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20 August 2018, Volume 32 Issue 4 Previous Issue    Next Issue

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Analysis of the Open-Type TBM Excavation in Poor Geological Conditions in Pakistan N-J Hydropower Project ZENG Linglong， LEI Shangwen 2018, 32 (4):  365-368.  Abstract ( 756 )   Save The construction of the Pakistan NeelumJhelum (NJ) Hydropower Plant, which is in the northwest side of Himalaya Mountains, is primarily depend on the underground tunnel excavation in poor and complicated geological conditions and high overburden geopressures. Based on the construction of opentype TBM trail excavation at the headrace tunnel, the surrounding rock mass classification in opentype TBM tunnel was summarized, then the initial supporting parameters under the different surrounding rock mass conditions and technical measures of construction in the fracture zone have been determined. Related Articles | Metrics

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Review of Pile Foundation Applications in Dezhou Area YAO Lingyun1， ZHANG Shusheng2 2018, 32 (4):  369-372.  Abstract ( 571 )   Save The alluvial deposits from the Yellow River Delta are widely distributed in Urban Dezhou and its surrounding areas. With the construction of highrised buildings, the pile foundation and other soil improvement methods are widely applied in various projects. Due to the heterogeneous nature of the soils underneath the alluvial plain and the different construction skills among contractors, construction defects and accidents from the pile installations such as failing to reach the design axial capacity are frequently encountered. This paper discussed the pile types that are commonly used in Dezhou area and technical aspects of the pile installations. Related Articles | Metrics

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Dynamic Compaction Method in Improving of Sandy Gravel and Pebble Soils XIANG Rui1, WANG Peiqing1, WANG Qiang2， HU Yanjie1 2018, 32 (4):  373-375.  Abstract ( 767 )   Save The thick and loose sandy gravel and pebble soils are widely deposited in the river and valley region of southeast Tibet. The gravel and pebble soils have a high shear strength and good water stability, but they are difficult to compact. Based on the experience of various dynamic projects performed on the thick deposited gravel and pebble soils, it is concluded that the dynamic compaction method can improve the bearing capacity characteristics and meeting the project requirements. Dynamic compaction method is proved to be a wellestablished and costeffective method for various engineering projects. Related Articles | Metrics

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Application of the Prestressed Ground Anchors in Stabilization of High Cut Slopes LIAO Kunyang1， LIN Canyang2 2018, 32 (4):  376-378.  Abstract ( 672 )   Save The ground anchor is a technique that injecting the cementsand slurry in a small diameter borehole and grouting the ground anchor and surrounding soils so that the reaction can be provided throughout the grouted body. The prestressed ground anchor is a technique of providing a prestress at the top of the borehole in stabilizing the slope. This paper presents the principal aspects of the prestressed ground anchor design, construction and quality control as well as quality assurance. Related Articles | Metrics

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Application of Reinforced Flexible Structures in High Fill Embankments MENG Baohua1, DENG Yu2, ZHANG Ning2, WANG Ning3 2018, 32 (4):  379-384.  Abstract ( 587 )   Save This paper presents an application of reinforced flexible structure in a high fill embankment in Sichuan Province. The performance of the reinforced soil slope was analyzed by Lizhen commercial software and hand calculations. The results indicate that the slip surface of the unreinforced zone before adding the reinforcement can be used as the bases of determining the reinforcement length. Gabion basket treated slope reduces the potential settlement of the fill soils.  Related Articles | Metrics

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Applications of Foamed Concrete in Deep Soft Soils LIU Guoqing 2018, 32 (4):  385-388.  Abstract ( 649 )   Save As an innovative back fil material, the foamed concrete has the advantages having light weight and high flowability and workability. In recent years, it has received a wider application of constructing embankment over soft compressible soils as well as in back filling the bridge abutments. This paper presents a case history of a bridge abutment with the foamed concrete in the A6 Contract Section that consisting of deep soft soils in Xiapu, Fujian. The construction aspects of the foam concrete replacement embankment are discussed in the paper. The field monitoring results confirmed that the material can be applied to the deep soft foundation of the bridge abutments in terms of reducing the potential settlement. The results indicate that the construction schedule can be shortened with minimized and satisfactory embankment settlement. Related Articles | Metrics

