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21 April 2014, Volume 28 Issue 2 Previous Issue    Next Issue

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Effects of Deep Excavation on the Uplift Resistance of Underreamed Drilled Shafts CHEN Lu 2014, 28 (2):  1-04.  Abstract ( 2138 )   Save The uplift resistance of the underreamed drilled shafts is numerical evaluated in this paper. The results indicate that a large uplift is induced due to the rebound of the excavated area. The neutral point is near the bottom of the enlarge area. Under the excavation condition, the actual axial uplift load is far larger than the unexcavated condition, and the maximum uplift load is not at the top of the drilled shaft where the load is imposed. It is suggested that enough reinforcement is necessary to prevent the excessive tension in the shaft. The shaft resistance induced by excavation is large and cant be ignored. The enlarged bottom is taking about 37% uplift loading. The numerical studies verify the effectiveness of underreamed drilled shaft for the uplift resistance. Related Articles | Metrics

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Analysis of a Deep Excavation Site at Jiangan SUN Hai1,REN Jiangxing2 2014, 28 (2):  5-08.  Abstract ( 2012 )   Save This paper introduces the site geotechnical properties of a deep excavation project in Jiangan, Wuhan. Several common excavation supporting methods were compared and the gravity retaining walls consisting of cement mixed soil columns with the reinforcement of passive zone are selected. The results indicate that the design meet the code requirements. The project shows that the selected method has advantages of cost effective and safe construction. The construction recommendations are proposed in the paper. Related Articles | Metrics

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Dewatering Design for a Deep Excavation of an Industrial Facility XU Xiaochuan,YANG Zeping 2014, 28 (2):  9-11.  Abstract ( 1765 )   Save This paper presents the dewatering design results for a deep excavation of an industrial facility. The proposed dewatering is a well point system. The required flow from the well point is estimated by using Dupuit Formula. The number of well points and their locations are carefully designed. The decrease in groundwater level and its required pumping duration are also predicted. Related Articles | Metrics

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Design of Excavation Support Structures for Resettlement Housing Project of Qingtian Cultural  Exhibition Center DENG Weiping1,2，WANG Shibo3，LI Xiangbin1，HE Tao1 2014, 28 (2):  12-15.  Abstract ( 1871 )   Save The Qingtian Exhibition Center resettlement housing project is located in downtown Qingtian. The proposed site is occupied by a movie theater surrounded by the residential buildings and is not favorable for the deep excavation. Considering the poor conditions of engineering geology as well as poor hydrogeology, a careful design for the deep excavation supporting structures is required in order to ensure the safety, reliability and cost effectiveness during the construction. The stability of the deep excavation process was analyzed by commercial excavation software. Related Articles | Metrics

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Analysis of Seepage between Drilled Piles in the End Well of a Lager Deep Excavation SONG Jun 2014, 28 (2):  16-18.  Abstract ( 1512 )   Save The construction of large deep excavations become more and more frequent with the development of utilizing the underground space in the urban area. With relative long construction duration, adverse effects from the external and adjacent environment on the large deep exaction projects are inevitable. This is especially true for the prolonged precipitation season in Southern China, the stability of the excavation is often affected by the rainfalls. Based on the construction monitoring data, this paper presents the effect of the long duration rainfall and the leakage among drilled piles on the stability of the excavation and adjacent buildings. Related Articles | Metrics

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Application of the CFG Composite Ground in a Highrise Residential Building HAN Xiaolei,ZHANG Qiang 2014, 28 (2):  19-21.  Abstract ( 1832 )   Save The composite ground consisting of a mixture of Cement, Fly ash and Gravel (CFG) columns has its special advantages and receives a wider application in the construction of highrise buildings. This paper presents the CFG column application experience in Zhengzhou area. The bearing capacity and settlement analyses in the design aspects have compared with the national and industrial design code in the paper. Related Articles | Metrics

