中等砂化白云岩小断面隧洞控制爆破技术: 以滇中引水工程玉溪段隧洞为例.

Dolomite sanding is a special karst geological phenomenon in the dolomite distribution area. The medium sanded dolomite rock mass is in a massive and broken structure, so it's very difficult to control blasting and over excavation. In order to reduce the construction risk and the over excavation and consumption, relying on the front section of Chenaju Tunnel of Central Yunnan Water Diversion Project, a study on the optimization of controlled blasting parameters for small section tunnel of medium sanded dolomite was carried out. The LS-DYNA software was used to establish the blasting model of peripheral holes in sanded dolomite, and the effects of different smooth blasting parameters on crack propagation were studied. The reasonable range of smooth blasting design parameters suitable for medium sanded dolomite was proposed. The results show that when the peripheral hole spacing is 30 ~ 70 cm, the radial uncoupling coefficient is less than 2. 6, the minimum resistance line distance is 30 ~ 60 cm, and the peripheral hole density coefficient is 0. 6 ~ 1. 3, the blasting effect is quite well. On this basis, the corresponding controlled blasting technology is summarized, and the construction effect is in good agreement with the numerical simulation results. [ABSTRACT FROM AUTHOR]