Analysis of buried pipelines subjected to reverse fault motion

Presently available simplified analytical methods and semi-empirical methods for the analysis of buried pipelines subjected to fault motion are suitable only for the strike-slip and the normal-slip type fault motions, and cannot be used for the reverse fault crossing case. A simple finite element model, which uses beam elements for the pipeline and discrete nonlinear springs for the soil, has been proposed to analyse buried pipeline subjected to reverse fault motion. The material nonlinearities associated with pipe-material and soil, and geometric nonlinearity associated with large deformations were incorporated in the analysis. Complex reverse fault motion was simulated using suitable constraints between pipe-nodes and ground ends of the soil spring. Results of the parametric study suggest that the pipeline's capacity to accommodate reverse fault offset can be increased significantly by choosing a near-parallel orientation in plan with respect to the fault line. Further improvement in the response of the pipeline is possible by adopting loose backfill, smooth and hard surface coating, and shallow burial depth in the fault crossing region. For normal or near normal orientations, pipeline is expected to fail due to beam buckling at very small fault offsets.     

Modeling of energy dissipation in structural devices and foundation soil during seismic loading

Though rocking shallow foundations could be designed to possess many desirable characteristics such as energy dissipation, isolation, and self-centering, current seismic design codes often avoid nonlinear behavior of soil and energy dissipation beneath foundations. This paper compares the effectiveness of energy dissipation in foundation soil (during rocking) with the effectiveness of structural energy dissipation devices during seismic loading. Numerical simulations were carried out to systematically study the seismic energy dissipation in structural elements and passive controlled energy dissipation devices inserted into the structure. The numerical model was validated using shaking table experimental results on model frame structures with and without energy dissipation devices. The energy dissipation in the structure, drift ratio, and the force and displacement demands on the structure are compared with energy dissipation characteristics of rocking shallow foundations as observed in centrifuge experiments, where shallow foundations were allowed to rock on dry sandy soil stratum during dynamic loading. For the structures with energy dissipating devices, about 70–90% of the seismic input energy is dissipated by energy dissipating devices, while foundation rocking dissipates about 30–90% of the total seismic input energy in foundation soil (depending on the static factor of safety). Results indicate that, if properly designed (with reliable capacity and tolerable settlements), adverse effects of foundation rocking can be minimized, while taking advantage of the favorable features of foundation rocking and hence they can be used as efficient and economical seismic energy dissipation mechanisms in buildings and bridges.     

Rapid earthquake loss assessment after damaging earthquakes

This article summarizes the work done over the last decades regarding the development of new approaches and setting up of new applications for earthquake rapid response systems that function to estimate earthquake losses in quasi-real time after an earthquake. After a critical discussion of relevant earthquake loss estimation methodologies, the essential features and characteristics of the available loss estimation software are summarized. Currently operating near-real-time loss estimation tools can be classified under two main categories depending on the size of area they cover: global and local systems. For the global or regional near-real-time loss estimation systems: GDACS, WAPMERR, PAGER, and NERIES-ELER methodologies are presented together with their loss estimations for the 2009 Abruzzo (L’Aquila) earthquake in Italy. Examples are provided for the local rapid earthquake loss estimation systems, including the Taiwan Earthquake Rapid Reporting System, Real-time Earthquake Assessment Disaster System in Yokohama, Real Time Earthquake Disaster Mitigation System of the Tokyo Gas Co., and Istanbul Earthquake Rapid Response System.     

The Influencing Factors of Escaped Radon from the Jiayuguan Fault Zone and Its Earthquake Reflecting Effect

The paper analyzes the radon data of nearly two decades on the Jiayuguan fault zone,discusses the main influencing factors,and puts forward the relationship between radon and air temperature,ground temperature and rainfall.We summarized the earthquake reflecting effect for ML≥5.0 about 400km within the Jiayuguan station,and reached the conclusion that it has better earthquake-reflecting ability before an earthquake,usually appearing as abnormal changes in sustained low value.By extracting the annual trend of radon in Jiayuguan station over many years,we discovered that the annual trend of radon has a close relationship with the seismic activity in surrounding areas,namely,if the annual variation of radon is larger,the seismic activity in surrounding areas is stronger;Otherwise,if the annual variation of radon is relatively stable,the seismic activity in the vicinity is weak.     

基于MATLAB神经网络方法的多层砖房震害预测

提出利用MATLAB人工神经网络工具箱建立基于贝叶斯正则算法的BP神经网络模型,以地震区多层砖房震害调查数据为因子的震害预测方法.神经网络模型输入震害因子包括建筑的层数、施工质量、房屋整体性等,输出值为建筑物在地震作用下的破坏程度.结果表明,本方法可以对多层砖房的震害样本进行预测并达到较理想的效果.     

首都圈跨断层流动形变观测资料映震能力及场地监测能力分析

首都圈最早建立跨断层流动形变监测网始于20世纪60年代末,主要布设在北京周围广大地区,覆盖了主要活动断裂带.在过去的40多年里,首都圈地区及附近发生了多次强震,如1976年唐山7.8级、1989年大同6.1级和1998年张北6.2级地震等.本文首先对首都圈地区的跨断层流动形变观测资料进行了映震能力分析,然后探讨了监测场...     

前兆波及其地震预测意义

通过回顾自20世纪60年代以来地震前兆波的研究与地震预测实践的进展情况,分析利用地震前兆波进行地震预测研究所取得的一些有意义的进展及其在科学上面临的困难,分别对前兆波及其定义、前兆波预测大地震事件基本依据、前兆波观测技术概述、前兆波的地震预测意义进行了探讨.文中定义了地震前兆波,以固体均匀弹性中的介质点波动方程和大量震例总结的前兆波阶段性特征,说明利用地震前兆波预测大地震事件具有坚实的理论基础和实践依据.文中阐述了前兆波观测技术的发展要求,并提出了改变目前的被动观测状况、对观测目标区域发生破坏性地震的短期和临震前兆进行主动观测的科学思路;应强化对地震震源区的观测,利用前兆波携带的信息研究震源及其附近地区的介质参数变化,对实现短临地震预测是有意义的.     

城市小区居民地震灾害认知与响应的初步研究——以宝鸡市宝钛小区为例

城市小区居民地震灾害认知与响应的研究,可为制定防震减灾相关政策提供实证依据.通过问卷调查方式,采用比较分析法,对宝鸡市宝钛小区居民的地震灾害认知与响应状况进行研究.结果表明,居民地震灾害认知与响应的总体水平不够理想,其中在自救互救方面最差,在地震灾害知识方面较好;居民对地震灾害知识了解的准确性欠缺、深度不够,防震减灾技能掌握不足,但有迫切的学习需求;居民自救互救的主动性和组织性较差,互救意识淡薄,地震谣言辨别能力不强,易于传播谣言.因此,充分发挥小区基层机构的宣传、引导、组织和管理作用,提升小区居民对地震灾害的认知与响应水平,是增强城市小区防震减灾综合能力的有效途径之一.     

山西地震应急评估系统模型本地化研究

地震发生时,地震应急指挥技术系统在应急基础数据库的支持下,可以迅速判断地震的规模、影响范围、人员伤亡、经济损失等情况。文章对影响计算结果的破坏矩阵、影响场模型等进行了分析,并分别与历史地震震后实际的灾害损失情况进行对比,以找到适合山西地区的本地化模型参数,为地震应急指挥提供科学的参考依据。