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Field Static Uplift Tests of Grouted Steel Pipe Piles MA Zhongzheng 2014, 28 (2):  22-25.  Abstract ( 1988 )   Save Field static uplift loading tests were performed on steel pipe piles with and without grouts in order to explore the effect of the grout on the uplift resistance and to obtain the static uplift loading test curves for piles in thick soft soils. The grouting zone on the axial uplift capacity of single piles was studied throughout the finite element analysis. The results indicate that the uplift loaddisplacement curve is "gradual change" type. The grout improves the surrounding soils as well as roughens the pilesoil interface. An increase of effective diameter can be found at the grouting holes and therefore, improves the uplift capacity of steel piles. Related Articles | Metrics

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Optimization of the Unloading Platform for Gravity Retaining Walls MENG Yaodong1,WANG Chenxi2 2014, 28 (2):  26-29.  Abstract ( 2149 )   Save The unloading (load reduction) platforms are usually placed behind the gravity walls in order to reduce the active earth pressures. Using a new earth pressure theory, the location of the unloading platform that resulting in the minimum overturning bending moment is optimized in the paper. The factors of safety for gravity walls with and without unloading platform are compared throughout the examples. The range of the location of the unloading platform behind the gravity walls are recommended in the paper. Related Articles | Metrics

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Construction Techniques of Highway Tunnels Through a Complete WeatheredFractured Fault GUO Jian 2014, 28 (2):  30-33.  Abstract ( 1845 )   Save A tunnel in Sanya City will align through a broken quartz fault. The excavation in tunnel indicates that surrounding rock in the fault is completely weathered and it has a poor stability property. The mud rush and severe deformation at the arch were encountered during the excavation and the original construction procedures could not be safely implemented. Based on the comparison of the construction supporting method, the following comprehensive technique is selected to control the deformation of tunnel: grouting with double grouts, middlesized pipe roof presupport and sixpart CRD excavation method with independent closure strong supporting structure in time. Threedimensional numerical method is performed to analyze the deformation of tunnel and the stress of the initial supporting structure and lining. The field monitoring result and construction effects have shown that the selected construction scheme can ensure the tunnel excavation safety. Related Articles | Metrics

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Construction Techniques of Dry Silty Sand Soils at theArch of a Large Section Tunnel HOU Gang 2014, 28 (2):  34-38.  Abstract ( 1725 )   Save Two different soil layers are deposited at a tunnel of Shangbai Passenger Rail for DatongXian Line. The upper dry silty fine sand soil is at the arch portion of the tunnel, and the underlying soil is classified as loess. The silty fine sand soil is characterized as low moisture content, uniform in grain size and it has a poor selfstability. The conventional permeating grout often results in a poor cementation outcome. Further, the grouting operation can often lead to the sand flow and even collapse incidents and a safe construction of the tunnel is jeopardized. After feasibility studies of several prelining mitigation methods, the horizontal jet grout methods followed by the threebench excavation were selected. The tunnel excavation process was also simulated with the three dimensional numerical method. Both the construction monitoring and the simulation results indicated that the adopted mitigation method of horizontal jet grout is a viable solution. Related Articles | Metrics

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Conceptual Design of Guangfu Road under Cross Tunnel SHI Taiwei 2014, 28 (2):  39-42.  Abstract ( 1786 )   Save Construction methods for a rectangular shielding tunnel are: Developing Parallel Link Excavating (DPLEX) Shield, Wagging Cutter Shield (WCS), MultiMicro Shield Tunneling (MMST) Method and Simultaneous Shielding and Concreting for large cross section rectangular tunnels. Compared with the circular cross section tunnels, the rectangular tunnels have the advantages of having shallow embedment depth, high space utilization ratio, and more cost effective. This paper presents a case history of the design and construction aspects of Guangfu Road under cross tunnel. Both circular and rectangular tunnel shielding methods are compared. The advantage as well as disadvantage aspects in the rectangular design and construction are also discussed in the paper. Related Articles | Metrics

