Table of Content

20 April 2020, Volume 34 Issue 1 Previous Issue    Next Issue

For Selected:

Download Citations EndNote Reference Manager ProCite BibTeX RefWorks

Toggle Thumbnails

Select

Technical Aspects of Non-Recyclable Ground Anchor Cable Removal GENG Xiewei 2020, 34 (1):  1-03.  Abstract ( 1338 )   Save Non-retrievable ground anchor cables are conventional cables, and the tension parts are mainly made of steel strands. After the construction of nonrecyclable anchor cables, it will have some negative impacts on the surrounding underground environments. These impacts mainly include: (1) the impact on the construction of the pile foundation in adjacent blocks; (2) the impact on the deep excavationactivities in adjacent areas; (3) the impact on the surrounding municipal construction; (4) the impact on the excavation construction of subway shielded boring machine; (5) the impact on the longterm planning of the city. There are some difficulties in the removal methods and techniques of nonrecyclable anchor cables, and few successful cases were reported. This paper demonstrates the method and the technical aspects of the nonrecyclable anchor cable demolition based on the analysis of an actual demolition project. Related Articles | Metrics

Select

Pressurized Chamber Inspection and Cutter Replacement with Shield Protection Slurry in Saturated Karst Terrain ZHANG Dewen, WEI Qingwen, HUANG Xing 2020, 34 (1):  4-08.  Abstract ( 381 )   Save This paper is based on the experience when excavating the waterrich karst stratum of the limestone section in the Jinan Metro R1 Line from Fengjing Station to Dayang Station. The application background, basic principle, main process and key technology for the pressurized chamber inspection using shield protection mud are introduced in details. By analyzing the experience for operation control, cutter selection, soil improvement, cutter replacement and equipment maintenance, some recommendations are proposed. This paper helps to solve the highrisk problems for the safe pressured chamber inspection and the effective cutter replacement in highly jointed/fractured and waterrich karst stratums. Related Articles | Metrics

Select

Optimization of Buoyancy Design for the Sports Ground of a Middle School DONG Peixin, YANG Haojun, KAN Shenglei, ZHANG Xiangying 2020, 34 (1):  9-11.  Abstract ( 495 )   Save The piled foundation for the sports ground of a middle school was planned to resist the buoyancy uplift forces. However, construction difficulties were encountered, and the piles could not be installed. This paper presents the construction phase design change of using fully grouted rock anchors to meet the uplift requirements. The rock anchor design considered the sitespecific conditions revealed in the geotechnical investigation report. The total uplift forces determined from the piled foundations are also applied in the rock anchors. The design analysis and the optimization process indicate that the utilization of rock anchors for the buoyancy design can effectively resolve the constructability issues of pile foundation and the rock anchors have the advantages of cost effective and fast construction. Related Articles | Metrics

Select

Experiments on Slope Reinforced with Micropiles with Secondary Pressure Grout QI Xuemei, CHEN He, LIU Tao, WANG Kangyun 2020, 34 (1):  12-16.  Abstract ( 606 )   Save This paper presents an investigation into the effect of secondary grout on the micropiles performance. A large number of in situ tests were performed on the slope stability mitigation reinforced with micropiles with secondary pressure grout. The characteristics of secondary pressure grout were evaluated. The results demonstrate that splitting pressure, continuous pressure and rocksoil cracking pressure can reflect the mechanisms and the effects of secondary pressure grout. These factors can be considered as the control indicators for the secondary pressure grout. The secondary pressure grout acting on the fully weathered shale formation can be divided into four categories: secondary pressure grout without splitting, secondary pressure grout with shortterm slurry injection, secondary pressure groutwithout crushing pressure and secondary pressure grout with crushing pressure. Related Articles | Metrics

