岩土体物理力学参数对岩质滑坡稳定性的影响

采用有限元-极限平衡法研究了含软弱滑动带的岩质滑坡滑动体、滑动带和滑床的密度、弹性模量和泊松比及滑动带的抗剪强度对滑坡稳定性的影响。结果表明:滑床密度、滑体及滑动带的弹性模量、滑动带及滑床的泊松比和滑动的抗剪强度指标与滑坡稳定性系数呈正相关关系,而滑体及滑动带土体密度、滑床的弹性模量和滑体的泊松比与滑坡稳定性系数呈负相关关系;软弱滑动带的抗剪强度对滑坡稳定性的影响最显著,其次为软弱滑动带的泊松比和滑床的弹性模量,其他参数的影响相对较小。      

分析汶川“5•12”震害探求房屋“大震不倒”途径

本文围绕“大震不倒”主题,对汶川“5．12”特大地震震害进行了分析探究。文中涉及“大震不倒”设防目标、研究方法、房屋倒塌的震害特点等问题;对倒塌房屋分为薄弱层垮塌、沿开问垮塌、不规则体型垮塌3种类型进行了讨论,分析了垮塌的原因并提出了看法;同时还对“强梁弱柱”现象做了分析。最后,扼要对混凝土框架结构和砖混结构提出“大震不倒”的建议性意见。     

不良地质段双洞交叉开挖三维有限元分析

积石峡水电站泄洪洞与导流洞交叉段形成了跨度为28 m,高度为22 m类似城门洞形的大断面洞室,该洞段围岩呈层状分布,且有一软弱夹层穿过拱顶,对洞室稳定极为不利。针对这一实际工程问题,确定了开挖方案和支护措施,采用三维非线性有限元分析了该处的围岩应力和变形随开挖进行的变化和围岩的稳定性,并考虑了位于拱顶的软弱夹层对交叉段洞室开挖围岩稳定的影响,对于其他类似工程,其结果具有良好的参考价值。     

A three-dimensional model study on ocean dynamic response to traveling cyclone over the Huanghai Sea

On the basis of numerical simulation of the mean circulation and relevant thermal-salinity fields in June with a three-dimensional ocean model (ECOM-si), the model outputs are used as first guess of initial fields for numerical integration of the model equations and the numerical results are applied to investigating the dynamical responses of the Huanghai Sea and the East China Sea (HECS) in the course of a weak land-to-sea cyclone‘s passage over the Huanghai Sea on 15-16 June 1999. Predominance of the dynamic impact of cyclone over the thermal one in June in the HECS is justified using observations and model simulations.The cyclone and its surrounding weather system, i.e,, subtropical high ridge to its south could influence current and thermal fields in the Bohai Sea, the Huanghai Sea and the northern East China Sea even though the intensity of cyclone was rather weak. The response of oceanic currents to the wind stresses driven by the cyclone and its southern subtropical high were strongly characterized by the wind drift with its extent of equivalent scale of cyclone in the horizontal and of Ekman layer in the vertical. The sea response at a given site was closely related to the transient local wind speed and direction,especially was sensitive to the local wind direction,which is demonstrated at three points locating at the southern and western Huanghai Sea and the northern East China Sea. So the sea responses at locations differed considerably from one another. Current responded to the wind stress in a simple way:directly to the wind-driven current and subsequent gradient current and slope current, etc., whereas sea temperature responded to the wind stress in two ways: directly to the cyclone-induced cooling and indirectly to water movements both in the horizontal and the vertical by the cyclone‘ s wind stress. So the sea temperature variation under the influence of cyclone was more complicate than the current. The HECS in response to the cyclone and its ambient weather system was likely to be a fast process and such a response could last at least for more than 1d. Current increased with the duration of wind stress exerted on the surface and decreased with the increasing depth. Affected by the cyclone, the maximum sea surface temperature decreased by almost 1.6℃ during the 24h cyclone.     

Study of site effects in the area of Nocera Umbra (Central Italy) during the 1997 Umbria-Marche seismic sequence

During the M_L = 5.6 and 5.8 earthquakes occurredin central Italy on 26 September 1997 the historiccentre of Nocera Umbra, lying on top of a 120 m highhill, was diffusely damaged (VII-VIII degrees of MCSintensity). Some recently built houses in the modernpart of the town suffered an even higher level ofdamage. A temporary seismic array was deployed toinvestigate a possible correlation between localamplifications of ground motion in this area and theobserved pattern of damage. After a geologic andmacroseismic survey, eight sites were selected asrepresentative of different local conditions, such astopographic irregularities, sharp hard-to-softlithology transitions, alluvium-filled valleys, andboth undisturbed and deformed rocks.Horizontal-to-vertical spectral ratios for bothmicrotremor and earthquake recordings, as well asspectral ratios referred to undisturbed rock sites,were used to quantify local variations of groundmotion. In spite of the diffuse damage in the historiccentre of Nocera Umbra, a small amplification isobserved at the stations on the hill's top. Thissuggests that the higher vulnerability of the ancientbuildings mainly accounts for the diffuse damage inthat part of the town. In the frequency band ofengineering interest (1 to 10 Hz) the largestamplifications of ground motion are found at softsites: in the Topino river valley, where many episodesof severe structural damage occurred, spectralamplification is significant over a broad frequencyband ranging from 2 Hz to more than 20 Hz. Inparticular, in the central part of the valley highamplification (> 4) is found from 3 to 10 Hz,reaching a maximum of 20 around 4 Hz. At the edge ofthe valley, close to the soil-to-rock transition,amplification is as large as 10 in a frequency bandranging from 4 to more than 20 Hz. A significantamplification (by a factor of 10 around 10 Hz) isobserved also at one of the rock sites, possibly dueto the presence of a cataclastic zone related to theactivity of a regional fault that altered themechanical properties of the rock.     

