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20 December 2011, Volume 25 Issue 6 Previous Issue    Next Issue

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The Effect of Buildings at the Slope Crest on a Roadway at the Toe LIU Yong liang1, LIU Yong li2, PENG Xiao mao1, WU Jian liang1 2011, 25 (6):  1.  Abstract ( 2464 )   Save A proposed low\|rent housing community is at the crest of a slope with a highway at the toe. The stability of the slope is therefore very important to the buildings as well as to the roadway. The safety factors of the slope under both moist and saturated conditions are back\|calculated. It is concluded that the height of the slope could not exceed 10 meters. The effect of load magnitudes and loading locations to the edge of the slope has been thoroughly investigated. When a shallow foundation is proposed, slope instability will likely occur when the footing pressure is greater than 150 kPa. The impact of the building load on the slope is minimal when the distance is greater than 8 meter away from the edge of the slope. Related Articles | Metrics

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Numerical Simulation on the Construction and Excavation Process of the High Inlet  Slope of a Diversion Tunnel in Zhexi Hydropower Station Extension Project CHENG Ye1, CAO Wen gui2, XIE Jin rong1 2011, 25 (6):  4.  Abstract ( 2683 )   Save The geologic condition of the high inlet slope in the Zhexi Hydropower Station Extension Project is complex and the project is difficult to construct. A three\|dimensional FEM model, which includes three sets of crevices, two sets of the staggered rock layers and rock anchors, is established. The construction sequences are simulated in accordance to the actual construction procedure. The results show that the high inlet slope, diversion tunnel and strobe cavern are stable and the excavate construction procedures are reasonable and feasible. But the two sets of crevices and two sets of the staggered rock layers may affect the stability of the high inlet slope, diversion tunnel and strobe cavern. The supporting solutions for these potential instabilities are proposed in this paper. The monitoring results during the construction was validated the analytical results. Related Articles | Metrics

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Limit Equilibrium Analysis and Construction of Loose Soil Slopes with Buildings Nearby QIAO Zheng1, ZHOU Hui fang2, XU Wen long1, XIE Lin lin3 2011, 25 (6):  8.  Abstract ( 2365 )   Save Cut slopes are planned at both sides of the Qingwang Road widening project. The proposed slopes have loose soils with buildings nearby. The limit equilibrium method was applied to analyze these slopes and the analytical results were used to provide guidelines for the design of supporting structures. Slope stability analyses also provide guidance for the slope cut and supporting structure construction sequences. Related Articles | Metrics

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Application of Pre\|stressed Ground Anchors in High Cut Slopes in Red Clay Soils ZHANG Qing1, MOU Chun mei1, LI Wang xing2 2011, 25 (6):  11.  Abstract ( 2485 )   Save The procedures and technical details of pre\|stressed ground anchor installations are presented throughout a case history in a red clay soil cut slope construction located in a section of the Shuige, Guizhou Prov. of the Xiamen\|Chengdu Expressway Project. The pre\|stressed ground anchors along with the reinforced concrete anchor frames were tested and monitored in the project. A cost saving was achieved compared with other slope stability methods.    Related Articles | Metrics

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Failure Modes and Stability Evaluations of a Mine Slope YAN Ke cheng, HUANG Jing, WANG An bin 2011, 25 (6):  14.  Abstract ( 2627 )   Save Mine slope stability evaluation is one of the most current topics in geotechnical engineering. A mine slope in Tianyang County, Guangxi Province was selected as a case study in this paper. Based on the analysis of the failure mode of the slope, slope stability was evaluated using limit equilibrium, numerical modeling and stereographic projection approaches. Three methods from different prospective were used to evaluate the same problem to ensure reliability of the mine stability prediction. This case study can also provide an example for stability evaluations of similar mine slopes in Southwest China. Related Articles | Metrics

