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20 February 2017, Volume 31 Issue 1 Previous Issue    Next Issue

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Side Friction of a Deep Caisson in Soft Soils under Service Loads PENG Jun1, LV Qigang2, TU Qing2 2017, 31 (1):  1-03.  Abstract ( 1026 )   Save This paper presents the analytical results of the side friction of a deep caisson in Zhuhai soft soils under the service load conditions. The segmental side friction estimation method was proposed based on the characteristics of the side friction distributions. The buoyancy design approaches can be divided into three different methods: No uplift approach; additional dead weight approach and side friction approach. Among these methods, side friction approach is the most effective one. The project practice indicates that the side friction model proposed in this paper can effectively reduce the side and bottom thickness of the caisson, as well as the additional dead weight. Related Articles | Metrics

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A Case History of Ground Deformation Induced by the Large Diameter Pipe Jacking Underneath a Maglev Line ZHANG Chi 2017, 31 (1):  4-07.  Abstract ( 1047 )   Save The engineering construction activities within the protective zone of the Maglev Rail Lines are increasing recently. The excessive deformation in the Maglev facility might adversely affect the safe operation of the Maglev Lines. This paper presents a case history of the ground deformation monitoring results of a jacked large diameter concrete DN4000 pipe underneath a pier supporting the Maglev Line. Before the pipe jacking installation, the soil at both sides of the proposed pipe and adjacent to the pier was improved by the compaction grout. Further, due to the deep embedment of the pipe and the relative shallow embedment of the pier foundation, the impact of the pipe jacking has minimal impact on the performance of the maglev lines. No grouting effort was made for the electrical cable trenches that are exposed in the ground surface. After the pipe jacking, it is observed that the cable trench had a rapid settlement and the settlement did not approach stable for a long time. It is concluded that the controllable deformation of the pier elevated structure is critical to the maglev line operation safety and the unimproved cable tranches are strongly affected by the pipe jacking construction. Related Articles | Metrics

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Application and Analysis of a Combined Unclosed Rake System for Shallow Foundation Excavation in Soft Soils SHAO Dongliang1, WANG Long1, SHI Xilin2, LI Zhi1 2017, 31 (1):  8-13.  Abstract ( 966 )   Save In the selection of the suitable supporting systems for the deep excavation supporting for the excavation depth less than seven meters, several rake systems are available. They are: reinforced concrete rakes; steel pipe rakes; rolled steel rakes; or the unclosed raking system from combination of above methods. This paper presents a case history of utilizing an unclosed rake system that from the combination of supporting methods used in various excavation areas in a deep excavation in Shanghai soft soils. Following an introduction of the overall project excavation support information, the application of various rakes, such as, reinforced concrete, steel pipe and rolled steel, as well as their critical design aspects are presented. The vertical face of the excavation could be gravity wall consisting of soilcement mixed columns, soilcement mixed wall (SMW). The paper also presents the predicted deformation in the supporting system using numerical analysis by PLAXIS. The predicted deformation results are comparable to the monitored data. Related Articles | Metrics

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Applications of Various Construction Joints in the Slurry Wall Construction WU Xinghong1, WU Weihong2 2017, 31 (1):  14-15.  Abstract ( 980 )   Save Having the advantages of high efficiency; short construction period and high reliability, the slurry wall is widely used in the deep excavation support, basement for building structures, underground shopping centers, parking lots, oil storage facilities, deeply embedded foundation for the highraised buildings as well as supporting structures for the topdown constructions. Various types of construction joints have been developed to meet the different requirements in the wider and wider applications. This paper presents the applications of various construction joints under different subsurface conditions and construction methods. It is concluded that various construction joints can have significant impact on the integrity, deformation and seepage performance of the slurry walls. They have further affect the construction cost. Related Articles | Metrics

