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1.
The present paper deals with the influence of soil non-linearity, introduced by soil liquefaction, on the soil-foundation–structure interaction phenomena. Numerical simulations are carried out so as to study an improvement method to reduce the liquefaction potential in a sandy soil profile subjected to a shaking. The efficiency of the preloading in both the mitigation of a liquefiable soil and the reduction of induced structure relative settlements is showed. However, the intervention at the foundation soil modifies the dynamic characteristics of soil–structure system and it seems to increase the induced seismic forces during earthquake. In addition, a numerical parametric analysis is performed so as to quantify the impact of the uncertainties associated with the input signal on both the ground motion and the apparition of liquefaction phenomena. 相似文献
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液化规范判别与实际震害现象的差异对比——以唐山地震震害为例 总被引：1，自引：0，他引：1
砂土液化判别是地震地质灾害判定和预测的一项重要工作,判别方法以规范为主,但在实际工作中发现规范的判别结果与实际情况存在差异。本文在查阅大量唐山地震震害资料的基础上,选择3个典型工程场地,根据实际钻孔现场标贯原位测试数据,采用《建筑抗震设计规范》中的方法进行液化判别,发现规范判别结果与实际震害现象之间存在着一些差异。分析认为,抗震设防烈度与实际地震动不同、地下水位变化、上覆非液化土层的厚度、局部场地效应、地震动持时以及实验造成的人为误差等,均是造成差异的原因。分析结果也表明,规范中的判别方法具有较普遍的适用性和较强的实用性,但由于基础数据的局限性及判别公式本身存在的定性异常,其判别结果的合理性还有待于进一步研究论证,这也是造成判别结果与实际震害现象存在差异的原因之一。本文的研究结果对地震液化的机理认识、判别方法的完善,均具有一定的意义。 相似文献
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砂土液化诱发地面侧移分析 总被引：2，自引：0，他引：2
分析了砂土液化诱发地面侧移的机理，提出了估计砂土液化诱发地面侧颓废不久位一种新方法。该方法是用饱和砂层中水压力的发展，在每个应力循环内对土壤的抗剪强度进行修正，然后在每个应力循环内应用Ｎｅｗｍａｒｋ刚性愉模型计算地面侧向永久位移，对比计算表明，本文提出的方法在物理机制上更加合理，计算结果与宏观震害现象十分吻合。 相似文献
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Juliet F. Bird Julian J. Bommer Helen Crowley Rui Pinho 《Soil Dynamics and Earthquake Engineering》2006,26(1):15-30
The assessment of building damage caused by liquefaction-induced ground deformations requires the definition of building capacity and vulnerability as a function of the demand, as well as damage scales to describe the state of the damaged building. This paper presents a framework for resolving these issues within the context of earthquake loss estimations, where large variations in building stock and ground conditions must be considered. The principal modes of building response to both uniform and differential ground movements are discussed and the uncertainties in their evaluation are highlighted. A unified damage scale is proposed for use in both reconnaissance and assessment of all modes of building damage, including ‘rigid body’ response of structures on stiff foundations to uniform or differential ground movements. The interaction of ground shaking and liquefaction in the context of induced structural damage is also briefly considered. The paper raises important aspects of earthquake loss estimations in regions of liquefaction potential, which remain relatively poorly defined at present. 相似文献
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一种新的假说阐述了在大地震中饱和沙土的液化现象。这是建立在多反射理论和FEM动力反应计算的基础上的。计算中应用了在1994年三陆外海M7.5地震时对八户港土层的假设,其结果与观测到的地震现象十分符合。这种方法也被应用于其他曾经发生液化的地区并被证实是在液化机理可接受限度内。富井地震(1948年6月,M=7.1)发生在福井盆地中央,深度为15 km,引起了大范围的破坏,伤亡人数达到5 300人。这次地震在各处引起大面积的液化,导致大范围的稻田被砂石所覆盖。但是,尽管加速度很大,盆地的几部分没有被液化。应用这种假说,我们分析了在相同情况下地表层的差异。结果发现液化的产生取决于地表层刚性引起的应变大小,假设与实际情况一致。 相似文献
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Liquefaction macrophenomena in the great Wenchuan earthquake 总被引：3，自引：2，他引：1
Longwei Chen Xiaoming Yuan Zhenzhong Cao Longqing Hou Rui Sun Lin Dong Weiming Wang Fanchao Meng Hongjuan Chen 《地震工程与工程振动(英文版)》2009,8(2):219-229
On May 12, 2008 at 14:28, a catastrophic magnitude M 8.0 earthquake struck the Sichuan Province of China.The epicenter was located at Wenchuan (31.00°N, 103.40°E). Liquefaction macrophenomena and corresponding destruction was observed throughout a vast area of 500 km long and 200 km wide following the earthquake. This paper illustrates the geographic distribution of the liquefaction and the relationship between liquefaction behavior and seismic intensity, and summarizes the liquefaction macrophenomena, including sandboils and waterspouts, ground subsidence, ground fissures etc., and relevant liquefaction features. A brief summary of the structural damage caused by liquefaction is presented and discussed. Based on comparisons with liquefaction phenomena observed in the 1976 Tangshan and 1975 Haicheng earthquakes, preliminary analyses were performed, which revealed some new features of liquefaction behavior and associated issues arising from this event. The site investigation indicated that the spatial non-uniformity of liquefaction distribution was