Study on Physical and Mechanical Properties of the Water-rich Silt Fine Sand Stratum in an Area of Hangzhou

In order to deeply explore the basic physical and mechanical properties of the water-rich silt fine layer, taking the water-rich silt sand layer in Hangzhou city as the engineering background, a series of physical and mechanical tests including density, particle analysis, direct shear, unconfined compression and triaxial compression are carried out. On-site drilling reveals that the area in Hangzhou is mainly composed of sandy silt and silt fine sand mixed with silt. The particle analysis tests on the silt sand stratum soil show that the content of particles larger than 0.075 mm in the silt fine sand sample accounts for 50%~75% with a majority distribution range of 0.075~0.25mm. It is a typical silt fine sand with a single particle size and poor gradation. Laboratory mechanical tests of soil samples show that the unconfined compressive stress-strain curves of the soil sample show a characteristic of elastic-plastic-ductile. The failure mode is shear failure, and the angle of the shear fracture zone is about 65°. The cohesion and friction angle of the soil samples obtained from the direct shear, unconsolidated and undrained, and consolidated undrained triaxial tests are approximately 7.67~13.50KPa and 36.35~41.54° respectively. The results of three are closer but show an increasing trend. The research results can provide reference significance for engineering construction design and construction in Hangzhou area.