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Stability Evaluation of a SoilRock Mixed Landslide in Guangxi WANG Jiabin, DENG Junjun 2018, 32 (4):  389-392.  Abstract ( 574 )   Save The geological and environmental conditions as well as the engineering geological characteristics of a soilrock mixed landslide in Guangxi are presented in this paper. The stability factors that affecting the landslide are analyzed based on the material composition and structure of the landslide. The factor of safety of the slope under its self weight and heavy rain conditions are analyzed by the limit equilibrium method. According to the analytical results and the deformation characteristics of the landslide, it is determined that the slope is in a stable state under the selfweight condition only and is in an unstable state under the heavy rain condition. Prediction of the deformation trend of landslide is based on the stability nature of the slope. The compositional engineering treatment measures of “water interception and drainage measures plus antislide pile engineering as well as the retaining wall with fieldmonitoring project” can effectively minimize further potential deformation of the slope as well as the geological hazards. Related Articles | Metrics

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Considerations on the Foundation Design in Hexi Soft Soils in Nanjing City LV Hengzhu1, LU Song2, DING Xin1 2018, 32 (4):  393-396.  Abstract ( 527 )   Save Based on the research results of the engineering characteristics of soft soils in Hexi area of Nanjing City, the geographical distribution and the engineering characteristics of the soil layers in the region have some common behaviors.Currently, most of projects are completed by the individual design teams and they only focused on the local geological conditions of the specific projects and foundation selection, the general engineering behavior of the foundation characteristics and the generic design of the aspects of the foundation structure in the region are seldomly summarized.In order to fully utilize the foundation bearing capacity and other geotechnical resources of the area,this paper provides a summary of soil properties of the soil in the region based on a large number of data and experience accumulated during the engineering practice. The foundation design and construction recommendations are provided in the paper, such as, methods of concrete pipe pile selection, construction of castinplace reinforced concrete piles, and considerations of the pile static load tests. Related Articles | Metrics

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An Introduction of the Wood Building Construction Technique SHI Lingyi 2018, 32 (4):  397-399.  Abstract ( 2687 )   Save The wood structure has the advantage of energy saving and other green features, therefore, receives wider applications in the United States, Canada, Europe, Australia, Japan and province of Taiwan, China. With the increasing awareness of environmental protection as well as the increasing concern of minimizing the earthquake hazards, the light weight wood structure can be used as an environmental friendly, good earth quake performance, and a sustainable development structure. This paper presents the construction techniques of single wood residential buildings in a development. Related Articles | Metrics

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A State of the Art Review of Research in Soil Color CHEN Ruyi1, LIU Guanshi2, ZENG Zhaotian1, ZENG Xianyun3 2018, 32 (4):  400-405.  Abstract ( 722 )   Save Soil color is a reflection to the basic properties of soils, which has great significance on the agricultural production, the climate analysis and the geotechnical engineering. In this paper, current researches on soil color description methods, color measurement methods and factors of influence on soil color are firstly introduced, then the shortage of researches on the relationship between soil color and its physical and mechanical properties is analyzed, finally, some advices are provided for further research such as the soil color acquisition, quantitative analysis of soil color and the influence factors, the relationship between soil color and physical and mechanical properties. Related Articles | Metrics

