隧道围岩压力和锚杆轴力的特性分析

Characteristic Analysis of Rock Pressures and Rock Bolt Forces Based on Monitoring

结合江西武吉高速公路隧道15个典型断面的监测信息,分析围岩压力和锚杆轴力的稳定值和稳定时间变化规律。结果表明,锚杆未能充分发挥支护作用,应加强锚杆锚固力;隧道位置、施工方法及围岩级别对围岩压力和锚杆轴力的稳定时间有影响。利用围岩压力经验公式计算值与实际监测值进行比较,分析了经验公式对实际隧道工程的适用性。结果表明,深浅埋法计算值比实测值大;系数法和普氏法计算值与实测值相近,但计算结果有赖于参数的选取;泰沙基法计算深埋隧道的围岩压力误差较大。考虑隧道埋深和围岩级别的影响,获得围岩压力与隧道埋深的乘幂关系,以及围岩压力与围岩级别的指数拟合公式。通过监测数据获得的一些规律性结论,可为隧道结构设计和结构计算提供参考。

Variation of stable values and stable time of rock pressures and rock bolt forces was analyzed based on monitored data of 15 typical sections in Jiangxi Wuji highway tunnel. It was found that rock bolts were understressed and stable time of rock pressures and rock bolt forees were affected by tunnel overburdens, construction method and rock grades. The applicability of empirical formula to practical engineering was analyzed after comparing calculated values of rock pressures with measured ones. Results obtained by deep and shallow tunnel method were larger than measured ones; calculated values by coefficient method and M. M. Protojiyakonov theory were closed to measured values, but the results depended on selected parameters; big error resulted when Terzaghi＇s method was applied to deep tunnels. Considering the effect of tunnel overburdens and rock grades, a power function and exponentially fitted formula of rock pressure was deducted. Regular conclusions gotten from monitoring would provide information for tunnel structure design and calculation.