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20 August 2019, Volume 33 Issue 4 Previous Issue    Next Issue

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Intelligent Control of Soil-Cement Mixed Column Installation ZHU Zhiduo1, WAN Yu1, GAO Bo2， HU Hongcheng2， ZHOU Hui2， LIU Jinping3 2019, 33 (4):  393-397.  Abstract ( 871 )   Save The current state of the practice of the installation of soil cement mixed columns has the following disadvantages: low level of automation; poor quality assurance and over simplified design and construction parameters. This paper presents the development of an intelligent controlled soil cement mixed column installation system as well as the evaluation of this automation system. The following results can be obtained: the intelligent soil cement mixed column installation system can remotely collect the construction parameters automatically. This system can automatically control the length, plumbness and cement ratio of the columns, therefore, the quality of the soil cement mixed columns is improved. The subsurface conditions can be determined from the electric current in the drilling system and the variable frequency slurry injection method can be introduced to enhance the ground improvement results based on the sitespecific conditions that the drilling rod encountered. Related Articles | Metrics

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Design Coordination Between Two Adjacent Deep Excavations with Different Depths HUANG Zhenbo 2019, 33 (4):  398-401.  Abstract ( 341 )   Save With the increasing demand of urban lands for the developments, more and more construction projects are close to the other building or municipal engineering construction sites. This paper introduces a coordinated design scheme of two adjacentdeep excavations. Based on the safety and the schedule requirements of the both deep excavations, the proposed design fully considers the convenience of their construction and avoids the construction interference from the beginning. Therefore, this project is proved to be a successful one. Related Articles | Metrics

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Construction Control Methods of Bored Concrete Piles in Waters WAN Ce, DENG Xianghui, WANG Rui 2019, 33 (4):  402-406.  Abstract ( 369 )   Save This paper presents a case history of bored reinforced concrete pile installation for a long bridge at the Historical City Upgrade Project near Kunming Lake Road South. The site has complicated geological and geotechnical conditions, construction difficulties were encountered during the bored pile installation. These difficulties were and necking of the boreholes and loose debris accumulated at the bottom of boreholes. Due to the size of these bored piles and a large quantity of concrete pouring is required, the integrity of the bore concrete piles was often compromised. The paper introduces the construction quality control measures that could minimizing these defects. These measures include ultrasonic integrity testing plus static loading test were applied on the selected piles. The test results indicate that the quality control measures were successful. Related Articles | Metrics

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Evaluation the Compacted Soil-Lime Mixed Column -Improving Collapsible Loess Soils in Pingliang Area LU Zhaosong1, ZHAO Guanghong1, WAN Qiwei1, XU Pengfei1, CHEN Long2 2019, 33 (4):  407-410.  Abstract ( 357 )   Save The Grades II~IV Collapsible loess soils are widely deposited in Zhuanglang County, Gansu Province, along the alignment of Construction segment of Pingtian of PingliangMianyangExpressway Project. The compacted soillime mixed column method was selected to effectively eliminate the collapse when wetted, to improve the bearing capacity of the improved soils and to minimize the potential differential settlement of foundations. The effect of the soil improvement method was first evaluated in stations between K112+262 and 292. The evaluation results indicate that, the compacted soillime mixed columns can effectively increase the natural unit weight of the collapsible soils, reduce the initial moisture content and improve the bearing capacity of native soils. The key points of the column installations and lessons learned during the construction are also summarized in the paper. Related Articles | Metrics

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Soil Improvement for a Relocation Residential -Building Project in Yellow River Fluvial Area NING Xiaokan1, FENG Qiang2, LI Dongdong2 2019, 33 (4):  411-413.  Abstract ( 442 )   Save A large relocation residential building development project in Yellow River fluvial area is on the soft subsurface soils. Under the design earthquake intensity, the subsurface soils are also susceptible to be liquefiable. This paper presents the selection of the soil improvement program that could meet the structural, loading and seismic requirements and is also cost effective, simple construction and meets the construction schedule. The owner and the design consultant should pay attention on the subsurface conditions and carefully select the ground improvement method(s). The contractor should follow the design criteria and the code requirements in the implementation of the ground improvement method(s). When an unexpected condition is encountered during the construction, the effective communications among the geotechnical investigation consultant, building design consultant and the owner are critically important. Related Articles | Metrics

