颗粒迁移作用下宽级配土渗透性研究

Study of seepage in wide-grading soils with particles migration

宽级配土作为堆积层滑坡的主要物源,其渗透性研究是开展降雨型堆积层滑坡机制研究的前提和基础。宽级配土的渗透是一个包括水分运移和土体细颗粒迁移的复杂过程,但在研究其渗透性时通常只考虑了水分的运移而忽略了细颗粒的迁移。为此,采用自制大型渗透仪对3组不同D15/d85值(D15为粗粒组中小于该粒径的颗粒质量分数为15%的粒径;d85为细粒组中小于该粒径的颗粒质量分数为85%的粒径)的土样进行了饱和渗流试验,研究了宽级配土的水分运移特征和细颗粒迁移规律。研究结果表明:D15/d85值对宽级配土的渗透系数和细颗粒迁移有重要影响,D15/d85值越小,则土体渗透系数越小,细颗粒不易发生迁移;D15/d85值越大,渗透系数越大,试验过程中渗透系数变化越剧烈,迁出细颗粒的量也更大。根据渗透系数的变化也可判定土体内部细颗粒的运动情况,据此提出了3种宽级配土颗粒迁移模式。该研究成果加深了对宽级配土渗透特性的认识,为完善降雨型堆积层滑坡机制研究提供了新思路。

The study on the seepage in wide-grading soils,the main material of colluvial landslides,is the premise and foundation of the research on the mechanism of rainfall-induced colluvial landslides.The seepage in wide-grading soils is a complex process including the transport of water and fine particles.However,the migration of fine particles is usually ignored.Therefore,three soil samples with different D15/d85 (D15 is the particle size which 15%of the coarse-grained group by weight is finer than;d85 is the particle size which 85%of the fine-grained group by weight is finer than) were tested by self-made large-scale permeameter to study the transport of water and fine particles in wide-grading soils.The results show that the D15/d85 has a vital influence on the permeability coefficient and the migration of fine particles.The smaller permeability coefficient is,the more difficult migration of fine particles occur in soils of small D15/d85;the larger permeability coefficient is with the violent change,and significant fine particles movement observed in soils of large D15/d85.The change of permeability coefficient reflects the movement of fine particles in the soil,and three modes of particle migration are proposed for the wide-grading soils.The research improves the understanding of the permeability characteristics of wide-grading soils and provides a new mechanism of rainfall-induced colluvial landslides.