摘要
裂隙渗透率的动态演化是工程岩体水力学特性中的一个关键科学问题,了解岩体渗透率动态演化机制,明确影响渗透率动态演化的机制,对工程设计和运行有重要意义。基于离散元和有限元方法,建立粗糙裂隙花岗岩的剪切渗流数值模拟,探究裂隙开度与渗透率在变围压条件下及剪切过程中的动态演化机制,揭示粗糙花岗岩裂隙渗透率在剪切过程中的动态演化规律。开展在1.9~20.0 MPa围压下粗糙裂隙样品的剪切和渗流过程数值模拟,监测粗糙裂隙样品的裂隙开度与渗透率演化行为。数值模拟与试验表现出相同的演化规律,剪切和围压对渗透率的演化有显著影响,围压的大小决定着渗透率的变化趋势。在1.9~10.0 MPa的围压条件下,岩石的渗透率先明显增大,然后在剪切作用后下降;当围压大于10.0 MPa时,裂隙渗透率仅呈下降趋势。剪切数值模拟结果显示,高围压限制了裂隙在剪切过程中的剪胀扩张现象,同时促进了岩石碎屑的形成,降低了裂隙的过水能力。系统提出了基于Barton公式的等效开度修正系数,并给出最终具有物理意义的渗透率计算方法;提出了裂隙等效开度和围压间的演化标准方程,在描述围压与不同裂隙等效开度之间演化关系时,能够较好地预测不同围压下初始、峰值和最小等效开度变化,进而用以计算渗透率。研究采用的剪切渗流数值计算方法为揭示裂隙渗透率动态演化机制提供了一种有效途径。
The dynamic evolution of fracture permeability is a critical issue in understanding the hydraulic characteristics of engineering rock masses.Investigating the dynamic evolution mechanisms of rock mass permeability is crucial for engineering design and operation,as it clarifies the factors influencing this process.Using the discrete element method and finite element method,this study establishes a numerical simulation framework for shear seepage in rough granite fractures to investigate the dynamic evolution of fracture aperture and permeability under varying confining pressures during shearing.The study reveals the dynamic evolution law of fracture permeability in rough granite during the shear process.Numerical simulations were conducted to analyze the shear and seepage processes of rough fracture samples under confining pressures ranging from 1.9 to 20.0 MPa,monitoring the evolution of fracture aperture and permeability.The numerical simulation results align with experimental observations,indicating that shear processes and confining pressure conditions significantly influence permeability evolution.Additionally,the magnitude of confining pressure determines the trend of permeability changes.Under confining pressures of 1.9–10.0 MPa,permeability initially increases significantly but decreases after shearing.When confining pressure exceeds 10.0 MPa,fracture permeability exhibits a downward trend throughout.Shear numerical simulations reveal that high confining pressures restrict fracture shear expansion,promote rock debris formation,and reduce the fracture’s water-carrying capacity.This study systematically proposes an equivalent aperture correction coefficient based on the Barton formula,provides a physically meaningful permeability calculation method,and establishes a standard evolution equation linking fracture equivalent aperture and effective confining pressure.These formulations enable accurate predictions of initial,peak,and minimum equivalent apertures under varying confining pressures and facilitate permeability calculations.The shear seepage numerical simulation method offers an effective approach to elucidate the dynamic evolution mechanisms of fracture permeability.
作者
李槟
申海萌
李琦
李霞颖
LI Bin;SHEN Hai-meng;LI Qi;LI Xia-ying(State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《岩土力学》
北大核心
2025年第S1期437-453,共17页
Rock and Soil Mechanics
基金
国家自然科学基金联合基金重点项目(No.U23A20671)
关键词
裂隙
围压
渗透率
开度
数值计算
fracture
confining pressure
permeability
aperture
numerical simulation
