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20 August 2016, Volume 30 Issue 4 Previous Issue    Next Issue

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Optimum Analysis of the Construction Procedure of a Tunnel with a Very Large Cross Section SHANG Wuxiao 2016, 30 (4):  407-412.  Abstract ( 1171 )   Save The DoubleSidePilotExcavation is a popular method in the tunnel excavation since it is suitable for the excavations in the Class V (worst) rock mass and it can also reduce the effect of large span in the tunnel dimensions. However, it has the disadvantages of constrained work space and long construction periods. Consider the fact that the rock mass in the project was actually better than the Class V, the optimization of the conventional DoubleSideExcavation was possible. The excavation sequence of the conventional method of left, middle and right was changed to upper left, upper right, upper middle and then, lower left, lower right and lower middle. The improved procedure was numerically modeled using GEO5 finite element software and the results were compared with the conventional procedure in terms of stress in the surrounding rock mass, bending moment in the supporting structures and the subsidence of the ground surface. The comparison results indicate that the optimized procedure is safe a reliable and further, the headroom for the construction was also able to be increased and therefore, the efficiency could be improved. Related Articles | Metrics

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Application of the Secant Pile Structure in the Deep Excavation and its Numerical Analysis YUAN Fuchang， CHEN Guanghai 2016, 30 (4):  413-415.  Abstract ( 1274 )   Save This paper presents the numerical analysis results of using the secant piles as the supporting structure for the deep excavation in Nanchang. The displacements of the supporting structure are predicted by using MIDAS 4.0 finite element software as well as Lizheng geotechnical software. The analytical results are compared with the monitored data. Related Articles | Metrics

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Mitigation of Collapse of Manually Excavated Caissons in Karst Terrain CHEN Fei1, GONG Ping2 2016, 30 (4):  416-418.  Abstract ( 1237 )   Save This paper presents the mitigation of the collapse in the manually excavated noncircular oblong caisson in karst terrain. The causes of the collapse were investigated throughout the site specific conditions, the collapsed caissons were treated with grouting and optimize the protective layer of the excavated caisson. Related Articles | Metrics

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Karst Rock Cavity Mitigations for a Subway Station in Wuhan ZHANG Peng, HE Lihong， DONG Yong 2016, 30 (4):  419-422.  Abstract ( 1311 )   Save This paper describes the engineering geology aspects of a subway station in Wuhan and its karst rock cavity distributions. The impact of the karst rock cavities on the subway structures and principles of the hazard mitigations as well as the treatment procedures and their quality control method are also discussed in the paper. Related Articles | Metrics

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Geological Hazard Assessments and Mitigations of a Water Diversion Project HUANG Jusong1, QING Cuigui2, LI Junming2 2016, 30 (4):  423-426.  Abstract ( 1367 )   Save This paper presents geological hazards evaluation results for a water diversion project. Based the systematic investigation of the geological environments for the pivot structures, the hazard evaluation utilizes the stereographic projection and quantitative scoring methods. The results indicate that the project area has a medium complicated geological conditions, and the slopes at the aprons of the main diversion tunnel as well as the construction supporting tunnel have the medium probability of geological hazards, such as, rock collapses; slope instabilities and mudflows. Approximately 82.9% of the project areas have a low geological hazard rating and are suitable for the engineering projects. The mitigation approaches for the potential geological hazards are also proposed. Related Articles | Metrics

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Evaluation and Mitigation of a Landslide in Pinxiang Middle School, Jiangxi province LE Qiaoli， YANG Xueqiang 2016, 30 (4):  427-430.  Abstract ( 1752 )   Save Landslide instability is a common but complicated as well as potentially disasters process. The study of landslide stability has been a classical subject in the field of geotechnical engineering. This article is based on a landslide of Pingxiang middle school. The shape of the landslide slide failure surface shape is segmental according to the monitoring data. Therefore, the transfer coefficient method is used to analyze landslide stability. In addition, this article also discusses some engineering measures to manage potential landslides. Related Articles | Metrics

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Slope Stability Analysis Using SLIDE Software WU Fagen1， GAO Shuang2 2016, 30 (4):  431-434.  Abstract ( 1920 )   Save This paper presents a case history of the analysis and the design of a failed slope in Dongguan. The software SLIDE by Rocscience of Canada was used and the slope mitigation measures were proposed based on the analytical results. Related Articles | Metrics

