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22 December 2015, Volume 29 Issue 6 Previous Issue    Next Issue

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Design and Construction of Double-Ring Bracing System for Deep Excavation in Soft Soils FU Shouyin, JIN Xuelian, GAO Fenfen, ZHOU Yali 2015, 29 (6):  1-4.  Abstract ( 1510 )   Save A deep excavation case history of the Fenghuangxian Commercial Development Project of Zhonghai Group in the Hexi Area of Nanjing City is presented in this paper. The design and construction aspects of this project are introduced. The applications of double ring bracing system in the soft soil and large scale excavation are also discussed. The construction monitoring results indicate that the double ring bracing system can provide a better control in the deep excavation deformation. This method has also the advantage of the earth excavation and the structural construction of the tower buildings. Related Articles | Metrics

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Technical and Cost Analysis of the PHC Piles as Deep Excavation Support in Cohesive Soils LI Jianming1, LIU Qi1, SUN Yongmei2, WANG Zuo1， WEI Hongxing1 2015, 29 (6):  5-8.  Abstract ( 1218 )   Save The conventional supporting system in the vertical excavations in cohesive soil layers is the soldier pile with or without ground anchors. When the cantilever soldier piles are used, larger deformation at the supporting system is expected; If the castinplace soldier pile with ground anchor are used, a long construction period with large investment are anticipated; If the steel pipe piles are used, a large quantities of ground anchor are necessary. This paper present the Prefabricated High Strength Concrete Pipe Pile (PHC) with the ground anchor system for the deep excavation support in the cohesive soil layers. It is technically feasible and has the cost effective advantage.  Related Articles | Metrics

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Design of Soldier Pile and Anchor System for a Deep Excavation SUN Yu 2015, 29 (6):  9-12.  Abstract ( 1217 )   Save A deep excavation is performed near an existing building and the additional surcharge loading exists at the top of the excavation supporting system. A soldier pile and ground anchor system are used to support this excavation in order to ensure the safety of the building and utilities. Related Articles | Metrics

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On Application of Steel Sheet Pile in Deep Excavation Support for a Bridge Foundation LUO Xinwen 2015, 29 (6):  13-15.  Abstract ( 1194 )   Save The deep excavation of Shahe No.1 Bridge foundation was supported by the sheet pile system. This paper introduces the steel waler design and construction techniques. The most important aspects in the entire deep excavation construction are the construction of support system before the excavation and the deformation observation of the supporting structures. Related Articles | Metrics

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Analysis and Mitigation of the Hazards of an Operational Mountain Tunnel Induced by the Deviator Stress LIU Yuancheng 2015, 29 (6):  16-19.  Abstract ( 1293 )   Save The development of the deviator stress induced tunnel hazards could be closely related to the hydrological conditions, design parameters and construction techniques. However, the most important factor that contributing to the tunnel hazards is the magnitude of the deviator stress. Under the sustained high magnitude of the deviator stress, the confining rock mass might develop a progressive failure mode and then induce various related hazards. Therefore, the mechanism of the deviator stress induced tunnel hazards have a special importance. In this paper, in addition to the numerical analysis results, the statistical analysis of the observed tunnel hazard data before and after the tunnel excavation are also conducted. The results indicate that, a tunnel under the high magnitude of deviator stresses might result in creep failure at the stress concentrated area in the lining system. As a result, cracks might be developed in the lining system and the seepage hazards might be induced. Related Articles | Metrics

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Physical Properties of Fly-ash and Blast Furnace Slag Mixtures in the Soil Improvement LIU Xiang, WU Chenglong, XU Youjun, GUO Peng 2015, 29 (6):  20-24.  Abstract ( 1350 )   Save The blast furnace slag and flyash mixtures were used as the foundation fill. The grain size analysis on the mixtures indicates that the fill material is poor graded with the absence of finer grain material. The foundation fill was treated with dynamic compaction as well as the conventional compaction by a vibratory roller. After the treatment, the gradation of the fill materials have significantly improved to the well graded gravel materials. The maximum dry density, optimum moisture and the degree of compaction were obtained by the heavy dynamic penetrometer testing. The average specific gravity of the mixture was obtained from the specific gravity tests on both materials. The code used average specific gravity formula for the mixtures was corrected for the finer grain sized materials. Related Articles | Metrics

