Use of laser interferometry for measuring concrete substrate roughness in patch repairs

The overall success and long-term durability of a patch repair is significantly influenced by the bond developed at the interface between the concrete substrate and the repair material. In turn, the bond strength is influenced by the topography (roughness) of the substrate surface after removal of the defective concrete. However, different removal methods of defective concrete produce substrate surfaces with different topographies. Hence, the ability to measure and characterise the topography of substrate surfaces is of great importance for evaluating the effectiveness of different removal methods. In this paper, the effect of two removal methods: electric chipping hammers and Remote Robotic Hydro-erosion (RRH) on the surface roughness is investigated through the use of a prototype non-contact (optical) laser interferometry measuring device. Laboratory results show that the above equipment can be used to characterise substrate roughness and confirm the ability of RRH to create rougher surfaces as opposed to chipping hammers.     

Impact hammer applications in Istanbul metro tunnels

Hydraulic impact hammers have been used widely in Istanbul metro tunnels since 1992. This paper summarizes recent studies and explains the basic principles of the proper selection of hydraulic impact hammers. First data on 600 different hydraulic impact hammers available in the market are analyzed and the relationships between operational variables, such as hammer operating weight, impact energy, recommended excavation weight and size, are investigated in order to make some recommendations on how to calculate the efficiencies of impact hammers and to select proper hammer for a given job. A detailed study is also realized on Levent–Maslak tunnel drivages. Overall performance of tunnel drivages, the relation between Rock Mass Rating (RMR) and net breaking rate of hammers are also explained and compared with previous results obtained in other hydraulic hammer applications in Istanbul tunnel drivages. It is found that the net breaking rate of an impact hammer decreases linearly with RMR.     

基于SPH粒子法的盲天井掏槽爆破数值模拟

针对上向盲天井掏槽孔爆破效果,运用补偿系数法对周边大空孔孔间距进行计算并进行方案制定,利用光滑粒子流体动力学方法(SPH粒子法)进行数值模拟计算,开展盲天井掏槽爆破周边空孔作用以及补偿系数对爆腔及岩石损伤范围影响研究。研究结果表明:在孔间距一定时,爆腔面积随补偿系数增大呈增加趋势;当补偿系数达到2.42时爆破效果最佳且达到峰值0.54 m²,而后爆破效果作用达到极限,爆腔面积变化趋于稳定;岩石损伤范围因炸药作用效果有限,总体变化范围在10%以内;模拟过程中SPH粒子能良好地模拟出爆破过程中岩石运动状态、空孔填充情况以及岩石损伤范围。所得模拟结果与现场试验爆腔断面面积吻合度高,说明数值模拟计算具有一定的准确性。     

不同距离条件下爆破引起的质点振动频幅分析

论文基于隧道开挖施工爆破震动安全监测,通过质点振动速度峰值及其主振频率分析,论述了不同距离条件下爆破引起的质点振动频幅特性,较为详尽地解释与探讨了爆破震动测试结果,并在分析质点振动速度峰值与距离及环境条件关系的基础上,得出较远距离条件下(220 m～325 m)的质点振动速度峰值的主振频率集中在以35Hz为中心的25～45Hz范围值的结论,同时指出近爆破点区域的爆破地震波衰减速度明显大于较远区域,以及介质特性与距离是加速爆破地震波衰减的主要因素,分析结果也再次证实质点振动速度峰值及其主振频率与爆破规模和环境条件密切相关.     

Experimental and numerical investigation into the non-explosive excavation of tunnels

The use of explosives is restricted on some important holidays, and the handling of unexploded charge is very dangerous. Therefore, an innovative non-explosive technology called instantaneous expansion (IE) was developed for tunneling. IE, whose components are derived from solid wastes such as coal gangue and straw conduces to realizing the reuse of waste. Moreover, its cost is lower than explosives. Blind guns of IE are easy to treat with water. The IE tunneling method is classified into two categories, i.e. IE with a single fracture (IESF) and IE with multiple fractures (IEMF), which are used to form the tunnel cross-section directionally cross-section and to fragment the rocks inside the cross-section, respectively. In this study, the principle of IE tunneling was elaborated first. Then, tunneling experiments and numerical simulations were performed on IE, conventional blasting (CB) and shaped charge blasting (SCB) in comparison. The experimental and numerical results show that IE achieved the best performance of directional rock breaking and corresponded to the most minor excavation-induced damage zone of the surrounding rock. Besides, the tunnel cross-section created by IE was flat and smooth. Comparing IE with CB and SCB, the over/under-excavation area decreased by 64% and 17%, and the excavation-induced damage zone fell by 26% and 11%, respectively. The range of the loose circle is reduced, which is conducive to improving the long-term stability of the roadway. The research provides a safe and economical tunneling method with excellent application prospects.     

