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利用离散元软件PFC2D对岩溶隧道开挖前后的岩溶空洞进行了数值模拟,接触模型选用平行黏结模型,分析了岩溶空洞分别位于隧道上方、下方、右侧、斜上方45°、斜下方45°工况时由于隧道开挖而引起的地层变形对岩溶空洞稳定性的影响,直观地描述了岩溶空洞失稳破坏现象,分析结果表明:岩溶空洞位于隧道上方和下方时,空洞拱顶首先出现岩土体松动并塌落,拱底岩土体出现松动但在重力和上方塌落土体的作用下未发生移动;位于其他位置时,靠近隧道一侧的空洞围岩变形比远离隧道一侧的空洞围岩变形大;隧道与岩溶空洞间的围岩由于应力集中易产生过大变形和岩土体破坏,对空洞稳定性影响较大。研究岩溶空洞的稳定性及失稳破坏的演变过程,为岩溶隧道的设计和施工提供借鉴与参考。
The discrete element software PFC2D was used to simulate the karst cave before and after karst tunnel excavation. The parallel model was used to select the contact model. The karst voids were respectively located above, below and to the right of the tunnel, with 45 ° obliquely above and 45 ° obliquely below The effect of formation deformation caused by tunnel excavation on the stability of karst cavities is described visually. The instability of karst cavities is described visually. The results show that when the karst voids are above and below the tunnel, The body loose and slump, but the rock and soil in the bottom of the arch are loose but not move under the action of gravity and the collapsed soil above. In other positions, the deformation of the hollow surrounding rock near the tunnel is less than the distance The deformation of surrounding rock is large; the surrounding rock between the tunnel and karst cave is easy to produce excessive deformation and destruction of rock and soil due to stress concentration, which greatly affects the stability of the cavity. Studying the evolution process of the stability of karst voids and the failure of instability, and providing reference and reference for the design and construction of karst tunnel.