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Optimize the Slope Ratios of Soil Nail Walls in Changzhou Soils XIA Jizong, LIU Jun, YANG Zhaobing 2017, 31 (1):  16-13.  Abstract ( 1134 )   Save The impact of the slope ratio on the failure modes of the soil nail wall in Changzhou soils is carefully analyzed based on the typical subsurface conditions. The influence of the slope ratio of the soil nail wall on the global stability of the deep excavation as well as the construction cost are investigated. The results indicate that the global stability and the cost effectiveness can be achieved when the slope ratios are in the range from 0.4 to 0.6. Related Articles | Metrics

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Drawdown Effect in the Dynamic Compaction Combined with the Vacuum Dewatering in the Ground Improvements for a Highway Project HOU Hongwei1, QIAN Zhihua2, TANG Shaoming2 2017, 31 (1):  20-24.  Abstract ( 949 )   Save Two trial test blocks were selected for the investigation of drawdown effect on the soil soft improvement by the dynamic compaction method in a highway project in Shangyu area. The groundwater was lowered to different depth by the vacuum dewater method. In order to compare the dynamic compaction effect on grounds with different water levels, the development and dissipation of the excessive pore water pressures as well as the ground settlement after the dynamic compaction were monitored. The results indicate that, under the higher groundwater condition, it is more difficult for the dissipation of the excessive pore pressures, and the smaller ground settlement under the unit compaction energy. With the deeper dewatering, a significant soil improvement effect can be found within a horizontal radial distance of six (6) meters and the depth of improvement was also increased. Related Articles | Metrics

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Stability Evaluation for a Debris Landslide on an Expressway Based on the Monitored Data ZHOU Xuanyang1,2, ZHANG Keneng1,2, LI Yi1,2 2017, 31 (1):  25-28.  Abstract ( 1000 )   Save Landslides in the existing soil and rock debris slopes are one of the major hazards in highway projects. In this paper, the subsurface hydrological and geological conditions of the landslide were introduced in details on a debris landslide at an expressway between station K121+100 and +330. The slip surface was determined from the site monitoring data. The main evaluation results are: 1) the slip surface of the landslide was able to be determined from the site monitoring data. The accurate determination of the slip surface from the monitored data is essential to the landslide mitigation construction and the safe operation of the highway. 2) The landslide was evaluated with the transfer coefficient method under two extreme loading conditions. It is concluded that the heavy precipitation was the major factor that contributed to the slope failure. Related Articles | Metrics

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Deep Excavation Support in Red Clay Soils In Karst Area TANG Zhengrong 2017, 31 (1):  29-32.  Abstract ( 1102 )   Save Red clay is widely distributed in Yunnan, Guangxi, Guizhou and other regions, and the red clay soil layer in karst area often has many adverse engineering and geological effects in the construction. The typical red clay soil has a hard crust with fissures near the ground surface and it is usually in soft state after a certain depth. Further, the karstic solution caves often have the difficulty to drain the water. Throughout a case history of deep excavation in red clay soils in karst terrain, this paper presents an excavation supporting method in the typical red clay soils. Related Articles | Metrics

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Structural Deformation of Type D Girders in a Guanhui Intercity Rail Tunnel through the Beijing-Kowloon Line PENG Wenxiang, JIANG Han, XU Zhi, LIU Yaqin 2017, 31 (1):  33-36.  Abstract ( 1796 )   Save With the continuous improvement of the urban subway's ongoing construction and subway network, there are a growing number of new railway tunnels under through the existing railway lines. The normal operation the rail lines and the integrity of these existing structures should be warranted. This paper presents the results of using Type D Girder to reinforce the space of Guanhui intercity rail line underneath the existing BeijingKowloon Line. The site specific engineering soil properties were obtained from the site boring and testing program. The performance of the Type D Girder was simulated by using ANSYS finite element software. Two span lengths, 20 m and 24 m, under two different operation loading conditions of passenger train and cargo train, were analyzed. The numerical simulation results are compared with the construction monitoring results and the construction safety of the future safe operation of the intercity rail line tunnel underneath the existing rail line can be warranted. Related Articles | Metrics

