayey deposit contained sand lenses with dissolved gas. The analysis predicts that the exsolution of this dissolved gas, caused by a reduction in total stress due to the excavation, results in liquefaction of the sand in the lenses and consequent lateral deformations of the side slopes. The analysis predicts hydrofracturing through the remaining clayey silt when the excavation reaches its final depth and this explains the venting of water and gas from the underlying aquifer that was observed above a local bedrock high. The presence of gassy sand lenses created weak zones within the clayey deposit that influenced the path of the hydrofracturing. However, the analyses suggest that, for the depth of excavation and bedrock elevation examined, hydrofracturing and subsequent venting would have occurred even if there had been no sand lenses.

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36

Rodríguez, R. "Hydrogeotechnical characterization of a metallurgical waste". Canadian Geotechnical Journal 43, n. 10 (1 ottobre 2006): 1042–60. http://dx.doi.org/10.1139/t06-061.

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This paper presents the results of hydrogeotechnical characterization tests carried out on the metallurgical waste (MW) from a tailings impoundment located on the terraces of the Moa River, Cuba. Characterization of the MW includes chemical and mineralogical analysis, oedometer tests, triaxial tests, tensile strength tests, determination of the water retention curve, and shrinkage and permeability tests. The MW, which has a grain-size distribution similar to that of a silt, mainly contains iron and heavy metals minerals and has low plasticity. Consolidated undrained triaxial tests on remoulded samples indicate a dilative behaviour, with a decrease in pore-water pressure near failure. The material is susceptible to liquefaction when subjected to a cyclic load in the triaxial test. Hydraulic conductivity, soil stiffness, and compressive and tensile strength of the MW have an important dependence on the degree of saturation and vary significantly during the drying process. The results indicate that, during the drying process, cracks in the MW initiate in quasi-saturated conditions. The cracks increase the hydraulic conductivity by more than one order of magnitude compared with that of intact samples of MW. The main environmental risk with this MW is the possibility of liquefaction under a cyclic load due to an earthquake and the increase in saturated hydraulic conductivity due to desiccation cracks.Key words: desiccation cracks, hydrogeotechnical properties, liquefaction, metallurgical waste, characterization.

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Emdadul Karim, Mohammad, e Md Jahangir Alam. "Erratum to “Effect of non-plastic silt content on the liquefaction behavior of sand–silt mixture” [Soil Dyn. Earthq. Eng. (2014) pp. 142–150]". Soil Dynamics and Earthquake Engineering 71 (aprile 2015): 185. http://dx.doi.org/10.1016/j.soildyn.2015.02.012.

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38

Azizian, A., e R. Popescu. "Finite element simulation of seismically induced retrogressive failure of submarine slopes". Canadian Geotechnical Journal 42, n. 6 (1 dicembre 2005): 1532–47. http://dx.doi.org/10.1139/t05-032.

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Abstract (sommario):

Retrogressive failures have been reported for both offshore and onshore slopes subjected to various triggering mechanisms. As a result of large spatial extension of the failure, the retrogression phenomenon leads to significantly increasing damage and may affect facilities located far away from the original slope. The mechanisms of such failures are not fully understood, and reports of analyses are rather scarce. To simulate earthquake-induced retrogressive submarine slope failures and to better understand the mechanisms involved, the element removal capabilities of a finite element program are used to model a soil mass that fails and then flows away, causing upper parts of the slope to fail retrogressively, as a result of the loss of support. It is explained how an initial failure leads to subsequent failures of a flat seafloor. Effects of a shallow silt layer and of a gently sloping seafloor on the extension of retrogression in a sandy seabed are also studied. It is found that the extension of failure increases significantly because of a gentle seafloor slope and (or) the presence of a silt layer.Key words: retrogressive submarine failure, seismic liquefaction, finite elements.

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Shang, Yanliang, Hongqian Dang, Shuai Huang e Guoqiang Zhang. "Experimental Study on the Settlement Properties of Silt Containing Fine Particles after Liquefaction: Case of Xiong’an New Area of China". International Journal of Geomechanics 21, n. 1 (gennaio 2021): 05020007. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0001864.

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40

Beyzaei, Christine Z., Jonathan D. Bray, Sjoerd van Ballegooy, Misko Cubrinovski e Sarah Bastin. "Depositional environment effects on observed liquefaction performance in silt swamps during the Canterbury earthquake sequence". Soil Dynamics and Earthquake Engineering 107 (aprile 2018): 303–21. http://dx.doi.org/10.1016/j.soildyn.2018.01.035.

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41

Jamali, Hassan, e Ali Tolooiyan. "Effect of Sand Content on the Liquefaction Potential and Post-Earthquake Behaviour of Coode Island Silt". Geotechnical and Geological Engineering 39, n. 1 (10 agosto 2020): 549–63. http://dx.doi.org/10.1007/s10706-020-01512-1.

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42

Ecemis, Nurhan. "Experimental and numerical modeling on the liquefaction potential and ground settlement of silt-interlayered stratified sands". Soil Dynamics and Earthquake Engineering 144 (maggio 2021): 106691. http://dx.doi.org/10.1016/j.soildyn.2021.106691.