Select

Horizontal Displacement Control of Supporting Structures for the Deep Excavations of a Metro Station WANG Zhengqing, GUO Yunhua, SHI Zhenyu, LI Xiaoxiao, WANG Tianliang 2020, 34 (1):  17-20.  Abstract ( 412 )   Save The control deformation in the supporting structures in the deep excavation is mainly determined through empirical methods and these experiencebased criteria could not meet the state f the practice requirements of the increasingly larger depth, span length and quantity of excavations. This paper presents a case history of the deep excavation support for the metro station of Fifth Route of Guanggu in Metro Line N. 11. Factors, such as, ambient temperature, construction activities as well as space effect, which might potentially affect the magnitude of the horizontal deflection in the deep excavation supporting structure, are evaluated. The results indicate that the lateral deflections are strongly affected by the ambient temperature and the adjacent construction activities. The space effect is a function of supporting structure type and excavation sequence. It has less effect on the lateral deformation control criteria. Related Articles | Metrics

Select

Hydrological Characterization of a Cross-Sea Tunnel and its Groundwater Inflow Quantity in the Tunnel Excavation Prediction LI Weijing 2020, 34 (1):  21-25.  Abstract ( 356 )   Save This paper presents the hydrogeological survey results of a proposed crosssea tunnel in Qingdao. After a brief introduction of the hydrological features such as, site geological conditions, groundwater characterization and distributions, the groundwater inflow quantity of land portion as well cross-sea portion during the tunnel construction are estimated, respectively. The results indicate that, the estimated groundwater inflow in land portion is less than 3.67 m3/(d·m） and this quantity has negligible adverse impact on the tunnel construction. However, the groundwater inflow quantity in crosssea portion is approximately between 0.92 and 19.73 m3/(d·m）. This inflow quantity belongs to the property of medium permeable soil stratum. Related Articles | Metrics

Select

A Case Study on the Mitigating of a Shielded Tunnel Excavation Hazard with Internal Steel Plate QU Ronghuai, LIU Wenjing, SUN Lei 2020, 34 (1):  26-29.  Abstract ( 372 )   Save With the increase of metro operation mileage and service time as well as the influence of adjacent projects, the number of various hazards in the metro shielded tunneling excavation arealso more frequently encountered. In this paper, the deformation of a shielded tunnel excavation segment in different soil and rock strata under the crest loading and side unloading conditions is analyzed by the numerical simulations. The stress and deformation of shielded segment before and after the reinforcement with the internal steel plate are compared. The correspondent mitigation measures for the various hazards in the shielded segment are proposed. Both the analytical and construction monitoring results indicate that the application of internal steel plate for mitigating the defected shielded tunnel segment is successful. Related Articles | Metrics

Select

Analysis and Mitigation of Adverse Settlement of Existing Railway Roadbed ZHANG Qianyi 2020, 34 (1):  30-32.  Abstract ( 667 )   Save This paper presents a case history of adverse settlement evaluation of the existing railway roadbed and its mitigation details. The factors that could result in the roadbed settlement and feasible settlement mitigation method are briefly discussed. The process of using the jet grout mitigating the roadbed was also numerically simulated with the sitespecific soil parameters. The following results are obtained: 1) if the significant permeability differences exist between the subgrade structure and the original soil, the presence of silty soils will likely induce in the differential settlement within the roadbed; 2) the raise of groundwater will soften the subgrade soils and increase the compressibility of the subgrade soils and then result in additional settlement; 3) When applying the jet grout method, the best result is at time the column jetting angle is 25 degrees; 4) When the  replacement ratio of the jet groutsoil is reached 20%, the best mitigation results can be obtained. Related Articles | Metrics

Select

Strength Characteristics of Fine Silty Sand in Yinchuan Plain HAN Li, XU Hanbao, CUI Zizhi, SHEN Suping, SUN Changhao, YAN Hao, YANG Longbo 2020, 34 (1):  33-36.  Abstract ( 635 )   Save The finesilty sand is widely distributed in the Yinchuan Plain with shallow deposit and large thickness. It is the main bearing layer for buildings with shallow spread footings. However, few mechanical properties test data available for the engineering projects reference. Therefore, considering dry density and saturation, the orthogonal test scheme wasplanned, and the strength characteristics of finesilty sand in Yinchuan Plain wasevaluated by laboratory undrained direct shear tests usingthe straincontrolled electrical direct shear instrument. Factors that might affect the strength properties and their significance of the fine silty sand were explored throughout the regression correlation analysis model. The following results can be summarized: The shear strength of Yingchuanfine silty sand nonlinearly increaseswith the increase of the dry unit weight and higher unit weight yields with higher shear strength. From the significance descent ranking are the dry density and the degree of saturation. In soil improvement projects using dynamic compaction, conventional rolling compaction and the displacement column methods, the dry unit weight can be used as the index parameter. For cohesion and friction angle soils, the impact of dry unit weight and the degree of saturation on the cohesion are higher than on the internal friction angle. It is also concluded that the regression model on the Yingchuan fine silty sand soils are successful. Related Articles | Metrics

