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28 February 2013, Volume 27 Issue 1 Previous Issue    Next Issue

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Procedures of Soil Improvement using Sand Columns for the High Speed Rail Embankments LUO Cunxi 2013, 27 (1):  1-4.  Abstract ( 2397 )   Save The sand column construction procedures and results are compared at a test embankment site in order to study the feasibility of applying sand column method in the high speed rail embankment construction. Two types of sand column installation methods are used: Vibration Method and Percussion Method. Both types of equipment have the similar penetration depth and column installation quality, however, the equipment with vibration method has obvious advantages over the percussion equipment. In addition, the percussion installation method generates excessive noise and therefore has the limited applications under the urban and night installation environment. Base on the test embankment results, it is recommended that the vibration installation method is used in the construction. Related Articles | Metrics

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Design and Evaluation of Breasting Dolphin System of a Floating Dock in Changsha City WANG Li 2013, 27 (1):  5-7.  Abstract ( 2203 )   Save The paper introduces the components and operational principles of the breasting dolphin system for a floating dock in Changsha City. The innovative design aspects of the breasting dolphin system, especially, the steel pile jacking process , are also introduced in this paper. Related Articles | Metrics

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Impact of the Deep Excavation Dewatering on the Settlement of a Subway Tunnel LIU Yunsheng 2013, 27 (1):  8-10.  Abstract ( 2573 )   Save Additional settlement will occur at the adjacent area due to the consolidation effect of the soil mass when a deep excavation site is dewatering. This paper presents a case history of a deep excavation in Tianjin West Subway Station Transportation Hub project. The measures of minimizing the dewatering at the deep excavation on the additional settlement on the existing subway and adjacent structures are discussed. The most economical and safe procedures were developed and optimized. Related Articles | Metrics

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Roots' Former Residence's Preservation in the Yangtze River Tunneling Project HU Bin, YANG Shengshuang, ZHONG Youxin 2013, 27 (1):  11-13.  Abstract ( 2264 )   Save The original design of the shielded tunnel of Yangtze River Crossing project will be in a close proximity below a protected culture heritage building, the Roots' former Residence. Further, the receiving pit of the shielded tunneling is very close to this building. A comprehensive precaution measures are adapted in the tunnel construction in order to preserve this building: The original tunnel receiving pit location was moved away; the super structure and the foundation of this building were strengthened; and the shallow buried shielded tunneling undercrossing technique was also applied. The construction results indicate that these controlling measures are successful. Related Articles | Metrics

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Prediction of the Settlement of High Embankments by Back Propagation Neural Network MA Lihui，HAN Wenxi, LI Yang 2013, 27 (1):  14-16.  Abstract ( 1933 )   Save The post construction settlement of high embankments of T1 to T5 alignments in Kunming new airport project site is predicted using a multilayer (two hide layers) neural network method. The observed settlement values indicate that the maximum post construction settlements are related to areas with highest fills. The settlement pattern indicates that the post construction settlements have a rapid settlement rate initially and then gradually change to the steady settlement. It is predicted that the maximum post construction settlement at T1 is 52.7 mm and the observed value in August 2011 was 55.6 mm. It is concluded that the two hide layer Back Propagation (BP) neural network model can have an accurate prediction on the post construction settlement. Related Articles | Metrics

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Stability Evaluation of the Nested Deep Excavations for Wuhan Centre Foundation SUN Xiaoying1, FENG Xiaola2, XU Sheng2 2013, 27 (1):  17-20.  Abstract ( 2236 )   Save This paper presents a case history of the deep excavations for WuhanCenter foundation construction. The strength and stability aspects of the silty fine sand within the soldier piles in the excavated area within the nested deep excavations under the dewatering conditions are evaluated. The impact of the soil moisture content and clayey lenses on the properties of the insitu silty fine sand is examined. The conclusions of the similar excavation under the dewatering conditions are reached. Related Articles | Metrics

