破碎炭质板岩隧道掌子面预加固参数优化研究

Optimization Study on Pre-reinforcement Parameters in Tunnel Face with Fractured Carbonaceous Slate

云南滇西地区破碎炭质板岩隧道开挖过程中常发生大变形破坏,如何有效控制变形是研究的热点。依托大临铁路杏子山隧道破碎炭质板岩大变形段的实际情况,在不断增加初期支护强度及措施仍然无法有效控制变形的前提下,提出以玻璃纤维锚杆预加固掌子面为核心的隧道变形控制技术措施,采用数值模拟的研究方法,从掌子面挤出变形及预收敛变形等对掌子面预加固技术参数(锚杆加固长度、锚杆密度)等进行优化分析评判。研究结果表明,掌子面预加固玻璃纤维锚杆间距宜控制在0.6m以内,每环玻璃纤维锚杆的施工长度应大于6m,搭接长度不应小于3m。最后通过现场实测初期支护变形数据表明,纵向长度12m、搭接长度3m、间距0.6m×0.6m梅花形布置的掌子面玻璃纤维锚杆对于掌子面挤出变形控制效果明显,有效地控制了围岩的变形。研究结论可为类似地质条件隧道掌子面预加固参数选取提供参考。

Large deformation and failure often occur during the excavation of fractured carbonaceous slate tunnel in Western Yunnan Province.Effective deformation control measures are the research hotspot and the urgent needs of construction units.Based on the actual situation of large deformation of fractured carbonaceous slate in Xingzi Mountain Tunnel of Dalin Railway, and on the premise of increasing the strength of initial support and unfavorable measures, this paper proposes the technical measures of tunnel deformation control with glass fiber bolt pre-strengthening tunnel face as the core technical measures.The numerical simulation method is used to set glass fiber anchor reinforcement.From the extrusion deformation of the face and the pre-convergence deformation, the technical parameters of the pre-reinforcement of the face are optimized and evaluated.The calculation results show that the spacing of glass fiber bolts should be controlled within 0.6 m, the length of longitudinal reinforcement should be greater than 6 m and the length of overlap should not be less than 3 m.Finally, the field test data show that the control effect of the glass fiber bolt with longitudinal length of 12 m, overlap length of 3 m and spacing of 0.6 m×0.6 m is obvious on extrusion deformation of the tunnel surface, and the deformation of surrounding rock is effectively controlled.The conclusions can provide reference for the selection of pre-reinforcement parameters of tunnel face under similar geological conditions.