Select

Discussion of the Analytical Methods of Internal Forces in Anchored Frame Beams WANG Chunguang, ZHU Shouzeng, LIU Yukun, PANG Banghui, HUI Yanglei 2020, 34 (1):  37-40.  Abstract ( 429 )   Save This paper introduces several conventional internal force estimation methods of the beam on elastic soils. The bending moment formula in the Two-Parameter Method is improved and the new internal force solution is obtained by assigning zero coefficient of foundation shearing in the beam on elastic soils. Four different approaches of obtaining the internal forces in a real project application and these methods are: HetenyiMethod, Infinite Beam Method, Initial Parameter Method and Two-Parameter Method. The impact of foundation shear coefficient on the internal forces in beam on elastic soils are also evaluated. Related Articles | Metrics

Select

Research Progress in Particle Morphology of Calcareous Coral Sand WANG Buxueyan, MENG Qingshan, ZHANG Poyv, 2020, 34 (1):  41-44.  Abstract ( 431 )   Save Unlike the common land originated quartz sandy soils formed by the weathering rock, the calcareous sand is formed by a long period of weathering of biological remains in the marine environment. Due to the uniqueness of its formation process, the calcareous sand retains some of the structure and component characteristics of biological remains, such as, calcium carbonate content>50%; irregular shape;easy to break; easy cementation of particles, high internal friction angle, high porosity ratio, large intergranular occlusion force, etc. The reason why it is different from the general continental and marine sedimentary objects in engineering mechanical properties is the two aspects; such as, composition and morphology. In this paper, the study of the particle morphology is also presented. Related Articles | Metrics

Select

Optimization of the Isolation Pile Arrangement for the Adjacent Pile Supported Bridge in a Fill Slope YI Lili, MA Yun, NIE Jun, LI Song, ZHANG Dele 2020, 34 (1):  45-49.  Abstract ( 381 )   Save To investigate the effect of isolation pile on the horizontal displacement,bending moment in piles that supporting the bridge structure and on the global stability control, thefinite element analysis was performed. The factors such as isolation pile length, pile cross section size, and distance to the piles that supporting the bridge structure, were analyzed in the numerical investigations. Results suggest that: 1) The isolation pile with large diameter has good protection effect on the bridge piles； isolation piles that are close to the toe of slope, it’s benefit to the global stability of the slope. 2) When the isolation pile length is 2~2.5H, the closer to the slope toe, the better the control effect on the horizontal displacement and bending moment in bridge piles. The more remarkable the control effect of the global stability of fill slope.3) The isolation pile length and the distance from the bridge piles are more efficient in controlling the bending moment than the horizontal displacement in piles that supporting bridge structure. Related Articles | Metrics

Select

Numerical Method for the Determination of Shear Strength Parameters of the Slip Zone SU Meixuan, LIN Zhiyong 2020, 34 (1):  50-52.  Abstract ( 590 )   Save In this paper, the basic principles of the numerical back analysis of slip zone soil properties are introduced. The finite difference plane strain model is used to back predict the shear strength parameters of a highway slope in the critical stability conditions. Two sections with the same distance from the main axis of the landslide are taken respectively. First, one set of the shear strength parameters c (or φ) is assumed, and the other set of parameters φ (or c) is repeatedly tested and adjusted until the numerical analysis reaches critical state. At the critical condition, factor of safety K=1 is assumed, a set of corresponding shear strength parameters is obtained. Several groups of corresponding c and φ values are analyzed repeatedly using the same method. Then the data of two sections are plotted in the same coordinate system, and the intersection point is the shear strength parameters of the slope. The results show that it is feasible to estimate the shear strength parameters in the sliding zone soil by the back analysis using the numerical simulation method. Related Articles | Metrics

