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20 June 2019, Volume 33 Issue 3 Previous Issue    Next Issue

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Impact of Large Deep Excavation on the Safety Hazards of Rail Transit JIANG Ying1, WU Shouxiang1, ZHANG Dehai1, HUANG Wei2 2019, 33 (3):  239-242.  Abstract ( 391 )   Save The large foundation excavation will likely induce adverse effect on the operation of the adjacent rail transit, which is sensitive to the vibration and deformation. The design of the supporting structure for the foundation excavations near the rail transit should consider the site-specific environments. In this paper, a case history of the deep excavation near a rail transit line in Wenzhou is presented. The supporting for the proposed excavation area near the transit line was designed by using reinforced concrete rakers and earth berm support. Further, zoned excavation and temporary supporting system. Other effective methods, such as, reduce the time for the unsupported excavated area, ground improvement at the passive earth pressure zone at the bottom of excavation and minimize the soil erosion, could also considered. The paper also presents a numerical study results of foundation excavation effect on the transit bridge abutment of Line S1 and other adjacent train station structures.  Related Articles | Metrics

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Design and Construction of Double Row SMW Method Piles in Deep Excavations in Thick Silt and Fine Sand Strata ZHANG Yinong 2019, 33 (3):  243-245.  Abstract ( 410 )   Save The soil-cement mixed wall inserted with medium sized hot rolled steel beams has received more and more applications as the deep excavation supporting structures. Since the rare pile will resist the uplift load, the reinforced soil cement mixed wall has not been widely used as the supporting structure without horizontal bracing. This paper presents the application of double row piles with soil cement mixed wall without ground anchor or other horizontal supporting structure for a deep excavation project in Shunde District of Foshan City. The thick silt and fine sand soils are predominant at the project site. Both design principles and construction methods are introduced in the paper. The twodimensional finite element software PLAXIS was used to analysis the typical supporting section. The construction monitored data were also compared with the numerical analysis results. It is concluded that the double row piles with soil cement mixed soil wall could be used as a supporting structure in the deep excavation in thick silt and fine sand layer. Related Articles | Metrics

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Application of Grouting Combined with the Steel Pipe Pile Method in Poor Soils in Karst WANG Junsong 2019, 33 (3):  246-249.  Abstract ( 277 )   Save Even during the final design stage, the complete distribution of the karst cavities under the proposed site is not possible. Usually, the rock pinnacles are well developed in these areas and a large amount of saturated loose sand with mud and abundant groundwater are existed in soil and rock interface. During the foundation excavation for the shallow foundation on natural soils, the poor and saturated soils are very difficult to be removed and the potential safety hazards are existed due to the underlying karstic cavities. The grouting method is a conventional ground improvement method for the karst soil treatment. However, due to the well-developed rock fissures, the result of the grouting is very difficult to predict, and the rock fissures cannot be completely filled. Therefore, the pipe piles can be applied to carry portion of vertical loads. This paper presents a high-raised residential building ground improvement case history of applying the grouting method and the pipe piles. The monitoring results indicate that no differential settlement was occurred and the cracks on the basement wall had no further development. Related Articles | Metrics

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Application of Thin-Walled Large Diameter Reinforced Concrete Cylindrical Pile as  Deep Excavation Cantilever Supporting Structure in Soft Soils WANG Huanxin1, LI Qilin2, TENG Hui3, WANG Jun1 2019, 33 (3):  250-254.  Abstract ( 246 )   Save Selection of a cost effective and safe supporting structure for the deep excavation in soft soils with relatively shallow depth is critical to the foundation cost control. The supporting structure selections of sallow excavation depth in Whenzhou soft soils are evaluated through a case history from aspects of design approach, analysis method, and construction monitoring. The following conclusions can be presented: ⑴Thinwalled cantilever large diameter reinforced concrete cylindrical pile has the advantages of cost effective, short construction period, and good deformation control in the constraint space where the slope, or ground anchor cannot be applied. ⑵It is inappropriate to estimate the total deflection only from formula in the code and the total deflection should consider the daily creep. Further, the allowable total deflection should consider the adjacent environment. ⑶The deeper excavation such as the excavation of elevator shaft, has the obvious adverse effect of the safety of supporting structure. The supporting design of these areas should be specially considered. Related Articles | Metrics

