Research On Pile-Tip Bearing Capacity Of The Tertiary Mudstone In Guangxi

Firstly the paper introduces and generalizes the distribution, engineering classification and engineering properties of the tertiary mudstone in Guangxi. Then the paper analyzes the pile-tip bearing behaviour of the tertiary mudstone in Guangxi. Last aiming at the tertiary mudstone in Nanning Basin, the paper studies on its bearing capacity of pile tip by methods of in situ plate loading test , rigid-plastic body theory and elasto-plasticity theory . In the paper, Terzaghi's bearing-capacity problem is expounded, and the Terzaghi's bearing-capacity equation modified by the values of small plate loading test is gained. According to elasto-plasticity theory, with the help of finite-method program ANSYS, the paper undertakes the computer analogue tests about the bearing capacity of pile tip arranged by orthogonal principle, and attains the relations of pile-tip bearing capacity to embedment depth, pile diameter, cohesion, internal friction angle and modulus of deformation. By the means of mathematical statistic, regression equation of the ultimate bearing capacity calculated by finite element method is gained through the regression analysis of 81 group data from the computer analogue tests. By comparison and analysis of the values calculated by finite-element regression equation and the values of in situ loading test, the regression equation is gained which calculates the size effect for base resistance of large diameter pile. Terzaghi bearing-capacity modified equation and finite-element regression equation have good reliability and practicality , which will have an important reference value on preparing the local correlative standards of constructing work in Guangxi.