应力扰动对地震周期和地震矩影响的数值模拟          下载免费PDF全文

翁辉辉  黄金水 《地震学报》2015,37(1):65-79

利用二维有限元数值模型,结合断层滑移弱化摩擦准则对断层滑动规律以及应力扰动对其影响进行了研究．数值计算结果表明,在均匀应力分布情况下, 平面断层滑动显示出典型的特征地震规律,断层面上的应力扰动对断层滑动规律产生影响,压应力增加明显延迟地震的发生时间,并增加地震释放的能量．应力扰动发生在地震破裂临界区时的影响比在震前滑移区时的影响显著．当发生在地震滑移区时,若应力扰动足够大,则压应力增大会造成地震发生时部分动力断层被暂时锁住,使得地震释放的能量变小,但可增加后续地震的能量; 而压应力减小则可导致地震规律产生更加复杂的变化,会即时触发地震．如果应力扰动发生在一个地震周期的早期,则触发的地震较小,但可导致随后的地震提前发生; 如果应力扰动发生在一个地震周期的后期,则会触发大地震．当应力扰动位于震前滑移区或破裂临界区时,小的扰动也可能产生类似的效果．应力扰动产生越晚,这种影响也越明显．应力扰动发生在破裂临界区的影响最明显．应力扰动的影响一般主要集中在应力发生扰动后的1—2个地震周期内．后续地震基本恢复无应力扰动时的特征地震规律．   相似文献   

微量元素在湖积物、土壤的垂向分布与稻谷中的分配   总被引：22，自引：7，他引：15       下载免费PDF全文

廖启林  黄顺生  范迪富  吴新民  朱伯万  翁志华  华明  陈宝  冯金顺 《第四纪研究》2005,25(3):331-339

报道了“江苏省国土生态地球化学调查”项目有关湖积物、土壤柱微量元素垂向分布及稻谷样元素分配研究的初步成果。通过对有关样品元素含量的分析对比,指出洪泽湖沉积柱元素垂向分布与其动荡的沉积环境关系密切、太湖局部沉积物在其目前20cm以上深度存在人为重金属污染,这二湖沉积物中其氮与总有机碳含量呈显著正相关;认为城市化可使当地土壤环境受重金属等污染的深度显著加大、城市土壤环境受人为活动的影响要显著高于农村;发现Mo易富集于稻米、重金属与营养元素易富集于稻皮、各元素在米-谷间的分配关系不确定。  相似文献   

Self‐centering structural systems with combination of hysteretic and viscous energy dissipations     

Weng Yuen Kam  Stefano Pampanin  Alessandro Palermo  Athol J. Carr 《地震工程与结构动力学》2010,39(10):1083-1108

This paper presents an innovative set of high‐seismic‐resistant structural systems termed Advanced Flag‐Shaped (AFS) systems, where self‐centering elements are used with combinations of various alternative energy dissipation elements (hysteretic, viscous or visco‐elasto‐plastic) in series and/or in parallel. AFS systems is developed using the rationale of combining velocity‐dependent with displacement‐dependent energy dissipation for self‐centering systems, particularly to counteract near‐fault earthquakes. Non‐linear time‐history analyses (NLTHA) on a set of four single‐degree‐of‐freedom (SDOF) systems under a suite of 20 far‐field and 20 near‐fault ground motions are used to compare the seismic performance of AFS systems with the conventional systems. It is shown that AFS systems with a combination in parallel of hysteretic and viscous energy dissipations achieved greater performance in terms of the three performance indices. Furthermore, the use of friction slip in series of viscous energy dissipation is shown to limit the peak response acceleration and induced base‐shear. An extensive parametric analysis is carried out to investigate the influence of two design parameters, λ₁ and λ₂ on the response of SDOF AFS systems with initial periods ranging from 0.2 to 3.0 s and with various strength levels when subjected to far‐field and near‐fault earthquakes. For the design of self‐centering systems with combined hysteretic and viscous energy dissipation (AFS) systems, λ₁ is recommended to be in the range of 0.8–1.6 while λ₂ to be between 0.25 and 0.75 to ensure sufficient self‐centering and energy dissipation capacities, respectively. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

