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1.
Shaking table tests and numerical simulation of dynamic properties of underground structures 
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下载免费PDF全文 It is considered that the damage of the underground structures caused by earthquakes is minor for a long time. However, the catastrophic damages induced by several recent earthquakes ( e. g. Kobe earthquake in 1995) revealed that the study on the dynamic properties of the underground structures is indispensable. The dynamic behavior and damage mechanism of underground structure are analyzed by using shaking table tests ( both shallow- and deep-buried) and numerical simulation ( 3D FEM) including horizontal and vertical input motions, individually and simultaneously. From the results, the underground structure collapsed due to strong horizontal forces although vertical deformation is not negligible. The vertical excitation increases the response of structure, especially the stress and shear stress at the upper section; the soil influenced the property of soil-structure system. In the same excitation, the response in shallow-buried test is larger than deep case. Both overburden and vertical earthquake play important roles in the response of structure and those are two critical aspects in the design of the large-span underground structures, such as subway stations. 相似文献
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《山地科学学报》2021,(4)
In an earlier study of the Diexi ancient dammed lake along the Minjiang River in Southwest China, 10 disturbed layers with envelope and flame structures were found in more than 240 m of lacustrine sediments. In this paper, the soft-sediment disturbances caused by earthquakes in the Diexi ancient dammed lake were studied based on field investigations and laboratory core observations. A two-to three-degree-of-freedom spring-type earthquake simulation vibration table was used to carry out disturbance tests on lacustrine sediments under different dynamic conditions. The results support the following conclusions:(1) The disturbance layers in the lacustrine sediments were caused by strong earthquakes in the region.(2) The characteristics of the disturbance layers are related to the seismic parameters and the degree of sediment consolidation.(3) The greater the earthquake intensity is, the greater the disturbance amplitude is; moreover, the lower the consolidation degree is, the greater the disturbance amplitude.(4) The simulation tests verify that the disturbance layers in the sediments of the Diexi ancient dammed lake correspond to strong earthquakes in the region. These results are valuable for ongoing palaeoseismic research in the region. 相似文献
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对１９９６年丽江７．０级和１９７６年唐山７．８级地震前的形变场动态演化过程做了对比分析，结果表明：①两次强震前形变场均存在大范围垂直差异运动增强以及与构造相关的形变高梯度带（区）；②震前数年（或更长）垂直形变场的趋势改变，并出现形变局部化。结合强震前区域地震活动，研究了这两次地震前垂直形变场动态演化与孕震形变的异常特征，认为与构造相关的强烈差异运动是孕震应变能积累的主要方式。 相似文献
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运用非连续变形分析（DDA）和有限元方法(FEM)对砌体结构进行震动分析。建模中将砌体结构的砖、柱、过梁以及楼板等视为独立的弹性体分别作有限元划分,弹性体之间运动由接触界面的张开、闭合和滑动控制来实现,通过防止弹性体间的侵入来校正弹性块体系统的位移与应变最小二乘拟合结果。弹性块体间滑动采用库仑摩尔定律控制砂浆的作用与失效,输入相当于地震烈度Ⅸ度的加速度峰值的迁安波对砌体结构模型进行震力分析,研究相应震动过程。算例表明,DDA和FEM组合的方法能很好地模拟砌体结构受地震作用的动力响应过程。在较大地震作用下,砌体结构首先从底层开始开裂破坏并导致结构倒塌,与农村砌体结构震害现象吻合较好。 相似文献
