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20 October 2017, Volume 31 Issue 5 Previous Issue    Next Issue

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Application of Double-Row Piles withReserved Soil in the PassiveZonein a Large Deep Excavation inthe First Terrace of Yangtze River in Wuhan GUO Yun, MA Yun, LIU Youxiang, Ni Xin, LI Song, ZHU Jia 2017, 31 (5):  537-542.  Abstract ( 1142 )   Save The DoubleRow Pile with Reserved Soil in the Passive Zone technique was used in the supporting system for Wuhan Capitalmall Westgate large deep excavation project, which is in the first geological terrace of Yangtze River. Soils along the perimeters of the footprint was excavated first. When the foundations for the main structures were constructed, the remain soil in the center of the excavation was then removed by using the reactions provided by the superstructure foundations. This supporting system can effectively reduce the amount of internal supports and provide larger working zones for the soil excavation and hauling. The construction monitoring data indicate that the soils reserved in the passive zone have an obvious constraint to the lateral deflection of front row piles. In general, the the deformations in both the supporting structures and in adjacent structures were acceptable. Related Articles | Metrics

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Small Diameter Steel Tube as Supporting Structure for Manually Excavated Caissons LEI Yizhong 2017, 31 (5):  543-545.  Abstract ( 876 )   Save The small diameter steel tubes were used as a supporting structure of manually excavated caissons in mountain soft soil strata. The design and construction sequence of the small diameter steel tube supporting structure are introduced. The results indicate that this method can effectively reduce the construction time, and cost while increase the safety. Related Articles | Metrics

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Application of the Preloading Method in a Large Area Container Yard WANG Jian 2017, 31 (5):  546-548.  Abstract ( 1047 )   Save This paper presents a case history of preloading surcharge method used in the soil improvement of soft soils underneath a proposed large container yard in Jintang Island, Zhoushan City of Zhejiang Province. The design and construction aspect of the preloading surcharge method. The geotechnical instrumentation program included surface as well as layer ground settlement, layered lateral deflection and pore pressure dissipation. The vane shear test, standard penetration test and laboratory testing were used in the evaluation of the surcharging results. Lessons learned during the construction are also presented in the paper. Related Articles | Metrics

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Application of Vacuum Tube Dewatering Technique in Deep Aquitard Layers MIAO Wang, ZOU Jianfeng, ZHAN Zhixi, ZHANG Haifeng 2017, 31 (5):  549-553.  Abstract ( 1000 )   Save The application of vacuum tube dewatering technique was used in Contract Package IIB of water tunnel of the YellowRiverCrossing project in MidRoute of SouthtoNorth water transfer project. The principles as well as results of applying this dewatering method in the low permeability aquifer soils are introduced throughout theoretical approach, construction monitoring and laboratory testing results. The mechanism, range of applications and expected results are also evaluated in the paper. The results indicate that the vacuum tube dewatering method can be effectively applied in soils high water retention, such as, silty loam, silty clay, clay and mucky clay. This dewatering method can effectively drain the capillary and gravity water in the soil and accelerate the consolidation process in a relatively shorter time. It is also cost effective. Related Articles | Metrics

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Shielded Tunnel Excavation in Saturated Sand Underneath the Existing Buildings CAO Pengfei 2017, 31 (5):  554-557.  Abstract ( 881 )   Save With advantages of safe and wide range of applicable geological strata, the shielded tunnel excavation method receives wider applications. However, the soil disturbance during the tunnel excavation will result in the ground subsidence, especially, in saturated sand layers. This paper presents a ground subsidence prediction results of shielded tunnel excavation in the Nanchang Regional Subway System project. Both PECK method and finite element methods are used to predict the building settlement over saturated sand layers during the tunnel excavation. The results are compared with the construction monitoring results and found they are satisfactory. Related Articles | Metrics

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Application of Double-Row Piles in Deep Excavation Supporting -System of High-Rise Buildings FENG Hui, SUN Yong 2017, 31 (5):  558-562.  Abstract ( 1088 )   Save A local horizontal earth pressure estimation method is proposed based on the review of existing methods of estimating lateral earth pressure on doublerow piles. The proposed method considers the friction angles between the pile and adjacent soils as well as cohesion of soils. This method focuses soils between piles and after the doublerow pile structure and the angle of slip surface to the horizontal line is obtained through trial and error so that the active earth pressure on the doublerow pile structure can be derived. This proposed earth pressure method is based on the finite bar element theory and elastic beam theory and is applied in a case history to evaluate the effect of spacing between front and rear piles on the bending moment and displacement on piles. Related Articles | Metrics