信江盆地丹霞地貌特征及其景观类型   总被引：3，自引：0，他引：3  

姜勇彪  郭福生  胡中华  刘林清  吴志春 《山地学报》2010,28(4)

信江盆地是我国丹霞地貌发育典型代表区域之一.通过对该盆地红层分布区遥感影像解译,并结合野外调查分析,总结出丹霞地貌遥感影像具有网格状、脑状、栅栏状、斑点状、斑块状和圆丘状6种影纹特征,表征不同的丹霞地貌景观类型,并在盆地内圈划出15个丹霞地貌集中分布区.野外调查识别出信江盆地丹霞地貌共8大类23种单体景观类型、4种组合类型.其在盆地内分布呈一定的规律性变化:盆地边缘,遥感影像成网格状的,网格的密度较大,以顶斜的峰林、峰从景观组合为特征,其演化处于壮年末期至老年早期阶段;盆地中央沿河流两岸,遥感影像上呈现大片红色,以圆丘状低矮的小石峰为特征,山顶植被稀少,岩石裸露,地貌演化处于幼年至青年阶段;中间过渡地带一般丹霞地貌不发育或成圆丘型丹霞地貌组合,只在少数地区由于发育断层或有信江支流流经之处发育,也以石寨、巷谷(一线天)岩崖等景观为特征,遥感影像上呈现条块状,崖壁延升较远,嶂谷发育,反映其发育处于青年晚期至壮年早期阶段.  相似文献   

Preliminary investigation of seismic damage to two steel space structures during the 2013 Lushan earthquake   总被引：2，自引：2，他引：0  

Dai Junwu  Qu Zhe  Zhang Chenxiao  Weng Xuran 《地震工程与工程振动(英文版)》2013,12(3):497-500

Severe damage to steel space structures is rarely reported when compared to other structural systems damaged during past major earthquakes around the world.Two gymnasiums of steel space structures in downtown Lushan County that were damaged during the 2013 M7.0 Lushan earthquake in China were investigated and the observations are summarized in this paper.Typical damage to these two steel space structures ranges from moderate to severe.Moderate damage includes global buckling and dislocation of bolted connections of truss members,and inelastic elongation of anchor bolts and sliding of pedestal plates of supports.Severe damage includes member fracture caused by local buckling,and fracture failure of anchor bolts and welds.The distribution of structural damage to these two structures is described in detail and future research opportunities are suggested.  相似文献   

Earthquake response analyses of a full‐scale five‐story steel frame equipped with two types of dampers     

Yi‐Jer Yu  Keh‐Chyuan Tsai  Chao‐Hsien Li  Yuan‐Tao Weng  Ching‐Yi Tsai 《地震工程与结构动力学》2013,42(9):1301-1320

The seismic performance tests of a full‐scale five‐story passively controlled steel building were conducted on the E‐Defense shaking table in Japan in March 2009. Before the tests, a blind prediction contest was held to allow researchers and practitioners from all over the world to construct analytical models and predict the dynamic responses of the steel frame specimen equipped with buckling‐restrained braces (BRBs) or viscous dampers (VDs). This paper presents the details of two refined prediction models made and results obtained before the tests. When the proposed analytical modeling techniques are adopted as in the two refined prediction models, the overall prediction accuracy is about 90%. Sensitivity studies conducted after the tests are also presented in this paper. The effects of varying each modeling feature on the response simulation accuracy have been investigated. The analytical results suggest that considering concrete full‐composite actions for beam members could improve prediction accuracy by about 20% against using the simplified bare steel beam model. Adopting refined BRB stiffness computed from incorporating finite‐element gusset stiffness only improves the overall prediction accuracy by 0.9%. Considering the BRB dynamic loading test results for analytical BRB strength reduces the error by 1.9%. For the VD frame, incorporating the brace and VD stiffness could improve the overall prediction accuracy by about 15%. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

A PRIMARY RECOGNITION ON THE CLIMATIC SIGNIFICANCE OF ICE CORE ISOTOPE RECORD IN NAIMONA'NYI OF WEST TIBETAN PLATEAU     

Tian Lide  Yao Tandong  Wen Rong  Weng Yongbiao  Zhao Zhongping  Qu Dongmei 《第四纪研究》2012,32(1)

