Analysis on the main structural factors controlling rockfalls in downtown of Ansai, Shaanxi Province

Abstract

An anticlinal structure with an axis plane along Yanhe river and a strike of about 330° is developed in the bedrock strata within the main urban area of AnSai County. In the bedrock strata, there are generally two groups of tensile joints parallel to the fold axis plane (320°-340°) and vertical (40°-60°), and two groups of conjugate shear joints diagonally intersecting the fold axis. The first group of conjugate shear joint planes struck direction near N-S (0°-10°) and near E-W (80°-90°), while the second group of conjugate shear joint planes strikes direction 100°-120° and 200°-210°. The multiple groups of joints with different strike directions developed in the bedrock have a strong control effect on the development of the collapse structure control plane with the same strike distribution in the study area. In the first group of conjugate shear joints, the near E-W (80°-90°) distributed joint planes control strongly the most developed collapse structure control planes in the study area, and it has the highest correlation with the development of rock collapse in the study area. Secondly, two groups of tensile joint planes control two groups of highly developed rock collapse structural control planes with the same strike, and the second group of conjugate shear joint planes controls two groups of relatively less developed rock collapse structural control planes with the same strike.

Keywords

• geological disaster
• rock collapse
• structural control planes
• bedrock joints
• loess plateau