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Back--Analysis of Strength Parameters of Stepped Cut Slopes in Shuisui Highway PENG Jin yu1， LIU Yong li2, PENG Xiao mao1， WU Jian liang1， 2011, 25 (6):  17.  Abstract ( 3221 )   Save Stepped cut slopes in loose rock masses were constructed adjacent to the Shuisui Highway, Yunnan Province. Based on the typical slope cross sections and typical subsurface geotechnical conditions, both the local and overall critical slip surfaces are computed by using the limit equilibrium search method. The results indicate that the factors of safety under both natural and fully softened conditions are less than 1.0. The constructed stepped cut slopes appear to be unstable. However, it is observed that current slopes are stable and no historical records of any slope failures are evident, even under rainfall conditions.  These cut slopes were back\|analyzed to re\|evaluate the strength parameters of the loose rock masses based on the observed stable conditions. The back\|analyses provide more reasonable strength parameters for the geo\|materials and also improve the reliability of the evaluations of cut slope stabilities. Related Articles | Metrics

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Analysis of the Stability and Factors Affecting the Gaozhuangchang Landslide CHEN Ji hua1, ZHOU Hai hui1, WANG Qiu jun1, ZHANG Hai liang2 2011, 25 (6):  20.  Abstract ( 2653 )   Save The Gaozhuangchang town is located in Pingwu County, Sichuan Province. Although the landslide near the town was caused by the Wenchuan Earthquake, noticeable deformations were observed recently. The deformations at the landslide site pose the serious property and traffic safety concerns of the local residents. In this paper, the characteristics and classification of this landslide were studied. The slope stability analyses and assessment were performed using force in\|equilibrium method. Base on the analytical results, factors that affecting the landslide were evaluated.  Related Articles | Metrics

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Studies on Lining Parameters of a Large Cross Section Tunnel in the City  LOU Xiao ming1， GONG Yan feng2 2011, 25 (6):  23.  Abstract ( 2691 )   Save The Jinshazhou Tunnel of Wuhan\|Guangzhou High\|speed Rail Project is northwest of Guangzhou City. In order to assure the safety and the cost effectiveness of this tunnel during construction and operation, the lining parameters for the primary and quadric lining supports are studied. Based on the design codes and the site geotechnical conditions, the primary and quadric lining support parameters are obtained for the Class IV surrounding rock masses by using the Analogy Method. Then, the finite element analyses are performed on the same Class IV surrounding rock masses by considering the effect of groundwater. Therefore, the stress changes on the primary and quadric supporting structures can be predicted. These approaches provide a viable solution for the design and construction of this large cross\|section tunnel in an urban area. Related Articles | Metrics

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Supporting Structures for a Large Deep Excavation in Soft Soils MA Yun1，2， XU Guang li1 2011, 25 (6):  26.  Abstract ( 3682 )   Save The normal water table level in the Yangtze River near Jingzhou City is above the ground surface inside the Jingjiang Embankment. A deep excavation site in the center of Jingzhou City is only 700 m from the embankment along the Yangtze River. Due to its proposed eight meters of excavation depth, this site is classified as Level I on the Importance Class Scale (most important). This site is characterized by underlying saturated soft soil strata, high artesian water head and adjacent structures that are sensitive to construction disturbance. Therefore, stringent requirements are placed on deep excavation design and construction. Using theoretical analysis and empirical judgments, different supporting structures are selected based on the characteristics of soil strata and the geometry of the excavations at the various locations. Supporting structures include cast\|in\|place piles, rigid frame piles and arch\|supporting piles. These supporting structures are not only for the excavation construction easement but also for minimizing settlement and differential settlement problems surrounding the structures. Related Articles | Metrics

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Optimizing of Supporting Structures for a Subway Station Deep Excavation WANG Chang, XIAO Zhao ran, JIANG Min min 2011, 25 (6):  31.  Abstract ( 3123 )   Save For installation of prop structures, the effect of variables such as horizontal spacing, location as well as the pre\|stresses within the propos, on the performance of deep excavations is investigated through numerical analyses with site specific subsurface conditions. Based on the analytical results, the design of supporting structures for the deep excavation construction of a subway station in Zhengzhou City can be optimized. The improved design had a better performance in deformation control during the excavation and resulted in a significant cost savings.   Related Articles | Metrics

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The Evaluations of the Highway Embankment Settlements WANG Bing1, ZENG Chao2 2011, 25 (6):  35.  Abstract ( 2723 )   Save In this paper, the case study of the highway embankment settlement monitoring and evaluation are presented. The distribution of the settlement monitoring points is first introduced. The observed settlement data are analyzed and evaluated. These data are used for the benefit of the construction.   Related Articles | Metrics

