Study On Bearing Performance Of Anchorage Foundation Of Underground Diaphragm Wall

Relying on Humen Second Bridge,combined with the engineering test data,the excavation,the bearing behavior and the stability of anchorage are analyzed by numerical simulation.The main research contents and conclusions are as follows:First,in order to study the change law of the bearing behavior of underground diaphragm wall of anchorage at different excavation depth,the excavation process is simulated by the finite element model.By comparing measured values and simulated values of radial displacement,earth pressure and vertical strain of underground diaphragm wall of the west anchorage,the validity of model is confirmed.Then,the change law of the radial displacement of underground diaphragm wall and earth pressure of the east anchorage at different excavation depth is studied by simulating the excavation.The results show that as the excavation depth increases,the maximum radial displacement position of underground diaphragm wall moves parabolically to 15 meters depth and almost keeps the same.The maximum radial displacement of underground diaphragm wall is 14.1 millieters.The maximum earth pressure in the soil layer is at-24 m,with the increase of the excavation depth,the maximum is up to 430 kPa.Second,before and after cable force,the radial displacement,horizontal shear force,axial force and bending moment of east anchorage of Humen Second Bridge are analyzed.By changing structural parameters of anchorage and geological conditions,the change law of the bearing performance of anchorage is studied.The results show that the maximum horizontal displacement of anchorage is-1.6mm and 9.05 mm respectively.After the cable force is applied,the maximum shear and bending moment of the diaphragm wall are 100 MN and 9135 MN·m respectively.On the most unfavorable section of the anchorage,the most influential factor of the internal force ratio of underground diaphragm wall and anchorage is the thickness of the diaphragm wall,followed by the rock socketed depth and the elastic modulus of the rock layer,and the influence of the upper and lower plate thickness and the external friction angle on the internal force ratio is relatively small.The elastic modulus of the rock layer is the most influential to the horizontal displacement of the anchorage,followed by the depth of the rock socketed.Finally,based on the standard calculation,the stability of the east anchorage of Humen Second Bridge meets the requirements and is compared with other bridge projects’ in China.Based on the equal proportion increase of cable force method and the displacement control,the influence of the structural parameters of anchorage and geological conditions on the stability of anchorage foundation is analyzed.The results show that the greatest influence on the safety factor of anchorage is the elastic modulus of the rock layer,followed by the depth of rock socketed and the thickness of the wall.The upper and lower plate thickness and the external friction angle have the least influence on the safety factor of the anchorage.