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51.
Numerical simulation of groundwater flowing to horizontal seepage wells under a river 总被引:6,自引:0,他引:6
A horizontal seepage well, consisting of an interconnected vertical well, galleries, chambers and small-diameter radiating
bores, is used to acquire relatively clean water that has been filtered through natural alluvial deposits in a riverbed. It
has wide application, especially in arid and semi-arid areas. The lack of calculation formulae or models for horizontal seepage
wells, up until now, has resulted in several false applications. Based on the analysis of groundwater flow characteristics,
it has been concluded that several flow regimes coexist and hydraulic head loss exists in the horizontal seepage well. To
avoid the difficulty of confirming the flux or head distribution in such a complex system, the model boundary of the whole
horizontal seepage well has been moved to that of just the vertical well, and the well-aquifer system was treated as a heterogeneous
medium, where the horizontal seepage well itself is a highly permeability medium. A mathematical model has been developed,
based on the coupled seepage-pipe flow, by the introduction of equivalent hydraulic conductivity according to different flow
regimes. Then a three-dimensional finite difference numerical model, based on the mathematical model, was developed and applied
to a horizontal seepage well in China. The numerical model verified the groundwater flow characteristics of the horizontal
seepage well.
An erratum to this article can be found at 相似文献
52.
In the work reported here the comprehensive physics‐based Integrated Hydrology Model (InHM) was employed to conduct both three‐ and two‐dimensional (3D and 2D) hydrologic‐response simulations for the small upland catchment known as C3 (located within the H. J. Andrews Experimental Forest in Oregon). Results from the 3D simulations for the steep unchannelled C3 (i) identify subsurface stormflow as the dominant hydrologic‐response mechanism and (ii) show the effect of the down‐gradient forest road on both the surface and subsurface flow systems. Comparison of the 3D results with the 2D results clearly illustrates the importance of convergent subsurface flow (e.g. greater pore‐water pressures in the hollow of the catchment for the 3D scenario). A simple infinite‐slope model, driven by subsurface pore‐water pressures generated from the 3D and 2D hydrologic‐response simulations, was employed to estimate slope stability along the long‐profile of the C3 hollow axis. As expected, the likelihood of slope failure is underestimated for the lower pore pressures from the 2D hydrologic‐response simulation compared, in a relative sense, to the higher pore pressures from the 3D hydrologic response simulation. The effort reported herein provides a firm quantitative foundation for generalizing the effects that forest roads can have on near‐surface hydrologic response and slope stability at the catchment scale. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
53.
54.
隧道开挖过程中的渗透变形问题分析——结合南京地区工程实例 总被引:1,自引:0,他引:1
本文从水文地质条件、土体结构和力学性质等方面分析了南京地区土层中隧道开挖所引起的渗透变形问题。经研究认为可通过控制所构筑地下防渗墙深度、厚度及质量来防止渗透变形。实践证明该方法是有效的。 相似文献
55.
56.
Based on grey set, grey numbers and their operation properties, the grey numerical model of groundwater seepage system was
set up for the first time, the whole grey solving method of the model was given and it was proved that the common solving
method of the model was only a special case of the grey solving methods. At the same time, the grey solving method was compared
widely with common solving method, classical numerical method. The study shows that the grey solving method is better in depicting
the procedure of transporting grey data of groundwater system. On the basis of the theoretical study, two basic kinds of cases
about groundwater seepage were selected: the prediction of pit yield and the evaluation of groundwater resources on a groundwater
basin. In the cases, systematical analyses were made for generalization and greylization of the hydrogeologic conditions,
setting up of the grey model, identification and correction of the model as well as its prediction and evaluation. It was
pointed out that when the grey numerical model is used to predict pit yield, the upper limit of the “grey band” of groundwater
level cannot be higher than planed safe groundwater level, when evaluating the groundwater resource, the lower limit of the
“grey band” of groundwater level cannot be lower than controlled level of groundwater. 相似文献
57.
58.
Summary
Hydrofracture Mechanisms in Rock During Pressure Grouting. The paper examines the basic meachnisms controlling the initiation of fractures in rocks and layered soils during pressure grouting, and their subsequent propagation into the ground mass. Previous analyses of fracture initiation have tended to concentrate on simplified models in which the ground is treated as an impervious elastic or Mohr-Coulomb continuum. The present method allows for the porous or fissured nature of the ground by considering the effect of seepage forces induced by the pore pressure gradient. The effect is quantified by use of a parameterN such that the ratio of fluid force used in expanding the injection hole, to that used in forcing fluid through void spaces, isN to (1—N).Analysis of hydrofracture propagation is based on stress analysis of a borehole in an elastic continuum, the propagating fracture zone around the borehole being represented as a non-elastic material governed by the Mohr-Coulomb failure criterion. This is supplemented by an energy approach which equates the energy supplied to the ground from the injection pump, with the energy stored in the ground and the energy necessary to fracture it.
