Uncertainty Analysis of Radionuclide Transport in a Fractured Coastal Aquifer with Geothermal Effects

Groundwater flow and radionuclide transport at the Milrow underground nuclear test site on Amchitka Island are modeled using two-dimensional numerical simulations. A multi-parameter uncertainty analysis is adapted and used to address the effects of uncertainties associated with the definition of the modeled processes and the values of the parameters governing these processes. In particular, we focus on the effects on radioactive transport of uncertainties associated with conduction and convection of heat relative to the uncertainties associated with other flow and transport parameters. These include recharge, hydraulic conductivity, fracture porosity, dispersivity and strength of matrix diffusion. The flow model is conceptualized to address the problem of density-driven flow under conditions of variable salinity and geothermal gradient. The conceptual transport model simulates the advection–dispersion process, the diffusion process from the high-velocity fractures into the porous matrix blocks, and radioactive decay.For this case study, the uncertainty of the recharge-conductivity ratio contributes the most to the output uncertainty (standard deviation of mass flux across the seafloor). The location of the freshwater–saltwater transition zone changes dramatically as this ratio changes with the thickness of the freshwater lens and the location of the seepage face changing as well. In the context of radionuclide transport from the nuclear test cavity that is located in the area where the transition zone is uncertain, travel times of radionuclide mass from the cavity to the seepage face along the seafloor are significantly impacted. The variation in transition zone location changes the velocity magnitude at the cavity location by a large factor (probably an order of magnitude). When this effect is combined with porosity and matrix diffusion uncertainty, the uncertainty of transport results becomes large. Although thermal parameters have an effect on the solution of the flow problem and also on travel times of radionuclides, the effect is relatively small compared to other flow and transport parameters.     

花岗岩介质中地下爆炸震源函数研究

结合地震反演方法和数值计算方法，研究了地下爆炸震源函数的特征以及介质特性对震源函数的影响。从水饱和花岗岩地下爆炸波数值模拟计算出发，重点分析了含水量对震源函数特性的影响。结果表明，含水量会提高地下爆炸的耦合强度，对于震源函数的稳态值，干岩要比水饱和岩石低，且稳态值随含水量的增大而增大；拐角频率随含水量的增大而降低；在水饱和花岗岩中，震源函数的高频衰减指数高于f-2；而过冲特性并不明显。     

Numerical investigation of convective heat transfer in liquid hydrocarbons stored in underground reservoirs

In planning for the underground storing of liquid hydrocarbons and calculating the technological parameters of underground reservoirs formed by leeching from a rock salt massif, it is necessary to understand the hydrodynamic and heat transfer processes produced by natural convection. The paper is devoted to numerical study of the initial stage of convective heat transfer in a vertical cylindrical cavity completely filled with a liquid hydrocarbon. It is assumed that at the initial time the temperature of the liquid, which is at rest, is homogeneous, Convective flow develops in part due to the initial temperature difference between the liquid and the massif and partly due to the geothermal temperature gradient in the latter. The problem is regarded as coupled, the convective process in the liquid being determined simultaneously with the solution of the heat-conduction problem in the surrounding rock. The Grashof numbers characterizing the intensity of the real process are very large: G lO¹²–lO¹⁵. A numerical solution was obtained for moderate Grashof numbers G lO⁷–lO¹¹. The asymptotic dependences for the integral characteristics of the unsteady process obtained in a series of calculations were extrapolated to the real values of the Grashof number.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 143–148, March–April, 1981.     

Large scale grain dust explosions-research in Poland

For the last five years grain dust explosion research was carried out in surface and underground facilities of Experimental Mine “Barbara” Research was focused on problems of evaluation critical dust parameters influencing explosion course, explosion development and suppression by both passive and active means. The main conclusions are as follows: nominal dust concentration needed to obtain flame propagation must be higher than 50 g/m³, for nominal concentrations higher than 100 g/m³ flame acceleration is observed and detonation is possible; strong grain dust explosions can be effectively suppressed with passive water barriers whereas for weak ones active barries must be used.     

