Abstract:

Rockburst is a phenomenon of geological hazard due to excavation in brittle rockmass of high insitu stress, which endangers the engineers and construction equipment. At present, the criterion of rockbusrt can be used to study the possibility of rockbusrt from the macroview, but the knowledge of the mechanism of the delay characteristics of rockburst is insufficient. In the paper, the delay characteristics of rockburst is studied on the basis of the stress release rate (SRR) of the rock mass by means of numerical simulation. The elastic strain energy distribution, the plastic strain energy distribution and the plastic field shape and range under different SRR are analyzed. Conclusions drawn are as follows: With the increase of core modulus reduction value, the SRR shows increase trend in the form of exponent. In the process of excavation, the rockmass deform elastically under the low SRR value. When the SRR value reaches certain degree, the portion of rockmass will be plastic field and behind the plastic region there will arise an elastic strain energy centralized phenomenon. Under different SRR values, the field turns from the shear field to the tensionshear field and the rockburst rank changes under different stress release rates. The investigation can provide an effective way for the study of the delay feature of rock burst.

Key words: rock mass stress release rate, rockburst, delay, elastic modulus reduction