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Auger Cast Pile Installation in Gravelly Soils with Boulders FAN Junrang1, LI Hui1, LI Yi2 2019, 33 (3):  255-257.  Abstract ( 580 )   Save The techniques that can penetrate the gravelly soil with large size boulders and maintain the stabilities of bore holes are key factors for the success of the castinplace reinforced concrete pile installation. This paper presents a new allflight auger drilling method with special drill bit and a shallow displacement auger. With the secondary drilling, the majority of the boulder and large size gravel soils can be pushed into the adjacent soils so that the displacement type of the cast-in-place reinforced concrete piles can be successfully formed. The concrete pile integrity and static loading test indicated that the concrete pile installed with the new method had good installation quality. Due to the compaction effect, higher axial pile capacity can be obtained. Related Articles | Metrics

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Application of Point Well Dewatering and Dynamic Compaction Methods in the Treatment of Tailing Sand ZHAO Xiaofei1, CHEN Huilin1， QI Deyin2 2019, 33 (3):  258-260.  Abstract ( 325 )   Save Tailing sand consists of fine sand and other finegrained material from the mining wastes. The tailing sand discharged in to the tailing reservoir in the form of slurry and the engineering properties of this solid deposit have the characteristics of high moisture content, high void ratio. A new soil improvement method, which is the combination of pointwell dewatering and dynamic compaction, is introduced in this paper. This method has the advantages of short construction period and cost effective. This paper presents the soil improvement results of tailing sands in Dahongshan tailing reservoir. The site in-situ tests and monitoring results indicated that this is a very effective soil improvement method for the tailing sand materials. The project won the national first-grade award in the geotechnical investigation QC group. Related Articles | Metrics

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Influence of Pipe Jacking on the Adjacent Tram Lines CAO Yilong 2019, 33 (3):  261-263.  Abstract ( 286 )   Save The construction of a pipe jacking project that adjacent to the existing Tram Line No. 1 in Suzhou under operation was numerically simulated. The launching jacking pit excavation and the pipe jacking process were simulated by using the modified MohrCoulomb constitutive model. The construction sequence was therefore optimized from the numerical analysis results. From the numerical analysis results of the pipe jacking, it is concluded that both the maximum vertical and lateral movement at the existing tram line met the code allowable values.  Related Articles | Metrics

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Rock Mass Stability Monitoring and Supporting Optimization of Highway Tunnel Excavation or Expansion QIU Liqiu 2019, 33 (3):  264-267.  Abstract ( 307 )   Save The real time monitoring program on the rock mass was implemented in the Houci Tunnel excavation of Zhanglong Expressway in Fujian Province. The objective of the instrumentation program was to monitor the deformations at crest and walls at both sides of the excavated tunnel. The threedimensional finite element analysis model was established to simulate the rock mass deformations before and after tunnel excavation. Further, both the length and the spacing of the ground anchor were optimized from the numerical analysis and the results can be applied for the support of the tunnel excavations. Related Articles | Metrics

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Influence of the Earthwork on the Stability of Deep Excavation Supporting System CHEN Hongzhi1,2, JIAN Wenbin1,2， WANG Zhenfeng3 2019, 33 (3):  268-271.  Abstract ( 516 )   Save Geotechnical engineering and earthworks have their own complexity and characteristics. Earthwork is an integral part of earth work engineering which has a significant influence on deep excavation supporting system. For the purpose of evaluating the influence of earthwork sequence on the excavation projects, a case history is presented in this paper. Three aspects, which are earthwork sequence on the supporting structure construction, production pile installation, and stability of the supporting structure, are evaluated. The results indicate that the earthwork sequence has a significant impact of the stability of the excavated area and should be carefully designed. The monitoring results demonstrated that actual excavation sequence was appropriate. Suggestions on the excavation projects are also provided in the paper. Related Articles | Metrics