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Deep Triaxial Soil-Cement Mixing Columns as a Seepage Cut-off Curtain in the Deep Excavations XIANG Qun 2015, 29 (6):  25-27.  Abstract ( 1220 )   Save This paper presents the studies on the soilcement ratios for the deep triaxial soilcement mixing columns. Under the range of different speeds of the vertical movement of the mixing blades, the optimum soilcement ratio can be obtained through the control of flow rate of the slurry per minute. This technique can be used in the onsite accurate control of the soilcement ratio. The uniformity of the soilcement column can be adjusted by changing the number of and shape of the mixing blades. Related Articles | Metrics

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The Stability Analysis and Mitigation of a Landslide in Liping Village of Jinggangshan City YANG Ting, ZHANG Xu 2015, 29 (6):  28-32.  Abstract ( 1698 )   Save As a common geological hazard, landslides have induced a significant loss of the property and human life and hampered the sustainable development of the economy. This paper present a case history of a landslide in Liping Village of Jinggangshan City. The instability of the slope might cause the loss of more than 50 million RMB, the loss of human life as well as the induced social impact are unmeasurable. This paper systematically analyzed the mechanism and stability of the slope based on the field boring information, laboratory test results and the slope movement monitoring data. Related Articles | Metrics

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Case History of Slope Stability Monitoring in Yi-Ba Expressway GAN Lu1, ZHANG Xiaolun2, JIA Wei2, ZHU Jiebing3, LIU Xiaohong3 2015, 29 (6):  33-38.  Abstract ( 1316 )   Save Landslides and slope instabilities are the common hazards in the construction of highways in the mountain areas. The consequences of the hazards result in not only the economic loss but also adversely affect the construction safety and the construction schedule. The highway slope stability monitoring program for the YiBa highway construction is presented in this paper. The monitored items, technical approach as well as the purpose are introduced. The monitoring results combined with the site visits during the construction, real time slope classification and evaluation, provide a forecast of the potential slope instability and can be used as the assistant to the decision making. The monitoring results can also be used as the criteria for various slope stability mitigation techniques. Related Articles | Metrics

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Application of CPTU in the Marine Geotechnical Investigation in Qiongzhou Strait ZHAO Qinglong1, DONG Zhijun1, SHEN Jianhua2 2015, 29 (6):  39-43.  Abstract ( 1324 )   Save The cone penetration test with pore pressure measurement (CPTU) has been widely used in geotechnical investigation under various conditions due to its advantages of simple and fast operation, providing continuous and repetitive data. With the increasing demand of marine resource utilization, the CPTU receives wider applications in the marine geotechnical investigation. This paper presents a case history of geotechnical investigation for an undersea tunnel alignment project across the Qiongzhou Strait. The evaluation methods of marine soil stratigraphy, shear strength of cohesive and the liquefaction of loose sand are presented and compared with other conventional field and laboratory test results. The results indicate that the application of CPTU in the marine geotechnical investigation has the characteristics of better reliability. Evaluation methods and the empirical relationships used in the case history can also be used in similar marine environment. Related Articles | Metrics

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Ultimate Capacity Analysis of a Single Circular Hole and Its Shear Strain Development FANG Haoliang， WANG Liang 2015, 29 (6):  44-47.  Abstract ( 949 )   Save The numerical analytical model of the ultimate capacity of a single circular hole is established on the geophysical and geotechnical investigation results for a large refinery project. The progressive failure mode is studied by the stepped incremental loadings with the consideration of the interactions of foundation structures, overburden soils and the thickness of the karst rock at the dome. The incremental shear strain plots under the correspondent incremental loadings are also provided and the progressive failure process of the circular hole can be explicitly demonstrated. Related Articles | Metrics

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Mechanical Parameters and Hydraulic Fracturing Physical Modeling of Shelly Limestone of Daanzhai Formation WU Leize, LI Yuanzhao, LIU Long, HUANG Xiaokai, WANG Qianwen 2015, 29 (6):  48-53.  Abstract ( 1516 )   Save The shelly limestone reservoir of commercial oil and gas wells are found in the Sichuan Basin, but the production capacity is relatively low. The full size rock cores from the pilot well Jiaoye 32HF and from the storage layer rock outcrops were used for the studies. The studies include microscopic structures, mechanical properties and hydraulic fracturing physical modeling. The test results indicate that, 1) both the primary and the secondary fissures of the shelly limestone are well developed with the porosity ranging from 0.04% to 1.4% with an average of 1.4%. 2) A weak heterogeneous is observed in the vertical and horizontal joints of the shelly limestone; an obvious brittle property exists in the uniaxial compressive test of the intact rock cores. The heterogeneous property in the rock layers will be beneficial to the development and the expansion of the compressive cracks. 3) In the triaxial tests, the strength and the stiffness of the intact rock samples increase with the confining pressures. The brittle failure mode is gradually changed to the ductile failure mode. 4) After the compressive failure, cracks are developed in the direction that perpendicular to the minor principal stress. These compressive cracks can be connected with the nature fissures and these connected fissures can improve the oil/gas productivities. Related Articles | Metrics

