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在汶川地震作用下,北川县城的建筑物遭到严重损毁.为给北川县及邻近区县防灾规划和工程抗震设防提供科学参考,本次研究在现场实地调查的基础上,对北川县城建筑物损毁机制与县城地质条件之间的关系进行分析,结果表明,北川县城建筑物损毁是由地表破裂、滑坡、崩塌、地表震动等多种破坏机制综合作用的结果.结论:在北川及邻近区县防灾规划中,建筑物的修建应尽量避开断裂展布带、崩滑灾害易发区段等可能对建筑物造成毁灭性破坏的区域,对于已建成区附近的灾害易发点也应采取必要的工程措施加于防治. 相似文献
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《东南大学学报》2016,(4)
为研究钢筋销栓作用的疲劳承载性能,制作了9个钢筋混凝土试件分别进行静载试验和疲劳加载试验.试件共分为2组,首先通过6个试件的静载试验确定销栓作用的极限承载力,其钢筋直径分别为12,20和25 mm;然后通过3个试件的疲劳加载试验来研究疲劳荷载作用下销栓作用承载性能的衰减特征及疲劳破坏形态.试验结果表明,在疲劳加载的过程中,疲劳损伤的积累会降低销栓作用的承载能力.在正常使用状态下,即极限承载力的55%,随着疲劳循环次数的增加,销栓作用的破坏模式会发生转化.疲劳破坏形态表现为钢筋的瞬时断裂,其疲劳寿命由钢筋和混凝土的材料性能所决定.基于试验结果,可以将钢筋销栓作用的疲劳破坏过程分为2个阶段,分别为损伤积累阶段和瞬时断裂阶段. 相似文献
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目的:本文旨在建立简单实用的饱和软黏土不排水强度损伤弱化模型,应用于波浪循环荷载作用下沉箱式防波堤与软土地基相互作用的非线性数值计算,为解决防波堤软土强度弱化计算问题提供有效途径。创新点:1.基于不排水强度循环损伤弱化机理,得到软黏土不排水强度随循环荷载作用次数和应力水平的变化规律;2.结合Tresca屈服准则进行数值开发,应用于波浪循环荷载作用下沉箱式防波堤与软土地基相互作用的数值计算。方法:1.引入累积塑性变形相关的损伤变量表征土体结构性的损伤和重塑对软黏土不排水强度弱化的影响(公式(3)和(11));2.建立软黏土不排水强度随循环荷载作用次数和应力水平变化的损伤弱化模型(公式(14));3.结合Tresca屈服准则,实现软黏土不排水强度损伤弱化的数值计算过程(图9);4.针对烟台软黏土动三轴试验数据进行分析,对模型及其数值开发过程进行验证(图11和12);5.将模型应用到软土地基上沉箱式防波堤数值运算,分析软土地基响应,验证模型的有效性(图15~18)。结论:1.在临界循环应力比以下,损伤变量和归一化最大孔压比随循环荷载作用次数的增加逐渐增大,并趋于稳定;随循环应力比增大逐渐增大。循环后不排水强度折减系数随着循环荷载作用次数和循环应力比的增加而减小。2.有限元数值开发过程是正确的,不排水强度损伤弱化模型是合理的。3.该模型简单实用,可应用于波浪等循环荷载作用下沉箱式防波堤与软土地基相互作用的非线性数值计算,且能模拟循环荷载下软土地基的孔隙水压力增长以及不排水强度弱化等响应。软土地基的响应主要分布在基床两趾及正下方的软土层上部。 相似文献
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动静载荷耦合作用下岩石破坏过程研究是深部开采等相关岩土工程的应用基础性研究课题.本文对动静载荷耦合作用下岩石破坏过程研究现状进行了分析,并对该领域今后的研究方向进行了探讨. 相似文献
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研究了采用离心模型试验来研究波浪与土相互作用的方法,并针对渤海某油田的波浪及土质条件进行了试验研究.结果表明,在最大波高作用下,软粘土层的上部发生了软化,但这种影响随着深度的增加而逐渐减小;在波浪荷载的作用下,软粘土层下的粉砂层没有液化迹象. 相似文献
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车金如 《温州职业技术学院学报》2005,5(4):23-25
建筑物内发生火灾，会对建筑结构产生损伤和破坏，但是其损伤程度有轻有重。修复建筑物损伤时，应根据各种结构的特点及火灾损伤的程度，因地制宜地选择不同的修复方法加固补强。 相似文献
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实验教学是高等教育的重要环节,在培养学生的动手能力与创新能力方面有不可替代的作用,又因波浪运动特性对港口水工建筑物、海洋工程结构物的稳定有着重要的影响,是港航工程专业的主要学习内容之一。论文针对波浪运动特性实验,结合专业教学特点和要求,进行了实验教学改革的探索与实践,对实验指导教材进行了整编,并制作多媒体课件帮助学生自主学习,通过对教学模式及考核模式的改革,使实验从课前预习至课后总结形成了一个有机的整体,选做实验更增强了学生研究的积极性,培养了创新思维。结果表明,实验教学改革提高了学生分析和解决问题的能力,取得了良好的教学效果。 相似文献
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为了避免因沉降原因造成建筑物主体结构的破坏或产生影响结构使用功能的裂缝,造成巨大的损失,必须应用沉降观测加强过程监控,指导合理的施工工序,预防在施工过程中出现不均匀沉降,本文对此方面做了重要研究. 相似文献
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Analysis of structural response under blast loads using the coupled SPH-FEM approach 总被引：3，自引：0，他引：3
A numerical model using the coupled smoothed panicle hydrodynamics-finite element method （SPH-FEM） approach is presented for analysis of structures under blast loads. The analyses on two numerical cases, one for free field explosive and the other for structural response under blast loads, are performed to model the whole processes from the propagation of the pressure wave to the response of structures. Based on the simulation, it is concluded that this model can be used for reasonably accurate explosive analysis of structures. The resulting information would be valuable for protecting structures under blast loads. 相似文献
