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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。
In order to study the evolution law of permeability and porosity of columnar jointed rock mass under multiple confining pressure cycles, three models of cyclic loading and unloading model tests of columnar jointed rock mass were carried out by using tight rock inert gas permeation testing device , The change process of permeability and porosity under the condition of loading and unloading under cyclic confining pressure was measured for similar materials of columnar jointed rock mass. The relationship between permeability, porosity and confining pressure and the sensitivity to stress were studied. The experimental results show that the permeability and porosity of the columnar joint material change greatly during the first confining pressure loading stage, and the initial state can not be restored after the confining pressure unloading. In the subsequent stage of confining pressure circulation loading and unloading, The permeability and porosity of the jointed rock mass are less affected. The loading stage, permeability and porosity are all power function relations with the confining pressure. In the unloading stage, the permeability and confining pressure are power function, and the porosity and confining pressure index The sensitivity of permeability and porosity to confining pressure changes decreases with the increase of confining pressure. After unloading of confining pressure, the sensitivity of permeability and porosity to confining pressure can be restored. In each confining pressure cycle At the loading and unloading stage, the relationship between permeability and confining pressure is bi-modal, and the first peak is always larger than the second peak. The relationship between permeability and permeability during the period of confining pressure loading The relation between porosity and permeability is the exponential function in the unloading stage of confining pressure. The greater the porosity of columnar joint material is, the stronger the sensitivity of permeability to porosity is. The sensitivity of permeability of columnar joint material to the variation of porosity Inclination with the cylinder The relationship curve is bimodal, and the first peak is greater than the second peak.