露天爆破震动诱发地下洞室顶板失稳的非线性机理分析

开挖爆破是诱发工程岩体失稳的重要因素.根据露天与地下联合开采特点,将地下洞室顶板简化为水平简支梁,基于非线性理论分析方法建立了露天爆破震动扰动诱发地下洞室顶板失稳的突变理论模型,导出了其失稳判据条件和临界安全厚度,探讨了爆破震动幅值、主频、围岩特性等主要因素对地下洞室顶板临界安全厚度的影响.以甘肃厂坝铅锌矿群采空区顶板安全厚度分析为例,计算得到了露天与地下采场之间顶板的临界安全厚度.研究结果表明:露天爆破扰动诱发地下洞室顶板失稳过程具有非线性和不连续性特征,顶板临界安全厚度不仅取决于岩体工程特性,而且与爆破震动幅值、主频等多重因素有关,这与实际情况是吻合的.     

考虑半覆水圆弧相变场地特征的地下多点地震动模拟方法与程序开发

建立了同时引入土壤介质相变和半覆水圆弧地形因素的场地模型，并给出了地下多点地震动模拟的理论框架，开发了依据本文理论的程序并予以可靠性验证。首先，基于探明的波场分布得到了SV波入射半覆水圆弧相变场地的频域解；其次，获得依据频域解的场地传递函数并求解出地下自功率谱，建立了基于所得到的地下相干函数的地下互功率谱，由此构建出地下功率谱矩阵；最后，实现频域模型向时域信号转化（即多点地震动时程曲线），进而基于上述理论进行可视化程序开发。通过数值算例进一步阐明了本研究的意义，结果表明，（1）地下与地表多点地震动在能量分布上存在显著差异，说明了研究的必要性；（2）生成地震动的拟合功率谱和拟合相干函数与理论值吻合较好，表明了结果的合理性；（3）可视化程序界面简洁，参数输入及调整方便，后处理结果显示清晰，反映出程序的便捷及适用性。     

影响含硫化物的地下工程围岩中锚固体系侵蚀的主要因素研究(英文)

采用复合式衬砌的隧道及地下工程,锚喷支护系统的耐久性直接影响结构的稳定性和运营年限。锚杆主体属于钢构件,极易遭受侵蚀。从采用复合式衬砌的隧道及地下工程的结构特点可知,对于一定形式的锚杆,所遭受的侵蚀作用主要取决于锚杆与来自围岩的侵蚀性地下水的相互作用。本文探讨了含硫化物围岩中影响锚杆侵蚀的主要因素,描述了侵蚀性地下水的形成,以及锚杆侵蚀作用的物理化学机理,并提出了基于此机理的含硫化物围岩中锚杆使用年限的估算方法。     

不同类型地震波作用下地下综合体结构地震反应分析

为探究不同类型地震波作用下地下综合体结构的地震反应特征,本文以上海某地下综合体为工程背景,采用ABAQUS软件建立土-地下综合体结构相互作用体系三维有限元模型,利用Davidenkov模型模拟土的非线性,以不同类型的单向地震波和双向地震波（含水平向和竖向）作为输入,对软土场地中地下综合体结构进行了地震反应分析,比较了不同类型地震波作用下地下综合体结构地震反应的差异,探讨了地下综合体结构的竖向地震动效应问题．本文的算例结果表明：在长周期地震波作用下地下综合体结构的位移响应和内力响应峰值均明显大于普通地震波作用下的结果;考虑竖向地震动时地下综合体结构的柱轴力较单一水平向地震动作用情形有明显增大;在本文地下综合体结构算例中,地下三层柱底、四层柱顶、五层柱底、以及底板与侧墙连接处为受力较大部位．     

某大型水电枢纽坝基埋藏型岩溶发育特征及深层承压水研究

作者在现场工程地质勘察、试验基础上, 对我国西南某大型水电枢纽坝基所遇特殊的复杂埋藏型岩溶、承压水问题进行了研究, 弄清了坝基岩溶、承压水形成条件及发育特性, 对坝址选择及工程处理的决策具有重要意义。     