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研究目的：通过非线性动力有限元分析,模拟多塔斜拉桥在多点激励下的地震响应以及揭爪其在强震下的倒塌破坏模式。创新要点：解决了多塔斜拉桥的非线性动力数值模拟技术,并首次模拟了多塔斜拉桥在强震下的破坏模式。研究方法：首先采用隐式的Newmark-β法求解多点地震激励下的非线性动力方程（图3）,随后采用显式的中心差分格式对强震作用下桥梁的倒塌破坏过程进行数值仿真（图4）。重要结论：1．单主梁模犁的数值结果可以很好地反映地震模拟振动台试验的地震响应结果;2．在加速度峰值为4．0m／s2的E1。Centro波时,多塔斜拉桥模型只出现了中塔支座的破坏;3．在加速度峰值为4．0m／s2的江心波时,多塔斜拉桥模型先后出现了支序破坏、拉索与塔的连接破坏以及中塔上塔柱段的单元失效。 相似文献
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基于压电体中的压电本构方程,给出了应力波在含石英等压电介质脆性岩体中的传输效应,计算得到了各种应力波幅值和频率对其辐射的电磁波强度和频段间的关系,并阐明了压电体中应力波和电磁波的耦合机制。在此基础上,对于几种不同晶系结构,给定应力波形式的前提下,指出了压电应变矩阵对压电介质中应力场和电磁场的耦合行为所起的决定性作用。本文的研究结果能较好解释地震和岩石动力破裂过程中的声电光现象。 相似文献
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TABESHPOUR M.R. GOLAFSHANI A.A. SEIF M.S. 《浙江大学学报(A卷英文版)》2006,7(8):1305-1317
INTRODUCTION There is obvious demand for oil exploitation in deep water. Increasing water depth will make the environment more severe and so some innovative structures are required for economic production of gas and petroleum in deep water. An engineering idea is the minimization of the structure resistance to en-vironmental loads by making the structure flexible. This structural flexibility causes nonlinearity in the structural stiffness matrix because of large deforma-tions. Wave loadi… 相似文献
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Rafael L. Irizarry 《International Journal of Educational Development》1983,3(2):163-181
Academics, foundations and international agencies concerned with development have repeatedly pointed out the failure of educational institutions to support economic development in underdeveloped countries, particularly in providing the occupational skills and research knowledge in science and technology required by the productive sectors of the economy. The causal factors of this failure have been attributed to institutional deficiencies and traditionalism of backward societies where ‘desk’ jobs and independent professions enjoy higher esteem than technology-related occupations.This paper argues that such educational patterns are rooted in the structures of dependency of the underdeveloped countries. First, employment is concentrated in the non-productive services sector of the economy where desk jobs abound. Second, dependent industrialization entails the predominance of external linkages of industry to developed countries, and technological dependency both in its organic and intellectual components. Industry in underdeveloped countries does not carry out the more complex technological operations of the production cycle or research and development activities for new technology, both of which are done in developed countries. In the absence of this activity, educational institutions cannot ‘learn’ and keep abreast of the modern technological knowledge and processes required for jobs in industry. 相似文献
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GEBBEKEN Norbert 《天津大学学报(英文版)》2006,12(Z1)
The identification of the critical infrastructure has shown that the build civil engineering infrastructure is almost involved everywhere, even with the IT-infrastructure. Therefore, the passive safety of structures is demanded. Security associations have analysed that most assaults came along with explosion and impact scenarios, which amount in 80% of assaults. Consequently, these are the extraordinary loads the structures have to be planned and designed for. To carry out such an engineering job, the engineer has to be educated in multiple disciplines as physics, material science , continuum mechanics, numerical mechanics, testing, structural engineering and related specific fields as wave propagation etc. In this paper we will concentrate on the subjects of numerical simulation and testing. 相似文献
