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1.
江坪河水库坝址地段具有在高坝的地形、地貌与地质条件．但是，库首右岸发育出圩一曲溪河间地块，其上广布岩溶强烈发育的寒武系一奥陶系戳欧盐岩．岩溶渗漏问是该坝址方案能否成立的关键．本文研究了河间地块上岩溶及岩溶地下水系统发育规律，运用物探手段，综合地质及水文资料，探讨了河间地块上地下水位分布特点，认为该河间地块上存在地下水位高于正常富水位的地下分水岭，不存在岩溶渗漏问题． 相似文献
2.
江坪河水库坝址地段具有建高坝的地形、地貌与地质条件，但是，库首右岸发育梅坪－曲溪河间地块，其上广布岩溶强烈发育的寒武系－奥陶系碳酸盐岩，岩深渗漏问题是该坝址方案能否成立的关键，本文研究了河间地块上岩溶及岩溶地下水系统发育规律，运用物深手段，综合地质及水文资料，探讨了河间地块上地下水位分布特点，认为该河间地块上存在地下水位高于正常蓄水位的地下分水岭，不存在岩溶渗漏问题。 相似文献
3.
溶蚀作用下古岩溶盆地系统中介质场演化模拟 总被引：2，自引：1，他引：1
为了研究古岩溶盆地在溶蚀作用下碳酸盐岩油气储层介质场的演化规律,基于地下水渗流理论和碳酸盐溶蚀动力理论,用数值模型模拟了均质盆地和非均质盆地2种岩溶盆地含水系统发育过程。岩溶盆地含水系统演化过程中总伴随着裂隙差异溶蚀,不管均质盆地还是非均质盆地,都越来越非均质化,强溶蚀带集中在潜水位及优势裂隙附近,在侵蚀基准面和构造裂隙及层理等大裂隙处会形成高孔隙率、渗透率的良好储层。受介质场非均质化反作用,岩溶高地区潜水位随系统演化不断下降,潜水面处的强烈溶蚀随水位不断下切而使高地区改造成竖直裂隙发育的厚储层;坡地区水平径流活跃,易于形成水平裂隙发育的储层;平原区水位相对稳定,溶蚀作用主要发生大裂隙和侵蚀基准面处,但在大裂隙网内经溶蚀可形成局部高孔隙率储层。对比两子模型发现,在岩溶盆地含水系统中,主导渗流场都要经历由局部流场向二级流场、二级流场向全局流场的转变,前者发生在坡地区内部,后者发生在坡地区与平原区之间;流畅的渗流场转换更有利于介质场发育,受大裂隙网导水作用,非均质盆地比均质盆地更快捷、更顺利地实现主导流场升级,溶蚀作用更强烈,3 ka后非均质盆地比均质盆地的孔隙率增幅大34%。 相似文献
4.
基于GMS的岩溶山区三维地下水流模式识别 总被引：3，自引：1，他引：2
以高岚河东部多条支沟切割形成的连排型河间地块为研究区,基于1∶5万岩溶水文地质调查成果,利用GIS技术和径流分割,量化岩溶含水系统顶底板高程、获取入渗补给系数及地下水径流量等数据,运用三维地下水流数值模拟及粒子追踪地下水流线的方法,得出了研究区的地下水流模式。其结果表明:研究区地下水流模式主要受区域尺度的势源和势汇控制,局部的地形起伏对地下水位的影响不明显;支沟切割较深的凉伞沟、滩淤河流域,水流驱动力大,有利于局部水流系统的发育;随着东部补给高程的增加,流程逐渐增长,多发育局部水流系统,至山脊附近多发育排泄至高岚河的中间水流系统。当研究区年降雨量由中等的1 021.1 mm降为多年最低的725.5 mm时,由东部补给区排泄至高岚河的中间水流系统增加;在此降雨强度区间,不具备发育越过河间地块的中间或区域地下水流系统。 相似文献
5.
为揭示隐伏型岩溶含水系统在不同边界条件与介质特征下的发育状况,基于地下水渗流和碳酸盐岩溶蚀理论构建耦合裂隙网络渗流与碳酸盐岩溶蚀的岩溶裂隙网络溶蚀扩展模型,模拟再现了河间隐伏型岩溶含水系统平面上发育演化过程。结果显示:岩溶系统发育过程中流量变化呈现三个阶段:第Ⅰ阶段为缓慢层流阶段,流量增速为2.2×10 -6 mL·(s·a) -1,持续时间与初始水头差呈对数关系;第Ⅱ阶段为极快速紊流阶段,流量增速为5.5×10 2 mL·(s·a) -1,持续时间与初始水头差呈线性关系;第Ⅲ阶段为快速紊流阶段,流量增速为26 mL·(s·a) -1。优势裂隙的存在使得岩溶裂隙网络溶蚀演化加快,非均质系统进入极快速紊流阶段所用时间较均质系统缩短了53%,裂隙溶蚀扩展的速度加快了12.5%。 相似文献
6.