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43

Seid-Karbasi, Mahmood, e Peter M. Byrne. "Seismic liquefaction, lateral spreading, and flow slides: a numerical investigation into void redistribution". Canadian Geotechnical Journal 44, n. 7 (1 luglio 2007): 873–90. http://dx.doi.org/10.1139/t07-027.

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Abstract (sommario):

Experience from past earthquakes indicates that seismically induced large lateral spreads and flow slides in alluvial sand deposits have taken place in coastal and river areas in many parts of the world. The ground slope in these slides was often not very steep, gentler than a few percent. Recent research indicates that the presence of low-permeability silt or clay sublayers within the sand deposits is responsible for this behaviour. Such layers form a barrier to upward flow of water associated with earthquake-generated pore pressures. This causes an accumulation of pore water at the base of the layers, resulting in greatly reduced strength and possible slope instability. This paper uses an effective stress coupled stress-flow dynamic analyses procedure to demonstrate the effects of a low-permeability barrier layer on ground deformations from an earthquake event. The analyses show that an expansion zone develops at the base of barrier layers in stratified soil deposits under seismic loading which can greatly reduce shear strength and result in large deformations and flow failure. Without such a layer or layers, the slope may undergo significant displacements, but not a flow slide. Slopes with a barrier layer can be stabilized by drains.Key words: liquefaction, lateral spreads, stratification, flow failure, dynamic analysis, UBCSAND model, drain.

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44

Bensoula, Mohamed, Hanifi Missoum e Karim Bendani. "Critical undrained shear strength of sand-silt mixtures under monotonic loading". Earth Sciences Research Journal 18, n. 2 (16 marzo 2015): 149–56. http://dx.doi.org/10.15446/esrj.v18n2.42492.

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Abstract (sommario):

This study uses experimental triaxial tests with monotonic loading to develop empirical relationships to estimate undrained critical shear strength. The effect of the fines content on undrained shear strength is analyzed for different density states. The parametric analysis indicates that, based on the soil void ratio and fine content properties, the undrained critical shear strength first increases and then decreases as the proportion of fines increases, which demonstrates the influence of fine content on a soil’s vulnerability to liquefaction. A series of monotonic undrained triaxial tests were performed on reconstituted saturated sand-silt mixtures. Beyond 30% fines content, a fraction of the silt participates in the soil’s skeleton chain force. In this context, the concept of the equivalent intergranular void ratio may be an appropriate parameter to express the critical shear strength of the studied soil. This parameter is able to control the undrained shear strength of non-plastic silt and sand mixtures with different densities. ResumenEste estudio utiliza evaluaciones experimentales triaxiales con cargas repetitivas para desarrollar relaciones empíricas y estimar la tensión crítica de corte bajo condiciones no drenadas. El efecto de contenido de finos en la tensión de corte sin drenar se analizó en diferentes estados de densidad. El análisis paramétrico indica que, basado en la porosidad del suelo y las propiedades del material de finos, la tensión de corte sin drenar primero se incrementa y luego decrece mientras la proporción de finos aumenta, lo que demuestra la influencia de contenido de finos en la vulnerabilidad del suelo a la licuación. Una serie de las evaluaciones se realizó en mezclas rehidratadas y saturadas de arena y cieno. Más allá del 30 % de los contenidos finos, una fracción del cieno hace parte principal de la cadena de fuerza del suelo. En este contexto, el concepto de porosidad equivalente intergranular puede ser un parámetro apropiado para expresar la tensión crítica de corte del suelo estudiado. Este parámetro nos permite controlar la tensión de corte sin drenar de cieno no plástico y mezclas de arena de densidades diferentes.

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Du, Guangyin, Han Xia, Jun Cai, Huangsong Pan e Changshen Sun. "Liquefiable Ground Treatment Using Cruciform Section Probe Resonant Compaction Method: A Case Study in the Xitong Expressway, Eastern China". Advances in Civil Engineering 2020 (30 gennaio 2020): 1–11. http://dx.doi.org/10.1155/2020/6564193.

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Abstract (sommario):

The foundation treatment of liquefiable soil has always been an important part of construction. Sand liquefaction decreases the foundation capacity and can cause severe building, highway, or bridge engineering accidents. This study used self-developed cruciform section probe resonant compaction equipment (CSPRCE) to evaluate the applicability and reinforcement effect of the Xitong Expressway foundation. The cone penetration test (CPT) results showed that this soil was liquefiable ground requiring treatment before construction. Laboratory tests illustrated that the clay particle content was nearly 10% in the surface layer, indicating that the traditional resonant compaction probe (RCP) would not provide effective reinforcement; therefore, we adopted the new resonant compaction method (RCM) for the reinforcement process. The CPT and standard penetration test (SPT) results after foundation reinforcement indicated that the cruciform section probe resonant compaction method (CSPRCM) is suitable for treating the Xitong Expressway liquefiable foundation. Before reinforcement, 7-8 liquefiable soil layers were observed, whereas after reinforcement, no foundation testing points were liquefiable. Cone resistance and unit sleeve friction resistance were both improved by a factor of nearly 3 after the CSPRCM reinforcement. The CSPRCM has wider applicability than traditional vibrating compaction methods, especially for sites with a high content of silt and clay particles. The strengthening mechanism of the CSPRCM is a vibration hammer that generates vibrational energy to obliterate the original soil structure and render the sand completely liquefied; the soil particles then rearrange to form a new structure.

