板状溶洞充填物软化支护结构稳定性影响分析

Stability Effect Analysis of Filling-material Softening Support Structure of Platelike Caves

文章通过对某高速公路隧道板状岩溶充填物软化进行数值试验,探索了岩溶充填物软化对支护结构稳定性的影响。在无支护条件下,充填物的软化导致其自身位移的显著增加,初期支护对端部充填物位移产生了较好的约束,有效阻挡了软化充填物的下漏。岩溶部位的支护结构出现拉应力,并随着充填物的软化显著增加。岩溶充填物软化前后支护结构出现负弯矩的部位基本相同,最大负弯矩均出现在拱顶岩溶处,充填物的软化大幅增加了此部位出现拉裂破坏的风险;而隧道支护结构出现正弯矩的左部底角以及右部拱肩,可能导致支护结构出现压剪破坏。此外,充填物软化后,顶拱岩溶充填物浅部出现了大范围的压剪破坏区域,若无外部结构支护,将逐步向内垮塌或发生泥化突涌。

Through the numerical test on the filling-matedal softening of plate-like karst in an expressway tunnel ,this article discussed the effect of karst filling-material softening on the stability of supporting structure.Under unsupported conditions, the softening of filling materials caused a significant increase in its displacement,tbe initial support had a better constraint on the displacement of filling materials at end parts, which effectively blocked the stratigraphic leak of softened filling materials.The tensile stress appeared in the supporting structure of karst site and increased significantly with the softening of filling materials.The supporting structure had basically the same part showing the negative moments before and after the softening of karst filling materials, and the maximum negative moments were found in the karst part at the dome, the softening of filling matedals significantly increased the risk of tensile failure at this area; at the left bottom corner and at right shoulder of tunnel support structure showing the positive bending moment, it can lead to compression and shear failure of supporting structure.In addition, after the softening of filling materials, a wide range of compression and shear damage area was shown at the shallow part of top-arch karst filling material,and if no external structural support, it will gradually collapse inward or cause the mud gushing.