裂隙岩溶含水系统溢流泉演化过程的数值模拟 总被引：5，自引：5，他引：0
本文利用非连续裂隙网络介质模型,耦合水动力条件和碳酸盐溶蚀动力条件,建立岩溶含水系统演化的数学模型,并用数值法进行模拟分析。在已建数值模型基础上,构造了两组实例模型(降水入渗补给的裂隙岩溶含水系统和河流补给的裂隙岩溶含水系统)来研究裂隙岩溶系统中溢流泉早期演化过程。模拟发现,裂隙岩溶含水系统演化过程中,裂隙不断被溶蚀拓宽,致使系统中潜水位不断下降,许多小泉被疏干;同时不同裂隙之间存在溶蚀差异,在潜水位及优势通道附近的裂隙溶蚀速度快,而其它位置则相对慢得多,差异溶蚀促使系统形成优势溶管,优势溶管逐渐袭夺水流,形成大泉。另外对比两模型发现,降水入渗为主要补给源的裂隙岩溶含水系统,泉管道从汇向源发育;而河流入渗为主要补给源的裂隙岩溶含水系统,泉管道则由源向汇发育。 相似文献
7.
8.
基于岩溶演化模型的隧道突水危险性评价 总被引：1，自引：0，他引：1
《地质科技情报》2015,(5)
岩溶隧道是否发生涌突水,主要取决于洞身岩溶发育程度和岩溶系统结构类型,而这与岩溶系统的演化过程密切相关。岩溶系统的发育演化始于具有侵蚀性的水对可溶性岩体中裂隙的溶蚀扩展。基于此,本研究耦合了渗流模型和溶蚀扩展模型,并结合鸡公岭隧道区水文地质背景资料,建立了隧道区岩溶系统岩溶演化模拟模型,模拟再现了隧道区岩溶含水介质的发育情况。结果显示:随着岩溶系统的发育演化,整个系统中裂隙不断被溶蚀扩展,差异性溶蚀越来越显著,岩溶含水介质的非均质性越来越强;同时随着埋深的增加,岩溶发育程度及非均质性越来越弱;浅部和深部裂隙的平均溶蚀扩展率相差近1 500倍;鸡公岭隧道洞身标高处岩溶发育微弱,裂隙溶蚀扩展较小,仍为裂隙岩体,其等效渗透系数为0.51m/d,岩溶突水概率极低,隧道发生涌水时的涌水量为127.9m3/d,对隧道施工影响较小。 相似文献
9.
降雨对裂隙型岩溶含水系统演化影响的数值模拟研究 总被引：5，自引：5，他引：0
本文在构建有降雨入渗及河流补给的裂隙型岩溶含水系统的概念模型基础上,采用有限差分数值方法,利用裂隙渗流立方定律及Dreybort（1996）经过实验总结出的碳酸钙溶蚀经验公式,定量地计算了裂隙型岩溶含水系统经过10 000年溶蚀的演化形态及岩溶泉的变化。模拟发现,岩溶含水系统的溶蚀主要发生在降雨入渗面处、河流补给处和岩溶泉的出露点附近。随着溶蚀的进行,岩溶含水系统的潜水位不断下降部分岩溶泉被疏干,通过计算岩溶泉汇流管道的隙宽变化,发现岩溶含水系统会出现明显的差异性溶蚀。在模拟过程中调节降雨量的大小发现降雨入渗对有河流补给的岩溶含水系统的演化影响并不显著。 相似文献
10.
碳酸盐岩往往含有较多泥质夹层,多发育浅部岩溶裂隙,影响工程基础稳定性。文章依托广西合山市溯河矿区某道路浅部岩溶调查成果,分析了薄层灰岩岩溶宏观形态和垂直分布特征,按照溶蚀程度将其分为碎屑残留带、表层岩溶带和下部包气带;通过室内溶蚀试验,分析了矿物组成、CO2及水动力条件影响下的溶蚀规律;对比分析了薄层和厚层岩溶发育特征。结果表明:（1）薄层灰岩浅部岩溶发育程度与微地貌有关,通常在山谷和地下水强径流带溶蚀作用更为强烈;（2）薄层灰岩溶蚀优先开始于方解石,在岩石表面形成溶孔、粗糙程度增加,提供了侵蚀性溶液流动通道;（3）薄层灰岩岩溶较厚层灰岩岩溶规模小,分布较为均匀,由地表土体渗入地下岩体的地下水含有较多侵蚀性CO2水溶液,会促进岩溶作用的进行;（4）薄层灰岩浅部岩溶发育分布模型为:发育均匀的微小溶蚀裂隙在溶蚀下渗过程中遇到软弱夹层时会沿水平向扩展并随进一步溶蚀作用被充填,垂向深部发展时溶蚀作用逐步消散。 相似文献
11.
