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20 June 2012, Volume 26 Issue 3 Previous Issue    Next Issue

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The Application of a New Methods Improving the Inland Saline Soils CHEN Ling1, CHEN Jiang2, ZHANG Shanggen1, XIA Huiming1 2012, 26 (3):  1-4.  Abstract ( 2345 )   Save This paper introduces a research result of new methods improving the inland saline soils. Based on the special characteristics of the inland saline soils and the comparison of different soil improvement methods, three methods are found to have both the technical and the cost advantages: geotextile wrapped vibro stone columns, cement slurry in the impervious geotextile tube and the stone piers formed by the dynamic compaction. The geotextile wrapped stone columns cement columns have strong resistant to the corrosive soil environment. Whereas, the dynamic compaction formed stone piers have a good result in treating the super soft saline soils. The construction results indicate that these all three methods can be applied with a fairly simply quality control. Related Articles | Metrics

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The Design and analysis of a Shielded Tunnel Crossing the Railway Station ZHANG Junlong 2012, 26 (3):  5-7.  Abstract ( 2759 )   Save This paper presents a case study of the design aspects of a shielded tunnel for the Kunming subway system. The proposed shielded tunnel is crossing the railway train station. The ground settlement induced by this proposed shielded tunnel was simulated by both two and three dimensional numerical approaches. The analytical results are compared with the observed settlement values. This paper also discusses the impact of the shielded tunnel construction on the adjacent structures and measures minimizing the adverse effects. Related Articles | Metrics

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Design and Monitoring of a Vegetated Reinforced Soil Slope above an Anchored Soldier Pile and Lagging Wall ZHAO Xingli 2012, 26 (3):  8-10.  Abstract ( 2477 )   Save This case study demonstrates the design and monitoring of a vegetated steep reinforced soil slope above an anchored soldier pile and lagging wall for the residential development of Twelve Oak Trees in Shenzhen City. The concept of stiff soldier pile combined with the flexible anchor was applied in the soldier pile and lagging wall design to ensure the longterm stability of the cut slope. The technical details of both vegetated reinforced soil slope and the anchored soldier pile and lagging wall are introduced in the paper. The deformations of this combined retaining system during and after the construction were recorded and analyzed. Related Articles | Metrics

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Obstruction Treatment in Slurry Balanced Pipe Jacking XIONG Bo1, GUO DianTa1,2 2012, 26 (3):  11-13.  Abstract ( 2343 )   Save Slurry balanced pipe jacking method is widely used in the urban sewer network construction. Occasionally, if boulders are encountered during the jacking process, the conventional treatment methods will usually have an adverse effect on both schedule and cost. This case history presents a new way to overcome the obstructions in a pipe jacking project in Guangzhou. The new method involves the reversal jacking by using the receiving pit as a temporary launching pit. The reversal jacking is performed with the steel casing protected open excavation. The soil at the front working face is removed by manual hand dig. Jet grout is used in areas adjacent the reversal jacking to seal off the ground water. The case study indicated that this method is successful and cost effective. Related Articles | Metrics

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Prestressed Concrete Pipe Pile Supported Embankment over Thick Soft Soils in Panyu HE Xiaolin, HE Lihong, FAN Wei 2012, 26 (3):  14-16.  Abstract ( 2504 )   Save This paper introduces the application of prestressed concrete pipe pile supported embankment over thick soft muck and mucky soils during the construction of Huanglan (west section) expressway. The pile installation started in February 2010 and completed in August 2010. The embankment construction was completed in January 2011. The settlement monitoring results indicated that the maximum post construction settlement was 220 mm. This settlement value is consistent with the predicted value during the design stage. Related Articles | Metrics

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Ground Collapse Induced by the Breakage of a  Drainage Pipeline and its Remediation CHEN Jianbin, WU Feifei, FAN Wei 2012, 26 (3):  17-20.  Abstract ( 2153 )   Save This case study presents a sudden ground collapse at Baishazhou Boulevard in Wuhan city and its emergency remediation. The conventional approaches of underground drainage pipe construction techniques and their induced engineering hazards are also discussed. It is concluded that the SoilMixingWall (SMW) method has an advantage for the open excavation support in the emergency remediation. The SMW construction parameters in the silty soils fed back from the construction observation are also summarized in the paper. Related Articles | Metrics