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Selection of Soil Improvement Methods for Deep Soft Soils underneath a Logistics Warehouse MAO Qianru1, ZENG Huajian2 2017, 31 (1):  37-41.  Abstract ( 1565 )   Save The composite ground consisting of rigid columns has received more and more applications in recent years. With its advantages over other soil improvement methods, it receives especially wider applications in the warehouse, roadway and airport projects. This paper presents a case history of applying the rigid column technique in a soil improvement of thick cohesive soft soils for a logistic warehouse project. Several feasible soil improvement methods were compared and it was found the rigid column method was the most applicable one. The bearing capacity of the rigid column and the settlement of the composite ground were checked and the results were satisfactory. Related Articles | Metrics

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Study on Natural Ventilation Effects on the Z-Shaped Urban Pedestrian Underpass GUAN Xiangyang1,2, WANG Yong 2, LI Xiongwei3, LI Mingzhong4 2017, 31 (1):  42-44.  Abstract ( 3684 )   Save The urban underground facilities in the humid and rainy climatic conditions in southern China often results in the serious condensation hazards. In order to reduce the maintenance costs after the completion of these underground structures, the natural ventilation should be encouraged in the urban pedestrian underpass as much as possible. The layout of the underpass has a strong influence on its ventilation effect and the minimization of the condensation hazards. This paper presents the underpass project of Cuiliu Street in Wuhan. The insitu ventilation tests were conducted and the numerical analyses were performed to verify the effect of the natural ventilation. The results indicate that the numerical analysis results are close to the measured results from the insitu tests. The insitu tests and the numerical analysis results verified that the natural ventilation is a better way of minimize the condensation hazard. Related Articles | Metrics

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Application of High Density Resistivity Method in the Engineering Geological Investigation of the Huaihe River Crossing Tower for a 1000 kV UHV Transmission Line ZHU Fuguang, LI Bo, LIU Xiaodong, FAN Youwang, PENG Bin 2017, 31 (1):  45-48.  Abstract ( 1285 )   Save The high density resistivity is an important geophysical survey method. Based on the different electrical resistance of different materials, the subsurface soil conditions can be surveyed by studying the electrical field of the ground. In recent years, the high density resistivity receives wider applications in the geological investigations. This paper presents the high density resistivity survey results for the Huaihe River Crossing Tower for 1000kv UHV Transmission Project. Verified by the test boring data, it is concluded that the high density resistivity method can accurately overburden soil and the bedrock. Compared with other conventional geological investigation methods, such as, test boring, cone penetration test and dynamic cone penetration test, this method has also the advantage of easy to operate, it can also collect a large amount of data and provides rich geological information. Related Articles | Metrics

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Failure Analysis and Mitigation of a Deep Excavation Support Failure in Soft Soils XIA Xiao 2017, 31 (1):  49-53.  Abstract ( 1174 )   Save As the results of overloading around the deep excavation area, water table fluctuation and the low supporting strength of the excavation support system, failures are often occur in the soft soils during the construction. This paper analyzes the failure modes of the deep excavation supporting system from the geological conditions, support scheme and loading conditions. Following the concept of control the failure first and mitigate the problem later, the guidelines for the emergency reaction, including the strengthening the supporting system and adjustment of the earth work inside the excavated area. The construction management aspects of the deep excavation are also introduced in the paper. Related Articles | Metrics

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Study of Cement-Fly ash-Gravel Composite Ground GUO Cong, ZHU Shouzeng 2017, 31 (1):  54-58.  Abstract ( 1025 )   Save Cement Fly ash Gravel (CFG) column composite foundation is one of the composite ground formed by the soil improvement methods. It receives wider applications since it has the advantages of simple construction equipment; easy installation; low overall cost and effectively improving natural weak ground. The researches on the mechanism on the CFG composite ground are fruitful in recently and many positive results are obtained. This paper presents the numerical analysis results of the performance of the CFG composite ground using ANSYS commercial software. Factors that might impact the performance of the CFG composite ground have been considered in the analysis. Related Articles | Metrics

