循环加卸载下柱状节理材料渗透率和孔隙度演化规律研究

 为了研究柱状节理岩体在多次围压循环加卸载下渗透率与孔隙度的演化规律，利用致密岩石惰性气体渗透测试装置，对柱状节理岩体相似材料进行3次围压循环加卸载模型试验，测量柱状节理岩体相似材料在3次围压循环加卸载下渗透率与孔隙度的变化过程，研究渗透率、孔隙度与围压之间的变化关系以及对应力的敏感性。试验结果表明：在第一次围压加载阶段，柱状节理材料渗透率和孔隙度变化较大，且围压卸载后不能恢复初始状态，在此后的围压循环加卸载阶段，围压变化对柱状节理岩体渗透率和孔隙度的影响较小；加载阶段，渗透率和孔隙度与围压均成幂函数关系；卸载阶段，渗透率与围压成幂函数关系，孔隙度与围压成指数函数关系；随围压增大，渗透率和孔隙度对围压变化的敏感性均减少，围压卸载后，渗透率和孔隙度对围压变化的敏感性可以恢复；在每个围压循环加卸载阶段，渗透率对围压变化的敏感性与柱体倾角的关系曲线均呈双峰形，且第一个峰值总是大于第二个峰值；围压加载阶段孔隙度与渗透率成幂函数关系，围压卸载阶段孔隙度与渗透率成指数函数关系；柱状节理材料的孔隙度越大，渗透率对孔隙度变化的敏感性越强；柱状节理材料渗透率对孔隙度变化的敏感性与柱体倾角的关系曲线呈双峰形，且第一个峰值大于第二个峰值。

Permeability and porosity of columnar jointed rock under cyclic loading and unloading

The variations of the permeability and porosity of columnar jointed artificial rock under cyclic loading and unloading of the confining pressure were measured by using the inert gas permeability test device. In the first stage of confining pressure loading，the confining pressure has a great effect on the permeability and porosity，and the changes of the permeability and porosity are irreversible. In the subsequent stages of cyclic loading and unloading，the change of the confining pressure has a less effect on the permeability and porosity. The relationships between the permeability or porosity of columnar jointed artificial material and the confining pressure were fitted with the power functions during the confining pressure-loading stage. In the unloading stage of confining pressure，the relationship of the permeability and confining pressure can described as a power function，and the one of the porosity and confining pressure can described as an exponential function. The sensitivities of the permeability and porosity to confining pressure decreases with the confining pressure increasing，while the sensitivities of the permeability and porosity to confining pressure can be restored fully after confining pressure unloading. In the each stage of confining pressure loading and unloading，the relationship curves between the sensitivity of permeability to the change of confining pressure and column inclination exhibit a double peak pattern. The value of first peak is greater than the second one. The relationship between the porosity and permeability shows a power function in the loading stage of confining pressure，and a power-exponent function in the confining pressure unloading stage. The sensitivity of the permeability to the change of porosity increases with the porosity increasing. The relationship curves between the sensitivity of the permeability to the change of porosity and column angle exhibit a double peak pattern，and the first peak value is greater than the second one.