复杂地层超大断面隧道施工围岩力学特征模型试验

以京沪高速济南连接线港沟隧道穿越断裂破碎带区域为依托工程，研究了复杂地层超大断面隧道施工情况下围岩力学响应特征。研发了大型可拼装式地质力学模型试验系统，搭建了以静态数据采集为基础的应力–应变场监测系统和以光栅测距为基础的位移场监测系统，开展了复杂地层超大断面隧道施工过程力学模型试验研究。通过对试验开挖过程中位移变形和围岩应力变化的实时监测，揭示了超大断面隧道穿越断裂破碎带施工过程的力学演化规律。监测数据表明：位移变形大致可分为“缓慢增加-急剧增大-稳定状态”3个过程，水平收敛位移要早于拱顶沉降进入急剧增大阶段；应力变化也可分为“应力积聚－应力释放－稳定状态”3个阶段。形成的试验方法技术以及结论对类似工程研究具有重要的指导和借鉴意义。

Model test on mechanical characteristics of surrounding rock during construction process of super-large section tunnel in complex strata

Based on Ganggou tunnel of Jing-hu high-speed connection line road which crossed large fault zones, mechanical characteristics of surrounding rock were studied during the construction process of super-large section tunnels under complex strata. For this purpose, a large-scale three-dimensional assembled geomechanical model test system was designed and developed. The system included stress and strain field monitoring systems based on static data acquisition and a displacement field monitoring system based on raster ranging in order to monitor the mechanical response of surrounding rocks during tunnel excavating. Model tests on mechanics in construction process of super-large section tunnel under complex strata were conducted, and the data of displacement and stress were real-time monitored during testing through the pre-buried monitoring instruments at specific positions in the models. The results indicate that the displacement deformation of both horizontal and subsidence can be divided into three phases: slowly increasing phase, sharply increasing phase and steady state phase. The sharply increasing of horizontal displacement starts earlier than subsidence. Meanwhile, the three phases of stress accumulation, releasing and steady state of stress are also revealed. The research methods and results will guide similar engineering practices.