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Groundwater Value for the Buoyancy Design in the First Terrace of Yangtze River in Wuhan LIU Yazhou1, ZHANG Xiaoyu2 2015, 29 (6):  54-58.  Abstract ( 1657 )   Save The subsurface condition of the first terrace of Yangtze River in Wuhan has a distinct two-layer structure. The surface water is well connected with the groundwater at areas close to the river. As a result, the buoyancy design of the structures in these areas are associated with the groundwater level, foundation embedment depth, subsurface conditions below the foundation as well as the historical groundwater levels in the area. The future maximum flood water level after the Three Gorges Project construction is critical to the buoyancy design. This paper presents the results of the buoyancy design under various groundwater levels and different foundation embedment depths. Related Articles | Metrics

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Pre-stress Changes in the Pre-stressed Anchors for the Slope Stability LI Fangzhen1,2, LIU Kan1,2, HUANG Yuluan2, CHEN Ruiming1,2 2015, 29 (6):  59-62.  Abstract ( 1543 )   Save This paper presents a case history of the monitoring and data analysis of the prestressed ground anchors for a slope stability remediation project. The data indicates that the prestress loss can be divided into three stages: Fast prestress loss, gradual loss and relative stable. The influence factors that affecting the stress loss have been summarized. The project results indicates that the prestress monitoring can provide the real time information about the deformation of the slope and the monitoring plays a critical role in the slope stability analysis as well as the mitigation.\= Related Articles | Metrics

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Evaluation of the Borehole Quality in the Geotechnical Investigation by BP Neural Network Process MING Qianjun, YAO Yueliang, ZHANG Jie 2015, 29 (6):  63-66.  Abstract ( 1431 )   Save The quantitative evaluation of the borehole quality in the geotechnical investigation is a comprehensive system that involves multitargets, multiactors and multilayers. Based on the summary of the boring information evaluation by the conventional methods, a comprehensive borehole quality evaluation system is established by using the Back Propagation (BP) neural Network Process. This system can provide a better nonlinear and complicated relationships between the borehole quality results and the involved factors. This system can also minimize the subjectively biased evaluation results. As an example this BP model is used in a practical borehole evaluation project. The results indicate the application of this model is feasible. Related Articles | Metrics

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Karst Collapse Simulation by Using Interface Mechanics PAN Ke1, YU Mengze2 2015, 29 (6):  67-71.  Abstract ( 1385 )   Save The interface mechanics theory was used in the numerical simulation of the process of karst rock cavern collapse in the soil, rock and void system. It is concluded that the interface had a significant influence on the subsidence in the karst geotechnical materials. A stress concentration and the stress discontinuity are encountered at the interface between the soil cavity and the void. And the progressive failure was initiated at the interface of soft soil-rock. These numerical analysis results are consistent with a collapse encountered in the Guixng Development. Related Articles | Metrics

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Effect of Rock Mass Shear Dilatancy on the Ultimate Axial Capacity of Tunnel Anchorage XIA Guobang1， ZHANG Shuihua1, DENG Qin2 2015, 29 (6):  72-74.  Abstract ( 1475 )   Save The effect of the dilatant angle on the ultimate axial uplift capacity of the tunnel anchorage is analyzed by the finite element method (FEM) with overloading. The results indicate that, the anchorage zone of influence in the rock mass increases with the value of the shear dilatant angle. The axial uplift capacity difference could be twice of the magnitude with different shear dialatant angles. It is recommended that the shear dilatancy should be appropriately considered in the estimation of the ultimate axial uplift capacity of the tunnel anchorage. Related Articles | Metrics

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Numerical Analysis of the Response of Pile Foundation under Coupled Loads ZHANG Chen1， CHEN Feng1,2, CHEN Sanshan3 2015, 29 (6):  75-79.  Abstract ( 1453 )   Save The response of the pile foundation under the vertical and cyclic horizontal loads was simulated with a commercial finite element software PLAXIS. The results indicate that, when the vertical load is less than a critical value, the horizontal displacement at the pile head decreases with the increase of the vertical load. When the vertical load exceeds the critical value, the lateral response at the pile head increases with the vertical load. For piles with a relative low strength, the vertical load is a major factor that influence the lateral deflection of the piles. A reverse deflection curve will be developed if the cyclic lateral loads are acting on a pile with large vertical load. Related Articles | Metrics