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Deflection Analysis of Deep Excavation with SMW Supporting System WANG Zhiwen1,2， CHEN Zhibo1, YANG Jianxue3 2017, 31 (5):  563-567.  Abstract ( 968 )   Save A deep excavation using Soil Mixing Wall (SMW) method in Fuzhou City was monitored during the construction. The monitored data included: horizontal displacement and vertical settlement behind and in front of the SMW supporting system; stresses within the internal strut supports and groundwater level. Some of the practical conclusions can be drawn from the monitored data: the magnitude of deep horizontal displacement in the soil mass increases with the excavation depth as well as the density of the internal strut supports. The magnitude of horizontal and vertical deflections at the top of the excavation vary with the same relationship as the deep soil horizontal displacement. A concave shape of settlement curve at the ground surface was observed at the north side of the excavation and a triangular settlement shape was identified at the south side of the excavation. The magnitude of the settlement was also affected by groundwater fluctuations and a lapsed effect was found. The typhoon induced precipitation had a significant impact on the stress in the internal support and the deflection of the supporting system. Related Articles | Metrics

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The Settlement and Stability Analysis High Filled Embankments During Staged Construction TAN Zhiming, HE Jiecong 2017, 31 (5):  568-571.  Abstract ( 1147 )   Save High fill embankment is currently more frequently encountered in during the construction with the rapid development of urbanizations. The stability and settlement aspects of the high fill embankments are numerically analyzed by using the finite element method. The potential slip surface, maximum deformation when approaching the failure and the factor of safety are determined by the strength reduction method. Stability mitigation measures include stability berm in front of the embankment, dynamic compaction, ground anchor with grid beams and geogrid methods. Related Articles | Metrics

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Soil and Water Conservation Measures for Wind Farms in the Mountainous Terrains NIE Wenbo1, ZHANG Lijie2, XIONG Weiping3, LUO Jie2 2017, 31 (5):  572-575.  Abstract ( 1203 )   Save Due to the negligence at each stage of the wind farm project in mountainous terrains: investigation, design and construction, large areas of erosions and even landslides on the sloped surface are frequently occurred after heavy precipitations. These geohazards are adversely affected the safe operation of the wind farms. Factors that affect the erosions are evaluated and preventive conservation measures, such as, appropriate disposal of construction spoils; proper drainage system; slope stability measures are suggested. Related Articles | Metrics

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Strength and Deformation Parameters of Coral Sand Foundations from In-Situ Tests TENG Aiguo1, HUANG Junwen2,3, WANG Xin2,3, CHEN Pingshan2,3 2017, 31 (5):  576-578.  Abstract ( 1135 )   Save The physical and mechanical properties of coral sand are significantly different from those of quartz sand and the current strength and deformation parameters for the foundation design are established based on the land origin quartz sand and might not be applicable to the foundations on coral sands. This paper presents the heavy dynamic penetration tests, plate load tests and standard penetration results on a construction project in coral sand soils in Hainan. The relationship between the heavy dynamic penetration test blow counts (N63.5) and the deformation modulus (E0) of foundation soils, standard penetration test blow count (N) and the deformation modulus are established. Related Articles | Metrics

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An Innovative Seepage Mitigation Method for Sluices in Soft Soils LI Hongwen1, LI Xuemei2, DENG Chengfa1, PI Lei1 2017, 31 (5):  579-582.  Abstract ( 1110 )   Save For sluices in soft soils,it iscommon that different portions of the sluice foundations are improved with different soil improvement methods. Under the structural loadings, differential settlement might be occurred. Further, due to the fast soil back filling at both sides of a sluice structure, the induced differential settlement would result in the unintended vertical seepage around the sluice structure. Soils at the both sides of the structure might also be scoured away by the tidal wave action. The seepage around the structure is a potential safety hazard to the operation and need to be mitigated. An innovative sluice structure seepage mitigation method using expansive rubber at sides plus the chemical grouting in the middle to prevent the seepage in the vertical direction. The pressure split grout was also used to stop the leakage around the sluice structure. Related Articles | Metrics