Nomenclature A area of new cracks created per unit volume of time t - E total work done by injection fluid - E i irrecoverable component of energy - E i c work done in fracturing rock or soil - E i l work done to overcome various frictional forces in grouting system - E i p work done to cause plastic deformation of fractured zone - E i s work done to overcome shear strength of fluid during flow - E i v work done to overcome frictional drag between fluid and rock in soil surfaces during flow - E r recoverable component of energy - E r f elastic strain energy stored in fluid - E r s elastic strain energy stored in rock or soil - h height of overburden - i j 1, 2, 3 - K 0 coefficient of horizontal earth pressure - k permeability of ground to grout - L length of cylindrical grout source - n rock or soil porosity - p average fluid pressure between timet and (t + t) - p 0 injection pressure - R radius of grout front - r radial distance from borehole axis - r 0 radius of borehole - r 1 radius of fractured zone - S specific surface area of rock or soil - S T tensile strength of rock or soil - t time - u grout seepage velocity - V volume of grout injected - v volumetric strain - specific surface energy of rock - bulk density of rock or soil - i j e elastic strain increment tensor - i j plastic strain increment tensor - v Poisson's ratio - i j average stress tensor in the ground during timet and (t + t) - R , T, Z radial, tangential and vertical stresses induced by grouting - r , t , z radial, tangential and vertical stress around borehole before grouting - grout shear strength - angle of internal friction of rock or soil With 7 Figures 相似文献
Zusammenfassung Brucherscheinungen im Fels bei Verprearbeiten. In der Arbeit wird der grundlegende Mechanismus untersucht, welcher bei Verpreßarbeiten in Fels und geschichtetem Boden zur Einleitung und Ausbreitung von Brüchen führt. Frühere Untersuchungen des Bruchbeginns stützten sich im wesentlichen auf vereinfachte Modelle, in denen der Untergrund als undurchlässiges Kontinuum angesehen wird, das entweder elastisch ist oder der Mohr-Coulombschen Bruchbedingung genügt. Die neue Methode berücksichtigt dagegen eine Porosität oder Klüftung des Untergrundes durch Ansatz der vom strömenden Medium auf das Gebirge ausgeübten Belastung. Diese Belastung wird aufgeteilt in einen Druckverlust an der Bohrlochwand (gleich ParameterN mal Verpreßdruck) und die entsprechende, über den gesamten durchströmten Bereich verteilte Belastung.Die Untersuchung der Bruchausbreitung geht von der Spannungsermittlung um ein Bohrloch in einem elastischen Kontinuum aus, wobei in der sich ausbreitenden Bruchzone um das Bohrloch herum nichtelastisches Material angenommen wird, das dem Mohr-Coulombschen Bruchkriterium genügt. Zur Ergänzung dient eine Energie-Betrachtung, bei der die von der Injektionspumpe abgegebene Energie gleichgesetzt wird der im Untergrund gespeicherten Energie und der aufgewendeten Brucharbeit.
Résumé Les mécanismes de la fracturation hydraulique dans les roches pendant les injections sous pression. Le mémoire examine les mécanismes fondamentaux qui gouvernent l'initiation des ruptures dans les roches et les sols stratifiés, au cours des injections et leur propagation dans les massifs. Les analyses antérieures de l'initiation de la rupture, se sont concentrées sur des modèles simplifiés où l'on considérait la roche comme un milieu élastique et imperméable, ou comme un milieu de Mohr-Coulomb. La présente méthode admet que le massif est poreux ou fissuré, en considérant l'action des forces de percolation engendrées par le gradient de pression interstitielle. Cette action est quantifiée par un paramètreN, tel que le rapport de la force du liquide employée à dilater le forage d'injection, à celle employée pour forcer le coulis à travers les vides soitN/(1—N). L'analyse de la propagation des ruptures se base sur l'analyse des contraintes autour d'un forage dans un milieu élastique, alors que la zone de la rupture qui se propage autour du forage est représentée par un milieu non-élastique admettant le critère de rupture de Mohr-Coulomb. Cette analyse est complétée par une approche énergétique, où l'énergie qui est fournie au massif par la pompe d'injection est égalée à l'énergie emmagasinée dans la roche et à l'énergie de rupture.
Nomenclature A area of new cracks created per unit volume of time t - E total work done by injection fluid - E i irrecoverable component of energy - E i c work done in fracturing rock or soil - E i l work done to overcome various frictional forces in grouting system - E i p work done to cause plastic deformation of fractured zone - E i s work done to overcome shear strength of fluid during flow - E i v work done to overcome frictional drag between fluid and rock in soil surfaces during flow - E r recoverable component of energy - E r f elastic strain energy stored in fluid - E r s elastic strain energy stored in rock or soil - h height of overburden - i j 1, 2, 3 - K 0 coefficient of horizontal earth pressure - k permeability of ground to grout - L length of cylindrical grout source - n rock or soil porosity - p average fluid pressure between timet and (t + t) - p 0 injection pressure - R radius of grout front - r radial distance from borehole axis - r 0 radius of borehole - r 1 radius of fractured zone - S specific surface area of rock or soil - S T tensile strength of rock or soil - t time - u grout seepage velocity - V volume of grout injected - v volumetric strain - specific surface energy of rock - bulk density of rock or soil - i j e elastic strain increment tensor - i j plastic strain increment tensor - v Poisson's ratio - i j average stress tensor in the ground during timet and (t + t) - R , T, Z radial, tangential and vertical stresses induced by grouting - r , t , z radial, tangential and vertical stress around borehole before grouting - grout shear strength - angle of internal friction of rock or soil With 7 Figures 相似文献
59.
岩溶坝区透水参数的随机模型 总被引:1,自引:0,他引:1
岩溶坝区的渗透特性受高应力场的作用,使其固有的非均质各向异性更趋复杂,采用确定性的方法不能准确的描述其本质特性。本文在对岩溶坝区透水性随机场进行分析的基础上,提出了渗透随机性的数学描述。考察岩溶坝区主要的两场作用,即渗流与应力场的耦合。基于Taylor随机有限元建立了渗流应力耦合的随机微分方程格式,并对耦合随机模型反演求解渗透参数提出了思路。 相似文献
60.