Mechanics and fluid transport in a degradable discontinuity

This paper briefly examines the mechanical and hydraulic response of discontinuity in a geologic medium that can experience degradation of its contacting regions due to shear and normal stresses acting on it. The paper discusses the methodologies that can be adopted to describe the mechanics and fluid transport behaviour of such a joint. The calibration capabilities of the model are illustrated by appeal to a comparison of experimental results with computational predictions.     

利用图像数字化技术分析冻结缘特征

以开放系统饱水正冻土为研究对象,作不同土质和不同初始条件下的单向冻结实验。实验结束后立刻对试样做复形膜。随后将复形膜进行图像数字化处理,可反演分析冻结缘和冰分凝形成的时间、厚度、位置及冻结缘导湿系数。结果表明,图像数字化技术具有较高的分析精度和准确性,是一种实用的创新研究方法;在给定的试验条件下,冰分凝速度随试验持续时间呈幂函数形式减小。冰分凝温度在试验初期随冻深快速推移而降低,随后由于冻土段长度     

Interpretation of long-offset transient electromagnetic data from the Odenwald area, Germany, using two-dimensional modelling

The standard 1-D inversion approach for the interpretation of transient electromagnetic (TEM) data usually fails in the presence of near-surface conductivity anomalies. Since multidimensional inversion codes are not routinely available, the only alternative to discarding the data may be trial-and-error forward modelling. We interpret data from a long-offset transient electromagnetic (LOTEM) survey which was carried out in 1995 in the Odenwald area, using 2-D finite-difference modelling. We focus on a subsegment of the LOTEM profile, which was shot with two different electric dipole transmitters. A model is found which consistently explains the electric and magnetic field data at eight locations for both transmitters. First, we introduce a conductive dyke under the receiver spread to explain sign reversals in the magnetic field transients. A conductive slab under one of the transmitters is required to obtain a reasonable quantitative fit for that transmitter. Consideration of the electric field data then requires a modification of the layered earth background. Finally, we study the response of a crustal conductor, which was the original target of the survey. The data are sensitive to the conductor, and for the investigated subset of the data the fits are slightly better without the conductive layer.     

Short Note: Effective Hydraulic Conductivity and Transmissivity for Heterogeneous Aquifers

Regional scale models of groundwater flow and transport often employ domain discretizations with grid blocks larger than typical scales of field data. For heterogeneous formations, this difference in scales is often handled by using effective (upscaled) parameters. We investigate the problem of upscaling hydraulic conductivity and transmissivity from a small scale of measurement to a larger scale of grid blocks. Transmissivity statistics is expressed in terms of statistics of hydraulic conductivity, and expressions for the effective (upscaled) hydraulic conductivity K _eff and transmissivity T _eff for steady state flow in confined heterogeneous aquifers are derived by means of stochastic averaging and perturbation analysis. These expressions reveal that the commonly used relation T _eff = BK _eff, where B is the confined aquifer thickness, is not generally valid.     

GIS-Based Hydrogeological-Parameter Modeling

INTRODUCTIONHydraulic conductivity is one of the most important pa-rameters of surficial deposits for hydrogeological study.At awatershed scale,the hydraulic conductivity changes verticallywith decreasing downward from the earth surface and horizon-tally from lithological unit to lithological unit. The verticalvariation of conductivity can be described by hydraulic conduc-tivity decay factor that describes the exponential decay of hy-draulic conductivity with the depth of the considered- p…     

0.5～1.5GPa下石膏脱水过程动态监测电导率法

在 0 .5～ 1 .5GPa,1 60～ 2 55℃条件下动态监测了石膏脱水过程中电导率随时间的变化。实验结果表明 ,脱水过程中电导率随时间的变化分两个阶段 :第一阶段电导率随时间的变化速率可间接地反映脱水反应的速率 ;第二阶段反映了流体中溶解离子的增多。相角随时间的变化可动态反映释放的水在矿物颗粒边缘的存在及连通性。电导率法是适用于含水矿物脱水过程动态监测及脱水过程中水的分布、迁移等动力学过程就位研究的有效方法。     

地质雷达的应用条件探讨

地质雷达是浅部勘探的一种有效的勘探方法。本文对其应用条件进行了探讨,特别研究了导电率、介电常数、探测频率3个主要因素对地质雷达探测的影响。研究结果对地质雷达的应用具参考指导作用。     

基于电导率测定海水悬沙含量试验研究

为了寻求一种简单、快速、连续确定悬浮泥沙含量的方法,以高含沙量海区黄河口泥沙为研究对象,利用电导率仪测定了不同悬浮泥沙含量水体的电导率,建立起了悬浮泥沙含量与电导率之间的关系,并对影响上述关系的因素进行了分析,结果表明,悬浮泥沙含量与电导率之间有很好的线性关系;盐度、颗粒粒径对电导率具有一定的影响,其中盐度的影响最大,颗粒粒径的影响较小。在盐度变化范围有限的高悬沙含量海区,用电导率的方法来实现现场监测悬浮泥沙含量是可行的。     

深海沉积物热流原位、快速探测技术

热流探测技术的应用对研究海洋地壳活动规律、防灾减灾与天然气水合物新能源探测具有重要意义.论文对海底热流原位探测技术作了全面的介绍,分析了温度梯度与热导率原位、快速测量的发展现状,指出了我国未来发展海底热流探测技术急待解决的问题.