大型地下洞室群开挖模拟中的特殊现象分析

运用几种通用数值分析软件对一系列大型地下洞室群开挖模拟时，发现一种特殊现象——“反向位移现象”。本文首先对这种现象进行了详细的描述，然后分析了这种特殊现象出现的原因，并提出了相应的防止措施。     

煤层气产出过程中气—水两相流与煤岩变形耦合数学模型研究

气－水二相流和煤岩变形耦合作用是煤层气产出过程中一种复杂的物理现象，为准确描述这一现象，本文建立了气－水二相流和煤岩变形的微分方程，并用有限元分别将它们进行离散化，然后讨论了煤岩变形模型和气－水二相流模型进行耦合数值求解的方法。     

材料表面非线性振荡时间序列的相空间重构

在许多固态材料的表面存在着一种天然的非线性振荡花样，这些花样经计算机图像处理在时间和空间上呈现明显的分形特征。利用普通光学显微镜对Cu—Zn—Al合金表面的金相组织进行观察和分析，用高速摄像机拍摄了典型的振荡现象。借助计算机图像处理技术系统地研究该非线性振荡现象的形貌、结构特征及形成动力学规律，通过计算机编程技术构建系统的非线性动力模型，并重构系统的相空间。用R／S方法对系统时间序列的演化特征进行分析论证，结果表明，这种相空间重构方法具有较好的非线性预报效果。     

非共轴本构模型在地基承载力数值计算中若干影响因素的探讨

土体在剪切变形过程中产生主应力方向的旋转时,主应变增量方向与主应力方向之间存在着非共轴现象,然而传统的弹塑性本构模型未能考虑该现象的影响。通过在屈服面的切线方向增加一项非共轴塑性应变增量,即可实现对非共轴现象的反映。采用显式积分算法和自动分步方法,将非共轴本构模型运用到桶形基础地基承载力问题的有限元计算中,并讨论了流动法则、内摩擦角、膨胀角等因素与非共轴模型的联系。计算结果表明：采用有限元程序默认容许误差时,该本构模型可达到理想的收敛精度,并且,该模型对关联、非关联流动法则均适用。采用共轴模型进行数值计算时,不同流动法则对计算结果的影响可以忽略;采用非共轴模型时,不同流动法则的计算结果之间存在差异。非共轴现象对地基承载力-位移曲线具有软化作用,并且,该软化作用在采用非关联流动法则时变得更加明显     

基于分叉理论的岩体局部化现象研究

为了研究岩体局部化现象,基于轴向压杆稳定实例,运用数理和力学知识,根据Drucker-Prager（简称D-P）准则,推导了基于分叉理论的通用表达式。在此基础上,结合有限差分理论得出FLAC3D计算中岩体内发生分叉的判定条件,之后在自带的FISH编译语言的辅助下,在FLAC3D中建立数值分析模型,采用D-P本构关系,研究了岩体局部化现象及其发展过程。研究结果表明：在FLAC3D中以20 000步为间隔所得的不平衡力比率模型系统逐渐趋于稳定,不平衡力比率逐渐降低,局部化现象的规模逐渐扩大至稳定,清晰度逐渐增加,证实了分叉理论能够有效地分析研究岩体局部化现象。给出的岩体局部分叉判定条件和数值验证,较为科学合理地阐述了常用分叉判定条件的由来,为解释岩体局部化现象的机制和过程提供了理论支撑,从而对岩体局部化现象研究起到了一定的推进作用。     

山坡风化表层碎石爬行机理研究

山坡风化表层碎石爬行运动是存在于自然界、受多种环境因素影响的一种地表缓慢地质变形现象。本文在介绍有关现场试验测量方法的基础上,通过对测量数据和实地观察结果的分析研究,初步描述了这一自然现象的运动机理和存在的运动形式,并提出了对这一自然现象进行可能的力学、数学模拟研究的初步设想和尝试。     

Heat contamination in groundwater sourced from heat pump for heating in Bratislava (Slovakia)’s historic centre

The aim of the study is to evaluate the warming effect (thermal contamination) of city centres with high building density. This phenomenon has a number of scientific and practical implications. The case study was conducted in Bratislava (Slovakia), in the geological environment of alluvial gravels of the Danube River, where a permanent warming of the subsurface in the city centre is experienced, which is mainly affected by high building density and underground utilities. Thanks to this thermal contamination, the heat pumps efficiency is greater in winter, while in summer, their effectiveness is lower. Economically, this negative phenomenon in the case of heat pumps has a positive effect, since it increases energy efficiency during the heating period. This phenomenon is not universal and depends on the specific boundary conditions of the geological settings and hydrogeological conditions.     