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Gongbei Tunnel Design of HongKong Zhuhai Macau Bridge Connector Project HE Xiaolong, CHENG Yong, GUO Xiaohong， TUO Yongfei 2013, 27 (1):  21-24.  Abstract ( 3212 )   Save The Gongbei Tunnel has a total length of 2,741 meters and is part of the HongKongZhuhaiMacau Bridge Connector Project. The tunnel has a total of six traffic lanes in both directions. The tunnel has the characteristics of large crosssections, shallow embedment, soft soil environment, rich groundwater and the sensitive environment. The construction of this tunnel is the known most complicated geological environment, most difficult in construction and highest technological requirement among all tunnels that under construction in China. Its construction utilizes both cut & cover and partial tunneling methods. The tunneling construction utilizes constructing island first, then cut and cover as well as long distance tunneling, multiple points and curvature jacking methods. Related Articles | Metrics

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The Discussions on the Optimization Design of Foundation Excavations SUN Yafei 2013, 27 (1):  25-27.  Abstract ( 2462 )   Save In order to achieve the goal of a safe, economical and simplicity during the construction in the deep excavation design, this paper discusses several improper designs of the supporting structure connection details. The optimized connections are proposed based on the structural analysis. The improved connection not only reduces the complexity as well as the potential risks in the construction but also result in a cost saving in the materials. Related Articles | Metrics

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Numerical Simulation on the Displacement and the Stress Characteristics of the Prefabricated and Assembled Arch Culverts ZHOU Daqing1，KOU Honggang2， WANG Haibo2 2013, 27 (1):  28-31.  Abstract ( 2265 )   Save Numerical simulations are performed to investigate the displacement of the lateral walls, the stresses of the arching crown and the block pulp layer by means of simplified load method. The soilstructure interaction aspects of this prefabricated and assembled arch culvert are also investigated. The impact of the elastic modulus of the embankment soils on the displacement and stress characteristics of the arch culvert are also simulated. The results indicate that: the displacement and the stresses obtained by the simplified load method and the method considering the soilstructure interaction by finite element analysis do not have a significant difference. The results also show that the displacements and the stresses of all culvert elements are within the code requirements for the structural safety. From the soilstructure interaction analyses, the results of displacement and stress are not sensitive to the elastic modulus of the embankment soils. They are more sensitive to the Poisson's ratio. Related Articles | Metrics

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Effects of Load Reductions for a Precast Slab Culvert under the High Embankment REN Dacheng1， WANG Haibo2 2013, 27 (1):  32-34.  Abstract ( 2469 )   Save The initial stress field of a precast slab culvert under the high embankment is simulated with a two dimensional finite difference model using FLAC3D software. The installation of the culvert as well as the embankment construction is also numerically simulated. Then, the load reduction efforts are simulated by placing the flexible fills on the top of culvert and improving the soil underneath the culvert. The results from the load reduction effort are compared with the initial stress field conditions. It is concluded that, with the increase of the thickness of flexible filling, the maximum stress coefficient, vertical soil pressures on the top as well as at the bottom of the culvert are nonlinearly reduced. No significant vertical load reduction effect is found from the soil improvement. With the increase of soil improvement depth, the vertical soil pressure at the bottom of culvert is decreased. However, the lateral earth pressures acting on the foundation soils are significantly increased. Related Articles | Metrics

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Treatment and Evaluation of Concrete Joints Due to Pouring Interruption ZHENG Qiqi, YANG li， WAN Feiming 2013, 27 (1):  35-37.  Abstract ( 3018 )   Save The interruption of concrete supply during the construction is unavoidable when using the super long concrete pumps. The performance of the concrete joints might be greatly affected by the excessive pouring interruptions. Currently, many measures can be used to improve the concrete joints if the pouring delay is deemed as excessive. Applying the adhesive additives and embedding the dower rebar are among the most popular methods. This paper presents a case history of treating the concrete pour joints caused by the excessive delay in the concrete supply. The theoretical formula for the joint treatment is applied and examined by the actual project. Related Articles | Metrics