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Retractable Strut Installations During the Backfill of Subway Station Excavations HUANG Zhenbo 2019, 33 (3):  272-275.  Abstract ( 501 )   Save During the backfilling of the underground structures for a subway station, if a cross strut needs to be removed, an extractable strut is usually installed below this cross strut. Conventionally, the extractable strut is not optimized for the deformation control. This paper presents a case history of the application of the extractable strut in the supporting of Xingtang Street Station structures for Suzhou Transit Line No.5. The locations of the vertical struts were evaluated. Several different struts plus extractable struts were compared. It is concluded that different strut arrangement resulted in different maximum bending moment and at different locations. For the backfilling of the subway station, the number of extractable struts should be minimized and even avoid as long as the maximum bending moment is within the tolerable limits. Although the reduction of the extractable will result in the increase of the bending moments in the supporting structures and increase the content of steel, the over construction cost is still cost effective. Related Articles | Metrics

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Impact of the Underpass Construction on the Underlying Subway Tunnel Structure KONG Juan 2019, 33 (3):  276-279.  Abstract ( 375 )   Save The foundation excavation above the tunnel structures will change the stress field due to the unloading of soils and disturb the adjacent soils surround the excavated area. Therefore, the tunnel structure might be adversely affected by the construction above. This paper proposes the optimized deep excavation method and sequences that can ensure the safety of the tunnel structure as well as the operation safety. Both the analysis and construction monitoring results indicate that the appropriate soil improvement at the bottom, utilizing the uplift piles, slabs that can resist the buoyancy, appropriate layered and zone excavation are the effective ways to control the deformation of the underlying tunnel. During the excavation, it is also important to select the construction method that having minimal impact to the adjacent environment and to utilize the informational construction methods that providing realtime feed back to the proposed construction. Related Articles | Metrics

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Influence of a New Metro Line Construction at the Exchange Station on the Existing Subways SONG Leipeng 2019, 33 (3):  280-284.  Abstract ( 449 )   Save As an important node in urban rail transit network, the exchange station connects different major metro lines, which offers a very convenience experience for the commute passengers. There are two construction methods of an exchange station: one stage construction and phased construction. For a phased construction exchange station, the excavation of the station foundation structure will have an impact of the existing station and rail tracks. A three-dimension finite element model was established to analysis the new station construction on the existing station and rail tracks. Based on the numerical results, the supporting structure design was optimized, and the potential construction hazards and their remediation methods are also discussed in this paper. Related Articles | Metrics

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Design and Analysis of a Municipal Tunnel Intersecting with a Rail Transit Tunnel HE Zhenhua 2019, 33 (3):  285-289.  Abstract ( 368 )   Save The construction of a municipal tunnel that intersecting with a rail transit tunnel might adversely affect the structural integrity of the transit tunnel. An effective method to reduce the safety hazards of the transit tunnel is to appropriately determine the construction sequences of the tunnels. This paper presents the case history of the construction of Chengdu Metro No. 4 Line tunnel which was intersect the municipal tunnel under the Wenquan Boulevard. The consequence was to excavate the transit tunnel using the shielded method and the open cut construction method to install the municipal tunnel above. During the construction of upper protective isolation layer of the transit tunnel, the bottom slab of the municipal tunnel and the uplift piles, the posttensioned ground anchors were installed in between the uplift piles. The transit tunnel could be shielded tunneling can be excavated after the adjacent soil mass was stabled. The prestresses could then be released progressively. During this period, the tunnel frame structures and the underground space structures could be installed. The finite element analysis conclude that this design scheme was appropriate. The prestress in the uplift piles could effectively reduce the structure safety hazards within the shielded zone. Related Articles | Metrics

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Application of BIM Technology in Tunnel Segments TANG Yanmei, ZHANG Chenchen, WANG Xinlong 2019, 33 (3):  290-294.  Abstract ( 363 )   Save At present shield tunneling method is applied more and more in underground tunnel construction. The standard ring and turning ring should be assembled to meet the design axis of curved section tunnel. The curve is composed of a circle curve and two relief curves, and the layout plan of the pipe sheet is determined by theoretical calculation of the turning Angle of the design axis and the deflection Angle of the pipe sheet in the turning circle. The 3D model of shield tunnel was established through BIM technology, and the theoretical layout was optimized. In addition, the assembly quality of tunnel segments in the construction process was simulated and the onsite construction of pipe segments was guided, so that the formed tunnel axis could better echo the designed axis and ensure the tunnel construction quality. Related Articles | Metrics

