Papers by Author: Liang Cao

Abstract: Based on the principles of conventional oedometer tests, half mold consolidation apparatus which attained Chinese Patent Certificate of New and Practical Device was designed for non-saturated soil's micro-observation with axial drainage conditions. By half mold consolidation tests, we could get similar stress-strain curves at different water content, which could illustrate the feasibility of the new apparatus. Besides, on the application of DPDM (the digital photogrammetry for deformation measurement) technology, the deformation fields of the silty clay were analyzed under monotonic increasing load, which could obviously show the macro mechanics properties by digital image analysis. According to the distribution of deformation fields, the analyzing area could be divided into three parts from top to bottom sequence: soil in top area subsided with upper porous-stone in balance; the deformation in the central area was changing the most whereas there had always been inapparent changes near down porous-stone. Such study could put forward a new conception for the development of conventional soil tests, which could be helpful to further establish the theoretical constitutive model for silty clay.

Abstract: By analyzing the association relationships between sand particle mechanics parameters and microscopic characteristics, this paper qualitative establishes the association table including physical and mechanical parameters such as the water content w, void ratio e and shear stress, and micro-parameters of sand particle such as particle number n, long axis L, short axis B, x, y coordinate of the centroid of particle, y-axis projection length, degree of eccentricity and orientation arrangement. Then the macro-micro relationship table of sand was established. The macro-micro relationship table of sand indicated that three micro-parameters of sand particle including particle number n, long axis L, short axis B have closely relationship with the water content w, void ratio e and shear stress. And the qualitative research between the sand particle mechanics and microscopic characteristics laid the foundation for the macro-micro association research.

Abstract: Thermal properties are very important physical indices of soils which could be applied to estimate the thermal capacity of environmental control system of underground infrastructures. At present, the existing ideal prediction models of thermal conductivity were not suitable for soil which in fact had very complicated internal fabric. For this purpose, SEM images of soil specimens were taken and digitized with binarizing process by using self-developed software package – ImgAnsys for image analysis, and the treated images were successfully input into ANSYS and analyzed based on the two-dimensional heat transient transferring model. It was found that the simulating results were closely consistent with experimental results, which could illustrate the feasibility of this new experimental method.