浅埋偏压连拱隧道的施工优化及支护受力特征分析

用岩土工程专用分析程序FLAC3D,对铜黄高速公路汤屯段富溪浅埋偏压连拱隧道进口段采用的施工过程进行了三维快速拉格朗日差分方法分析,比较了先开挖浅埋侧主洞与先开挖深埋侧主洞两种开挖施工顺序,获得了浅埋偏压连拱隧道在采用不同开挖顺序施工时各阶段隧道变形、中隔墙及支护结构的应力和位移等变化情况,通过对比、分析,从而使得实际隧道施工顺序得到优化,结果与现场监控量测资料相比较,得出的结论可为富溪浅埋偏压连拱隧道施工提供科学依据与技术指导。     

真空预压中地下水位测试技术探讨与改进

阐述了地下水位的基本概念,分析了大气压状态和真空状态下地下水位的特征,认为地下水位就是重力水面,即重力水与毛细水的分界面。在大气压状态下,零压线就是地下水位;在真空状态下,零压线不是地下水位。根据受力平衡方程和气体状态方程,分析了传统测试技术存在的问题,认为传统水位测试管无法测得真实的地下水位,当水位管敞口时,所测得水位高度是零压线高度,水位变化实质上反映水位管滤管段的孔隙水压力平均消散情况;当水位管口密封时,也因无法保证水位管与加固区内膜下具有相同的真空度,导致测试结果具有较大的误差,且随着测试次数增多而增大。为此,提出了一种新的利用水位管内孔压计和真空表的读数计算得到真实地下水位变化值的测试技术,该技术能连续测试地下水位而不影响其测试结果。     

渤海海冰漂移过程的数值模拟和试验

建立了一个包含潮流作用的准定常海冰动力学模式，利用实测风资料和计算的潮流场对辽东湾中部的冰块漂移过程进行数值模拟，模拟的冰块漂移过程和实况基本一致。表明模式具有反映冰漂移过程动力特征的能力。通过对各动力因子的数值试验，说明引入潮流作用的必要性，并分析了各动力因子在冰漂移过程中的作用。     

The simulation of the geometry of a tuna purse seine under current and drift of purse seiner

It was necessary to obtain a more practical interactive precise model of the three-dimensional (3-D) geometry during purse seine operations considering movements of fishing vessel and details of the sea condition. The changes in the shape of a purse seine from shooting to pursing during pelagic skipjack fishing was recorded in the Southwest Pacific Ocean by photographs of the scanning sonar with in situ measurements of water flow by a current meter. The modeling of 3-D geometry during purse seining was established using finite element methods, as resultant force vector from flow drag, buoyancy, sinking force, tension of pulling or pursing acting on net panels in connection with drift of fishing vessel with time elapsed from the start of shooting to the end of pursing. The simulation results were matched closely by field measurements as a heart-like shape in upper net near floatline and a water-drop shape in purse line following drift of ship towards inside net circle during pursing. This model of a purse seine can be extended to almost any kind of purse seine generating real fishing parameters and to modeling fish capture process.     

Response of tall buildings to base rocking induced by Rayleigh waves

By now, it is well known that long‐period surface waves can induce resonant response in high‐rise buildings, in particular those located in sedimentary basins. Rayleigh wave passage has been reported to induce rocking motion at the base of the buildings which can increase displacement demands significantly. However, the building behavior to base rocking has not been extensively studied because commercially available instruments do not record rotational components of ground motion, and thus, rocking time histories have not been available to the analysts. In a recent study, we proposed an effective method for estimating the rocking associated with Rayleigh waves, which takes into account their frequency‐dependent phase velocities. In the present work, we select a number of recorded seismic motions which include surface waves on sedimentary basins from recent well‐recorded earthquake events. Then, we proceed to identify and extract the recorded surface waves by using the technique mentioned above. Using realistic soil‐structure analytical models that have been proposed in the published literature for high‐rise buildings, we study their response to Rayleigh waves as they respond to both translational and rocking motions. Of particular interest is to compare the response of such structures with and without the presence of rotational motions due to surface waves. Using the roof displacement and the building interstory drift as response quantities, our results indicate that demands are controlled by rotational (rocking) motions associated with Rayleigh waves.     

Seismic drift demands in multi‐storey cross‐laminated timber buildings

This paper investigates the seismic response of multi‐storey cross‐laminated timber (CLT) buildings and its relationship with salient ground‐motion and building characteristics. Attention is given to the effects of earthquake frequency content on the inelastic deformation demands of platform CLT walled structures. The response of a set of 60 CLT buildings of varying number of storeys and panel fragmentation levels representative of a wide range of structural configurations subjected to 1656 real earthquake records is examined. It is shown that, besides salient structural parameters like panel aspect ratio, design behaviour factor, and density of joints, the frequency content of the earthquake action as characterized by its mean period has a paramount importance on the level of nonlinear deformations attained by CLT structures. Moreover, the evolution of drifts as a function of building to ground‐motion periods ratio is different for low‐ and high‐rise buildings. Accordingly, nonlinear regression models are developed for estimating the global and interstorey drifts demands on multi‐storey CLT buildings. Finally, the significance of the results is highlighted with reference to European seismic design procedures and recent assessment proposals.     

中国与新西兰规范中混凝土结构弹性位移角限值及有关影响因素分析

按照中国规范与新西兰规范建立钢筋混凝土框架模型,比较两国规范在正常使用极限状态下弹性位移角限值的宽严程度。就中国规范算例,按照新西兰规范逐个改变设计地震作用、构件有效刚度、隔墙影响和偶然偏心率等因素,分析各因素对结构弹性位移角的影响程度,从而对比两国规范的弹性设计地震作用水平差异。     

高层钢结构建筑横向支撑地震动力响应分析

为测试高层钢结构建筑抗震性能,在有限元模型中以某高层钢框架结构办公大厦作为研究对象,测试其横向支撑地震动力响应状况。选取地震峰值加速度为200 cm/s^2的El-Centro波作为地震波输入,采用瞬态动力方法分析不同楼板厚度下建筑地震模拟响应,得到建筑顶层位移时程曲线;在SAP2000结构软件中分析建筑工程添加横向支撑前后的反应谱,记录各楼层垂直与水平方向位移与层间位移角。得到如下结果:高层钢结构建筑在地震响应下产生的位移不随楼板厚度的增加而增大,楼板厚度为100 mm、170 mm时位移波动显著;添加横向支撑后,建筑水平刚度显著提升,同理,添加横向支撑后横向层间位移角的最大值变化较大,且低于1/250,符合相关建筑标准。     

基于多元模糊的钢筋混凝土结构地震抗损性评估方法研究

评估钢筋混凝土结构抗损性具有重要工程意义,但目前以单因素叠加为基础的评估方法误差较大。为解决此问题,提出基于多元模糊的钢筋混凝土结构地震抗损性评估方法。以Park-Ang地震损伤模型为前提,引入正规化累积耗能参数,得到建筑结构层间损伤表达式,加权平均获取震后建筑结构整体损伤值;利用有害层间位移角参数计算震后结构层间位移角;将获取的结构整体损伤值、层间位移角作为多因素论域,进行多元模糊结构抗损性评估,选取模糊损伤评估数学模型与隶属度函数,克服单一因素影响,计算判别因素权重与结构综合损伤指数,根据结构抗损性能判断规则得到建筑结构抗损性所属标准。经实验测试验证:基于多元模糊的钢筋混凝土结构地震抗损性评估方法精确度大于95%,评估精确性高,是一种有效的钢筋混凝土结构抗损性评估方法。