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This thesis mainly relys on a project in Foshan, the specific practice of the karst area pile foundation investigation, design and risks of geological exploration, evaluation, processing and testing techniques such as complete a comprehensive study.Firstly, in this pater, the development and characteristics of karst along the project were summarized and discussed. And then describding the comprehensive survey techniques of the karst area combining the drilling and geophysical techniques, focusing on the tube-wave detection method and CT scan of cross-hole,two kinds of geophysical methods have been studied and the results of verification, the survey summed up the principle of karst areas.Secondly, quantitative and qualitative analysis has been taken to evaluate the the impact of geological risks of the pile bearing stratum, and then verified by the concrete examples.Thirdly, the geological risks of the the pile bearing stratum are classified, and the corresponding treatment solution are put forward, combining with some engineering examples, the method of reinforcement and testing for the different geological risks of the pile foundation are introduced.Finally,in this paper the finite element model for pile foundation with the the mutil-level tall cavity is established,according to the existing data and based on the study for boundary conditions physical parameters of the karst area .And then,the finite element analysis for the stress distribution of the pile foundation in the karst area is done,which helps to the research of the impact of the geological strength, pile diameter, pile length and other factors on the stability of the cave roof.
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