Effect of Near-Wave Field Mining Tremors on the Rock Bolt Support Behaviour within Stress Domain

One of the most serious hazard in the underground copper mining in Poland is the roof fall hazard. The scale and intensity of this type of events depends on several factors. Due to seismic activity, weaker roof strata can loosen and deform, generating additional load on the rock bolt support. The type of load depends strictly on the course of stratum deformation as well as on the intensity of the dynamic effect in the form of a seismic wave. Continuous monitoring is then necessary to determine the risk level of stability loss within existing excavations in order to minimize the probability of serious accidents. The following study analyses the impact of tremors recorded within the near-wave field upon the stress change in the instrumented rock bolts.

The Research Reviewed of Subway Construction Impact on Stratum Deformation Law

The research achievement of strata movement law caused by subway construction and control standards was summarized and analyzed, and point out that this research on the laws of strata movement (or deformation) caused by subway construction mainly focused on three aspects. The first was research on the ground vertical settlement laws perpendicular to the tunnel excavation direction. The second was research on the ground vertical settlement laws parallel to the tunnel excavation direction. The third was research on the ground horizontal movement regularity perpendicular to the tunnel excavation direction. Through the analysis of the current research results, it is points out the shortages existing in the research, and deeply research in the future. It may provide the theoretical basis, also for practical engineering application provides a certain technical support.

Influence of Cavity above Tunnel on Stratum Deformation and Failure in Urban Tunnelling

In order to study the influence of cavity above the tunnel on stratum deformation and failure in urban tunnelling, the model test method was adopted based on the parameters of the stratum and tunnel section size in Beijing subway. The stratum responses were obtained under the conditions without ground cavity and with ground cavity above the tunnel. The responses include the stratum stress distribution, stratum settlement law and stratum failure process. It was concluded that the existence of ground cavity above the tunnel worsened the stratum condition and accelerated the progress of stratum deformation and failure. Furthermore, the failure began from the cavity and the damage scope was bigger than that under the condition without cavity according to the test results. The research results can be referenced for the similar tunnel engineering.