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30 October 2018, Volume 32 Issue 5 Previous Issue    Next Issue

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Manmade Soils and Lands--An Efficient Way of Massive Solid Wastes Disposals and Rocky Desert Treatment BAI Bing1,2， LI Xufeng3， CUI Yinxiang1,2 2018, 32 (5):  461-465.  Abstract ( 1233 )   Save This paper presents an effective way of manmade soils and manmade lands that could resolving the large quantities of industrial solid waste disposals and rocky desertification treatments. These types of wastes include, coal gangue, flyash and desulfurized gypsum. The manmade soils are the artificial mixtures of coal gangue, desulfurized gypsum and flyash in accordance to the desired gradation. The manmade soils can be applied to the rocky desertification area to create an area of manmade land. This method can resolve both the improvement of rocky desert and the disposal of bulk industrial solid waste and further to result in a vibrant recycling economy. Both the feasibility of manmade land and the critical aspect of this manmade soils  through the proper disposal of industrial solid waste are evaluated. Related Articles | Metrics

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Pullout Tests and Construction Technique of Buoyancy Anchor in Rounded Gravels in Chengdu TANG Yangui, YUE Dachang, LI Ming, YAN Beijing 2018, 32 (5):  466-469.  Abstract ( 1548 )   Save The rounded gravel soil deposits in Chengdu area usually have the characteristics of high groundwater. The underground structures will require a high design buoyancy. As a result, the single ground anchor will need to design for the higher ground anchor uplift capacity. However, the ground anchor is usually limited by the “critical length” and the increased uplift design load can be achieved throughout increasing the grouting diameter as well as improve the bond strength between soilgrout interface. The ground anchors, which were installed by conventional drill rigs, high pressure rotary jet grouting methods, were cyclic pullout loaded tested. The bond stress as well as the pullout failure modes of the uplift anchors were determined throughout the test results. The results indicate that the pullout resistance of high pressure jet grouted ground anchors in rounded gravel soil deposits have higher uplift resistance than the anchors with conventional grouting methods. Related Articles | Metrics

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Construction Monitoring and Analysis of Metro Station Supporting System TAO Song1, CHENG Kang1, SHEN Wei2 2018, 32 (5):  470-474.  Abstract ( 723 )   Save The case history of the monitoring of a metro station excavation supporting system in Wuhan is presented in this paper. The subsurface conditions, structural design, and the construction sequences for the station excavation are discussed. Throughout the monitoring data, the lateral deflection values of the soldier piles at different layers, axial forces in the inclined and vertical struts as well as ground subsidence values were compared with the analytical results. Factors that affecting the performance of the supporting system were evaluated. The results indicate that the stress and deformation of the supporting system are influenced by the dimensions of area to be excavated, construction conditions and embedment depths of soldier piles. Related Articles | Metrics

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Supporting Structure Foundation Construction of Cast-in-Place Box Girders Over Thick Soft Mucky Soils YAO Wuwen1, YANG Shengquan1,2, HU Yi1, WANG Xianqing1 2018, 32 (5):  475-479.  Abstract ( 755 )   Save One of the biggest challenges of large projects over soft mucky soils is the soil improvement to meet the post construction performance and safety requirements. Many soil improvement methods are available to strengthen the soft mucky soil strata with various advantages and disadvantages. This paper presents a case history of the soil improvements of the supporting structure foundations for the castinplace box girders using different methods. Throughout the settlement monitoring at different soil depths after the treatment, different soil improvement methods are evaluated. Related Articles | Metrics

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Evaluation of the Rehabilitation of a Creeping Mountain Tunnel Using Micropiles SU Xingju 2018, 32 (5):  480-483.  Abstract ( 608 )   Save The creeping hazards of mountain tunnels are reviewed in this paper. The micropile was used as rehabilitation method based on the project need with the combination of diverting the groundwater, and grouting around the tunnel. Both the numerical analysis and the construction monitoring results indicates that the micropile rehabilitation was effective and the creeping movement of the tunnel has converged. Related Articles | Metrics

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The Mitigation of a Steep Highway Landslide BAI Jianli, SHE Dongcheng 2018, 32 (5):  484-486.  Abstract ( 1009 )   Save Effectively mitigating the highway landslide can not only to ensure the smooth flow of traffic and reduce the potential economic and property losses, it can also improve the compromised ecological environment. The popular highway slope mitigation methods are Soft Net System (SNS), ground anchor with netting and shotcrete system and sliding resisting caissons. The sliding resisting caisson method has the advantage of applicable in landslide with different conditions, short construction schedule and fairly good results and has been used as a major landslide mitigation tool. This paper presents a case history of the evaluation of a highway landslide. Different mitigation methods are compared based on the sitespecific conditions and the sliding resisting caisson method that combined with ground anchors and retaining walls were selected. The results are satisfactory. Related Articles | Metrics

