爆炸荷载作用下坑道喷锚支护的破坏形态

The Failure Modes of Shotcrete Lining of Tunnel Under Blast Loading

本文在较广泛的爆炸试验基础上,分析了坑道喷锚支护的破坏形态,并根据破坏的受力特点,将其区分为五种类型,即:“结构力学型”破坏、受压破坏、剪切破坏、拉伸剝离破坏和横向断裂.文中还指出,爆炸动载有其动态效应和准靜态效应.准靜态效应下,坑道支护的破坏形态与靜载下的破坏形态相仿,拉伸剝离破坏和横向断裂则是动态效应特有的破坏型式.

According to fairly extensive field explosion tests, the failure modes of shotcrete lining of tunnel (with or without rockbolts)are presented in this paper. Five types of failure mode are distinguished in terms of diferent mechanical responses under blast loadings, i. e, 'structural mechanics' compression, shear, tension slabbing, and transverse cracking. For the structural mechanics mode, lining of tunnel is considered to be isolated from surrounding rock and sustains dynamic loading independently. For the compression mode, local surface layer of shotcrete lining bulges and breaks off because of buckling of steel bars. In the shear mode failures are principally induced by the relative motion of discontinuities in surrounding rock. The tension slabbing is caused by the reflection of blast stress wave on tunnel surface. For transverse cracking mode under blast wave failures are mainly due to lining constrution joints, abrupt changes of tunnel crass-section and portals etc. It is also pointed out that blast loading has quasistatic effect as well as dynamic effect Under. quasi static condition, failure mode of dynamic loading are similar to that under static loading