Evaluation of the geological condition ahead of the tunnel face by geostatistical techniques using TBM driving data

In tunnel excavation by Tunnel Boring Machine (TBM), it is difficult to grasp the ground condition ahead of and surrounding the tunnel face because the face cannot be observed during tunnel driving. This is the reason why it has not been possible to make the best use of high-speed excavation capability of the TBM, especially in ground under complex conditions. Thus, the TBM Excavation Control System was developed to realize the accurate prediction of the geological condition ahead of and surrounding the tunnel face simultaneously with excavation. The special feature of this system is that geostatistical techniques are introduced into the data analysis using both drill logging data from pilot boring and TBM driving data obtained during excavation, in order to improve the precision of the ground mapping.     

液压桩锤液压系统

液压桩锤诸多的优点使其被称为有发展前途的桩工机械。为此作者从液压桩锤液压系统的基本回路、油路连接基本原则、液压元件选择等方面对其进行了系统的介绍，并分析了几种典型液压桩锤液压回路的主要特点。     

Comparative studies on the performance of a roadheader,impact hammer and drilling and blasting method in the excavation of metro station tunnels in Istanbul

Drilling and blasting is the most widely used excavation method in mining and tunnelling especially in hard rock conditions. But in recent years, the application of roadheaders and impact hammers in hard rock, especially in fractured geological formations has increased considerably. However, it is strongly emphasized that the prediction of the machine performance plays an important role in the time scheduling and in the economy of tunnelling projects and accumulated data will serve a sound basis for performance prediction models.This paper presents information on Istanbul Kadikoy–Kartal metro tunnels which are planned to be constructed in two stages, the first one which is in Kozyatagi–Kadikoy direction and the second in Kozyatagi–Kartal direction. The construction method of the Kozyatagi–Kadikoy station tunnels is first summarized and later, the performance of a roadheader, impact hammer and the results of drilling and blasting methods are compared.The results of this study show that machine utilization time is 28.2% for roadheader and 14.2% for impact hammers. Average net cutting rates (NCR) are 32.26 m³/h for roadheader (218.3 m³/day), net breaking rate (NBR) 13.1 m³/h (45 m³/day) for impact hammers and production rate with drill and blast method (D&B) is found to be 187 m³/day.     

The performance prediction of impact hammers from Schmidt hammer rebound values in Istanbul metro tunnel drivages

The construction of the first metro line in Istanbul was realized between Galata and Beyoglu by a French Engineer Henry Gavand in January 1875. Six different metro projects were submitted since then to the Turkish authorities. The construction of 7-km metro tunnels phase 1 started in 1992 and the metro line of the phase 1 is opened to the service in 2000. The tunnels of the phase 2 between Taksim and Yenikapi are under construction. This paper summarizes the construction methods of the Istanbul metro tunnels, the performance of the impact hammers, the factors effecting daily advance rates and the previous studies on Schmidt hammer test and performance prediction of impact hammers. At the end, a prediction model concerning instantaneous breaking rates of hydraulic impact hammers from Schmidt hammer rebound values is explained in detail.     