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A Large Water Treatment Plant Site on High Fills ZHU Junsong, YIN Keming, LUO Kunsheng， MA Gaoqiang 2016, 30 (4):  435-439.  Abstract ( 1356 )   Save This paper presents the design aspects of a typical water treatment plant site on the high fills in the mountain area. The site requirements of the conventional water treatment process flow are analyzed. The slope stability and the allowable settlements for various structures are discussed and the mitigation methods are also recommended. Related Articles | Metrics

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Application of the Deep Borehole Pre-Splitting Blasting in the Excavation of Vertical Shaft for a Hydraulic Structure FEI Botao1, XU Kun2 2016, 30 (4):  440-442.  Abstract ( 1292 )   Save This paper presents a case history of application of the 30 meters deep borehole pre-splitting blasting technique in the excavation of a vertical shaft for the flood discharge tunnel in Houziyan Hydroelectricity Station. The quality requirements for the excavation were achieved; the construction safety as well as the construction schedule were able to be met. This deep borehole pre-splitting blasting is proved to be a viable way for the vertical shaft excavation. Related Articles | Metrics

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Stability Evaluations for a Landslide at Shiwangmiao, Fengjie County YANG Yang 2016, 30 (4):  443-446.  Abstract ( 1212 )   Save Near Town of Kangle, Fengjie County of Chongqing City, the Shiwangmiao landslides distributed on the left bank sloping area of Meixi River, a tributary of Yanzte River. It is a secondary landslide developed on the accumulation of the colluvial of the parental bedrock mass and eroded from hills and river valley geometry where underground water consists of perched water and water from bedrock fissures. Based on detailed evaluation of shapes of landslides, geological structures and failure characteristics, the landslide stability analyses under various conditions were performed by using the transmitting coefficient method. Combined with the quantitative analysis of the landslides, the result showed that stability of existing slopes under the heavy precipitation conditions. Related Articles | Metrics

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Soft Soil Improvement for Airport Runways in Southeast China CHEN Qinwen 2016, 30 (4):  447-481.  Abstract ( 1243 )   Save Soft soils are frequently encountered in the airport runway constructions in Southeast China. The high compressibility and low shear strength of these soft soils can often result in large areas of differential settlement and shear failure within the runways. Therefore, the soil improvement is the critical issue in the airport construction. This paper presents the code requirements of total and differential settlement, strength and stability aspects in the runway construction. The results of four different soil improvement projects and their correspondent soil improvement recommendations are also presented. Related Articles | Metrics

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Application of Umbrella Anchors for the Mitigation of Strong Expansive Soil Landslides in a Water Transmission Project in Northern Hubei GONG Jianghong1, YAO Dengyou1, REN Jiali2 2016, 30 (4):  452-456.  Abstract ( 1504 )   Save The expansive soils within a water transmission project limits were extensively studied with site test pits sampling, laboratory mechanical property testing and CT scanning of the failure planes of the samples collected from the test pits. These test results indicate that the landslide failure modes in the strong expansive soils are mainly related to the failure mode that controlled by the strength of the fissures. Based on the failure mode characterization, the feasibility of the umbrella anchor in the mitigation of the landslides in strong expansive soils, installation procedure are discussed in the paper. The construction monitoring data indicated that the mitigation was successful. Related Articles | Metrics

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Application of CementGravel Mixing Soils in the Chashan Lock Project in Linyi LIU Yang1, FU Yongkun2, MA Jundong 2 2016, 30 (4):  457-459.  Abstract ( 1423 )   Save Challenges in the cementgravel mixing soils are the controlling of cement during the construction, ununiformed mixing results and low mixing efficiency. This paper presents measures that can improve the construction quality of this technology. Case history of Chashan Lock Project in Linyi indicates that better mixing quality; degrees of compaction for the mix soils and the construction efficiency could be achieved while the cost of installation could also be reduced. \= Related Articles | Metrics

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Applications of the Strength Reduction Method in the Stability Analysis of Slopes near Buildings WU Biao1, WANG Zhibin2, AN Yonglin2， QIU Lei2 2016, 30 (4):  460-463.  Abstract ( 1410 )   Save This paper presents the slope stability analysis results of a potentially instable slopes in Anhua County. The three dimensional finite analysis model was established throughout the geotechnical investigation results and site specific topographies. The MohrCoulomb failure criteria and the strength reduction method were used in the analytical model. The numerical results are compared with the results from the limit equilibrium method and it is concluded that the strength reduction can be used in FLAC3D analysis. Related Articles | Metrics

