Degradation of Typical Reverse Sand-Mudstone Interbedded Bank Slope Based on Multi-Source Field Experiments

Abstract

The bank slopes in the Three Gorges Reservoir area (TGRA) have experienced obvious deterioration under the action of the periodic fluctuations in the reservoir water level. Generally, laboratory tests have been used to reveal the evolution trend of the slope banks. However, this method has a certain degree of cross-scale problem, especially for the mechanical state in a complex environment. Therefore, in this study, we took the Yangjiaping bank slope in the TGRA as an example and proposed a comprehensive on-site detection method to further reveal the rock mass degradation phenomenon of this typical reverse sand-mudstone interbedded bank slope. Specifically, multi-scale laser scanning, cross-hole acoustic wave detection, and inclination measurements were performed to analyze the fractures, quality, and deformation of rocky banks. The results showed that the deterioration of the bank slope manifested as the expansion, deepening, and widening of the cracks, as well as the peeling off and loosening of rocky banks. Large-scale laser scanning revealed that the deterioration zone was deformed along large fracture zones and layers. Unlike limestone slopes, the intact sandstone underground might be degraded by changes in water. There are few inclinometers and no deformation or weak deformation, which requires long-term monitoring. The relevant research methods provide an important reference for determining the instability and failure trend of the reservoir bank slopes.

Hazard Assessment of Debris Flow: A Case Study of the Huiyazi Debris Flow

“…3 ⃝ various resistances can be simulated; 4 ⃝ the results include mud level, flow velocity, and intensity; and 5 ⃝ the results can be post-processed in GIS. The fundamental assumptions of simulating debris flow motion include the following: 1 ⃝ the motion process of the fluid is a shallow water wave motion mode; 2 ⃝ its motion equation satisfies the fixed-length flow equation; 3 ⃝ the distribution of fluid pressure is a hydrostatic pressure distribution; 4 ⃝ the elevation and Manning coefficient within each calculation grid are unique; and 5 ⃝ the flow pattern within the differential time interval is steady flow. The governing equations of the FLO-2D software are the constitutive fluid equations, including continuity equations and motion equations (dynamic wave momentum equations).…”

“…They often result in the destruction of buildings and other structures, posing serious threats to people's lives and property security. Due to their widespread distribution and significant hazards, research on debris flow disasters is of great importance for disaster prevention and mitigation [4][5][6].…”