Controlled blasting of concrete

In an old concrete building made available by the Stockholm Real Estate Office, several experiments at full‐scale were made on different methods of localised cutting, including controlled blasting with charges inserted into drilled holes and with lay‐on, metal‐enclosed explosives. Some punching shear to the rear of the wall was noted with the latter, which sometimes produced violent shock waves. The inserted charges performed well, however, and were found to be more economical and environmentally better than conventional cutting methods. The author works at the Swedish National Testing Institute.     

延长盾构机刀具使用寿命的措施

对盾构刀盘和刀具进行了针对性的论述,在盾构刀盘、刀具的设计开发过程中,通过分析刀盘和刀具的受力状况,统计刀盘和刀具的损坏形式,对刀具进行了有针对性的研究改进,从而使产品质量、性能更加可靠完善。     

典型钢梁与箱型柱采用梁翼切削或梁翼加盖板抗弯接头的破坏模式

本文主要介绍二十二组钢梁与箱型柱抗弯接头试体的耐震行为与破坏模式,其中十七组试体采用梁翼切削(reduced beam section,RBS)式接头,另五组以梁翼加盖板的补强(enlarged beam section,EBS)式接头,所有试体均为梁腹栓接、梁翼焊接(BWWF)的现场施作接头。试验结果显示,七组梁翼切削试体及三组梁翼加盖板试体具有4%弧度层间位移角或3%塑性转角以上的变形能力,此十组试体的平均梁塑铰应变硬化系数为1.22。由试体破坏形式归纳,造成梁柱接头变形能力不足的破坏模式包括:梁翼板全渗透焊道断裂、梁翼板于梁腹扇形开孔尖端附近断裂、梁翼切削段内断裂、柱内横隔板与柱板间焊道破坏、及柱板冷(氢)裂五类。探讨此试体破坏原因发现,在六组钢梁与柱内横隔板电溶渣焊焊道侧接合的试体中,三组试体破坏发生于电溶渣焊与柱板接合界面附近,破坏机率高达50%,此现象应值得钢构业重视。本研究成果也发现,高达55%试体未满足台湾钢结构设计规范3%塑性转角或美国AISC耐震特别规定4%层间位移角的变形需求,此显示钢梁与箱型柱采用梁翼切削或加盖板抗弯接头的设计、施工与检测技术有相当大的改善空间。     

Water and Sewerage Charges in Scotland

The paper outlines the statutory arrangements governing water and sewerage charges in Scotland, and comments on the factors affecting the levels of charges. Trends in revenue expenditure over the period 1989–90 to 1992–93 are considered in relation to increases in personal community water charge levels, metered water rates, and costs per household. Non-domestic sewerage rates and industrial effluent charges are also discussed. Some comparisons are made with England and Wales and with other countries. The funding arrangements for capital expenditure and their effect on the levels of charges are described, with particular reference to debt levels and rising expenditure to meet UK and EC standards. Factors affecting future charge levels are also identified.     

考虑黄河冲刷要求的盾构法隧道最小覆土厚度分析

 针对兰州地铁1号线下穿黄河段盾构法隧道的最小覆土厚度问题,基于高压富水弱胶结砂卵石地层特性,分别提出由盾构掘削面稳定性与盾尾后方隧道抗浮稳定性决定的最小覆土厚度的修正算法,明确盾尾后方隧道受到的总浮力可以归纳为因浆液包裹产生的静态上浮力,以及地层应力引起的竖向不平衡力对应的动态上浮力,计算发现隧道抗浮稳定性要求的最小覆土厚度明显大于1.0 D(D为隧道直径),《地铁设计规范》(GB50517-2003)提出一般不宜小于1.0 D的最小覆土厚度有待进一步完善。在考虑隧址附近既有桥墩影响条件下,得出考虑冲刷要求的隧道最小覆土厚度方案是安全可行的,同时明确既有构筑物局部冲刷对新建构筑物的影响。研究结论可为盾构法隧道浅覆土穿越江河的稳定性控制奠定理论基础。     

城市隧道爆破对附近地表的振动监测与影响分析

对某现场爆破振动地表振动速度峰值监测结果进行了研究,拟合得到了地下工程岩石开挖爆破地面振动速度的变化规律,并对同断面、同药量、同测点掏槽爆破地表质点振速和非掏槽地表质点爆破振速进行比较,结果表明掏槽爆破产生振速较大,合理设计掏槽为关键点。     

