浅埋软岩段隧道进洞施工变形特征与失稳分析

Deformation characteristic and instability analysis for shallowsoft rock section during tunnel-entering construction

为研究隧道开挖过程中浅埋软岩段塌方变形特征,对隧道地质情况进行有效辨识,结合隧道施工过程围岩监测数据,并依据地质雷达探测结果建立三维数值模型并进行数值分析。研究结果表明:在隧道开挖阶段,拱底与拱顶位置均出现明显塑性区,伴随掌子面逐渐靠近围岩破碎区域,塑性区范围逐渐扩大并向拱顶右上方及围岩内部转移,破碎区域应力水平较低且位移显著增大,围岩完整性大大降低;不良地质构造是隧道发生塌方大变形的主要原因,降雨和地表水的入渗劣化围岩力学性质加速了隧道灾害的发生。对于隧道五级围岩浅埋段施工,应加强监控量测分析并及时做出预警,对关键部位开展超前地质预报工作。研究结果可以指导隧道塌方灾害的防治,对于实现隧道信息化施工具有借鉴意义。

For the collapse accident and stability problem of shallowsoft rock section during tunnel construction,tunnel geological conditions were effectively identified,and a 3D model were set up for analysis based on the result of geological radar and the monitoring data of surrounding rock. The results showed that a significant plastic deformation zone was formed on the arch and vault during the tunnel excavation process. With the tunnel face gradually close to the broken zone of the surrounding rock,the range of plastic zone was gradually enlarged and transferred to the top right of the vault and its surrounding rock. The stress level was relatively low. The vertical displacement of the broken area increased significantly,and the integrity of the surrounding rock was greatly reduced. The main reason for the large deformation of the tunnel was the poor geological structure and the mechanical properties of the surrounding rock due to rainfall and surface water infiltration accelerated the tunnel disaster. For the construction of the tunnel soft rock section in the five class surrounding rock,analysis of the monitoring should be strengthened and early warning should be made in time,the advance geological forecast should be developed in the key parts. The results of the study could give guide to the prevention and control of the landslide of the tunnel disaster,which was of great significance for tunnel informatization construction.