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GEBBEKEN Norbert 《天津大学学报(英文版)》2006,12(B09):1-7
The identification of the critical infrastructure has shown that the build civil engineering infrastructure is almost involved everywhere, even with the IT-infrastructure. Therefore, the passive safety of structures is demanded. Security associations have analysed that most assaults came along with explosion and impact scenarios, which amount in 80% of assaults. Consequently, these are the extraordinary loads the structures have to be planned and designed for. To carry out such an engineering job, the engineer has to be educated in multiple disciplines as physics, material science, continuum mechanics, numerical mechanics, testing, structural engineering and related specific fields as wave propagation etc. In this paper we will concentrate on the subjects of numerical simulation and testing. 相似文献
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Spallation mechanism of RC slabs under contact detonation 总被引：2，自引：0，他引：2
The spallation of the concrete slabs or walls resulting from contact detonation constitutes risk to the personnel and equipment inside the structures because of the high speed concrete fragments even though the overall structures or structural members are not destroyed completely.Correctly predicting the damage caused by any potential contact detonation can lead to better for-tification design to withstand the blast loadings.It is therefore of great significance to study the mechanism involved in the spallation of concrete slabs and walls.Existing studies on this topic of-ten employ simplified material models and 1D wave analysis,which cannot reproduce the realistic response in the spallation process.Numerical simulations are therefore carried out under different contact blast loadings in the free air using LS-DYNA.Sophisticated concrete and reinforcing bar material models are adopted,taking into account the strain rate effect on both tension and com-pression.The erosion technique is used to model the fracture and failure of materials under tensile stress.Full processes of the deformation and dynamic damage of reinforced concrete (RC) slabs and plain concrete slabs are thus observed realistically.It is noted that with the increase of quantity of explosive,the dimensions of damage crater increase and the slabs experience four different damage patterns,namely explosive crater,spalling,perforation,and punching.Comparison be-tween the simulation results of plain concrete slabs and those of RC slabs show that reinforcing bars can enhance the integrity and shearing resistance of the slabs to a certain extent,and mean-while attenuate the ejection velocity and decrease the size of the concrete fragments.Therefore,optimizing reinforcement arrangement can improve the anti-spallation capability of the slabs and walls to a certain extent. 相似文献