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Design of Matoushan Tunnel in the Second Line of West-East Natural Gas Transmission Project XIONG Xiaogang 2012, 26 (3):  21-23.  Abstract ( 2552 )   Save The design aspects of Matoushan tunnel in the second line of WestEast Natural Gas Transmission Project is introduced in this paper. The comprehensive design considered the characteristics of the pipelines and the geological and hydrological conditions of the project site. The paper discusses the design aspects of the cross section dimension and shape of the tunnel, tunnel lining, excavation and drainage measures. The location of the pipeline and its stability has also considered. Construction safety, environmental disturbance and erosion control aspects are discussed in the paper. Related Articles | Metrics

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Monitoring and Analysis of the Slope Instability Mitigated by Bored Piles CAO Hui, WANG Jieguang, ZHANG Peng, XIONG Xi 2012, 26 (3):  24-26.  Abstract ( 2527 )   Save The anti-landslide pile is one of the important and widely used methods in the landslide mitigations. This paper documents the instrumentation results of bored piles used as the slope stability elements in a high slope stability of a power plant construction in Guangxi Province. The horizontal deformation at different depths, rebar stress in piles, and the stress in the prestresses anchors are monitored. The results indicate that the bored pile is effective in mitigating the potential instability. Related Articles | Metrics

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Deep Excavation Support Design and Emergency Remediation YUAN Weiyao 2012, 26 (3):  27-29.  Abstract ( 2204 )   Save The detailed supporting design for different sections of a deep excavation is required if the subsurface conditions are complicated. This case history introduces the design aspects of a deep excavation project with multiple supporting schemes. The emergency supporting remediation measures for the excessive horizontal displacement during the construction are also discussed. Related Articles | Metrics

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Dewatering in the Deep Excavation of a Water  Intake Project in Ma'Aden, Saudi Arabia ZHANG Baohua, ZHANG Hongbo 2012, 26 (3):  30-32.  Abstract ( 2696 )   Save This case history presents the dewatering design and construction aspects for a deep excavation for a water intake project in Ma'Aden, Saudi Arabia. The hydrological parameter selections for the design, construction monitoring and the results are also discussed in this paper. Related Articles | Metrics

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Comments on method of slices of slope stability analysis YANG Xueqiang, LIU Yongjian, WANG Shixu 2012, 26 (3):  33-35.  Abstract ( 2396 )   Save In order to improve the understanding of the method of slices for the slope stability analysis, some important common issues are discussed in detail. These issues are: independent assumption equation numbers, different ways approaching slope stability solutions, importance of moment equilibrium equations, and failure slip surface shape.  The role of Pan's principle for slope stability analysis is also discussed. Related Articles | Metrics

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Analysis on Negative Skin Friction of the Vertically  Loaded Piles under the Surface Load LI Fangzhen, CHEN Zhibo 2012, 26 (3):  36-39.  Abstract ( 2536 )   Save Based on the finite element analysis on the soilpile interaction by using ADINA, the effect of the largearea surcharging on the negative skin friction as well as the neutral point location are evaluated. The position of the neutral point in the pile varies with the consolidation time of surrounding soil and the magnitude of the surcharging. The results also show that negative skin friction on the pile increases with the consolidation time under surcharging load. Related Articles | Metrics

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Analysis of the Impact of a Cut and Cover Tunnel Construction over the Subway LI Hongli 2012, 26 (3):  40-42.  Abstract ( 2661 )   Save Subway network grows rapidly in many large cities. More and more subway lines will unavoidably cross over with the further network expansion. It is critical for the operational safety of the existing subway while constructing the new crossover subway tunnel. This paper presents the numerical analysis results of a cut and cover tunnel in south Nanjing over the existing subway. The bottom heave of the existing subway during the open cut construction is predicted. The construction sequence is optimized based on the numerical analysis results. The upheaval values from the numerical simulations are compared with the observed deformation during the construction and found they were consistent. It is concluded that the numerical analysis can provide valuable guidance during the design stage. Related Articles | Metrics

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Statistical Analysis of the Relationships between Mechanical and  Indices Properties of Xuanmen Bay Soft Clays XU Yanbing1, LI Yonghe2, CHEN Pan3, WANG Jili3 2012, 26 (3):  43-46.  Abstract ( 2933 )   Save The comprehensive statistic studies on the relationships between the mechanical and the various indices properties have been performed on undisturbed soft clay samples from the third phase construction of Xuanmen Bay sea dikes in Zhejiang. The results indicate the some good relationships do exist between the mechanical properties and the physical indices. The both mechanical and physical properties change with the deposition depth and the soil fabrics. The linear regression analysis results show that good correlations between the compression coefficient and the void ratio as well as the natural moisture content, whereas, the soil sensitivity does not have a good relationship with the void ratio. It is concluded that, at the preliminary design stage, it is possible to use the physical indices to estimate the soil compression coefficient. Related Articles | Metrics

