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| 1 | MRT-LBM-based numerical simulation of seepage flow through fractal fracture networks显示文摘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. | FAN Huo ZHENG Hong | 2013 | Science China(Technological Sciences)2013，56，12： | 12 |
| 2 | A new variational inequality formulation for unconfined seepage flow through fracture networks显示文摘Darcy's law only applying to the flow domain is extended to the entire fracture network domain including the dry domain.The partial differential equation(PDE) formulation for unconfined seepage flow problems for discrete fracture network is established,in which a boundary condition of Signorini's type is prescribed over the potential seepage surfaces.In order to reduce the difficulty in selecting trial functions,a new variational inequality formulation is presented and mathematically proved to be equivalent to the PDE formulation.The numerical procedure based on the VI formulation is proposed and the corresponding algorithm has been developed.Since a continuous penalized Heaviside function is introduced to replace a jump function in finite element analysis,oscillation of numerical integration for facture elements cut by the free surface is eliminated and stability of numerical solution is assured.The numerical results from two typical examples demonstrate,on the one hand the effectiveness and robustness of the proposed method,and on the other hand the capability of predicting main seepage pathways in fractured rocks and flow rates out of the drainage system,which is very important for performance assessments and design optimization of complex drainage system. | JIANG QingHui YE ZuYang YAO Chi ZHOU ChuangBing | 2012 | Science China(Technological Sciences)2012，55，11： | 11 |
| 3 | 某抽水蓄能电站上水库防渗帷幕深度优选研究显示文摘针对某抽水蓄能电站上水库地质条件较为复杂、库区存在两条由库内延伸到库外的中等宽度断层、副坝区基岩弱风化层较厚的特点,以及设计防渗方案不合理的问题,根据上库工程坝址区的地质结构、地形地貌及防渗帷幕设计,建立了三维有限元渗流分析模型。首先通过参数及地下水位反演确定了库区基岩的渗透系数和水库特征点处的地下水位,然后在设计防渗方案的基础上计算分析了不同防渗帷幕深度对库区渗流场、渗透流量及各部位渗透坡降的影响,并根据分析结果对防渗帷幕深度进行了方案优选。结果表明:河床断层附近和库周断层及副坝附近的防渗帷幕深度可增大10 m,左、右坝肩帷幕深度可分别减少10 m并降低至3 Lu标准,库周非断层及副坝附近的防渗帷幕深度可减少10 m。研究结果可为类似工程防渗帷幕深度方案的优选提供参考。 | 杨金孟 赵兰浩 沈振中 甘磊 徐力群 | 2021 | 水资源与水工程学报2021，32，2： | 11 |
| 4 | 基于MRT-LBM的分形裂隙网络渗流数值模拟显示文摘单一裂隙渗流规律的研究是岩体裂隙网络渗流规律及渗流场与应力场耦合作用研究的基础和关键.由分形插值算法重构天然粗糙裂隙面,用Lattice Boltzmann方法的MRT-LBM模型,在岩石粗糙裂隙表面微观结构的层次上,对两种具有不同垂直比例因子的粗糙裂隙面进行了数值模拟,得到优势渗流路径长度后,预估了渗透率.针对难以找到优势渗流路径的天然裂隙网络,在数值试验的背景下,提出了一个新的预估渗透率的截面渗透率加权法.该算法不具体针对某条优势路径或某些较优势路径,而是考虑每个截面对阻碍流体通过的贡献.接着对两组基于图像处理的天然裂隙网络进行了数值模拟,预估了各自的渗透率并再现了偏流现象,发现优势渗流路径在演化初期已具雏形,以后逐渐被强化.此外,使用该方法可以清楚地观察到渗流网络中的局部流体流动细节,局部分支路径回流和局部漩涡可能同时存在.证明了该方法的有效性,并为后期的跨尺度渗流模拟奠定基础. | 樊火 郑宏 | 2013 | 中国科学:技术科学2013，43，12： | 8 |
| 5 | Research advance in failure risk and local strength failure for high arch dams显示文摘To develop national economy and use the water resources and hydropower resources sufficiently,a lot of high arch dams,with the height of more than 200 m,have been and will be built in China.Although arch dams have good mechanical behavior,there is still failure possibility due to the huge water pressure and high stress level in dam,complex topographic and geologic conditions,formidable environment and high intensity earthquake.As one of the three main aspects concerning the safety of high arch dam,the study on global destruction,has been elaborated in the