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Slope Stability Analysis for a Spoil Site of Expressway in Mountainous Areas of Guizhou Province PAN Yuan1, ZOU Fei2 2019, 33 (4):  414-417.  Abstract ( 763 )   Save Landslides, debris flows, and other geological hazards induced by the spoil sites of mountain expressways were frequently occurred, which have become a serious safety concern in the highway construction. Therefore, to analysis and evaluate the stability of the spoil sites have engineering significance. A spoil site, which is on the 40 meters left at Station K65+000 of an Expressway in Guizhou Province, was presented as a case study. The stability of this spoil site was evaluated based on the field and laboratory geotechnical investigations and the limit equilibrium of rigid body method. The results indicate that, the spoil site was stable under various conditions include heavy precipitations. Other engineering recommendations, such as, improve the drainage system at the spoil site and cover the entire site with grass, are also proposed in the paper. Related Articles | Metrics

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Numerical Simulation of Influence of Foundation -Pit Excavation on Adjacent Subway Station XU Tengfei 2019, 33 (4):  418-423.  Abstract ( 340 )   Save With the rapid development of urban construction, urban planning adjustments have become more frequent, and the construction of the rail transit has become a common need for large cities. Deep excavations have a particularly complicated impact on the stability of adjacent structures and utilities. To analyze the impact of adjacent facilities due to the deep excavations has a significant importance in the safe project developments. This paper presents a case history of the deep excavation for the Honggutan Central Financial Street foundation construction. This excavation project was adjacent to the transfer station for Nanchang Metro No. 1 and No. 2 lines. The finite element method was used to quantify the hazards induced in the construction. The hazards that corresponding to each factor are evaluated separately. Related Articles | Metrics

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Influence of Pipe Pile Installation on the Deep Excavation Supporting Structures in Soft Soils ZHAO Hui 2019, 33 (4):  424-427.  Abstract ( 333 )   Save Pipe pile supported foundations are widely used in engineering construction due to its advantages of having large bearing capacity, small settlement, reliable pile quality and fast installations. More and more projects utilize the pipe pile supported composite foundations to control the settlement. However, using the pipe pile foundations as a settlement controlling measure in foundations in soft soils with deep excavation that requiring the internal strut supports is limited due to the constraints of construction equipment and space. This paper presents a case history of an underground roadway project in Qianhai, Shenzhen City. The influence of pipe pile installation inside of the deep excavation area on the lateral deflection of the supporting structure was evaluated through the numerical analysis using commercial software MIDAS. The analytical results are also compared with the site monitoring results. It is concluded that the pipe pile installation inside the deep excavation area could contribute the lateral deflection control. Related Articles | Metrics

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Design and Construction of a Deep Excavation Adjacent to the Subway Tunnel LI Lianghui 2019, 33 (4):  428-432.  Abstract ( 405 )   Save With the rapid development of urban rail transit, the deep excavations are usually adjacent to the active subway tunnels in the central urban area, the restrictive deformation demands opposed on these active rail tunnels must be met by the excavation activities to ensure the safety operation of the subway. Because of this high requirement on the deflection of supporting structures, the designing of excavation supporting structures is controlled by deformation not by strength. Combined with the practice of the deep excavation adjacent to a subway tunnel in Shenzhen central area, the design, construction and monitoring throughout the entire construction process are introduced, the construction of the deep excavation is simulated by the numerical simulation method. The deformation of excavation and its impact on the subway is also analyzed. The results of monitoring and analysis are compared and evaluated. The design analysis method and construction measures are further summarized, which provide valuable references for similar projects. Related Articles | Metrics

