饱和岩石的动态渗透率和动电耦合系数解析式          下载免费PDF全文

时鹏  关威  王军 《地球物理学报》2020,63(4):1695-1704

动态渗透率和动电耦合系数是描述岩石中渗流波动和弹性-电磁耦合波效应的重要参数.本文基于毛细管束模型,提出了流体饱和孔隙介质的动态渗透率和动电耦合系数的解析表达式和简化表达式,并通过与前人近似式结果的对比,分析了不同表达式的合理性和适用性.在此基础上,理论分析了孔隙几何形状和孔径分布对渗透率和动电耦合系数的频率响应以及井孔震电耦合波场的影响.研究结果表明:当认为孔道均匀且达西渗透率、孔隙度和弯曲度恒定时,孔隙几何形状的影响很小,可以忽略,而前人的近似式高估了孔隙几何形状的影响;孔径分布的影响显著,随着孔径分布的增大,渗透率的临界频率显著减小,动电耦合系数的临界频率显著增加,震电测井的斯通利波及其伴随电场幅度显著增大.  相似文献   

Urbanization and eco-environment coupling circle theory and coupler regulation     

Fang  Chuanglin  Cui  Xuegang  Deng  Xiangzheng  Liang  Longwu 《地理学报(英文版)》2020,30(7):1043-1059

A near-distance, nonlinear coupling relationship objectively exists between urbanization and the eco-environment. The issue of how to coordinate the relationship between them has become a global strategic and scientific issue. This study reveals the nature, relationship and intensity of coupling between urbanization and the eco-environment from a theoretical perspective. Based on the strength of coupling, relationships can be characterized as having very-low, low, medium, high, very-high or full coupling intensity, which correspond to the categories of random coupling, indirect coupling, loose coupling, cooperative coupling, close coupling, and controlled coupling. Together, these make up an urbanization and eco-environment "coupling tower." This study also develops an urbanization and eco-environment coupling circle theory and generates 45 coupling graphs(including linear, exponential-curve, logarithmic-curve, double exponential-curve and S-curve graphs) per 10° of rotation of the coupling circle, with different graphs corresponding to different urban development stages and development models. Of the various coupling graphs, the S-curve graph is considered the optimum, as it reflects the best interactivity scenario between urbanization and the eco-environment. Using an S-curve coupling graph, and with the help of an SD model and based on the complex one-to-one, one-to-many, and many-to-many relationships between the variables, this study develops the Urbanization and Eco-environment Coupler(UEC). The UEC is composed of 11 regulating elements and 201 variables. If one variable changes, it changes the whole, affecting the structure, function and regulation of the entire coupler. The UEC includes three spatio-temporal scales: static regulation between multiple urbanization areas and eco-environment areas at the same time, dynamic regulation between the same urbanization area and eco-environment area at different times, and dynamic regulation between multiple urbanization areas and eco-environment areas at different times. Regulation gradually promotes evolution from low-level coupling to high-level coupling between urbanization and the eco-environment.  相似文献   

Spatio-temporal patterns of the interaction between groundwater and surface water in plains     

Cristian Guevara Ochoa  Agustín Medina Sierra  Luis Vives  Erik Zimmermann  Ryan Bailey 《水文研究》2020,34(6):1371-1392

The study of the dynamics of anthropic disturbances that have an effect on the hydrological systems in plains requires integral simulation tools for their diagnosis. The objective of this article is, first, to analyse and reproduce the spatio-temporal interactions between groundwater (GW) and surface water, net recharge, GW level, surface run-off, and evapotranspiration in the upper creek basin of Del Azul, which is located in the centre of the province of Buenos Aires, Argentina, and second, to obtain insights to apply the methodology to other similar situations. For this purpose, a model coupling the semidistributed hydrological model (Soil and Water Assessment Tool [SWAT]) and the hydrogeological model (MODFLOW) has been used. A simulation was carried out for a period of 13 years (2003–2015) on a daily scale. The application of the SWAT–MODFLOW coupling gave good results based on the adjustment between the calculated flows and levels, reaching a Nash–Sutcliffe of 0.6 and R²0.6 at the Seminario hydrometric station located at the watershed outlet point. According to the annual average balance, out of the total rainfall, evapotranspiration accounts for 85%, recharge accounts for 10.2%, and surface run-off accounts for 4.8%. Annual and monthly trends of the stream–aquifer interaction were determined, obtaining on average an annual GW discharge of 34 mm and an annual average recharge of the stream to the aquifer of 1.4 mm. Monthly GW discharges are higher in winter–spring (July to December with an average of 3.3 mm) and lower in summer–autumn (January to June with an average of 2.8 mm). The monthly average recharge of the stream towards the aquifer varies from 0.02 to 0.36 mm and is higher in March, May, and August, when water excess is produced in the basin. Through the analysis of coupled modelling, it is possible to analyse and reproduce the spatio-temporal transitions of flow existing between the stream, the hyporheic zone, and the aquifer.  相似文献   

