基于非接触测量技术裂隙岩体隧道开挖局部损伤分析

Analysis of Local Damage Induced by Tunnelling in a Fractured Rock Mass Based on Noncontact Measurement Techniques

裂隙岩体损伤区的合理确定对于工程开挖和支护方式的选择至关重要。文章针对这一问题,提出了基于现场岩体结构面的精细测量和表征技术,利用优化后的数值模型定量分析隧道岩体损伤区范围及其力学特性;结合辽宁建兴高速公路某隧道开挖工程实例,采用非接触测量手段采集隧道掌子面的结构面信息,并导入GeoSMA-3D系统,生成接近实际情况的三维空间结构面模型;在此基础上利用颗粒流数值方法 PFC计算确定隧道开挖损伤区范围,并对围岩应力、位移曲线和力链、裂隙分布进行了对比分析。其研究结果表明,力链集中表征围岩开挖扰动程度,裂隙的密度表征围岩开挖损伤程度,而裂隙的贯通则与破坏区对应,从而可以较准确地识别节理岩体隧道工程中岩体损伤区范围及其力学特性;同时利用PFC也较好地模拟了岩石在破坏阶段存在的损伤局部化现象。

The rational determination of an Excavation Damage Zone （EDZ） in fractured rock plays an important role in selecting an excavation method and support pattern. A quantitative analysis was carried out for an EDZ range and its mechanical properties using an optimized numerical model based on the fine measurement and characterization of the structural plane of the rock onsite. Using the excavation of a tunnel on the Jianchang-Xingcheng expressway as an example, information regarding the structural plane at the working face was collected by noncontact measurement, imported into the GeoSMA-3D system, and used to produce a 3D model approximating the actual situation. Based on this, the PFC method was adopted to determine the EDZ range, and comparative analyses of the surrounding rock stress curve, displacement curve, force chain distribution, and fracture distribution were carried out. The results show that the force chain concentration represents the degree of disturbance to the surrounding rock, while the fracture density represents the degree of damage, and the fracture connectivity implies the failure zone, by which the EDZ and the mechanical properties of the fractured rock mass can be accurately identified. The local damage during rock failure can be well simulated by the PFC method.