地下结构多尺度动力分析方法

近年地下结构震害频发,针对目前地下结构抗震研究中实际存在的多尺度动力问题,提出了地下结构多尺度动力分析方法,该方法不需要任何附加的过滤和阻尼就能有效地消除高频波的虚假反射. 以桥域耦合理论为基础,引入拉格朗日乘子将不同尺度区域之间的约束关系,通过能量势函数隐含到动力方程中,推导出不同尺度域的动力控制方程;基于中心差分法,提出了用于地下结构多尺度分析的动力显式算法,以求解所建立的多尺度动力耦合体系. 以实际工程为应用实例,通过与传统的位移耦合方法的对比分析,说明了该多尺度方法用于地下结构动力分析的可行性以及对消除高频波虚假反射的有效性.      

Numerical prediction of rock mass damage due to accidental explosions in an underground ammunition storage chamber

Accidental detonations in an underground ammunition storage chamber inside a rock mass may cause severe damage to the rock mass around the chamber, adjacent tunnels and chambers, ground surface, and in the worst case cause sympathetic detonation of explosives in adjacent storage chambers. To prevent such damage, underground ammunition storage chambers are often situated at minimum depth below the ground surface, and spaced at minimum distance from each other, so that damage, should it occur, is limited to the accidental chamber. Different codes and regulations for ammunition storage chambers specify minimum embedment depth and separation distance for underground ammunition storage chambers. They are usually given in terms of the rock mass properties and the weight of explosive stored in chambers. Some empirical formulae, usually based on the peak particle velocity of the stress wave or the maximum strain of the rock mass, are also available to estimate the damage zones in the rock mass from an explosion. All these empirical methods do not include the effects of explosion details, such as the loading density, chamber geometry and explosive distribution. In this paper, a previously calibrated numerical model is used to estimate the damage zones in a granite mass resulting from an accidental explosion in an underground ammunition storage chamber. Effects of various explosion conditions on rock mass damage are investigated. On the basis of the numerical results, some empirical formulae are derived to predict damage zones around the explosion chamber, as well as safe embedment depth of the storage chamber and safe separation distance between adjacent chambers. The numerical results are also compared with available empirical formulae and code specifications. It should be noted that the characteristics of stress wave propagation around an ammunition storage chamber has been published in a preceding paper (Int. J. Blast. Fragm. 5:57–90, 2001.     

有耗介质探地雷达波传播衰减特性的研究

探地雷达是利用超高频脉冲电磁波探测地下介质分布的一种浅层地球物理勘探方法,探地雷达超高频、宽频带脉冲电磁波在地下有耗介质中的衰减特性是一个十分复杂的过程。本文从电磁波传播的麦克斯韦方程出发,较为系统地研究和分析了雷达脉冲电磁波在有耗介质中传播的衰减特性,对研究雷达脉冲电磁波在地下有耗介质中的传播机制有指导意义。     

Dynamic response of underground structures by time domain SBEM and SFEM

The dynamic interaction problems of three-dimensional linear elastic structures witharbitrary shaped section embedded in a homogeneous,isotropic and linear elastic half spaceunder dynamic disturbances are numerically solved.The numerical method employed is acombination of the time domain semi-analytical boundary element method(SBEM)usedfor the semi-infinite soil medium and the semi-analytical finite element method(SFEM)used for the three-dimensional structure.The two methods are combined throughequilibrium and compatibility conditions at the soil-structure interface.Displacements,velocities,accelerations and interaction forces at the interface between undergroundstructure and soil medium produced by the diffraction of wave by an underground structurefor every time step are obtained.In dynamic soil-structure interaction problems,it isadvantageous to combine the SBEM and the SFEM in an effort to produce an optimumnumerical hybrid scheme which is characterized by the main advantages of the two methods.The     