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Soil Slaking Studies on Samples from Guilin Karst Terrain WANG Zekun1,2, GAO Wuzhen1,2,3 , LIU Feng1,2 2017, 31 (1):  59-62.  Abstract ( 1097 )   Save The free slaking studies on the undisturbed soils were performed in order to investigate the rate of the soil slaking and its influence factors. Testing data indicate that the rate soil slaking is influenced by many factors, such as, moisture content, void ratio, unit weight, and coefficient of permeability as well as the frequency of the groundwater fluctuation. The first four items are the physical properties of the soil and they are related to the soil composition, formation conditions and its surrounding environment. These factors are rarely related to the human activities. The groundwater fluctuation frequency, however, are affected by the natural environments as well as by the human activities, especially, the groundwater extraction and the irrigation. Groundwater fluctuation will accelerate the soil slaking and increase the formation of soil cavities at the soilkarst rock interface, finally, increase the development of the sinkhole collapse. Related Articles | Metrics

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Finite Element Analysis of Uplift Behavior of the Suction Caisson in Soft Clay HUO Zhiliang1, YAN Shuwang2 2017, 31 (1):  63-67.  Abstract ( 1279 )   Save Due to the soil inside the suction caisson, the suction caisson and other marine foundations demonstrate a significant difference in the uplift characteristics. For suction caissons subjected to primarily vertical tensile loads, there exist three different failure modes, “slide failure”, “bottom resistance failure” and “reversed bearing capacity failure”. Different drainage conditions at the bottom of the caisson control the applicable failure mode. In this paper, efforts are made to investigate the suction caissons as a type of foundation for the underwater structures. Numerical analyses are performed to simulate the working mechanism and evaluate the resistance of the reversed bearing capacity failure mode. The most appropriate design method was also proposed through experiments and theoretic analysis. Related Articles | Metrics

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Rock Mass Wave Velocity Visualization Model Based on the Ordinary Kriging Method LIU Chaoyang1,2, WANG Bo1,2, YANG Genlan1 2017, 31 (1):  68-72.  Abstract ( 1125 )   Save This paper introduces the basic principle of the application of the ordinary Kriging method in estimation of the wave velocity and its space variation characteristic of the rock mass. The probabilistic distribution of the rock mass wave velocity are statistically studied. The wave velocity of the rock mass are three dimensionally interpolated by using the GOCAD software so that the space variation of the wave velocity in the rock mass are obtained. The results indicate that the rock mass wave velocity has some medium to weak space variation. The three dimensional visualization of the wave velocity in the rock mass can provide quantitative and visual solutions for the geological material and can also improve the accuracy of the engineering geology analysis. Related Articles | Metrics

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Study of the Stress Ratio between Column and Soil in the Composite Ground Improved by the Rigid Columns WANG Kai, DENG Zhengyu, CHEN Yun ，CHEN Yongsheng，CHEN Liangfeng 2017, 31 (1):  73-79.  Abstract ( 1237 )   Save The accurate bearing capacity and the settlement of the composite ground usually could not be obtained by using the current design code method. The critical aspect of the composite ground formed by the rigid column is the load distribution in the columnsoil system. Based on the compatible deformation between the column and the soil, which is the objective of the design optimization, the analytical model of the columnsoilload transfer layer is established by using the elastic theory and the separate stress analysis between the column and the soil. The iteration process is used in order to obtain the stress ratio between the column and the soil. The analytical results are close to the measured results. Related Articles | Metrics