obvious and most of the liquefied sites were located in regions of seismic intensity Ⅷ. However, liquefaction phenomena at ten different sites in regions of seismic intensity Ⅵ were also observed for the first time in China mainland. Sandboils and waterspouts ranged from centimeters to tens of meters, with most between 1 m to 3 m. Dramatically high water/sand ejections,e.g., more than 10 m, were observed at four different sites. The sand ejections included silty sand, fine sand, medium sand,course sand and gravel, but the ejected sand amount was less than that in the 1976 Tangshan earthquake. Possible liquefaction of natural gravel soils was observed for the first time in China mainland. 相似文献
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地下管道的震害预测方法简述 总被引：1，自引：0，他引：1
强烈的地面运动或场地失效等因素是造成地震中地下管道破坏的主要因素。本文对地震波作用下和砂土液化条件下管道的震害预测方法进行了概述,并基于综合概率法对埋地管道进行了分析预测。 相似文献
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The 1995 Hyogoken–Nambu earthquake caused severe liquefaction over wide areas of reclaimed land. Furthermore, the liquefaction induced large ground displacement in horizontal directions, which caused serious damage to foundations of structures. However, few analyses of steel pipe piles based on field investigation have so far been conducted to identify the causes and process of such damage. The authors conducted a soil–pile-structure interaction analysis by applying a multi-lumped-mass-spring model to a steel pipe pile foundation structure to evaluate the causes and process of its damage. The damage process analyzed in the time domain corresponded well with the results of detailed field investigation. It was found that a large bending moment beyond the ultimate plastic moment of the pile foundation structure was induced mainly by the large ground displacement caused by liquefaction before lateral spreading of the ground and that the displacement appeared during the accumulating process of the excess pore water pressure. 相似文献
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Assessment of liquefaction-inducing peak ground velocity and frequency of horizontal ground shaking at onset of phenomenon 总被引：1，自引：0，他引：1
It is recognized that soil improvement techniques are not economically feasible for mitigation of liquefaction-induced lifeline damages because of the large areas served. Instead, it is more practical to execute an emergency action immediately after an earthquake in order to prevent or minimize possible lifeline failures caused by the soil liquefaction. Essential element in the implementation of such a plan is the real-time identification of liquefied sites, which can be successfully achieved by analyzing surface strong motion records. In this paper, the thresholds of two ground motion parameters—the peak surface velocity and horizontal shaking frequency of the ground—that are associated with the soil liquefaction are assessed utilizing the theory of one-dimensional wave propagation in linearly elastic medium. Obtained simple expressions for both parameters are used to estimate their ranges and are examined against several case histories. Minimum level of peak ground velocity (PGV) is verified by experimental data from shaking-table test. Linear relationships between amplitude ground motion parameters at liquefied-soil sites are also developed. Results suggest that liquefaction is likely to take place when PGV exceeds 0.10 m/s and that the upper bound of horizontal ground vibration frequency after liquefaction occurrence is 1.3–2.3 Hz. 相似文献
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GEOLOGICAL HAZARD CHARACTERISTICS AND MACROSCOPIC EPICENTER OF NOVEMBER 25, 2016, ARKETAO,XINJIANG, MW6.6 EARTHQUAKE 
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下载免费PDF全文 The MW6.6 Arketao earthquake occurred on November 25, 2016 in Muji Basin of the Kongur extensional system in the eastern Pamir. The region is the Pamir tectonic knot, one of the two structural knots where the India plate collides with the Eurasian plate. This region is one of the most active areas in mainland China. The seismogenic structure of the earthquake is preliminarily determined as the Muji dextral-slip fault which locates in the north of Kongur extensional system. Based on field surveys of seismic geological hazard, and combined with the characteristics of high altitude area and the focal mechanism solution, this paper summarizes the associated distribution and development characteristics of sandy soil liquefaction, ground fissures, collapse, and landslide. There are 2 macroscopic epicenters of the earthquake, that is, Weirima village and Bulake