重力矢量及张量信息在地球重力场中的应用

随着重力测量技术日新月异的发展，尤其是空间重力测量技术的发展，使反映地球中、高频信息的重力矢量及张量的获取成为可能。文中建立了基于重力矢量及张量信息求解重力场中扰动场元的数学模型，对于将来重力场的精化及其时变性的研究具有一定的理论意义。     

浅析甘肃省某金矿开发中应注意的几个问题

甘肃省某金矿区属高中山地貌区,主要岩石为千枚岩,构造以NWW向断裂为主,矿区水文地质条件简单,工程地质条件中等。采矿区、工业场地、尾矿库等矿山建设可能诱发或加剧地质灾害,应进行相应的防治工作,同时对矿坑排水及生产废水进行有效处理,防止污染水环境。     

渗流场随机性的随机有限元分析

基于一阶Taylor随机有限元法,推导出相应的渗流场随机分析中渗流响应量（水头和水力梯度）的随机响应公式,进而实现三维稳定渗流场随机有限元分析,并编制了相应的程序。在分析中,将渗流区域材料的渗透张量视为三维各向异性随机场,利用三维可分离向量随机场的局部平均法对随机场进行离散,根据参数选取的不同,可以离散出不同数量的随机变量。最后,给出一个算例,对离散出随机变量数量不同的情况分别进行随机分析,将分析结果和仅仅将渗透张量视为三维随机变量得到的结果对比,验证了所提方法的可行性。     

长沙电力学院3号教学楼人工挖孔灌注桩工程地质问题及其处理措施

长沙电力学院 3号教学楼人工挖孔桩基的施工条件极差。经灵活采用多种经济实用的措施处理 ,成功地解决了流砂、流泥、管涌、坍塌、护壁吊烂与整体失稳等技术难题。     

地球弓激波及其与行星际激波相互作用

给定地球轨道附近的行星际条件和地球弓激波的几何位形,本文分析向阳侧弓激波强度参数沿激波阵面的分布,以及行星际激波与弓激波的相互作用.对于弓激波阵面相对日地连线轴对称的情形,得到如下结论：（1）弓激波强度参数分布相对由行星际磁场和日地连线构成的基准面对称,各激波强度参数的最大值出现在基准面上.磁压比在垂直激波线一侧较大,而气压比在平行激波点一侧较大,导致总压比相对日地连线大致呈轴对称分布.（2）随着行星际磁场与日地连线夹角的增大,弓激波强度参数的最大值有所减小,且位置朝远离日下点方向偏移;但气压比和总压比的分布基本上不受影响.（3）行星际激波透过弓激波之后,切向磁场比更接近于1,但总磁场跳变幅度增大.（4）透过弓激波之后,行星际准垂直激波的总磁场比更接近于1,准平行激波的总磁场比则反之.     

地质找矿改革发展面临的突出问题与对策

国有地勘单位的改革始于20世纪末,以原地矿部所属的地勘队伍以及工业部门所属的大部分地勘单位属地化为标志,国有地勘单位开始了企业化进程。国家一系列优惠政策,给地勘单位的发展注入了新的活力。国家在加大对地勘单位投入的同时,放开了民营资本进入地勘市场的限制,商业性地勘市场出现了前所未有的繁荣,并取得了一大批重要的地质找矿成果。但国民经济的快速发展及国际矿业巨头的垄断,致使国内矿产品供需矛盾日益突出,经济发展对地质技术保障能力的要求被迅速放大,同时地勘单位体制机制的不和谐性也显现出来,具体表现为:勘查体制不顺、找矿机制不活、政策落实不够、勘探能力不强等。针对上述突出问题,提出了完善勘查体制、创新找矿机制、推进政策落实、提升勘探能力等相应的对策。     

Sinusoidal oscillations radiating from a cylindrical source in thermal conduction or groundwater flow: Closed‐form solutions