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Influencing Factors for Particle Breakage of the Calcareous Sand under Triaxial Tests WENG Yiling1, YIN Juan1, CHEN Weijun1, YU Kefu2, WANG Xinzhi3 2019, 33 (3):  295-298.  Abstract ( 442 )   Save Extensive triaxial tests were performed on calcareous sand samples from coral reefs in South China Sea to study the properties of particle breakage. Factors that might affect the particle breakage, such as, confining pressure, sample grain size, sample gradation, degree of compaction, drainage condition and initial sample moisture content, were studied. The following conclusions can be obtained: the particle breakage of the calcareous samples is related to the magnitude of confining pressure and does not have relationship with the sample grain size. Well graded samples have less amount of particle breakage; higher degree of compaction increases the amount of particle breakage; under different drainage conditions in the triaxial tests, the effective confining pressure has a large influence; the particle breakage increases with the initial moisture content of samples. Related Articles | Metrics

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Developments of Characterization of the Shrinkage Properties of Expansive Soils MU Zhi1, LIU Guanshi2, CHEN Ruyi1, MO Yankun1， SHENG Luanxiang3 2019, 33 (3):  299-304.  Abstract ( 377 )   Save The volume shrinkage of expansive soils will occur after water loss, which will ultimately lead to cracks. Due to which it has an important impact on its Mechanical and Engineering properties. Therefore the research on expansive soils shrinkage has been paid much attention and made many progress. In this paper, the basic characteristics, main influencing factors, shrinkage mechanism and shrinkage model of expansive soil are introduced along with existing problems and shortcomings are briefly analyzed. It is concluded that the study on shrinkage characteristics of expansive soils should be deepened from the following aspects: the relationship between mineral composition and content; shrinkage characteristics of expansive soils; the relationship between crystal structure and shrinkage mechanism of expansive clay minerals; and the influence of structure on shrinkage characteristics of expansive soils. Related Articles | Metrics

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A Prediction Method Using GA-BP Neural Network for the Frictional Resistance of PHC Piles ZHANG Jie1, SHI Li2 2019, 33 (3):  304-307.  Abstract ( 322 )   Save This paper presents a new method, which is called GABP method, that can effectively predict the axial resistance of prestressed highintensity concrete (PHC) piles. Various soil properties, such as, index properties, mechanical properties, on the axial capacity of PHC piles are evaluated and factors that have largest influence on the pile capacity are determined. This new method, which combines the genetic algorithm (GA) method and artificial neural network back propagation (BP) method, applies the statistical method of multi factors in GABP neural network system in the axial capacity predictions of PHC pile in cohesive and noncohesive soil in Shanghai. The results indicated that this method is successful. Related Articles | Metrics

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The Effect of Deformation at the Crest of Ribbed Double Arch Tunnel on Its Structural Stability YI Yuelin1, FANG Tao1, YU Fei2, CHEN Shanxiong2, CHU Xiaojie2 2019, 33 (3):  308-312.  Abstract ( 338 )   Save Construction monitoring plan for the ribbed double arch tunnel excavation was established based on its structural and stress-strain characteristics. The major risk in the tunnel excavation, which is the cracking at the crest of the tunnel, was evaluated based on the construction monitoring data. The lining structure, ribbed strengthening, and the midwall were evaluated based on the monitoring results and mitigation measures were implemented accordingly to ensure the safe excavation and operation of the tunnel. Related Articles | Metrics

