Research on the Effect of Karst on Foundation Pit Blasting and the Stiffness of Optimal Rock-Breaking Cement Mortar

The existence of karst cavities has an important impact on the safety foundation pit excavation projects. It is engineering guiding value to study influence blasting process pits and how optimize stiffness cement mortar improve effect. Based bench project Shenzhen Dayun Foundation Pit Project, this paper adopts SPH-FEM coupling calculation method cavities, cavity-filling water silt clay rock-blasting blasting. We analyzed development damage rock when cavity grouting filling changes under conditions slightly weathered, moderately weathered strongly limestone. results show that near blasthole direction minimum resistance line, which leads release energy; breaking effect improved filled with medium medium. Under three limestone conditions, after pretreated by grouting, increase in makes area first then decrease implosion, There a critical best micro-, medium- 2.2%, 6.1% 27% blasted mass, respectively, wall stress reach peak value, rock-breaking at time.