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Seismic Response Analyses at a Power Plant Site YU Zi hua, LIAO Ai ping, YU Feng, MENG Xi chun 2011, 25 (6):  37.  Abstract ( 2093 )   Save In this study, the time histories of the synthetic bedrock ground motions have been generated to simulate various earthquake moment magnitudes at probabilities of 10%, 2%, and 1% in fifty years level with an epicentral distances of 40 km. Applying these bedrock time histories into the soil profiles of a power plant site in northern Hunam Province. By using surface seismic shear wave method, which is a one\|dimensional, equivalent\|linear analysis, the ground response under the seismic ground motion was obtained. The computed acceleration time histories, response spectrum and amplification spectrum are most useful parameters for seismic design. Related Articles | Metrics

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The Ground Subsidence Investigations and Analyses LI Dong dong, FENG Xiao zhou 2011, 25 (6):  40.  Abstract ( 2824 )   Save The ground subsidence phenomena at a site are investigated in this paper. Geological conditions are analyzed through regional geology maps, hydro\|geological profiles and historical boring information in the region. The distribution of the subsided area, settlement contours, quantities of groundwater extractions for industrial and residential needs, groundwater level underneath the subsided area and deformation of the building structures were monitored over an extended period of time. The monitoring data suggest that the ground subsidence was induced by excessive extraction of groundwater for fishing ponds. The consolidation of saturated soils resulted in differential settlement of the ground. Related Articles | Metrics

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Uplifting Check and Groundwater Drawdown Design of Deep Excavations Considering Seepage WU Tie hua 2011, 25 (6):  44.  Abstract ( 3123 )   Save The seepage balance method, which is used in checking the uplift force in deep excavations, is studied based on the mechanism of seepage deformations. In this paper, this method is also compared with the classical force balance method in terms of theoretical derivation, variables and range of applicability. It is concluded that the classical force balance method often leads to a conservative solution whereas the seepage balance method results in an economical solution. It is also noted that, in the Roller Compacted Earth Dam Design Specifications (SL274-2001), the factor of safety from the resultant seepage balance method should be greater than 1.1 and should be less than the 1.5, which is the lower bound suggested in the new specifications. The suggested factor of safety values are obtained similar to the derivation of safety factors using the Simplified Bishop Method and the Swedish Method in slope stability analyses. This paper also compares the results from the seepage balance method and from other methods when estimating the groundwater drawdown in deep excavations. It is suggested that the seepage balance method results in a smaller groundwater drawdown. Related Articles | Metrics

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State-of-the-Art of Shield Tunnel Model Tests SUN Ji zhu， XIAO Wen hui 2011, 25 (6):  49.  Abstract ( 2461 )   Save Three aspects of state\|of\|the\|art research on shield tunnel model tests are reviewed in this paper. These aspects are: displacement and stress changes in the underground strata; stability of excavated faces and pressures on the supporting structures, and stratum adaptability of tunnel excavations. Limitations existing in the shield tunnel conventional and centrifuge model tests are also discussed. Based on the success of the synthesis of a transparent soil, a new model test system is presented. This new system consists of a plexiglass shield model, an optical measurement device and a Particle Image Velocimetry (PIV) digital image processing system. The improved system can be used to study ground movements and the stability of the excavated faces due to the shield tunneling.   Related Articles | Metrics

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DEM Investigations of the Influence of Particle Crushing on the Shear Properties of Sands LI Yong song1,2, ZHOU Guo qing1, CHEN Guo zhou1,2, ZHOU Jie3 2011, 25 (6):  53.  Abstract ( 2303 )   Save A numerical investigation model using the Discrete Element Method (DEM) was established by the particle flow code in two dimensions (PFC2D) to simulate the biaxial shear tests on non\|crushable circular and non\|circular particles and crushable non\|circular particles. Physical biaxial shear tests were also performed on the sand samples. The objective of biaxial shear tests with both numerical and physical models is to evaluate the effect of particle crushing on the geotechnical properties of granular soils. It is concluded that particle crushing positively affects the peak strength and volumetric strain of sand. The effect of particle shape on shear strength is more significant at higher confining pressures than at lower confining pressures. The rate of particle crushing is strongly affected by the magnitude of the confining pressures. Based on the recorded location of the particle breakage and on the distribution of the displacement field in the numerical simulations, the microscopic regularity of evolution of the particle crushing and the location of breakage zones were identified. Related Articles | Metrics