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Discussions on the Some Clauses in Standards for the Geotechnical Investigation of Tall Buildings JGJ/T120-2017 FANG Yuming 2019, 33 (3):  313-319.  Abstract ( 1326 )   Save Standards for the Geotechnical Investigations of Tall Buildings (JGJ/T120-2017) was effective since February 1, 2018. In the process of applying the standards in the practical engineering projects, it is found that some of the clauses might be ambiguous or might have "error". To understand the intention of the standards, some aspects are discussed in this paper. These aspects are: first, whether terminologies defined in the standard are reasonable or not; second, whether terminologies used in this standard have clear and unique definition in the geotechnical engineering; third, whether the content of the clauses in the standard are reasonable; fourth, whether the clauses in the standard are clearly and well presented; fifth, whether a requirement in different clauses is consistent; and last, whether a requirement in the standard is consistent with the referenced standards. Based on the analysis, it is concluded that some of the clauses have at least one of the issues mentioned above. Improvement suggestions have also proposed in the paper to help further understanding and application of this new standard. Related Articles | Metrics

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Considerations on the Laboratory Testing Standards-Using Triaxial Shear Test and  One-Dimensional Consolidation Test at High Pressure LI Shu1, FENG Hongchao1， ZHANG Lizhan2 2019, 33 (3):  320-325.  Abstract ( 430 )   Save Laboratory test standards are widely using the geotechnical investigation for various engineering projects. However, some of the standard procedures need to be modified for soils under special conditions so that the tested parameters are reasonable. As examples, it is observed that, in the drained and consolidated triaxial (CD) test, the quantity of drainage from the different water weight is greater than the theoretical drainage quantity, this will result in the increase the testing error since a larger actual major effective stress at failure. It is suggested that, in the CD test, the consolidated drainage be calculated as the loss of soil mass subtracts the drainage during the shearing. The preconsolidation pressure of cohesive soils can be obtained from the onedimensional consolidation test to the enough high consolidation pressure. To obtain an accurate preconsolidation pressure of soil samples, higher consolidation pressure is required for stiff soil or soil sample from a great depth. Before applying the Casagrande method, the soil deformation at preconsolidation pressures greater than 3200 kPa can be estimated from the previous testing pressures. These modifications provide efficient ways of test soil properties. Related Articles | Metrics

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Review of the Applications of Shredded Tire Chips for the Soil Reinforcements DU Zhenjiang 2019, 33 (3):  326-330.  Abstract ( 489 )   Save Both theoretical and practical progresses aspects of the application of recycled tires in the geotechnical engineering have been achieved in recent years. This paper presents a state of the art review of the application of shredded waste tire chips in the strengthening of various soils, such as, sandy soils, expansive soils; collapsible loess and cohesive soils. The results and effects of various mixing contents and tire chips sizes in these soils are reviewed. The results indicate that, larger tire chip size can improve the frictional resistance at the face of shearing and therefore increase the strength of mixed soils. The tire chips mixed soils can reduce the unit weight in the geotechnical and roadway engineering and can improved both strength and stiffness of soils. It is suggested that the cyclic shear resistance, aging effect of tire chips and impact of tie chips to the adjacent environment need to be further investigated. Related Articles | Metrics

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Identification of Unloading Zone of Rock Mass for Bridge Abutments from Undisturbed Rock Core Samples in Deeply Cut River Valley WEN Hai1, ZHANG Yongguang2, SUO Peisi3 2019, 33 (3):  331-334.  Abstract ( 361 )   Save The unloading zones in the rock mass are frequently encountered in the deeply cut river valleys. The geological properties and limits of these unloading zones might determine the locations the proposed bridge abutments. The conventional exploration drift method has the disadvantage of time consuming, high cost and poor safety. However, a new exploration method, which utilizes a semiclosed single action double tube rock core bit to extract the undisturbed rock cores, can provide a rapid, cost effective and safe method to investigate the river banks. This method can efficiently analysis the structure plane, perform statistical analysis on rock core RQDs and provide qualitative and semi quantitative evaluation results for the unloading zones at both sides of the river banks. This paper presents the exploration results for the proposed Jiangdi River Bridge in Yongren to Dayao Highway Project. In this project, the semiclosed, single action and double tube rock core bit and undisturbed rock core preservation technique were first used in the evaluation of the unlading geologic zone. Related Articles | Metrics

