Analysis and Experimental Study on Bearing Behavior of Large Diameter Rock-socketed Pile in Moderately Weathered Cataclasite

This paper, based on the ultra-high engineering project in the coastal area of Shenzhen, conducts static load tests on three large diameter diameter rock-socketed piles and performs internal force tests using sliding micrometer method to analyze the bearing behavior characteristics of moderately weathered cataclasite rock-socketed pile. The results show that: (1) The load-settlement curve (Q-s) of the test piles is a gradual type, the unloading rebound rate is between 67%～80%, and the maximum settlement of the piles has not exceeded the limit value required by the code. The measured compression displacement of the pile is 18 mm-19 mm, the pile compression ratio is 45%～72% under the maximum test load, and the pile-soil force is still in the elastic-plastic stage. The actual pile top can bear a larger load, and the bearing layer of the site with cataclasite as the bearing layer is reliable. (2) The unit friction resistance of the embedded pile increases with the increase of the load during the loading process, and the friction resistance of each layer gradually comes into play from the top down. The maximum unit friction resistance gradually moves downward, and the maximum unit friction resistance is located in the moderately weathered cataclasite layer at the pile end. When the pile top load is 20,000 kN, the end resistance accounts for 12.1%～22.3%, and the lateral resistance of the rock and soil at the pile side bears a larger load transmitted from above. The end resistance has not been fully utilized, and there is a certain margin of safety in the design bearing behavior. (3) The measured value of the pile is about 1.2 times the calculated bearing behavior value, and the safety factor of the design bearing behavior is relatively high. The measured value of the rock-socketed pile end resistance is greater than the calculated bearing behavior value by about 50%, and the calculated value is conservative. The end resistance coefficient can be taken as a large value. In similar engineering design, the side resistance and end resistance coefficients of piles can be adjusted based on the measured results of test piles, and the design calculation values can be optimized.