高地应力软岩隧道的变形规律

The deformation pattern of soft rock tunnels with high ground stress

为研究高地应力软岩隧道变形规律,基于41座隧道68个监测断面的实测数据统计,定量分析高地应力软岩隧道的变形量与岩体抗压强度、围岩完整性、隧道地应力、隧道埋深、侧压力系数、地下水、岩体基本质量指标和支护刚度等因素的关系。研究结果表明:高地应力软岩隧道围岩大变形是围岩地质条件、设计、施工参数及其它多种因素综合作用的结果,其中地应力、围岩特性和支护措施影响最大,案例统计结果可基本揭示我国交通隧道在高地应力软岩大变形控制技术发展水平。高地应力软岩隧道变形具有显著的时空效应,随时间呈现快速增长—持续增长—趋于稳定的变化规律。变形协调系数前期受开挖影响,变化浮动较大,但当仰拱施作后,变形协调系数很快达到稳定,验证和强调了封闭成环对变形控制的关键作用;随着大变形等级的提高,仰拱施工后变形占比减小。

In order to study the deformation law of soft rock tunnels within high geo-stress,the paper quantitatively analyzed the relationships between the deformation value with the compressive strength of rock mass,the integrity of surrounding rock,the geo-stress&depth of tunnel,the coefficient of lateral stress,the ground water,the value of basic quality[BQ]and the stiffness of support of soft rock tunnel within high geo-stress based on the statistics of monitoring dada from 68 monitoring sections in 41 tunnels.The results indicated that the large deformation of surrounding rock in soft rock tunnel within high geo-stress was the outcome of the comprehensive action of geological conditions of surrounding rock,the design and construction parameters and other factors.Among them,the in-situ geo-stress,surround-ing rock characteristics and supporting countermeasures had the significant influence.The results from the case statistics could preliminarily reveal the development level of the control technology of large deformation of soft rock traffic tunnel within high geo-stress in China.The deformation of soft rock tunnel within high geo-stress had noticeable time-space effect with the variation patterns from the rapid growth stage to the continuing growth stage and then the stabilizing stage at last with time.The deformation coordination coefficient was mostly affected by the excavation with large fluctuations in the early stage,but tended to be stable very soon after the inverted arch was constructed which also verified and emphasized the key role of the ring closure to the deformation control from another perspective.With the increase of large deformation grade,the proportion of the deformation after construction of inverted arch decreased.