纳木那尼冰川是喜马拉雅山西部地区规模较大的冰川之一,也是开展冰芯气候意义研究有重要潜在价值的冰川.但由于纳木那尼冰川位于西风环流和印度季风影响范围的交界带,不同的环流系统所输送的水汽带来不同的降水稳定同位素信号.因此确定纳木那尼冰芯同位素记录的气候意义是开展该地区冰芯气候记录研究的前提条件.2008年在该冰川积累区所钻取的8.78m浅冰芯为这一研究工作提供了可能.本文对该冰芯的稳定同位素记录以及普兰气象站的气象数据进行了分析与讨论.研究结果表明,同位素的年际变化与当地普兰县气象站气温的年际变化具有较好的对应关系.这可能与当地降水受到夏季季风的影响较小有关.测量结果表明早期的深冰芯钻取点位于冰川的消融区,而冰川的积累区仍位于冰川更高的区域,而且积累区冰川厚度更大,更有可能保存更长时间尺度的冰芯记录.这也为以后开展新的纳木那尼深孔冰芯及气候意义研究提供了借鉴.  相似文献   

The contribution of organic and mineral colloidal nanoparticles to element transport in a podzol soil     

Inge C. Regelink  Liping Weng  Willem H. van Riemsdijk 《Applied Geochemistry》2011

The aim of this work is to analyze the size-distribution and composition of nanoparticles in a water-extract of a podzol B horizon. AsFlowFFF coupled to ICP–MS and a UV/VIS detector was used for particle fractionation and simultaneous measurement of the composition of the nanoparticles. Detected nanoparticles were organic and mineral particles; the mineral particles were dominated by clay and Fe-(hydr)oxides. Both organic- and inorganic particles contributed to the mobility of Fe, Al, trace metals and P. For Zn, Pb and P respectively 73%, 92% and 72% of the colloidal concentrations were associated with clay minerals. The large contribution of clay particles to the mobility of trace metals and P can be partly explained by the high amount of dispersed clay due to drying, sieving and rewetting of the soil. Inorganic nanoparticles can contribute significantly to the mobility of metals and P in soils.  相似文献   

江西信江盆地丹霞地貌形成机制分析   总被引：1，自引：1，他引：0  

姜勇彪  郭福生  刘林清  胡中华  吴志春  吴智勇 《热带地理》2011,31(2)

信江盆地是我国丹霞地貌发育最典型的区域之一。由于影响丹霞地貌演化的成景系统诸要素具有不同特征,信江盆地内不同部位丹霞地貌经历了不同的演化进程,不同发育阶段的丹霞地貌在盆地内成带状分布。盆地边缘由于受红层岩性、断裂构造及信江支流等因素影响,地表剥蚀速率快,丹霞地貌演化已步入壮年晚期至老年早期阶段,以丹霞石林、峰林、峰丛、崖壁以及各种类型的造型石为特征;盆地中部虽然断裂构造发育程度较弱,但受信江流水侵蚀,丹霞地貌演化也步入青年期至壮年早期阶段,以低矮的圆丘状丹霞石峰及岩洞为特征;而中部过渡地带,由于构造、水系发育均较弱,地貌演化速率慢,丹霞地貌演化处于幼年期至青年早期阶段,以石寨、巷谷、岩崖等景观为特征。  相似文献   

Numerical Modeling of Hydraulic Fractures Interaction in Complex Naturally Fractured Formations   总被引：1，自引：0，他引：1  

Olga Kresse  Xiaowei Weng  Hongren Gu  Ruiting Wu 《Rock Mechanics and Rock Engineering》2013,46(3):555-568

A recently developed unconventional fracture model (UFM) is able to simulate complex fracture network propagation in a formation with pre-existing natural fractures. A method for computing the stress shadow from fracture branches in a complex hydraulic fracture network (HFN) based on an enhanced 2D displacement discontinuity method with correction for finite fracture height is implemented in UFM and is presented in detail including approach validation and examples. The influence of stress shadow effect from the HFN generated at previous treatment stage on the HFN propagation and shape at new stage is also discussed.  相似文献