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Cross Section of Lining Structure Optimization in Nanjing No. 3 Metro Line ZHANG Liangliang 2014, 28 (2):  43-46.  Abstract ( 1897 )   Save Studies of the performance of the tunnel lining structures under high water pressure is important to the optimization design of tunnel supporting structures. This paper presents a case history of the tunnel supporting study between stations Bingjiang Road and Wutang Village, Nanjing No. 3 Metro Line. The performance of the composite lining structure has numerically studied under the most unfavorable loading conditions. The results indicate that the cross section of the lining structure can be optimized. From the side wall to the top of the arch should be connected with circular arch with small radius so that the water pressures on the tunnel can be optimized. The small radius design also avoids the potential heave of the composite lining structure under the high water pressures. The resultant cost is not significant. Related Articles | Metrics

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Pipeline Excavation Instance In Silt Layer PENG Ying1，LUO Hongbing2 2014, 28 (2):  47-49.  Abstract ( 1590 )   Save Municipal pipe line installation projects are characterized to have a relative large excavation depth, quick backfill, short construction duration and long excavation support horizontal length. A case history of pipeline excavation project is presented in this paper to demonstrate the design, construction and construction monitoring aspects of the project site with a soft mucky soil layer. Related Articles | Metrics

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Experimental Study of Using CFG Columns Improving Subgradeof Lanxin Passenger Rail Line in Gobi Desert DONG Hui1，WANG Min1，NIE Zhihong2,MA Yiyue1 2014, 28 (2):  50-53.  Abstract ( 1800 )   Save To evaluate the effect of the proposed soil improvement, a series of tests has been performed on CementFlyashGravel (CFG) columns in the Gobi Desert of a rail road subgrade improvement project. These tests are: small strain integrity tests; coring through the CFG columns; axial loading tests on single column as well as column groups and settlement observations. The impact of the column spacing on the bearing capacity of the composite ground is studied. The objective of these tests and studies are for the later phase constructions and providing experience of subgrade improvement of railway in the Gobi Desert. The test results show: 1) Gobi soils have no obvious adverse effect on the quality of the CFG columns. Based on the integrity test results, a high acceptance ratio of 98.5% is observed. 2) Pumping concrete through a long distance using spiral pumping method is an appropriate technique for the CFG column installation. This has been verified through the sample cores from the installed columns. 3) The optimum column spacing in the Gobi Desert is 1.5 meter. When the spacing exceeds 1.5 m, a larger variation of composite capacity between the design and tested values are observed. 4) The composite ground has a small post construction settlement and a short duration for settlement stabilization is necessary. Related Articles | Metrics

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Subgrade Construction Techniques for Chengdu-Chongqing Passenger Rail ZHAO Huan 2014, 28 (2):  54-56.  Abstract ( 1625 )   Save This paper presents a case history of using fine grounded gravel as the subgrade fill for Chengdu-Chongqing Passenger Rail Line. The construction technique, quality assurance and construction procedure are also introduced. Related Articles | Metrics

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Analysis and Mitigation of a Landslide in Silty Clay Slope adjacent to a High Speed Rail LUO Xiyuan 2014, 28 (2):  56-59.  Abstract ( 1961 )   Save Landslide is a common geological hazard and it might potentially pose a significant threat to the safety of engineered structures. This paper presents a case history of a landslide hazard between a high speed rail stations DK 121+525 and +665. The mechanism, subsurface geotechnical conditions and backcalculation results of this silty clayey soil landslide are also discussed in the paper. The mitigation measures are: unloading, antislide caissons, and drainage installation. The two years operation after the mitigation indicates these measures are successful. Related Articles | Metrics

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Formation Mechanism and Control Measures of a Landslide in Nanba Township, Xuanhan Co. CHEN Sijiao, JIANG Yan, XU Min 2014, 28 (2):  60-63.  Abstract ( 2014 )   Save The geotechnical and engineering geology investigation aspects of a landslide mitigation project in Nanba Township of Xuanhan County are presented in this paper. The geological characteristics of the landslide are investigated. The evaluation work on the mechanism of the slide, slide controlling and triggering factors is conducted and the mitigation measures are also presented. The investigation and evaluation results indicate that the precipitation is the triggering factor and the planar slide is the result of excessive rainfall. The mitigation project is therefore focused on the sliding support and installation of the appropriate surface drainage system. Related Articles | Metrics

