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20 August 2015, Volume 29 Issue 4 Previous Issue    Next Issue

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Deep Excavation Supports with the Combination of Soil Nailed Wall and Ground Anchor WANG Yong1,2, WANG Zong1,2， WANG Dong1,2 2015, 29 (4):  1-3.  Abstract ( 1245 )   Save The trend of the deep excavation support is turning from the single method to a combination of different methods. In the engineering practice, meeting the objective of the cost effective, technical feasibility, and environmental safety leads to the new combination of deep excavation support: soil nailed wall for the upper support and the ground anchor for the lower portion of excavation support. This paper present a deep excavation case history in Xingtai City. The combination of soil nailed wall and the ground anchor method is proved to be very effective, the ground subsidence is smaller than that of the similar excavation elsewhere. The computed settlement results are consistent with the observed values. Related Articles | Metrics

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Design Calculations of a Pile and Ground Anchor System in the Deep Excavation Support DONG Yong， HE Lihong 2015, 29 (4):  4-8.  Abstract ( 1250 )   Save This paper presents a case history of design calculation for the pile and ground anchor system in the deep excavation support of a large underpass project. The pile and round anchor system was selected based on the comparison of several feasible supporting schemes. The design calculations discuss the different design models and the requirements of the ground anchors. Related Articles | Metrics

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Deep Excavation Supported by the Flexible Wall and the Pre-stressed Ground Anchors ZHANG Changju, CHEN Wei, MOU Dapeng 2015, 29 (4):  9-12.  Abstract ( 1352 )   Save This paper presents a case history of deep excavation support in silty sand soils by using a flexible retaining wall with prestressed ground anchors. The seepage stability and retaining wall strength aspects of the flexible wall are examined and the role of the ground anchor in the dewatering is also discussed. The design of flexible wall and the ground anchors are also verified by the project monitored data. This project also demonstrates the advantages of the cost effectiveness and the construction schedule of the flexible wall with prestressed ground anchors. Related Articles | Metrics

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Structural Capacity of the Inclined Supporting System and Soil Stress in the Deep Excavation LIN Guowei1, ZUO Renyu1, LU Zhao2, ZHAI Dongge2, LU Zhenwen3 2015, 29 (4):  13-18.  Abstract ( 1509 )   Save The inclined supporting system has received more and more applications in the large deep excavation projects. This paper presents the numerical analysis results of an inclined support system with pile cap by using commercial software ABAQUS. The results of the inclined supporting system are also compared with the results of the conventional horizontal strut system. The stresses in the two different supporting system are analyzed. Further, the stresses in the soil mass, ground subsidence, the bottom heave as well as the lateral deflection of the pile are also compared in details. The mechanism of the inclined structures and the advantages of this system in the control of the pile lateral deflection and the ground subsidence are also presented. Related Articles | Metrics

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Large Diameter Rotary Drilled Cast-in-Place Concrete Piles in Karst Rock Formations LEI Yizhong 2015, 29 (4):  19-22.  Abstract ( 1349 )   Save This paper presents the rotary drilled, castinplace concrete pile installation techniques in the complicated karst rock formations. The common quality hazard during the pile installation and their remediation measures are discussed with an aim of improvement quality and efficiency of the concrete piles in karst formations. Related Articles | Metrics

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Construction Techniques of Mass Concrete Foundation in Complex Geological Conditions LIU Yuan1,2, ZHANG Keneng1, LIU Chuang1, XIAO Xiaoling2 2015, 29 (4):  23-26.  Abstract ( 1377 )   Save The mass concrete foundation construction techniques in the complex geological conditions are introduced through a case history of the vibration isolation foundation installation. During the construction, the treatment of adverse conditions such as, karst rock cavities and pinnacles; rock blasting; deep excavation support; dewatering and mass concrete pouring; etc. are encountered. The mass construction installation issue in the complex geological conditions is resolved through the proper selection of concrete materials, watercement ratio and the proper curing method. Related Articles | Metrics