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Estimation of Earth Pressures Behind a Soldier Pile and Lagging with Inclinedly Inserted Panel Wall Considering the Soil Arching Effect DUAN Zixia1，　QU Juntong2，　ZI Xiaolei2，　LEI Zhen2，　QU Linhe3 2019, 33 (3):  335-338.  Abstract ( 404 )   Save The soldier pile and lagging with inclinedly inserted panel wall has a special configuration since the soil behind the wall can deform freely and the drainage path behind the wall is connected to the ambient environment. Therefore, the earth pressure distribution, magnitude and the soil arching behind the retaining wall are affected by its unique configuration. This paper presents the earth pressure estimation formula for the soldier pile and lagging with inclinedly inserted panel wall considering the soil arching effect. The earth pressures obtained by the recommended formula, physical model tests, and numerical analysis results by AQAQUS finite element analysis method are compared. It is concluded that the proposed formula can fairly estimate the earth pressure on this new retaining structure type. Related Articles | Metrics

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Numerical Analysis on the Deformation Characteristics of a Deep Excavation HU Desheng， LIU Bin 2019, 33 (3):  339-342.  Abstract ( 430 )   Save Numerical analyses using MIDAS GTS for a sloped deep excavation using two layers of inclined supporting (rakers) system were performed to evaluate the deformation characteristics of a deep excavation under complexed subsurface soil conditions in Xuzhou. The construction monitoring locations were optimized based on the numerical analysis results and monitoring data were compared with the analytical results. The results indicate that, after applying the first layer of rakers, both vertical and horizontal deformations were observed at the bottom of the excavation and larger horizontal deformation was monitored. After the installation of the second layer of rakers, both vertical and horizontal deformation increased, and they were within the tolerable zone. When the excavation reached at the final proposed depth, the predicted and monitored horizontal deflections stabilized. Related Articles | Metrics

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Application of Exponential Function Model in the Settlement Prediction of Pile Supported Bridge Foundations LI Hongtao, LIU Sijia, HU Tongxu, WANG Wen 2019, 33 (3):  343-346.  Abstract ( 367 )   Save An exponential function is induced to predict the piled supported bridge pier settlement during the construction of high-speed rail lines. This paper briefly introduces the characteristics of this exponential function and method to determine its parameters. This paper also presents a case history of the new construction of Congli railway bridge. Different models were used to predict the piled foundation settlement: index function model, Logistic function model as well as exponential function model. The results indicate that the exponential function have a better prediction of the foundation settlement. Related Articles | Metrics

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Study on the Sedimentation of Aluminum Sludge from Pingguo Mine Under the Electric Field Action HU Yuefa1,2, SUN Gangchen1,2, GONG Zilong1,2, YAN Hangyu3 2019, 33 (3):  347-350.  Abstract ( 375 )   Save Bauxite tailing sludge is a high moisture content slurry formed in the process of alumina production, which has the characteristics of fine particle size, large specific surface area, high water content and difficult to settle in the suspension liquid. In order to further study the sedimentation mechanism of bauxite slurry under the applied electric field, the sedimentation tests of the sludge under different direct electric field (0V, 9V, 12V, 24V, 36V) were conducted. During the sediment of the aluminum sludge, the clear liquid height, transient and average sediment velocity of the particles were real-time monitored. The electrophoretic phenomenon in the aluminum sludge was also observed and its effect on the sedimentation of the mine sludge were also discussed. The results show that the sedimentation effect of the mud is enhanced with the increase of the electric field magnitude. Because of the negative charge of the mud particles, as the electric field magnitude increases, the particles of the mud will accelerate the movement of the anode to the metal electrode plate. Under a given DC voltage condition (0V, 9V, 12V, 24V, 36V), the voltage of 36V should be the threshold voltage and 48V is the "upper limit voltage" for the applied electric field. Related Articles | Metrics

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Engineering Geological Characteristics of Granitic Residual Soils in a Highway Project in Southwest Yunnan YANG Zhigang 2019, 33 (3):  351-354.  Abstract ( 418 )   Save Granitic residual soils are widely distributed in Yunnan Province and their engineering geology properties have a great influence on the engineering properties due to their unique geological characteristics. This paper presents the physical and mechanical properties of the granitic residual soils in a highway project in the southwest Yunnan Province. The feasibility of using this material was evaluated from many aspects, such as, coarse grain content, optimum moisture content, CBR values and in-situ dynamic cone penetration tests. Suggestions and recommendations of using this material has also presented in this paper. Related Articles | Metrics

