Treatment Technology and Design Plans for Expansive Soil Subgrade of Nanning Outer Ring Expressway

摘要

The proposed Nanning outer ring expressway crosses expansive soil distribution area. Cut slopes treated by rigid retaining are mostly unstable, and adopting filling plan to replace excavated expansive soil with non-expansive soil will both increase the construction cost and damage the ecological environment. Therefore, new treatment technology needs to be studied. The feasibility of using expansive soil treated by physical treatment technique to directly build the embankment is demonstrated through a series of tests on soil properties and filler quality, and the stability of expansive soil cut slope treated by flexible supporting was analyzed. Based on the tests, the theoretical analysis, and successful treatment experiences, two measures with the characteristics of "enveloping and wrapping" for expansive soil embankment and for design of flexible supporting for expansive soil cut slope are put forward. They provided the basis for rational use of Nanning expansive soil and construction of expressway with a low-carbon and environmental mode.