Select

An Application of Deep Excavation Method LIAO Kunyang 2020, 34 (1):  53-56.  Abstract ( 394 )   Save With the development of urban construction, there are more and more underground projects being developed. The main characteristics of deep excavation are introduced systematically in this paper. The conventional deep excavation supporting systems are summarized: sloped excavation, soil nailing wall method, sheet pile support, diaphragm wall, inner support, anchored soldier pile support structure and composite retaining structure. The conventional bottomup construction method and the topdown construction method are the main construction techniques in the construction of deep excavation. The construction characteristics of the bottomup construction method and the topdown construction method in the deep excavation are summarized. The constructionsuggestions for the topdown construction method are provided for other similar projects. A case history of the deep excavation was introduced in this paper. The deformation and settlement curves of the diaphragm wall are analyzed, and the maximum deformation position and maximum settlement position of the diaphragm wall are determined. Related Articles | Metrics

Select

Bearing Capacity Determination of Basaltic and Clayey Alternating Deposited Strata LIU Junfang, NI Zaihe 2020, 34 (1):  57-60.  Abstract ( 438 )   Save Difficulties of determining the bearing capacity of basalt rock and clayey soil alternating deposit strata are frequently encountered in the geotechnical investigations. The stress field in the strong basalt rock overlying the weak clay soil layers will have a stress spreading effect on the underlying weak clayey soil layer and this stress spreading effect can be equivalented to the effect of bearing capacity increase in the clay layer. Correction factors are provided based the engineering experience for the practical engineering application. The empirical bearing capacity values were compared with the finite element analysis results. The comparative results indicated that the empirical relations is conservative and can be safely applied in the geotechnical investigations. Related Articles | Metrics

Select

Effect of Gradation Missing on the Shear Strength of Sandy Soils LI Zirui, HONG Yong, TANG Shaoshuai, WANG Luyang, LI Liang 2020, 34 (1):  61-64.  Abstract ( 348 )   Save The influence of gradation missing on the shear strength properties of sandy soils was investigatedthroughout the laboratory direct shear tests and discrete element simulation methods. The results of laboratory tests show that the missing of the particle gradation leads to different degrees of reduction in the shear strength of sandy soils, and the strength of soil samples without coarse particles has the maximum strength reduction. By establishing a PFC2D numerical model that matches the results of laboratory tests, it is a good complement to the inadequacy of mesoscopic parameters monitoring in laboratory tests, mainly on the force chain morphology, dilatancy characteristics and porosity evolution of soil samples after gradation deletion. The results also show that the coarse particles play a major role in the stress transfer and the local strain of the soil during the shearing process, while the filling of the fine particles helps to improve the stability of the sand force chain network. Related Articles | Metrics

Select

Effect of Dry Density on the Strength of Near Shore Samples MENG Ying, HOU Rui, WANG Daojin, ZHANG Xiang, HUANG Zhiquan 2020, 34 (1):  65-68.  Abstract ( 285 )   Save Shear strength is an important mechanical property parameter of soils. In order to investigate the influence of dry density on the mechanical properties of soft soil nearshore sample from Bohai area, the undrained unconsolidated direct shear tests wereconducted on the natural soil sample with different dry density. The influence of dry density on the cohesion and the internal friction angle of the unsaturated clay tests was evaluated. It is concluded that the shear strength increases with the dry density. Related Articles | Metrics

Select

Finite Element Study of the Influence of Horizontal and Vertical Sake on the Slope Stability HUANG Xing 2020, 34 (1):  69-72.  Abstract ( 433 )   Save In order to quantify the influence of horizontal and vertical seismic actions on the slope stability, a typical slope is taken as an example. The finite element strength reduction method was used to analyze the influence of horizontal seismic actions only, vertical seismic actions only, and combined horizontal and vertical seismic actions on the slope stability. The seismic actions in different seismic magnitude areas were also considered in combination with the relevant seismic codes of China. The results show that it is necessary to consider the horizontal seismic action in the area of earthquake magnitude 7 degree and above, and it is necessary to consider the vertical seismic action in the area of magnitude 9 degree. Related Articles | Metrics

