基于原位测试的黄土物理力学参数演化分析

Evolution analysis of physical and mechanical parameters of loess based on in-situ test

为研究外荷载、地下水等多因素长期联合作用下黄土地基土参数的演化规律,依据原位钻探、标准贯入试验和室内土工试验等手段,结合历史勘查资料,对近30 a来渭北某黄土地基土的含水率、干密度、饱和度、孔隙比、湿陷系数等物理力学参数的演化规律进行总结,同时,依据数理统计方法对黄土物理力学参数演化影响因素的敏感性进行了分析。结果表明:长期荷载作用下黄土的干密度随时间增加总体呈现增加的趋势;受附加荷载直接影响的浅层地基土体的孔隙比减少幅度较大,而深层土体的孔隙比影响较小;土体的饱和度随着深度的增加总体呈现“增→减→增→减”的周期性;相较于附加应力的长期作用,黄土的直立性和湿陷性工程性质对土的压缩特性影响更大。该研究为黄土地区地基土强度和变形参数的研究提供借鉴。

In order to recognize the evolution laws of the soil parameters of loess foundation under Multi-factor&Long-term&Combined effect such as external load,groundwater,et al,according to the methods of in situ drilling,standard penetration test,laboratory soil test and historical survey material,we summarize the evolution laws of physical and mechanical parameters such as water content,dry density,saturation,pore ratio and collapsibility coefficient of a loess foundation soil in Weibei in recent 30 a.Meanwhile,we analyze the sensitivity of factors affecting the evolution of loess physical and mechanical parameters based on the mathematical statistics.The results show that the dry density of loess under the long-term load increasing with time.The void ratio of shallow-layer soil which is directly affected by additional load decreases greatly,while the void ratio of deep-layer is little affected.With the increase of soil depth,the saturation of soil generally presents the periodic property of"increase→decrease→increase→decrease".Compared with the long-term effect of additional stress,the vertical and collapsible engineering properties of loess have greater influence on the compression properties of soil.This study provides a reference for the study of strength and deformation parameters of foundation soil in loess area.