village. There are a lot of geological hazards distributed in the macroscopic epicenters. Sand liquefaction is mainly distributed in the south of Kalaarte River, and area of sand liquefaction is 1 000m2. The liquefaction material gushed along the mouth of springs and ground fissures, because of the frozen soil below the surface. More than 60% of soil liquefactions are formed in the mouth of springs. According to the trenching, these liquefactions occurred in 1.8 meters underground in the gray green silty clay and silty sand layers. The ground fissures are mainly caused by brittle failure, and the deformation of upper frozen soil layer is caused by the deformation of lower soil layer. The ground fissures at Weirima village are distributed in a chessboard-like pattern in the flood plain of Kalaarte River. In the Bulake village, the main movement features of the ground fissure are tension and sinistral slip, and the directions of ground fissures are 90°~135°. The collapse and landslide are one of the important geological disasters in the disaster area. The rolling stones falling in landslide blocked the roads and smashed the wire rods, and the biggest rolling stone is 4 meters in length. We only found a small landslide in the earthquake area, but there are a large number of unstable slopes and potential landslides in the surroundings. The ground fissures associated with sand liquefaction are an important cause of serious damage to the buildings. 相似文献
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近岸水平场地液化侧向大变形机理及软化模量分析方法 总被引：3，自引：1，他引：3
本文依据震害现象和实验探讨近岸水平场地地面液化侧向大变形机理，改进现有软化模量分析技术，给出一套地面液化侧向大变形的分析方法。近岸水平场地侧向大变形机理因地基中孔隙水压力升高、土体模量衰减、土骨架变软使偏应变得到充分发展所致，其水平永久侧移可用从底部到顶部呈增加形式的整体变形描述。利用本文方法，对1995年阪神地震中近岸沉箱岸壁和土体液化侧向大变形进行了数值模拟，结果与震后实测结果和试验结果在主要特征上一致，说明改进的软化模量法可以用于地面液化侧向大变形的分析。 相似文献
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The building losses in Adapazari following the 17 August 1999 Kocaeli earthquake are estimated for both ground-shaking and ground-failure induced damage and the predictions compared with field observations. The ground-shaking damage is estimated using the capacity spectrum approach and accommodating the results of a previously published calibration of this model. These results, which do not incorporate ground-failure damage, are compared to the observed damage patterns in Adapazari to illustrate the significance of not including the more complex ground failure component in a loss model for a region of high liquefaction susceptibility. A preliminary estimation of ground-failure-induced damage is then presented based upon the HAZUS (FEMA, 2003) default methodology. The benefits of these additional calculations to the overall loss model are assessed to provide some quantitative decision-making guidance for those producing loss estimation models. The findings suggest that the benefits of specifically incorporating ground failure into a loss model only start to be obtained if a detailed approach using in situ geotechnical data as well as adequate representation of building foundations is adopted. Otherwise, the additional input data required is not commensurate with the small potential refinement in the estimated losses, particularly considering the compounded uncertainties associated with the simplified approach. 相似文献
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During the 1999 Chi-Chi, Taiwan earthquake, many sand boiling phenomena were observed in central Taiwan, which caused severe ground settlement and structure damages. According to the installed accelerograms, the peak ground surface horizontal accelerations in the liquefaction-affected areas range from 774.42 to 121.3 gal. The writers carried out an extensive investigation of soil liquefaction in this earthquake. In this paper, we present results of the CPT exploration and post-earthquake liquefaction analysis. Two hundred and seventy five (275) cone penetration test data were collected from the liquefaction-affected areas, and 46 liquefaction case histories and 88 non-liquefaction case histories were derived that can be used to evaluate the accuracy of existing liquefaction evaluation models. In addition, the strength of the liquefied soils after earthquake and the implication of its liquefaction potential in the future event are discussed. 相似文献
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The Barrow-in-Furness Earthquake of 15 February 1865: Liquefaction from a Very Small Magnitude Event 总被引：1，自引：0，他引：1
R. M. W. Musson 《Pure and Applied Geophysics》1998,152(4):733-745