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Stability Analysis and Mitigation of a High Cut Slope in Wushan County,Three Gorges Reservoir Area GUAN Hongfei, XIAO Shirong, SONG Guilin, MING Chengtao 2014, 28 (2):  64-67.  Abstract ( 1916 )   Save There are many high cut and fill slopes created in the Phase IV Immigration Project for the Three Gorges Reservoir affected areas in Wushan County. The instability or excessive deformation of these slopes might post a potential hazard to the safety of infrastructures, buildings and human life. This paper presents a case study of the stability evaluation of a high cut slope for the site of Western China Teachers Residential Community in Wushan County. Factors that affecting the stability of this slope are discussed in the paper. The limit equilibrium and geological analogy methods are used in the stability evaluation and prediction work. The stability mitigation scheme is a combination of masonry gravity retaining wall, flattening slope, reinforced concrete grid beams and installation of drainage system. Related Articles | Metrics

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Optimization of Ground Anchor with Lattice Beam in MaZhu HighwaySlope Protections HUANG Huaixuan1， HUANG Zhigang1， WANG Bin2, ZHU Jiebing2 2014, 28 (2):  68-70.  Abstract ( 2214 )   Save Ground anchor with lattice beam is a slope stabilization technique that is the combination of deep strengthening and shallow erosion prevention. This technique has been widely applied in the highway cut slopes and embankments. In the lattice beam design, the proposed method uses the tributary area at each node at the cross. The slope is assumed to be the elastic soil foundation. The dimensions (spacing, sectional properties, cantilever condition) of the lattice beam can be determined by using the Winkler Elastic Theory. The analytical results indicate that the differences in shear force and bending moments are at side spans. The bending moment tends to be constant in the mid spans. The bending moment in the lattice beam is more sensitive to the dimensions comparing with the shear force. The suggested section properties of the lattice beams are: higher height to width ratio, smaller spacing, and the length of the cantilever beam should be 1/3 of the spacing. Related Articles | Metrics

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Preliminary Slope Stability Design for an Industrial Area AI Jianqiu，XU Xiang, ZHENG Shun 2014, 28 (2):  71-74.  Abstract ( 2172 )   Save The slope instabilities have been identified through the analysis of the existing data and the geological conditions of an industrial site. The stability analyses have been performed on typical cross sections and the preliminary slope stability design has been proposed. Related Articles | Metrics

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Numerical Simulation and field monitoring of Pileanchor Supporting Structure in deep excavation in Chengdu YANG Qing1, QIAN Xiao1, ZHU Lianhua2, FAN Kaiquan2, CHEN Huixian2 2014, 28 (2):  75-79.  Abstract ( 2317 )   Save The deep excavation receives more and more attentions with the development of the urban construction. This paper presents the numerical analysis using FLAC3D on a deep excavation in Chengdu City. The stress characteristics of ground anchors and soldier piles are studies and compared with the pobserved stress in the rebars and the horizontal displacement. The results indicate that the walers have strong constrains on the deformation of the soldier piles. The constrains induce the shear bending moment at pile head and affect the global stress field in the soldier pile; The bending moment in pile increases with the excavation depth; The location of ground anchors has significant effect on the moment in the pile; The maximum deformation along the soldier pile is at the middle and its location is lowered with the increase excavation depth. Related Articles | Metrics

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FLAC3D Analysis of a Deep Excavation Support Near Existing Building CAI Lei, AN Kang 2014, 28 (2):  83-86.  Abstract ( 2743 )   Save This paper presents numerical analysis resutls of deep excavation near existing buildings by using FLAC3D. The soil mass is simulated by MohrCoulomb model and the supporting structures are approximated by pile elements and ground anchor elements. The analysis results indicate that the prestressed ground anchors with soldier piles reduce the deformation of adjacent soil mass as well as the differential deformations at both sides of the nearby buildings. It is also concluded that prestressed ground anchors have significant effect on the horizontal stress in the excavated area. Related Articles | Metrics