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Application of Steel Sleeve Balance Combined with Ground Freezing Methods in Shield Launching Under the Large Embedded Depth and High Artesian Water Pressures ZHENG Guanghui 2015, 29 (4):  27-31.  Abstract ( 1508 )   Save This paper presents the shield launching results of the first phase project of Wuhan Rail Transit No. 3 Line between Hongkong Road and Huiji Road. The shielded excavation has the characteristics of large embedment depth and high artesian water pressures in the first terrace of Yangtze River. By using the combination of the steel sleeve balance and the ground freezing methods, the shield launching in these complicated geological condition was successful. The project practice indicates that the safety of the construction can be secured by using the combination of the steel sleeve balance and the ground freezing methods and this technique can be used in the launching of the shielded excavation in similar geological conditions. Related Articles | Metrics

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Applications of TBM Liner Sealing Ring and Outer Displacement Stopper MA Cheng1, SUN Shiying2, SUI Shijun2, XIN Fengmao2, ZHANG Yuelin2 2015, 29 (4):  32-34.  Abstract ( 1398 )   Save A number of innovative tunnel grouting techniques are introduced in the double shielded TBM excavation of Daban Water Tunnel in accordance with the site specific engineering and geological conditions. The liner longitudinal outer displacement stopper, pea gravel backfill grouting for the sealing rings as well as the consolidation grout by using perforated steel grouting pipes are used in the tunnel excavation support. These techniques are based on the characteristics of the large cross section hexagonal liner, pea gravel backfill grouting in the tunnel supporting structures as well as the comprehensive analysis of the construction monitoring data. These techniques significantly improve the excessive displacement of the side liners, lack of required compaction in the pea gravel grouting as well as the problems in the supporting of weak surrounding rock mass during the double shielded tunnel construction. Related Articles | Metrics

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Construction Techniques of Tunnels in Cold Region WANG Miao1， SONG Gang2 2015, 29 (4):  35-39.  Abstract ( 1718 )   Save Tunnel constructions in the cold regions frequently encounter the frozen hazard due to the low temperature and the presence of water. During the design process, well drained and warm temperature retention are two key aspects. The low temperature tunnel construction techniques are studied in the Ningcan Tunnel of Qinghai Province. Both numerical analysis and analogy of the similar project methods are used in the determination of the warm temperature retention length, thickness of temperature isolation, installation as well as selection of the temperature isolation material are studied. The research results can be used for the construction of tunnel in the cold regions. Related Articles | Metrics

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Remediation Design of Landslides near the City Expressway LIU Dong1,2 2015, 29 (4):  40-43.  Abstract ( 1440 )   Save Landslides on the slopes at both sides of the city expressway might have a significant impact on the safe operation of the roadway. It is therefore urgent to provide protective measures for areas that have landslide hazard potentials and provide mitigation measures for areas that have slides occurred. This paper provides a case history of landslides at a city expressway in South China. The characteristics of the landslide projects are introduced and the key aspects of the mitigations are proposed. The landslide process was simulated with the finite element method. The numerical analysis indicates that the landslide mitigation method is effective and the safety hazard to the roadway has been eliminated. Related Articles | Metrics

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Stability Analysis of a Syncline Rock Slope and It Mitigation Measures ZHAO Yejiang1,2 2015, 29 (4):  44-47.  Abstract ( 1519 )   Save This paper briefly introduced the topographic, geologic conditions, engineering and hydrological geology aspects of a syncline rock slope in Guiyang City. The stability aspects of this slope are also qualitatively and quantitatively evaluated and the parameters for the slope stability analysis are appropriately determined. In order to evaluate the effect of buildings at the crest of the slope on the stability, the syncline slope after the excavation is analyzed with planar sliding method. The supporting scheme is selected based on the engineering conditions and construction costs comparison of each measure. Related Articles | Metrics

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Impact of Soil Parameters on the Expansion Pressure in the Pile Installation CAO Xiujuan 2015, 29 (4):  48-50.  Abstract ( 967 )   Save This paper presents the analytical solutions of the maximum squeeze pressure and the maximum expansion pressure in soil during the pile installation. The solutions are derived based on the soil plasticity, the structural damage as well as the influence of the vertical direction. The impact of the soil parameters such as, soil cohesion, internal friction angle, elastic modulus and Poisson’s ratio on the limit expansion pressure as well as radius of the plastic zone during the pile installation are investigated. The results indicated that the Poisson’s ratio has no impact on the limit expansion pressure and the other parameters have impact. This analytical solution provides the soil movement mechanism during the pile installation and provides guidelines for the pile installation. Related Articles | Metrics

