Research Of Duncan-Chang Model For Granite Residual Soils In Fuzhou Area

Abstract:The natural granite residual soil is a product of particular geographical, climatic, geological environment, with special components and structure characteristics, belonging to the regional special soil. Its special structure and sensitivity of water directly affects the mechanical properties of granite residual soil. In engineering, the structural foundation tends to produce sudden destruction in the absence of warning. Therefore, the research of the granite residual soil structure to the structure design and foundation reinforcement design on granite residual soil region has very important significance. Granite residual soil in Fuzhou area widely distributed. In recent years, with the rapid economic development, the size of new buildings on granite residual land in Fuzhou is growing, pile excavation or construction works carried out in the granite residual soil is also more and more. Therefore, the study of the granite residual soil in Fuzhou area to be further deepened.Duncan-Chang model can reflects the main rule of soil deformation and the parameters of the model can be obtained from conventional triaxial tests, thus the Duncan-Chang model is widely used in engineering practice. However, the Duncan-Chang model is based on the remolded soil. So, when it is used in natural soil may be quite different from the actual situation. However, the study on the soil structure is still immature, there are some difficulties to establish a new model.This paper first introduces the current research situation of Duncan-Chang models at home and abroad, getting the basic physical properties by basic physical mechanical property test of undisturbed soil samples on Fuzhou area of granite residual soil. A series of triaxial consolidation drained tests were done of undisturbed soil samples and different content of remolded granite residual soil samples, getting the stress-strain curves. Through the calculation and analysis of the Duncan-Chang model parameters under different water conditions of remolded samples, learned that the water content of the granite residual soils had influence on Duncan-Chang model parameters:with the growth of the moisture content, the shear strength indexes c and φ, the initial deformation modulus Et and the parameter K continued to decrease, while the parameters n and Rf continued to increase. Aiming at the deficiency of Duncan-Chang model, considering the influence of structural factors of soil, combining concept of damage to modify it, and in viewing of the undisturbed granite residual soil granite residual soil triaxial consolidation drained tests, fitting the experimental data of the modified Duncan-Chang model and the original model parameters by used MATLAB to verify the rationality of the modified model.