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Testing Methods for the Soils Improved By the Dynamic Compaction CHEN Daosong, CUI Wei, QIU Zhiwen 2015, 29 (6):  80-82.  Abstract ( 1503 )   Save This paper presents case histories of foundation soil testing on the dynamic compaction treated soils. Several testing methods were used to evaluate the properties of the treated soil: soil laboratory testing, plate loading testing; and heavy dynamic penetrometer testing. The tested soils can be divided into two layers: upper (within 3 times of the plate width) and lower layers throughout the relationship between the bearing capacity and the dynamic penetrometer blow counts as well as the relationship between the compression modulus and the dynamic penetrometer blow counts. The two layers can be separately evaluated so that the weak layer can be identified and mitigated. Related Articles | Metrics

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The State-of-the-Art of Studies on Contaminated Soils ZHANG Qin， ZHANG Qihang， ZHANG Yudong， XIAO Yulong， HAN Junming 2015, 29 (6):  83-85.  Abstract ( 1333 )   Save With the rapid development of economy in China, the contaminated soil is becoming a typical geoenvironmental engineering topic. Based on the extensive investigations, this paper presents the research status contaminated soils: the mechanism for the property changes; comparative study of different types of contaminated soils. The paper also presents the different remediation techniques:  biological, physical and chemical as well as combined remediation methods. Related Articles | Metrics

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Feasibility of the Application of Ram Compacted Columns with Enlarged Base in Suzhou TANG Chao1, YUAN Yuntao1,2, LI Suchun1, HAN Shuang1, LU Ruiwu2 2015, 29 (6):  86-88.  Abstract ( 1419 )   Save The selection of pile/column types is critical to the project cost control. The physical and mechanical properties of the shallowly deposited Quaternary soils in Suzhou area are statistically analyzed. The properties of the bearing strata that are potentially suitable for the ramcompacted columns with enlarged base are summarized. A cost comparisons of the ramcompacted columns with enlarged base is provided for the various practical projects. It is concluded that the application of the ramcompacted columns with enlarged base in the Suzhou area is feasible. Related Articles | Metrics

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Plate Loading Tests for Dynamic Compaction Improved Soils LIU Qin1, 2 2015, 29 (6):  89-92.  Abstract ( 1272 )   Save The soil improvement is necessary when the shallow weak soils could not meet the bearing capacity requirements of the proposed building structures. This paper presents a cased history of the dynamic compaction treatment of the proposed Toll Collection Administration building of Yanhai Expressway. A total of four locations in the dynamic treatment area were selected for the static plate loading tests and the loadingsettlement curves (ps) were obtained. The test results indicate that all the ps curves are gradual change type and no abrupt failure point could be identified. In all test curves, very small rebound could be observed during the unloading. The bearing capacity of the treated soils at test each location is therefore determined from the settlement magnitude and plate dimension ratio and the overall bearing capacity of the entire foundation is the averages bearing capacity values determined from the ps curves. The test results also indicate that the dynamic compaction method is also a viable soil improvement tool and the plate loading test can be used in the evaluation of the bearing capacity of the treated grounds. Related Articles | Metrics

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The Correlative Study between the Point Load and Uniaxial Compressive Strength of the Weathered Granite in Tianjin Pan Mountain Area ZHOU Changrui, XU Yuan, MU Lei 2015, 29 (6):  93-95.  Abstract ( 1525 )   Save Both the point load and the uniaxial compressive tests are conducted on the strongly weathered granite rock samples from a project site in Panshan District, Tianjin City. The parameters in calculating the point load strength are studied in the tests. The method in the current design code of estimating the uniaxial compressive strength from the point load values is discussed and the correlations between the point load test results and the uniaxial compressive strength values are developed. Related Articles | Metrics

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Remediation of Highway Embankment Collapses and Deformation Monitoring WANG Xinguo, WANG Jiaqiang, LI Dapeng  2015, 29 (6):  96-101.  Abstract ( 1572 )   Save Mass collapses are one of the most common hazards in the mountain areas. For highway embankment collapses, the pressure grouting and the dynamic compaction are the most common remediation methods. This paper presents a case history of the highway embankment collapse at Ergangqiao of MianMao Highway. The collapse body was back analyzed with strength parameters obtained from the insitu tests. The strength and deformation of the dynamic compaction treated embankment are estimated. The settlements on the highway during and after the construction are monitored by using different monitoring methods in order provide a satisfactory remediated embankment that carrying the highway operational live loads. Related Articles | Metrics