高速铁路中低压缩性土桩-筏(网)地基加固效果研究  

Research on reinforce effect of high-speed railway low and medium compressible soil pile-raft(net) foundation

作　　者：左珅[1] 王敏[1] 徐林荣[1] 朱华鹏[1] 

机构地区：[1]中南大学土木工程学院,湖南长沙410075

出　　处：《中南大学学报（自然科学版）》2014年第5期1590-1597,共8页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51078358);高铁联合基金资助项目(U1134207);铁道部科技研究开发计划项目(2012G009-C)

摘　　要：基于沪宁(上海—南京)城际铁路CFG桩-筏地基(预压期超短,4月)和京沪高铁砂桩-网地基(昆山试验段预压期超长,间隔5 a)现场试验,测试获取路基沉降变形、孔压消散、桩土压力分布变化等规律,对比分析桩筏与桩网地基工作性状差异。研究结果表明:桩-筏和桩-网地基联合堆载预压可以满足中低压缩性土高铁无砟轨道工后沉降控制要求,桩-筏地基沉降总量与沉降速率均小于桩-网地基的沉降总量与沉降速率,堆载预压时间可以弥补地基加固结构的不足;受桩体刚度影响,CFG桩-筏桩体荷载分担比大于砂桩桩-网地基的荷载分担比,其超孔压消散速率则远比后者的小;筏板具有类似拱的传荷作用,板下应力分布较均匀,桩网路基基底压力分布呈倒钟型;在工期紧张情况下,桩筏地基工后沉降控制效果比桩网地基的控制效果优,但前者造价较高,高铁地基加固技术选择时需考虑综合效益。Based on the test section of Shanghai--Nanjing intercity railway CFG pile-raft foundation （preloading period is exceeding short, 4 months） and Beijing--Shanghai high-speed railway sand pile-net foundation （Kunshan embankment preloading period is exceeding long, 5 years）, the change law of subgrade settlement deformation, pore pressure dissipation, pile soil stress distribution were tested, and work character of pile raft and net foundation was comparatively analysised. The results show that pile-raft and pile-net foundation with preloading can control low and medium compressible soil post-construction settlement of high-speed railway unballast track. The velocity of settlement of pile-raft foundation settlement is higher than that of pile-net foundation, but preloading time can make up for the inadequacy of foundation reinforcement structure. Affected by the pile stiffness, the pile load sharing ratio of CFG pile-raft is greater than that of sand pile-net foundation, and excess pore pressure dissipation rate is far less than the latter. Raft has the load transfer function which is similar to arch, so the stress distribution under raft is uniform, the pressure distribution of pile-net subgrade like a revers clock. Considering nervous construction period, pile-raft foundation has better post-construction settlement control effect, but the cost is higher, when choosing foundation reinforcement technology, the comprehensive benefit should be considered.

关 键 词：桩-筏(网)复合地基 中低压缩性土 工后沉降控制 

分 类 号：TU443[建筑科学—岩土工程]