海上地震资料处理中的潮汐静校正处理研究及应用

海水因为受月亮引力的作用会产生潮汐现象,在海上地震资料中表现为假断层现象,这种现象会影响地震资料的成像质量,导致错误层位解释及储层预测,因此在地震资料处理中,需要进行潮汐静校正处理。这里讨论了如何应用海上采集的高程值计算出地震波来回通过基准海平面与放炮时海平面之间的薄层水体所经历的时间,再将全部地震数据都校置在同一观察平面,从而实现潮汐静校正处理的方法,并应用于海上某工区中,得到较为理想的效果。     

固结过程中孔隙水压力计算中的吉布斯(Gibbs)现象及其消除

一维固结过程中，孔隙水压力的计算在整个计算中占有重要的位置，其计算结果的准确性对于固结度及固结系数的确定均有一定的影响。目前，孔隙水压力的计算均采用级数计算，而由于级数计算中Gibbs现象的存在，使得孔隙水压力的计算中会出现振荡。针对这种情况，本文以误差函数作为基础，对孔隙水压力的计算进行了分析，发现在一定的精度范围内，采用误差函数可以有效地消除由于Gibbs现象带来的振荡。     

Stochastic Modeling of Progressive Failure in Heterogeneous Soil Slope

Accurate and efficient simulation of the slope stability, certainly gives the reliable approach for the hazard preparedness. However, inherent difficulties associated with the slope failure make the situation very difficult. First, the computation of fracture path based on the strict mathematical formalism is cumbersome especially for the progressive failure phenomenon. Second, due to the lack of reliable knowledge on material properties, stochastic simulation is necessary. Stochastic modeling together with the progressive failure phenomenon is apparently difficult task. In this paper, heterogeneous slope is simulated considering the progressive failure phenomenon using the modified finite element method introducing the fracture along the edge of the meshes thus incorporating the time evolution of the fracture surface. This is achieved by restructuring the tessellation in every fracture stage. Unlike remeshing this technique only increases the number of total nodes while number of meshes remaining same, which is simple and natural. Further, in this research, effect of uncertainty in the material properties upon the uncertainty in the response of soil slope has been evaluated, hence giving the reliable probabilistic estimation of the factor of safety, failure surface and deformation of the slope. Thus the simulation based on the more reliable understanding of the material properties and the efficient numerical procedure for the progressive failure phenomenon can give the reliable result of the simulation for the heterogeneous soil slope thus enabling the more accurate way for hazard preparedness.     

一种新的钻井液静失水量方程

实验室测试钻井液的API失水量结束后,仪器内剩余钻井液的粘度比测试前有所增大。为了解释这一现象,对原钻井液静失水量方程推导中所采用的渗滤模式提出了不同看法,以一种不同的渗滤模式为基础提出了新的钻井液静失水量方程,此方程可以解释这一现象。依照此方程,实验室测试API失水量时仍然可用7.5 min失水量的测试结果乘以2得到的数值代替30 min失水量的测试结果。      

有限单元法模拟地下水流的水头反常现象——对流量计算的作用

地下水流数值模拟是定量研究地下水水量和水质的重要手段。为揭示有限单元法水头反常现象形成的原因,以三维非均质模型为例,刻画了水头反常现象。储量集中法(Lumped Mass方法)是有限单元法中储释水量计算的替代算法,可以改善水头反常现象。对结点控制区域的均衡性质进行了研究,分析了使用Lumped Mass方法时的水头反常现象,结果表明:结点控制区域的对流量计算受到该结点所在层及其相邻层水力坡度的影响;在抽水初始阶段,抽水井结点水头快速下降,导致相邻层中相邻结点控制区域的侧向流入量为正值,控制区域为储水过程,结点水头上升,表现出水头反常现象。因此,有限单元法中对流量的计算是引起水头反常现象的原因。     

一种"静校不静"现象的分析

在我国西部地区由于表层激发接收条件差, 常采用高叠加次数的地震观测技术。在地震数据处理中, 在进行了地形校正和基准面校正之后, 还存在数十毫秒的剩余静态时差。在叠加剖面上, 这种静态时差对反射波的起伏形态的影响具有浅中深层的差异性, 即出现了"静校不静"的现象。分析表明 , 这种现象是由叠加次数高、排列偏移距大, 在同一个CMP道集中, 浅、中、深层参加叠加的道数差异较大, 导致叠加过程中对静态时差平滑作用的差异所致。与岩石裸露山区中因反射波传播路径差异形成的非地表一致性"静校不静"现象不同, 仍然是"地表一致性"的。分析产生这种现象的原因, 为正确进行静校正打下基础。     

多孔介质中水敏性应用的研究综述

水敏现象在石油、岩土和环境工程等领域广泛存在。有效地控制水敏现象的发生，不仅具有科学意义，还有一定的经济价值。本文在广泛查阅国内外研究成果的基础上，总结了水敏性在石油、岩土和环境工程方面应用的研究进展，并在此基础上提出了水敏性研究的发展方向。     