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Bearing Capacity and Deformation Characteristics of Grid Shaped Soil Cement Mixing Column Foundations YANG Junbo1, HU Shenggang2, FANG Ze2 2018, 32 (4):  406-410.  Abstract ( 910 )   Save The requirements for the bearing capacity and the deformation control of large and highraised buildings are usually higher, The traditional piled foundation usually are required to penetrate the soft soil layer and to transfer the load to hard soil layer with higher bearing capacity. Therefore, the treatment depth is deeper results in a high construction cost.  The grid shaped soilcement mixingcolumn foundation can provide lateral restraints on the shallow soil underneath the foundation and results in an increase in bearing capacity of the composite soils and rigidity of the foundation. The treatment depth can significantly be reduced. This paper presents the stress and deformation properties of the grid shaped soil cement mixing soil columns. The analysis of the bearing capacity and the settlement of the composite ground is also introduced. Related Articles | Metrics

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A Determination Procedure of Foundation and Pile Bearing Capacity Under Slope Conditions ZHAO Kexiao1, YU Fei2, CHEN Shanxiong2 2018, 32 (4):  411-414.  Abstract ( 724 )   Save Under sloped conditions, the methods of calculating the foundation and pile bearing capacity are different from the those in leveled ground and various methods from different researches for the determining the foundation and pile bearing capacity under sloped conditions are proposed.A new analytical approach for the soil bearing capacity and pile axial capacity under the sloped condition is proposed by using MATLAB software. Combined with numerical examples,the results illustrate the proposed calculation method in the program by using the interpolation method with the adjustment coefficients are relatively accurate and comparable with the historical data.The influence of the slope ratio on the bearing capacity is also presented: the bearing capacity and slope ratio was inversely correlated,with the slope ratio decreases,the capacity increases, and the degree of capacity increase is related to the slope ratio. Related Articles | Metrics

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Application of Entity Unit Element in the Deep Excavation Supporting Analysis Using FLAC3D QI Deyin1, YU Bei2 2018, 32 (4):  415-418.  Abstract ( 1103 )   Save This paper presents the application of entity unit element in the deep excavation supporting analysis using FLAC3D commercial software. The advantage of using this new element is that the adverse of the number of connection joints on the numerical analysis can be minimized and the strain stress conditions in the supporting structure are more reliable. Therefore, the supporting design can be more accurate. Related Articles | Metrics

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Three-Dimensional Numerical Analysis of the Ventilation Shaft of an River Crossing Tunnel in Saturated Sandy Layers WAN Beijing 2018, 32 (4):  419-423.  Abstract ( 539 )   Save The ventilation shaft for a river crossing tunnel had a large embedment depth and closed to the river water and levee system with complicated geological and hydrological conditions. Higher safety measures were required due to the penetration of the saturated sandy layers. A rectangular box frame structure with slab and beam system was utilized for the ventilation shaft. Due to the numerous required openings on the shaft body, the structure has a typical threedimensional structure type and could only be simulated by the threedimensional analysis. A numerical model was established for the ventilation shaft. Analyses were performed and it was concluded that the middle portion of the shaft had larger stress and the structure design was appropriately performed. Related Articles | Metrics

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Comparative Study on the Methods for the Uplift Capacity of Spread Footings in Sand ZENG Erxian1,YE Aimin1, CHEN Cheng2, LIU Guanshi2, FENG Heng1 2018, 32 (4):  424-427.  Abstract ( 781 )   Save Based on the existing measured data, the calculation precision of earth cone method and shear method for calculating the ultimate uplift capacity of the spread foundation in sand recommended in “Technical Code for Foundation Design of Overhead Transmission Line” (DL/T 52192014) was evaluated in this paper. It is shown that the values of critical depth defined in the two methods are too small. A correspondent improvement against the critical depth was therefore given based on the previous studies. The values of ultimate uplift capacity obtained from the modified earth cone method and the modified shear method were all greater than those of the uncorrected results. The calculated results agreed well with the measured results. In addition, from the point of the degree of coincidence and safety design, the modified earth cone method is preferable. Related Articles | Metrics