Oil Plume Distribution in an Anisotropic Porous Medium

The saturation distribution—within an anisotropic aquifer—of a pollutant discharging from an underground source is modeled by a two-dimensional, nonlinear diffusion–convection equation. A closed form self-similar solution is obtained for the steady saturation distribution in the immiscible zone. The results may be used to rationalize field data collected for predicting locations of underground leakage sources in aquifers and to understand the influence of the anisotropic permeability’s parameters on the oil distribution in the porous medium. An erratum to this article can be found at     

Magnetic Dipole Moment from a One‐Kiloton Underground Nuclear Explosion in a Cavity

This paper reports the results of numerical modeling of the magnetic dipole moment produced by displacement of the Earth's magnetic field in a onekiloton underground nuclear explosion in a cavity. It is shown that with increase in cavity size, the magnetic dipole moment increases, reaching 10⁷ A · m², which is approximately 200 times the magnetic dipole moment from a camouflet explosion. A factor of 100 decrease in the initial air density in cavities with radii of 10 and 20 m results in a reversal of the direction of the magnetic dipole moment vector.     

Calculation of nonstationary transport of moisture for drip and underground irrigation

Nonstationary transport of moisture in the case of drip and underground irrigation is considered. In the first case, the tricklers are simulated by point sources of variable intensity; in the second case, linear sources are used. A three-dimensional model is used to study transport of moisture in unsaturated, homogeneously anisotropic media with allowance for underground sources of moisture absorption (the roots of plants) and the presence of sources of moisture simulated by pulsed Dirac delta functions. The basic equation is linearized by means of a Kirchhoff type ansatz. Expressions are obtained which, using known solutions for point, linear, or planar moisture sources of various geometrical configurations in an unbounded region, enable one to construct solutions for an arbitrary arrangement of these sources in a semi-infinite region with horizontal boundary coinciding with the surface of the ground.Translated from Izvestiya Akademli Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 74–81, July–August, 1981.     

二级高压驱动阵列弹珠同步弹射微型爆源的研制

针对当前大当量地下爆炸真空室模拟试验中爆源起爆方式高度依赖火药制品等问题，基于地下爆炸相似理论和二级气炮原理，自主研制了二级高压驱动阵列弹珠同步弹射微型爆源装置。装置利用二级高压气体驱动弹珠同步击碎玻璃球壳，释放球内高压气体，以模拟真实爆炸气体生成物的推出。整套爆源装置的发射参数:高压气室充气压力4 MPa，玻璃球壳内残余稳态气体压力约为3 kPa，能够用于0~20 kt当量地下爆炸成坑效应的真空室模拟。爆源适用性试验验证表明，该爆源装置的爆破机制和爆破效果满足大当量地下抛掷爆炸真空室模拟试验的功能需求，且具有较高的安全性、可控性和可操作性，为开展相关模拟试验提供了新的技术方法。     

Construction of the underground contour of a hydraulic structure with constant flow velocity sections

The underground contour of an embedded rectangular dam, whose corners are rounded in accordance with curves of constant flow velocity and whose water-permeable base is underlain by a confining layer with a curvilinear roof characterized by a constant flow velocity, is constructed. The corresponding boundary value problem is solved by means of the semi-inverse use of the velocity hodograph method. The results of the numerical calculations are given and the effect of the main determining parameters of the model on the shape and dimensions of the underground contour of the dam and the curvilinear confining layer is analyzed. The limiting cases in which the water-permeable base of the dam has an unbounded thickness, namely, a streamlined apron with a horizontal insert and streamlined sheet piling (tooth), are investigated in detail.     

岩土力学与地下工程结构分析计算的若干进展

本文扼要介绍了岩土力学和地下工程结构分析计算方面近年来的若干进展，主要只对作者在课题研究中所接触到的一些工作进行综合性阐述，而未求涉猎该一子学科领域中所有问题。本文的主要内容包括：岩土力学学科的若干进展；几种有前景的数值方法；计算机科学在岩土力学与地下工程中的采用和地下结构的抗震动力分析计算研究。