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Numerical Analysis of Ground Anchor and Soldier Pile System for a Deep Excavation under Surcharge DING Wei1, WANG Xiujiao1, LI Chenyan1, ZHU Changzhi2 2015, 29 (4):  51-53.  Abstract ( 1374 )   Save This paper presents the finite difference analysis results of the soldier pileground anchor system under the ground surcharge loading conditions by using FLAC3D. The horizontal deflection and the bending moment in the supporting system are analyzed under different strength values of the structure and the supporting positions. The results indicate that, with a fixed location, the horizontal deflection increase with an increase of the surcharge load magnitude. The maximum horizontal deflection presents at 1/3H (H is the total exposed excavation height). The bending moment along the soldier pile is first increasing with depth and then decreasing. The location of the maximum bending moment is near the bottom of the excavation. Under a fixed surcharge loading magnitude, if the surcharge is acting beyond a distance of the excavation height H, there is not impact of the deflection of the supporting structures. The maximum impact of the surcharge loading on the maximum magnitude of bending moment in the supporting structure is between a distance of 0.4H and 0.7H. Related Articles | Metrics

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Finite Element Analysis of CFG Columns for a Residential Community in Xianyang ZHANG Jing1, SHI Bin1, YANG Xinlong2 2015, 29 (4):  54-56.  Abstract ( 1504 )   Save The CementFly AshGravel (CFG) columns are widely used as the composite foundations in the building industry: multiple, high raised and super high raised buildings and industrial factories. Although this technique is proved to be cost effective with good engineering results, the theoretical aspects of the CFG method and its design methodology are still to be completed. It has a significant practical importance to conduct research work in the performance of the CFG columns. A threedimensional finite element model of single column under axial symmetric loading condition by using ABAQUS is established and the results are compared with the insitu static loading test results. The deviations between the simulated and the observed results are also discussed. Related Articles | Metrics

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Characteristics of Post Grouted Pile Group with High Pile Caps DENG Yousheng， HE Shaohua 2015, 29 (4):  57-60.  Abstract ( 1412 )   Save This paper presents the numerical analysis of the post grouted pile groups in a marine highway bridge project by using software ADINA. The three-dimensional finite element models were used to analyze 9 pile groups before and after the post grout treatment. The load transfer characteristics of the pile, axial stresses in the pile and within the pile group as well as the displacement of the pile group are evaluated. The results indicates that, the post grouted pile can reduce the pile group settlement by 44.3% as well as improve the stress distribution. Related Articles | Metrics

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Deep Excavation Deflection Prediction Using on BP and ARX Models LI Shangqin， LUO Wuzhang， CHEN Xiongtu, TANG Fengqiang 2015, 29 (4):  61-64.  Abstract ( 1784 )   Save With the development of data collection, transfer and the requirement of safety in the construction, the deflection monitoring of the deep excavation becomes an integral part of the design as well as construction. The neural network approach through Back Propagation (BP) model and Auto Regressive with eXtra Input Signal (ARX) model has been applied in the deep excavation deflection monitoring and prediction. The results indicate that both models can satisfactorily predict the construction deflections. However, from the mean square error point view, BP has a better prediction results compared with the predictions made by ARX model. Related Articles | Metrics

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Karst Development Features and Foundation Engineering Design in Offshore of Dalian City LIU Lin, LIU Xiaopeng, WANG Yuling, LIU Liansheng 2015, 29 (4):  65-68.  Abstract ( 1357 )   Save The engineering developments in the nearshore Dalian area indicate that the karst conditions of nearshore area consist of rock pinnacles and fissure like cavities with the dipping in the vertical directions. The tectonic folding and alternating of mudstone are the main contributions to the karst rock characteristics. In the rocksocketed pile design practice, appropriate thickness above the karst cavern with different dimensions is critical to the safety. Gravity foundations require adequate cushion thickness and the rock pinnacles should be removed to minimize the stress concentration. Soft soils in the rock pinnacles need to be removed and appropriate compaction is necessary for the foundation construction. Related Articles | Metrics

