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20 February 2012, Volume 26 Issue 1 Previous Issue    Next Issue

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Application of the Large Diameter Single Layer Circular Bracing Structure in a Deep Excavation XU Kaijun 2012, 26 (1):  1-4.  Abstract ( 2149 )   Save The circular bracing structure is getting popular as a supporting system for the deep excavations. This paper presents a case history of applying the large diameter (109 meters in diameter) single layer circular bracing structure in a deep excavation in Puning City, Guangdong Province. The design and construction aspects of the circular bracing system are summarized here in the paper. Related Articles | Metrics

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Application of Replacing Muck by Controlled Blasting in the Revetment Construction FU Min 2012, 26 (1):  5-8.  Abstract ( 2516 )   Save This paper presents a design and construction case history of replacing soft muck soils with controlled blasting method during the construction of Eastern Revetment of Ningde Nuclear Power Plant. The project practice indicates that this method is reliable and can meet the requirement of both construction schedule and the cost control without compromising the engineering quality requirements. Related Articles | Metrics

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Applications of Ring Beam Supporting System in Deep Excavations CHENG Jianguo1, MO Yun2, XIE Wujun2 2012, 26 (1):  9-11.  Abstract ( 3574 )   Save The ring beam supporting structure is a special form of internal supporting system. Based on a case history, characteristics of the ring beam supporting structure are analyzed, and the structure design and construction aspects of the system are also introduced in the paper. The critical issues that might affect the design and construction and their solutions are pointed out. Related Articles | Metrics

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DPT Evaluation of the Effects Sand Gravel Columns and Dynamic Compaction Treated Soils QIAN Xiaobin1, ZHANG Zhenyong1, LIU Guanshi2 2012, 26 (1):  12-15.  Abstract ( 3152 )   Save The proposed Wangjiadun Duishan Park is on the soft soils. The combination of sandgravel columns and dynamic compaction methods are found to be most economical. To verify the feasibility of this soil improvement concept, the pilot study was conducted at two locations. The effect of the improvement was evaluated by the Dynamic Penetration Test (DPT) method. The DPT testing was performed at soils between sandgravel columns. From the DPT blow count changes before and after the improvement, it is concluded that the shear strength of the composite soil mass was improved after the installation of the sandgravel columns. After the dynamic compaction, the shear strength of the deep deposited soils increased but the soil strength at shallow depth decreased. Related Articles | Metrics

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Design and Construction of Completely Dynamic Replacement for Saturated Soft Clays KONG Lingzhi1，YE Zhiyong2，JIANG Jianbing3，LI Jihua4 2012, 26 (1):  16-18.  Abstract ( 2284 )   Save A completely dynamic replacement is one method of various dynamic compaction methods for ground treatment. The objectives of the completely dynamic replacement method are to improve the bearing capacity of subsurface soils and to reduce potential ground deformation under the structural load. The design and construction considerations when utilizing this method to improve saturated soft clays are illustrated throughout a case study. Related Articles | Metrics

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The Application of a New Rotary Drilling Method in a Piling Construction LIU Zhaocheng, LI Qibiao, YANG Ying, XUE Baohua 2012, 26 (1):  19-20.  Abstract ( 2075 )   Save Based on a case study, this paper discusses the common problems that are encountered in the castinsitu pile installations by using a new static slurry drilling method in soft soils in the HarbinDalian Passenger Rail project. The solutions to the problem encountered and the recommended construction procedures are also presented in this paper. Related Articles | Metrics

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Liquefaction Characteristics and Mechanism of Coral Reef Sediments MENG Qingshan, QIN Yue, WANG Ren 2012, 26 (1):  21-24.  Abstract ( 2395 )   Save To investigate the porous and particle crushing characteristics of the coral reef debris (calcareous sand) from a small lagoon in Yongshu Reef of Nansha Islands, the insitu dilatometer tests as well as the laboratory static & cyclic triaxial and torsional shear tests are conducted. The liquefaction characteristics of the calcareous sand are analyzed. The test results show that the calcareous sand at the shallow waters would liquefaction under seismic loading with a magnitude of seven. Under the wave actions, the interand intragranular voids would experience a constant restructuring process and may results in the particle crushing. The peak pore pressure of saturated calcareous sand increases with the number of vibration cycles. The development of the pore pressure in the particles can be divided into four stages: parabolic growth, linear growth, exponential growth and stable state. Liquefaction of the saturated calcareous sand is likely to be streaming slide damage under the isotropic consolidation conditions. Related Articles | Metrics

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Stress and Strain Characteristics of Ground Anchors on Cut Slopes YU Zihua, MO Zhibai, LIAO Aiping, ZHOU Zheng 2012, 26 (1):  25-29.  Abstract ( 2533 )   Save The case history of a cut slope in presented in this paper. The geologic and geotechnical parameters were obtained through test borings and insitu tests. The pullout tests on the ground anchors were performed and the stressstrain characteristics of the ground anchors were backanalyzed by the numerical analysis. The backanalysis results indicated that the maximum shear stress at the interface between the rock and the cement grout is at the top of the bond zone. It gradually reduced to zero at a distance of 1.5 m to the top of bond zone. The shape of the stress distribution is similar to a narrow parabola. A lower stress magnitude was found in the numerical analysis compared with the stress obtained from elastic closedform solution. Related Articles | Metrics