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Slope Stability Mitigation in Fenghuang Temporary Construction Waste Soil Receiving Yard YI Heng, MO Jinfeng, YANG Xuewen 2019, 33 (4):  433-437.  Abstract ( 489 )   Save In the Fenghuang temporary construction waste soil receiving yard, a large amount of construction waste soil and rock were piled for approximate two to three years and it is found that these waste soil and rock fills are currently still settling under the selfweight. The soil and rock across the receiving yard of 40 to 60 meters high are not homogeneous with a significant difference in the grain size and material properties. The upper waste soils and the original colluvial residual soils are also different in engineering properties. Under the heavy precipitations, a potential weak zone is easily developed at the boundary zone between the original soil and waste soils due to the accumulation of groundwater and triggers the geohazards, such as, landslides and local slides. This paper presents of case study of waste soil slope remediation after a brief introduction of the evolution of the waste soil receiving yard. The slope mitigation measures included antislide caissons, slope surface treatment, surface vegetation and improvement of drainage system. Related Articles | Metrics

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Geotechnical Investigation Drilling Methods in Well Developed Karst Terrain WANG Jian1,2, LONG Ju1,2, LI Yong1 2019, 33 (4):  438-441.  Abstract ( 486 )   Save Due to the hidden and heterogeneous characteristics of rock cavities in well developed karst terrain, the geotechnical investigation work in these areas is complicated and critically important. To ensure the investigation quality, accumulated geotechnical drilling in soil and rock experience and skills are necessary. This paper presents a geotechnical investigation case history of test boring drilling in New World 3F Contract Block Project in Guiyang. The frequently encountered issues in the testing boring drilling, such as, fluid leak and loss, drill bit jam, borehole caving, drill bit loss, ground subsidence surround borehole and low rock core recovery, are discussed int eh paper. Improvement methods are also proposed. Related Articles | Metrics

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Consolidation Characteristics of Red Clay in Guilin Karst Terrain HE Tianjie1,2, LIU Zhikui1,2, DONG Binghong1,2, LI Yiran1,2 2019, 33 (4):  442-445.  Abstract ( 373 )   Save The consolidation deformation properties of the red clay samples from Guilin karst terrain under the static load are evaluated in this paper and the results could provide reference for the engineering constructions in the same area. Undisturbed red clay samples from various depths were collected and onedimensional consolidation laboratory tested under various moisture contents and dry densities. The following conclusions could be obtained: The lowest coefficient of compressibility of red clay samples were found at the optimum moisture content with different dry densities. The moisture content and degree of compaction have influence on the consolidation properties of Guilin red clay. Related Articles | Metrics

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Analysis of Asymmetric Deformation of Deep Excavation in Soft Soils GU Shaofeng, ZHUANG Fusheng 2019, 33 (4):  446-450.  Abstract ( 399 )   Save Soldier pile with strut bracing is one of the most widely used deep excavation support method in the engineering practice. In densely populated urban area with tight land use restrictions for the developments, the stress acting on the proposed deep excavation supporting structures are usually unsymmetrical. This paper presents a case history of the evaluation of the asymmetric deformation in a Chakeng cut and cover tunnel deep excavation supporting structure for the GuangzhouFoshanJiangmen Rapid Pass Project. Factors that inducing the asymmetric deformation are evaluated throughout the construction monitoring data. A threedimensional finite element model was established for simulating the stress and deformation of the excavation supporting structures. The results indicate that, in soft soils, the active lateral earth pressures are close to the passive lateral earth pressures so that the supporting structures are very sensitive to the external asymmetric loading. The soil improvement such as, soilcement mixed columns inside the excavated area could effectively reduce the lateral deformation of the supporting structures. Related Articles | Metrics

