含水层砂岩应力应变全程非线性渗流的试验研究

Experimental Investigation of Non-linear Seepage of Aquifer Sandstone under Complete Stress-Strain Process

砂岩是煤系地层中主要的含水层之一,砂岩的非Darcy流渗透特性参量的变化规律是揭示煤矿突水机理的基础.本文通过归纳分析了非Darcy流渗透特性参数的由来和具体的物理意义,利用自主研发的圆柱形标准岩样渗透性测试系统配合使用MTS816.02电液伺服岩石力学实验系统对含水层砂岩试样进行了非Darcy流渗透性测试.得到了砂岩试样的渗透率、非Darcy流β因子和加速度系数.研究结果表明:在弹性阶段,渗透率减小,加速度系数增大,在轴向应变为1.0%附近,渗透率最小,加速度系数最大.在峰值应力状态下,非Darcy因子β最小.渗透率与加速度系数之间的关系可以用幂乘函数描述;渗透率与非Darcy流β因子之间的关系可以用ExpDec模型描述;非Darcy流β因子和加速度系数之间的关系可以用BoxLucas模型描述.

Sandstone is one of the main aquifer in coal measures strata. Its variation law of non-Darcy permeability parameters is the key to explore mechanism of water inrush in coal mine. The origin and specific physical significance of non-Darcy flow permeability parameters are analyzed. A fluid flow test is conducted to investigate the permeability parameters using MTSS16.02 and a designed seepage experimental system. The permeability, non-Darcy flow β factors and acceleration coefficient are obtained. The experimental results show that permeability value decreases to minimum, while acceleration coefficient increases to maximum when axial strain is 1.0%, in elastic stage. The value of non-Darcy flow β factors reaches minimum with highest stress. The relationship between permeability and acceleration coefficient can be described by power multiplication function. The relationship between permeability and non-Darcy flow β factors can be described by ExpDec model. The relationship between non-Darcy flow β factors and acceleration coefficient can be described by BoxLucas model.