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Simulation of Construction Process of Deep Foundation Pit inComplex Environment WU Qigang1, HE Na2, GUO Hongyan3 2014, 28 (2):  87-90.  Abstract ( 1888 )   Save This paper presents a case study of a deep excavation project in Shenzhen. The excavation process is simulated with threedimensional finite element analysis. The deformation characteristics of the foundation soil, supporting structures as well as the adjacent excavated pit under complex conditions are analysed and compared with the actual monitored values. The results indicate that the deformation increases with the depth of the dimension increase of the newly excavated pit. Therefore, the dimension change at each excavation stage should not be too large in order to induce the excessive deformation of the adjacent buildings. Near the excavated pit side, the deformation is relatively small due to the relatively low earth pressure changes. The comparison between the predicted deformation and the observed deformation values indicates that the numerical analysis is appropriate. Related Articles | Metrics

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Review of Single Pile LoadSettlement Predictions Based on of Transfer Function WAN Longxiang, ZHANG Qingwen 2014, 28 (2):  91-94.  Abstract ( 1573 )   Save Load transfer function method is widely used in the settlement prediction of pile foundations. It is a simple and practical method first proposed by Seed and Reese in 1957. The key aspects in the pile settlement prediction are to select an appropriate function and determine the parameters. A large quantity of research and testing are available.  It is suggested that the hyperbolic functions can better fit the nonlinear relationship between the pile and the surrounding soil. This article reviews the development of the shaft load transfer functions and its applications. The different expressions of the load transfer function under various constitutive models. The pile settlement is obtained through iterations by considering the deformation compatibility. Related Articles | Metrics

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Numerical Analysis on Behavior of Friction Pile Groups LIN Zhiyong1,2, DAI Zihang1 2014, 28 (2):  95-98.  Abstract ( 2009 )   Save Three dimensional numerical analyses are performed on a pile group model. Based on the analysis and comparison of a pile group testing model using numerical simulation in 3dimension, models of a single friction pile and friction piles group with embedded cap were built, and the similarities and differences of their behaviors were revealed by numerical simulation method. The results showed that under the same conditions, the type of loadsettlement curves and the development of the shaft resistance of the single pile and pile group foundations were respectively different; the upper loading was not simply allotted to each pile of the pile group averagely; a socalled "strengthen effect" of shaft resistance on each pile would occur near the end of the pile; and a socalled "weakeneffect" would be caused on the upper part of each pile. These laws revealed in the paper coincided with what people have known in theory or the measurements, which showed that analysis on the behaviors of friction pile groups by numerical simulation method was feasible, and could be references for the design calculations of pile groups. Related Articles | Metrics

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Discussions on Helical Compaction CastInPlace Piles XING Chaoyang 2014, 28 (2):  99-101.  Abstract ( 1865 )   Save The mechanism of the helical compaction piles is evaluated in the paper. The advantage aspects and the practical applications of the helical pile are evaluated. The insitu loading tests verified that the Helical Compaction Pile is highly vaiable. Related Articles | Metrics

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Review of the Extra Long Cast In Place Concrete Piles in Tianjin Area HAN Li1, SUN Lihua2 2014, 28 (2):  102-104.  Abstract ( 1606 )   Save The static loading tests are performed on the extralong cast in place concrete piles. The performance differences between the extralong piles and the conventional piles are evaluated. The characteristics and the loading transfer mechanism of the extralong piles are summarized in the paper. Related Articles | Metrics

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Stability of Surrounding Rock Mass in Shallow Tunnels under Unsymmetrical Pressures LEI Gang 2014, 28 (2):  105-108.  Abstract ( 1801 )   Save The appropriate evaluation of the shallow buried tunnels in weak surrounding rock mass under unsymmetrical loading conditions is significant important for the tunnel design and construction. This paper presents a case history of construction of Hongshigou Tunnel. The stress field, plastic zones as well as deformation field of the unsymmetrically loaded shallow tunnel is simulated under different soil cover height by numerical analysis. The failure mode of the surrounding mass is also studied. Related Articles | Metrics