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Based on dynamic response signals a damage detection algorithm is developed for marine risers. Damage detection methods based on numerous modal properties have encountered issues in the researches in offshore oil community. For example, significant increase in structure mass due to marine plant/animal growth and changes in modal properties by equipment noise are not the result of damage for riser structures. In an attempt to eliminate the need to determine modal parameters, a data-based method is developed. The implementation of the method requires that vibration data are first standardized to remove the influence of different loading conditions and the autoregressive moving average (ARMA) model is used to fit vibration response signals. In addition, a damage feature factor is introduced based on the autoregressive (AR) parameters. After that, the Euclidean distance between ARMA models is subtracted as a damage indicator for damage detection and localization and a top tensioned riser simulation model with different damage scenarios is analyzed using the proposed method with dynamic acceleration responses of a marine riser as sensor data. Finally, the influence of measured noise is analyzed. According to the damage localization results, the proposed method provides accurate damage locations of risers and is robust to overcome noise effect. 相似文献
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为定量研究地表与井下背景噪声的异同,在同一台站地表架设地震计,与井下地震计进行同步观测。首先选取样本数据计算背景噪声功率谱密度,分析不同类型地震计安装在不同深度时功率谱密度及平均噪声RMS值的变化特征。通过对比分析3种地震计记录的近震和远震波形发现,地表宽频带、短周期和井下短周期地震计记录的近震波形都比较清晰,震相易于识别,且地表宽频带与井下短周期地震计记录的远震波形更清晰;而地表短周期地震记录的远震波形较差,失真严重,震相不易识别。在进行震源频谱对比分析中发现,相对于地表地震计,井下地震计记录的近震波形在7~12 Hz频段受干扰较为严重,远震波形则在4~7 Hz频段受干扰严重,震相分析时需慎重处理。 相似文献
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采用固定台站的宽频带数字地震波形资料,计算2017-06-16巴东MS4.3地震序列16个ML1.8以上地震的视应力、拐角频率及震源破裂半径等震源参数,并系统分析地震视应力值与各参数之间的关系。结果表明,地震序列视应力值与震级正相关,地震震源谱的高频成分不丰富,拐角频率和视应力值均远小于非水库区的构造地震,震源区地下结构较为复杂。 相似文献
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Zhe Ren Kun Wang Qi-shu Zhang Ze-min Xu Zheng-guang Tang Ji-pu Chen Ji-qing Yang Zong-heng Xu 《山地科学学报》2018,15(1):82-99
Tailings impoundments can potentially collapse due to damage caused by earthquakes, which has frequently occurred around the world. This study takes the proposed valley type tailings impoundment in Yunnan as the research object to analyze the dynamic response behavior under earthquake action with both numerical simulation and physical model test (1:300). The results of both tests show that the dynamic response of the valley type tailings impoundment is characterized by “medium stiffness effect”, in other words, in a certain range, the “softer” the unsaturated tailings sand is, the more energy it can dissipate, which leads the decrease of the value of the acceleration amplification factor. In addition, the peak acceleration of the monitoring points increases with the vertical elevation, which indicates that the “elevation amplification effect” exists in the tailings impoundment dynamic response. The middle part of the outer side of the raised embankment reacts more sensitive than the crest, which is similar to the slope dynamic response. The starter dam reacts sensitively under the earthquake excitation, which should be given more attention during the seismic design. The dynamic response rules reflected by the numerical simulation are consistent with the results monitored on the physical model test, although there are some differences between their values. The dynamic response rules of the valley type tailings impoundment can provide basis for the design of the similar projects in this region. 相似文献
