Experimental study on capillary water rise and influencing factors in silty soil

Silty soil has characteristics of capillary pore development and strong water sensitivity. The rise of capillary water in silty soil may induce the strength reduction or instability of subgrade. Therefore, it is of great significance to clarify the law of capillary rise in silty soil. In this paper, based on the indoor model test of capillary rising height, the effects of compaction degree and initial moisture content on the capillary water rising characteristics of two different soils (silt and silty sand) were investigated. The results show that the faster the rising speed of capillary water in the early stage, the faster the attenuation speed in the later stage and the lower the final rising height. When the initial water content was the same, the rising height of capillary water increased with the increase of compaction degree, but its increasing range decreased gradually. Keeping the degree compaction unchanged, the rising height of capillary water decreased with the increase of moisture content. The more the fine particles content and the better the grading, the higher the capillary water rise in the silt. Furthermore, according to the test results, the relationship between the rising height of capillary water in silt and time was highly consistent with the quadratic polynomial in double logarithmic coordinates. The rise of capillary water was harmful only in a certain range of height. The results indicate that the dangerous heights of capillary water rise of the silt and silty sand in Nantong area were between 150~180 cm and 140~170 cm, respectively.