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Numerical Analysis of Stress Distributions on a Pressurized Arch HAN Xiaolin 2014, 28 (2):  109-111.  Abstract ( 1736 )   Save The conditions that forming a pressurized arch are evaluated based on the MohrCoulomb criterion. The horizontal stress, the buried depth of tunnel and properties of surround rock mass on the performance of the pressurized arch are also studied throughout the numerical analysis. The results indicate that the horizontal stress and depth of tunnel embedment are the main factors affecting the pressurized arch. Among other factors, the horizontal stress has the significant effect of the shape and the location of the pressurized arch. Higher stresses in the surrounding rock mass, the location of the pressurized arch is closer to the tunnel and the steeper the pressurized arch is.  The lower the stress level in the rock mass, the pressurized arch will be far away from the tunnel and the flatter the arch. Throughout the study, the load intensity and its distribution on the supporting structure can be predicted and the supporting structure design can be optimized. Related Articles | Metrics

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Weathered Rock Mass and Supporting System Interactions of a Under Sea Tunnel Considering Rheological Effects HUANG Bo 2014, 28 (2):  112-116.  Abstract ( 2187 )   Save The subsea tunnel of Xiamen crosses four geologically fractured rock mass zones. The rock mass at the fractured zones is predominantly weathered broken and granite with strong rheological effect. The rheological tests are performed on samples from the fractured zones. Then, rheological constitutive model is established specifically for the weathering pockets in the rock mass. Finite element analysis that considering the interactions between the rock mass with weathered pockets and the supporting system is also conducted. The results show that the time related rheological effect of tunnels in fractured zones is significant and has to be considered in the tunnel design and construction. The thickness of the second lining supporting system in the weathered zone is appropriate. After the initial supporting, the second lining system should be immediately followed in order to ensure the tunnel construction safety. This paper also gives a method to determine the deformation rate of the rock mass and a method for the deformation control during the construction. Related Articles | Metrics

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Grain Characteristics in Sandstone in Wunlong Group of Cretaceous Age at Tangjiawan, Yichang City LIU Li1， LI Rui1， ZHANG Xiaojuan1, WU Gaochang2 2014, 28 (2):  117-120.  Abstract ( 2201 )   Save The cretaceous age geological profile near Tangjiawan in Yichange City has been field sampled and descripted in order to evaluate the grain size sedimentary parameters of sandstone in this age. There are significant changes in the sequence of the cretaceous outcrops although the sequence is generally presented by mud surrounded by sand. The central bar and cross-bedding is common in the sandstone due to the dynamic sedimentary environment. The grain size parameters are consistent in all samples from sedimentary indicators such as, mean grain size, sorting coefficient, skewness and kurtosis. These are the strong and stable indications of the sedimentary hydrodynamic conditions. The overall bouncing in the all grain size groups in the sediment is very developed. The layer in this age is the most representative of the cretaceous braided river facies. Related Articles | Metrics

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Effect of Lignin Content on the Direct Shear Strength of Sprayed SoilBase Layer in Slope Restorations LI Ying, CHEN Jinhong, ZUO Shuangying, YE Mingliang 2014, 28 (2):  121-123.  Abstract ( 1859 )   Save Minimizing the soil erosion and maintain the ecological environment are the major objectives of the bioengineering restoration of slopes. This paper presents the stateoftheart of bioengineering methods in the slope stabilization applications. The sprayed soil base layers with lignin as a bonding agent technology is also introduced in the paper. The direct shear tests on lignin bonded soil base layer samples and the moisture content control of the base layer materials are examined. The feasibility of using lignin as the bonding agent instead of other bonding materials in the bioengineering method of slope stabilization and vegetation are also discussed in the paper. The optimum material ratios of bonding soil base layers using lignin is determined based on the testing comparisons. Related Articles | Metrics

