隐伏溶洞对隧道围岩稳定性影响规律及处治技术

以鄂西山区隧道工程实例为依托,在溶洞调查与统计分析的基础上,从岩溶的溶洞体积、形态特征、溶腔充填物特征以及涌水通道类型等方面,对鄂西山区岩溶进行分类,得到鄂西山区岩溶发育特征,即溶腔体积不等、形态多样、溶腔充填物种类多、涌水通道复杂。采用数值模拟方法,分析不同位置的隐伏溶洞对隧道围岩的应力场、位移场影响情况,得出随隐伏岩溶位置变化,围岩应力分布有所不同;溶洞位置由隧道顶部向隧道底部变化过程中,隧道顶部围岩最大沉降由大到小依次为拱肩延长线、边墙一侧、拱脚延长线、拱顶上方、底板下方;随着溶洞位置的降低,隧道拱顶围岩水平最大收敛值由大到小依次为拱肩延长线、拱顶上方、边墙一侧、底板下方、拱脚延长线;随着溶洞位置的降低,隧道周边围岩沉降量由大到小均为拱顶、拱腰、拱脚、底板。基于岩溶类型特征、数值模拟围岩应力场、位移变化情况结果,提出岩溶区隧道揭露溶洞处治原则。以花果山隧道为例,开展溶洞处治原则与方法应用,提出针对性的处治方案。

Influence of concealed karst cave on surrounding rock stability and its treatment technology

On the basis of the investigation and statistical analysis of karst caves of tunnel project in E-Xi mountains area, they were classified according to the karst cave volume, shape, cavity filling material and water gushing channel type. The result presented that the karst cavities in the mountains area of E-Xi were of different sizes, various shapes, various cavity filling materials and complicated water gushing channel. The changes of stress field and displacement field of tunnel surrounding rock under the influence of different location of hidden karst cave were studied through numerical simulation analysis, which showed that the high stress area and low stress area of surrounding rock were different with different location of hidden karst cave. With the changes of location of karst cave, the maximum settlement value from large to small were spandrel extension line, sidewall, spandrel extension line, top of arch, bottom of slab. With the descend of the location of the karst cave, the distribution rule of the maximum horizontal convergence from large to small were spandrel extension line, above the arch crown, sidewall, below the bottom plate, spandrel extension line. With the descend of the location of the karst cave, the deformation law of surrounding rock the settlement of tunnel from large to small were vault, haunch, arch foot, base plate. Based on the characteristics of karst type, the results of numerical simulation of stress field and displacement change of surrounding rock, the prevention and control principles of karst cave were sorted out. Huaguoshan tunnel was taken as an example to explain in detail and the treatment scheme was put forward.