软弱断层流变对地下洞室围岩力学效应的粘弹塑性分析

本文就鲁布革水电站地下厂房洞室附近两处断层的流变性态对主厂房洞室围岩稳定力学效应作了粘弹塑性有限元法数值分析。计算中以断层内充填的粘土类矿物质材料的剪切流变属性为研讨的重点,建议了能反映断层厚度影响的新的流变模型及其参数测定方法。 研究表明,在考虑了洞室附近断层的流变性态以后,洞周围岩的受力状况有相当程度的恶化。断层流变对洞室围岩的力学效应主要与其离开洞室的距离D与洞室最小几何尺寸d的比值,即值的大小有关。一般地,当该比值小于1时应予重视,其影响大小还因岩体和断层充填物的物理力学性质的差别以及断层与洞室的相对方位的不同而不同。对于洞周附近局部围岩出观的拉力区段,建议了在设计中采取增设锚杆等辅助的加固措施。

A Viscous Elasto-plastic Analysis on Rheological Effects of Fault Weakness on Underground Openings

This paper presents a viscous elasto-plastic numerical analysis on stability of rock mass surrounding an under-ground opening which is specially cut by two sets of adjacent faults. To simulate the rheological behaviour of the faults, the shear creep characteristics of soft clay fillings inside the fault is analyzed, and, then, an innovative rheological model is proposed to reflect the influence of thickness of the fault. The relevant coefficients involved in the mechanical model can be measured by a special designed apparatus which is discribed in the paper.The results show that by considering the rheological behaviour of faults neighbouring an opening, the loading state of surrounding rock mass is deteriorated considerably. The creep effects of faults on an oponing are dependent mainly on the ratio of fault distance (D) away from the opening and the geometry scales (d) of the opening, i.e. the yalue of D/d. Usually, e. g., when D/d≤1 , the situation has to be considered seriously. Besides, the influence is also related to the physical properties of rock mass as well as the fillings of faults, and the relative position and direction between faults and opening. Local implemental reinforcements by adopting bolts and shotcrete lining support are suggested in region of surrounding rock mass where tensile stresses appeared.