Study On Damage Range Of Surrounding Rock In Underground Caverns

With the development of the Chinese infrastructure, underground cavern is widely usedin the underground project. And blasting is adopted frequently during the course ofconstruction. During the process of rock excavation by blasting, as a result of the action ofdetonation stress wave, remaining rock mass has inevitably been disturbed by blasting. Aftersurrounding rock mass of the cavern under blasting excavation disturbance, the micro cracksemerge induced by the disturbance in surrounding rock mass, formed the excavation damagezone distributed along the boundary of cavern, which may produce potential dangers to thepreserved rock and the constructions built on it. So the control of the blast-induced damagezone and the zone’s factors is a key problem in the rock blast research field.Based on the reading of a large number of domestic and foreign literature, this thesis firstsummarizes systematically the research status of damage rock, detailedly analyzes andevaluates rock blasting theory model and formation mechanism of the blast-induced damagezone.Then it introduces the basic theory and constitutive model of numerical simulation withFLAC3D.It simulates some blasting tests of the whole section in Huangdao’s undergroundproject and determines the damage zone.Finally it changes respectively the explosive dosageof pre splitting holes、buffer holes、main explosive holes and the level of surrounding rockmass rock, which can be helpful to research the blast-induced damage zone’s factors byobserving the model’s plastic zone.The key point of the research in the thesis is shown below:(1) The damage zone of Huangdao’s underground project compares with it detected bythe sound hole’s method, which is to instruct the relationship of levels of surrounding rockand the damage zone.(2) When there are only pre splitting holes in the model, calculating the damage zone oflevels of surrounding rock can help to make some conclusions about the line density of presplitting holes、levels of rock and the damage zone. Then it can fitting a function formula toexpress the relationships.(3) On the basis of the model that has only pre splitting holes, adding buffer holes andmain explosive holes has intensified effects on damage range of surrounding rock.