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Integrity and Mitigations of Static Pressed-in Pre-Casted Prestressed Concrete Pipe Piles with Defects SUN Chunli1, ZHAO Yubo2, LI Zhiyan3, ZHANG Jun4 2018, 32 (5):  487-489.  Abstract ( 712 )   Save The static pressed-in pre-casted prestressed reinforced concrete pipe piles have become increasingly popular due to their advantages of short construction period, applicable to a wide range of soils and minimized noise. The pile installation induced defects are unavoidably existed despite the effective quality control and quality assurance measures applied in the construction. This paper presents a case history of defect mitigation of pre-casted concrete piles installed in the third relocation residential district for the West Highspeed Rail Passenger Station Project in Jinan City. The defected pre-casted concrete piles are evaluated and categorized. Recommendations are proposed for piles that above the desired pile tip elevation, axial capacity that lower than the design value and piles having integrity concerns. Related Articles | Metrics

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Optimum Selection of Fracturing Method through Analysis of Splitting Pressure in Tahe Oilfield SONG Zhifeng1, MAO Haijun2,3 , HUANG Luyun3 2018, 32 (5):  490-497.  Abstract ( 604 )   Save The splitting pressure is an important parameter in the oil extraction. Based on the analysis of influence factors of splitting pressure, seven fracturing methods used in the world are briefly reviewed. These methods are: hydraulic fracturing, geothermal fracturing, high energy gas fracturing, foam fracturing, supercritical carbon dioxide fracturing, acid fracturing and liquid nitrogen fracturing. Key factors that causing the splitting in each method and their advantages as well as disadvantages are also presented. Based the geological conditions in the Tahe oilfield, four applicable fracturing methods are selected. Related Articles | Metrics

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Soft Soil Improvement at an Airport Runway Under Operation LI Changzheng1, FANG Ze2, REN Jiali2 2018, 32 (5):  498-502.  Abstract ( 898 )   Save A soil improvement work was performed at end of runway under operation for the runway extension project. The constraints for the construction activities were, short effective working time windows, restrictive requirements for the equipment and operation headroom, adverse night working environment, high quality requirement on the post construction performance for the extended runway after the soil improvement. This paper presents a case history of a soil improvement work performed at the end of an active runway. The vacuum preloading method was able to be applied at the ends of the operational runway with active air traffic. The bearing capacity of the improved soft soils is evaluated. Construction measures and procedures applied in the soil improvement work are also reviewed in the paper. Related Articles | Metrics

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Safety Control of a Multiple Return 500 kV Submarine Cable Landing Project ZENG Qinghe1, WANG Yadong2, SU Dingli3 2018, 32 (5):  502-505.  Abstract ( 843 )   Save The safety control in the multiple return 500kV submarine cable crossing and landing project is one of the critical issues to be solved in the submarine construction engineering. However, the state of the art aspects of the submarine cable landing procedures are still mainly based the cable installation experience developed on land, which are not enough to meet the requirements in the submarine construction engineering practice. This paper presents a case history of the installation a multiple return submarine cable project crossing a strait for the electricity transmission. The subsurface geological as well as construction logistic conditions at the cable landing site are evaluated and the impact of the highway construction along the shore line on the underneath cables are studied. The isolation measures provided by the large span girders and the energy dissipation measures provided by the cable tranches are recommended for the safe construction and operation of the landed submarine cables. Related Articles | Metrics

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Numerical Analysis and Monitoring of the Effect of a Deep Excavation Near the Operational Regional Metro Tunnels WAN Beijing1,2， ZHAO Shi3 2018, 32 (5):  506-509.  Abstract ( 506 )   Save The regional metro tunnel is expected to have deflections as results of the nearby deep excavation activities and therefore induce an adverse effect to the safe operation of the metro cars. This paper presents a case history of the excavation near Nanchang Rail Transportation No 1 Line. The measures that were used in the construction to reduce deflection in the operational tunnel are discussed. The construction monitoring results are compared with the numerical results. Related Articles | Metrics

