ANALYSIS OF THE CAUSES OF DEFORMATION AND FAILURE OF TRACTION-TYPE SLOPES: A CASE STUDY OF SLOPE ON TIANXI HIGHWAY IN GUANGXI, CHINA

Abstract

Slope deformation poses a severe challenge to highway construction. To explore the failure mechanism of typical traction-type deformation slopes, this study systematically evaluated the deformation mechanism of the right slope of the K170+080~K170+260 section of the Guangxi Tianlin to Xilin Highway (referred to as Tianxi Highway) based on field survey and monitoring data, combined with the finite element software PLAXIS 2D. The results show that the sliding zone of the slope is buried at a depth of about 16 m, mainly composed of strongly weathered sandstone, with a semi-soil structure and poor permeability. It is easy to soften under rainfall or surface water infiltration conditions, forming a weak structural surface. The earliest deformation of the slope occurred on June 14, 2021, and then it continued to slide slowly. The toe of the slope was destroyed first, and the upper part suffered delayed destruction about 5 months later. The sliding surface was finally connected, showing typical traction-type deformation characteristics. It shows that the landslide starts from the lower part of the slope, and the toe support should be given priority in reinforcement and management. The internal causes of landslides are mainly special landforms and complex rock and soil structures, while the external causes include artificial excavation and heavy rainfall. Among them, although the excavation work caused some disturbance, the unreasonable drainage layout and the long construction period led to a large amount of rainwater infiltration, which became the main triggering factor. Therefore, the focus of governance should be on improving the drainage system to reduce the impact of rainfall infiltration. This study reveals the progressive deformation mechanism of the typical traction slope of Tianxi Highway under the combined effects of complex geology and rainfall-excavation, clarifies the characteristics of the sliding surface and the main causes, and has important reference value for similar slope stability analysis and engineering prevention and control.