各向异性裂隙岩体渗透系数计算方法探讨

针对岩体裂隙系统提出了计算各向异性渗透系数的方法，给出了使用有限差分法计算各向异性渗透系数的数值方法和差分单元渗透性的计算公式，并以实际裂隙网络系统资料为基础进行了该方法的应用探讨。该方法可以在已知裂隙网络的基础之上计算岩体的各向异性渗透系数，通过加密剖分网，它可以更好地消除裂隙非贯通性的影响，并可以处理裂隙充填等问题，此外还可以分析裂隙岩体渗透性随测量窗口尺度小的变化，并进行其连续介质性质检查。     

有效应力作用下单裂隙渗透规律的实验研究

通过对单裂隙试件进行的渗透性实验，提出了考虑岩石物性参数的渗透系数表达式，并根据实验结果建立了在有效应力作用下裂隙闭合量Δｂ与渗透系数ｋｆ和有效应力σｃ的关系式。这对深入研究裂隙渗流，简化有限元计算，解决工程实际问题具有一定的指导意义。     

用弹性波速计算正交各向异性岩体的裂隙张量

初步尝试了运用弹性波速确定岩体的裂隙张量;首先将岩体视为正交各向异性介质,基于裂隙岩体的应变体积平均,从裂隙引起的间断位移出发,导出裂隙张量与由裂隙引起的柔度张量增量之间的关系;然后根据正交各向异性岩体的波动理论,建立了岩体裂隙张量、等效弹性参数和弹性波速三者之间的相关关系。根据这些关系,给出了二阶、四阶裂隙张量的弹性波速计算过程。含裂缝水泥砂浆试件的试验结果表明,采用本文计算方法获得的裂隙张量基本能反映出裂隙的分布情况。     

岩体裂隙非饱和渗流试验系统研制及应用

摘　要: 为了准确测定岩体裂隙非饱和水力参数, 并揭示裂隙非饱和渗流特性及规律, 设计研发了一套裂隙非饱和渗流试验系统。该系统不仅可以实现真正意义上的岩体裂隙非饱和渗流, 而且使用高精密的柱塞泵、 电子天平、 压力传感器和回压控制系统等, 可确保试验的测量和控制精度。通过开展岩体单裂隙非饱和渗流试验, 初步阐明了单裂隙非饱和渗流的一些水力特性: 实际岩体裂隙相对于概化模型裂隙具有更大的束缚水饱和度, 而且由于薄膜水和孔角毛细水的存在, 当饱和度很低时, 非饱和渗透系数也较概化模型裂隙大。建立了毛细压力与非饱和渗透系数之间的试验关系, 通过对试验数据的分析提出了毛细压力-非饱和渗透系数的拟合公式, 根据与前人所建立的经验公式对裂隙吸水和排水过程拟合结果的对比可知, 本文公式的拟合精度高, 对于深入研究裂隙非饱和渗流具有一定的参考价值, 同时, 试验结果表明本文试验系统是准确可靠的, 可用于岩体裂隙非饱和水力参数的测定及非饱和渗流特性的研究。     

裂隙岩体渗流场与应力场耦合数学模型的研究

首先研究裂隙岩体中应力场改变对地下水渗流场的影响作用机理,推导出渗透系数k和给水度μ受应力影响的表达式,进而分析渗流场的变化,地下水的作用引起应力场环境变迁,导致裂隙岩体的渗透变形,在此基础上建立了裂隙岩体中应力场与渗流场耦合作用研究工作程式和具"点荷载"特征的等效连续介质耦合数学模型,并应用于一隧道工程实例进行了计算.     

节理岩体损伤模型有限元分析

将岩体中固有的初始节理损伤考虑成宏观损伤场，通过引入损伤张量模拟岩体的多裂隙性。损伤张量由节理组的实测数据确定，并引入有效应力来计算节理岩体的力学效应。编制了损伤模型的平面非线性有限元程序，并采用损伤模型和常规有限元模型的有限元程序对某矿山边坡进行对比计算分析。结果表明，损伤模型有限元解析能反映节理岩体的各向异性。     

岩体分形裂隙网络系统中水流动研究进展

以分形几何理论和岩体裂隙系统统计地质资料为基础,建立描述岩体裂隙网络系统几何特性的分形模型.考虑到裂隙长度、开度、位置和间距等几何参量的分形特性,建立基于Monte-Carlo模拟的岩体的裂隙网络系统模型随机生成方法.回顾了岩体裂隙网络系统几何参数的分形分布模型以及离散分形裂隙网络系统建模方法、单个裂隙以及裂隙系统水流动数值模拟方法和裂隙系统等效渗透系数估计方法.对岩体裂隙网络系统的分形几何结构进行研究,使得裂隙网络几何模型真实反映岩体裂隙的结构特征、水流动和溶质传输数值模拟模型更接近岩土工程实际原型、预测结果更加准确,在物理本质上揭示分形裂隙岩体水流动和溶质传输机理.     

