浅埋软岩隧道大变形特征及控制措施

为了解决浅埋软岩隧道在开挖过程中发生大变形的问题,依托在建隧道工程,分析隧道初支变形及破坏特征,并利用数值模拟软件对大变形原因进行分析,提出合理的变形控制措施。结果表明：洞口浅埋段围岩受到开挖扰动和地下水影响,围岩变形量大,纵向变形分布不规律;开挖初期变形快且变形速率大,最高达到38.4 mm/d;变形持续时间长,变形后期能达到10.2 mm/d;变形主要发生在上、中台阶开挖阶段,约70%;初支应力过大,且塑性区过度发展是隧道发生大变形的主要原因。根据现场监测数据和数值模拟结果提出优化工法、提高支护参数、进行洞内降水和加大预留变形量的综合处治措施。研究结果可为类似软岩隧道的大变形预防与处置提供参考。

Study on Large Deformation Characteristics and Control Measures of Shallow Buried Soft Rock Tunnel

In order to solve the problem of large deformation of shallow soft rock tunnel during excavation, this paper relies on the tunnel project under construction, analyzes the deformation and failure characteristics of the initial support of the tunnel, and uses numerical simulation software to analyze the cause of the large deformation and propose a reasonable deformation control measures. The results show that the surrounding rock at the shallow buried section of the cave entrance is affected by excavation disturbances and groundwater. The surrounding rock has a large amount of deformation and the longitudinal deformation is irregularly distributed; the initial deformation of the excavation is fast and the deformation rate is large, up to 38.4mm/d; the deformation lasts for a long time , The deformation can reach 10.2mm/d in the later stage of deformation; the deformation mainly occurs in the upper and middle step excavation stage, about 70%; the initial support stress is too large, and the excessive development of the plastic zone is the main reason for the large deformation of the tunnel. According to on-site monitoring data and numerical simulation results, comprehensive treatment measures are proposed to optimize construction methods, improve support parameters, carry out precipitation in the cave, and increase the amount of reserved deformation. The research results can provide references for the prevention and treatment of large deformations similar to soft rock tunnels.