Lateral Bearing Characteristics Of Rock-socketed Pile In Weathered Jointed Granite

Rock-socketed piles are commonly used in offshore structures such as offshore wind turbines and bridges,but the research about the interaction of piles and weathered rock and lateral bearing characteristics of pile embedded in weathered rock remains inadequate.The influence of rock joints on the lateral bearing characteristics of rock-socketed piles is not clear.Therefore,it is necessary to study the lateral bearing characteristics of pile embedded in weathered rock and develop a reasonable approach for the analysis of the bearing characteristics of lateral loaded rocksocketed pile to optimize the design of pile foundation.Based on field test data,the existing methods for analyzing the lateral bearing characteristics of pile foundation are compared.The results show that although m method and constant method satisfy the requirements of the engineering project,a reasonable calculation method to determine the parameters for weathered rock mass has not been proposed.The numerical models of rock socketed piles are constructed using finite difference software to carry out a numerical parametric analysis taking account various factors that influence the rock-pile interaction such as mechanics parameters of rock and pile.A calculation formula is developed to determine the proportional coefficient of the subgrade modulus in the m method.According to the mechanical characteristics of the rigid pile,considering the effect of vertical skin friction,a calculation method to determining the response of rigid pile under lateral load is proposed based on the assumption of constant method.The calculation results are more accurate compared with the results without considering vertical skin friction.The fitting formula of the subgrade modulus for constant method is also proposed by numerical parametric analysis.The method proposed in this paper is verified by fullscale lateral load test data,and the computed pile responses are in good agreement with the actual situation.The numerical models of rock-socketed piles embedded in rock mass with one set of parallel joints and three sets of orthogonal joints are established using discrete element software to study the influence of the weather joints on the lateral bearing characteristics of piles.The formula to calculating the initial stiffness of p-y curve is proposed according to the hyperbolic model.Based on the research of the distribution of stress in rock mass with stratified structure and blocky structure and the wedge failure model,the calculation methods of the ultimate resistance of rock mass are also developed.Compared with the theories based on the isotropic continuum models,the methods proposed in this paper consider the anisotropic characteristics of rock mass and reflect the actual situation of pile-rock interaction.The responds of rock-socketed piles under different conditions computed using proposed methods also agree well with the numerical simulation results.Finally,based on the actual situation of Fujian Pingtan offshore wind power project,after determining the weathered rock parameters,and the p-y curve and the responses of the pile foundation under design loads are calculated by using the methods proposed in this paper,which can contribute to the reasonable design of laterally loaded rock-socketed pile.