Planning development towns in Kuwait

Kuwait has been characterised by the emergence of a dominating metropolitan center in the last two decades. The new phenomenon led to severe regional imbalance because investments and development programs concentrated around the metropolitan center of Kuwait. To alleviate problems associated with such a phenomenon, to improve urban life, and to achieve regional balance, the country must plan for establishing new towns.This paper is divided into three sections. The first section identifies and discusses the major factors which contributed to the phenomenon of metropolitan dominance. The identified factors are: oil wealth, immigration and population growth, sectoral expansion, i.e. governmental services, the housing sector, commercial activities, industrial growth, and the road network. Discussions in the second section emphasized the different patterns of urban growth and expansion in Kuwait. Four patterns of urban development are identified in this section. The third sections deals with the necessity of town development in Kuwait in light of the growing phenomenon of metropolitan dominance. To evaluate the potentials of town development in the country, four major factors are stressed in this study. They are: planning, size and location, cultural aspirations, and leadership.This is a revised version of an original paper presented at the 77th Meeting of the Association of American Geographers held in Los Angeles, April 1981     

The critical scale of fluctuation for active lateral forces in spatially variable undrained clays

This study addresses the phenomenon of the critical scale of fluctuation (SOF) for active lateral force (P_a) in undrained clay when there is a spatial variability in the clay. The phenomenon is significant under shear strength (τ_f) random fields but is insignificant under unit weight (γ) random fields. It is found that the phenomenon of the critical SOF is connected to the nature of the spatial averaging, which is “line averaging” under τ_f random fields and is “area averaging” under γ random fields. The former averaging effect (line) is significantly weaker than the latter (area), so the tendency for the critical slip plane to seek for a favorable location is stronger for the τ_f random field than for the γ random field. Hence, the phenomenon of the critical SOF is more pronounced under τ_f random fields than under γ random fields. The underlying mechanisms for the phenomenon of the critical SOF will be explored in this paper.     

脉冲性电磁法物探信号的频谱分析

电磁法物探的勘测信号,在不同频率段,存在不同的信号脉冲现象.通过小波时频分析功能,可以对脉冲现象进行分析.研究表明,脉冲现象严重影响基于傅立叶变换方法的解译效果,脉冲现象严重时,傅立叶方法已不适用.     

粤北岩溶石山地区石漠化现状及其对水环境的影响

粤北岩溶石山地区生态地质环境条件脆弱,成壤能力及水土涵养能力极低.岩溶分布区石漠化现象较为突出,并日益严重.全区现状石漠化面积为2 343.21km^2,占碳酸盐类岩石分布面积的21.8%.本文根据该地区的水文地质与环境地质调查资料,结合遥感解译成果,研究了区内石漠化分布现状及其成因,并探讨石漠化现象及其发展对水环境的影响,为石漠化的综合治理规划提供了科学的资料和依据.     

El Ni?o as a consequence of the global oscillation in the dynamics of the earth’s climatic system

During study of the physical nature and potential precursor features of the El Ni?o phenomenon in the Pacific, it was found that a negative large-scale temperature anomaly on the Indian Ocean surface may be one of its significant precursors. This anomaly appears prior to the occurrence of El Ni?o and is accompanied by growth in atmospheric pressure. It gradually extends eastwards along the equator until the zone of planetary convection in the area of the Indonesian Region. The west wind that emerges on the eastern peripherals of the mentioned pressure anomaly leads to reversal of the Pacific segment of the Walker equatorial atmospheric circulation and to a subsequent change in the zonal thermal dipole polarity in the tropical zone of the Pacific (the latter means culmination of the El Ni?o phenomenon). In addition to the mentioned thermobaric anomaly in the Indian Ocean, other obvious signs of large-scale pressure anomalies have been found in the global atmospheric pressure field; these anomalies may be interpreted as manifestations of the intradecadal global oscillation in the dynamics of the modern climatic system. It is suggested that the whole known complex of events related to the El Ni?o phenomenon in the Pacific is a consequence and a regional link of the planetary structure of this global atmospheric phenomenon.     

An Interpretation of the Origin of Distribution Anomalier of △C

Zonal distribution of seepage hydrocarbon-induced altereb carbonates over oil/gas reservoirs is a common phenomenon observed in the field.The authors considered that the continuous production of CO2 within the “alteration chimney ”gives rise to a significant difference in physical and chemical properties between its interior and the surrounding country rocks.And it is this difference that has promoted the erosion and precipitation of carbonates,thus leading to the zonal distribution of seepage hydrocarbon-induced altered carbonates over oil/gas reservoirs.This may be a reasonable interpretation of the phenomenon described above.