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Equivalent Nonlinear Visco\|elastic Model of Soils based on MSC.Marc Redevelopment GUAN Tian ding, CUI Jie, LI Ya dong 2011, 25 (6):  57.  Abstract ( 3631 )   Save An equivalent nonlinear visco\|elastic constitutive model of soils is developed by the use of secondary development programming interface function, USER SUB.HYPELA, on the MSC.Marc software platform. A typical soft soil site in Guangzhou is selected for the study. The site specific seismic spectrum is analyzed by a two\|dimensional finite element analysis (FEA). To verify the accuracy and reliability of the suggested constitutive model, the result compares well with the results from SHAKE 91, the widely accepted software for the seismic reaction of overlying soils. Related Articles | Metrics

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Model Studies of the Passive Earth Pressures Developed at Earth Berms Against Rigid Retaining Walls SI MA Jun1,2, L Guo1 , HU Jian wei1 2011, 25 (6):  60.  Abstract ( 2756 )   Save Passive earth pressures in earth berms against rigid retaining walls in dry sands are modeled in this paper. The passive earth pressures are developed by rotating the retaining wall about a point below the wall base. The earth pressure distributions and the effect of the earth berm width on the magnitude of the earth pressures are studied. The measured earth pressures are compared with the predicted values based on the Multiple Coulomb Wedge Method proposed by Daly M. P. and Powrie W. (2001). It is suggested that the measured passive earth pressures are close to the predicted values and the points of resultant forces are higher than those of the predicted values. Therefore, the Multiple Coulomb Wedge Method can be safely used to predict passive earth pressures on sandy soils in practical applications. Related Articles | Metrics

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The Application of TSP in Tunnel Construction in Karst Region WU Ke1, MA Ming yue2 2011, 25 (6):  64.  Abstract ( 2313 )   Save The mechanisms of Tunnel Seismic Prediction (TSP) are briefly introduced in this paper. TSP applications in the Zijingshan Tunnel in the Daguangnan Expressway Project, where the karst features are highly developed, are presented in detail as a case history. The predicted results were later validated by the construction. Related Articles | Metrics

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Experimental Studies on the Permeability of Soil\|Aggregate Mixtures ZHOU Jun heng, LI Yan xiang, JIANG Gang 2011, 25 (6):  67.  Abstract ( 2895 )   Save Soil\|aggregate mixtures are composed of gravel, sand, and clay soils. Their permeability is highly inhomogeneous due to the complexities and variations of their macro and micro structures. In this paper, constant\|head permeability tests were performed by large diameter permeameters on soil\|aggregate mixture samples with five (5) different gradations. The factors that potentially affect the permeability of the soil\|aggregate mixtures are also discussed in this paper. These factors include: coarse as well as fine aggregate contents, coefficient of uniformity and mean grain size. Piping failure modes in the soil\|aggregate mixtures are also analyzed. Related Articles | Metrics

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Experiments on the Strength of the Cement Treated Shanghai Silty Clay Soils WANG Yu hui1, WU Ke bing2, ZHA Long long1 2011, 25 (6):  71.  Abstract ( 2639 )   Save To study the strength properties of the cement treated Shanghai Fengxian silty clay, several groups of unconfined compressive strength tests are conducted. Based on these test data, the relationships are obtained between the unconfined compressive strength and the curing age and between the unconfined compressive strength and the cement content with various curing ages. Related Articles | Metrics

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Further Discussion on the Compatibility of Foundation of Stress Coefficients GUO Jian yang 2011, 25 (6):  74.  Abstract ( 1981 )   Save This paper points out the “incompatibility” problem that exists in the additional effective stress table. Issues such as two sets of combinations of stress coefficients and the unification of the stress coefficient formulas are also discussed in the paper. Related Articles | Metrics