三维非均质岩体各向异性渗流场分析

通过对天生桥一级水电站引水系统非均质各向异性岩体渗流场的模拟计算，提出了三维非均质岩体各向异性渗流场的计算方法，并导出三维排水廊道边界的计算公式和三维自由水面边界的迭代方法．通过对不同参数对渗流场影响的研究和各种运行工况三维渗流场特征的分析，得出了三维各向异性渗流场的一些基本规律，为高压引水管道的设计、施工提供了合理的设计依据．     

裂隙岩体温度-渗流耦合数值流形方法研究(研究生论坛)

在建立岩体裂隙岩体温度-渗流耦合微分控制方程的基础上,基于裂隙网络渗流理论和数值流形理论,通过分析考虑裂隙作用的温度场和流形覆盖与裂隙网络的关系,以裂隙网络节点水头、覆盖温度函数为求解量,提出了裂隙岩体温度-渗流耦合的数值流形方法。该方法利用数值流形理论中网格、覆盖及流形单元的关系,可以在同一数学网格下实现了对温度-渗流耦合场的迭代求解。由于渗流裂隙网络必定会与材料边界相交,所以数学网格不受边界及裂隙限制,能够有效的避免常规方法中裂隙处网格划分问题,因此该方法特别适合于模拟裂隙岩体的耦合问题。最后,运用该模型对部分算例进行了计算,验证了方法的正确性。     

复合形优化方法在石刻岩体渗流反演分析中的应用

岩体渗流反演分析可利用最优化方法来寻找一组反映客观岩体渗流的参数,其实质是求解带约束的最优化问题,而复合形是解决带约束条件的非线性规划问题的—种比较简单、且易于实现的优化方法,文章介绍了将它与岩体渗流有限元数值分析相结合的岩体渗流反演方法的基本原理及过程,并利用这种方法在大足县顶山石刻岩体渗流中得到应用。通过反演分析表明,宝顶山石刻区上层渗流介质的渗透系数为1.0014m d,降雨入渗量为1.0988×10-4m d,下层渗流介质的水平向渗透系数为44.994m d,竖向渗透系数为2.9472m d,具有明显的各向异性,计算结果符合实际。     

管单元用于缩减岩体渗透张量计算规模

为探讨裂隙空间渗流的优势路径、在满足精度的前提下减少计算量并使模型更具实用价值,根据实测结构面资料,采用圆盘模型,生成与现场岩体具有相同统计特征的三维裂隙网络,将渗流渠道简化为一维管单元模型,研究分组排列和全排列两种方式缩减计算规模对渗透张量和表征单元体(representative elementary volume...     

碳酸盐岩潜山储层渗透率解释方法探讨

碳酸盐岩储集层的非均质性非常严重,大多数具有多重孔隙结构特征,渗透率为岩块渗透率和裂缝渗透率的总和,计算比较复杂。我们充分利用常规测井资料及核磁测井技术对潜山裂缝性油藏储集层进行深入系统的研究,总结出了一套全面系统的评价渗透率的解释方法,极大地提高了碳酸盐岩潜山裂缝性储层渗透率的解释精度。     

无充填周期性裂缝岩体的等效渗透系数（稿件编号：201600412）

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。     

压裂压后裂缝闭合模型及其应用

综合运用流体力学和岩石力学的相关理论以及物质平衡原理,建立压裂压后裂缝闭合模型.通过模型求解分析裂缝闭合过程中井口压力的变化规律,给出裂缝闭合时间和支撑剂沉降距离的计算方法.实例分析和应用表明,低渗透储层人工裂缝自然闭合时间过长,支撑剂沉降距离较大,导致压裂液对地层和裂缝的污染严重,最终影响压裂效果,因此,压裂压后合理选择液体返排时机非常重要.     

Study on implicit composite element method for seepage analysis in underground engineering

Based on the basic principle of the finite element method, the implicit composite element method for numerical simulation of seepage in underground engineering is proposed. In the simulation, the faults and drainage holes are set implicitly in the model elements without adding additional elements. Elements containing fault or drainage-hole data are termed composite elements. Then, their information data in model could be obtained. By determining the osmotic transmission matrix of the composite elements, the permeability coefficient matrix is then obtained. The method was applied to the numerical simulation of the seepage field around the underground powerhouse of the Ganhe Pumping Station in Yunnan, China, using a compiled three-dimensional finite element method calculation program. The rock mass around the site includes two faults. The seepage field in the rock mass was analyzed at different stages of the engineering project. The results show that, before the excavation of the underground caverns, the rock mass seepage is affected by the faults and the groundwater permeated down along the tangential fault plane. After the excavation of the caverns during the operation period, the groundwater is basically drained away and the underground caverns are mostly above the groundwater level. Thus, the calculation results of the engineering example verify the implicit composite method for the simulation of faults and drainage holes. This method can well meet the calculation demands of practical engineering.     

