Study on the settlement characteristics and reinforcement technology of unsaturated soil ground of high-speed railway

The restricting of post-construction settlement of railway subgrade is a key technology to designing and constructing high-speed railway. The consolidation settlement of unsaturated soil ground is more than saturated soil, so it is difficult to control post-construction and plan construction period. In this article, author monitors the variance of settlement of the typical unsaturated silty clay or silt ground in Jiaozhou peninsula and northern China, analyses the settlement law of unsaturated soil ground, and examines reinforcement effects on ground by the use of dynamic compaction and soil-cement pile. The outcome of experiment shows that, the settlement of the shallow ground within the depth of six metres is more than sixty percent of the whole for the unsaturated silt or silty clay ground. Having been reinforced by dynamic compaction and soil-cement pile, the unsaturated soil ground meets the design requirement of high-speed railway subgrade. Comparing to dynamic compaction, the settlement of unsaturated subsoil reinforced with soil-cement pile decreased, and the consolidation settlement velocity sped up. It is therefore beneficial to control the post-construction settlement of unsaturated silty clay or silt soil ground by soil-cement pile. It should be given priority to adopt this reinforcement measure in engineering practice.