不同基础下夯实水泥土桩桩土应力比的试验研究

Experimental Study on Pile-soil Stress Ratio of Rammed Soil-cement Piles under Different Foundation

桩土应力比是一个非常重要而且难以准确确定的参数。该文通过对郑(州)西(安)客运专线上夯实水泥土桩复合地基进行的单桩复合地基的载荷试验和路堤下桩顶应力、桩间土应力的现场测试,分别获得刚性基础下和柔性基础下的桩顶应力、桩间土应力和桩土应力比,以及它们随荷载水平和加载时间的变化规律。探讨了两种不同基础下使得桩土应力比产生变化的不同内在机理。据此,提出了由载荷试验得到的桩土应力比不能直接作为柔性基础下的桩土应力比,而应该乘以一个折减系数。研究成果可为夯实水泥土桩复合地基的桩土应力比取值提供指导性意见。

The pile-soil stress ratio is an important parameter which is very difficult to determine accurately.By the load test of single-pile composite foundation and the field test of pile top stress,soil stress between piles under embankment on the rammed soil-cement pile composite foundation of Zhengzhou-Xi'an passenger dedicated line,pile top stress,soil stress between piles and pile-soil stress ratio under stiff foundation and flexible foundation,and their variation law with the loading level and the loading time are got.The different intrinsic mechanism which causes the pile soil stress ratio to change under two kind of different foundations is discussed.Accordingly,the article puts forward that the pile-soil stress ratio by load test should be multiplied by a discounting coefficient,when it is used as the pile-soil stress ratio under flexible foundation.The study results have directive significance to determination of pile-soil stress ratio value of rammed soil-cement pile composite foundation.