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Estimation of the Insitu Stress in Rock Mass in the Tunnel of N-J Hydropower Station Excavated with TBM WANG Wenqiao, HU Quanguang, NING Guangzhong 2018, 32 (4):  428-432.  Abstract ( 661 )   Save For The geological condition is very complex for the NJ hydropower station in Pakistan. The maximum overburden depth of the NJ TBM tunnel reaches 1900 m. Rock burst occurs frequently during tunnel excavation. Insitu stress is one of the most important factors that influence the tendency of rock burst. The shape and thickness of the core discing are analyzed to estimate the principal stress direction and magnitude of the insitu stress of the TBM tunnel. The analyzed results show that the axis of the borehole is almost parallel to one of the principal stress directions. If the gravity stress is one of the principal stress, TBM tunnel axis is the third principal stress direction. The relationship between the two principal stresses in the horizontal plane is obtained. For lateral stress coefficient between 0.8-1.5, the magnitude of the other stress is 80 MPa-110 MPa. During tunnel excavation, strong rock burst is likely to occur in regions around the arch bottom and vault. Related Articles | Metrics

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Influence of Quartz Sand Content on the Electric Conductivity in Calcareous Sand JIANG Hanghai1,2,3, CHEN Weijun1,3, YAO Ruidan1, ZHANG Chenyang 1,3, CUI Xiang3 2018, 32 (4):  433-436.  Abstract ( 1621 )   Save The salinity rich in soil in the sandy coral island and lack of the underground fresh water resources cannot provide a longterm and stable habitat for animals and vegetations. The rain infiltration is the most important conservation of the freshwater resources in these sandy coral islands. Soil conductivity is a parameter that reflecting the salinity,but for various reasons,the grey calcareous sand often mixed with quartz sand,this effects on the conductivity of calcareous sand is of concern to us.The mixed calcareous and quartz sand samples with different particle sizes and different gradations are prepared for the laboratory tests. The threeparameter sensor used in the soil testing was CS655 type and the data were recorded by CR1000 data acquisition system. The results indicate that, the mixed soil conductivityincreased with the increase of quartz sand content and the change trend was first decreased, then increased and then decreased again with the quartz content, in most cases. In the first time the low conductivity appeared at a quartz sand content of approximately 20%. Therefore, this quartz sand content of 20% can effectively reduce the conductivity of calcareous sandy soil. Related Articles | Metrics

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Evaluation of the Performance of Cement Based Grouting Materials GE Yanming1,2,3, LONG Wei1,2, SONG Huijuan1,2 2018, 32 (4):  437-439.  Abstract ( 837 )   Save The main role of grouting for waterproof plugging and filling reinforcement and the results are largely determined by the performance of the grouting slurry. The performance of the slurry under different watercement ratios, bentonite and admixture content were summarized by conducting comparative tests. The results indicate that the main factor affecting the performance of the slurry is watercement ratio. The bentonite reduces the fluidity of the slurry, and the strength of the stone is significantly reduced when the cement content is more than 8%. The effect of the water reducing additives on the fluidity is obvious. The increase of the water content of the slurry will lead the increase of the water content of the slurry and the decrease of the cementation rate. Related Articles | Metrics

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Comparison the Artificial and Natural Aging Tests of Woven Polypropylene WANG Wei, WANG Qi 2018, 32 (4):  440-444.  Abstract ( 484 )   Save The comparative study of the artificially accelerated aging and natural ambient aging tests were performed o four different woven polypropylene fabric samples. The following conclusions can be summarized: under the same area and weight, the ambient aging results shown no significant differences over geotextiles with different aging retardation additives. However, woven polypropylene with more aging retardation additives has longer resistant time in the artificially accelerated aging tests. The results also show that the mechanisms between the natural ambient aging and artificially accelerated aging are different. From the relationship between the artificially accelerated aging and natural ambient aging, the rates of artificial aging are different for woven polypropylene with different amount of aging retardation additives. Related Articles | Metrics