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Desalination Process of Calcareous Sand under the Electrical Field CAO Meng1, ZI Min2, YIN Juan3,4，CHEN Weijun3,4, YAO Ruidan4 2018, 32 (5):  510-513.  Abstract ( 563 )   Save The scarcity of freshwater at coral reefs and islands receives more and more attentions. The precipitation on the coral islands and reefs is one of the major freshwater source. The freshwater lenses formed by the natural precipitation is relatively thin and take a long time to recharge.  This paper presents a laboratory study of desalination of seawater under an electrical field. The precipitation process was simulated by the distilled water. Three electrical fields were used in the study; 0.833C/cm, 1.667V/cm and 2.500 V/cm. Three precipitation intensities were also set; .0303ml/min/cm2, 0.0455ml/min/cm2 and 0.0606ml/min/cm2. The results indicate that, under the electrical field, the degree of desalination is higher than that of under the natural conditions. The highest desalination was found under an electrical field of 1.667V/cm and a rainfall intensity of 0.0606 ml/min/cm2. Compared with ears near the cathode, higher degree of desalination was found at areas near anode. When the voltage gradient is 2.5V/cm and the rain intensity is 0.0606ml/min/cm2, the intermediate point has the strongest desalination capacity. Related Articles | Metrics

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Experimental Study of the Influence of Moisture Content on the Soil Arching in Sandy Soils ZENG Chunmei, LIANG Haian, CHEN Qiang, ZHONG Jiahua, YOU Zhichao， HU Qingbo 2018, 32 (5):  514-516.  Abstract ( 700 )   Save The soil arching is the result of selfoptimization and adjustment of the forces after deformation of rock and soil mass. The soil arching concept is widely used in various projects. The current researches on the soil aching are focused on the mechanical properties geotechnical materials, such as, cohesion and internal friction angle by the moisture content on the evolution of the soil arching effect. The model studies that the evolution of the soil arching can be divided into four stages: Initial Arching, Critical Arching, Failing Arching and Failed Arching. The moisture contents at each stage of the arching are studied. The test results indicate that the moisture content plays an important role in the soil arching effect in the sandy soils. When the moisture content in sand in small, the arching effect can be ignored. Related Articles | Metrics

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Analysis of the Pile Compressibility under Load Transfer Under Vertical Loading Conditions LIU Hongchao, SONG Pengbo, ZHENG Yunfeng, HAN Shuang, LIU Zhiyong 2018, 32 (5):  517-520.  Abstract ( 634 )   Save The pile head settlement consists of the compression value of pile shaft and the soil settlement at the pile tip. The coefficient of the pile shaft compressibility is a critical parameter of in determining the pile shaft compressibility. This paper compares the measured coefficients pile shaft compressibility with the values that recommended by the construction code. It is concluded that the measured values might significantly different from the code recommended values. Factors that affecting the coefficient of the pile shaft compressibility are evaluated and the vertical load transfer function along the pile shaft is introduced to estimate the coefficient of pile shaft compressibility using the ratio of pile length to diameter and ratio of pile head loading to tip loading. Related Articles | Metrics

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Study on Numerical Simulation of the Optimal Pilot Width an Underground Pedestrian Pass DUAN Gonggao, TANG Hui, DONG Wenbao， XU Feng 2018, 32 (5):  521-523.  Abstract ( 567 )   Save This paper presents the numerical analysis results of the effect of pilot pass width on the subsidence of the street by using the construction of an underground passage of Xiongchu Street in Wuhan. The objective of this numerical study is to minimize the ground subsidence and simplify the underground excavation sequence. Different pilot widths are numerically studied in pilot passes No. 4 through No. 7. It is concluded that the pass widths in Pilot nos 6 and 7 meet the ground settlement criteria by Pilot No. 6 has the best simplicity. As a result of this study, the pass width and excavation sequence of Pilot No. 6 was selected. Related Articles | Metrics

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Influence of Sand and Fly Ash Contents on the Properties of Guilin Red Clay Mixtures TAN Jinghe1,2 , SUN Jiansen1,2 , LIU Huiqiang1,2 2018, 32 (5):  524-527.  Abstract ( 552 )   Save The effect of sand and fly ash contents on the Guilin Red Clay mixtures was studied throughout the direct shear, California Bearing Ratio (CBR) and scanning electronic microscope tests. The following conclusions can be obtained: For the direct shear tests, the strength of the Guilin Red Claysand and fly ash mixtures has no significant difference at early curing age of the mixtures. With the curing age, the shear strength will increase and approach to a stable value. The optimum mixture contained 20% sand and 10% fly ash. In the CBR tests, the additives can effectively increase the CBR values and reduce the amount of the expansion. The microstructure study indicates that that additives change the microstructure of the Guilin Red Clay soils and improve the strength and stability. Related Articles | Metrics

