CFG桩桩板复合地基处理高速铁路地基的现场试验研究

通过对地基的分层沉降、超孔压、侧向变形及土压力现场测试,研究了CFG桩在桩顶和筏板之间设置15 cm厚碎石褥垫层进行高速铁路路基深厚松软土地基工后沉降控制的地基受力、变形规律。测试结果表明桩间土的压缩发生在桩长下部的一定范围之内;摩擦桩桩端会产生进入下卧层的刺入沉降;没有连通有效排水通道的深层透镜体砂层中的超孔压消散规律与邻近的黏土层是一致的,不能作为透水层;桩向下刺入下卧层,桩端附近的土体中产生较高的超孔压,在深层没有排水面时,此超孔压会向浅层的地层消散,从而会引起浅层地基土的超孔压也经历一个先增长后消散的变化过程。地基的侧向变形微乎其微及桩土应力比都表明这样的结构很类似桩基础。

Field Test Study on CFG Pile-slab Composite Ground in High-speed Railway

Mechanics rule of thick soft ground treated by CFG pile-slab composite ground, where a gravel mat of 15 cm thickness is set between the top of the pile and the slab, for post-construction settlement controlling in high speed railway subgrade is studied through in situ inspection of layered settlement, excessive pore pressure, lateral deformation and soil pressure. The results show that the compression of the soil among piles occurs in the certain range of the lower part of the pile. Friction pile will result in penetration settlement into the underlying layer. The dissipating course of excess pore pres- sure of the deep lenticels sand layer without connecting to a valid drainage way consists with that of the clay layer next to it, so lenticels sand layer can not be considered as permeable layer. The downward penetration of the pile into the underlying layer causes relative high level excess pore pressure of the soil near the tip of the pile, which will dissipate to the superficial layer in case there is no deep dissipating face, and causes the excess pore pressure of the superficial layer soil to go through a course of increasing and then dissipating. Both the tiny lateral deformation and the ratio of the pressure of the pile and the soil demonstrate that the structure is similar to pile foundation.