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Field Studies of Soil Mixing Columns and Geogrid Applications in Mitigating of Differential Settlement at the End of Bridges HU Qizhi，XU Xuewen, YUAN Haifeng 2014, 28 (2):  124-128.  Abstract ( 1948 )   Save Bumps at both ends of bridges are common hazards in highway construction.  This paper presents a case history of using soil dry cement mixing column and geogrid for the differential settlement at bridge ends mitigations. The results indicate that: a gradual stress redistribution process exists in the fill embankment operation. The dry cement mixing columns carry the majority of the overburden loads and a soilcolumn interaction effect exists in the load carrying. The soil dry cement mixing column can effectively reduce the total and differential settlement in the improved area. The role of grogrid is to improve foundation soil bearing capacity and the global stability through the load redistribution effect. The combination of the soil dry cement mixing column and geogrid can also effectively reduce the lateral movement of the bridge approaches. Related Articles | Metrics

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Geotechnical Investigation Aspects of Nanjing Metro ZHOU Chao1，HUANG Jianhua2 2014, 28 (2):  129-132.  Abstract ( 1798 )   Save With the urbanization development in recent years, the urban transportation is facing the challenge from the urban population increase. The urban rail transportation, as it is represented by the Metro and the light rail system, is usually a good solution to the public transportation in large cities. Due to the special engineering requirements of the Metro system and the geological variation along the subway lines, unique characteristics are existed in the geotechnical investigations for these projects. This paper presents the case study of Metro System between Stations of Xiongzhou and Phoenix Mountain Park of Pahse I of NingTian Intercity Light Rail Project. The geological stability, site evaluation, uniformity of subsurface soils and rock mass, special geomaterial as well as adverse geological condition aspects of the project are introduced. Design recommendations for the Metro System are also presented in the paper. Related Articles | Metrics

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Stability of High Open Pit Rock Slopes under Blast Loading ZHANG Deng1, 2, JIAN Wenbin1, 2 2014, 28 (2):  133-137.  Abstract ( 1760 )   Save Instabilities are prone to be induced under the blast loading for the high rock cut slopes in open pit mines. An improved method, which considering the frequency effect of the seismic inertia, is used in the time history analysis of the rock slope stability under the blast load. Combined with kinematical method, limit equilibrium method and numerical method, a comprehensive evaluation method for the cut slope stability was proposed. The improved method was applied to evaluate a rock slope of a tungsten mine. The results show that the higher the vibration frequency is, the more the safety factor decreases. But the higher the vibration frequency is, the faster the dynamic response attenuates and the extent of the safety factor reduction is limited. The time history curve of the safety factor of planar and wedge failure calculated by limit equilibrium method fluctuates around the static safety factor. The minimum value of the safety factor is 1.3, which is in accordance with the results of the FEM method. All of these indicate that the general failure of the slope is unlikely, but toppling or rockfall failure of small scale is probable. Related Articles | Metrics

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Experimental Study of Stress Relaxation Characteristics of Regular Rock Mass Discontinuties ZHOU Wenfeng1, SHEN Mingrong1,2 2014, 28 (2):  138-141.  Abstract ( 1426 )   Save Stress relaxation is one of the common rheological characteristics of rock and soil materials. The stress relaxation has important effect on the longterm stability of underground structures. In this paper, the stress relaxation phenomenon is studied as a separate research object. Throughout the shear stress relaxation test of regular discontinuities, the mechanical features of the structural planes are examined. The test results are simulated with Burgers model to reflect the stress relaxation characteristics of regular rock mass discontinuities. Related Articles | Metrics

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Skid Test Study on Interface between Crushed Stone and Concrete HAN Xiaolei, WEI Lei, WANG Haigang, ZHANG Dongdong 2014, 28 (2):  142-144.  Abstract ( 1461 )   Save Using the crushed stone as a sliding isolation material for rural lowrise buildings has a research significance. The inhouse made large simple shear device is used for the studies of frictional behavior between single crushed stone grain and the concrete slab. The horizontal shear sliding tests are performed with various grain sizes and vertical loads. The results indicate that, similar frictional performance can be found between crushed stone with various grain sizes and the concrete slab. The frictional resistance increases and reaches a stable level after a threshold displacement values is reached. The frictional resistance increases with the vertical load for stone various grain sizes. The coefficients of friction for crushed stone with different grain size vary in a certain range. Compared with small and large grains, the medium grain crushed stone has a smallest coefficient of friction and is a potential suitable cushion material for the seismic isolation purposes. Related Articles | Metrics

