Highway Subgrade Construction in Expansive Soil Areas

Abstract

Engineering problems with expansive soils in subgrades complicate highway construction in expansive soil areas of China. To research and solve the engineering problems, a Chinese research group carried out extensive research as part of the construction of a highway in Ningming Basin, a typical expansive soil area in China. The research on Ningming expansive soils is presented, including laboratory studies of soil properties, modified California bearing ratio tests for evaluating the bearing capacity, and wet compaction tests for obtaining the parameters to control field compaction when using expansive soils as embankment fill. The field investigations of slope failures also are introduced, including analysis of the investigations. New techniques for using expansive soils in embankments, and stabilizing cut slopes consisting of expansive soils, were developed and applied into the trial sections of the highway by the research group, based on their research and investigations. The measures proved successful and were used to solve the technical problems related to the NanYou Highway subgrade construction. The outcomes of the research also may prove useful in the construction of such projects as railway and hydraulic works.