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Back Analysis of the Shearing Strength of Red Clay Slopes WANG Chengchun 2015, 29 (4):  69-72.  Abstract ( 1669 )   Save This paper presents the results of a creeped red clay slope triggered by the rainfall. The soil parameters were determined by the fast shear testing. The soil slope was back analyzed by the residual thrust method. Slope with both global shear failure plane and segmented shear plane were considered since the slope might be homogeneous and heterogeneous. The back analysis results indicate that shear strength parameters obtained by the fast shear testing are appropriate. Further, due to the characteristics of the red clay slopes, the precipitation has an important impact on the development of the shear plane. The shallow failure mode is then developed and it is proved this mode is reasonable. Related Articles | Metrics

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Applications of AutoCAD Civil 3D in Landslide Hazard Warnings and Mitigations ZHANG Jianzhong1, LIAN Jiangbo1， LIU Faxiang2 2015, 29 (4):  73-76.  Abstract ( 1726 )   Save AutoCAD Civil 3D is a popular civil engineering software with powerful threedimensional modeling for the computer aided design. This paper presents a case history of using this software in the excavation of a high syncline cut slope in Guanling Formation in Guizhou area. The AutoCAD Civil 3D was used in modeling the complicated 3D geological conditions. The weak zones in the soil/rock mass would be able to be identified and mechanical parameters of the weak zone were back analyzed. As a conclusion, this software was successfully provide the guidance in the cut slope design and construction and provided an early warning for the potential landslide hazard. Related Articles | Metrics

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High Cut Slope Safety Hazard Prediction Using Fuzzy Analytic Hierarchy Process Method CHENG Zhengchuan， LUO Fake 2015, 29 (4):  77-80.  Abstract ( 1584 )   Save This paper presents the hazard evaluation results of three excavation slopes for Buildings #7, #8 and #9 in a residential development in Huangshanchong of Guiyang City. The safety hazard and its influence factors of these high cut slopes are evaluated by a combination of Expert Investigation Method and Confidence Index Method. The engineering safety hazard model for urban high cut slopes is established and the model is evaluated with the Analytic Hierarchy Process (AHP) as well as Fuzzy Comprehensive Evaluation (FCE). The safety level of these slopes are obtained and the risk management recommendations are proposed. Related Articles | Metrics

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Impact of the Weak Rock Zones on the Excavation of a Deeply Buried Tunnel ZHANG Qifeng1， ZHANG Chuanqing2， ZHOU Hui2, LI Zhen2 2015, 29 (4):  81-85.  Abstract ( 1815 )   Save This paper presents the numerical analysis as well as theoretical analysis results of stability of a tunnel in the rock mass with weak rock interlayer. The coupled elasticplastic model of marble considering confining pressure effect and the perfect elastoplastic model of the chlorite schist based on MohrCoulomb criterion are adopted in the analysis. The major results are: 1) when the excavation reaches the rock mass containing weak zones, the weak rock will be intruded in a progressive failure mode and a large plastic zone is formed immediately behind the excavation face, whereas, the stability of the rock mass in front of the excavated face is not significantly affected; 2) the thickness of the weak zone has a large influence on the plastic zone of the weak zone but it has limited impact on the stability of the rock mass behind as well as in front of the excavation; 3) If multiple weak rock zones are encountered in the tunnel excavation, the time required to reach the plastic zones in the weak rock zones will be the same as the time needed in a single weak zone is encountered. The plastic zone can also be found in surrounding rock mass with better engineering properties. Related Articles | Metrics

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Study on Engineering Geology and Engineering Measures for the Red Clay of Cretaceous Age in Area between Nancheng and Guangchang Basin of YingMei Railway FAN Guofeng 2015, 29 (4):  86-89.  Abstract ( 1333 )   Save Comparing with the other frequently encountered soils, the Red Clay of Cretaceous Age has distinct properties due to its differences in degree of cementation, structural fabric and sedimentary formations. This paper presents the geological engineering properties of the area between Nancheng and Changguang Basin of MeiYing railway based on the engineering geological survey, insitu as well as laboratory test results. The properties of the Red Clay formation have summarized into three aspects. The railway construction recommendations are also proposed in the paper. Related Articles | Metrics

