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51.
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
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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
54.
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
55.
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57.
应用遥感技术预测油气勘探靶区具有低成本、高效率的特点。目前有直接和间接两种油气遥感方法用于预测油气勘探靶区。本文简单介绍了这两种方法的原理,重点对遥感影像中的线-环影像构造异常和烃渗漏异常所表现的特征进行了全面的总结,最后对遥感技术在预测油气勘探靶区的应用前景进行了展望。 相似文献
58.
Engineering geological properties of the ground at the Chapar-Abad Dam were investigated in order to evaluate seepage problems and to select a proper method of water-proofing prior to construction. The dam is located to the northwest of Iran and is undergoing construction phase. The geology of the site consists of a series of Early Cambrian limestones and shales that crop out on the abutments and a valley that is filled by 60 m of alluvium deposits. The presence of thick alluvium deposits with various coefficients of permeability along the foundation demonstrates a possible seepage problem after water impoundment in the reservoir. The potential of water seepage was evaluated by the study of joint systems of the rock units, the use of numerical analysis to simulate water flow in the ground, and by conducting in-situ tests to estimate the permeability's values. Based on the obtained results and by reviewing many types of water-proofing methods regarding cost, feasibility and safety factors, the installation of a grout curtain is suggested. 相似文献
59.
In wet soils, zones of saturation naturally develop in the vicinity of impermeable strata, surface ponds and subterranean cavities. Hydrology must be then concerned with transient flow through coexisting unsaturated and saturated zones. The models of advancing saturated zones necessarily involve a nonlinear free boundary problem.A closed-form analytic solution is presented for a nonlinear diffusion model under conditions of ponding at the surface. The soil water diffusivity is restricted to the special functional form D(θ) = a/(b − θ)2, where θ is the water content field to be determined and a, b are positive constants. The explicit solution depends on a parameter C (determined by the data of the problem), according to two cases: 1 < C < C1 or C ≥ C1, where C1 is a constant which is obtained as the unique solution of an equation. This result complements the study given in P. Broadbridge, Water Resources Research, 1990, 26, 2435–2443, in order to established when the explicit solution is available. The behavior of the bifurcation parameter C1 as a function of the driving potential is studied with the corresponding limits for small and large values. Moreover, the sorptivity is proven to be continuously differentiable function of the variable C. 相似文献
60.
1981年以来对察尔汗盐湖三次渗漏试验结果表明,盐田渗漏是盐田土层与外界条件综合作用的结果,在盐田建设和生产管理过程中,应结合不同地点的土层特性、工程地质条件和其它有关条件,采取不同的处理措施。 相似文献