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Numerical Analysis on the Highway Slope Stability  Based on Strength Reduction Method KANG Ping1, MU Wei1, WANG Zijie2, ZHANG Deming2 2012, 26 (3):  47-49.  Abstract ( 2350 )   Save Slope stability evaluation has an important role in the geologic hazards prevention and minimization. This paper evaluates a highway slope by using the finite element analysis (FEA) with strength reduction method. The relationship between the stability number and the deformation failure is developed through the analyses. The FEA results are also compared with the results from the limit equilibrium method. It is concluded that the FEA with strength reduction can better represent the stress distributions within the slope. Related Articles | Metrics

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Study of the Appropriate Slope Angle for Lime Improved Soil Embankments ZHOU Dali, YANG Shuhua, YAO Shengpeng 2012, 26 (3):  50-53.  Abstract ( 1863 )   Save The embankment constructed with lime improved soils has a higher strength and better stability. Compared with the embankments constructed with conventional soils, the lime improved embankments can be safely constructed with steep slope and result in a lower construction cost. However, the method to determine the appropriate slope angle for the lime improved embankment has not been reported. This paper first discussed the mechanism of the lime improved embankments and the micro-structures of the lime treated soils. The effect of different slope angles and embankment heights on the slope stability is studied with GeoSlope software. The paper also summarizes the case histories of two lime improved embankments and the appropriate slope angle for the lime improved embankment is recommended. Related Articles | Metrics

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Pre-Limit State Earth Pressure Distribution along Piles Back  Analyzed from the Pile Horizontal Displacements HUANG Zhengsheng, LIU Chengyu 2012, 26 (3):  54-56.  Abstract ( 2165 )   Save The earth pressure is the major loading for the design of the deep excavation supporting system. Therefore, it is essential to accurately estimate the earth pressures along the supporting piles in order to safeguard the excavation construction. This paper presents the prelimit state earth pressure distribution along the pile. The earth pressures were back analyzed from the horizontal displacement supporting piles. The results indicated that the earth pressures acting on the piles are between the atrest and active earth pressure theories. This result is consistent with the prelimit state earth pressure distribution assumptions. The actual earth pressures at greater depths are predicted based on the back analysis results. Related Articles | Metrics

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Accelerated Construction Technologies in Long Large  Sized and Deeply Buried Taining Tunnel WU Cunxing 2012, 26 (3):  57-60.  Abstract ( 2474 )   Save The Taining tunnel is characterized as a super long and has a large crosssection. It is deeply buried with a high ground stress. The construction of this tunnel is a challenge. To seal off large volume of groundwater, a number of techniques are used: real time sealing; preventive curtain grouting; radial grouting; and grouting with gunny bags and strings bags. The adverse geological and groundwater conditions are detected by a comprehensive prediction method in combination of both long and short distances. The rock burst hazards was minimized by following methods: preventive geostress relief; controlled blasting; expansion anchoring; shotcrete with wire mesh; steel rebar reinforced rib; and shotcrete with super finegrained zeolite concrete additives. The ventilation concerns in the long large sized and deeply buried tunnel during the construction and the operation are addressed by the inclined shaft with sectional vertical ventilation technique. The research methodologies, approaches and conclusions of this case study can be used for other tunnel construction under similar conditions. Related Articles | Metrics

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Simplified Method Estimating the Bounded Length for Tensional Anchored Piles YANG Chaofa, LIU Faxiang，ZHANG Chao 2012, 26 (3):  61-63.  Abstract ( 2348 )   Save In the excavation supporting system involving with tensional anchored piles, the pile bounding length determination is still a research topic. There is no general consensus in the engineering practice although several bounding length estimation methods are available. No national or industrial design code adopts the bounding length estimation method. This paper proposes a new simplified method of estimating the bound length of tensional anchored piles. The predicted results have been used in a project. Related Articles | Metrics

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Criteria for the Pumping Termination in Vacuum Preloading XIONG Xi, WANG Jieguang, CAO Hui, ZHANG Peng 2012, 26 (3):  64-65.  Abstract ( 2305 )   Save The soft soil improvement project combined with vacuum preloading and surcharge is summarized in this paper. The conventional pumping termination criterion in the preloading project is the settlement rate equal or less than 5 mm per month. The results in this case study indicate that the criterion is excessively high and is difficult to achieve or at very cost if it can be achieved. This study modifies this criterion by considering the unloading and reloading characteristics of soft soils and the over-consolidation phenomena induced by the removal of the surcharge.  The pumping termination criteria can be obtained by considering the allowable post construction settlement of the roadway, even if the settlement rate prior to the pumping termination is greater than the conventional 5mm per month. Related Articles | Metrics

