Investigation of the acoustic emission characteristics of artificial saw-tooth joints under shearing condition

Shear failure of rockmass along a weak plane occurs frequently in rock slopes and in underground tunnels. To study the shear behaviour and acoustic emission (AE) characteristics of joints under different experimental conditions (asperity height, shear rate, and normal load), irregular artificial saw-tooth joints with different asperity heights were sheared in the laboratory, and the AE signals were detected and analysed. The results demonstrated that the strength of the joints increased with increases in normal load and asperity height, while the strength of the joints first increased and then decreased when the shear rate was elevated. The ideal curve of the cumulative hits could be divided into a quiet period, a slow rise period, and a sharp growth period, which could be used to monitor and predict the potential shear failure of the joints. The higher the asperity was, the higher the peak energy rate and the lower the peak hit rate, and cumulative hits at failure were because of differences in asperity size and number. The peak hit rate and cumulative energy tended to increase gradually with the decrease in shear rate, and the minimum peak hit rate and energy rate at failure were both attained at the maximum shear rate. In addition, curves of the energy rate and hit rate showed large fluctuations at higher shear rates. The peak energy rate and cumulative energy under low normal stress could be greater than the peak energy rate and cumulative energy under high normal stress, and the peak hit rate and cumulative hit number under high normal stress could be larger than that of under low normal stress.     

Energy evolution analysis and failure criteria for rock under different stress paths

Acta Geotechnica - Triaxial loading and unloading tests on marble specimens under different stress paths were conducted to investigate the characteristics of energy evolution in rock deformation...     

深部煤矿地下水温对矿井涌水量预计的影响

随着我国煤矿开采深度增加,地温、含水层水温升高,相应地含水层渗透系数增大,渗透系数的变化会对矿井涌水量产生一定影响。矿井勘探时期对该问题重视不够。以赵楼煤矿为例,考虑地下水温对渗透系数影响,采用解析法预计了矿井正常涌水量,预计结果为398.53m3/h,与不考虑地下水温变化情况相比较,增加59.63m3/h,增加幅度为17.60%,表明地下水温是影响深部煤矿矿井涌水量的重要因素。