ABAQUS6.10 is applied to analyze the stability and ultimate bearing capacity of karst cave roof under the loading of pile foundation. Physical and mechanical indexes of rock mass are estimated by Hoek-Brown strength criterion and nonlinear elasto-plastic model is adopted in the finite element analysis for ultimate bearing capacity of cave roof. The ultimate bearing capacities under different conditions of GSI of rock mass, karst cave sizes and different roof thickness are obtained based on the

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... etermination of the ultimate bearing capacity of cave roof under the loading of pile foundation. The correlations between the ultimate bearing capacity and the corresponding influencing factors are obtained by utilizing the least square method to fit the calculated data. The variations of the ultimate bearing capacity are presented by analyzing the correlations. The results show that the ultimate bearing capacity decreases with increasing of the width of karst cave and increase with increasing of GSI of rock mass and roof thickness. The relations among the ultimate bearing capacity, the width of cave, the roof thickness and GSI of rock mass can be obtained by means of multiple linear regression method. The results of significance tests and analysis of variance show that the linear relationships between the variables are highly significant and the regression equations are reliable. In the end, the analysis of the practical engineering project proves the feasibility and the rationality of the regression equation which can be a new method to calculate the ultimate bearing capacity of cave roof under the loading of pile foundation.