Multilayer Karst Areas Deep Water Of Large Diameter Pile Bearing Behavior Analysis

Along with the implement of west development strategy of China, lots of expressways being built or to be built will inevitably pass through karst areas, and the complicated karst condition will bring difficulties for building bridge pile foundation. Furthermore, in karst areas the pile foundation design and building using the existing specifications are difficult to meet demand. Therefore, based on present research results of large diameter piles and starting from the karst areas impact on bearing capacity of pile foundation, combined with the subject of "Study on the large diameter of deep water piles foundation design and construction control technology in karst areas", through the field test and numerical simulation expansion study.The researches have been done as follows:Firstly,for particularities of large-diameter pile foundation in karst area, on the basis of summing up the results, analysis of large diameter pile foundation under vertical load bearing capacity characteristics in karst area, large-diameter rock-socketed piles in karst area and calculation method of pile end bearing capacity and failure modes are summarized.Secondly,finite element model is developed. The elasto-plasticity of concrete is considered, and Drucker-Prager model is applied in pile foundation and rock mass with contact surface between pile and rock. Considering initial stress and analysis of bearing behavior of large diameter pile foundation in karst areas.Thirdly,the monitoring data for large diameter piles foundation in karst areas is processed, and the actual monitoring data of pile shaft force, side friction of pile, and the analysis result of finite element are analyzed in comparison.The last,by using this model, the influencing factors such as Radius of caves, Cave roof thickness, Cave heights, Elastic modulus of rock and pile which have effect on the bearing capacity of the pile are studied.