泥化弱胶结软岩地层中矩形巷道的变形破坏过程分析

在西部地区,一定数量的矿区处于泥化弱胶结软岩地层,此类软岩胶结性差、强度低、遇水泥化。矩形是采区巷道的常用型式,但其断面受力不均、稳定性差。在上述软岩地层中的矩形巷道承载力低、变形量大、变形持续时间长,给煤矿的安全生产带来极大困难。以内蒙古新上海一号煤矿皮带顺槽矩形巷道为背景,运用FLAC3D软件中的Cvisc黏弹塑性模型,对矩形巷道的变形破坏进行了数值模拟,并将模拟结果与现场监测结果对比分析。结果表明:巷道开挖支护后,受断面形状影响,矩形巷道四角出现压应力集中和顶板受拉区,巷道顶板下沉量大,底板底臌严重,两帮向巷道挤出;受围岩岩性影响,围岩进入塑性的时间快短、范围大,塑性区超出了支护体的作用范围,造成锚杆(索)的锚固效果难以完全发挥,围岩出现整体滑动的现象;巷道变形呈现出流变变形的特性,变形量随时间持续增加,持续的蠕变变形超出了支护体的可控范围,最终引起巷道的失稳破坏。

Deformation and failure process analysis of rectangular roadway in muddy weakly cemented soft rock strata

In west China, a certain number of mining areas are in the mud weakly cemented soft rock strata; these soft rocks have the properties such as poor cementation, low strength and mudding when encountering water. Rectangle is a common pattern of mining roadway, but the wall rock stress is nonuniform and its stability is poor. In the soft rock strata, the rectangular roadway bearing capacity is low, and deformation is large and will last for a long time; these bring great difficulties for the safety of coal mine production. The belt crossheading rectangular tunnel of the new Shanghai No.1 coal mine in Inner Mongolia is taken for example, the rectangular tunnel deformation and failure are simulated through the Cvisc viscoelastic plastic model of FLAC3D. The simulation results are compared with in-situ monitoring values. The results show that: Influenced by cross-section shape, compressive stress concentrate in the four corners, zone of tensile stress is significant in the roof, roof subsidence is big, the floor heave and sides deformation are serious. Influenced by surrounding rock lithology, surrounding rock mass plastic zone is bigger and it causes support structure is difficult to fully play the effect, and surrounding rock appears the phenomenon of whole sliding. In addition, the deformation of surrounding rock exhibits rheological deformation characteristics, deformation quantity increases with time, continuous creep deformation is beyond the controllable limit of support body, eventually causes the instability and failure of the tunnel.