高速铁路多桩型硅藻土地基处理试验方案研究

Study on Experimental Scheme of Different Types of Pile Diatomite Foundation Treatment for High-speed Railway

为研究高速铁路硅藻土地基处理挤土桩与非挤土桩桩型的适应性及加固效果,依托新建杭绍台铁路硅藻土路基试验段,通过螺杆桩、CFG、钻孔灌注桩的施工工艺试验、桩基小应变测试试验、正常及浸水单桩静载荷试验,分析了非挤土桩与挤土桩的成桩过程、桩身质量完整性及加固效果;通过不同桩型的正常及浸水单桩复合地基激振试验,分析了非挤土桩与挤土桩的动响应特性及长期稳定性。通过上述试验,获得了硅藻土桩身侧摩阻力参数,浸水对硅藻土地基加固效果影响较小;验证了非挤土桩工法的适用性,由于挤土桩施工易造成硅藻土结构丧失且不能实现挤土效应,承载力无法满足设计值,且施工工效低不适用硅藻土地基处理,优选钻孔灌注桩加固方案。

In order to study the adaptability and reinforcement effect of extruded pile and non-extruded pile in the treatment of diatomite foundation for high-speed railway,based on the diatomite subgrade test section of the newly-built Hangshaotai railway,though the construction technology test,the small strain test of pile foundation and the static load test of normal and submerged single pile for screw piles,CFG and bored pile the pile-forming process,pile integrity quality and reinforcement effect of non-extruded pile and extruded pile were analyzed.Through the excitation test of normal and submerged single pile composite foundation of different types of pile,the dynamic response characteristics and long term stability of non-extruded pile and extruded pile were analyzed.The lateral friction resistance parameters of diatomite pile body were obtained via the above tests.The effect of diatomite foundation reinforcement is less affected by water immersion and the applicability of the non-extruded pile method is verified.Due to the loss of diatomite structure easily caused by the extruded pile construction and the earth-squeezing effect cannot be realized,the bearing capacity cannot meet the design value,and the low construction efficiency is not suitable for diatomite foundation treatment,so the reinforcement scheme of bored pile is preferred.