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Slope Stability Analysis Based on Shear Strength Reduction Method CHEN Junxin 2016, 30 (4):  464-466.  Abstract ( 1366 )   Save A twodimensional numerical model for a slope stability project was established by using the finite difference software FLAC. The stability concern was mitigated by ground anchors and the slope before and after the reinforcement were numerically analyzed. The analytical results indicate that the natural slope was marginally stable under the normal conditions but it might be unstable under the heavy precipitations. After the installation of ground anchor, the factors of safety under both normal and extreme conditions are greater than 1.25. The potential slip surface was able to be eliminated. Related Articles | Metrics

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Influence of Excavation Sequences on the Stability of Soil-Rock Dual Structure Formations REN Hengfei, YANG Zeping, LIANG Haian, LUO Xirui 2016, 30 (4):  467-470.  Abstract ( 1552 )   Save This paper discusses the effect of different excavation sequence on the stability of the soilrock dual structure formations. Four different excavation sequences were studied in a deep excavation project in Jingde, Jiangxi Province. The onestep, sequential stepped, skipped excavation and sequential skipped excavation are numerical simulated and are performed in the construction and the slope surfaces at each type of excavation were monitored. The monitored data indicated that the excavation would result in the gravitational stress redistribution at the bottom of the excavation. The sequential skipped excavation method would be beneficial to the stability of the excavated area. Whereas, the stepped excavation method would reduce the heave at the excavated area. Analyses of different excavation methods can accurately simulate the excavation sequence on the stability of the excavated slopes and the excavation method can be optimized. Related Articles | Metrics

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Deep Excavation Supporting Design Optimization under Complex Conditions WANG Li1， ZHANG Junping2 2016, 30 (4):  471-475.  Abstract ( 1981 )   Save The supporting cost is a significant portion in the deep excavation and foundation engineering. The conventional deep excavation supporting design is usually conservative in order to reduce the supporting failure during the construction. However, the cost of the supporting is usually not optimized as a result of this conservative design. This paper presents a deep excavation case in the complicated subsurface conditions in Xi'an City. The deformation and stress changes in the supporting system have been numerically predicted and measured. The numerical analyses on the supporting system verified that the design of the system is safe and reliable. Further, the analytical results also confirmed that the parameters used were reasonable.  The supporting system optimization was performed based on the results of numerical analysis; the ground anchor and the dimensions of the secant piles are optimized and the cost was able to be reduced. Related Articles | Metrics

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3D Finite Element Analysis of the Deep Excavation on the Stress and Strain in Pile Groups ZHAO Xin1,3, LU Mingyue2,3， DUAN Xianming3 2016, 30 (4):  476-480.  Abstract ( 1324 )   Save The large deep excavation of the stress and strain in pile groups was analyzed with three dimensional finite elements analyses. The stress strain characteristics in the pile group are significantly different from those of in the single pile. For pile groups under the bottom of the excavation, the axial stress in the pile increases in the depth of the excavation. The location of the maximum force in the pile changes from the top to the middle part of the pile. Whereas, in the single pile (without pile cap), the maximum axial force is located at the lower portion of the pile. At the same excavation depth, the smaller axial force could be found in piles near the slurry wall; large axial force can be found in piles that are close to the center of the excavation with a larger pile deformation and mobilized side resistance in piles. Due to the lateral deformation of the supporting structures, piles that are closed to the supporting structures have large bending moments. As a result, these piles have large deformation in the upper portion of the pile. Related Articles | Metrics

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Review of the Analytical Methods of Stress and Strain in the Pile-Supported Geosynthetic Load Transfer Mat LI Xiaolong, SHI Hongyan 2016, 30 (4):  481-485.  Abstract ( 1543 )   Save This paper provides thestateoftheart review of analysis methods of the pile supported geosynthetic load transfer mat. The load distributions and the bases for the analysis of the load transfer mat of each method are discussed in the paper. The results indicate that the inverse triangular load distribution assumption is more reasonable comparing with the uniform or triangular load distributions. For the two dimensional analysis methods, the deformation in the geosynthetics assumptions defined by the parabola and circular methods in Germany design code are better compared with other methods; however, the Germany design code method could not estimate the change of tensile stress along the longitudinal direction. The plate assumptions in the three dimensional analysis can be applied in the geogrid reinforcements but it is not applicable to the geotextiles or geomembranes. Related Articles | Metrics

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Deformation Criteria for Uplift Anchors HE Shanshan, WANG Xianneng 2016, 30 (4):  486-490.  Abstract ( 1349 )   Save The uplift anchors for the buoyancy design in underground projects have received wider applications and become increasingly matured. However, there are no current design and construction code available for the guidance. This paper presents an allowable deformation criteria for the uplift anchors throughout the theoretical analysis of the deformation of the uplift anchors. A case history of the uplift anchor in an underground project Shenzhen is also presented. The deformation of uplift anchors is analyzed by using finite element analysis. The deformation of the uplift anchors in the numerical analysis is obtained and is found to be close to the analytical value. Related Articles | Metrics