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Meso-structure and Mechanical Properties of Basalt Aggregates as Roadway Surface Course Material WANG Pengpeng1， ZHANG Bo2 2019, 33 (3):  355-358.  Abstract ( 744 )   Save Due to its good mechanical properties, basalt is widely used as a good coarse aggregate in the highway construction. The Emeishan formation basalt samples in Bijie area were tested and three different types of basalt can be categorized based on their mineral composition and mesostructure properties. The values for crushing, abrasion and polishing were laboratory tested. The test results indicated that, due to the effect of mineral composition and mesostructures, these representative values might vary significantly. Higher abrasion values were obtained from angulartype and almond type basalt samples. The fresh or slightly weathered pulled basalt with interlocked structures can be used as aggregates for the surface course for the pavements in expressway and firstclass highway in wet weather areas. Related Articles | Metrics

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Seepage and Stability Analyses of a Landslide in Colluvium under Precipitations YU Xing1, LIU Linjie2 2019, 33 (3):  359-362.  Abstract ( 384 )   Save A landslide in Weining County of Bijie City was studied with SEEP software based on the saturatedunsaturated seepage theory in soils. The factor of safety in the stability analysis was obtained with various seepage time, pore water pressure at various locations in the slope. The results indicated that, during and after an extended precipitation, the factor of safety for the slope stability decrease first and then increase. The lowest factor of safety for the surficial slide model is at the end of the rainfall and the factor of safety for the deepseated slope stability occurred at time after the precipitation event. Related Articles | Metrics

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Stability Analysis of the Reactivation of an Existing Landslide MAO Feng1, ZHANG Guitao2 2019, 33 (3):  363-365.  Abstract ( 423 )   Save Factors that might trigger the reactivation of an existing landslide in mountain areas were examined and the factor of safety was obtained by using transferring coefficient method. The results indicate two categories of factors, which are internal factors and external factors, could attribute to the landslide reactivation. Mainly, under the unfavorable geological conditions, the landslide reactivation can be triggered by human activities and precipitations. Especially, the rainfall has the highest probability to trigger the landslide. Therefore, drainage facilities should be considered and installed in the landslide area. Related Articles | Metrics

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Application for the Gray System Prediction Theory in the Static Pile Lading Tests WANG Fengmei1, CHEN Zhidong1, ZHANG Lingshuai1, HAN Xiaofeng1, LU Zhao1,2,3, CHEN Rui3 2019, 33 (3):  366-369.  Abstract ( 413 )   Save The ultimate axial capacity of pile is an important parameter for the design and construction of pile supported foundations, however, it is difficult to statically load the pile to failure. As a new prediction method, the gray system theory can accurately predict the ultimate axial load at pile failure and needs fewer data points. This paper presents a gray system prediction model based on the deflections of pile head under different loadings in the pile axial static load tests and its application in the ultimate load prediction for other pile axial load tests. The following conclusions can be made: Although some errors might exist, the predicted pile head deflection using the gray system model are generally consistent with the static load test results on piles with various lengths. It is also concluded that the gray system theory has a good result in predicting the ultimate pile capacity of piles. Related Articles | Metrics

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Fast Testing Methods and Numerical Analysis on the Integrity of a Levee Cut-off Wall WANG Yuanming1, YAO Hailin2, CHE Ailan3, LI Heng1,4, LUO Xingwen2， LU Zheng2 2019, 33 (3):  370-374.  Abstract ( 499 )   Save Both quality and safety of levee cutoff walls are very important for the nation's economics and people's daily activities, therefore, effective and fast testing methods of the integrity of these levee cutoff walls are necessary. The elastic wave imaging method is a nondestructive testing method based on the elastic wave reflection principles and it has the advantages of high efficiency and direct testing results. Based on the elastic wave propagation in the levee theory, this paper presents the numerical analysis results for different types of defects that are commonly encountered in the construction, such as, vertical throughout joints, cutoff wall that does not reach its design depth, and voids in the concrete. The relationships between the response energy and the defects in the levee cutoff wall are established. It is possible to provide a fast defect testing method for the integrity of the levee cutoff walls. Related Articles | Metrics

