Tianhong Yang

Stratified rock mass is a common rock mass structure and distributed widely on the earth’s crust. High-density distribution of stratified structural planes in the stratified rock mass has a great influence on the mechanics properties of the rock mass, such as anisotropy of stress and seepage. Therefore, anisotropy is the inherent characteristic that must be considered in the stratified rock mass as well as the stratified rock slope stability. According to the anisotropic characteristics of stratified rock mass, an anisotropic seepage-stress coupled model for the mechanical behavior of stratified rock slope is proposed based on the anisotropy elasticity theory. The model is validated by simulating seepage and stress fields of an idealized slope using the finite element method. The deformation and stress-dependent permeability of the slope are predicted and compared well with the previous study, thus confirming its capability in characterizing the response of rock slope that is dominantly affected by rock anisotropy. Finally, the model is used to simulate the anisotropic properties of a stratified rock slope of Fushun west open-pit mine, China. The simulation is in good agreement with the actual measurement, which means the proposed model is capable of simulating anisotropic properties of the stratified rock slope.

Slope stability analysis is the most important problem in slope engineering design and construction. Open‐pit slope often spans several strata, many of which are relatively weak. There may be faults and weak layers across the whole rock. It is very necessary to study the instability mechanism and stability analysis of multistratigraphic slopes with faults and weak layers. In this paper, taking a complex three‐dimensional slope with fault and weak layer as the research object, the evolution laws of the stress field and damage zone of the slope are analyzed by using the finite element strength reduction method. The results show that the fault and weak layer have different degrees of effect on the slope stability. The fault causes stress concentration and damage to nearby rock mass, and the weak layer causes stress concentration on the slope above it and forms a dangerous slip zone. Then the effect of the fault and weak layer on slope stability is discussed. Because the effect of horizontal structural plane on slope stability is greater than that of the vertical structural plane, the effect of weak layer on slope stability is greater than that of the fault in the slope. The research results can provide a theoretical guidance for the study of slope stability in practical engineering.

Uniaxial compression experiments and acoustic emission (AE) tests were conducted on weakly consolidated sandstone samples with bedding angle of 0°, 45°, and 90° collected from Xiaojihan coal mine in Shaanxi Province, China; the acoustic emission (AE) characteristics of bedding sandstone were investigated, including the influencing mechanism of bedding angle on characteristics, spatial distribution, and b value changes of AE activity. According to the research, AE ringing counting rate and energy rate are the highest and energy release is intense during the loading process when the bedding angle is 0°, and these values decrease and the energy release is gentle with rising of the angle. Based on spatial distribution, the number of AE events was the largest and cluster phenomenon occurs between the bedding plane when the bedding inclination was 0°, which decreased and sprouted along the plane of bedding plane at 45° and which was smaller and evenly distributed in the space at 90°. With the increase of bedding angle, the proportion of large‐scale microcracks decreases and the variation range of microcracks narrows down. Therefore, under the same uniaxial compression conditions, the b value increases by the increase of bedding angle. The research results offer reliable reference to carry out monitoring work on acoustic emission and microseism of mine with layer rock (rock mass).

Comprehensive tests were conducted on a longwall face in China to study mining-induced strata movement and fractures. The first and periodic weightings of the main roof were both captured by microseismic (MS) monitoring and support resistance recording and were 64 and 20 m, respectively. Based on the fracture detection through hydrological observations in a borehole, the roof is clearly divided into three zones: water-conductive zone, horizontal fracture, and continuous zone. Following the field investigation, an innovative finite-difference method (FDM) and distinct-element method (DEM) coupled numerical simulation method was proposed, which features simulating the progressive failure of the rock mass from intact to blocky. The numerical study shows that the proposed coupled method can give reasonable explanations for all in situ tests and handle the progressive caving of the rock layers, as well as the accompanying MS activities and response of the hydraulic supports. The proposed coupled method has advantages over a continuum or discrete method in coal mining simulation. Compared with a continuum method, the coupled method can simulate the deformation and collapse of the overburden strata, whereas the continuum method is only applicable before the first weighting of the rock layer, after which it gives wrong results. In contrast, compared with a discrete method where the blocks are factitiously set before and their sizes are mandatory, the coupled method allows the blocks to form automatically based on the failure state of the rock mass.

Serious geological disasters and environmental damage have been caused by the high-intensity mining in Western China. The mining rate of the working f