大厚度自重湿陷性黄土场地现场浸水试验研究

Study on Field Immersion Test of Large Thickness Self-weight Collapsible Loess Sites

针对大厚度自重湿陷性黄土场地工程建设中所面临的湿陷性评价及地基处理等技术难题,通过现场试坑浸水试验手段,研究了试验过程中注水量的变化规律、水分场的运移规律、地表及深部湿陷变形特征、周边裂缝发展特征、浸水影响范围及饱和范围、地基土渗透系数、自重湿陷下限深度及其确定标准;在此基础上,提出一种考虑地层沉积时代反算因地区土质而异的修正系数β的方法,并对黄土自重湿陷的判别标准进行了初步探讨,结果表明,Q黄土采用0.015的判别标准较为合适,Q黄土采用相同标准不太合适,对于Q黄土的自重湿陷性的评价建议采用现场试坑浸水试验确定。研究成果可为地区工程建设提供参考及借鉴。

To solve the problems of collapsibility evaluation and foundation treatment in construction of large thickness selfweight collapsible loess sites, field immersion test was conducted. The rule of water injection rate, the movement of moisture field, the collapse characteristics of surface and underground, the development characteristics of cracks around the test pit, the influence range of both immersion and saturation, the permeability coefficient of foundation soil, the lower limit depth of self-weight collapsible loess and criteria were studied. On this basis, a method is proposed to calculate the correction coefficient βwhich varies with the soil quality in different areas by considering the sedimentary age of the strata. A preliminary discussion on criteria of self-weight collapse of loess has been conducted. The result is: 0.015 is appropriate for Qloess but not for Q. It is suggested that field immersion test should be conducted to evaluate self-weight collapse of Qloess. The research results can provide reference for regional engineering construction.