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Inverse Analysis of Tunnel Surrounding Rock Parameters Based on Displacement Back Analysis Method CHEN Chang, SUN Jizhu 2018, 32 (5):  528-531.  Abstract ( 574 )   Save This paper presents a case history of evaluation of the highway tunnel construction monitoring data at the crest of the tunnel. A threedimensional tunnel excavation model was established by using commercial software ABAQUS. Four different regions are divided in the tunnel model: undisturbed virgin rock mass region, pilot perforated pile reinforcement region, initial lining support region and double lining support region. The MohrCoulomb elastoplastic model was applied at the undisturbed virgin rock mass region and the elastic model was applied to other regions. The analytical parameters such as elastic modulus and Poisson’s ratio were calibrated with the monitored data throughout the back analysis. The analytical results provided an effective way of predicting the performance of the tunnel excavation. Related Articles | Metrics

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Stability Evaluation of Weak Slopes under Heavy Precipitation LUO Guangcai1, CHEN Miaoquan2, WEI Chunhua1, YONG Bang1, YANG Yong1 2018, 32 (5):  532-535.  Abstract ( 559 )   Save This paper presents a case history of effectively monitoring, predicting and mitigating the landslides of large highway slopes. The conventional limit equilibrium method and finite element method using strength reduction are used in the stability evaluation and the results are compared with the monitoring data. In the stability analysis, the limit equilibrium method was performed by using the commercial software GeoStudio. And the finite element simulation was conducted using ABAQUS software. The results indicate that, the precipitation has a strength effect of the stability of highway slopes. The deformation of the highway slopes can be estimated using the combination of limit equilibrium and finite element methods. Related Articles | Metrics

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Statistical analysis of accidents in Shanghai Metro Construction CAO Quan, GONG Shuhua, LI Peigang 2018, 32 (5):  536-538.  Abstract ( 1692 )   Save China has achieved unprecedented progress in the construction of urban rail transit over the past ten years, the driving speed and the number of rail lines are in the leading position in the world. However, various engineering accidents happened occasionally, and resulted in the property and human life loss. This paper statistically analyzes the operation accidents and several typical engineering accidents of Shanghai rail transit such as shield excavation accidents, deep excavation accidents, mine tunnel accident and the temporary supporting structural failures. The accident prevention measures for the construction safety are recommended for the rail transit projects. The research results show that there are many accidents and failure in Shanghai metro projects. The deep excavation supporting structure failures by seepage and slide inside the excavated areas. The construction technique also contributes to a large portion of accidents. Related Articles | Metrics

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The deformation Study of Deep Excavation in Soft Soil Improved with Various Cement Ratios LI Ming1, WU Bo1,2 , LI Chunfang3 2018, 32 (5):  539-544.  Abstract ( 549 )   Save The optimum cement content for the deep excavation in soft soils improved by the cement mixing method is usually selected by the experience and no technical bases are followed. This paper presents the results of the cement mixing research results. The unconfined compressive strength, cohesion, internal friction angle, deformation modulus of the soilcement mixing samples with various cement contents are studied. The lateral deflection of the deep excavation structure, ground subsidence with various cement content are numerically simulated. The results indicate that, the maximum lateral deflection the supporting structure and the ground subsidence reduce with the increase of the cement content. The soil improvement effect is also increase with the cement content. The laboratory study results were used in a soft soil deep excavation improvement project in Fuzhou and the results are satisfactory. Related Articles | Metrics

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Rock Fall Simulation Study and Mitigation Measures WANG Yu1，2, CAO Yunjiang2 2018, 32 (5):  545-548.  Abstract ( 680 )   Save Rock fall could repeatedly occur at the same location so that the installation of preventive measures at appropriate areas are very important.  The research on the rock fall mechanism requires the accurately simulation of the trajectory of the falling rock for the minimization of the potential rock fall hazard. The falling rock trajectories with different weights on the same slope are simulated by the ROCFALL software. The limits of the rock fall hazards can be estimated by the observation of the falling rock trajectory, kinematic energy and the rebound height. The preventive devices can also be appropriately installed by on the study. Related Articles | Metrics

