Assessing the Vibrational Frequencies of the Holweide Hospital in the City of Cologne (Germany) by Means of Ambient Seismic Noise Analysis and FE modelling

Ambient seismic noise measurements were conducted inside the Holweide Hospital (Cologne) for checking whether its frequencies of vibration fall into the range where soil amplification is expected. If this is the case, damage might increase in case of an earthquake due to an amplified structural response of the building. Two different techniques were used: the ratio between the horizontal and vertical components of the spectra recorded at stations located inside the building and the ratio between the corresponding components of the spectra recorded simultaneously inside the building and at a reference station placed outside. While the former method might be preferred because of less equipment involved, the latter has the advantage of producing more stable results and deleting automatically the influence of the sedimentary cover, which might obscure some eigenfrequencies of vibration of the building. An independently performed finite-element analysis of the hospital showed a good correlation between measured and calculated eigenmodes.     

变刚度钢管混凝土短柱隔震结构弹塑性动力分析

采用HBTA2.5程序,对一变刚度钢管混凝土短柱隔震结构进行了弹塑性时程分析。分析结果表明,其隔震装置的水平变形和耗能能力可以大大减轻地震对结构的影响。提出钢管混凝土短柱隔震结构在工程应用将有很好的发展前景。     

甘肃金川矿区构造应力场与构造演化研究

文章统计分析了金川矿区内地层和侵入体中的节理构造,对矿区内的共轭剪节理进行配套、分期,综合区域构造演化史后分析了矿区构造应力场。研究表明,金川矿区从新太古代到古生代至少受到4期古构造应力的作用。第一期构造应力场为NS向的挤压,由阴山陆块与鄂尔多斯陆块碰撞形成华北古陆西部陆块引起。第二期构造应力场为NE-SW向的挤压,与华北克拉通东、西陆块碰撞拼合并参与Columbia超大陆拼合事件有关;其后阿拉善陆块与华南陆块参与Rodinia超大陆拼合事件,应力场持续作用。第三期构造应力场为近NS向的挤压,由祁连洋不断向北俯冲引起。第四期构造应力场为NNE-SSW向的挤压,与祁连造山带发生的强烈造山运动有关。     

Some recent advances in the modelling of soft rock joints in direct shear

This paper presents a review of recent developments made by the authors into the modelling of rock joints in direct shear. Careful observation of laboratory direct shear testing on concrete/rock joints containing two-dimensional roughness has allowed theoretical models of behaviour to be developed. The processes modelled include asperity sliding, asperity shearing, post-peak behaviour, asperity deformation and distribution of stresses on the joint interface. Model predictions compare extremely well with laboratory test results. These models were then applied to direct shear tests on rock/rock joints, and although behaviour in general was well predicted, the strength of rock/rock joints was over-predicted. Direct shear tests have also been carried out on samples containing both two- and three-dimensional roughness to test the accuracy of the two-dimensional approximation to roughness adopted in the theoretical models.     

锚拉杆张拉力和摩阻力的现场实验研究与分析

对锚拉桥台锚拉杆进行了２０小时的现场试验,获得了大量实验数据,对张拉后锚拉杆的张拉力与长度、时间、温度和焊接接头的关系以及土对锚拉杆的摩阻力变化及分布规律作了分析与研究。研究结果对指导该类构筑物的设计与施工有着重要的理论与工程实用价值。     

新型预制装配式楼盖抗倒塌试验研究

地震及爆炸荷载下的结构连续倒塌问题对人民的生命财产造成重大威胁,是土木工程领域研究的一个热门方向。为了提高新型预应力空心楼板结构的整体性,防止由于竖向支承构件的失效形成楼板的局部或者连续倒塌,对2块新型预应力空心板足尺模型进行四分点静力加载试验,研究新型预制装配式两跨连续楼板的抗连续倒塌能力。试件均由预应力空心短板通过板端伸出U形筋和胡子筋进行对接连接,板侧纵向拼缝通过胡子筋和植筋与边梁的纵筋进行连接,2个试件的计算跨度相同。本文采用在加载过程中突然拆除中间支座,得到楼板破坏形态、裂缝发展、承载能力、应变、最大变形等试验结果。对试件的受力过程、悬索作用机理进行分析,最后得到楼盖拼缝及板侧边梁连接构造的布置合理,新型预制装配式楼盖采用合适的周边连系和横向拼缝连接可以达到理想的抗倒塌能力。     

含两组交叉贯通节理岩体的强度及破坏特征分析

天然岩体中常含有多组相互交叉的贯通节理,它们的存在极大地削弱了岩体的力学性质。为了研究含两组交叉贯通节理岩体的强度及破坏特征,基于弹塑性数值流形方法,对不同应力状态下,节理倾角和节理间距不同的岩体压缩试验进行数值模拟。结果表明：岩体强度随节理倾角的变化曲线呈现出多波峰、多波谷特点,岩体强度随节理间距变化曲线符合负指数函数形式。根据节理状态,两组节理岩体的破坏模式可以分为3种：岩块破坏、沿一组节理滑移和沿两组节理滑移。两组节理均会影响岩体强度,一组起主要作用,另一组起次要作用,并且节理组之间存在相互影响。通过对数值计算结果进行回归分析,基于一组节理岩体强度预测模型,量化节理组之间的相互影响,提出适用于含两组交叉贯通节理岩体的强度预测模型。模型形式简单,使用方便,可为实际工程中正确评估岩体强度提供指导性意见。     

西秦岭北缘漳县含盐红层盆地构造分析及古构造应力场反演

对漳县含盐红层盆地的构造节理、褶皱等构造形迹进行野外观察、测量、分期配套,应用吴氏网赤平投影法来反演古构造应力场。分析表明,漳县红层盆地白垩系沉积地层形成后至少经历了4期构造活动：第一期构造应力场的最大主压应力方向为NW-SE向,第二期构造应力场的最大主压应力方向为NE-SW向,第三期构造应力场的最大主压应力方向近E-W向,第四期构造应力场的最大主压应力方向近S-N向,4期构造应力场中间主压力轴（δ2)多近于直立。反演结果显示,该区域自白垩系沉积后区域构造特征以走滑作用为主。     

PHC管桩单桩振动台试验与数值模拟对比分析

利用振动台对PHC管桩进行单桩承台模型试验;同时将土体PHC管桩-上部结构视为共同工作整体,建立三维有限元模型,再以ABAQUS软件为计算平台,对单桩试验工况下的地震反应进行数值模拟计算,并将试验结果与数值模拟计算结果进行对比分析。结果表明：数值模拟和振动台模型试验基本吻合,两者得到的地震反应影响体现出相似的规律性,印证了模型试验的可靠性和数值模型的合理性。