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Development of Three Dimensional Temperature Field for the Freezing Soil WANG Kai1,2，LI Shunqun1,2, XIA Jinhong3 2017, 31 (1):  80-84.  Abstract ( 1170 )   Save In the application of soil freezing method, the prediction of the 3D temperature field of the frozen curtain is an important content. This paper first provides the qualitative analysis results of the thermal transfer phenomena. Then, the formulas for the temperature field and thermal parameter predictions are provided. Finally, based on the considering phase change and latent heat, the three dimensional temperature field was predicted by the finite element software ABAQUS, which considering the results of the model freezing test results. Three different model tests by using one horizontal freezing pipe, two horizontal freezing pipes and three freezing pipes (two horizontal and one inclined pipes). Throughout the model test results and the finite element analysis results, the influence of the number of freezing pipes and different pipe locations on the rate as well as the range of the frozen curtain. The relationship between the soil temperature time are established from the comparison results of test and numerical analyses. Related Articles | Metrics

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Review of Local Scour Depth Estimation Methods around Pile Groups YIN Xiaopeng, ZHANG Biao 2017, 31 (1):  85-88.  Abstract ( 1129 )   Save The pile group received wider applications in the bridge design industry. Scour is one of the major failure mode of the bridge failures and it might results in large economical and life loss of the public. As a result, the scour depth prediction is critical to the bridge design. Currently, very few research on the influence factors on the scour depth are available. This paper presents a comprehensive review on the scour depth researches, test results and estimation methods. It is proposed that the residual soil above the local scour line is favorable to the scour depth reduction. A local scour depth estimation method is recommended by relating the local scour to the contraction scour. Related Articles | Metrics

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Prediction of the Side Shear Resistance for Drilled Shafts Socketed Into Rock CHEN Wenbo 2017, 31 (1):  89-91.  Abstract ( 1192 )   Save This paper presents the case studies of static loading test results of 65 rock socketed drilled shafts. The bedrock types for the rock sockets were sedimentary rock consisting of limestone, mudstone and shale. The static load test results are compiled into a database for the evaluation of the adequacy of the current empirical method for estimating the side friction of the rock socket. By comparing the test results and various empirical prediction methods, two methods are found to be appropriate: segmental linear prediction and square root methods. It is concluded that the segmental linear prediction method is dependent on the bedrock and the unconfined compressive strength of the intact rock. Related Articles | Metrics

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Municipal Waste Classification and Treatment in Suzhou City GE Chao1, JIN Zhousheng2, ZHANG Yu1, QIAN Yinfei3 2017, 31 (1):  92-95.  Abstract ( 1256 )   Save With rapid development of the world economy of the world and the improvement of the quality of life of the urban residents as well as the urbanization, the amount of the municipal waste increases rapidly in recent years. If these wastes are not properly treated, it might result in the contamination of water, land and atmosphere and it further has direct impact on the nation’s sustainable development as well as the proper distribution of the natural resources. In the developing county, the rapid increase of solid waste is especially a significant concern. By the end of 2013, the there are seven billion tons of municipal waste in China’s urban area and they occupy more than 800,000 mu lands. It increases with a rate of 5% each year and the waste encompassing the city becomes a major problem. This paper discusses the municipal waste classification and treatment practice in Suzhou City. Related Articles | Metrics

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Seismic Characteristics of Subgrade Liquefiable Soils under Earthquakes Conditions ZHOU Bo, YONG Wanglei 2017, 31 (1):  96-99.  Abstract ( 1434 )   Save This paper presents a case study of the liquefiable soil area in the BeijingShanghai high speed rail project. The seismic performance of the rail embankment and the distribution of the liquefiable soil are simulated with numerical analysis using concrete as the synthetic earthquake event. The results indicates that, the rail embankment has an amplification effect of the seismic reactions. Larger response spectrum values are found at the medium to low frequencies. Its principal frequency range is between 0.5 and 3.0 Hz. Local soils are found liquefied when the ground acceleration is 0.1 g; whereas, almost all soils will be liquefied when the ground acceleration reaches 0.15 g to 0.2 g. Therefore, the ground improvement to eliminate the potential liquefaction is needed. Related Articles | Metrics