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Evaluation and Testing of Freeze-Thaw Induced Subgrade Damage Under the High-Speed Rail Tunnel LI Wei1， TANG Hua2 2019, 33 (3):  375-378.  Abstract ( 293 )   Save China's high-speed railway is at the critical period of the constructing of new alignments and maintenance the existing lines. The operation and maintenance of railway are of great significance. Some of the induced hazards, which might affect the safe operation of the high-speed rail lines, have been observed at the high-speed rail tunnels, especially, the seasonal freeze-thaw related hazards in the frozen soil areas. These hazards included cracks at the tunnel lining structures, spalling of concrete, seepage at tunnel crests and separation of tunnel structure and adjacent geomaterials, etc. This paper presents a hazard investigation of a tunnel near Longjia Airport at Changchun-Jilin Inter City High-Speed Rail Line. Reasons that resulting these hazards and in-situ testing and evaluation methods are discussed in the paper. The results indicate that, the ponded groundwater was accumulated underneath the mat foundation at different locations and it is possible these isolated water accumulation areas might inter-connected. The test results were consistent with the visual inspections. Related Articles | Metrics

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State of the Practice Review of the Estimating of the Thickness of Loose Sediment at the Bottom of Drilled Piles LIU Ke1, HOU Longqing1, LI Mingdong1,2,3, DAI Renhui1 2019, 33 (3):  379-383.  Abstract ( 571 )   Save The loose sediment at the bottom of bored piles will reduce the side friction and the resistance at the bottom of the pile. It is one of the important factors affecting the quality of the bored pile foundation. Due to the adverse effect of the bottom loose sediment to the bearing resistance of bored piles, the accurate measurement of the thickness of the bottom loose sediments is an important aspect in the bored pile construction. The soft sediment measurement methods before and after the concrete pouring for different construction procedures are summarized in this paper. The principles and results of these measurement methods are also introduced. Different methods for the specific construction methods are also recommended in this paper. Related Articles | Metrics

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Experimental Study on Dynamic Parameters of the Silty Clay Surrounding a Metro Tunnel ZHAO Zhonghua1, LEI Yong2， LU Fatan3 2019, 33 (3):  384-388.  Abstract ( 509 )   Save The dynamic parameters (dynamic shear modulus and damping ratio) of a silty clay surrounding the metro tunnel were studied by using the GDS resonant column test and the dynamic shear modulus and damping ratio of the silty clay samples were analyzed under different confining pressures. The results show that, with the increase of dynamic shear strain, the dynamic shear modulus decreases and the damping ratio increases; with the increase of confining pressure, the dynamic shear modulus increases and the damping ratio decreases and the effect of confining pressures on the dynamic shear modulus is more significant than that of the damping ratio; the liquid index has smaller effect, the effect of the confining pressure on the damping ratio is more obvious; the relationships between the maximum dynamic shear modulus and the confining pressure, the reference shear strain and the confining pressure, the maximum damping ratio and confining pressure has a good linear relationship. Related Articles | Metrics

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Factors Affecting the Laboratory Compaction Test Results WEI Ying 2019, 33 (3):  389-392.  Abstract ( 1258 )   Save There are many factors affecting the results of laboratory compaction test, such as, sample preparation methods, compaction standard applied, compactive energy applied, soil moisture contents, height of residual soil in the container, particle size distribution, organic content in the sample, etc. The influence of soil types, moisture content, particle size distribution and organic matter on the test results is evaluated in this paper. The influence factors in the test procedures, such as sample preparation methods, compactive energy, residual soil height in the container and repetitive use of soil samples, are also analyzed in detail. The following conclusions could be drawn based on the evaluation results: Oven dried soils are recommended in the compaction tests. The height of residual soil should be strictly limited within 6 mm. The particle size distribution is an important factor. Through the analysis and discussion of these factors, the soil compaction results can be improved. Related Articles | Metrics