关键词: 长短桩组合路堤桩, 三维复合拱, 桩-土应力比

Abstract: Based on the Hewlett method for analyzing composite embankment with equal length piles, a three-dimensional hybrid soil arching analysis method is developed to explore the load sharing ratio of composite embankment with long and short piles under uniform pressure. The basic theoretical framework of three-dimensional hybrid arching analysis is established based on the vivid description of the stress concentration obtained from the finite element analysis. The soil arching effect coefficient is adopted to feature the incremental generation and the progressive failure of the arches, which changes with the increase of the length ratio. The equilibrium differential equation on the pile caps is established. The stress concentration ratios of the long piles and the short ones are calculated through solving system of equations including the equilibrium differential equation, boundary condition equation and relational expression of the two different soil arching effect coefficients. When the geosynthetics is taken into account, the reinforcement tension is calculated through the assumed deformed curves. And then a new equilibrium differential equation over the elevation of the pile caps is generated. Eventually, the results of centrifuge tests, in-situ tests and the finite element method are compared with those from the analytical method and are found to be in good agreement. Furthermore, parameter analysis is performed to evaluate the main influence factors on the soil arching. The analysis shows that the pile-soil stress ratio of the composite embankment with geosynthetics is significantly larger than that of the embankment without geosynthetics, especially when the cap coverage rate is relatively small.

Key words: composite embankment with long and short piles, three-dimensional hybrid soil arching, pile-soil stress ratio