A supernova explosion in a close binary system in which one of the components is a compact magnetized object (neutron star or white dwarf) can form a narrow “tail” with length l t ～109 cm, width h t ～108 cm, and magnetic field B t ～106, due to the resulting shock wave flowing around the magnetosphere of the compact object. The energy released by the reconnection of magnetic field lines in this tail can accelerate electrons to relativistic speeds (γ≈104), creating the conditions required for powerful synchrotron radiation at energies from hundreds of keV to several MeV, i.e., for a gamma-ray burst (GRB). The duration of this radiation will depend on the power of the shock that forms during the supernova. If the shock is not sufficiently powerful to tear off the magnetosphere tail from the compact object, the duration of the GRB will not exceed l t /V A ≤1 s, and the conditions necessary for an “afterglow” at softer energies will not arise. If the shock is more powerful, the tail can be torn from the magnetosphere, forming a narrow ejection, which is perceived in its relativistic motion toward the observer(Γ～104) as an afterglow whose duration grows from tens of seconds at gamma-ray energies to tens of days in the optical. This may explain why afterglows are observed only in association with long GRBs (T 90>10 s). Very short GRBs (T 90<0.1 s) may be local, i.e., low-power, phenomena occurring in close pairs containing compact, magnetized objects, in which there is again an interaction between the magnetosphere of the compact object and a shock wave, but the shock is initiated by a flare on the companion, which is a red-dwarf cataclysmic variable, rather than by a supernova. 相似文献
12.
This paper presents a theoretical approach to analyse coupled, linear thermoporoelastic fields in a saturated porous medium under radial and spherical symmetry. The governing equations account for compressibility and thermal expansion of constituents, heat sink due to thermal dilatation of water and thermal expansion of the medium, and thermodynamically coupled heat–water flow. It has been reported in the literature that thermodynamically coupled heat–water flows known as thermo-osmosis and thermal filtration have the potential to significantly alter the flow fields in clay-rich barriers in the near field of a underground waste containment scheme. This study presents a mathematical model and examines the effects of thermo-osmosis and thermal-filtration on coupled consolidation fields in a porous medium with a cavity. Analytical solutions of the governing equations are presented in the Laplace transform space. A numerical inversion scheme is used to obtain the time-domain solutions for a cylindrical cavity in a homogeneous or a non-homogeneous medium. A closed form time-domain solution is presented for a spherical cavity in a homogeneous medium. Selected numerical solutions for homogeneous and non-homogeneous media show a significant increase in pore pressure and displacements due to the presence of thermodynamically coupled flows and a negligible influence on temperature. © 1998 John Wiley & Sons, Ltd. 相似文献
13.
A. N. Galybin 《国际地质力学数值与分析法杂志》1998,22(3):175-196
The problem of the equilibrium of a plane with a circular hole and a shear crack is considered to model failure of an excavation (borehole or circular opening) in rocks weakened by discontinuities (planes of weakness). It is assumed that sliding occurs in a part of the plane of weakness when the Mohr–Coulomb friction criterion is satisfied due to the stress redistribution caused by the excavation. The method of singular integral equations is employed to solve the boundary value problem. Geomechanical problems concerning borehole breakout and rockburst caused by fault-opening interaction are discussed. © 1998 John Wiley & Sons, Ltd. 相似文献
14.
The possible application of a Rindler type reference frame for studies of physical processes near the horizons of black and white holes is considered. New similar reference frames inside black and white holes in the region T of a Kruskal wormhole are introduced. 相似文献
15.
The focus of this contribution is to develop a complex variable function method to solve the two-dimensional scattering of plane waves by a lined cylindrical cavity in the poroelastic half-plane. The poroelastic half-plane is based on Biot’s dynamic theory, and the governing equations are solved by reduction to three Helmholtz equations. The lining structure can be treated as an elastic material and decoupled into two Helmholtz equations. Here, the large circle assumption is applied to simulate the half-plane boundary. By using appropriate boundary conditions and continuity conditions, the unknown coefficients in the potentials can be determined. Selected numerical results are presented in this paper. 相似文献
16.
