Settlement control investigation of high fill subgrade in karst section with tunnel slag filling

Abstract

In this paper, based on the Kaihua section of the G205 (China) national highway reconstruction project, the construction area of the K4+550-K4+940 section was chosen to conduct settlement control research on the high-fill roadbed of the karst section within the construction area. The viability of using clayey gravel and tunnel slag as roadbed fill was evaluated through laboratory soil tests. The construction technology of grouting is used to manage the substructure of the karst section. After installing pre-stress anchors on the top of the foundation, a “layered” filling scheme was utilized to fill the tunnel slag and clayey gravel. The FLAC3D simulation software contrasted the deformation curves of key nodes on unanchored and anchored roadbeds. The test results indicate that the California Bearing Ratio test (CBR) test satisfies the requirements of the specification and that the uniaxial compression strength of the tunnel slag satisfies the requirements of the specification when the clayey gravel is near the optimal moisture content and dry density, and when the compaction is controlled to within 94%. The use of pre-stress anchors can strengthen the foundation’s rock and soil layers, and reduce the plastic zone’s distribution. This article provides a corresponding engineering experience for the treatment of high-fill roadbeds in karst areas.