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Behavior of the Concrete Filled Circular Steel Column Steel Beam with Mild Steel Nodes ZHOU Wei1，LI Chengyu1，ZHANG Li2，LIU Jian1 2013, 27 (1):  38-40.  Abstract ( 2040 )   Save This paper presents a new connection model, Mild Steel Node, for the concrete filled circular steel columnsteel beam system. The node is finite element analyzed by using ANASYS software. The results indicate that the concrete filled circular steel columnsteel beam with mild steel nodes is an ideal seismic energy dissipation connection. The length of the mild steel connections is also optimized based on the numerical analysis results. Related Articles | Metrics

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Discussions on the Pile Axial Capacity Estimation Formulas ZHANG Xiaoyu1， SHANG Jifa2 2013, 27 (1):  41-42.  Abstract ( 4973 )   Save The load transfer mechanism in an axial loaded pile is studied through the static loading tests on instrumented piles. In the allowable axial capacity estimation formula, the allowable capacity is obtained by using the limiting values of shaft and tip resistance divided by an uniform factor of safety of 2. This approach is not consistent with the actual load transfer mechanism. The ideal pile allowable capacity should be obtained by the limiting values divided by different safety factors. However, at current stage, it is appropriate to use one comprehensive safety factor to obtain the allowable pile capacity since the load transfer mechanism between the pile shaft and the tip are not clear. Related Articles | Metrics

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Application of Eco-Clay Wall Method in the Slurry Wall Engineering ZENG Yu1, XIANG Yan1, XU Guangli2, MA Yun2,3， Ryokai Kimitoshi4 2013, 27 (1):  43-45.  Abstract ( 2229 )   Save With the urban development, the deep excavations are increasing in quantity and also the excavation depth is also getting greater. The groundwater control during the excavation becomes critical for the success of the excavation. This paper reviews the stateoftheart slurry wall construction techniques. A new seepage control wall that was developed by a Japanese firm, Raito Kogyo Co. Ltd is introduced. This wall which has a name of EcoClay Wall is environment friendly compared with the conventional slurry wall types. It has the advantage of excellent groundwater control, long service life, easy to construct, as well as no soil spoils during the construction. Related Articles | Metrics

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The Circumferential Bearing Capacity of Supporting Structures foe a Large Circular Deep Excavations GU Shaofeng， LU Wen 2013, 27 (1):  46-48.  Abstract ( 2184 )   Save The large circular underground supporting structure is a good form of structure which combines the system function of deep excavations as wells as takes the advantage of the arch effect. This structure has the advantage of simplicity, wide applications and fast construction. Currently, the major concern in the structural design is focused on the structural stability. The arch effect is neglected in the conventional vertical section analysis. Therefore, the circumferential stress might be underestimated as a result of the conventional analysis. This paper estimates the tangential and radial stress of the circular supporting structures based on the classical solution of a linearly load elastic tube. It is concluded that the circumferential stress of the circular supporting structure is approximately increased with the radius of the structure. The tangential stress of the supporting structure should be examined for a safe design of the deep excavation supporting structure. Related Articles | Metrics

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Discussions on the Pile Cap Design ZHANG Lili 2013, 27 (1):  49-51.  Abstract ( 2099 )   Save The current design specifications on pile foundations (JGJ94-2008) define the bending, shear and punching design procedures for the pile caps. Throughout the derivations of four different loading conditions at the pile cap, this paper concluded that the current code requirement is underestimate the load and therefore is unsafe. The improved formulas for the bending, shear and punching failure modes are proposed. Related Articles | Metrics

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Mesoscale Simulations of Composite Soil Nailed Wall for the Supporting of Deep Excavations WANG Tao， XIONG Chuanxiang 2013, 27 (1):  52-55.  Abstract ( 2064 )   Save Due to the complexity and the importance of the stressstrain mechanism in the composite soil nailed wall supporting system, the interaction between the soil nailing and the soil mass is approached from the mesoscale simulations by using the theory of particle flow and it associated discrete element software, PFC2D. The new approach bypasses the macro continuity hypothesis of the traditional continuum mechanics model. The wall deformations of a deep excavation site supported by the soilcement mixed wall and soil nailing are numerically simulated by the discrete element method. The change of the stressstrain, pore water pressure and the micro cracks in the soil mass during the excavation are also numerically monitored. The analytical results are close to the observed values. Related Articles | Metrics