光面爆破在薄层岩石中的应用

针对太兴线部分隧道岩性特点,通过对薄层岩性特点分析,介绍了有效控制薄层围岩超挖的光面爆破施工技术,实践证明：采用光面爆破能有效控制周边眼炸药的爆破作用,确保施工安全,减小超、欠挖,加快施工进度,降低工程成本。     

Driven cast-in-situ piles installed using hydraulic hammers: Installation energy transfer and driveability assessment

The ability of hydraulic pile driving hammers to overcome energy losses during freefall enables a greater proportion of the impact energy to be transferred to the pile than is possible with diesel hammers. This percentage, termed the energy transfer ratio, is not routinely measured in practice however, and there is an element of uncertainty regarding appropriate energy transfer ratios to adopt in driveability analyses. In light of such uncertainties, the energy transfer ratios of four- and five-tonne hydraulic hammers were assessed during installation of driven cast-in-situ (DCIS) piles at several sites in the United Kingdom. The piling rigs were fitted with instrumentation enabling the hammer velocity (and hence kinetic energy) at impact to be inferred for each blow during installation, with the corresponding energy transferred to the closed-ended steel installation tube ascertained using a Pile Driving Analyzer. The results of the study showed that energy transfer ratios were strongly dependent on the hammer drop height, with transfer ratios of 90% and above only achievable for drop heights in excess of 50% of the maximum value. Driveability analyses using measured energy transfer ratios from the fieldwork, as well as the traditional method using an assumed energy transfer ratio which is independent of drop height, yielded good agreement with measured driving records at a clean sand site. In contrast, poorer predictions were apparent for both methods at another site, where the coarse-grained strata had higher fines contents and significant layering, with the traditional method (assumed energy transfer ratio) over-predicting the maximum transferred energy and concealing the influence of dynamic soil properties on driveability. The findings of the study would suggest that lower energy transfer ratios may need to be considered in driveability predictions for these pile types (i.e. steel or DCIS piles) if lower drop heights are used during driving.     

黄土隧道设计与施工中的几个问题

通过总结分析黄土地层的饱和、固结、湿陷、可灌性与降排水性等对黄土隧道稳定性的影响,提出了黄土隧道工程中应注意的问题;对黄土隧道衬砌结构设计中需要考虑的侧压力系数、变形模量取值问题,围岩压力计算及围岩与衬砌结构相互作用等问题进行深入剖析,并提出了设计中应注意的问题;对于浅埋黄土隧道,建议采取“拟塌落拱有限元方法”进行分析;以某饱和黄土隧道工程为依托进行了几种常用施工方案的数值对比分析,表明NATM施工、掏槽施工或压桩施工均难以满足成洞条件,且先行降、排水措施和初期喷浆支护难度较大,应采取超前管棚注浆等新工艺才能满足饱和黄土隧洞的成洞要求;针对黄土地层盾构隧道施工,建议采用控制“地层刚度”和修正“盾构工艺参数”的方法来控制地表隆沉。     

上海某游泳馆节能改造方案设计

以上海某游泳馆的节能改造为例,从建筑物用能特点、建筑物周边环境和各项节能技术适用性三方面出发,确定了其节能改造初步方案.经济性分析表明,该节能改造方案能产生明显的节能效果,能带来较好的经济效益.     

民用建筑中供配电系统若干问题的再思考

着重分析和讨论民用建筑电气设计中20kV供电电压等级、单台变压器容量、备用电源和应急电源、自启动柴油发电机组的启动信号、低压断路器与母联断路器的联锁控制、低压断路器电子脱扣器的使用、突然断电比过负荷造成的损失更大的线路过负荷保护等问题,并给出建议。     

短路热稳定校验计算方法分析

在供配电设计过程中,在确定断路器和导线截面后,我们需要对短路情况下导线的热稳定性进行校验。目前断路器具有明显的限流作用,本文阐述限流作用对原有热稳定校验公式中参数取值的影响及短路电流持续时间的不确定性,建议改用允通能量曲线进行热稳定校验,并举例说明。     

Predicting performance of impact hammers from rock quality designation and compressive strength properties in various rock masses

