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利用一种岩石裂隙水沙渗透试验系统开展了水沙在平面平行裂隙中流动的滞后性的试验研究,分析了渗流速度-压力梯度闭环曲线的特征,解释了滞后现象的原因.试验结果表明:当渗流速度由零增大到1.77 mm/s再减小到零时,渗流速度-压力梯度曲线自行封闭,形成滞环;由于裂隙开度、粗糙度、沙粒径和沙浓度的不同,滞回曲线呈现凸镜形、月牙形、“8”字形、勺形和裂缝形等多种形状;水沙混合液与岩石裂隙面的接触角变化引起回程中渗透速度沿裂隙宽度方向分布变化,这是岩石裂隙中水沙渗透存在滞后现象的主要原因;沙粒在岩石裂隙面的沉积、水沙在岩石裂隙中运动形态的转变、水沙混合液的粘塑性是岩石裂隙中水沙渗透存在滞后现象的重要原因.
A rock fissure water and sand infiltration test system was used to study the lag of flow and sediment flow in a plane parallel fracture.The characteristics of the closed-loop curve of seepage velocity and pressure gradient were analyzed and the reason of the hysteresis was explained.The experimental results show that: When the seepage velocity increases from zero to 1.77 mm / s and then decreases to zero, the seepage velocity-pressure gradient curves close by itself to form a hysteresis loop. Due to the difference in opening, roughness, sand diameter and sand concentration, the hysteresis The curve shows convex mirror shape, crescent shape, “8 ” shape, spoon shape and crack shape and other shapes; the change of contact angle of water and sediment mixed rock and rock fracture surface causes the distribution of penetration velocity along the crack width direction in the back, This is the main reason for the lagging phenomenon of water and sediment infiltration in rock fissures. The sediment of sand grains in rock fissure surface and the movement form of water and sediment in rock fissures, the viscoplasticity of water and sediment mixture is the existence of water and sediment infiltration in rock fissures Hysteresis of the important reasons.