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Monitoring and Analysis Stress in the Ground Anchor-Soldier -Pile Supporting Structure in High Cut Slopes WANG Zhangyun1,2, ZHANG Keneng1,2 2017, 31 (1):  100-103.  Abstract ( 1087 )   Save The high cut slope at Guixiang Road, Changsha was longterm monitored in order to study the performance of the prestressed ground anchor and soldier pile under the operation conditions. Measures to deal with the prestress loss, prestress change and horizontal displacement change with time were investigated. The relationship between the prestress level and the horizontal displacement are also discussed in the paper. It is concluded that the prestress level controls the horizontal displacement. Other influence factors on the horizontal displacement are, soil properties, rigidity of the soldier pile, groundwater. It is also concluded that the nonlinear soil properties and the nonlinear deformation properties of the ground anchor should also be considered in the design of supporting high cut slope with ground anchor and soldier pile system. Related Articles | Metrics

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Laboratory Studies on the Deformation and Pore Water Characteristics of Soft Cohesive Soils under Low Frequency Traffic Loads LUO Qiyang, LIU Yongjian, CHEN Haoran, CHEN Chuangxin 2017, 31 (1):  104-107.  Abstract ( 1029 )   Save The stateofthe art of the effect of cyclic loading frequency on the change of the dynamic pore water pressure as well as the cumulative plastic strain is reviewed and studied in this paper. The true static and cyclic triaxial test equipment SPAX200 made by GCTS was used to study the performance of the saturated peaty soft clay. The effect of traffic loading on the pore water pressure and the cumulative plastic strain in the sample was investigated. The test results indicate that, the lower the cyclic load frequency, the larger the total dynamic pore pressure value and the cumulative plastic strain in the soil sample. When the loading frequency is lower than 0.1 Hz, larger influence of loading frequency on the rate of the pore pressure and plastic strain increase. When the loading frequency is greater than 0.5 Hz, the loading frequency has negligible influence. Under the high cyclic stress level, the number of cyclic loading has a large impact on the dynamic pore water pressure and the cumulative plastic strain. However, the influence of the cyclic loading number is minimal when the cyclic stress level is low. Related Articles | Metrics

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Measurement Error Correction of a Borehole Optical Imaging Device ZHONG Jun1,2 , HUANG Yong3 2017, 31 (1):  108-111.  Abstract ( 1235 )   Save Borehole camera technology, which uses the image acquisition and processing technology, can provide the direct observation inside the borehole. The principal of the camera is mainly based on the optical theories. This technology has been successfully applied to the geotechnical engineering insitu testing and investigations. It can also provide both quantitative and qualitative analysis of the underground images. In the application of this device, without considering the differences between the human operation and the other unconventional measurement errors, the results differences among the various possible influence factors are mainly categorized in two aspects: the diameter of the borehole for the cast insitu piles and the length of the defect. In this paper, a simulation test for the measuring error of the borehole optical imaging is designed by considering the differences between the various testing items. By comparing the results of the test to the simulated defects, it is found that there is a deviation between the test data offered by the borehole optical imager and the true value and the deviation is mainly composed of the systematic error and the random error. Last, the correlation formula of the measuring error (deviation coefficient) for the borehole diameter and the length of the hole is established using the multiple linear regression method. Related Articles | Metrics

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Design and Manufacture of a Model Test Box for the Underground Space and Engineering JIA Qiang1, WANG Haodong1, LI Chenglong1, ZHANG Xin1, SHAO Kun2 2017, 31 (1):  112-114.  Abstract ( 1014 )   Save This paper presents a design sketch for the physical model test box for the underground space and engineering. The test box consists of steel plate and hot rolled steel corners connected with horizontal whalers and bolts. The four corners of the test box are formed by the steel corners and plates with bolts. This type of connection forms the skeleton of the box and it can also minimize the slip of the soil inside the box. The paper also provides the design sketch of the model test box. Related Articles | Metrics