Experimental study on settling characteristics of thick self-weight collapsible loess in Xinjiang Ili region in China using field immersion test

Abstract

To study the settling characteristics of Ili loess, a field immersion test was implemented on thick collapsible loess with seepage holes to speed up the collapse. The loess at the test site belongs to the Q3eol stratum and had a thickness of 30 m. The on-site settlement, the degree of saturation, and other observations, such as surface cracks and dolinas, were continuously monitored. The experimental results show that Ili loess is a typically collapsible eolian soil with a large thickness, strong water sensitivity, low anti-erosion capability, and strong self-weight collapsibility. The collapsibility of the Ili loess was basically eliminated by the field immersion test. One primary reason was the significant reduction in the numerous trellis pores. In comparison with other similar tests, a much higher settling rate and self-weight collapsible settlement were observed. The correction coefficient of collapsibility for Ili loess is 1.64, which is calculated as the measured self-weight collapsible settlement divided by the calculated value. It is a key parameter for evaluating the loess collapsibility in the area. A four-stage settling trend was characterized; it is distinguishable from other regular five-stage models. It was confirmed that the pre-immersion method with seepage holes is an effective method of foundation treatment for the Ili loess region.