Centrifugal test on vertical load bearing characteristic of pile foundation crossing karst cave in steep sloping area
Centrifugal model tests were used to analyze the effects of cave height changes when the foundation slope is certain under the vertical load at the pile top on the load-settlement curve of the pile foundation,the ultimate bearing capacity of the pile foundation,the pile axial force and the pile side resistance in order to analyze the vertical bearing characteristics of bridge pile foundations crossing the karst cave in the steep slope area. The key parameters affecting the vertical bearing characteristics of the pile foundation were given. Results show that the vertical ultimate bearing capacity of pile foundation decreases with the increase of karst cave height,and the decrease of ultimate bearing capacity increases with the increase of karst cave height under a certain pile length and total depth of the pile foundation into the rock. The decrease of ultimate bearing capacity is not obvious when the karst cave height is less than 1.2 times the pile diameter. The decrease of ultimate bearing capacity increases significantly when the karst cave height is larger than 2.4 times the pile diameter. The decay rate of pile axial force is slower in the pulverised clay layer,faster in the bearing stratum,and does not decay in the range of the karst cave. The decay rate of axial force in the range of the bearing stratum increases significantly after the karst cave height is larger than 2.4 times the pile diameter. The pile side resistance in the holding layer is significantly larger than that in the upper rock and soil layers,and zero in the karst cave. The proportion of pile side resistance in the vertical ultimate bearing capacity of pile foundation gradually decreases as the karst cave height increases. The pile side resistance is reduced by 65.5％ when the cave height is larger than 2.4 times the pile diameter,and the pile foundation is gradually transformed from a friction pile to an end-bearing pile.
万方数据
