考虑质量迁移的全风化花岗岩隧道突水突泥试验

Test of Water and Mud Inrush in Completely Weathered Granite Tunnels Considering Variable Mass Properties

为研究全风化花岗岩隧道突水突泥变质量渗流特征及灾害演化机理,自行设计了一套可考虑质量迁移及三向应力状态的大型室内突水突泥试验系统。该试验系统主要由加载系统、渗流系统、泥水回收系统组成,具备模拟地层三向应力状态的特点,且设计的渗流系统能较好地模拟颗粒迁移特性。利用该装置系统开展不同水压力及围压下的突水突泥演化试验。结果表明:①全风化花岗岩隧道突水突泥灾害演化是渗流-侵蚀强耦合过程,岩体颗粒在水力作用下发生侵蚀流失,致使岩体孔隙、渗透率增长,进而再次加快颗粒迁移,促使涌水量不断增长;同时,随颗粒物不断迁移,水流流态可能由线性流向非线性流发生突变,最终诱发突水突泥灾害。即,颗粒迁移是突水突泥演化的内因,水流流态的转换是灾变的关键;②突水突泥灾变风险随水压力增加而增加,特别是当水压力达到0.6 MPa时,颗粒流失量达到总质量的11%,涌水量更达到395.84 mL·min^(-1),是低压力(0.4 MPa)条件下的4.3倍,且水流流态也由线性流向非线性流转变,表明存在临界水压力促使灾害发生;③突水突泥灾害演化随围压加大而逐步加快,尤其是对灾害演化的初始阶段,表征围压的增长显著加快灾害的初始演化速率并缩减灾害预防时间,因此在高围压环境下须重点监测初期的渗流侵蚀特性。

To study the variable-mass seepage properties and disaster mechanism of water and mud inrush in completely weathered granite tunnels, a testing system that can induce mass transfer and apply triaxial stress was designed. The testing system consisted of a load system, a permeability system, and a collection system of water and mud, which could simulate the three-dimensional stress of the stratum and particle transfer properties. Using this system, the effects of water pressure and confining pressure on water inrush evolution properties were investigated. The test results demonstrate three things. First, the evolution of water and mud inrush from completely weathered granite is a seepage-erosion coupled process. The mass particles transfer under the effect of water pressure, thus increasing the porosity and permeability of the stratum. This, in turn, further increases the water flow and particle transfer. Under the transfer of particles, the flow pattern may change from a Darcy to non-Darcy flow, which finally induces the disaster. The experiment shows that particle transfer is the internal cause of disaster, and the changeability of the flow pattern is the key reason for the disaster. Second, the evolution properties of water and mud inrush increase with increase in water pressure. When water pressure increases to 0.6 MPa, the transfer mass may be up to 11% of the sample mass, and the water inflow increases to 395.84 mL·min～（-1）, more than 4.3 times of that at 0.4 MPa, indicating that the critical value that induces the disaster was obtained. Third, the evolution of water and mud inrush, in general, increases with an increase in the confining pressure, particularly in the initial evolution stage, indicating that an increase in the confining pressure accelerates the initial evolution rate and decreases the prevention time. This suggests that monitoring of initial seepage-erosion properties should be addressed under the high confining pressure state.