袋装石土工袋剪切力学特性试验研究     

樊科伟  刘斯宏  廖洁  方斌昕  王建磊 《岩土力学》2020,41(2):477-484

袋装石土工袋堆叠过程中在土工袋接触面形成的咬合和嵌固作用，对土工袋剪切力学强度和破坏形式有较大的影响。通过一系列直剪试验研究了咬合和嵌固作用的影响，试验结果表明：袋装石土工袋层间咬合和嵌固作用能够增大土工袋抗剪强度；咬合作用随着土工袋上部竖向应力的增大有所减小，而嵌固作用则有所增大；袋装石土工袋在剪切过程中会产生两种破坏形式，分别为土工袋袋体自身变形和层间滑动破坏；土工袋组合体在受到水平剪切力时会发生整体变形，随后在组合体内部产生阶梯型滑动面，滑裂面的形状随着竖向荷载的增大而有所不同，相应的抗剪强度也会随着滑动面的改变而变化。  相似文献   

Coupled groundwater flow and heat transport simulation for estimating transient aquifer–stream exchange at the lowland River Spree (Germany)          下载免费PDF全文

Gunnar Nützmann  Christian Levers  Jörg Lewandowski 《水文研究》2014,28(13):4078-4090

Subsurface flow and heat transport near Freienbrink, NE Germany, was simulated in order to study groundwater–surface water exchange between a floodplains aquifer and a section of the lowland River Spree and an adjacent oxbow. Groundwater exfiltration was the dominant process, and only fast surface water level rises resulted in temporary infiltration into the aquifer. The main groundwater flow paths are identified based on a 3D groundwater flow model. To estimate mass fluxes across the aquifer–surface water interfaces, a 2D flow and heat transport modelling approach along a transect of 12 piezometers was performed. Results of steady‐state and transient water level simulations show an overall high accuracy with a Spearman coefficient ρ = 0.9996 and root mean square error (RMSE) = 0.008 m. Based on small groundwater flow velocities of about 10^?7 to 10^?6 ms^?1, mean groundwater exfiltration rates of 233 l m^?2 d^?1 are calculated. Short periods of surface water infiltration into the aquifer do not exceed 10 days, and the infiltration rates are in the same range. The heat transport was modelled with slightly less accuracy (ρ = 0.8359 and RMSE = 0.34 °C). In contrast to the predominant groundwater exfiltration, surface water temperatures determine the calculated temperatures in the upper aquifer below both surface water bodies down to 10 m during the whole simulation period. These findings emphasize prevailing of heat conduction over advection in the upper aquifer zones, which seems to be typical for lowland streams with sandy aquifer materials and low hydraulic gradients. Moreover, this study shows the potential of coupled numerical flow and heat transport modelling to understand groundwater–surface water exchange processes in detail. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Numerical modeling of three‐phase dissolution of underground cavities using a diffuse interface model     

H. Luo  F. Laouafa  J. Guo  M. Quintard 《国际地质力学数值与分析法杂志》2014,38(15):1600-1616

Natural evaporite dissolution in the subsurface can lead to cavities having critical dimensions in the sense of mechanical stability. Geomechanical effects may be significant for people and infrastructures because the underground dissolution may lead to subsidence or collapse (sinkholes). The knowledge of the cavity evolution in space and time is thus crucial in many cases. In this paper, we describe the use of a local nonequilibrium diffuse interface model for solving dissolution problems involving multimoving interfaces within three phases, that is, solid–liquid–gas as found in superficial aquifers and karsts. This paper generalizes developments achieved in the fluid–solid case, that is, the saturated case [1]. On one hand, a local nonequilibrium dissolution porous medium theory allows to describe the solid–liquid interface as a diffuse layer characterized by the evolution of a phase indicator (e.g., porosity). On the other hand, the liquid–gas interface evolution is computed using a classical porous medium two‐phase flow model involving a phase saturation, that is, generalized Darcy's laws. Such a diffuse interface model formulation is suitable for the implementation of a finite element or finite volume numerical model on a fixed grid without an explicit treatment of the interface movement. A numerical model has been implemented using a finite volume formulation with adaptive meshing (e.g., adaptive mesh refinement), which improves significantly the computational efficiency and accuracy because fine gridding may be attached to the dissolution front. Finally, some examples of three‐phase dissolution problems including density effects are also provided to illustrate the interest of the proposed theoretical and numerical framework. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Scientists’ framing of the ocean science–policy interface     

《Global Environmental Change》2015

Scientists’ ideas, beliefs, and discourses form the frames that shape their choices about which research to pursue, their approaches to collaboration and communicating results, and how they evaluate research outputs and outcomes. To achieve ocean sustainability, there are increasing calls for new levels of engagement and collaboration between scientists and policy-makers; scientists’ willingness to engage depends on their current and evolving frames. Here, I present results about how scientists involved in diverse fields of ocean research perceived their role as scientists working at or near the ocean science–policy interface and how this related to their perceptions regarding ocean research priorities. The survey of 2187 physical, ecological and social scientists from 94 countries showed that scientists held different perspectives about their appropriate level of engagement at the ocean science–policy interface and the relative primacy of science versus politics in formulating ocean policy. Six clusters of scientists varied in their frames; three clusters accounted for 94% of the sample. Of 67 research questions identified from 22 research prioritization and horizon scanning exercises, the top eight were shared among all three clusters, showing consistency in research priorities across scientists with different framings of their role at the science–policy interface. Five focused on the mechanisms and effects of global change on oceans, two focused on data collection and management for long-term ocean monitoring, and one focused on the links between biodiversity and ecological function at different scales. The results from this survey demonstrated that scientists’ framings of the role of ocean science at the science–policy interface can be quantified in surveys, that framing varies among scientists, and that research priorities vary according to the framings.  相似文献   