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Blasting Vibration Control of Foundation Pit Excavation in Nuclear Unit at a Nuclear Power Plant HUANG Fuqiang1，ZHANG Dayan2，XIA Xiang3 2012, 26 (1):  30-32.  Abstract ( 2384 )   Save In foundation excavation of a nuclear power plant, the blasting vibration should be controlled strictly in order to ensure the safety of bedrock and nearby buildings and structures. The authors presented the whole process of vibration monitoring and vibration reduction method based on the foundation excavation of the nuclear island. The in situ blasting tests reveal that shock absorption holes can reduce the blasting vibration. The vibration velocities of rock particles increase with hole spacing, and decrease with hole diameter. It is more efficient in practice to reduce blasting vibration by reducing shock absorption hole spacing than by extending hole diameter. Related Articles | Metrics

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Numerical Analysis of Deep Excavation in Soft Clay Using Unified Hardening Model ZHEN Wenzhan 2012, 26 (1):  33-36.  Abstract ( 2753 )   Save The Unified Hardening (UH) model can characterize many aspects of clay stressstrain behaviors, such as, straining hardening and softening, stress dilatancy, as well as the stress path dependent. A users defined material subroutine implementing the UH model was developed using the return mapping algorithm in the commercial finite element analysis software ABAQUS. The UH model was validated by simulating the loadingunloading process in the triaxial compression and other stress paths on a testing element. The results indicated that this constitutive model can reasonably characterize the soil behavior under different stress paths and overconsolidation ratio. This UH model was then applied to simulate a deep excavation of a subway station in cohesive soils. The numerical simulated deformation of the excavated area and the stress in the supporting structures were compared with the measured values. A satisfactory agreement was found between the measured and predicted values. Related Articles | Metrics

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DEM Research on Thickness and Influence Factor of Interface Layer LI Yongsong, ZHOU Guoqing 2012, 26 (1):  37-40.  Abstract ( 2689 )   Save A series of numerical soilstructure shear tests were performed by Particle Flow Code (PFC) in two dimensions, the effect of the roughness of the interface and the particle radius on the thickness of the interface layer were studied. It is shown that the roughness of interface and the particle radius affect the thickness of interface layer significantly; the thickness of interface layer increases with the decrease of the particle radius as well as the increase of the roughness of the interface. Related Articles | Metrics

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Construction Hazard Alarming and Stability Analysis of Tunnels in Groundwater Rich Fractured Zone ZHANG Lifeng1, SUI Bin2 2012, 26 (1):  41-44.  Abstract ( 2435 )   Save In this case history of highway tunnel in the mountain area, the geological hazard alarming and control of tunnels in groundwater rich fractured zone are studied by using geological prediction (induced polarization) and numerical analysis methods. The results indicate that the induced polarization method can reliably locate the groundwater rich fractured zone and its horizontal and vertical limits. The predicting of the fractured zone can provide a better control of tunneling activities through the adverse geological condition. The distributions of seepage, stress and strain around the fractured zone after the tunnel excavation can be predicted by the numerical analysis. Therefore, appropriate tunnel excavation and supporting schemes can be selected based on the predicting and analysis results. Related Articles | Metrics

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Lining Thickness on the Supporting Stability of Multi arch Tunnels WANG Fei, LI Haoyu, SHEN Hongbo 2012, 26 (1):  45-48.  Abstract ( 2557 )   Save The stress distributions in the multiarch tunnels with various lining thickness were analyzed through the finite element method. The factor of safety of the lining structure correspondent to the lining thickness is obtained from the analyses so that the appropriate lining thickness can be selected. These results can be used in the design the similar lining structures for the multiarch tunnels. Related Articles | Metrics

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Testing of High Fill Grounds Treated by the Dynamic Compaction ZHAO Qi yuan, WU Wen xiang, ZHOU Wen you 2012, 26 (1):  49-50.  Abstract ( 2299 )   Save Static plate load tests were performed on the high fills treated by the dynamic compaction method. The detailed results of dynamic compaction on high fill have also been described in this paper. Related Articles | Metrics

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Studies on the Relationship Between the Results of the Flat Dilatometer and Total Pressure Cell Tests PENG Junwei 2012, 26 (1):  51-55.  Abstract ( 2455 )   Save The relationship between the results of horizontal stresses measured from The Flat Dilatometer Test (DMT) and The Total Pressure Cell Test (TPCT) in the saturated clay was developed based on the Mindlin's elastic solution. It is concluded that the initial total stress σ  h0is greater than the contact pressure p0 on the DMT membrane before the inflation. This result was verified by the test results using DMT and TPCT in a railway project in Huzhou area. Related Articles | Metrics