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Seismic Response of Karst Area Tunnels under Different Slope Conditions LIN Xuebin, LIN Ping, CHEN Long 2019, 33 (4):  451-454.  Abstract ( 377 )   Save Compared with structures that above the ground, the underground structures have a better seismic resistance. However, in recent years, it was proved that, under the seismic conditions, tunnel structures in karst geological conditions might still potentially have serious damage. Further, the degree of earthquake induced damage might also vary with the topography adjacent to the tunnel structure. The seismic response of a tunnel in karst terrain in Fujian was numerically simulated by using the twodimensional finite element analysis using a commercial software ABAQUS. The response of tunnels under seismic conditions with different slope conditions are evaluated and the stresses displacements are monitoring points are presented. Related Articles | Metrics

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Bearing Capacity Studies of Red Clay and Gravel Mixed Soils in Guilin SU Yang, DU Ciyang, LIU Zhikui 2019, 33 (4):  455-459.  Abstract ( 448 )   Save The red clay and gravel mixed soils in Guilin area have the unique geotechnical properties and these soils attract the attentions from both researchers and practitioners. Currently, there are no code established for the red clay and gravel mixed soils in Guilin, it is necessary to perform bearing capacity studies for these soils form the engineering application point f view. This paper presents a case study of plate loading test results on red clay and gravel mixed soils in Guilin. There are differences in between the dimension of the plate in the static loading tests and the actual footing widths, the bearing capacity of the actual foundation should be empirically adjusted from the static loading test results. A numerical simulation using a commercial finite element software FLAC3D on the plate static loading tests was performed. The numerical analysis results are consistent with the loading test results. Related Articles | Metrics

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Liquid Index of Weathered Granitic Soil and Its State Boundary PENG Gongxun 2019, 33 (4):  460-464.  Abstract ( 479 )   Save In this paper, the influence of coarse grains (ds>0.5 mm) on the engineering properties of weathered granite soils and the calculation method of liquid index of weathered granite soil are discussed. The correlation between the liquid index IL and the standard penetration test blow count number N is studied. The liquid index value of the boundary point of the state of weathered granite soil is also developed. Two comprehensive classification methods of weathered granite soils are proposed: namely, simple synthesis method and comprehensive index method. These methods are also compared with the single N value classification method. The application of these two methods is demonstrated by an engineering case history. Related Articles | Metrics

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Research Status of Spatial Effect of Deep Excavations FU Hongmei1, ZHANG Yanyan2 2019, 33 (4):  465-470.  Abstract ( 754 )   Save This paper presents factors that affecting the spatial effect of deep excavations and state of the art of the deep excavations is reviewed from the numerical analysis, theoretical approach and engineering applications aspects. Both disadvantages and advantages aspects of the domestic sate of the deep excavation are also provided in the paper. The following conclusions can be obtained: the numerical analysis method is an effective tool studying the spatial effect of deep excavations by the validation of the numerical method is strongly influenced by the constitutive model and the material parameters; Majority of the theoretical approach on the spatial effect in the deep excavation are on the noncohesive soils or equivalent noncohesive soils converted from the effective internal friction angle. Further studies are needed for excavations in cohesive soils. The engineering applications indicate that the spatial effect can provide guidance for the construction. Threedimensional numerical analysis calibrated with the construction minoring can help understand the spatial effect in the deep excavation. Related Articles | Metrics

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Theoretical Model of Compaction Grout Considering the Soil Three-Dimensional Shear Failure LI Tiankun1, LIU Lu2 2019, 33 (4):  471-474.  Abstract ( 431 )   Save This paper presents a new theoretical model for the compaction grout is proposed based on the theory of the spherical space expansions and considering the effect of the threedimensional cone shear failure of soil. The formulas foe estimating the uplift force and grouting pressure are also provided in the paper. The suggested method is also compared with the results from ElKelesh’s method. The relationship between the radius of the grouting bulb and the grouting pressure is also established to predict the required grouting pressure at different soil depths. Related Articles | Metrics