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Construction Aspects of Tunnel Entrance with Shallow Covered Slopes in Loess LIU Chunlong, ZHU Kuzhu, JIANG Fan 2012, 26 (3):  66-68.  Abstract ( 2218 )   Save This paper documents a case history of the Tong-Luochuan Tunnel construction in the Zhengzhou-Xi'an high speed passenger rail project. The construction aspects of the construction of a large cross section with shallow covered slope in the collapsible loess are introduced. These techniques include: Long pipe roof with guide wall and small diameter guide pipe grouting preshielding; Cross Diaphragm (CRD) method; Observation Method (construction is guided with the observed information). The construction practice indicated that these construction techniques effectively reduced the deformation during the construction and prevented the tunnel collapsing accidents. Related Articles | Metrics

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Settlement Calculations for a Municipal Landfill for the City of Wuhan XU JIAJing 2012, 26 (3):  69-71.  Abstract ( 2226 )   Save The settlement prediction of municipal landfills is a major geotechnical issue associated with the sanitary trash process. It is important to conduct the researches on the deformation characteristics of the municipal landfill site. This paper studies the long term settlements of a landfill in Erfeishan of Wuhan during the daily operation as well as the final landfill covers been placed. The results indicate that settlement rate could be as high as 100%. Related Articles | Metrics

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Perspective of the Utilization of the Underground Spaces in Guangzhou WU Fagen, LI Wuping 2012, 26 (3):  72-75.  Abstract ( 2083 )   Save This paper introduces the state of the art of the utilization of underground spaces of both Guangzhou and other cities. The trend of the urban underground space development of Guangzhou is predicted in this paper. A sustainable development strategy of the underground space development and utilization is also proposed. Related Articles | Metrics

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Settlement Analysis of the Staged Loading on a Soft Soil Improvement for the Stockyard of a Steel Mill ZHENG Jun 2012, 26 (3):  76-78.  Abstract ( 2328 )   Save The soft soil underneath the stockyard of a steel mill is improved by the sand and gravel columns with staged surcharging method. The settlements underneath strips A and B are analyzed by both improved Takagi Shunsuke method and onedimensional Terzaghi consolidation theory. The predicted final settlement values are compared with the monitoring values. Related Articles | Metrics

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Strength Characteristics of Guilin Red Clay under Different Stress Conditions WANG Jing, CHEN Qiuguang, SUN Xiaoli 2012, 26 (3):  79-80.  Abstract ( 2174 )   Save Throughout a series of consolidated undrained triaxial shear tests on the undisturbed samples, the stressstrain relationships of Guilin Red Clay under different stress conditions are studied.  The results show that the shear failure of the Guilin Red Clay is mainly plastic. All samples demonstrate high initial modulus at different confining pressures. The failure surface of samples is not planar but a curved surface. Related Articles | Metrics

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Application of SoilColumn Area Replacement Ratio in the Composite Grounds ZHANG Xiaoli 2012, 26 (3):  81-83.  Abstract ( 12783 )   Save "Soil Improvements Specifications for Building Foundations" recommends formulas for the soilcolumn area replacement ratio, but these formulas are only valid for columns with triangular, square, or rectangular distributions. When the column distribution does belong one of the above distributions, the area replacement ratio cannot be calculated from the code recommended formulas. It is understood that the replacement ratio is ratio of cross section of the column and the area of the tributary. The area replacement ratio can be obtained from the graphical solutions. Related Articles | Metrics

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Approaches of Groundwater Control for Deep Excavations ZHANG Hongbo1, CHEN Sheng2, LU Weidong3 2012, 26 (3):  84-87.  Abstract ( 3375 )   Save This paper introduces several dewatering methods for the deep excavations with different hydrological and construction conditions. Related Articles | Metrics

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Leaching Properties of Cement-based Solidified/stabilized  Zinc Contaminated Kaolin WANG Le1, JIANG Ningjun2, ZHU Jingjing2, DU Yanjun2 2012, 26 (3):  88-90.  Abstract ( 2547 )   Save This paper presents a study of Toxicity Characteristic Leaching Procedure (TCLP) leaching characteristics of cementbased solidified/stabilized zinc contaminated kaolin. Zinc contaminated soils used in the test were artificially prepared with varying initial Zn2 concentration, the cement content and the curing time. Results indicate that the pH of leachate remained stable between 10 and 12 before initial Zn2 concentration reached a threshold. When the initial Zn2 concentration exceeded this threshold, the pH value of leachate declined sharply below 8. There is also a threshold of initial Zn2 concentration for the EC value. When the initial Zn2 concentration exceeded this threshold, EC of leachate rose sharply above 7.8 mS/cm. The pH of leachate changed with initial Zn2 concentration and ranged from 6.7 to 11.6. Within this range, the concentration of Ca2 and Zn2 decreased with the increase in pH of leachate. Ca2 and Zn2 ions were dominant in the leachate. Related Articles | Metrics

