Dynamic Response Analysis And Experimental Research Of Concrete-filled Steel Tubular Piles Under Debris Flow

Debris flow is a common natural disaster in mountainous areas. in China, the southwest 、 the northwest and the North China have some mountainous areas are developing debris flow, the annual economic losses caused by debris flow and casualties are great. Debris flow in tremendous damages to pose a great threat to the regional ecological environment and social economy, causing serious damage to the mountains and valleys, and debris flow disaster in sediment can also change of cultivated land into desert sand beach. Therefore, it is of great significance to effectively control the debris flow in disaster reduction and prevention. According to the literature, The impact of large stone is the main cause of dam failure. However,the research on dynamic response characteristics of the dam under impact load is less.In this paper, three methods of numerical simulation, model test and theoretical analysis are taken to research on the dynamic performance and structural calculation methods of concrete-filled steel tubular piles under different impact loads. Then propose reasonable and effective measures for anti-impact. And the main work in this paper is as follows:(1) Nonlinear explicit dynamic program ANSYS/LS-DYNA was applied for numerical simulation. Simulation analysis of the concrete-filled steel tubular piles with both ends of unconstrained and constrained. The materials of steel and concrete are respectively applied to the Cowper-Symbols and Concrete-Damage constitutive model equations which are applicable to the impact load. The paper describes the analysis method of dynamic response of pile forest structure subjected to impact loads and put forward to the implementation of numerical model.(2) Taking two kinds of concrete-filled steel tubular piles with different constraints for research objects. By changing the energy of the impact, according to the structural stress characteristics, the dynamic response and failure mode of the structure under different impact energy were studied. The regularity of different impact height, impact mass and velocity parameters were studied, and the dynamic response was analyzed with the variation of the parameters, and the most unfavorable loading point was obtained.(3) Impact experiments of two kinds of models has been conducted. And the impact tests were carried out on a shock table designed by our team. Dynamic strain gauge, displacement sensor and acceleration sensor were used to monitor thetime-history response of the key members and nodes of structures. Comparion of the test results and the numerical simulation results was made to obtain the dynamic response of the concrete-filled steel tubular piles. The failure modes and the results of numerical simulation were verified.(4) The response of the concrete-filled steel tubular pile under impact the empty reservoir rocks, empty reservoir mud impact and full reservoir state is analyzed in detail, get the weak parts of the structure and the most unfavorable load condition for structure, and puts forward corresponding measures to strengthen.