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Some unfavorable geological conditions can affect the construction of tunnels.In order to evaluate the damage degree of tunnel construction and determine the surrounding rock grade and stability of the tunnel,the authors used high-density resistivity method to detect the surrounding rocks of Shimodong tunnel in Xicheng Town of Helong City.The underground resistivity structures of the entrance,exit and middle parts of the tunnel are obtained.Through analysis,it is found that there are no bedrock faults near the tunnel,although some joints and fissures are developed in some locations,which are characterized by low-resistivity anomalies.The tunnel structures are stable overall,favorable for safe and efficient construction.The study also proves the good application effect of the high-density resistivity method in tunnel safety detection. 相似文献
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研究了泾阳5.2级地震前的地壳形变、地下水化学参数、地震分布图象和地震波速比的变化特征,结果表明,在震前该区地壳形变、地下流体和地震活动表现出长期、中期和短期的不同特征,具有一定的前兆异常,作出地震预测是可能的。 相似文献
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利用2010~2016年东北地区的流动重力观测数据,分析该地区区域重力场动态演化和2013年前郭5.8级震群前后的变化特征。结果表明,差分和累积重力变化整体呈北西向和近南北向,与北东和北北东向构造格局不一致,重力变化受构造控制作用较弱;近期整体重力变化较平缓,基本没有超过60 μGal的梯级带,反映出地下构造活动和物质运移水平相对平稳;前郭5.8级震群和通辽5.3级地震震前存在明显的能量积累,有利于破裂的产生,震后震荡恢复调整的时间需2~3 a甚至更长。 相似文献
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为研究强震作用下斜坡表面的动力放大效应, 以陕西勉县某岩质斜坡为例, 建立了三维模型。运用离散元软件3DEC, 模拟了动力条件下斜坡的变形失稳过程, 分析了斜坡表面的动力响应特征, 研究了不同地震波输入工况条件下坡体表面动力响应差异。研究结果表明: 考虑地震纵波的影响时, 竖向加速度得到显著增强, 坡面的PGA放大系数增强了约1.62倍; 坡面形态强烈影响着斜坡表面的动力响应特征, 强震作用下, 斜坡坡肩及坡形转折处的放大效应均十分强烈, 凸出部位次之, 坡表两侧的放大效应最弱; 不同输入工况下, 斜坡坡形转折处的水平向PGA放大系数均维持较高值, 特别是在仅输入水平向加速度的条件下, 该部位在地震滑坡灾害预防中应特别注意; 强震作用下滑坡的运动过程可概括为滑坡孕育启动阶段—挤压碰撞高速运动阶段—堆积阶段。研究成果可为该地区防灾减灾工作提供一定理论支持。 相似文献
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为研究山西南部平陆地区黄河北岸一级阶地中软沉积物变形构造的触发机制,对观测剖面中发育的碟状构造、液化卷曲构造和球枕构造等3类软沉积物变形构造的特征进行描述,分析其形成机制,通过总结对比软沉积物变形的地震成因,推测剖面中的变形构造为地震成因,并依此建立山西南部平陆地区的地震成因地层沉积序列。光释光测年结果显示,该变形构造形成年龄为1.9±0.2 ka,通过影响烈度的计算并结合山西及邻近省的地震资料发现,2次历史地震可能与该软沉积物变形构造相关。 相似文献
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1 IntroductionAccordingtogeologicalstructure ,theGansu Ningxia Qinghaiareabelongstothenortheastmar ginofQinghai Tibetblock .Thisareahasbeenpaidmuchattentionby geo specialistsinChinaandabroadbecauseofitssignificanttectonicmovement,itsintensiveseismicity ,anditsimportanceinearth quakehazardmitigation .IntheDevelopmentPro gramonNationalKeyBasicResearchesundertheProject“MechanismandPredictionofContinentalStrongEarthquakes”,themechanismsofcontinen talstrongearthquakesarestudied ,usinghypo… 相似文献
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济宁城区地面沉降演变规律及经济损失估算方法 总被引：1，自引：0，他引：1
济宁城区位于汶泗河冲积平原的前缘地带，孔隙地下水资源丰富，开采量多年来处于超采状态，1988年以来发生了地面沉降。经采取调整地下水开采井布局等措施后，城区地面沉降速率逐渐减小，而沉降漏斗随地下水的开采向城区北部、东北部转移，地面沉降值大于60mm的范围达到了145km^2证实地面沉降的发生完全受控制于地下水的开采程度。根据济宁市地面沉降的危害程度和破坏性，可将其造成的经济损失分为直接和间接经济损失，其中间接经济损失为全部经济损失的75％以上。 相似文献
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鄂尔多斯地块的动力背景是青藏高原东北缘NE向推挤作用的结果。1970年以来,鄂尔多斯地块北缘现今地震活动表明,中强地震活动具有幕式活动特征,从1970~2015年共经历了4幕活动;块体西北缘与东北缘的中强地震具有迁移对跳活动特征,1970年以来共经历了4组对跳;震例统计结果揭示,地块北缘6.0级左右地震前,块体中等地震经历长时间平静具有普适特征;2005-03以来,块体所在的阴山地震带再次进入中等地震超长平静时段。其幕式活动特征、迁移特征、时间平静特征可作为区域范围强震的预测指标。 相似文献
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德州市深层地下水,由于长期大量开采,早已形成降落漏斗。作者从漏斗条件的实际出发,利用１７年的地下水动态观测资料,在地下水资源均衡基础上,进行相关分析,建立了相关模型。利用相关模型直接进行不同开采条件下的地下水位预报和限定地下水位条件下的开采量计算。此外,还利用相关模型进行了含水层（组）弹性释水系数和漏斗补给量计算。 相似文献
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为研究重力时变因素对流动重力网数据处理结果的影响,利用动态和静态2种平差方法对南北地震带南段流动重力观测数据进行处理,并对2种方法的重力变化结果进行对比分析。结果表明：1）重力时变因素会导致静态平差方法计算的重力变化结果存在误差,对0.5 a和1 a时间尺度下的重力变化具有较为明显的影响,但对2 a以上时间尺度下的重力变化影响较小,因此计算0.5 a和1 a时间尺度下的重力变化时宜采用动态平差方法;2）研究区内九寨沟7.0级、长宁6.0级和漾濞6.4级地震的发震地点与重力变化零值线具有较好的对应关系,重力变化图像可反映3次地震的发震背景。 相似文献
19.
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基于2016年以来雷州半岛-海南岛陆地区（以下简称雷琼地区）的流动重力资料,对2017年下半年前后的联测资料采用不同的平差方法进行处理。将湛江和琼中2个绝对重力点作为雷琼测网基准,研究2016年以来雷琼地区重力场动态变化特征。重点研究2018-03-20广东阳江4.2级地震、2019-03-05广东雷州4.1级地震、2019-08-20海南三亚4.2级地震和2019-10-12广西北流5.2级地震震前区域重力场差分和累积动态变化。研究结果表明,除广东雷州4.1级地震外,其他3个地震震前在震中附近地区均存在重力场变化异常,表明在测网网格距和数据处理方法合理的情况下,对于4~5级地震,区域重力场在震前可能存在一定异常反应。 相似文献