高地应力双隧道施工围岩应力变化规律数值模拟研究

以云县至凤庆高速公路隧道开挖工程为研究对象，采用数值分析和相似模拟相结合的手段，对其处于不同埋深岩层围岩变化规律展开研究。为保证隧道开挖施工安全，分别对隧道拱顶围岩压力、拱腰围岩压力以及上方围岩压力进行监测。基于监测数据分析围岩应力变化规律，明确了隧道开挖对其拱顶上部岩层影响程度和拱腰不同位置岩层应力在应力释放阶段所表现形式。研究表明，拱腰围岩竖向应力在左右隧道开挖整个施工阶段，应力变化曲线主要可分为3种类型，逐渐增大最终趋于稳定型、先增加后快速下降再缓慢增加型和先增加后快速下降至0型；根据拱顶及拱顶上方岩层竖向应力曲线，可将隧道拱顶上方岩层分为3种状态，拱顶上方0~50 m应力释放“高影响区”，拱顶上方50~150 m岩层属于应力释放“次影响区”，拱顶上方150 m以上岩层属于应力释放“缓影响区”。

Numerical simulation on stress variation law of surrounding rock in highground stress double tunnel construction

Taking the tunneling project of Yunxian to Fengqing expressway as the research object，numerical analysis and similar simulation are used to study the change law of surrounding rock strata at different buried depths.In order to ensure the safety of tunnel excavation，the surrounding rock pressure of the vault，the surrounding rock pressure of the waist and the surrounding rock pressure above the tunnel are monitored respectively. Based on the monitoring data，the variation law of surrounding rock stress was analyzed，and the influence degree of tunnel excavation on the upper rock stratum of the arch crown and the manifestation of rock stress at different positions of the arch waist in the stress release stage are defined.
The results showed that the vertical stress of surrounding rock of arch waist can be divided into three types during the whole construction stage of tunnel excavation:gradually increasing and finally becoming stable;first increasing and then rapidly decreasing and then slowly increasing;and first increasing and then rapidly decreasing to 0.According to the vertical stress curve of the vault and the rock stratum above the vault:0~50 m above the vault "high impact zone" for stress release，50~150 m above the vault "secondary impact zone" for stress release，and 150 m above the vault "slow impact zone" for stress release.