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Karst Sinkhole Hazard Evaluation of Zhaoqing City, Pearl River Delta WANG Zhongzhong 2015, 29 (4):  90-93.  Abstract ( 1575 )   Save Sinkhole is one of the major geological hazards in Quaternary Soils that covering Zhaoqing, a city in the west Pearl River Delta area. This paper summarizes three typical sinkhole collapse modes based on the observed sinkholes in the Zhaoqing City as well as the geological conditions. The entire karst area is divided into 7092 grids as the evaluation units. In each unit, the soil and rock strata; degree of karst development; groundwater activities as well as the tectonic structure are factored. The likelihood of the sinkhole collapses are evaluated by using a comprehensive indices. Related Articles | Metrics

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Engineering Aspects of Yuxi Regulation Gate in Chaohu, Anhui Province WANG Zhiyong 2015, 29 (4):  94-97.  Abstract ( 1290 )   Save The Yuxi Hydraulic Regulation Gate is suffering excessing settlement under various loading conditions. The natural conditions, hydraulic, geological tectonic structure, seismic and geotechnical conditions at the site are reviewed. The physical and mechanical properties underneath the gate have been evaluated. The seepage stability is mainly represented by the piping stability. Under the seepage loading conditions, the soil particles, fabric and structures might have deformed and therefore, lead to the seepage related displacement or failure. The evaluation eliminates the potential of liquefaction under the seismic conditions. The scour conditions on the stabilities of the riverbed channel and the hydraulic structures are also important. The foundation remediation plan was proposed based on the stability evaluations. The adopted solutions are: concrete pipe pile installation on the water; seepage path increase and installation of riprap rocks. Related Articles | Metrics

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Parameters Zoning Back Analysis of Surrounding Rock Mass Underground Caverns Li Xiyong1， Feng Ling1， Liu Shangge2 2015, 29 (4):  98-102.  Abstract ( 1677 )   Save When an underground engineering opening is excavated, a zone of disturbance in the surrounding rock mass will be formed due to the unloading effect, blasting vibration and other construction activities. Different zones might have different influence when the back analysis id performed and this different influence should be considered. Zoning back analysis method for the rock mass design parameters is proposed based on the different degrees of rock mass disturbance in underground caverns. A case of providing the rock mass parameters for Gongguoqiao Hydraulic Electricity project is presented in this paper. The cross sectional construction monitoring for the underground rock cavern was used for the back analysis. The back calculated rock parameters were used in the finite element analysis. It is concluded that the deformations of the calculated are within 7% of the observed values. Related Articles | Metrics

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Felicity Effect of Sandstone under Cycling Loading Conditions TANG Xiaojun1,2, YAN Bing1, XU Jiang2 2015, 29 (4):  103-106.  Abstract ( 1034 )   Save This paper presents the experimental study results of the state variables, physical parameters and acoustic emission properties of sandstone samples under various cyclic loading levels. The results indicate that, 1) under loadingunloading conditions, the amount of plastic strain increases with the increase of loading level; 2) distinct acoustic emissions are observed during the fissure closing period in the loading stage and no acoustic emissions are observed during the unloading stage; 3) Distinct Felicity Effect is encountered in both loading and unloading conditions. Different Felicity Effects are found in different stress levels. A lower stress level usually contributes a higher Felicity Effect. With the increase of the stress level, the state variables and the physical parameters demonstrate a trend of increase. Related Articles | Metrics

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Determination the Shear Strength Parameters of Rock Mass through the Least Absolute Linear Regression on Symmetric Triangular Fuzzy Numbers CHEN Zhibo 2015, 29 (4):  107-109.  Abstract ( 1191 )   Save The shear strength parameters of rock mass have the characteristics of randomness of fuzziness. This paper presents an approach of determination of the rock mass shear strength zone based on symmetric triangular fuzzy numbers. The rock strength parameters are determined through the least absolute linear regression. This method not only can reflect the uncertainty of the shear strength parameter, it but also can reduce the impact of abnormal data on the data fitting results. This new approach has the advantage of simple calculation and easy to use. A case history of rock mass shear strength parameters determination is presented in the paper. Related Articles | Metrics