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Slope Stability Analysis Using the Unified TripleShear Yield Criterion CHEN Te1, CHEN Guanghai2 2018, 32 (5):  549-551.  Abstract ( 556 )   Save This paper presents the slope stability evaluation results using the unified triple shear yield criterion. The Swedish Slicing Method with the unified triple shear yield criterion was used to estimate the factor of safety of the target slope. The results indicate that the stress state, shear strength of the soil as well as the middle principal stress coefficient can, at least some extent, affect the factor of safety. When the Lode Parameter is greater than zero, the resultant factor of safety decreases with the increase of the Lode Parameter. When the Lode Parameter is smaller than zero, the obtained factor of safety of the slope increases with this parameter. The factor of safety also increases with the cohesion, the internal friction angle as well as the middle principal stress coefficient. It is concluded that the factor of safety of the slope can be improved by considering the effect of the middle principal stress coefficient. Related Articles | Metrics

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Review of the SHPB in Rock Dynamics Research FAN Chao1,3, YU Kefu2, MENG Qingshan3, ZENG Weixing3 2018, 32 (5):  552-558.  Abstract ( 800 )   Save This article reviews the engineering significance of rock dynamics, test principles and methods of the Split Hopkinson Pressure Bar (SHPB) device and its research results of SHPB in the dynamic test of rock samples. It is concluded: ①SHPB is an effective design in the testing of mechanical properties of rock samples under medium to high strain rates due to its simplicity and accuracy; ②The specimen sizes and incident waveform have great influence on the accuracy of SHPB test results; ③ There is a strong positive correlation between the dynamic strength of rock sample and strain rate; ④ The free water in rock has a great influence on the dynamic strength of rock samples; ⑤The dynamic mechanical properties of rock samples change significantly within the conditions between extreme high temperature and extreme low temperatures; ⑥ The dynamic properties of rock samples under the coupled static and dynamic loading are different from those under the  uniaxial impact loading and SHPB cyclic impact tests can simulate the engineering properties of many deeply embedded rock mass. Finally, the recommendations and suggestions that could potentially improve the SHPB tests are also proposed by the authors. Related Articles | Metrics

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Application of the Integrated Methods in the Integrity Tests of the Cast-in-Place Reinforced Concrete Piles ZHAO Guanghui 2018, 32 (5):  559-562.  Abstract ( 527 )   Save The low stress reflection method is usually used in the preliminary screening of the integrity of the castinplace reinforced concrete piles, whereas, the sonic transmission method is generally used to locate the detailed defect within the concrete piles. The nondestructive testing methods results can be verified by using borehole coring and static load tests methods. The proper use of low stress reflection, sonic transmission, borehole coring and static methods in the quality assurance of the castinpace reinforced concrete piles can quickly and cost effectively locate the defects and their effect on the loading carrying capacities. Related Articles | Metrics

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Analysis of Large-Scale Direct Shear Test of Blast Furnace Slag and Fly Ash Mixture LIU Xiang1, ZHANG Chao1, XU Youjun1, MA Yanfei2 2018, 32 (5):  563-566.  Abstract ( 556 )   Save Large scale direct shear tests were performed on the furnace slags and flay ash mixtures backfill materials with three different moisture contents, 0%, 8% and 13% respectfully. The objective of the test study was focused on the effect of moisture contents on the internal friction angle of the backfill materials. The results indicate that the internal friction angle increases with the moisture content of the materials first, and then decreases. The internal friction angle reaches at the peak value at a moisture content of 8%. The tested cohesion, however, reduces with the increase of moisture content significantly and then turns to flat. It is concluded that the moisture content has the large impact on the cohesion of the backfill material but has the less effect on the internal friction angle. The maximum shear strength can be achieved at a moisture content of 8%. Related Articles | Metrics

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Permeability Tests of Clayey Silt under Different Seepage Pressures WANG Pei1, SHI Lei2, YAO Yuanhong1 2018, 32 (5):  567-570.  Abstract ( 750 )   Save The permeability of clayey silt is between that of clay and silty sand. The coefficient of permeability obtained by the conventional permeability test does not consistent with the field performance which might result in an adverse effect on the dewatering for the deep excavation. This paper presents a case history of permeability tests on undisturbed clayey silt soils in consolidometers and triaxial cells. The coefficients of permeability obtained under different seepage pressures, consolidation pressures and seepage paths are evaluated, and their effects are compared. The results indicate that the magnitude coefficients of permeability in the vertical and horizontal directions reduces with the increase of consolidation pressure. When the consolidation pressure is greater than the effective overburden pressure, the coefficient of permeability demonstrates a strong relationship with the consolidation pressure and the impact of seepage path is relatively small. Related Articles | Metrics