Predicting the performance of the impact hammers is one of the major subjects in determining the economics of the underground excavation projects in which they are utilized. Therefore, researchers have been attracted to developing performance prediction models for these machines. Physical and mechanical properties of rocks have been used to estimate the performance of impact hammers over the last few decades. In this study, the instantaneous breaking rate (IBR, m³/h) of an impact hammer used in construction of Levent-Hisarüstü metro tunnel (Istanbul) is recorded in detail. Sixty rock samples are obtained from tunnel route during the excavation of which the machine is employed. Physical and mechanical property tests are performed on the obtained samples. A data set including uniaxial compressive strength (UCS), rock quality designation index (RQD), Brazilian tensile strength (BTS), density (ρ), Schmidt hammer hardness (SHH), Shore scleroscope hardness (SSH), Cerchar abrasivity index (CAI), and IBR is formed. Regression analysis techniques are applied to the created data set in order to develop a performance prediction model. The investigation results in a model that can predict IBR based on UCS, RQD, and the output power of the impact hammer. The proposed model passes both F-test and t-test at 0.95 confidence level. The soundness of the model is successfully tested against two formerly developed models. Covering a wide range of application and requiring only two of the most common and versatile rock properties as input parameters are the other advantages of the suggested model.     

系列手车柜防误改进

对系列手车柜如何保证柜体防误功能齐全,及非断路器柜隔离触头防误问题,提出完善改进措施:断路器柜加装状态控制开关SA2;断路器柜的位置信号,绿色信号灯HL2亮除表示断路器分闸外,还表示该柜隔离触头已具备操作条件;手车柜增加检修控制开关SA2等,从而提高系统供电可靠性。     

小间距浅埋隧道的支护设计探讨

利用奥地利大型岩土工程有限元数值计算软件FINAL计算结果比较研究认为，在新奥法施工的小间距平行土质浅埋隧道中，对于中间岩柱的支护与设计，只要衬砌受力在合理范围内，不需要特别考虑中间岩柱的稳定性，而对其加设锚杆或者其他支护辅助手段，隧道之问的间距可以达到1．0m，甚至更少。列举了慕尼黑地铁隧道对这一结果的成功应用。对于近距离双孔平行隧道，两隧道相互之间的影响，不仅与围岩类别、隧道间距、开挖和支护方式有关，而且不同的开挖顺序，会有不同的结果。分析结果表明，如果先修建好一孔隧道，再修建另一孔隧道，第---~L隧道的修建会对第一孔隧道，特别是相近一侧有较大的影响，仰拱处容易出现拉应力；如果两孔隧道同时交替掘进，则隧道相互影响较大，第一孔隧道的底部和第二孔隧道的拱部，容易出现拉应力，总体衬砌受力比第一种开挖支护方式要小。两种开挖支护方式中，中间岩柱两侧土体和衬砌均处于受压状态。慕尼黑地铁U6段相距0．8m，两隧道的成功修建和运营，是对本文结论的成功验证。     

浅埋红层软弱隧道围岩破坏特性模型试验研究

软弱隧道围岩浅埋段在施工时极易出现较大变形和塌方破坏事故,已成为隧道工程施工中的难点。依托广(通)—大(理)铁路南华1号隧道工程项目,通过模型试验对滇中典型红层软弱隧道围岩的变性破坏模式及应力扰动特征进行了研究。研究结果表明:隧道开挖容易引起两侧拱腰处岩体与水平方向夹角成45°+?/2的区域内开始出现初始裂缝,并向上延伸至拱顶最终形成高度约为0.5倍洞径的塌落拱;隧道开挖将引起围岩应力重分布,在隧道周边形成一圈应力降低区,在其外侧是应力升高区,而岩体塌落区则位于应力降低区内;为减少围岩塌落破坏风险,一方面应尽早支护成环,另一方面宜对应力降低区岩体进行适当加固,并充分利用岩体的自承载能力。上述研究成果不仅可用于指导本工程的设计与施工,而且也可为今后类似工程提供借鉴和参考。     

遮阳板和内缩窗对建筑外窗太阳辐射的影响研究

遮阳板和内缩窗是我国南方建筑较常采用的一种遮阳形式,为研究这两种遮阳结构对建筑外窗太阳辐射的影响,计算了建筑东、南、西、北外墙上,采用遮阳板的内缩窗的太阳辐射能量。对太阳直射辐射采用投影相加法计算遮阳板和内缩墙面对建筑外窗的遮挡。计算表明:遮阳板和内缩窗可以明显减弱东、南、西侧外墙上窗户的太阳辐射,对北侧外墙窗户的遮阳作用较小。