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。     

Semi-analytical solutions for soil consolidation induced by drying

Acta Geotechnica - Drying induced consolidation is ubiquitous in nature, yet no theoretical model is available to delineate this phenomenon. Fundamentally, this phenomenon is a multi-physical...     

厄尔尼诺现象及其对我国水文气候的重大影响

在简要介绍厄尔尼诺产生的背景、征兆、现象的基础上,分析了厄尔尼诺现象对全球及我国气候的影响,指出厄尔尼诺是一种自然现象,气候的形成受多方面因素的作用,厄尔尼诺对气候的影响是十分复杂和难以准确预测的,要加强对厄尔尼诺现象的监测和预测,预防和减少厄尔尼诺现象给人类带来的损失。     

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.     

阿克苏地区的一种特殊地质现象

在新疆阿克苏柯坪—巴楚314国道路碑标记1 145.5 km处二号硫磺沟发现了一种现代的特殊地质现象:这种现象的构造形态主要呈圆台状,其上部是块状灰岩或胶结程度较高的泥砾,下部由地层风化剥蚀物组成,它们像是从地面长出来的竹笋,所以就把这种特殊的地质现象称为泥笋。到目前为止,在该地区还没有人报道过这种现象。它是一种有成因和演变意义的地质现象。通过对其形成条件及过程的研究得出这种特殊地质现象的发育环境是水文过程和气候演变的记录。所以,对它们的研究,对研究当地现代气候具有一定意义。     

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。     

“未熟油”与“未熟生烃”异议

有关专家认为,“未熟生烃”是我国新生代盆地广泛存在的地球化学现象,本文剖析了这一论点背后隐含的矛盾,并以苏北盆地部分断陷中存在的“不等深等温”“不等深等熟”,成熟度指标与埋深关系的“平行变浅”分布等资料为依据,提出此现象当源于“古大于今”埋深史这一特定地质背景（或称为退化受热史）若以恢复的最大古埋深重新勾画产经曲线,所谓“低温早熟”现象即可消除,既然未熟生烃现象不存在,也就不存在未熟的石油,同时指     

Compaction localization in the Earth and the laboratory: state of the research and research directions

Localized compaction in porous rocks is a recently recognized phenomenon that has been shown to reduce permeability dramatically. Consequently, the phenomenon is relevant to a variety of technologies involving fluid injection or withdrawal. This article summarizes current understanding of localized compaction and impediments to further progress. The article is based on discussions at a small workshop on localized compaction sponsored by the Office of Science, U. S. Department of Energy.     

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     

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.     

木寨岭板岩隧道塌方的结构失稳分析及预防措施研究

目前国内已有较多穿越板岩地层的隧道工程,由于板岩的独特性质,板岩隧道工程问题多发,塌方是较为频发的现象之一。通过对木寨岭隧道塌方现象的分析,研究板岩隧道塌方的工程特征及影响因素,在此基础上运用板的稳定理论探讨板岩塌方现象的发生机制,结合实例进行分析,提出预防塌方现象的关键措施,并通过现场实际效果进行检验。结果表明,板岩的层状特性及初期支护跟进的不及时是发生塌方的根本因素,预防塌方现象应从这两点加以入手。木寨岭隧道后续施工的顺利进行,证明对于板岩隧道塌方原因的认识及预防措施的选取较为准确,对类似隧道工程塌方的预防及治理有一定的借鉴和参考意义。     

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.     

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。     

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.     

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。     

单向冻结时土颗粒位移的热筛效应及对流迁移

自然界中不同粒径上颗粒的随机组合造成土体中孔隙分布的随机性。土体冻结时，由于不同孔径中水分势能的差异，导致孔隙不冻结在时间上的有序性，即在相同温度下，粗大孔隙中水分首先冻结，然后逐渐向细小孔隙发展。水分冻结体积膨胀，从而引起粗颗粒土向上抬升，称为热筛效应。     

Dislocation substructures of grain boundaries on splitting surfaces of quartz rocks

Periodic microtopographic features have been observed on quartz rock splittings, a phenomenon that has not been observed before. Electron microscopy has made it possible to state that the character of distribution of the microrelief details (ditch-like and step-like features) is indicative of distribution of intercrystallite boundary dislocations. The phenomenon depends on dislocation properties and may substantiate the study of dislocations and grain boundaries.     

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。     

不同岩性顶板回采工作面矿压分布规律

采用数值模拟技术和现场矿压观测系统,研究了不同岩性顶板回采工作面矿压分布规律及其显现特征。结果表明,在煤炭开采过程中,不同岩性顶板回采工作面最大支承应力存在一定差异,在强度较高的砂岩顶板岩体中,支承压力大,工作面前方支承压力峰值距工作面距离小,初次来压步距和周期来压步距大,矿压显现强烈;而在强度较低的泥岩顶板区,顶板岩体不能和砂岩骨架层一样抵抗覆岩压力,且支承压力小,支承压力的峰值向回采工作面前方岩体内部推移,初次来压步距和周期来压步距小,矿压显现不明显。      

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。