On a controversial method for modeling a coregionalization 总被引：2，自引：0，他引：2
P. Goovaerts 《Mathematical Geology》1994,26(2):197-204
This paper reviews two alternative approaches for modeling the (cross) variograms in a coregionalization: (1) fitting the traditional linear model of coregionalization. or (2) deducing the crossvariogram model as a linear combination of prior direct (auto) variogram models while checking the Cauchy-Schwarz inequalities. We show that the second approach has no practical advantage over the traditional one and may not be valid if more than two variables are involved. In such case. Cauchy-Schwarz inequalities are necessary but not sufficient conditions for validity of a coregionalization model. 相似文献
17.
A mudcake formed on the borehole wall between a fluid-filled porous formation and the borehole fluid can affect Stoneley wave propagation used to estimate the formation permeability. The mudcake effect on the permeability dependence of radial oscillations of borehole fluid is investigated in a system with a source generating radial acoustic waves in the borehole and hydrophones (pressure sensors) that record the respective attenuating oscillations of the borehole fluid. The permeability of the porous formation is estimated from theoretical permeability dependence of the attenuation exponent, knowing the time dependence of the exponential attenuation of borehole fluid oscillations. 相似文献
18.
The Behaviour of a Reinforced Soil Mattress Spanning a Cavity Modelled in a Geotechnical Centrifuge 总被引：1，自引：0，他引：1
Sinkholes can occur on land underlain by dolomite and cause substantial damage to buildings and even loss of life. More than four million people work or reside on dolomite land in South Africa and it is therefore important to be able to construct safely on dolomite land and to minimise the risk of damage to infrastructure and loss of life. Compacted soil mattresses are often used to found structures on areas underlain by dolomite. This study investigated the effect of tensile reinforcement on the behaviour of a soil mattress spanning an underlying water filled cavity designed to impose a cover subsidence sinkhole. Three small-scale models, each consisting of a soil mattress with a cover subsidence sinkhole forming underneath, were constructed and tested in a geotechnical centrifuge. In the first test, an unreinforced soil mattress was tested and in two more tests, reinforced soil mattresses with different reinforcement strengths were tested. The settlement of the unreinforced soil mattress was initially less than that of the reinforced soil mattresses up to the point at which it failed suddenly. Neither of the reinforced soil mattresses failed suddenly, but both experienced large surface settlements that would have led to substantial damage to an overhead structure. 相似文献
19.
The impact force to a rigid obstruction from a granular mass sliding down a smooth incline provides insights into the solid-like and fluid-like behaviors of granular avalanches and useful information for risk assessment and engineering design against landslides. In this study, a series of 2-D flume tests were performed to systematically investigate the effects of inclination angle, sliding distance, and initial relative density on the flow front velocity and impact force on a rigid obstruction. The experimental results show that for inclination angles smaller than the critical state friction angle of sand, an increase in the sliding distance and/or initial relative density results in smaller impact forces; for higher inclination angles, the trend is reversed. Based on the experimental results, an analytical equation is proposed to estimate the flow front velocity and an empirical approach is presented to estimate the maximum impact force based on elastic solid and hydrodynamic methods. The proposed equations are found to provide more accurate predictions for the maximum impact force than similar equations in the literature. 相似文献
20.
滨海地区社会与经济的发展引发了各种各样的水文地质问题, 因此对滨海地区的水文地质条件, 尤其是地下水与海水之间的水力联系的研究尤为重要.本文考察了海底露头处具有淤泥层的滨海含水层系统中由海潮引起的水头波动.该系统由潜水含水层、承压含水层和介于其间的弱透水层构成.建立了该系统的数学模型, 得到了该模型的解析解.该解析解包含2个无量纲参数: 弱透水层的相对越流系数和淤泥层的相对透水系数.解析解表明, 淤泥层使各处的水头波幅被缩小了一个常数倍(波幅缩减因子), 并使各处的波动相位产生了一个不超过45°的正位移常数(时滞).该时滞对半日潮不超过1.5h, 对全日潮不超过3h.波幅缩减因子和正位移常数只与弱透水层的相对越流系数和淤泥层的相对透水系数有关.当这两个无量纲参数取某些特殊值时, 本次研究的解和前人考虑的几种较简单情形所对应的解一致.承压含水层中水头波幅随着淤泥层的相对透水系数的递增而严格递增, 随弱透水层的相对越流系数的递增而严格递减; 波动相位随着这2个无量纲参数的递增均严格递减.分析表明弱透水层的越流和淤泥层的存在均对承压含水层水头波动有显著影响. 相似文献