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

Area of Science:

• Geotechnical Engineering
• Environmental Geology
• Rock Mechanics

Background:

• Reservoir bank slopes, particularly in the Three Gorges Reservoir Area (TGRA), exhibit significant deterioration due to periodic water level fluctuations.
• Traditional laboratory testing methods face cross-scale challenges in assessing the mechanical state of slopes in complex environments.

Purpose of the Study:

• To propose and validate a comprehensive on-site detection method for analyzing rock mass degradation in reservoir bank slopes.
• To investigate the specific degradation phenomena of a typical reverse sand-mudstone interbedded bank slope at Yangjiaping in the TGRA.

Main Methods:

• Employed multi-scale laser scanning to identify and map surface features and deterioration zones.
• Utilized cross-hole acoustic wave detection to assess the internal quality and integrity of the rock mass.
• Conducted inclination measurements to monitor the deformation and stability of the bank slope.

Main Results:

• Observed slope deterioration characterized by crack expansion, deepening, widening, and rock loosening and peeling.
• Laser scanning indicated deformation along major fracture zones and geological layers.
• Sandstone degradation due to water changes was noted, differing from limestone slope behavior; minimal deformation detected, necessitating long-term monitoring.

Conclusions:

• The proposed comprehensive on-site detection method effectively reveals rock mass degradation phenomena in reservoir bank slopes.
• The findings provide crucial insights into the instability and failure trends of TGRA bank slopes, particularly sandstone-mudstone interbedded types.
• Long-term monitoring is recommended due to limited observed deformation, highlighting the dynamic nature of slope stability.