literatures,and research advance in the other two aspects,namely the failure risk and local damage of high arch dams,will be reviewed in this paper.In recent years,the failure risk of high arch dams has been investigated,and the model for identifying dam failure risk factors has been established.It is shown that the foundation deterioration and strong earthquake are the major risk sources for high dam failure.With the fault tree method,the failure mode and failure probability of high arch dams are studied,and the principle for determining failure mode and the method of calculating failure probability are proposed.Meanwhile,the determination principle of acceptable risk standard for high arch dam was proposed,and the acceptable risk rate and the acceptable standard value of various risk losses were given.For the local damage of arch dam,it is pointed out that the local damage belongs to the strength failure at material level.The study on local failure mechanism of arch dam is reviewed,based on the theories that from traditional strength theory to damage mechanics and meso-mechanics theory.Aiming at the cracking,the main pattern of local failure of high concrete dam,the research advances in the analysis methods and cracking criteria for smeared crack model and discrete crack model are summarized,and the research findings of preventive measures for local failure are shown. | REN QingWen LI Qiang LIU Shuang | 2012 | Chinese Science Bulletin2012，57，36： | 5 |
| 6 | Study on coupled 3D seepage and stress fields of the complex channel project显示文摘Seepage is a vital reason that may bring many adverse consequences such as subsidence,inclination and fracture to the channel,and is harmful to the safety and stability of the channel.Thus,a 3D visualization model is established for the engineering geological information of the research channel section by using NURBS-TIN-BRep hybrid data structure.Coupled with the VOF(volume of fluid)method,the N-S(Navier-Stokes)equations are applied to seepage simulation of the research channel section.Then the stability of the channel is studied coupled with the seepage simulation results,to comprehensively analyze the stress and displacement conditions of the channel under the impact of different factors such as seepage and underground goafs.The results of this study illustrate that the channel seepage has great influence on its stability,especially on the displacement field:it will lead to a significant sedimentation to the foundation.Therefore,during the practical construction,it is suggested that the certain part of the channel should be reinforced and effective seepage control measures should be taken. | ZHONG DengHua ZHANG XiaoXin AO XueFei WANG XiaoLing TONG DaWei REN BingYu | 2013 | Science China(Technological Sciences)2013，56，8： | 5 |
| 7 | The variational inequality formulation for unconfined seepage through three-dimensional dense fracture networks显示文摘The space block search technology is used to determine a connected three-dimensional fracture network in polygonal shapes,i.e.,seepage paths.After triangulation on these polygons,a finite element mesh for 3D fracture network seepage is obtained.Through introduction of the generalized Darcy's law,conservative equations for both fracture surface and fracture interactions are established.Combined with the