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Compaction Grout and Quality Assurance of Industrial Building Above Abandoned Mines in Zhangqiu HOU Fang1, JIANG Wenfu2, MENG Yan2, SUN Wenlai2 2017, 31 (5):  583-587.  Abstract ( 914 )   Save The proposed industrial buildings in Zhangqiu City, Jinan, are located above an abandoned mine. The limits of the underground voids were determined throughout the conventional boring program and geophysical methods. The compaction grout was used for the abandoned mine voids treatment. The grouting holes primarily located within the void limits. At locations with drill bits lost and drilling water loss, grouting holes were more densely distributed. The relationship between the penetration rate of the grouting holes and the grouting quantities were statistically evaluated. The coring of the grouting column was used as a grouting quality assurance measure. Related Articles | Metrics

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Geotechnical Investigation of a 2×660 MW Power Plant on Coral Reef Sands in Saudi Arabia LIU Zhiwei, YANG Shengbin, CHENG Dongxing, HU Xin, LI Can 2017, 31 (5):  588-590.  Abstract ( 871 )   Save The subsurface soils underneath a proposed 2X660MW power plant consist of limestone of coral reef origin. In order to characterize the engineering properties of limestone of Red Sea coral reef origin, the geotechnical investigation program included field conventional test boring, plate loading test and acoustic velocity testing and laboratory unit weight, unconfined compressive strength testing.  This project provides a useful case history of construction on the coral reef limestone and significant amount of experience of geotechnical investigation, coordination among different disciplines and different stake holders as well as practical execution of technical plans are accumulated. Related Articles | Metrics

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Mitigation of Slide in Daylighting Rock Slopes JIANG Xuhui, LI Xieneng 2017, 31 (5):  591-593.  Abstract ( 903 )   Save Slidein the daylighting rock slopes are frequently encountered in construction projects. A daylighting rock slide in town of Hanjia is evaluated and the mitigation method is proposed. The rock slide mitigation method can also be used in similar projects. Related Articles | Metrics

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Effect of Groundwater Fluctuation on the Strength of Collapsible Loess YA Ruwen 2017, 31 (5):  594-598.  Abstract ( 835 )   Save This paper presents the geotechnical investigation results of the collapsible loess soil underneath the proposed Second Elementary School site of Irrigation District in Town of Tianyangshan, Wuzhong City of Ningxia Autonomous District. The effect of the groundwater fluctuation on the strength of the collapsible loess throughout the standard penetration test (SPT) and laboratory tests. The moisture content in the loess soil was closely monitored. The results indicate that, when the groundwater raise, the SPT blow count in the soil decreases and the soil strength significantly reduces. The compressibility coefficient of saturated loess is higher than that of nonsaturated sample. When the degree of saturated increases, the surface tension among soil particles, matric suction and cementation among soil particles reduce accordingly. In the practical design, not only the collapsibility of the loess should be aware but also the soften of loess soil when it is wetted. Related Articles | Metrics

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Approximation of Rankine Active Earth Pressure Distribution on Retaining Structures SONG Zheng 2017, 31 (5):  599-601.  Abstract ( 808 )   Save Rankine earth pressure theory is widely used in the practical engineering design due to its simplicity. However, when it is used in predicting lateral earth pressure in deep fills, the estimated excessive earth pressures will result in a noncost effective retaining structure design. Based on the Rankine Theory, the horizontal slice method is proposed in this paper to estimate the lateral earth pressure distribution on the retaining structures. Using an internal friction angle of 15 degrees, when the friction between retaining structure and soils is neglected, the lateral earth pressure has a nonlinear distribution in the vertical direction. The approximate lateral earth pressure distributions for cohesionless and cohesive soils are provided in the paper and can be used for the practical engineering design. Related Articles | Metrics

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Coral Reef Ecological Restoration Using MICP Method TANG Yang, YAN Yue, GONG Xiaolei 2017, 31 (5):  602-605.  Abstract ( 1073 )   Save The State-of-The-Art coral reef restoration methods are reviewed. The coral reef ecological restoration is proposed by using MicrobialInduced Calcite Precipitation (MICP) method. The effect of different concentration of various bacteria solutions and concentration of calcium ion on the cementation result are laboratory investigated. The results indicate that, MICP method can be used in the ecological restoration of coral reefs. The concentration of bacteria and cementation solutions have a significant impact on the cementation results. Appropriate concentration of calcium and bacteria will results in a lower porosity in the coral material and improved material uniformity. Related Articles | Metrics