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46

Jamali, Hassan, e Ali Tolooiyan. "Correction to: Effect of Sand Content on the Liquefaction Potential and Post-Earthquake Behaviour of Coode Island Silt". Geotechnical and Geological Engineering 39, n. 1 (30 ottobre 2020): 565–66. http://dx.doi.org/10.1007/s10706-020-01609-7.

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47

Ghorbani, Ali, Amin Eslami e Masoumeh Nezhad Moghadam. "Effect of non-plastic silt on liquefaction susceptibility of marine sand by transparent laminar shear box in shaking table". International Journal of Geotechnical Engineering 14, n. 5 (10 gennaio 2020): 514–26. http://dx.doi.org/10.1080/19386362.2020.1712532.

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48

Thevanayagam, S., e T. Shenthan. "Cyclic Pore Pressure Generation, Dissipation and Densification in Granular Mixes". International Journal of Geotechnical Earthquake Engineering 1, n. 1 (gennaio 2010): 42–61. http://dx.doi.org/10.4018/jgee.2010090803.

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Abstract (sommario):

Knowledge of cyclic load induced pore pressure generation, post-liquefaction dissipation and volumetric densification characteristics of sands, silty sands, and silts are important for the analysis of performance of loose saturated granular deposits in seismic areas. This article presents results from an experimental study of these characteristics for such soils containing 0 to 100% non-plastic silt. Pore pressure generation characteristics are studied using undrained cyclic triaxial tests. Pre- and post-liquefaction compressibility and coefficient of consolidation, and post-liquefaction volumetric densification characteristics are determined from consolidation data prior to cyclic tests and pore pressure dissipation tests following undrained cyclic tests. Effects of fines content on these characteristics compared to those of clean sands are examined in the context of intergranular void ratio and intergranular contact density concepts.

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49

Voznesensky, Eugene A., Vladimir Y. Kalachev, Victor T. Trofimov e Victoria V. Kostomarova. "Dynamic instability of seasonally thawing silty soils". Canadian Geotechnical Journal 31, n. 3 (1 giugno 1994): 454–62. http://dx.doi.org/10.1139/t94-053.

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The peculiarities of the dynamic behaviour of silty soils in laboratory experiments that simulate their interaction with gas mining equipment are analyzed. These seasonally thawing soils appear to be very sensitive to dynamic loading and sometimes even liquefaction. Several peculiarities of their dynamic behaviour include: (i) their special sensitivity to very definite and narrow vibration frequency ranges, which vary with grain size and moisture content, and result from the resonant effects in the soil; (ii) the redistribution of pore water during the vibration and subsequent regain; (iii) the thixotropic recovery of the soil after vibration, resulting in the regain of its strength over initial levels, water content and density being constant. Both dilatant and thixotropic effects take place in such soils during dynamic loading, distinguishing them from both clean sands and clayey soils. On the basis of the peculiarities of dynamic behaviour discussed, the authors consider such soils as dilatantly thixotropic dispersed systems. Key words : dynamic properties, soils, thixotropy, liquefaction, resonance, silts.

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Ahmad, Mahmood, Xiao-Wei Tang, Feezan Ahmad e Arshad Jamal. "Assessment of Soil Liquefaction Potential in Kamra, Pakistan". Sustainability 10, n. 11 (15 novembre 2018): 4223. http://dx.doi.org/10.3390/su10114223.

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In seismically active regions, soil liquefaction is a serious geotechnical engineering problem that mainly occurs in saturated granular soils with a shallow groundwater table. Significant seismic hazards are present in Kamra, Pakistan. With the rapid increase in construction in recent years, the evaluation of liquefaction is now considered to be more important for land use planning and development. The intent of this study is to highlight soil liquefaction susceptibility that will eventually support the national authorities in developing guidelines for sustainable development and the mitigation of liquefaction. The typical subsoil profile of Kamra consists of silty gravel (GM) overlain by silty sand (SM), poorly graded sand (SP), and fill layers. Kamra is close to the active Ranja–Khairabad fault with a peak ground acceleration of 0.24g. The river Sehat and the Ghazi Brotha canal pass through the study area. In this study, the soil liquefaction potential in Kamra was assessed at 10 different sites (50 boreholes) by using a stress-based procedure for calculating the factor of safety against soil liquefaction. The results revealed that the middle layers, i.e., poorly graded sand and silty sand in the subsoil profile, are extremely susceptible to liquefaction during earthquakes with magnitudes between 7.5 and 8.0 in Kamra. The correlation between the factor of safety and the equivalent clean-sand-corrected standard penetration test (SPT) blow counts according to the earthquake magnitudes was developed and can also be utilized for areas adjoining Kamra that have the same subsoil profile.

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