A study of the engineering geological characteristics and physico-mechanical property of rock and soil layers in the Pearl River mouth area

Based on the geological survey results along the Hong Kong-Zhuhai-Macao Bridge, the Shenzhen-Zhongshan Bridge, and the Humen Bridge, geological characteristics of the rock and soil layers in the Pearl River Mouth areas are analyzed. The rock and soil layers can be divided into five layers: silty soft soil layer, clay silty clay layer, medium-coarse sand layer, residual soil layer and weathered rocks. Combined with the hydrodynamic environment, sediment types, borehole comparison and geological section, the study area can be divided into four types of sedimentary areas: the estuary sandy sedimentary area, tidal mud sedimentary area, mud-sand mixed sedimentary area and shallow sea mud-sand mixed sedimentary area. The physical properties are examined, with the increase of depth, the moisture content decreases, the fast shear cohesion increases, the compression coefficient decreases, and the compression modulus increases. The vane strength has the power function correlation with water content, the linear positive correlation with compression modulus and fast shear cohesion. The specific penetration resistance of CPTU has the logarithmic correlation with water content, power function correlation with compression coefficient, and linear positive correlation with fast shear cohesion. The empirical formula can provide references for the construction of similar sites in the Pearl River Mouth area.