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Correlations between UU Test Values and In Situ Test Results of a Marine Soft Soil WANG Zhenhong, CHEN Mei, ZHANG Kun, ZHU Xitao 2017, 31 (5):  606-609.  Abstract ( 880 )   Save Engineering properties of marine soft soils are critical to the costal engineering and construction. Difficulties are frequently encountered in testing the soft soil strength. Due to the sample disturbance, the laboratory tested values usually have low reliability but the insitu testing is difficult to perform under the marine environment. This paper presents the studies on the marine soft soil in a project in Hengqin Island, Zhuhai City. The undrained unconsolidated (UU) triaxial shear test results were compared with the undrained shear strength obtained from vane shear test results at the same depth and the tip resistance from the cone penetration test (CPT) results. Good consistency is obtained from the UU results and vane shear as well as CPT tip resistance. The UU values can be compared with the vane shear test results with a reduction factor. Related Articles | Metrics

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Fundamental Study of Black Sand Crust Cementation Using MICP in Artificially Made Land Projects XU Hongyin1, HE Xiaoqing1, YAN Yue1, GONG Xiaolei2 2017, 31 (5):  610-616.  Abstract ( 1377 )   Save In the artificial made land project, the soft marine cohesive soils usually require improvement and the vacuum preloading is a frequently used soil improvement method. Before the vacuum can be applied, a layer of black fine sand is applied over the soft mucky clay so that a working platform can be created for the construction equipment. This paper presents the cementation of black fine sand by using MicrobialInduced Calcite Precipitation (MICP) method to reduce the thickness of the sand without reducing the bearing capacity. The effect of solution set up time, concentration and the velocity on the MICP sand cementation is evaluated by analysis the calcium ion utilization, distribution of calcium carbonate in the solidified sand column and the unconfined compressive strength. The results indicate that it is feasible to use MICP method for the rapid sand cementation. The solidified sand column can reach an unconfined compressive strength of 1.91 MPa in a short period of time. The results also show that the unconfined compressive strength has an index relationship with the concentration of calcium carbonate in the solidified sand column. The best result from the solution with 3 hour set up time, concentration of 0.75M with a velocity of 10ml/min. Related Articles | Metrics

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Mud Flow Prediction During the Tunnel Excavation Using FLAC3D ZHAO Min, SUN Yong, WANG Zixu 2017, 31 (5):  617-622.  Abstract ( 815 )   Save Physical model tests usually could only monitor several key points in the tunnel excavation. The threedimensional numerical analysis can effectively simulate the entire stress and strain change in the surrounding rock mass, the seepage field in the karst rock solution channels. The groundwater and mud rush through the fill media of karstic bedrock during the tunnel excavation are analyzed in this paper. Related Articles | Metrics

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Field observation and numerical simulation of the Embankment with Pile Supported Frame Structures Under Backfill Loads HU Xiaoming, ZHAN Minjie 2017, 31 (5):  623-627.  Abstract ( 1050 )   Save Embankments with pile supported frame structures have been used in the levee construction over marine soft soils. The performance of this type of embankment under the backfill soil load is infrequently investigated. This paper presents the results of “Performance of Embankment with Pile Supported Frame Structure Over Soft Soils”, which was funded by Zhejiang Hydraulic Engineering Research Program. A threedimensional finite element model simulating the staged construction was established by using commercial software MIDAS GTS. The deformation and stress in the frame structure were compared with the construction monitored data. The deformations before and after the soil backfill operation were evaluated. It is concluded that the embankment with pile supported frame structure is a viable solution of the levee construction over marine soft soils. Related Articles | Metrics

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Stability Evaluations of Shallow Buried Highway Tunnels under Unbalanced Geostress with Different Traffic Lanes LIU Zhijun1, ZHU Kuzhu1,2 , WANG Yang1 2017, 31 (5):  628-632.  Abstract ( 903 )   Save The shallow buried tunnels under unbalanced geostresses in complex geological conditions exist uncertainties. Different traffic lanes in the highway tunnel will result in the change of stress and strain states in the rock mass. This paper presents the parametric studies of two through four traffic lanes of shallow burred highway tunnels under the same unbalanced geostresses by using FLAC3D commercial software. The effect of traffic lanes on the stability of rock mass during the tunnel excavation. The results indicate that, with the increase of traffic lanes in the tunnel, both the vertical and horizontal deflections in the rock mass increase. The pressures at the both sides, crest and bottom of the excavated tunnels are increasing with the increase of traffic lanes. The plastic zones in the rock mass of tunnels with all three different traffic lanes have extended to the ground surface with similar shapes. Tunnels with less traffic lanes are more stable with a smaller plastic zone. From the stress, strain plastic zone and deformation in the surrounding rock mass point of view, tunnels with three traffic lanes under the unbalanced geostresses will have a least performance and the tunnels with two lanes perform better. Related Articles | Metrics

