格栅强度对桩-网复合地基桩-土应力比影响研究

摘要

This paper aims to explore the effects of different grille intensities to the variation of pile-soil stress ratio of pile-net composite foundations.On the basis of pile-net composite working mechanism foundation,it derives analytically the pile-soil stress ratio.Then it takes the net composite foundation of Ganlong(Ganzhou-Longyan) and Harbin-Dalian(Harbin-Dalian) high-speed rail piles as an engineering examples.It carries out a comparative analysis of the measured data from the pile under the grille strength 100kN· m-1 and 300kN· m-1 conditions to understand the pile-soil stress ratio variation.Finally it establishes a three-dimensional numerical model and further analyses the pile-soil stress ratio variation for the grid strength between 100kN· m-1～ 400kN·m-1.The results show that:as the grid strength increases from 100kN· m-1 to 300kN· m-1,the pile-soil stress ratio increased considerably.When the grid intensity exceeds 300kN· m-1,the pile-soil stress ratio increases to a lesser extent.By considering the characteristics of the greatest contribution composite foundation bearing,it is recommended to select the grid strength 200kN·m-1 ～300kN·m-1.Under this condition,the pile-soil stress ratio is from 3.8 to 4.5.%为探索不同格栅强度条件下桩-网复合地基桩-土应力比的变化规律,首先基于桩-网复合地基工作机理,推导出桩-土应力比的解析式;然后依托赣龙(赣州-龙岩)和哈大(哈尔滨-大连)高速铁路桩-网复合地基工程实例,由实测数据对比分析了格栅强度l00kN ·m-1和300kN·m-1条件下的桩-土应力比变化规律;最后建立三维数值模型,进一步分析了格栅强度在100～ 400kN·m-1区间的桩-土应力比变化规律.结果表明:格栅强度在100～ 300kN· m-1区间时,桩-土应力比随格栅强度增幅较大,当格栅强度超过300kN·m-1以后增加的幅度较小.考虑复合地基承载特性最大贡献,建议选取格栅强度200～300kN·m-1,此时桩-土应力比为3.8～4.5.