Co-productive governance: A relational framework for adaptive governance     

《Global Environmental Change》2015

Adaptive governance focuses our attention on the relationships between science and management, whereby the so-called ‘gaps’ between these groups are seen to hinder effective adaptive responses to biophysical change. Yet the relationships between science and governance, knowledge and action, remain under theorized in discussions of adaptive governance, which largely focuses on abstract design principles or preferred institutional arrangements. In contrast, the metaphor of co-production highlights the social and political processes through which science, policy, and practice co-evolve. Co-production is invoked as a normative goal (Mitchell et al., 2004) and analytical lens (Jasanoff, 2004a, Jasanoff, 2004b), both of which provide useful insight into the processes underpinning adaptive governance. This paper builds on and integrates these disparate views to reconceptualize adaptive governance as a process of co-production. I outline an alternative conceptual framing, ‘co-productive governance’, that articulates the context, knowledge, process, and vision of governance. I explore these ideas through two cases of connectivity conservation, which draws on conservation science to promote collaborative cross-scale governance. This analysis highlights the ways in which the different contexts of these cases produced very different framings and responses to the same propositions of science and governance. Drawing on theoretical and empirical material, co-productive governance moves beyond long standing debates that institutions can be rationally crafted or must emerge from context resituate adaptive governance in a more critical and contextualized space. This reframing focuses on the process of governance through an explicit consideration of how normative considerations shape the interactions between knowledge and power, science and governance.  相似文献   

基于两种颗粒体模型的巷道围岩应力应变分析     

伍小林  王学滨  潘一山 《中国地质灾害与防治学报》2011,22(4):56-62

本文将岩石视为颗粒体材料,采用两种模型对巷道围岩的应力、应变及破坏区的分布规律进行了数值模拟。第一种模型是连续介质模型,其中考虑了颗粒、界面及基体。第二种模型是将第一种模型中的基体去掉。研究结果表明:当基体强度参数降低较少时,巷道围岩中的环向和径向应力在传统结果附近波动;当基体强度参数降低较多时,两种应力的波动幅度提高,而且,基体位置的应力向其周围的颗粒或界面转移。第二种模型结果的波动幅度更大。随着基体强度参数的降低,巷道围岩中的应变集中区向深部转移,形成相互交织的滑移线网,滑移线网的位置主要位于基体和界面中,这与第二种模型的结果有明显的差异(多个环向的应变集中区)。  相似文献   

核磁共振地下水探测技术在水源勘察及确定地下咸淡水界面中的应用与研究     

赵义平  汪馨竹  王文婷 《华北地质》2011,34(1):76-80

地面核磁共振找水技术是目前世界上唯一的直接找水方法.笔者通过该技术在内蒙古五原县乡镇安全饮水工程水源勘察中的应用,对如何确定地下咸淡水界面开展了研究工作.通过所获得的解译成果与钻孔资料的对比,认为在依据区域水文地质资料的基础上,用该技术确定地下咸淡水界面位置较为准确;在无区域水文地质资料的情况下,单以核磁共振解译成果能...  相似文献   

重力界面反演改进算法的比较与应用     

张冲  吴国超  宋立成  袁志明  乔中坤 《世界地质》2015,34(3):819-824

为得到更接近地下真实分布的反演界面,笔者比较分析Parker-Oldenburg反演和改进迭代反演,发现改进迭代反演方法不仅可以避免计算放大项,而且能够得到更好结果。通过理论模型,对经典Parker-Oldenburg方法和改进迭代反演方法的计算速度、迭代收敛性和结果精确性进行比较,结果表明改进迭代反演方法在保证计算速度和迭代收敛的情况下,能获得更精确的地下界面结构。通过实际数据验证了改进迭代反演的有效性和实用性。  相似文献   

构造-岩性油藏油水微观分布规律与主控因素探讨     

张创 《地质与勘探》2011,47(3):518-523

在对油水接触面形态和油水过渡带厚度的分布规律进行定量分析的基础上,以苏北盆地花17断块为例,结合油井生产动态特征分析了构造-岩性油藏中油水分布规律,并探讨了其影响因素.结果表明,在实际油藏中油水接触面是一个呈波状起伏的面,其在自由水面以上的高度随残余油饱和度下的毛管压力增大而抬高;油水过渡带厚度仅与束缚水饱和度和残余油...  相似文献   

基于振动台的动力子结构试验界面反力获取方法   总被引：2，自引：0，他引：2  

李振宝  李晓亮  唐贞云  蒋华戈 《地震工程与工程振动》2011,31(3):65-70

基于振动台的实时子结构动力试验是一种新型的结构动力试验方法.该试验方法引入了“子结构”这一概念,不仅减小了常规振动台试验对于试验规模的限制,而且克服了拟动力子结构试验中无法考虑加载速率影响的问题.由于该试验方法将整体结构拆分为数值子结构和物理子结构两部分,二者之间通过交界面相互作用力实现实时数据交互,以保证子结构体系与...  相似文献