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Factors Resulting Levee Instabilities from Numerical Analysis and Laboratory Test Results ZHAO Wenchao1, WANG Hanwu2, REN Jiali2 2017, 31 (5):  633-636.  Abstract ( 908 )   Save The instability of a Yangtze River levee was numerically evaluated with laboratory test results and historical data. The mechanical and physical differences of soil sample from crest, toe of the levee and from the bank of the river were evaluated. It is concluded that the hazards on the levee was caused by the differential settlement. The observed results are also in consistent with the numerical analysis results. Related Articles | Metrics

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Application of a New Constitutive Model in the Mitigation of Xiangjiapo Landslide LIN Sitian 2017, 31 (5):  637-641.  Abstract ( 848 )   Save Limit equilibrium method is a major analytical tool for the slope stability projects. Recently, an innovative approach to the slope stability problems, which is called progressive failure analysis method, has been proposed. This paper presents the comparative evaluations of Xiangjiapo Landslide by using the conventional and new methods. The conventional method could only describe the earlier portion of slope instability but the new method could characterize the entire progressive failure of a landslide. The results conclude that both the conventional and the new method can be used in the engineering practice and the new method has the advantage of characterizing the entire progressive failure of a landslide. Related Articles | Metrics

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Factors Caused the Dam Cracking of Kubia Hydropower Project GAO Xiaoyu 2017, 31 (5):  642-644.  Abstract ( 790 )   Save Cracks were observed at the roller compacted concrete dam of Kubia Hydropower Project. The evaluation indicated that factors causing these cracks include differential temperature inside the dam and ambient environment, concrete contraction due to the hydration, selfdeformation and the external constraint. The paper discusses these factors and crack mitigation as well as prevention measures are proposed. The results indicate that these measures are satisfactory. Related Articles | Metrics

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Planning and Development of Underground Space in CBD Chongqing South Bank Areas LIU Rongcan, YANG Yang, WANG Xianjiu 2017, 31 (5):  645-647.  Abstract ( 1122 )   Save This paper statistically investigates the stateoftheart of the underground space in urban area from the effect of environmental geology, footprint and vertical layout of the underground spaces. Aspects of embedment depth, embedment depth to span ratio, space height and span length ratio, supporting structure, surrounding rock mass, seepage and stability are statistically evaluated. It is concluded that the shallow embedded underground spaces are usually densely distributed but these have rare further development potentials. The medium and deeply embedded underground spaces have more development potentials. Related Articles | Metrics

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Aspects of Low Stress Integrity Testing on Large Diameter Long Bored Piles MA Jian， MENG Xinqiu， LIU Li 2017, 31 (5):  648-650.  Abstract ( 960 )   Save This paper presents low stress integrity test experience on large diameter long bored concrete piles supporting railroad bridges. Two frequently encountered issues are discussed: shallow deflect and weak reflection from the bottom of piles. To resolve these problems, different citation methods could be used for the integrity tests. The results indicate that appropriate high and low frequency stress waves used in the test can effectively overcome these issues. Related Articles | Metrics

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Effect of NaCl Solution on the Strength Parameters of Ningming Expansive Soils LIANG Puyuan, LIU Yukun, LIU Huiqiang 2017, 31 (5):  651-654.  Abstract ( 851 )   Save The Atterberg Limits and consolidated drained direct shear tests were performed on soil samples prepared from Ningming expansive soil slurries. This paper presents the effect of NaCl solutions on the strength parameters of Ningming expansive soils. The results indicate that, with the increase of Nacl concentrations, both the internal friction and the cohesion in the sample decrease. The liquid as well as the plastic index also decrease with the increase of NaCl concentrations. The reason for these changes might be explained from the point of NaCl solutions change the interactions among the clay particles and double electronic layer properties. Related Articles | Metrics