具有不同转折角度的复杂单裂隙水头损失试验研究
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摘要
裂隙是岩溶含水系统的重要组成部分,裂隙水流运动对岩溶含水系统水流运动起到重要的控制作用。利用自行设计研制的具有不同转折角度、不同裂隙开度的复杂单裂隙物理模型,通过室内物理试验得到有、无裂隙条件下,水头差变化曲线,并基于能量方程推导得出水流流经裂隙时产生的总水头损失计算式,计算得到不同裂隙开度(1～2.6 mm)、不同流速(0～40 cm/s)条件下,裂隙总水头损失对不同转折角度(0°～165°)的变化曲线,利用修正立方定律和达西-魏斯巴赫公式计算裂隙平行部分的沿程水头损失,总水头损失与之相减得到转折角处的局部水头损失。结果表明:随裂隙开度增大,流速增大,裂隙总水头损失、转折处局部水头损失均呈增大趋势,且流速越大,趋势越明显;对水头损失与平均流速之间的关系曲线进行拟合分析,发现裂隙总水头损失、转折处局部水头损失与平均流速之间均呈二次函数关系,可用Forchheimer方程描述,且总水头损失、局部水头损失与平均流速之间函数关系的二次项系数随裂隙开度增大基本呈增大趋势,最终得到二次项系数分布的上包线与下包线,而一次项系数分布比较集中,总水头损失的一次项系数分布于-0.1～0.5之间,转折处局部水头损失的一次项系数分布于-0.1～0.25之间。
Fractures are the main part of karst systems.Fracture flow has a significant influence on the flow in the karst systems.The mechanism of fracture flow needs further researches.Based on the physical models of complex-single fractures with different turning angels and apertures,laboratory experiments are conducted to investigate the relationship between fractures hydraulic head loss and turning angels(varying from 0° to 165°)under different velocities(varying from 0 to 40 cm/s) and different apertures(1 to 2.5 mm).The curves of hydraulic head differences under the conditions with fractures and without fractures are obtained.Based on energy equations,the total hydraulic head losses calculation formula is obtained.Based on the verified Cubic Law and Darcy-Weisbach equation,the local hydraulic head losses are calculated,and the local hydraulichead losses are also obtained.The results show that both the total hydraulic head losses and the local hydraulic head losses increase with the increasing aperture and velocity.Using curve fitting,the relationship between the total hydraulic head loss and velocity is quadratic function and the relationship between the local hydraulic head loss and velocity is found to be expressed as a quadratic function,which can be depicted as the Forchheimer function.The quadratic term coefficients increase with the fracture aperture.In addition,the distributions of the quadratic term coefficients and the first term coefficients are obtained.The quadratic term coefficients occur between the upper envelope curve and the lower envelope curve.The first term coefficients of the total hydraulic head loss varies from-0.1 to 0.5,while the first term coefficients of the local hydraulic head loss varies from-0.1 to 0.25.
Fractures are the main part of karst systems.Fracture flow has a significant influence on the flow in the karst systems.The mechanism of fracture flow needs further researches.Based on the physical models of complex-single fractures with different turning angels and apertures,laboratory experiments are conducted to investigate the relationship between fractures hydraulic head loss and turning angels(varying from 0° to 165°)under different velocities(varying from 0 to 40 cm/s) and different apertures(1 to 2.5 mm).The curves of hydraulic head differences under the conditions with fractures and without fractures are obtained.Based on energy equations,the total hydraulic head losses calculation formula is obtained.Based on the verified Cubic Law and Darcy-Weisbach equation,the local hydraulic head losses are calculated,and the local hydraulichead losses are also obtained.The results show that both the total hydraulic head losses and the local hydraulic head losses increase with the increasing aperture and velocity.Using curve fitting,the relationship between the total hydraulic head loss and velocity is quadratic function and the relationship between the local hydraulic head loss and velocity is found to be expressed as a quadratic function,which can be depicted as the Forchheimer function.The quadratic term coefficients increase with the fracture aperture.In addition,the distributions of the quadratic term coefficients and the first term coefficients are obtained.The quadratic term coefficients occur between the upper envelope curve and the lower envelope curve.The first term coefficients of the total hydraulic head loss varies from-0.1 to 0.5,while the first term coefficients of the local hydraulic head loss varies from-0.1 to 0.25.