Polymetamorphism in high‐T metamorphic rocks: An example from the central Appalachians     

Kirkland S. Broadwell  Mark J. Caddick  James S. Beard 《Journal of Metamorphic Geology》2019,37(9):1209-1234

Contact metamorphism associated with mafic intrusives is one of several mechanisms that has been invoked to produce extensive high‐temperature (HT) metamorphism and associated partial melting of the crust. Indisputable evidence for polymetamorphism in these settings can be difficult to decipher because both melt loss and retrogression (i.e. rehydration) can erase or obscure the records of earlier HT metamorphism by modifying HT mineral parageneses and compositions. Here, a combination of detailed field and petrographical observations, inverse mineral thermometry, and thermodynamic forward modelling is used to delineate the polymetamorphic history of migmatites from the Smith River Allochthon (SRA) in the central Appalachians. Bulk rock geochemical data suggest that some metapelitic samples lost a significant amount of melt during interpreted contact metamorphism with the Rich Acres gabbro, resulting in a residual bulk composition (<50 wt% SiO₂, ~30 wt% Al₂O₃). Garnet cores (Grt1) in SiO₂‐depleted samples are interpreted to grow during this HT contact metamorphism, with Fe‐Ti oxide thermometry on spinel inclusions in Grt1, cordierite–garnet thermometry, and thermodynamic forward modelling constraining peak P–T conditions during contact heating of the migmatites to ~800ºC and ～0.5 GPa. This is associated with an inferred peak assemblage prior to melt loss of crd+kfs+pl+grt+bt+spl (mag+usp+hc)+ilm+sil+qtz+melt. Garnet in SiO₂‐depleted samples has a distinct high‐Ca rim (Grt2), which appears to record a younger metamorphic event. A combination of substantial melt loss and later rehydration appears to be a major control on the ability of SiO₂‐depleted samples to faithfully record evidence for this polymetamorphism. The tectonic implications of this younger metamorphic event are not entirely clear, but it appears to record renewed burial and heating of the SRA sometime after the Taconic orogeny, which may be related to either the neo‐Acadian or Alleghanian orogenies.  相似文献   

深水顶张式立管全耦合动力响应及参数敏感性分析     

罗坤洪  黄维平  常爽  柳振海 《海洋工程》2019,37(1):108-116

通过建立双套管与油管的全耦合运动控制方程,使用Newmark-β法,运用Matlab软件进行编程,对模型进行非线性时域动力耦合响应分析,分析在一定波浪环境,不同扶正器布置间距下,立管各层相同节点处耦合动力响应,研究各层管之间发生碰撞和摩擦的最大扶正器布置间距;分析相同扶正器布置间距下,不同顶张力系数对耦合动力响应的影响。结果表明:在波浪作用下,全耦合动力响应分析比等效管更能展现各层管的实际动力响应;扶正器布置间距与顶张力系数的取值不同,会影响各层立管的耦合响应与相对位移,取值不当时,立管会发生碰撞。  相似文献   

耦合有限单元法扩边的直流电阻率勘探无单元Galerkin法正演          下载免费PDF全文

麻昌英  柳建新  郭荣文  孙娅  崔益安  刘嵘  刘海飞 《地球物理学报》2018,61(6):2578-2588

本文分析了目前直流电阻率正演模拟中的无单元Galerkin法（EFGM）和有限单元法（FEM）的优缺点，针对采用第一类边界条件需要足够大的计算域时EFGM计算成本高的问题，在计算域外围区域采用FEM扩边，提出了直流电阻率的无单元Galerkin-有限单元耦合法（EFG-FE）.采用具有Kronecker delta函数性质的径向基点插值法（RPIM）构造EFGM形函数，在外围区域将EFGM与FEM直接耦合，无需其他处理手段，消除了传统EFGM与FEM耦合中存在的界面耦合困难.EFG-FE将模型计算域分割为EFGM区域和FEM区域，模型核心区域采用EFGM计算，发挥EFGM灵活性、适应性强和高精度的优点，使得模型建立简单方便，对任意复杂地电模型适应性强，同时获得高精度模拟结果.在模型计算域外围采用快速扩展的FEM单元网格进行剖分，利用其数值稳定性和高效性，使用少量FEM节点和单元网格将计算域大范围扩大满足第一类边界条件，同时不大幅增加计算成本，进而提高计算效率.最后，通过不同正演方法的模型算例的模拟结果对比，验证了本文提出的EFG-FE有效可行，其模拟结果具有很高的模拟精度，且相比于采用第三类边界条件的EFGM提高了计算效率，具有更好的模拟性能.  相似文献   