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Deformation Response of the Unsaturated Soft Clay under Water Level Fluctuations GAO Ming, CHAI Shouhong 2016, 30 (4):  491-494.  Abstract ( 1360 )   Save Soft clay that deposits offshore has poor engineering properties, strong thixotropic and rheological property. Under the fluctuation of the water level, significant settlement deformation and rebound deflection might occur. Unsaturated Shanghai soft clay from the water fluctuation zone was used to conduct experiments for its deformation characteristics. The cyclic watering and draining conditions in the conventional oedometers were manually created in order to simulate the impact of the water level fluctuations as well as the cyclic numbers on the deformation properties of unsaturated soft soils. Results of these tests can be used in the interpretation of the unsaturated soft soil properties impacted by the groundwater level fluctuation induced by the cyclic extraction and recharge of groundwater. Related Articles | Metrics

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Feasibility of Leaking Sealing Using PVA Gels ZHANG Shihua1, PENG Zhenbin2, QIN Yifeng2， WU Dan2 2016, 30 (4):  495-498.  Abstract ( 1442 )   Save The principles of the formation of the gel as reactions between polyvinyl alcohol (PVA) and borax are briefly introduced in this paper. The PVA gel can be potentially used as a sealing material for the leaking. The various mix designs of the PVA gel were laboratory tested and the optimized mix design was obtained. The field tests indicated that this material can be satisfactorily used in broken soils with small fissures. Related Articles | Metrics

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Comparative Analyses on the Geotechnical Investigation of a Large Oil Tank Using Different Codes WU Jian1,2, QIAN Ming2 2016, 30 (4):  499-503.  Abstract ( 1525 )   Save Comparative analyses were performed on the geotechnical investigation of a large oil tank by using different code requirements in this paper. Namely, The National Standards (GB) Geotechnical Investigation, Geotechnical Investigation Code for the Oil, Gas and Pipelines; Geotechnical Investigation Code for the Petroleum and Chemical Engineering Projects and Foundation Design Code for the Steel Storage Tanks for the Petroleum and Chemical Engineering are compared. The actual geotechnical investigation for the oil tanks can be optimized and the economic construction cost can be achieved by using appropriate standards. Related Articles | Metrics

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The Crack Propagation in a Flushing Sluice Using Non-linear Finite Element Method ZOU Fei1,2， LU Yu1 2016, 30 (4):  504-506.  Abstract ( 1065 )   Save Flushing sluice is a hydraulic structure for transporting silt of upper stream of the river or the canal using the fast water flow. The cracks are often encountered at the bottom slab and caisson of the lock structure. The propagation of these cracks in the relative integral area, cracked region and recovered strength conditions are analyzed by nonlinear finite element method. Research conclusions can be obtained throughout the statistical summary of the volume of elements with open cracks, the analysis of the sensitivity of the recovered strength as well as the comparative study of the stress ratio of the cracked area. The results show that, when the material strength of the cracked region recovers to 50% of recovered strength, the volume of the cracked elements will not change, and the stress state has basically returned to the fully recovered state and the safe operation of flushing sluice can then be assured. Related Articles | Metrics

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Assessment of a Traveling Pluviation Apparatus for the Preparation of Sand Samples CAO Mingming, XIAO Zhaoran 2016, 30 (4):  507-509.  Abstract ( 1378 )   Save The sample preparation is one of the most important procedures in the centrifuge tests. The key issue is to prepare various samples with designated densities. This paper presents a new sample preparation method that can prepare sand samples with various densities by using the traveling pluviation apparatus (TPA) for the centrifuge tests. Throughout the calibration tests, the target density relationships among the dropping height of sand, diameter of the pipe are obtained. The calibration tests also indicate that this apparatus can provide various densities of the sand samples by adjusting the sand dropping height, and the diameter of sand pipe. Related Articles | Metrics

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Seismic Centrifuge Studies of Sliding Resistance Caissons under Excavation Conditions 2016, 30 (4):  510-513.  Abstract ( 1023 )   Save Currently, there is no published references of seismic centrifuge test results on the sliding resistance caissons under the excavation conditions. This paper presents the first seismic centrifugal testing result on this topic. The input of the seismic waves are the actual earthquake recorded on May 18, 1940 Imperial Valley Earthquake at a site in El Centro, California. The input vibrations have a total of 1559 data points with a time interval of 0.02 seconds. The maximum acceleration duration the excavation was assumed to be 0.38g due to the lacked of the recorded maximum acceleration value. The bending moments of the sliding resistance caisson were measured by the strain gages and the deformations at the top of caisson were measured by the laser distance measurement. The seismic earth pressure and the accelerations at different depths were also measured by the earth pressure cells and the accelerometers that were embedded in the soils. The bottom of the caissons in the centrifuge test were in the fixed condition. Related Articles | Metrics