引文
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[2]王潇.单裂隙中粗糙元及其疏密度对水流特性影响模拟研究[D].合肥:合肥工业大学,2014.[WANG X.Simulation study on the effect of roughness element and its density on flow characteristics in a single fracture[D].Hefei:Hefei University of Technology,2014.(in Chinese)]
[3]尹乾.复杂受力状态下裂隙岩体渗透特性试验研究[D].徐州:中国矿业大学,2017.[YIN Q.Experimental study on hydraulic properties of fractured rock mass in complex stress state[D].Xuzhou:China University of Mining and Technology,2017.(in Chinese)]
[4]陈舟.交叉粗糙裂隙中水流与溶质运移试验研究[D].合肥:合肥工业大学,2007.[CHEN Z.Experimental study of water flow and solute transport in a cross fracture of roughness[D].Hefei:Hefei University of Technology,2007(in Chinese)]
[5]孙莉琴.粗糙单裂隙摩擦阻力与水流特性试验及模拟研究[D].合肥:合肥工业大学,2011.[SUNL Q.Experimental and simulation study of friction and characteristics of flow in a single rough fracture[D].Hefei:Hefei University of Technology,2011(in Chinese)]
[6]JAVADI M,SHARIFZADEH M,SHAHRIAR K,et al.Roughness effect on velocity distribution through rock fracture[J].Sharif University Civil Engineering Journal,2011:21-28.
[7]严小三,钱家忠,陈冰宇,等.大理石平板裂隙水运移实验与模拟研究[J].水动力学研究与进展A辑,2014(5):524-529.[YAN X S,QIAN J Z,CHEN B Y,et al.Experimental and simulated study of water flow and transport in a single fracture of marble parallel plates[J].Chinese Journal of Hydrodynamics(A),2014(5):524-529.(in Chinese)]
[8]束龙仓,张春艳,闵星,等.不同隙宽条件下L形裂隙水头损失试验[J].河海大学学报(自然科学版),2013(5):383-388.[SHU L C,ZHAGN CY,MIN X,et al.Experimental study on water head loss of L-shaped fractures with different aperture widths[J].Journal of Hohai University(Natural Sciences),2013(5):383-388.(in Chinese)]
[9]王熹,束龙仓,张春艳,等.平行裂隙沿程水头损失规律的实验研究[J].水文地质工程地质,2015,42(3):1-6.[WANG X,SHU L C,ZHANG C Y,et al.Experimental study of the law on hydraulic head loss in paralleled fractures[J].Hydrogeology&Engineering Geology,2015,42(3):1-6.]
[10]ZHANG C Y,SHU L C,LU C P,et al.Experimental determination of fractures and conduits and the applicability of Cubic law in closed fractures[J].Experimental Thermal&Fluid Science,2015,69(6):1-7.
[11]刘日成,蒋宇静,李树忱,等.交叉裂隙水力学开度的计算及非线性水力特性研究[J].岩土力学.2015,36(6):1581-1590.[LIU R C,JIANG Y J,LI S C,et al.Study of nonlinear hydraulic characteristics and hydraulic aperture calculation of crossed fracture[J].Rock and Soil Mechanics,2015,36(6):1581-1590.(in Chinese)]
[12]刘日成,李博,蒋宇静,等.三维交叉裂隙渗流特性的实验和数值模拟研究[J].岩石力学与工程学报.2016(增刊2):3813-3821.[LIU R C,LI B,JIANG Y J,et al.Experimental and numerical study on three-dimensional crossed fractures[J].Chinese Journal of Rock Mechanics and Engineering,2016(Sup2):3813-3821.(in Chinese)]
[13]桑盛,刘卫群,宋良,等.岩体交叉裂隙水流分配特性研究[J].实验力学,2016,31(5):577-583.[SANG S,LIU W Q,SONG L,et al.Study on the flow distribution characteristics of cross cracks in rock mass[J].Journal of Experimental Mechanics,2016,31(5):577-583.(in Chinese)]
[14]陈雷,王媛,牛玉龙.粗糙度与隙宽对单裂隙达西-非达西流演变规律的影响研究[J].河南科学.2017(12):1988-1994.[CHEN L,WANG Y,NIUY L.Influence of roughness and fracture width on the transition from Darcy to Non-Darcy behavior for flow through rough single fracture[J].Henan Science,2017(12):1988-1994.(in Chinese)]
[15]杨欢欢,王媛,高玮,等.宽隙比及粗糙度对交叉裂隙高速非达西偏流效应的影响[J].科学技术与工程.2018(7):44-49.[YANG H H,WANG Y,GAO W,et al.The effect of aperture ratio and roughness on the deflection of high-speed Non-Darcy seepage flow in intersection fractures[J].Science Technology and Engineering,2018(7):44-49.(in Chinese)]
[16]程勤波,陈喜,张志才,等.裂隙水流运动的入渗试验及数值模拟研究[J].水文地质工程地质,2018,45(4):7-14.[CHENG Q B,CHEN X,ZHANG Z C,et al.Fracture infiltration experiment and numerical simulation[J].Hydrogeology&Engineering Geology,2018,45(4):7-14.(in Chinese)]
[17]王礼恒,李国敏,董艳辉.裂隙介质水流与溶质运移数值模拟研究综述[J].水利水电科技进展,2013(4):84-88.[WANG L H,LI G M,DONG YH.Review of numerical simulation of flow and solute transport in fractured media[J].Advances in Science and Technology of Water Resources,2013(4):84-88.(in Chinese)]