Anti-earthquake Mechanism And Sensitivity Analysis Of Design Parameters Of Pervious Concrete Pile Composite Foundation

In the past20years, foundation treatment technology has been developed greatly, and the composite foundation becomes the most widely used. Vertical reinforcement in composite foundation generally can be divided into granular material pile, flexible pile and rigid pile. The granular material pile, such as stone columns, is permeable, which can effectively drain off water and accelerate the rate of consolidation of the foundation, and then reduce the liquefaction potential. But its stiffness and strength are low, and they are dependent on the confining pressure of soil around the pile, as a result, the shallow pile is prone to occurring expansion damage. And when the granular material piles are used in soft clay foundation, bearing capacity can hardly be improved and the post-construction settlement is great. In contrast, the rigid pile composite foundation, such as CFG pile, can meet the requirements of strength and deformation, but cannot effectively drain off water and the consolidation speed is slow due to the poor permeability, leading to little resistance to liquefaction. This paper intends to apply the pervious concrete to the design of composite foundation, and pervious concrete pile composite foundation with both quick drainage and high load performance is put forward.Based on the laboratory experiments and numerical simulation, the material performance of pervious concrete, the anti-earthquake mechanism and sensitivity analysis of design parameters of pervious concrete pile composite foundation are studied. The main contents are as follows:First, based on the design theory of pervious concrete, the specific mix design method is put forward by indoor experimental study. Meanwhile, the effects of different design parameters (such as water-cement ratio, porosity, aggregate-cement ratio, etc.) on the mechanical properties and water permeability of pervious concrete are studied. And the growth models of compressive strength and tensile strength and porosity-permeability model are established.Numerical liquefaction experiments were conducted using three-dimensional finite-difference software, separately on natural liquefiable sand foundation and the foundation respectively reinforced by plain concrete piles(CP), stone columns(SC) and pervious concrete piles(PCP). The liquefaction distributed characteristics of natural foundation and different pile composite foundation were studied. The anti-liquefaction effect of the pervious concrete piles was selectively investigated, and the dynamic characteristic of the foundation after imposition of pervious concrete piles was analyzed.Sensitivity analysis of design parameters (pile diameter, pile spacing, replacement rate, permeability coefficient, modulus, and external acceleration amplitude) of pervious concrete pile composite foundation was studied.The pervious concrete piles have the advantages of both the granular material piles and rigid piles, and they have broad application prospects in the field of anti-liquefaction foundation. This thesis provides an important reference for it is an engineering innovation.