降雨及蒸发条件下地裂缝研究

工程中所遇到的土体大多数以非饱和土形态存在。以海南地区的特殊土红粘土为研究对象,在对其进行土—水特性研究的基础上,认为Van Genuchten模型较好地反映了海南红粘土饱和度与基质吸力的关系。结合Bishop提出的非饱和土的有效应力表达式,分析了降雨及蒸发下地裂缝的发展机制。通过数值算例发现,在非饱和土中,静止土压力系数不再保持不变,而是随着深度和稳定流流量的变化而变化,与饱和土中的静止土压力系数的性质有很大不同,这在工程实际中对支挡结构的设计具有重要的指导意义;在非饱和土中,由于静止土压力系数存在负值,容易产生地裂缝,且在蒸发条件下,最大地裂缝深度理论上比在无渗流和降雨条件下的大。

Study on Ground Fissure under Rainfall and Evaporation

Most of the soil encountered in engineering exists in the form of unsaturated soil. Tak- ing the special red clay in Hainan area as the research object, based on research into the proper- ties of soil and water of the red clay, it is considered that Van Genucbten model reflects better the relationship between saturation and base material of red clay in Hainan. Combined with the ex- pressions of the effective stress of unsaturated soil proposed by Bishop, the development mecha- nism of swell-shrink ground fissure under rainfall and evaporation was analyzed. Numerical ex- ample shows that for unsaturated soil, the coefficient of at rest earth pressure is not a constant, but varies with the depth and steady flow, which is different from that in saturated soil. In prac- tice it has an important guiding significance for the supporting structure design. At the same time, because the coefficient of earth pressure at rest has negative values in unsaturated soil, swell-shrink ground fissure is prone to produce. And in the evaporation condition, theoretical maximum ground fissure depth is greater than that in the absence of ground seepage and rainfall conditions.