Dynamic Response and Failure Process of a Counter-Bedding Rock Slope under Strong Earthquake Conditions

There are massive landslides and potential landslides along the Three Rivers Basin in the Qinghai–Tibet Plateau, which pose a serious threat to the Sichuan–Tibet Railway. A normal shaking table model test was conducted to study the dynamic characteristics and dynamic response of a symmetrical counter-bedding rock slope based on the Zongrong Village landslide. The influences of the dynamic parameters, seismic wave type, and a weak intercalated layer on the slope’s dynamic response were considered. The results showed symmetry between the growth trend of the acceleration amplification factor and other research results. When the input wave amplitude was constant, the acceleration amplification factor increased at first and then decreased as the frequency increased. When the input frequency was near the slope’s natural frequency, the acceleration amplification factor increased at first and then decreased with an increase in the input amplitude and reached the maximum value at 0.3 g. The acceleration amplification factor increased linearly with height in the vertical direction inside the slope but increased slowly at first and then sharply along the slope surface, reaching the maximum value at the slope’s top and exhibiting an obvious “elevation effect”. When sinusoidal waves, Wolong waves, and Maoxian waves with the same amplitude were input, the slope’s amplification effect on the bedrock wave was more obvious. The weak intercalated layer showed the phenomenon of “thin layer amplification” and “thick layer attenuation” in response to the input seismic wave. The slope’s failure process can be roughly divided into three stages: (1) the formation of tensile cracks at the top and shear cracks at the toe; (2) the extension of cracks and the sliding of the slope-surface block; (3) the formation of the main sliding surface.

Comprehensive Method to Test the Stability of High Bedding Rock Slop Subjected to Atomized Rain

In the construction of high dams, many high rock slope failures occur due to flood discharge atomized rain. Based on the steel frame lifting technique and strength reduction materials, a comprehensive method is proposed in this paper to study the stability of high bedding rock slope subjected to atomized rain. The safety factor expression of the comprehensive method and the evaluation method for deformation instability were established according to the similarity theory of geomechanical model, failure criterion, and mutation theory. Strength reduction materials were developed to simulate the strength reduction of structural planes caused by rainfall infiltration. A typical test was carried out on the high bedding rock slope in the Baihetan Hydropower Station. The results showed that the failure modes of the bedding rock slope were of two types: sliding–fracturing and fracturing–sliding. The first slip block at the exposed place of the structural plane was sliding–fracturing. Other succeeding slip blocks were mainly of the fracturing–sliding type due to the blocking effect of the first slip block. The failure sequence of the slip blocks along the structural planes was graded into multiple levels. The slip blocks along the upper structural planes were formed first. Concrete plugs had effective reinforcement to improve the shear resistance of the structural planes and inhibit rock dislocation. Finite element method (FEM) simulation was also performed to simulate the whole process of slope failure. The FEM simulation results agreed well with the test results. This research provides an improved understanding of the physical behavior and the failure modes of high bedding rock slopes subjected to atomized rain.

Numerical Simulation of Dynamic Damage and Stability of a Bedding Rock Slope under Blasting Load

Blasting excavation of a bedding rock slope is a common problem in highway construction in mountainous areas. Accurate simulation of damage area caused by blasting excavation is of great significance for the subsequent maintenance of slopes. Based on a highway construction project in Guangdong province of China, a tensile and compressive damage model was used to simulate the whole process of blasting excavation of a typical bedding rock slope. The analysis results show that damage first appears just around the blasting hole and then develops to the both sides and the bottom of the blasting hole, and finally a large range of damage appears in the lower part of the blasting hole, and the damage depth on the right-side slope is around 2 m, which is in consistent with the scene. Besides, damage also occurs in the middle of the bedding rock mass of the slope. At the same time, the history analysis of vibration velocity also indicates that tensile failure appears on the right-side slope under the blasting hole. Therefore, the stability of the slope can be assessed by analyzing the distribution of damage factors and the vibration velocity characteristics synthetically. In addition, parameter analysis was also carried out to optimize the blasting design by controlling the blasting load so as to obtain the ideal blasting excavation effect and ensure the stability of the slope under blasting load.