第六届水利水电岩土力学与工程学术会议推荐论文

第六届中国水利水电岩土力学与工程学术会议推荐论文

无充填周期性裂缝岩体的等效渗透系数

舒付军，涂园，符文熹*

(四川大学水力学与山区河流保护国家重点实验室水利水电学院，四川成都 610065)

摘要：为了研究无充填周期性裂缝岩体的渗流特性，建立了地下水流动分析模型，该模型假定裂缝和岩石交界面流速相等且剪应力连续。根据分析模型的边界条件，耦合Navier−Stokes方程和Brinkman-extended Darcy方程，推求出裂缝和岩石中水流的流速分布。结合线性Darcy定律，推导出无充填周期性裂缝岩体沿裂缝方向等效渗透系数的理论表达，该表达式揭示裂缝开度对等效渗透系数起控制作用。为进一步验证理论模型推求的成果，研制试验装置开展渗流试验。试验时用浇筑混凝土模拟岩石，用混凝土间缝隙模拟岩石裂缝。测得的平均渗透系数和理论计算得到的等效渗透系数在同一量级，且相差很小。试验结果验证了所推求等效渗透系数表达式的正确性和可靠性。

关键词：无充填周期性裂缝；等效渗透系数；Navier−Stokes方程；Brinkman-extended Darcy方程；渗流试验

中图分类号：文献标识码：A

Equivalent Permeability Coefficient of Rock Mass Containing Periodic Fractures without Filling

SHU Fu-jun, TU Yuan, FU Wen-xi*

(State Key Lab. of Hydraulics and Mountain River Eng., School of Water Resource & Hydropower, Sichuan Univ., Chengdu 610065, China)

Abstract:In order to study the seepage characteristics of rock mass containing periodic fractures without filling,an analysis model for groundwater flow was built. In this model, two assumption conditions were given for the interface between rock and facture. One condition was that the velocity was equal and the other was that the shear stress was continuous.According to the given conditions,the velocity distribution in fractures was deduced using the Navier−Stokes equa tion and that in rocks was deduced using the Brinkman-extended Darcy equation. The equivalent permeability coefficient of the theoretic model, i.e. the rock mass containing periodic fractures without filling, was derived from the linear Darcy's law. The derived explicit equation shows that the aperture of fracture plays an important role in the groundwater flow in rock mass. In addition,the laboratory seepage tests were performed to validate this model. During the testing process, concrete and fracture between two pieces of concretes were used to simulate rock and fracture respectively. The average permeability coefficient value measured by tests and the equivalent value calculated from the theoretical expression were in the same order of magnitude, and the error was very small. The test results validate the expression given in this study.

Key words: periodic fractures without filling; equivalent permeability coefficient; Navier−Stokes equation; Brinkman-extended Darcy equation; seepage tests

受成岩作用、地质构造作用和浅表生地质作用等影响，天然岩体通常含有大量裂缝。岩体中的裂缝是地表水与地下水水力联系的重要通道，其渗流特性对研究裂缝岩体的水力特性具有重要的意义。单裂缝是构成岩体裂缝网络的基本元素，研究裂缝的渗流基本规律是岩体水力学的基本任务[1]。以平行平板间的粘性不可压缩层流为研究对象，假设边界条件为无滑移，可推导出开口立方定理[2]。然而，岩石裂缝通常难以满足平行平板间裂缝的假设。一些学者通过试验研究，对立方定理进行了修正，提出了修正后的立方定理[1]。文献[3]和[4]分别分析了渗流对单个裂缝岩体产生的力学作用和岩体单个裂缝的力学性质，并得出了裂缝所受的三维应力与渗透系数的关系式和粗糙单裂缝分形等效渗透系数的计算公式。文献[5]基于裂缝局域立

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基金项目：国家重点基础研究发展计划（973计划）项目（2015CB057903）；四川省科技计划专项（2014SS027）；国家级大学生创新创业训练计划（2）。作者简介：舒付军（1992–），男，硕士研究生。研究方向：岩石力学与工程。E-mail：。

*通信联系人：E-mail：。

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