No abstract

With the increase of mining depth, rock mechanics conditions become complicates. So the surface subsidence law caused by deep mining is different from the shallow. Based on the finite difference method and rock mechanics theory, the surface subsidence law cased by deep caving mining was studied, the strata movement rule and characteristics of stress distribution of different excavation stage was analyzed systematically. The results of the study can provide certain reference significance for the deep mining to confirm the displacement angle and range of surface subsidence.

During the past decades, the microseismic technique has changed from a simple researching means for rock failure study to a practical method for daily safety monitoring at high geo-hazard tendency mines. This paper introduces the microseismic monitoring system built at a metal mine aiming at the prediction of the geological hazard. The arrangement of microseismic monitoring sensors should take consideration not only of the current mining situation, but also by the aid of experts experiences. By a successful case of prediction for hard brittle failure, the Shizhuyuan microseismic monitoring system was proven to be valid and necessary in the prediction of geological hazard.

In this paper, a series of true triaxial tests indoor with acoustic emission mornitoring were conducted and the characteristics of acoustic emission rate and energy releasing rate in the section adjacent to failure were gained. According to the different characteristics of acoustic emission rate, we divided the events rate into three types which were main shock, foreshock-main shock and cluster shocks. And then, a prediction method for hard rock was put forward according to different events rate types based on the trends of AE signals in the section adjacent to failure for hard rock.

In long term practice of rock engineering, the strength and failure rules based on classical elasticity and plasticity theory is always dominated in judging the safety and stability of practical engineering. However, stress-strain relationship is only a certain state of rock mass in loading process, and it is hard to give an accurate evaluation for the engineers especially due to the diversity and divergence of mechanical parameters. For actual loading process of rock mass is always companied with energy dissipation and releasing, in this paper, we put emphasis on the ratio of dissipated energy to overall absorbed energy in the cyclic loading process. From this point of view, three important sections are gained as follows: a) condensing section: the ratio is higher due to the closing effect of original cracks; b): elastic section: the value of ratio sharply goes down and is nearly a constant in the elastic section; c) approaching to failure section: this is a section closely to the failure because the newly cracks occurs ceaselessly and the ratio value becomes higher.