极高地应力软岩隧道预应力锚索支护技术研究

Research on Prestressed Cable Support Technology for Soft Rock Tunnel with Extremely High Geostress

依托在建薄层炭质板岩隧道,分析极高地应力作用下支护结构钢架扭曲、结构侵限等大变形问题原因,通过工程类比及施工经验总结,提出预应力长、短锚索组合的柔性支护设计方案。采用数值模拟研究高地应力作用下软弱层状围岩变形,计算结果表明,设置锚索可有效控制围岩变形,剪胀对岩体变形的影响较大,软岩隧道考虑一定的剪胀性是符合工程实际的。当长、短锚索按环向间距1m、纵向间距0.6m交错布置时,施工工序较单一,单次开挖时无须进行锚索成孔设备转换,工效高。

Relying on the thin-layered carbonaceous slate tunnel under construction, this paper analyzes large deformation problems such as steel frame distortion and structural intrusion of the supporting structure under extremely high geostress. Through engineering analogy and construction experience summary, this paper puts forward the flexible support design scheme of prestressed long and short anchor cable combination. The numerical simulation is used to study the deformation of soft layered surrounding rock under the action of high geostress. The calculation results show that the setting of anchor cables can effectively control the deformation of surrounding rock, and the influence of dilatancy on the deformation of rock mass is large. It is in line with the engineering practice to consider certain dilatancy for soft rock tunnel. When the long and short anchor cables are staggered according to the circumferential spacing of 1 m and the longitudinal spacing of 0.6 m, the construction process is simple, and there is no need to convert the anchor cable hole forming equipment in a single excavation, so the work efficiency is high.