黄土湿陷典型案例及相关问题

Typical case study of loess collapse and discussion on related problems

黄土湿陷除引发路基变形、房屋开裂等工程建设问题外,还会造成地表塌陷、地下潜蚀,以及由此诱发的黄土斜坡失稳等灾害。通过对甘肃永靖县黑方台灌区典型黄土湿陷案例的分析发现,应用现行规范推荐方法对黄土湿陷量进行评价,其计算值与实际观测值间具有较大差距,计算值不足实际值的50%。由此,对现行黄土湿陷性评价中的湿陷性黄土定义、湿陷量计算等有关问题进行讨论,认为湿陷性黄土为典型的非饱和土,含水量和结构组成是影响黄土湿陷的重要因素。从非饱和土力学角度出发,应用综合反映黄土含水量和结构的参数,即吸应力,开展黄土湿陷性研究,才能真正地实现由"为什么湿陷"到"怎么湿陷"的转变,进而建立黄土湿陷的本构关系,更好地服务于工程实践。

Collapsibility is the unique feature of loess. Problems induced by collapse of loess include deformation of foundation, subsurface erosion, and slope failure. A case study of loess collapse at Heifangtai of Yongjing County in Gansu Province was analyzed in this paper. There exists a notable difference between the calculated result with the recommended equation in the national standard and the real collapse value. The calculated value of collapse is less than 50% of the motivated data. The definition of collapsible loess, the calculation method and the related issues on the assessment of loess collapse were discussed, and the results show that collapsible loess is typical unsaturated loess, and water content and structure are key factors affecting collapsibility of loess. Only by adopting the theory of mechanics of unsaturated soil and employing the parameter representing both the water content and the structure can the research on loess collapse realize the change from ＂why collapse＂ to ＂how collapse＂ so as to achieve the purpose of better serving engineering construction.