Collapse safety margin-oriented seismic retrofit strategy for corroded reinforced concrete frames using fibre reinforced plastics

Considering residual service life, this paper presents a collapse safety margin-oriented seismic retrofit strategy for corroded reinforced concrete (RC) frames using fibre reinforced plastics (FRP). With the assumed uniform corrosion model, corrosion-induced initial damage combined with subsequent earthquake-induced damage is identified by the multi-mode-based global damage model developed previously. The collapse-level earthquake intensity determined by incremental dynamic analyses (IDA) with the damage model and the maximum considered earthquake (MCE)-level intensity considering residual service life are combined to generate the time-variant collapse safety margin assessment of corroded RC structures. Based on this assessment, the collapse safety margin-oriented FRP seismic retrofit strategy is proposed and demonstrated on a 4-storey frame. The damage model originally developed for earthquake scenarios has also exhibited its rationality for characterising corrosion-induced initial damage and its influence on coupled damage development with subsequent earthquake excitation. Seismic retrofitting with FRP composites should consider the effects of the corrosion development stage, target collapse safety margin and residual service life. FRP retrofits can cause decreases in the MCE-level collapse probability and increases in the collapse resistance of corroded RC structures. Retrofitting carried out at different times achieves different efficiencies and different time-variant collapse safety margins within the residual service life.     

逐级加载下浅埋软岩隧道动力破坏振动台试验

浅埋隧道围岩的质量普遍较低,整体稳定性差,隧道震害表明强震作用下浅埋隧道极易发生震动破坏。通过开展V级围岩条件下浅埋隧道在小震下的震动响应和逐级加载下的震动垮塌振动台试验,研究了小震作用下围岩加速度沿地层的分布、衬砌结构的内力变化和围岩内部的水平位移变化规律,强震作用下衬砌结构裂缝开展和围岩震动垮塌。结果表明:围岩加速度随距地表距离的减小而增加,地表加速度约为拱顶处加速度的1.63倍,相同高度平面内靠近隧道的围岩振动具有一定的加强;隧道拱顶围岩内部的水平位移大约是拱腰围岩内部的1.23倍,围岩内部位移随着远离隧道而逐渐减小,随着震动烈度的增加而不断增加;隧道拱顶上方垮塌区形状近似漏斗,震动引起隧道衬砌结构拱脚处的轴力和弯矩变化最大,且拱肩和拱脚处裂缝分布最多,应加强拱肩和拱脚处结构的抗震性能。     

方钢管混凝土柱-组合梁框架抗连续倒塌性能试验研究

为了研究组合梁对方钢管混凝土柱-组合梁框架抗连续倒塌性能的影响,设计了带有混凝土现浇楼板方钢管混凝土柱-组合梁框架(CFSTCBF)及不带楼板的方钢管混凝土柱-钢梁框架(CFSTSBF),采用拆除构件法对两个试件的抗连续倒塌性能进行竖向加载试验研究,对其在中柱失效工况下的破坏模式、受力机理以及主要的抗力机制进行分析,同时对现浇混凝土楼板和节点在连续倒塌过程中的性能进行探讨。研究表明：两个试件的破坏均是由正弯矩区钢梁破坏引起,结构的倒塌阶段可分为弹塑性阶段、塑性阶段、过渡阶段和悬链线阶段,压拱机制和悬链线机制均能改善结构的抗倒塌性能;混凝土楼板可以有效增强结构的承载能力,提高结构的初始转动刚度,但在改善结构变形能力方面的作用较弱。     

盲谷水库防渗处理——云南五里冲水库工程简介

云南五里冲水库是我国在岩溶地区利用盲谷采用以灌浆为主,结合堵、截进行防渗处理,首次建成的水深超百米的无坝中型水库.帷幕灌浆工程量21.6×104m,单层帷幕深160m,地下溶洞内建造了高100.4m,长50m,厚2.0～2.5m的钢筋混凝土防渗墙;在岩溶塌陷体内用高压灌浆建造帷幕.     

严重垮冒主溜井新型加固方法的研究与实践

针对程潮铁矿2号主溜井垮落后的稳定状况,提出了“托斗”结构为主要支护形式的总体返修加固方案,实践证明,该方案不仅工期甜酸、投资和,而且溜井返修后稳定性良好,为严重垮冒主溜井结构的恢复提供 了新方法。     

隧道开挖过程中层状围岩稳定性分析

结合工程实例，基于块体的失稳条件和层状岩体的破坏条件，分析不同地质构造形态岩层下，隧洞开挖过程中围岩的稳定性。并根据洞室围岩产状与开挖几何边界的关系，提出围岩易破坏点的位置确定方法。最后，通过对工程实例中围岩塌方的统计，分析塌方围岩原因，进一步验证层状岩体中围岩的稳定性评价。     

采场安全监测与冒顶预报

本文总结了声发射现场监测预报的试验结果，提出了采场稳定性预测的综合方法，应用灰色理论预测和神经网络方法较好地解决了采场冒顶预报问题。     

钻孔灌注桩施工中几个技术问题的处理

施工中如何控制灌注桩的质量是保证桩基工程质量的重要环节。结合江苏省防汛物资储运码头工程施工实践，针对钻孔灌注桩施工中遇到的几个技术问题，提出了切合实际的处理办法，以供参考。     

The Effect of Pore Morphology on Hot Spot Temperature

Composite explosives contain pores that collapse under shock wave interaction generating localized regions of heat known to be important in the initiation of high explosives. Understanding pore collapse under shock loading is essential to create predictive reactive flow models to simulate the initiation process. While spherical pore collapse has been thoroughly simulated, other geometries have been relatively neglected. Simulating microoscale hot spot nucleation, we analyze the effect of pore morphology on the post‐shock hot spot temperature. Several pore morphologies that yield higher temperatures than the spherical case are revealed and discussed. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE‐AC52‐07NA27344.     

煤层开采推过陷落柱矿压显现规律数值模拟研究

以成庄煤矿KDX118陷落柱为例,根据物探勘测的结果,对推测为不富水,不具有导通性的KDX118陷落柱进行采动过程的动态模拟。通过Flac3D数值模拟,展示了综放工作面平推过陷落柱情况下的采场破坏情况和矿压应力变化情况。探讨推过陷落柱过程中的应力集中规律,为能够在安全开采前提下尽量回收煤炭资源,优化工作面方案提供参考依据。利用观测结果对该矿处理陷落柱方式的可行性进行论证,为该矿下一步生产提供一定的技术参考。