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Wang X.-Q.,Wuhan University of Technology | Zou W.-L.,Wuhan University | Luo Y.-D.,Shenzhen Geotechnical Investigation and Surveying Institute Co. | Deng W.-D.,China Merchants Chongqing Communications Research and Design Institute Co. | Wang Z.,Wuhan University
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Under the circumstance of single-dehydration process and dry-wet cycle process, the soil-water characteristic curves (SWCCs) of Chongqing compacted clay soil samples with different compaction degrees and different gradations were respectively obtained by means of temple apparatus and pressure plate apparatus. The testing results show that: (1) After compaction degree exceeding 90%, the linear sections of SWCCs of the soil samples with different compaction degrees close each other, which indicates that the SWCCs gradually tend to stability within the common matrix suction changing scope of this compacted clay soil. (2) With the increment of compaction degree, the hysteresis loops of dry-wet cycle process gradually move upward, and the SWCCs change from steep shape to mitigative shape; this indicates that the moisture in the soil samples is more difficult to be intaken or drained out, which is beneficial to the stability of subgrade. (3) Under the same water content, there is a boundary of compaction degree of 85% for the compacted clay soil, the matrix suctions of the soil samples with less than or more than this compaction degree basically do not change with compaction degree changing. (4) Under the same compaction degree and water content, the matrix suctions of the soil samples with more coarse grained soil are more smaller; and the hysteresis loops of SWCCs are also smaller, which indicates that the influence of dry-wet cycle process on coarse grained soil is smaller. Therefore, coarse grained soil is more suitable for use as fill material of subgrade. Source


Luo Y.-D.,Wuhan University | Luo Y.-D.,Shenzhen Geotechnical Investigation and Surveying Institute Co.
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Compacted soil, which widely exists in many sorts of engineering projects, is commonly unsaturated soil; and its physico-mechanical characteristics are influenced by soil moisture. Because of the difficulty in matric suction measurement, it is hard to apply the unsaturated soil strength theory to compacted soil projects. This paper aims to research how much influence on shear strength of compacted soil when soil moisture varies, and tries to find an easy and useful way in determining the shear strength of unsaturated compacted soils. Research works start from the theory of unsaturated soil, and the mechanism, with which soil moisture affects shear strength of compacted soil, is analyzed. Triaxial shear test results of five sorts of unsaturated compacted soils are rearranged and analyzed; and strength parameters of direct shear test are collected and arranged from data of some filled and compacted soil projects. Analysis shows that matric suction contributes a considerable portion of shear strength in the compacted soils; and the influence of soil moisture on shear strength of compacted soil is obvious and can not be neglected. A fine linear relationship between logarithmic saturation and cohesion of compacted soil is found in project data; and a simple method for calculating shear strength of compacted soil, which can take saturation degree influence into account, is presented. Source


Xu X.-C.,CAS Wuhan Institute of Rock and Soil Mechanics | Zhou W.,Shenzhen Geotechnical Investigation and Surveying Institute Co. | Chen S.-X.,CAS Wuhan Institute of Rock and Soil Mechanics
Yantu Lixue/Rock and Soil Mechanics | Year: 2015

Environmental temperature is one of the external factors that influence the cracking of expansive soil; and initial water content and dry density are the important internal factors. In order to study the cracking characteristics and influencing factors for expansive soil, the tests of cracking process are conducted on remolded Nanyang expansive soil with different initial water contents and different initial dry densities. The results indicate that cracking process can be divided into three phases, i.e. soil shrinkage-crack generation, rapid crack expansion and stabilization. The ratio between shrinkage area plus crack area and initial area is defined as fissure ratio, which can describe not only the drying shrinkage characteristics but also the cracking characteristics, and is suitable for depicting the crack propagation process of small size sample. Temperature has a certain extent influence on the dehydration process of expansive soil; a higher temperature can result in a small fissures ratio. Initial water content is positively related to cracking degree. Initial dry density has a negative correlation with cracking degree. ©, 2015, Science Press. All right reserved. Source


Hu C.,Wuhan University | Yan X.,Shenzhen Geotechnical Investigation and Surveying Institute Co.
Proceedings of 4th International Workshop on Advanced Computational Intelligence, IWACI 2011 | Year: 2011

Effective mining technology can extract the spatial distribution pattern of the road network traffic flow. In this paper, the similarities between traffic flow objects with spatial temporal characteristics were measured by introducing the Dynamic Time Warping (DTW) and the shortest path analysis method. We proposed a kind of clustering analysis method for road network traffic flow data. So that traffic flow data objects with similar properties and space correlation are clustered into one class, which found that the spatial distribution pattern of road traffic flow. The experimental results show that the method was effective. The road network was classified reasonably, and classification results could provide traffic zone division with decision auxiliary support. © 2011 IEEE. Source


Yang G.-H.,China Institute of Water Resources and Hydropower Research | Yang G.-H.,Wuhan University | Luo Y.-D.,Wuhan University | Luo Y.-D.,Shenzhen Geotechnical Investigation and Surveying Institute Co. | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

Foundation settlement calculation has been a hot and difficult problem in geotechnical engineering study. The difficulty lies in large differences between the geotechnical parameters of indoor tests and in-situ tests. Especially for the sand foundation and hard clay foundation with high structural strength, there is a large error between calculated settlement based on the laboratory test parameters and the actual one. The tangent modulus method based on the in-situ plate loading tests to determine the calculation parameters can overcome this shortcoming and reflect the non-linearity of foundation settlement, which is a new progress of foundation settlement calculation. However, compared with other tests, the in-situ plate loading tests have more difficulties, and it is also difficult to reflect the characteristics of deep soils. By using the systematic geotechnical test data by Riverside Campus, Texas A & M University, United States, the feasibility of the tangent modulus method for calculating the nonlinear settlement of sand foundation is examined, and then the tangent modulus method by adopting lateral pressure tests and static cone penetration tests to determine different soil layers is studied and lastly the results of loading tests on different plate sizes are verified. The results show that the calculated parameters needed in the tangent modulus method determined by the lateral pressure tests and static cone penetration tests are feasible. In addition, when they are used in the tangent modulus method to calculate the load experimental curves of different plate sizes, the calculated nonlinear curves have good consistency with experimental ones. This method is a simple and easier access to deep soil parameters, providing an easier way of the determination of the parameters of the tangent modulus method. It is of great significance in solving problems of foundation settlement calculation and in promoting the development of the design theory of the foundations. Source

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