Research on the control of high-fill roadbed with tunnel slag in karst sections

Abstract

In this study, 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 was used to manage the substructure of the karst section. After installing prestress anchors on the top of the foundation, a ‘layered’ filling scheme was utilised to fill the tunnel slag and clayey gravel. The Flac3D simulation software was used to contrast the deformation curves of key nodes on unanchored and anchored roadbeds. The test results indicate that the California bearing ratio 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 within 94%. The use of prestress anchors can strengthen the rock and soil layers of the foundation and reduce the plastic zone distribution. This paper provides a corresponding engineering experience for the treatment of high-fill roadbeds in karst areas.