boundary condition of Signorini's type,a partial differential equation(PDE) formulation is presented for the whole domain concerned.To solve this problem efficiently,an equivalent variational inequality(VI) formulation is given.With the penalized Heaviside function,a finite element procedure for unconfined seepage problem in 3D fracture network is developed.Through an example in a homogeneous rectangular dam,validity of the algorithm is verified.The analysis of an unconfined seepage problem in a complex fracture network shows that the proposed algorithm is very applicable to complex three-dimensional problems,and is effective in describing some interesting phenomenon usually encountered in practice,such as 'preferential flow'. | YAO Chi JIANG QingHui WEI Wei ZHOU ChuangBing | 2013 | Science China(Technological Sciences)2013，56，5： | 5 |
| 8 | Towards an optimization design of seepage control:A case study in dam engineering显示文摘High dams generally suffer from higher seepage risks in their foundations, and seepage control is an important technology for limiting the amount of leakage and improving the stability of the foundations. In this study, a procedure was proposed for optimization design of seepage control system in large-scale hydropower projects, which relies on sufficient characterization of site conditions and proper quantification of the performance of the seepage control system. The proposed procedure was applied to the design of seepage control system in the Mengdigou Hydropower Station consisting of a double-curvature arch dam201 m in height. An optimized layout of the seepage control system, including the extended length of grout curtain, the rows of grouting holes and the spacing of drainage holes, was suggested. The proposed procedure provides a guide with lower risk and higher confidence for performance assessment and optimization design of seepage control systems in high dam engineering. | LI Xing CHEN YiFeng HU Ran YANG ZhiBing | 2017 | Science China(Technological Sciences)2017，60，12： | 3 |
| 9 | 复杂渠道工程三维渗流应力耦合分析与研究显示文摘渗流是导致渠道下沉、倾斜、断裂等诸多不良后果的重要因素,对渠道安全稳定运行危害较大.基于NURBS-TIN-BRep混合数据结构,构建南水北调中线工程某渠段的工程地质信息三维可视化模型,运用耦合VOF(volume of fluid,流体体积函数)法的N-S(NavierStokes)方程,对研究区域进行渗流模拟,并采用流固耦合进行渠道稳定性计算,全面分析渠道在渗漏、下伏采空区等多种因素影响下的应力及位移状态.结果表明:渠道渗流对其稳定性影响较大,特别是对位移场的影响较为明显,渠道渗流将导致其自身产生相对较大的沉降,因此建议在实际施工过程中进行渠道的局部加固,并采取有效地渗流控制措施. | 钟登华 张晓昕 敖雪菲 王晓玲 佟大威 任炳昱 | 2013 | 中国科学:技术科学2013，43，11： | 3 |
| 10 | 复杂裂隙网络无压渗流分析的变分不等式提法显示文摘通过对仅适用于湿区裂隙渗流的Darcy定理进行延拓处理,并将潜在溢出面归纳为Signorini型互补边界条件,建立了定义在裂隙网络全域上无压渗流问题的偏微分方程(PDE)提法.为了减小试探函数的选取难度和消除溢出点的奇异性,进一步发展了与PDE提法等价的变分不等式(VI)提法,并给出了离散型变分不等式提法的有限元数值求解格式、迭代算法与计算流程.由于使用了连续型的Heaviside函数代替阶跃型函数,避免了对位于过渡区域裂隙单元进行积分时形成的数值跳跃,从而显著提高了有限元数值求解过程中的稳定性.典型算例的计算结果验证了该方法的有效性和可靠性,并表明基于离散裂隙网络模型的无压渗流分析不但可以较好模拟裂隙岩体渗流的非均质性和优势水流方向,还可以准确预测坡体内部排水结构的渗流量,为裂隙岩体边坡防渗排水系统的优化布置提供科学依据. | 姜清辉 叶祖洋 姚池 周创兵 | 2012 | 中国科学:技术科学2012，42，11： | 3 |
| 11 | 三维密集裂隙网络无压渗流模拟的变分不等式提法显示文摘利用全空间块体搜索技术获得三维裂隙网络的渗流路径并将其三角化,得到用于三维裂隙网络渗流计算的有限元网格.引入广义Darcy定理,建立了全域上三维裂隙网络裂隙面和裂隙交界处的渗流基本方程,结合Signorini型边界条件,给出了全域上的渗流偏微分方程(PDE)提法.为方便离散求解,提出了一个与之等效的变分不等式(VI)提法,并利用格林公式展开,证明了它们的等效性.结合罚Heaviside函数,建立了三维裂隙网络无压渗流问题的有限元求解格式,并编制了相应的程序.通过与均质矩形坝算例的对比,验证了算法的合理性.对空间复杂裂隙网络的无压渗流问题的计算表明,所提算法对复杂三维问题具有很强的适用性,并能很好的刻画三维裂隙渗流问题诸如'优势流'等明显特征. | 姚池 姜清辉 位伟 周创兵 | 2013 | 中国科学:技术科学2013，43，7： | 1 |
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