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Laboratory Studies on the Strength Characteristics of the Crust above Soft Soils FAN Youjie 2012, 26 (1):  56-59.  Abstract ( 2800 )   Save Extensive conventional laboratory soil index tests and consolidatedundrained (CU) triaxial shear tests on undisturbed soil samples were conducted from various projects. These undisturbed soil samples were collected from the overconsolidated crust layer as well as from the underlying soft soil stratum. Both physical and mechanical properties of the crust layer and the soft stratum are compared in this paper. The comparisons lead to taking the advantage of the upper overconsolidated crust layer in practical engineering projects. Related Articles | Metrics

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Detecting of Adverse Geological Conditions in Long Tunnels by Seismic Waves HONG Weiliang 2012, 26 (1):  60-62.  Abstract ( 2737 )   Save The seismic wave TSP (Tunnel Seismic Prediction) method is widely used in the geological condition prediction in recent years.  In this paper, the TSP Model 203 was used to detect the adverse geological conditions of a long tunnel. Based on the data collected, the locations and limits of the fractured zone and the groundwater rich area can be reasonably determined. The further explorative drilling guided by the seismic wave predictions can verify these adverse geological conditions. The detection and drilling results provided technical bases for the advanced grouting in the fractured zones. The monitoring results during and after the construction indicate that this method is satisfactory. Related Articles | Metrics

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Application of the Screw Anchor in Static Loading Tests ZHAN Jinlin 2012, 26 (1):  63-66.  Abstract ( 2113 )   Save This paper briefly introduces the screw anchor technology, its application and its advantages. The pullout capacities of both shallow and deep anchors are also provided in this paper. These formulas were applied in designing the reaction for a static plate load testing program at a collapsible loess site treated by the dynamic compaction. The soil parameters used in the pullout predictions were obtained from the test boring information and laboratory test results. The predicted values for both single and double anchors were verified with the onsite pullout test results. So far, the screw anchors has successfully provided reactions for more than 800 static plate loading tests. Related Articles | Metrics

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The FreezeThaw Cycling Testing on Lime Treated Expansive Soils LI Ziling1, JIN Yanwen2 2012, 26 (1):  67-69.  Abstract ( 2540 )   Save A series of consolidated undrained triaxial shear tests were performed on lime treated expansive soil samples experienced freezethaw cycles. The impact of freezethaw cycling on the shear strength parameters of treated soils has been studied. The relationship between the shear strength of the treated soils and the number of freeze thaw cycles is developed through the study. The failure mechanism of the lime treated expansive soil due to the freezethaw cycling is also presented in this paper. Related Articles | Metrics

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Field Studies on the Bearing Mechanism of Belled Columns Formed by Jet Grout LI Bing1，GUO Kecheng1，JIANG Chong2, Hu Yifu2 2012, 26 (1):  70-73.  Abstract ( 2469 )   Save This case study presents the results of column supported foundation by both the conventional jet grout and the jet grout expanded bases in a soil improvement project for a food storage garages and yards. The ground surface settlements, soil mass deformations, lateral deflections of soil around the columns, excessive pore pressures and the stress ratioes were monitored by the geotechnical instrumentations. The site was also tested by the field vane shear, cone penetration and static plate loading tests before and after the soil improvement. The results indicate that the belled column has a better performance compared with the conventional jot grout columns. Related Articles | Metrics

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Application of GPR on the Advanced Prediction in A Highway Tunnel Construction WU Xiaomeng，YUE Xianghong，YANG Yongbo 2012, 26 (1):  74-76.  Abstract ( 2235 )   Save Due to the complexity and uncertainty of the geological conditions, geological hazards often occur during the construction of tunnels. This paper presents a case history of applying Ground Penetrating Radar (GPR) in the construction of Cikou Tunnel of Songjian Expressway. The scanned images obtained by GPR were verified with the existing geological information and the tunnel excavation. The results indicate that the GPR prediction is a good measure of detecting fractured and/or groundwater rich zones in the tunnel construction. Related Articles | Metrics

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Experimental Study on Recycled Concrete as a Roadbed Filling Material FU Liang1，GUO Jinjing2，MENG Qingxin1 2012, 26 (1):  77-79.  Abstract ( 2109 )   Save This paper presents a method of recycling the waste concrete. Based on the soilcement curing mechanism, the recycled concrete hardening mechanism is discussed. The unconfined compressed tests were performed on the soilrecycled concrete samples with different particle sizes. Related Articles | Metrics

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Researches and Applications of Fiber Reinforced Soils BAO Chenggang，DING Jinhua 2012, 26 (1):  80-83.  Abstract ( 2444 )   Save This paper briefly introduces the basics of fiber reinforced soils, working mechanism and the mechanical characterization of reinforced soil mass. The properties of the fiber reinforced expansive soils, the failure modes and the factors affecting the reinforcement are also presented in the paper throughout the state of the art research results. The application of the fiber reinforced embankment soil is introduced through a case history. Related Articles | Metrics