超大型瓷套切割研磨芯杆的研究与应用

介绍了超大型瓷套端面切割、研磨芯杆的设计及使用方法。通过对不同切割、研磨工艺结构和种类的优缺点比较,结合超大型瓷套的结构特点及切割、研磨方法,确定了新结构的切割、研磨芯杆。该芯杆增加了延伸杆、保护套和辅助支撑,在实际应用中,能够满足制造工艺要求。加工出的产品满足产品技术要求,解决了超大型瓷套产品制造技术中的断面切割研磨难题。     

谈浮法玻璃生产线上的一种多通道90°转向装置

90°转向装置是浮法玻璃生产线冷端转向输送的专用设备,用于将成品玻璃板转向输送到支线辊道或气垫桌上。文章介绍了一种多通道90°转向装置,是基于平板玻璃轮式转向装置进行的改进,它既满足纵切一刀时2片玻璃板的同时转向输送,也满足纵切两刀时3片玻璃板的同时转向输送。     

管幕内顶进箱涵前端网格横截面尺寸确定

上海市中环线虹许路北虹路下立交工程是目前世界上在饱和含水软土地层中施工的横截面最大的管幕法工程。为保证在管幕内顶进大断面箱涵(前端嵌固钢板制网格框架)的施工过程中开挖面的稳定性,设计合理的网格横截面尺寸十分重要。根据对网格后端开挖面处的土拱效应分析,采用静力平衡条件与土体的剪切强度条件作为基本控制条件,并结合土体的自稳条件,给出了网格横截面尺寸的合理计算方法,以使网格横截面尺寸设计更加合理,最后以实例说明了具体计算过程。     

Generalized equation for calculating rock cutting efficiency by pulsed water jets

One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets are basically used to increase the rock cutting efficiency.However,there are no mature recommendations for selection of rational parameters,and the relationship between indicators of rock cutting efficiency and parameters of pulsed water jet is still not established.In this context,we aimed at developing a generalized equation for calculating rock cutting efficiency,in which all the major parameters in consideration of rock cutting process are included.Then,a calibration of the rational parameters of rock cutting by pulsed water jets was conducted.The results are likely helpful for increasing productivity and reducing energy consumption.     

基于Flac3D软件的某路堑开挖稳定性分析

铁路路堑稳定性是铁路安全的一个重要保障。本文利用Flac3D软件．基于Mohr—Coulomb屈服准则，对某铁路路堑进行了数值模拟计算，以确定其应力、位移状态及塑性区分布情况．进而分析和评价路堑安全性，最后得出Flac3D软件在铁路路堑稳定性分析中应用的合理性和适用性。     

A new method to evaluate roadheader operational stability

Roadheader, one of the mechanized excavation equipments, has an exceptional place among the other excavation methods. Determination of the stability states of the roadheader is an important matter for the efficiency of excavation. For this reason, a new method has been developed to obtain numerical values that indicate stability states of such machines. The method has been developed for both longitudinal and transverse cutting head type machines by establishing stability equations for states of turning around the vertical axis, turning to the side direction, turning to the back direction and sliding in all cutting modes. A computer program based on these equations has been written in C++ programming language. The stability analysis can be made either for one point on the excavation face or whole face. Obtained values can be used to compare the stability states of various roadheaders in the same cutting condition as well as using to compare the stability states of a roadheader. A stability index that has also been established can only be used to compare a stability state of a roadheader in different cutting conditions. The developed methodology was tested in a transverse cutting head type roadheader for arcing, lowering and lifting modes. It has been obtained that the stability state of turning around the vertical axis of the roadheader is the most critical state especially in arcing mode. The effects of the machine design parameters, cutting head and tunnel parameters on the stability of the roadheaders can also be investigated by this method.     

截柱扩跨技术在工程改造中的应用

某三层框架结构,底层需截柱扩跨。工程改造前进行了检测鉴定并对比了设计计算值和现场实测值。正确评估建筑物的结构承载能力,不但可以挖掘潜力,减少投入,也可弥补不足,消除隐患。     

Comparison of seismic and explosive energy in five smooth blasting test rounds

The seismic monitoring and analysis of five smooth blasting test rounds in hardrock (gneiss) is described. The ultimate goal of the test blasts was to avoid large seismic vibration levels. Vibrations were measured with a time resolution of 32,000 samples per second with three-component accelerometers at distances between 3 and 9 m from the charges. Examination of the accelerograms resulted in detection of misfires and sympathetic detonations. Consequently, modifications to the electronic initiation system were made. The radiated seismic energy was calculated for each detonator time step. Comparison between explosive and seismic energy characterizes explosive performance and the success of the blast design.     