带有可更换连梁的钢筋混凝土结构设计方法          下载免费PDF全文

陈聪  吕西林  姜淳 《世界地震工程》2018,34(2):010-25

钢筋混凝土剪力墙结构通过设置可更换连梁，在地震作用下集中损伤，保护主体结构不受或只受微小破坏，震后更换损伤构件即可恢复结构功能。参照现行规范和已有试验分析结果，在普通钢筋混凝土结构设计基础上，提出带有可更换连梁的钢筋混凝土结构实用设计方法，设定性能目标，总结设计流程。采用提出的设计方法对1个50层钢筋混凝土结构进行设计，并采用大型有限元分析软件ABAQUS建立数值模型，验证结构性能目标和提出的设计方法。结果表明:按该方法设计的带有可更换连梁的钢筋混凝土结构能满足所设定的性能目标，设计方法合理实用，为该新型结构的工程应用提供了参考。  相似文献   

Numerical analysis of the hydrofracturing behaviour of heterogeneous glutenite considering hydro‐mechanical coupling effects based on bonded particle models          下载免费PDF全文

Yang Ju  Yongliang Wang  Hongyu Dong  Yongming Yang 《国际地质力学数值与分析法杂志》2018,42(13):1493-1515

The heterogeneity of tight reservoirs significantly influences hydrofracturing behaviours, such as crack morphology, type, initiation, propagation, and distribution. The accurate characterisation of the influencing mechanisms has become a pivotal issue in enhancing the fracturing stimulation of tight reservoirs, as well as in the prediction of tight oil and gas production. In this study, the hydrofracturing behaviours of heterogeneous glutenites and their influencing mechanisms were numerically investigated based on bonded particle models (BPMs). The geometry and mechanical properties of the natural glutenites were obtained using microfocus computed tomography (CT) and triaxial tests and were used to construct heterogeneous BPMs. The hydrofracturing behaviours of the heterogeneous BPMs under various in‐situ stresses were analysed with hydro‐mechanical coupling effects considered and compared with those of homogeneous BPMs under the same conditions. The numerical results show that gravels in heterogeneous glutenites inhibit crack propagation. The shear cracks that appear in the initial stage of crack development subsequently propagate and distribute around the injection hole, and there are fewer hydraulic shear cracks than tensile cracks. The crack morphologies of BPMs are found to be consistent with the experimental forms. The numerical simulation provides a way to understand the mechanisms that govern the hydrofracturing crack types and propagation of heterogeneous reservoirs.  相似文献   

H型浮式垂直轴风力机刚—柔耦合多体动力学建模及仿真     

刘利琴  赵海祥  袁瑞  黄鑫  李焱 《海洋工程》2018,36(3):1-9

采用多体动力学方法研究了H型浮式垂直轴风力机的动力特性。将风力机叶片和塔柱处理为柔性体,浮式基础处理为刚性体,考虑柔性体的非线性变形,由拉格朗日第二类方程建立了浮式风力机系统的非线性刚—柔耦合多体动力学方程。系统载荷包括浮式基础受的波浪力、风机叶片旋转时受到的气动载荷、塔柱受到的风压载荷、系泊力以及系统阻尼力。编制了模拟系统响应的数值计算程序,该程序可以考虑浮式风力机系统的刚—柔耦合和气动力—水动力耦合效应。以5 MW风力机为例,计算了叶片的固有频率;分析转速对叶片固有频率的影响;计算风、浪联合作用下浮式风力机系统的动力响应。结果表明,随着风机转速的增加,叶片切向固有频率增加、法向固有频率减小;在风、浪联合作用下,浮式基础运动以波浪频率为主,气动载荷贡献较小。  相似文献   

手机视觉与惯性融合的松耦合滤波算法     

刘星  郭杭 《测绘通报》2020,(2):61-65

在智能手机和互联网的普及状态下，对高精度定位技术的需求也更加显著，精确定位服务已渗透到各个领域，如物联网、无人驾驶、机器快递员、应急救援等。在室外环境下，这些服务大多由全球卫星导航系统提供；然而，在深山丛林、矿井隧道、地下室等室内环境下，由于信号衰减及多径效应的影响，GPS无法正常工作。本文针对一些特殊的室内场景，研究了基于松耦合滤波的视觉惯性融合导航方法，设计了一个面向智能手机平台的室内行人定位系统。该方法视觉前端采用了快速、稳健的稀疏直接法，后端采用了扩展卡尔曼滤波器来融合惯性信息，能够有效融合视觉和惯性信息，达到恢复单目视觉尺度、提高稳健性的效果，实现了高精度的室内行人定位。  相似文献