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Numerical analysis of the Shear Strength of Reinforced Soil with Shredded Tire Chips DU Zhenjiang, LIU Wuchao 2019, 33 (4):  475-478.  Abstract ( 383 )   Save Extensive direct shear tests on the reinforced soil mixed with shredded tire chips samples and regression analysis on the results are conducted to evaluate the shear strength of the reinforced soils and for the numerical analysis. This paper presents the elastoplastic approach for the shear strength of the reinforced soils. Based on the multivariable regression analyses on the test results, the regression model was established and calibrated with the monitored data. The results indicate that the adding of shredded tire chips can improve the performance of the reinforced soil with higher strain at the failure, higher tensile strength and less lateral deformation. The calculated results of the regression model are in good agreement with the measured values. Which can be used as the basis for the numerical analysis and calculation of shear strength of reinforced soil interface. Related Articles | Metrics

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Analysis and Evaluation of Slope Stability by Engineering Geological Analogy LI Kui 2019, 33 (4):  479-482.  Abstract ( 1058 )   Save Slope stability analysis and evaluation methods include qualitative and quantitative evaluations. The engineering geology analogy method is one of the qualitative evaluation methods. Its essence is to sum up the experience of geotechnical engineering of existing slopes and apply it to the study of slope stability evaluation with similar conditions. It is an empirical method and widely used. This paper presents the case history of the stability evaluation of a slope in Leshan City, Sichuan Province. Basic characteristics of a target slope, including its scope, scale, shape, material composition and deformation characteristics, are first introduced. Then, the repose angle of the surrounding similar original slope and fill slope is determined. Finally, the stability of the slope is analyzed and evaluated by using the geological analogy method, in order to adopt engineering control measures and similar slope stability. Related Articles | Metrics

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Investigation of Mechanical Behaviours of Single Joint Rock Based on the Direct Element Method ZHANG Bingsheng 2019, 33 (4):  483-487.  Abstract ( 485 )   Save Jointed and fissured rock masses are frequently encountered in tunnel and slope engineering projects. The distribution and geometric shapes of these structural planes with discontinuities in the rock masses, especially, the incline angle of the joint sets, have significant influence on the mechanical properties of rock mass and therefore might impact the safety and stability of engineering structures in the rock mass. In this paper, numerical simulations by using discrete element method were performed to evaluate the performance of the single set jointed rock with various inclination angles. The results indicate that the strength of jointed rock is less than that of the jointless rock mass. With the variation of the joint angles, the strength values demonstrated a Ushaped variation. When the joint inclination angles were between 45 and 60 degrees, rock mass failure usually occurred along the joint plane. Otherwise, split failure with welldeveloped internal joints was often observed. Related Articles | Metrics

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Classification Method of Water Quality of Freshwater Lens in Coral Reefs and Islands LI Kunyao1,2, TANG Jianjian2, CHEN Yongjun3, ZHANG Chenyang2, ZHU Xu2 2019, 33 (4):  488-491.  Abstract ( 356 )   Save The freshwater lens below the coral reefs and island is a very important fresh water source, however, not many researches on this aspect are reported. The conventional classification borderline for the saline water is using the 600 mg/L chloride concentration. Due to the uniqueness of the freshwater lens underneath the coral reefs and islands, the conventional groundwater quality and seawater quality standards could not provide enough references for the theoretical study and practical applications. It is recognized that the single chloride concentration classification is unable to meet the investigation and evaluation of water quality for these freshwater lenses. This paper presents a new classification by clustering algorithm, which classifies each water sample by calculating the distance from each data point to the cluster center. The results show that the classification results using SpCond, ORP and Turbidity are satisfactory. Related Articles | Metrics