大型瓷件的炸裂现象分析及采取的措施

列举了大型瓷件在切割研磨过程中的炸裂现象,从切割研磨操作方面分析了炸裂产生的原因。采取优化切割研磨用芯套,调整主轴转速和进刀速度,增加切割次数,减少单次切割量等措施,基本避免了大型瓷件在切割研磨过程中的炸裂现象。     

土压平衡盾构在上软下硬复合地层中的施工技术

上软下硬复合地层是盾构隧道中的不良地层之一。文章针对这类地层的主要特征,分析了土压平衡盾构机掘进通过时容易产生姿态上抬、刀具损坏、地面沉降、土仓结泥饼、卡螺旋机的风险,提出刀具配置和更换、掘进控制、预设换刀区几方面的对策,并列举了一些对掘进时异常情况的辨别和处理方法,可为类似工程提供参考。     

PDC钻头复合钻进破岩机理及个性化设计探讨

在复合钻进工况下,地面和井下马达的复合驱动虽能使PDC钻头的钻速能得到显著提升,但钻头寿命也会显著缩短。通过研究定向井、水平井下部钻柱的受力变形特性,建立了复合钻进下PDC钻头的运动学模型,研究了转速比、布齿位置、下部钻柱几何状态等对切削齿切削轨迹的影响规律。在此基础上,改进了PDC钻头破岩数字仿真系统,并利用该系统研究了PDC钻头在复合钻进工况下的运动学、切削力学规律以及井底形态特点。研究结果表明:除了高转速因素以外,复合钻进钻头破岩效率增高的主要原因在于PDC钻头切削齿的不平行刮切特性,以及螺杆弯角所导致的钻头牙齿的不均衡切削状态。针对PDC钻头在复合钻井条件下的破岩机理和失效特点,探讨了复合钻进PDC钻头个性化设计的技术思想和实施方法,为复合钻进条件下PDC钻头工作性能的改进提供了理论依据和技术手段。     

一种多功能拟静力试验装置

结构抗震的试验研究是结构抗震理论的重要组成部分.如何更加真实地模拟结构构件的压、弯、剪等多种受力性能以及解决试验加载方式和试验装置的不足等问题,一直困扰着广大土木工作者.为了提高实验室的科研教学能力和实验室使用效益,课题组自行设计、加工制作了一种多功能拟静力试验装置,该试验加载装置及设备主要采用反力墙、大型门架构架,液压伺服加载控制系统及竖向加载系统.通过科学、合理的设计,使得该装置不仅可以完成压弯剪型试验,还可完成剪切型破坏形式的大型试验.同时,该装置安装简单,灵活性强,占用实验场地少,节省空间.其中,装置的竖向加载系统由自行设计、制作的竖向稳压系统和水平滚动装置组成.相比其他传统竖向加载装置,利用杠杆放大及等压原理设计制作的杠杆放大式稳压装置,更好地解决了结构构件试验竖向稳定加载问题.利用这种多功能拟静力试验装置,已完成多项压弯型及剪切型大型抗震试验项目,试验效果理想、数据可靠,解决了部分试验能力不足问题,节约了大量资金.     

OpenGL三维地层切割面的实现技术

探讨利用开放图形库OpenGL实现三维地层显示的途径;讨论三维地层层面构造的插值基本原理;提出了地层的任意方向切割方法,即适用于水平截面和斜截面的网格分割法和适用于竖直截面的交线分割法。将此三维地层切割方法应用于广东省大型水利工程———东深供水改造工程中,实现了三维地层的任意切割,验证了该方法的可靠性和实用性。     

磨料射流切割混凝土的机理及试验研究

笔者通过对后混合磨料水射流切割机理的分析，从理论上探讨了磨料水射流形成的液固两相射流具有一定的冲蚀动能，阐述了高能束液固两相射流产生的冲蚀动能，在大干物料的体积能时，可将其物料切割，并提出了磨料仓中的磨料所处的高度产生的重力因素，高速水射流产生的真空卷吸作用因素，水射流对磨料的冲刷作用使其紊流流动而进入射流中的作用因素。是磨料能够混入射流的动力，并且利用高压水射流切割设备，对三种混凝土试件(C30、C40、C50)进行切割试验研究，分析了改变压力，改变喷嘴横移速度，改变喷嘴靶距等切割参数对其切割深度的影响，得出的结论。可作为设计磨料水射流切割装置的参考依据。