Triaxial Test On Unsaturated Soil Of Newly Deposited Silty Clay

According to the positive and negative pore water pressure,soil mechanics can be divided into saturated soil mechanics and unsaturated soil mechanics.Previous studies have shown that the matric suction in unsaturated soils is a key factor affecting the strength,permeability and deformation of soils,and has important practical significance in engineering applications such as foundation bearing capacity,foundation pit earth pressure and slope stability.For the first time,the newly deposited silty clay in the unsaturated state on the East Bank of Xinkai River in Changchun City is taken as the research object.The soil water characteristic curve,shear strength and its parameters,compression deformation and other aspects of the newly deposited silty clay are mainly studied with the help of high-tech indoor geotechnical testing equipment such as unsaturated soil triaxial apparatus and pressure plate apparatus.The recent settlement of the unsaturated state by matrix suction is mainly discussed The influence of physical and mechanical indexes of silty clay.The experimental results show that the VG model has a good fitting effect on the soil water characteristic curve of the newly deposited silty clay.With the increase of matrix suction,the initial stiffness,secant modulus,shear strength,cohesion and compression modulus of the unsaturated silty clay increase obviously,and the internal friction angle increases slightly.The newly deposited silty clay before and after consolidation compression The water content and void ratio decrease with the increase of matrix suction,and the decrease trend of water content and void ratio before compression is more obvious.The foundation pit in this area often adopts row pile supporting structure.Based on the theory of double stress variable shear strength and FLAC3 D software,the influence of matric suction on pile inclination,ground settlement and active earth pressure of cantilever row pile supporting system is simulated and analyzed.The influences of excavation process and matric suction on displacement and earth pressure of the model are analyzed.The simulation results show that with the excavation process,the horizontal displacement and ground settlement of the pile body are increasing,and the active earth pressure strength acting on the side of the pile body is decreasing;when the excavation is completed,the change of matrix suction has a significant impact on the ground settlement and pile body tilt,and the active earth pressure is also decreasing.This research has certain scientific research value,economic value and engineering significance.This paper makes up for the lack of research data on engineering properties of recently deposited silty clay,and preliminarily discusses the application of related theories and methods of unsaturated soil mechanics in this area,so as to provide reliable,accurate and applicable basic technical parameters for safe and sustainable development of urban construction,geotechnical engineering design and construction.