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Lateral Unloading Deformation Characteristics of Deep Excavation in Cohesive Soils TAO Yangping, HOU Dejun 2019, 33 (4):  492-494.  Abstract ( 547 )   Save Under lateral unloading conditions, the failure mode of deep excavations is significant different from that of under loading conditions. In the deep excavation supporting design and foundation construction, the paramount important issue is the safety. A series of undrained triaxial shear tests on undisturbed soil samples under K0 conditions were performed to evaluate the lateral deformation properties of cohesive soils. The test results indicate that, under the unloading stress path, the undisturbed soil samples were under axial compression at the failure state with a maximum axial strain of 2.6%, which is much less that at of in the conventional triaxial shear test on the same soil type. The critical unloading ratios of different soil types are similar, and the ratios demonstrate the normal distribution between 0.14 and 0.27. It is also found that the soil sample demonstrates a good relationship with the average consolidation pressures. Related Articles | Metrics

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Numerical Simulation and Stability Evaluation of a Tunnel Through Fracturing Rock Mass Zone WANG Jian 2019, 33 (4):  495-499.  Abstract ( 389 )   Save This paper presents a case history of numerical simulations of a completed Yaozhai tunnel through the fracturing rock zone construction process. The numerical analysis derived deformation values are compared with the monitoring measured values in the different construction process. The influence of fractured rock mass zone on the tunnel stability was also evaluated and recommendations for the appropriate tunnel supporting method were also provided throughout these evaluations. The results indicate that, the presence of the fracturing rock mass zone indeed has an adverse effect on the stability of the rock mass surrounding the tunnel. Especially, stress concentrations were identified at crest and shoulder of the tunnel. Therefore, these locations should be closely monitored, and the geological predictions should be performed at the excavation area. Both initial and secondary liners should be strengthened for the construction and operation safety of the tunnel. Related Articles | Metrics

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Deformation Monitoring and Evaluation of a Rock Socketed Slurry Wall in Suzhou Metro SHE Haiyang 2019, 33 (4):  500-503.  Abstract ( 351 )   Save Under the complex soil and rock geological and geotechnical conditions, both the bearing and deformation characteristics of the rock socketed slurry wall are significantly different from those conventional slurry walls. This paper presents a case history of construction monitoring of a rock socketed slurry wall in Suzhou Metro No.3 Line project. The paper evaluates the construction monitoring data for the rock socketed slurry wall under different construction, geotechnical conditions and various supporting conditions. The deformation of this rock socketed slurry wall is summarized and the depth into the rock socket could therefore, be optimized for the future similar projects. Related Articles | Metrics

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Field Testing and Analysis of Vertical Resistance of Bored Piles in Soft Rock in Chengdu ZOU Li1, LI Zhaoying2, XIAO Shiguo2, SONG Qian2 2019, 33 (4):  504-509.  Abstract ( 445 )   Save Two static axial compressive loading tests on bored reinforced concrete piles that socketed into soft rock to obtain the vertical resistance characteristics of these bored pies. The shaft load transfer was measured by the instrumented fiber optic lines. Combined with the numerical analysis, the axial stress, shaft and tip resistances could be separated. The axial compressive static load test results on bored piles indicate that the shaft resistance increases with the depth to the pile tip; further, at the location of soil stratigraphy change, the obvious shaft resistance changes could be observed. The shaft resistance also increases with the increase of applied axial load. The increased shaft resistance are one meter above the tip of bored pile. Related Articles | Metrics

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Effect of Coarse Particles on Shear Strength of Peddled Silty Clay JIN Fuxi1,2, QIN Shuaishuai1,2, YU Zhengxing1,2 2019, 33 (4):  510-514.  Abstract ( 817 )   Save The geotechnical investigations indicate that the soil at the failure plane of a landslide consisted of gravelly silty clay. The shear strength of the gravelly silty clay soil has proved to be strongly influenced by the content of the coarsegrained gravels. Further, only direct shear tests were performed on soil samples from the failure plane and triaxial shear test were rarely conducted. In the conventional engineering practice, portions of the coarsegrained soil were removed to meet the maximum grained size requirements in the laboratory direct shear tests. Therefore, the tested shear strength from the laboratory direct shear tests are usually deviated from the actual site conditions. Triaxial shear tests were conducted on remolded samples based on the grain size distribution of undisturbed samples from the landslide shear plane. Same triaxial tests were also performed on the remolded sample with coarsegrained soil removed to investigate the influence of coarsegrained soil on the shear strength. Test results show that: with the gradually reduce coarse particle size, the tested cohesion of the gravelly silty clay samples first increases then decreases; The internal friction angle, the trend shows an decrease with reduction of the coarsegrained soils. Related Articles | Metrics