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Comparative Study of Two Commercial Consolidometers LIU Min1，ZHANG Xuelong2 2016, 30 (4):  514-516.  Abstract ( 1173 )   Save Two commercially available consolidometers are introduced in terms of their working principles, operative procedures, compressive pressure control, level of automations as well as advantage and disadvantage of each type of equipment .Throughout commercial laboratory consolidation tests, each type of equipment could not replace the other type. In some projects, the combinations of both types of the consolidometers are satisfactory. It is concluded that, under the state of the practice, the combination of both type of equipment is necessary from the comprehensive considerations of the cost, efficiency as well as the data reliability. The improvement recommendations on the commercial consolidometers are provided. Related Articles | Metrics

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Discussions on the Methods of Determining the Bearing Capacity of Foundation in Taihu Lake Area PANG Bin, YANG Shouhua, ZHAN Xinjie, HOU Yanle 2016, 30 (4):  517-519.  Abstract ( 1265 )   Save Bearing capacity of foundations is one of the important parameters in the foundation evaluations. In this paper, the calculation methods of bearing capacity of foundation based on the laboratory tests and the insitu test are introduced. Two methods are utilized to determine the bearing capacity of foundation in a project case history. The magnitude of the bearing capacity of the foundation with different methods are compared and are analyzed. The results indicate that the determining of bearing capacity of foundation with a single method is not accurate. The combination of different methods should be used in order to accurately obtain the value of bearing capacity of the proposed foundations. Related Articles | Metrics

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Dynamic Shear Modulus and Damping Ratio of Soft Soils of Tangshan Caofeidian Coastal Area HAO Bin1, ZHAO Yucheng1, LIU Zhenyan2, LI Zhanling2, XIE Yang1, ZHANG Xiaoxing1 2016, 30 (4):  520-523.  Abstract ( 1184 )   Save The soil cohesive soil samples were collected from a near shore wind mill farm project in the coastal area of Caofeidian, Tangshan City. The dynamic soil modulus and damping ratios were tested through GDS dynamic triaxial test by simulating the cyclic wave actions. The effect of dynamic stress magnitude and confining pressures on the dynamic modulus and damping ratios were studied. The results indicate that the dynamic shear modulus and damping ratios increase with the cyclic stress magnitude and confining pressures. The initial dynamic shear modulus of the costal soft soils in Caofeidian area are also obtained. Related Articles | Metrics

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Experimental Study on Compressive Strength of Coral Aggregate Concrete Mixed with Seawater SHEN Jinlin 2016, 30 (4):  524-526.  Abstract ( 1407 )   Save The performance of the coral reef sand concrete mixed and cured by the seawater is significant to the construction of islands and reefs in the South China Sea. In order to study the compressive strength of those concrete samples, the uniaxial compressive strength of 100 × 100 × 100mm test cubes under different ages (3d, 7d, 14d, 21d, 28d) were tested, and the cement types, watercement ratio and other factors that might affecting the strength of concrete were explored. The results indicated that, the performance of coral sand concrete cube compressive strength variation is consistent with the ordinary gravel concrete. The range of the compressive strength increases with the decrease of watercement ratio; and the higher the cement grade, the higher the ultimate compressive strength is. With the same strength index, the mix design with Portland cement has the lowest strength. In the practical coral reef construction engineering, a strength index of 425 should be used. Related Articles | Metrics

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Laboratory Tests of Mechanical Properties of Coral Sand Samples from a Coral Reef QIAN Wei 2016, 30 (4):  527-532.  Abstract ( 1376 )   Save The properties of the granular debris deposits at upper portion of the coral reef and island have critical influence on the development of these reefs and islands. The strength and compressibility of the calcareous sand samples collected from the development of a coral reef were laboratory tested by using large scale direct shear device and the high pressure oedometer. The results indicated that, under the similar grain size distribution, the apparent cohesion value is effected by the rate of shearing and the content of coarse grains 9P5). Large shearing rate results in a smaller apparent cohesion value, whereas, the increase of P5 leads to an increase of apparent cohesion. The compressibility of the coral sandgravel mixture is impacted by the gravel composition and the quantity of the sand. At the same time, the moisture content of the mixture will affect the compressibility. Related Articles | Metrics