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Experimental Study on Dynamic Strength of Tailing Materials YU Hao, XU Muming, CHEN Hongquan 2014, 28 (2):  145-149.  Abstract ( 2406 )   Save The consolidated undrained cyclic triaxial shear tests are performed on samples from two different tailing materials. The shear strength, pore water pressures and the axial strain parameters of these samples were comparatively studied under various confining pressures as well as consolidation stress ratios. The results indicate that, under the cyclic loading conditions, if a consolidation ratio remains constant, the dynamic shear stress increases with the confining pressure. Under a constant confining pressure, the dynamic shear stress increases with the consolidation ratio. A rapid increase of the pore water pressure occurs at the early stage of the cyclic loading and the consolidation ratio has an obvious effect on the pore water pressure increase. The results also show that a parabola curve can reasonably fit the test results. Under a low consolidation ratio, a rapid strain change is observed at an axial strain of 1%. Related Articles | Metrics

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Limestone Characterization By Small Scale Model Tests LI Wenhui, GAO Meiben 2014, 28 (2):  150-153.  Abstract ( 1616 )   Save The selection of model material is critical in the physical analogy of geomaterials in small scale testing. After a review of the previous research results of selecting analogy material in the small scale physical modelling of limestone, this paper presents the physical modeling results using barite powder, bentonite, paraffin oil with different material ratios. The mechanical properties of the analog material are tested and the different material components on the mechanical properties are also discussed. The optimized material components in small scale modelling of limestone are proposed. Related Articles | Metrics

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Different Loading Procedures in the Horizontal Static Loading Tests on Single Piles BAO Yanjun1, TANG Dongmei2 2014, 28 (2):  154-159.  Abstract ( 1798 )   Save Two different loading procedures in the horizontal pile loading tests have been performed on the same pile type in the same subsurface condition. These two methods are: Maintained loading method and monotonic cyclic loading method. The different Q～y, y～lgt and H～t～Y0, H～ΔY0/ΔH curves are obtained under both loading procedures. Related Articles | Metrics

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The Deformation of the Movable Bearing Plates on the Uniaxial Compression Test Results of Intact Rock Samples HE Xiaoqing 2014, 28 (2):  159-162.  Abstract ( 1778 )   Save The effect of deformation of the bearing plates on the testing results of the laboratory uniaxial compression of intact rock samples are discussed in this paper. The proposed correction method can be summarized as following: Plotting the relationship between the measured incremental deformations, which is the measured differences under the current applied pressure, P and the previous pressure, and the incremental applied pressures. The deformation under the first applied pressure can be estimated based on extrapolating the plotted curve; therefore, the following incremental loadings can be corrected accordingly. Related Articles | Metrics

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Frequency Domain Analysis of Ground Penetrating Radar in Detecting the Karst Rock Cavity under Pile Tips ZHANG Zhang1，SUN Tao1, LIU Jidong2, ZHOU Zenghui3, TANG Xinjian3 2014, 28 (2):  163-166.  Abstract ( 1750 )   Save Both theoretical and practical aspects of the application of Ground Penetrating Radar (GPR) in detecting the karst rock cavities underneath the pile tip are introduced in the paper. The GPR data interpretation improvements by using Ormsby Filtering Method and background noise reduction in the frequency domain are also studied. Related Articles | Metrics

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Application of Origin9.0 in the Blasting Vibration Monitoring Data Process TU Lidong1, CHENG Kang1，LIU Pan1, CAO Tianshu2 2014, 28 (2):  167-170.  Abstract ( 1957 )   Save The software Origin has powerful data process and graphic functions. This paper summarizes the simplified results of empirical formula for the blasting vibration velocity prediction. The builtin power function in the Origin was used in the data fitting process. The actual monitored data were processed can be referenced by other similar projects. Related Articles | Metrics