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Determination of Parameters for Davidenkov Constitutive relations Model for Wuhan Silty Soils and Implementation of ABAQUS Software ZHAO Xuqing 2015, 29 (4):  110-115.  Abstract ( 1503 )   Save This paper presents the resonant column test results on Wuhan Silty soil samples. The relationships between the dynamic shear modulus, G; damping ratio, μ; dynamic shear modulus ratio, G/Gmax and the dynamic shear strain are obtained throughout the tests. The parameters that describe the Davidenkov skeleton curve are obtained through the test data fitting method. The subroutine module for the dynamic elasticplastic constitutive model is developed and is implemented into a two dimensional ABAQUS numerical model for nonlinear seismic reaction of silty soils. Related Articles | Metrics

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Progress in Image Processing Method for Soil Cracks XIAO Mingming1, LIU Guanshi2, CHEN Yonggui1 2015, 29 (4):  115-118.  Abstract ( 1195 )   Save This paper reviews the developments of the mathematical morphology and image segmentation in the processing of the crack in the soil mass. In the area of mathematical morphology, the development of the noise filtering, skeleton extraction and reconstruction methods are described; in the area of image segmentation, the methods based on the threshold, edge detection, clustering and zoning are introduced. Finally, the prospects of these image processing methods are discussed. Related Articles | Metrics

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Experimental Tests of the hear Dilatancy of Guangzhou Structural Silty Clay ZHANG Pei1, YANG Xueqiang1, ZHANG Xintao2 2015, 29 (4):  119-123.  Abstract ( 1710 )   Save This paper presents the laboratory test results of the consolidation test using the high pressure consolidation equipment and the consolidated, undrained shear test using true triaxial shear test equipment on the undisturbed Guangzhou silty clay.  The relationship between the shear dialatancy, d , and the stress ratio, η , is plotted based on the test results. This paper also discusses the impact of intermediate principal stress ratio, bσ , and the angle, α between the major principal stress and the direction of sedimentation on the shear dilatancy of the soil mass. The test results indicates that the dilatancu of the soil mass decreases with the increase of the bσ(intermediate principal stress ratio) and the α (angle between the major principal stress and direction of sedimentation). The structural properties of the soil such as the heterogeneous and factors triggering the heterogeneous properties of soil mass affect the shear dilatancy as well as the shear strength. Related Articles | Metrics

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Coefficient of At Rest Earth Pressure of Collapsible Loess NIU Junxian, XIE Duoling 2015, 29 (4):  124-126.  Abstract ( 1214 )   Save This paper discusses the laboratory test methods of the coefficient of at rest earth pressure. The feasibility of at rest earth pressure test on the saturation treated collapsible loess is analyzed. The paper also summarizes the testing curves and the static at rest earth pressure coefficient can be obtained from the linear curve fitting method. Related Articles | Metrics

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Geotechnical Investigations for the Liuzhuang Mine Main Shaft Excavation with Ground Freezing CHENG Shaoqing 2015, 29 (4):  127-129.  Abstract ( 1059 )   Save The geotechnical investigations were conducted on the Liuzhuang Mine main shaft tower ground freezing excavation site before and after the ground freezing when the ground was completely thawed. Different test methods were applied at the site and changes of the soil properties before and after the ground freezing were compared.   Related Articles | Metrics

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A Case History of the Pile-Supported Raft Design Optimization LI Qiannan1, ZHANG Li2 2015, 29 (4):  130-134.  Abstract ( 1009 )   Save This paper presents a case history of the basement improvement design for a High-Raised Building: International Trade Center in Wuhan. The owner, Wuhan Hanpeng Real Estate Development Co., contacted the Soils and Foundations Committee of Hubei Society of Civil Engineers in 1993. The targeted tasks were: 1) Reduce the thickness of the foundation slab; 2) Raise the bottom of foundation slab elevation; and 3) optimize the other structural elements in the basement design to facilitate the safety, to reduce the cost and for the ease of the construction. The Soils and Foundations Committee fulfilled the requirement of the owner.  Related Articles | Metrics