Select

Unconfined Compressive Strength of Basalt-Glass Hybrid Fiber Cement Stabilized Crushed Stone Samples PENG Yifei 2020, 34 (1):  73-75.  Abstract ( 372 )   Save Cement stabilized gravel is a semirigid material obtained by adding cement and water to a certain grade of gravel.The stabilized soil has better water stability and frost resistance than that of lime stabilized soils. In recent years, there have been many researches on the nonlateral compressive strength of cement stabilized gravel mixed with single fiber, and there is less researches on the compressive strength of cement stabilized gravel mixed with mixed fibers. Therefore, in order to study the relationship between the unconfined compressive strength of basaltglass mixed fiber cement stabilized gravel and the mechanism of improving the stability. By changing the content of basalt fiber and the content of glass fiber in the cement stabilized gravel, the unconfined compressive strength of the 25 mm basalt gravel size mixed with 1.0‰ fiber and the 12 mm basalt gravel size mixed with 0.8‰ fiber will have a maximum unconfined compressive strength of 4.63 MPa. Related Articles | Metrics

Select

Unconfined Compressive Strength of Cement Improved Soil Samples Prepared under Various Conditions HOU Rui, WU Jiaqi, FAN Tiebing, LI Huan, LI Yunfei 2020, 34 (1):  76-79.  Abstract ( 599 )   Save Cement improved soil with various cement contents samples are prepared and unconfined compression tested using mucky clay from the near shore area of Bohai. The unconfined compressive strength values are obtained from samples prepared with four (4) different cement contents, two (2) different curing methods and wet cement and dry cement preparation methods. The test results indicate that the strength values of samples prepared with dry cement method are very scattered and have no relation with the cement content. The scattered strength values can be attributed to the unmatured sample preparation method. It is not recommended to use dry cement method for cementsoil construction under the similar conditions. At the cement content of 25%, the unconfined compressive strength values of cement improved soil samples prepared with wet cement method are much higher than those of prepared with dry cement method. It is suggested that when the cement content is between 23% and 25%, the wet cement method should be used in cement improvement method. Related Articles | Metrics

Select

Method of Determining the Graded Moisture Contents of Weathered Granitic Soils PENG Gongxun, CHEN Yongping 2020, 34 (1):  80-83.  Abstract ( 578 )   Save In order to solve the problem that the moisture content measuring with the washing method is distorted for coarse and fine particles of weathered granitic soils, a dry sieving method is proposed to measure the moisture content of various particles of weathered granitic soils under natural moisture content. The test process of this method comprises the following steps: crushing soil sample with natural moisture content; preliminarily sieving the natural soil sample into subsamples with different gradations; measuring the natural water content of each subsample; and then washing the subsamples with water to separate the subsamples. Considering the loss of water content during crushing and sieving, the graded water loss rate T is introduced. Based on studying the characteristic of weathered granitic soil particle separation curve and assuming that the moisture content of coarse particles is proportional to the specific surface area and combined with the conventional sieving test data, a multi-unknown equation group is established to calculate the water content of each particle and the graded water loss rate T. The results of tests and data analysis show that there is a certain systematic error in this measurement method, which can lead to diversify the calculation results and even result in incorrect solutions. The multiple groups of sample parallel tests can effectively resolve the problem. Related Articles | Metrics

Select

Application of Acoustic Transmission and Low Strain Reflection Wave Methods in the Integrity Testing of Piles in Beijing New Airport LEI Yongyu, WU Xiaohan, ZOU Guigao 2020, 34 (1):  84-88.  Abstract ( 393 )   Save With the rapid development, there are more and more urban highrise building structures. As the major building foundation type, the piled foundation has strong adaptability, good seismic performance, high axial capacity and small settlement under the structure loadings, so it is particularly important to ensure the quality of bored and castinplace pile so that the foundation safety can be met. This paper presents a case history of the pile integrity testing methods used in the Beijing new airport terminal project. Both the acoustic transmission and the low strain reflection wave methods were used in the project and their advantages and disadvantages were compared. It is concluded that the combination application of both method on the same pile can improve the accuracy of testing results. Related Articles | Metrics