—High intensity and liquefaction phenomena are usually associated only with relatively large magnitude earthquakes. An earthquake in 1865 in the northwest of England suggests that a sufficiently shallow small event can also produce liquefaction. The effects are well-documented in historical sources and include sand fountaining. Modern investigation is confined to documentary evidence owing to the tidal environment of the area where liquefaction occurred. Analysis shows that the felt area of the earthquake was probably only about 200 km2; however, heavy damage occurred in the village of Rampside and the maximum intensity is assessed at 8. Liquefaction is not uncommon at this intensity, but such a high intensity is not usually produced by such small erathquakes. The magnitude was probably in the range 2.5–3.5 M L . 相似文献
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The Canterbury region experienced widespread damage due to liquefaction induced by seismic shaking during the 4 September 2010 earthquake and the large aftershocks that followed, notably those that occurred on 22 February, 13 June and 23 December 2011. Following the 2010 earthquake, the Earthquake Commission directed a thorough investigation of the ground profile in Christchurch, and to date, more than 7500 cone penetration tests (CPT) have been performed in the region. This paper presents the results of analyses which use a subset of the geotechnical database to evaluate the liquefaction process as well as the re-liquefaction that occurred following some of the major events in Christchurch. First, the applicability of existing CPT-based methods for evaluating liquefaction potential of Christchurch soils was investigated using three methods currently available. Next, the results of liquefaction potential evaluation were compared with the severity of observed damage, categorised in terms of the land damage grade developed from Tonkin & Taylor property inspections as well as from observed severity of liquefaction from aerial photography. For this purpose, the Liquefaction Potential Index (LPI) was used to represent the damage potential at each site. In addition, a comparison of the CPT-based strength profiles obtained before each of the major aftershocks was performed. The results suggest that the analysis of spatial and temporal variations of strength profiles gives a clear indication of the resulting liquefaction and re-liquefaction observed in Christchurch. The comparison of a limited number of CPT strength profiles before and after the earthquakes seems to indicate that no noticeable strengthening has occurred in Christchurch, making the area vulnerable to liquefaction induced land damage in future large-scale earthquakes. 相似文献
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Geotechnical evaluation of slope and ground failures during the 8 October 2005 Muzaffarabad earthquake, Pakistan 总被引：4，自引：0，他引：4
A large devastating earthquake with a magnitude of 7.6 struck in Kashmir on Oct. 8, 2005. The largest city influenced by the
earthquake was Muzaffarabad. Balakot town was the nearest settlement to the epicenter, and it was the most heavily damaged.
The earthquake caused extensive damage to housing and structures founded on loose deposits or weathered/sheared rock masses.
Furthermore, extensive slope failures occurred along Neelum and Jhelum valleys, which obstructed both river flow and roadways.
In this article, failures of natural and cut slopes as well as other ground failures induced by the earthquake and their geotechnical
evaluation are presented, and their implications on civil infrastructures and site selection for reconstruction and rehabilitation
are discussed. It is suggested that if housing and constructions on soil slopes containing boulders as observed in Balakot
and Muzaffarabad are allowed, there should be a safety zone between the slope crest and allowable construction boundary. 相似文献
18.
本文着重研究了近代工程施工中发现的大量震害遗迹, 诸如断层、裂缝、喷水冒砂现象, 诱发滑坡和坠入地震断裂带中的木炭与文物.又经考古研究和 C14鉴定属明代之物, 证实这条在极震区延伸大于70公里的破裂带就是这次大地震极震区地面破裂带. 相似文献
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为研究倾斜场地中桩基的动力响应,以2011年新西兰地震中受损的Dallington桥为原型,设计并完成可液化倾斜场地桥梁桩-土相互作用的振动台模型试验。试验再现了喷砂、冒水、地裂缝、场地流滑等宏观现象。试验结果表明,土层足够的液化势及惯性是造成倾斜场地侧向流滑的必要条件;浅层土相比深层土更易液化,液化层中的加速度由下至上呈现逐渐衰减的趋势,而未液化砂土层却表现为逐渐增大的特征;深部测点的桩侧土压力明显大于浅部测点,且土体的液化会弱化土对结构的压力;结构应变最大值位于上部桥台,而结构弯矩在桩身中部及土层分界面附近出现两个较大值,桩端嵌固及倾斜场地流滑是造成出现两个弯矩较大值的主要原因。 相似文献
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桥台在桥梁系统中占据重要位置,桥台的稳定性直接影响到桥梁的抗震性能。在国内外大量震害中发现大量由桥台破坏引起的桥梁损坏,而且这些破坏常常伴随着由于液化引起的地面大变形。为研究液化场地中桥台滑坡机理,采用完全耦合的有效应力分析方法,利用修正的PasterZienkiewicz Mark-Ⅲ模型来模拟砂土在地震荷载作用下的液化特性。研究台顶梁重和液化层位置对桥台位移的影响,并分析夯实作用对砂土液化的影响。结果表明:模拟得出结果与振动台试验结果基本一致,而且简单的夯实不能降低砂土液化的风险。 相似文献