MRT-LBM-based numerical simulation of seepage flow through fractal fracture networks

The study on seepage flow passing through single fractures is essential and critical for understanding of the law of seepage flow passing through fracture networks and the coupling mechanisms of seepage field and stress field in rock masses. By using the fractal interpolation to reconstruct a natural coarse fracture, as well as taking into account the microstructure of the fracture, the numerical simulation of seepage flow passing through the coarse fractures with two distinct vertical scaling factors is conducted based on the MRT-LBM model of the lattice Boltzmann method. Then, after obtaining the length of the preferential flow pathway, the permeability of the two kinds of fractures is estimated respectively. In view of difficulties in locating the preferential flow pathway of natural fracture networks, by numerical tests a transect permeability weighted algorithm for estimating the fracture network permeability is proposed. The algorithm is not specific to one or more particular preferential flow pathways, but considers the contribution of each section to hinder the fluid passing through the medium. In order to apply the new algorithm, by capturing the structure of fracture networks based on the image-processing technique, the numerical simulations of seepage flow passing through two groups of natural fracture networks is carried out, the permeability is forecasted and the partial flows are reproduced for both cases. It is found that the preferential flow pathway emerges at the beginning of evolution, then is strengthened subsequently, and finally reaches a steady status. Furthermore, by using the proposed method some details on local flow can be clearly observed such as backflows and vortices at local branches can exist simultaneously and so forth, suggesting the validness of the proposed method for multiscale simulations of seepage flow.     

破碎围岩锚注加固浆液扩散规律研究

基于连续介质力学和渗流力学理论,运用渗透张量法得出浆液在破碎围岩中扩散的基本方程;并通过对实际锚注支护工程进行假设与简化,建立锚注加固系统浆液在包含正交裂隙组的围岩中渗透扩散的数学模型.在此基础上,运用COMSOL软件对锚注支护工程进行实时模拟,研究了不同注浆压力和不同注浆锚杆布置方式对浆液流动扩散规律的影响.结果表明：对于巷道锚注支护工程,合理的注浆压力约为1.0～4.0MPa,合理的钻孔间距约为浆液扩散半径的1.3倍左右.将研究成果用于祁南煤矿新掘大巷锚注支护设计,取得了良好的效果.     

饱和岩石各向异性弹塑性损伤模拟

自然界岩石是各向异性的,其破坏性也是非均匀的,岩石各向异性力学特性研究非常必要.提出了一种弹塑性破坏模型,该模型可以描述弹性变性、损伤不可逆变形和塑性变形,以二阶张量来描述损伤的扩展,损伤演化相关于微裂纹扩展标准.并以应变自由能获得有效弹性刚度矩阵,推导出了损伤参数限制范围,提出了以室内试验决定损伤参数的相应表达式.模拟了不同加载路径情况下的岩石力学行为,数值结果和试验结果较为一致.该模型被推广应用于不同加载路径的岩石水力学行为的模拟之中,数值结果显示该模型能模拟岩石孔隙水力学基本特征.     

Finite element analysis for inclined wellbore stability of transversely iso-tropic rock with HMCD coupling based on weak plane strength criterion

The finite element analysis (FEA) technology by hydraulic-mechanical-chemical-damage (HMCD) coupling is proposed in this paper for inclined wellbore stability analysis of water-sensitive and laminated rock, developed basing on the recently established FEA technology for transversely isotropic rock with hydraulic-mechanical-damage (HMD) coupling. The chemical activity of the drilling fluid is considered as phenomenological hydration behavior, the moisture content and parameters of rock considering hydration could be determined with time. The finite element (FE) solutions of numerical wellbore model considering the chemical activity of drilling fluid, damage tensor calculation and weak plane strength criterion for transversely isotropic rock are developed for researching the wellbore failure characteristics and computing the time-dependent collapse and fracture pressure of laminated rock as shale reservoirs. A three-dimensional FE model and elastic solid deformation and seepage flow coupled equations are developed, and the damage tensor calculation technology for transversely isotropic rock are realized by introducing effect of the hydration and the stress state under the current load. The proposed method utilizing weak plane strength criterion fully reflects the strength parameters in rock matrix and weak plane. To the end, an effective and reliable numerically three-step FEA strategy is well established for wellbore stability analysis. Numerical examples are given to show that the proposed method can establish efficient and applicable FE model and be suitable for analyzing the timedependent solutions of pore pressure and stresses, and the evolution region considering the hydration surrounding wellbore, furthermore to compute the collapse cycling time and the safe mud weight for collapse and fracture pressure of transversely isotropic rock.