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Application of Pumping Test in a Geotechnical Investigation of Hangzhou Subway CHEN Haiyang 2012, 26 (3):  91-94.  Abstract ( 2711 )   Save The coefficient of permeability is one of the most important hydrological parameters for the dewatering design. Due to the complexity and diversity for the site hydrogeology, the result of the coefficient of permeability might be greatly different. Based on the pumping tests in the geotechnical investigation of Hangzhou Subway project, different methods of obtaining the coefficient of permeability have been used in the interpretation of the insitu testing results with data collected by the inhouse made automatic data acquisition system. Related Articles | Metrics

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Modification and verification of triaxial apparatus for creep test CHEN Bijun， ZENG Jing， AI Donghai 2012, 26 (3):  95-97.  Abstract ( 2267 )   Save Creep plays an important role in geotechnical related analysis, such as foundation settlement and slope stability. The creep characteristic has been a focus all over the world. This paper discusses the equipment and testing procedure for the creep test, and proposes an approach to modify the conventional triaxial test apparatus to meet the requirement for creep test.  The modified equipment is capable of performing stress controlled triaxial creep test.  The test results from the modified equipment compares well with results of experimental test. Related Articles | Metrics

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In-Situ Permeability Tests on Slurry Walls Formed by Soil Mixing CAO Yuansheng 2012, 26 (3):  98-100.  Abstract ( 1955 )   Save The slurry walls formed by soilcement mixing or jet grout are widely used in the water resource and hydropower engineering projects where an impervious curtain is required. The insitu permeability test is one of the major methods to evaluate the construction quality of the slurry walls. Currently, different insitu permeability tests are recommended in various national and industrial codes, but the testing procedures are rarely mentioned. Furthermore, there are advantages and disadvantages among these different testing methods. This paper compares the advantages and their applicability of different insitu permeability testing methods. Related Articles | Metrics

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The Analysis of Human Error in Free Swell Ratio Testing YANG Hongying1, DU Minming2 2012, 26 (3):  101-103.  Abstract ( 2694 )   Save Free swell ratio is a key index for identifying expansive soil, which applies to cohesive soils with particle size less than 0.5 mm.  Since the testing does not involve complex equipment or testing procedures, it has been used widely in China to measure the expansive characteristic.  Many researchers has raised concerns about the uncertainties in the testing method, which may affect soil classification.  This paper provides a stateofart discussion on potential errors that may be induced throughout the entire testing procedure, based on a comprehensive literature review and a series of laboratory tests. Related Articles | Metrics

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Research on Soil Improvement for Expansive Soil YAN Fei 2012, 26 (3):  104-105.  Abstract ( 2271 )   Save This paper presents the results of soil improvement for expansive soil using cementstabilization and limestabilization.  The effect of soil improvement on a medium expansive soil  from Nanyang is demonstrated by comparing the shear strength before and after the treatment.  This soil improvement method will have wide application to ditches and slopes constructed with modified expansive soil. Related Articles | Metrics

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Axial Capacity Testing on Short Large Diameter Piles with Expanded Base CAO Jianguang 2012, 26 (3):  106-108.  Abstract ( 2850 )   Save The large diameter short bored pile with expanded end has the cost advantage in site with a relatively thin compressible layer over the bearing soils. A case study is presented in this paper to demonstrate this application. The static load test indicates that the design is appropriate. Related Articles | Metrics

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Direction Shear Test Method and Its Applications YE Baihua 2012, 26 (3):  109-111.  Abstract ( 2667 )   Save The shear strength is an important mechanical property of soils and is an major parameters for the foundation evaluation and the bearing capacity. Its physical meaning is the maximum strength to resist the external shearing. The direct shear test is a conventional method to evaluate the soil strength. This paper compares different direct testing methods for different types of soil samples. Some testing details are also presented. Related Articles | Metrics

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The Application of Geotechnical Investigation in Railroad Subgrade Settlement GUO Yangsheng 2012, 26 (3):  112-114.  Abstract ( 2422 )   Save This paper presents a case history of a geotechnical investigation to identify the cause of railroad subgrade settlement. Methods used during the investigation involve geotechical boring inspection, dynamic CPT and laboratory testing. Related Articles | Metrics