The diffusion equation governs thermal conduction and groundwater flow phenomena. In this paper, we study the two‐dimensional radial propagation of a sinusoidal perturbation radiating from a cylindrical source within an infinite slab of homogeneous material. The solution of this problem has several applications. For instance, it can be used to determine the hydraulic diffusivity of the subsurface based on measurements of the hydraulic head around a vertical well during its development. For thermal problems, it can be used to determine the thermal diffusivity based on measurements of the temperature distribution around a cylindrical heat source generating a sinusoidal power per unit length. In this paper, we present a comprehensive analytical solution of this problem and we compare these solutions with numerical solutions. Two approximate analytical solutions, which can be relevant in practice, are also presented. Finally, we give an upper bound for the survival time of the transient part of the solution and we provide an estimate of the radius of influence of the sinusoidal solicitation. Copyright © 2010 John Wiley & Sons, Ltd.     

Characterization of fractured reservoirs using a consistent stiffness‐permeability model: focus on the effects of fracture aperture

In this paper we propose a method for the characterization of naturally fractured reservoirs by quantitative integration of seismic and production data. The method is based on a consistent theoretical frame work to model both effective hydraulic and elastic properties of fractured porous media and a (non‐linear) Bayesian method of inversion that provides information about uncertainties as well as mean (or maximum likelihood) values. We model a fractured reservoir as a porous medium containing a single set of vertical fractures characterized by an unknown fracture density, azimuthal orientation and aperture. We then look at the problem of fracture parameter estimation as a non‐linear inverse problem and try to estimate the unknown fracture parameters by joint inversion of seismic amplitude versus angle and azimuth data and dynamic production data. Once the fracture parameters have been estimated the corresponding effective stiffness and permeability tensors can be estimated using consistent models. A synthetic example is provided to clearly explain and test the workflow. It shows that seismic and production data complement each other, in the sense that the seismic data resolve a non‐uniqueness in the fracture orientation and the production data help to recover the true fracture aperture and permeability, because production data are more sensitive to the fracture aperture than the seismic data.     

反演模型分辨率的估算方法

反演问题的时空间分辨率或称时空分辨长度是评估模型精细程度的重要参数,决定了该模型应用的范围和价值,但是分辨长度估算却是比反演更复杂和麻烦的数学问题。除了层析成像中广泛利用理论模型恢复试验定性提取空间分辨长度外,通过求解分辨率矩阵可定量获得分辨长度。通过矩阵操作给出的分辨率矩阵包括三类:直接分辨率矩阵、正则化分辨率矩阵和混合分辨率矩阵。这三类矩阵包含了反演本身不同侧面的信息,因此在一个反演应用中,同时提供这三类分辨率矩阵可更全面地评估反演模型分辨率分布。最近An(2012)提出了从大量随机理论模型及其解中统计出分辨率矩阵的方法。这种分辨率矩阵是从模拟真实反演实验的输入和输出模型中通过反演得到的,因此这种分辨率矩阵更能反映整个反演所涉及到的更多因素和过程;同时由于这种分辨率矩阵计算过程无需进行矩阵操作且不依赖于具体正演和反演方法,因此可以被应用于更普遍的反演问题。实际应用证明统计分辨率分析方法适用于对二维和三维层析成像反演模型进行分辨率分析。     

The variable projection method for waveform inversion with an unknown source function

This paper compares three alternative algorithms for simultaneously estimating a source wavelet at the same time as an earth model in full‐waveform inversion: (i) simultaneous descent, (ii) alternating descent and (iii) descent with the variable projection method. The latter is a technique for solving separable least‐squares problems that is well‐known in the applied mathematics literature. When applied to full‐waveform inversion, it involves making the source wavelet an implicit function of the earth model via a least‐squares filter‐estimation process. Since the source wavelet becomes purely a function of medium parameters, it no longer needs to be treated as a separate unknown in the inversion. Essentially, the predicted data are projected onto the measured data in a least‐squares sense at every function evaluation, making use of the fact that the filter estimation problem is trivial when compared to the full‐waveform inversion problem. Numerical tests on a simple 1D model indicate that the variable projection method gives the best result; actually producing results in quality that are very similar to control experiments with a known, correct wavelet.