地质作用的自组织临界过程动力学——地质系统在混沌边缘分形生长(下)

笔者对复杂性科学中的自组织临界性、瞬态混沌、混沌边缘和弱混沌四大理论和研究领域就其发展现状和最近动态作系统和深入的剖析后得出结论 ,认为以上四者是对自然界中开放、远离平衡、相互作用的巨大耗散动力学系统的时空演化这个统一事物的本质的面面观。笔者进一步将四者的相互关系归纳成一个重要的命题 :自然界中开放、远离平衡、相互作用的巨大耗散动力学系统的时空演化服从“自组织临界过程动力学” ,并且系统“在混沌边缘分形生长”。地质系统是自然界中的一种既十分重要 ,又异常复杂的开放、远离平衡、相互作用的巨大耗散动力学系统。它具有自组织临界性的内禀基本属性。它的时空行为服从地质作用的自组织临界过程动力学。地质系统位于有序和混沌之间的过渡时空域 ,即混沌边缘 ,其中系统呈规则与混沌运动并存和混合的弱混沌动力学状态 ,并且地质系统在混沌边缘分形生长。将上述命题演绎和整合成一种广泛适用于地质系统的地球科学的复杂性理论 ,名之为 :“地质作用的自组织临界过程动力学———地质系统在混沌边缘分形生长” ,并将其内容归纳成 6部分 :(1)自组织临界性、瞬态混沌、混沌边缘和弱混沌 ,(2 )多组分的耦合与相互作用及其相干与协同 ,(3)演化过程的分形动力学 ,(4 )作用的时空结构 ,(     

中蒙强、弱沙尘暴年春季平均环流及沙尘活动变化分析

利用NCEP/NCAR再分析资料,对比分析了中蒙东、中及西区强、弱沙尘暴年春季(3—5月)平均环流的特征和差异,讨论了过去50年3分区沙尘暴活动的变化。主要结论是:(1)根据诱发沙尘暴的诱生系统、沙尘源地、冷空气入侵路径及主要影响,中蒙沙尘暴活动区可以划分为中蒙东区、中区及西区3个区系,并分区整体讨论与预测中蒙3分区的沙尘活动。(2)中蒙东区沙尘暴强年春季盛行日本海或中国东北低压活动,常随偏东的北路及东北路冷空气入侵,带来蒙古国东部的沙尘,造成蒙古东部及中国华北的沙尘天气;而弱年春季日本海及东北低压活动则少。(3)中蒙中区沙尘暴强年春季盛行蒙古低压,多西北路及偏西的北路冷空气入侵,常造成中蒙南边界西段附近的沙尘暴天气;而沙尘暴弱年春季则相反。(4)中蒙西区沙尘暴强年春季盛行南疆热低压,多西路冷空气入侵,诱发沙尘暴,常影响南疆及柴达木盆地等;弱年春季则相反。(5)近50年中蒙地区的沙尘暴活动呈波动变化,荒漠化环境、特别是大气环流的变化是导致上述3个分区沙尘活动波动变化的主要原因。主要从大气环流角度考虑,在目前全球增暖持续的背景下,近1—2年应注意中、东区(特别是东区)沙尘活动加强的可能性。     

锦屏一级水电站引渠内侧自然边坡的稳定性

层状岩体顺层滑动但却存在反倾的后缘结构面的边坡稳定性研究尚未见到具体讨论。本文采用了数值模拟方法对锦屏一级水电站引渠内侧边坡的稳定性进行了分析,通过结构面参数折减法,求得该边坡稳定性系数为1.191,后端岩体对前端不稳定体不存在推力。通过数值分析方法和极限平衡法对结构面相关参数的敏感性进行了分析对比,对比表明采用参数折减法的数值分析方法结果可靠。本文为类似复杂岩体边坡稳定性判定提供参考。     

新疆博格达山的构造演化及其与油气的关系

博格达山的构造演化及其造山作用的时间是一个长期争议且缺乏系统研究的问题。在野外调查的基础上,充分吸收前人成果,综合运用岩浆岩地球化学特征、不整合-沉积旋回、古流向及沉积物扩散方向等分析手段,对博格达山的构造演化进行了精细的剖析。结果表明:博格达山的构造演化主要经历了3期构造反转,即中-晚石炭世的裂陷海槽与晚石炭世末的弱造山期、早-中二叠世的裂陷盆地与晚二叠世-三叠纪和晚三叠世末的古博格达山隆升-夷平期以及早-中侏罗世的弱伸展盆地与晚侏罗世以来的现今博格达山阶段性隆升期;博格达山南缘柴窝堡凹陷地区印支期形成的NE向构造是油气勘探的有利区带。     

含软弱夹层深部软岩巷道稳定性研究

随着能源开采由浅部向深部发展（>700 m）,深部软岩巷道在高地应力下的变形破坏及其合理加固技术成为影响资源安全开采的重要因素。结合国投新集刘庄矿深部软岩及其软弱结构面的力学特性试验成果,提出软弱夹层的破坏准则及其损伤演化模型,并将其应用于含软弱夹层的深部软岩巷道围岩稳定性分析,研究不同支护方案下的围岩变形特性、破损区以及软弱夹层的离层和破坏情况,提出了合理的加固技术参数。