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Self-balance Load Test of Axial Capacity of JZGZ Piles in the Ningbo Metro Project XU Shengfeng1, CHEN Hongyu2， ZHANG Zhenglong1， ZHU Jianmin1 2018, 32 (4):  445-448.  Abstract ( 671 )   Save During the construction of Ningbo rail transit, a new type of pile foundation  JZGZ pile was adopted. When the borehole is drilled to the designed elevation, the base of the current segment is expanded and then the cement slurry is injected and mixed with the soil; finally, the prefabricated pile is installed with enlarged joints. The JZGZ pile combines the advantages of drilled pile, prefabricated pile and deepmixing column. Its bearing capacity can be improved remarkably. In this paper, the selfbalanced method is applied to the vertical bearing capacity testing of the two JZGZ piles. It is concluded that the selfbalanced method is suitable for the JZGZ pile static load test. The measured results indicate that the axial capacity of the test piles met the design requirements. The loadsettlement curves of the two piles are roughly liner, and it shows that the JZGZ pile has good axial capacity. Related Articles | Metrics

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Methods for the Determination of the Calcium Carbonate in Calcareous Sand LI Xiaogang1, ZHU Changqi2, ZHANG Poyu1 2018, 32 (4):  449-452.  Abstract ( 1061 )   Save Calcareous sand is a marine sediment with main component of calcium carbonate. The calcium carbonate content in calcareous sand is a major index that of mechanical properties that is different from those in the quartz sand. In accordance with the general accepted classification standards, when the calcium carbonate content in the calcareous sand is more than 50%, the mechanical properties of the calcareous sand will have significantly different. Therefore, it is important to accurately determine calcium carbonate content in order to accurately evaluate the engineering properties of calcareous soils. The calcareous soil samples were collected from in Sanya, Hainan Province. Four different test methods, namely, comparative gasometric method, EDTA titration, atomic analysis method and atomic absorption spectrometry, were performed to determine the calcium carbonate content in soil samples. The results indicate that test results are very different among all four different methods. Further analysis indicates that the EDTA titration method had the highest correlation with the Xray diffraction method. Comparisons among the test difficulty, cost, analysis speed and test precision and other factors, indicate that the EDTA titration method is more suitable for the determination of calcium carbonate content in calcareous soils. Related Articles | Metrics

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Evaluations for the Soil Nail and Ground Anchor Load Tests Defined in Code JGJ120 ZHANG Kaiwei1,2, ZHI Zhenghua1,2, ZHI Liyuan1 2018, 32 (4):  453-454.  Abstract ( 745 )   Save JGJ1202012 Edition updates the anchor rod test requirements of ground anchors and the soil nail test requirements are also included. There are differences existed in both versions of the requirements: in the new code, the ultimate test load in the acceptance test is determined by the safety requirement of the deep excavation, whereas, the old version did not have this. Further, the acceptance test location should be randomly selected but no requirements on the acceptance of the sample pool. This paper discusses the differences between old and new codes. Related Articles | Metrics

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Evaluation of Moisture Content on the Unconfined Compressive Strength of Soft Soils LIU Yang1, SUN Qian1,2, YAN Changhong1 2018, 32 (4):  455-460.  Abstract ( 636 )   Save The soil near the free face will experience the unloading stress in the excavation or tunneling, for which the soil mass will results in the lateral deformation, especially in soft soils. To study theadverse effect of soil deformation under the unconfined condition,a conventional consolidation test apparatus was modified to conduct the unconfined compression test for soft clays. A series of laboratory tests were conducted to investigate the characteristics of the unconfined compression of undisturbed samples as well as remodeling samples. The result shows that the samplespresentthe characteristics of attenuation creep under each loading stage. The strain rate under the unconfined condition is far greater than it under the unidirectional compression condition. Further, the water content and the axial stress have a great influence on the deformation of soft soil. The relationship between strain and water content and axial stress are obtained by statistically fitting test data.  Related Articles | Metrics