引红济石引水隧洞围岩力学特性研究

引红(红岩河)济石(石头河)引水隧洞围岩断层带破碎松软,岩石强度低,自稳能力差,易产生大变形。以上不良地质条件使其隧洞施工过程中经常会遇到TBM卡机等一系列特殊问题。针对引红济石引水隧洞施工中存在的软岩隧洞大变形问题,首先开展了X射线衍射、崩解试验,分析了试样的组成成分、黏土矿物含量对崩解性影响;再通过一系列单轴压缩试验、三轴压缩试验和蠕变试验研究了该类岩石不同应力条件下的变形破坏特征及蠕变特性。试验结果表明,该类岩石含有大量的黏土矿物(33.49%),对水比较敏感,遇水膨胀易崩解,导致岩体软化;试样具有较大塑性压缩变形,其应力-应变曲线为应变强化型,且没有明显的峰值。基于试验研究成果和现场监测数据,对该软岩隧洞大变形机制进行了分析,并提出了在围岩与管片之间安装聚氨酯缓冲层的新型支护方案,通过数值计算对支护方案的合理性进行了验证。分析结果表明:聚氨酯缓冲层可以很好地吸收围岩形变压力,避免应力集中带来的管片错台,从而大大减小管片上破坏区的产生。研究成果对该类岩体中隧洞的设计施工以及长期稳定性分析具有重要的参考作用。

Mechanical properties of surrounding rock in diversion tunnel of water diversion project from Hongyan River to Shitou River

The rock is highly fractured with low strength and poor self-stability in the diversion tunnel of water transferring project from Hongyan River to Shitou River. Due to the large deformation of the soft rock tunnel, a series of special problems such as TBM jamming occurs during tunnel construction. This paper is aimed to analyze the effects of sample composition and clay mineral content on the disintegration through X-ray diffraction and the disintegration test. In addition, the deformation and failure characteristics and creep properties of rock mass under different stress conditions are studied through a series of uniaxial compression tests, triaxial compression tests and the triaxial creep tests, respectively. The test results show that the surrounding rock is softened, because the clay minerals (33.49%) like montmorillonite and illite of the rock are sensitive to water. The sample has a large plastic compression deformation, and its stress-strain curve presents a strain-hardening type but no obvious peak intensity. The large deformation mechanism of the soft rock tunnel is analyzed, and a new support technology for installing polyurethane buffer layer between surrounding rock and lining is proposed based on the experimental studies and on-site monitoring data. The rationality of the proposed support technology is also verified through the numerical calculation. The results show that the polyurethane buffer layer can absorb the deformation pressure of the surrounding rock, and avoid the dislocation of segment caused by stress concentration, which can greatly reduce the failure zone of the lining. Research results of this study provide significant references for the tunnel design and construction as well as long-term stability analysis.