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Experimental Study on Unconfined Compression Strength of Different-age Lacustrine Soft Soil Stabilized by GGBS LI Yufei, ZUO Shuangying 2019, 33 (4):  515-518.  Abstract ( 519 )   Save Lacustrine deposited soft soils are widely encountered in the Binhu New District, Hefei City. Soil improvements are required for the new engineering development. This paper presents a new soil improvement method using Ground Granulated BlastFurnace Slag (GGBS) as an additive to solidify the lacustrine deposited soft soils. Extensive laboratory tests were performed on testing the unconfined compressive strength of the soil GGGBS mixed samples with different ratios (8% GGBS & 14%BBGS) and different curing ages (3 d, 7 d and 28 d). The results indicate that, within a practical mix ratio, the addition of GGBS will increase the strength of mixed soils and the strength also increases with the sample curing age. Related Articles | Metrics

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A Rapid Detection System for the Integrity of Cut-off Wall in Levees WANG Yuanming1, YAO Hailin2, CHE Ailan3, LUO Xingwen2, LU Zheng2, LI Heng1,4 2019, 33 (4):  519-524.  Abstract ( 407 )   Save The cut-off wall in levees play an important role in resisting floods and protecting the safety of human been and properties. A high-density surface wave method for the rapid detection of the integrity of the cutoff wall in levees is developed. The principles of the high-density surface wave method, integrity testing methods and data collections are first introduced. To improve the efficiency of the detection work, the vehicle mounted device with automatic triggering and automatic data collection systems. This device was tested and verified at various project locations. The results indicate that this method is an efficient integrity test system and is three to four times as fast as the conventional integrity testing devices. Related Articles | Metrics

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Application of TEM to Determine the Dimensions of the Abandoned Mine Voids ZHANG Jianzhi 2019, 33 (4):  525-527.  Abstract ( 359 )   Save This paper presents a case history of applying Transient Electric Magnetics (TEM) method in determine the dimensions of abandoned low content iron mine voids in Pingxingguan Area, Shaanxi Province. The electricity resistivity parameters were obtained by the TEM survey. Since the abnormal TEM characteristics can be detected in the abandoned mine voids, the targeted area was surveyed with a length of 50 meters as the emission TEM signals and the receiving side had a length of 20 meters. It is concluded that the voided area had obvious characteristics on the center loop attenuation curve response, resistivity sounding curve. These abnormal induced voltage multi-track curve and resistivity profile. Finally, the dimensions of the voids were interpreted through the resistivity profile. The boundary of the unfilled area in the high-resistance iron ore body provides a basis for the safety management of the abandoned mine voids. Related Articles | Metrics

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Evaluation and Quality Control of Plain Concrete Column Composite Foundations in Eastern Henan JIAN Linqing, XIE Rui, CHEN Jing 2019, 33 (4):  528-532.  Abstract ( 370 )   Save Testing methods that evaluating in the composite foundations are very important to ensure the quality control in ground improvement projects. The conventional quality control measure is the evaluating of the bearing capacity of composite foundations. In recent years, more and more testing measures and more and more quality control criteria have been proposed and applied in the practical projects. This paper presents two ground improvement projects that using plain concrete columns. Different quality evaluation criteria, such as, bearing capacity of composite soil and single columns, the strength of concrete column, the integrity of plain concrete column and characterization of soil among columns, are introduced and evaluated with the objective of evaluating the performance of composite grounds using testing data. Related Articles | Metrics