贯通充填裂隙类岩石渗流特性试验研究

利用3D打印技术制作平行、合并、T型、斜交以及正交裂隙,通过模具浇筑成贯通充填裂隙类岩石试样,应用低渗透岩石惰性气体渗透测试系统测试不同围压加卸载条件下贯通充填裂隙类岩石渗流特性,研究具有不同渗透结构面试样在不同围压作用下气体渗透率的变化规律。通过试验研究发现:充填物相同情况下,开度相同,形式不同的渗透结构面试样渗透率不同,但数量级上不存在差异,以围压加载25 MPa为例,平行裂隙试样渗透率最大,合并裂隙试样渗透率最小;试样渗透率随围压变化曲线在围压加载阶段高于卸载阶段,不同渗透结构面试样渗透率随围压变化波动幅度不同;围压加载阶段贯通充填裂隙类岩石渗透率与围压关系符合多项式函数;不同试样渗透率对应力敏感系数随围压变化曲线在围压加载阶段变化趋势不尽相同,在围压卸载阶段各曲线变化趋于接近,呈"W"型,贯通充填裂隙类岩石渗透率对应力敏感性受渗透结构面影响。

Experimental study on seepage characteristics of rock-like materials with consecutive and filling fractures

3D printing is used to produce different permeability structural surfaces, and rock-like samples are poured by moulds. The tests on permeability of rock-like samples with consecutive and filling fractures are carried out under loading and unloading pressures. The test system of gas permeability measurement for compact rock is applied in measuring the evolution of gas permeability of structural surface with different permeabilities under different confining pressures. The test results show that the permeabilities of samples with different filling fractures are different, but there is no difference in magnitude when the pressure changes. For example, under the confining pressure of 25 MPa, the permeabilities of samples with parallel fractures and combined fractures are the maximum and minimum values respectively. The variation curves of samples between permeability and pressure in loading process are higher than those in unloading process. The evolution of permeability of samples under different pressures is influenced by the geometrical characteristics of permeability structural surface. In the process of loading, the variation curves between stress sensitive coefficient and pressure of different samples change in a different trend. While in the process of unloading, the variation curves are almost the same and present a 'W' form, and the permeability stress sensitivity of rock-like samples with consecutive and filling fractures is influenced by the permeability structural surface.