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The Safety Analysis of the Deep Excavation SupportUsing Retrievable Ground Anchors SUN Junzhen, ZHANG Dianren， LEI Jinshan 2013, 27 (1):  56-58.  Abstract ( 2590 )   Save The transition of the supporting system from anchored walls is an very important topic when the retrievable ground anchors are using in the supporting of deep excavations. This paper presents a case history of a deep excavation in sandy gravel soils. The deep excavation construction sequence and the ground anchor retrieval as well as the substructure construction are simulated with Finite Element Software MIDAS-GTS. The deformation of the walls is monitored and the results indicate a good consistent between the simulated and observed data. Related Articles | Metrics

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Discussion on the Pile Axial Capacity Prediction through Curve Fitting of Measured High Strain Data HE Shanbing 2013, 27 (1):  59-62.  Abstract ( 3716 )   Save This paper presents three case histories of pile axial capacity predictions through the curve fitting on the measured high strain data. The procedure of the regression of the curve fitting is also summarized. Reasons for the large deviation from the observed data, and methods to improve the prediction are recommended in the paper. Related Articles | Metrics

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Study of Ground Subsidence Induced by the Shallow Buried Tunnel on the Inclined Surface Conditions CAI Hui 2013, 27 (1):  63-65.  Abstract ( 2420 )   Save A shallow buried tunnel is situated in a laterally inclined rock mass. The ground subsidence induced by the tunnel construction is evaluated based on different ground inclination angles: no inclination, 1V:20 H; 1:V:10H and 1V:8H. The double tunnel length has a fixed 10 meters in Class V rock masses. The settlement characteristics of different inclination angle have been evaluated in this paper. Related Articles | Metrics

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Application of Cone Penetration Tests in the Investigation of Large Storage Tank Farms in Loess SU Jian, ZHAO Shengjie 2013, 27 (1):  66-68.  Abstract ( 1858 )   Save This paper presents a case history of the application of Cone Penetration Test (CPT) in the geotechnical investigation of a large oil storage tank farm in loess soils. The details of stratigraphy, bearing capacity of soil foundations, and the axial capacity of single piles are also introduced in the paper. Finally, both advantages and the disadvantages of applying the CPT in loess soils are discussed in the paper. Related Articles | Metrics

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Test Analysis on the Bearing Behavior of Halfscrewed Filing Pile in mudstone foundation TAN Fang, WU Shuai 2013, 27 (1):  69-71.  Abstract ( 2153 )   Save As a new type pile, Research on Halfscrewed Filing Pile is far from enough. The vertical load transmission mechanism thoroughly is analyzed about Halfscrewed Filing Pile in mudstone foundation based on the static load experiment results, except ,ultimate bearing capacity formula is deduced and the reliability basis of the halfscrewed pile design is provided. Related Articles | Metrics

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Impact of Groundwater Fluctuations on the Vertical Deformation of the Corse Sand Soils XIE Lei 2013, 27 (1):  72-74.  Abstract ( 2239 )   Save Scope: investigate the impact of the groundwater fluctuation on the settlement of foundation on the coarse sand soils. Approach: Throughout the model study with different groundwater levels, measure the vertical settlement of sand with different foundation contact pressures. Major Conclusion: Small settlement will be induced due to the rising or lowering the groundwater. Related Articles | Metrics

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Case Studies of the Axial Load Tests of RockBearing Bored Piles Using SelfBalancing Method ZHAO Benchu 2013, 27 (1):  75-80.  Abstract ( 2632 )   Save This paper presents case histories of applying the selfbalancing load test method to the rockbearing bored piles. The ultimate axial capacity of the rockbearing bored piles can be estimated from the plate load tests on the bedrock. A total of 14 selfbalancing load test results on the rockbearing bored piles are documented. It is concluded that the estimating of the ultimate axial capacity of the rock bearing bored piles using selfbalancing load test method is reasonable. Related Articles | Metrics