Influence of Slope Gradient on Distribution Rule of Geostress Field in River Valleys

Abstract

During the construction of hydropower station, the change of slope gradient in river valleys often takes place. In order to study influence of slope gradient change on distribution rule of geostress field, the three dimensional unloading models under different slope gradients were established by finite difference software (FLAC3D). After numerical simulation, the results were as follows: (1) The phenomenon of stress concentration at the bottom of river valleys was obvious, which appeared the typical stress fold. Both the depth of stress concentration zone and the principal stress values significantly increased with the increment of slope gradient. (2) Maximum principal stress values increased less in shallow part of upper bank slope (low stress zone) but increased more in the nearby slope foot with the increment of slope gradient, causing great difference in geostress field of bank slope. (3) There was some difference in released energy of bank slope due to slope gradient change in river valleys. In order to distinguish the difference, stress relief zone was further divided into stress stably released zone and stress instability released zone. Finally, take Ada dam area of the western route project of South-to-North Water Transfer as an example, the results by numerical simulation were reliable through comparing the distribution rule of geostress field for the dam, which could provide important reference for stability of the design and construction of steep and narrow river valleys.

Numerical Analysis and Deformation Mechanism Study on an Excavated High‐Steep Slope of a Hydropower Station

“…During the mechanical parameters inversion, the cohesion of relaxed rock mass with large deformation was reduced by 20%-50% of non-unloaded rock mass, while the friction coefficient was reduced by 50%-60% of non-unloaded rock mass. In the model, the deformation modulus, friction coefficient, and cohesion of the rock masses of grades IV 2 , IV 1 , and III 2 for P 10 t21 and P t21 were mainly inverted. e mechanical parameters of the slope rock mass obtained by inversion are presented in Table 1.…”

“…In recent years, an increasing number of scholars have adopted the numerical simulation methods to analyze slope stability, while the typical numerical simulation method has been the FLAC3D strength reduction method, which was based on finite difference [9][10][11].…”

Geomorphic natural hazard on loess terrain: expansion on the gully sidewall

“…In addition, the matric suction decreased or even disappeared with an increase in water content during rainfall infiltration, resulting in a decrease in soil shear strength, eventually leading to the occurrence of gravity erosion (Lomtadze et al 1977;Tu et al 2009). An increase in the initial slope gradient results in the concentration of shear stress at the sidewall toe and tension stress at the gully shoulder (Pei et al 2013), leading to an increase in the absolute values of shearing forces, followed by slope failure. This indicates that mass failure led to a remarkable change in slope gradient during sidewall expansion.…”