Experimental Study on Interface Characteristics of Open Caisson-Sand and Distribution Characteristics of Side Friction Resistance
The side friction resistance of the open caisson is a key concern in bridge engineering.In order to study the interface characteristics of open caisson-sand,a large direct shear apparatus was used to conduct interface shear tests on different types of sand under different normal stress and moisture content conditions,and model tests were conducted to study the distribution characteristics of side friction resistance during the sinking process of open caisson under different types of sand,with or without steps,and different construction conditions.The results shows that the shear stress of the open caisson-sand interface increases with the increase of the shear displacement while the shear displacement is small.When the shear displacement reaches a critical value,the shear stress tends to stabilize.The interface shear strength decreases slightly with the increase of water content.The interface shear strength parameter is mainly based on the friction angle,and the cohesion is small.The interface water sensitivity is low.During the sinking process of the caisson,the curve between the soil pressure of the side wall and the depth occurs an"inward turn"at the cutting curb of the caisson,meaning that the soil pressure of the side wall undergoes stress relaxation at the cutting curb of the caisson.The degree of stress relaxation is positively correlated with the depth of sinking,and decreases with the increase of sand particle size.Compared with non stepped caissons,the soil pressure on the side walls of stepped caissons is significantly reduced.Setting step one the caisson can significantly reduce the difficulty of caisson sinking.Filling sand between the stepped caisson and the soil results a small increase in soil pressure on the side wall,which has little impact on the difficulty of caisson sinking.
万方数据
维普
