水泥土桩与土工格栅联合加固沟谷软基机理研究

针对山区沟谷软基的特殊土质,并结合夯实水泥土桩和土工格栅在地基加固中的作用特点,提出用夯实水泥土桩与土工格栅联合加固的方案来处理沟谷软基,并利用平面应变弹塑性有限元数值分析方法,对这种地基的受力性状、作用机理进行了多方面研究。结果显示:土工格栅在其中起到类似抗拉膜的作用,以控制地基的不均匀沉降,可以减小路堤坡脚附近的侧向位移,增加地基的极限承载能力。桩间土对夯实水泥土桩有负摩擦力作用,使得桩身的最大平均有效应力位置处在桩体的中下部。格栅对路基沉降量的影响则较小。

Study on geogrid-reinforced and pile-supported embankment over gulch weak subsoil

The popular and traditional method of foundation treatment in mountainous areas is to adopt the system of piles. But in some conditions such as existence of the thick mud layer, it is not perfect to use the pile group solely. This paper presents a new combinational foundation system, using geogrids and compacted soil-cement piles to improve the weak subsoil in the mountainous areas. Through the plane strain finite element method, the behavior and mechanism of improved embankment are studied and some useful functions of the geogrid are found in the composite subsoil. For example, the geogrid behaves like a tensioned membrane. It can significantly reduce the differential settlement between the pile head and the surrounding soil and side displacement of the embankment. With the help of the geogrid, the limit bearing capacity of the subsoil is promoted considerably. It has been found that the geogrid has less influence on the embankment settlement. In addition, the largest effective stress appears near the bottom of the piles due to the negative surface friction existing between the soil-cement piles and the subsoil.