管道工程中基于LiDAR的高精度DEM获取

LiDAR技术的广泛应用对空间信息获取手段产生了重大影响,使得DEM的获取更加快速,精度更高,而成本更低。本文以西气东输四线管道工程LiDAR点云数据处理工作为基础,着重探讨了基于LiDAR的高精度DEM获取技术,给出了具体的工作流程,并对所获得DEM成果做了精度分析,对推动我国LiDAR技术的发展做了有益的实践。     

非开挖地下管线修复与更换技术在中国的应用前景

改革开放以来,我国大部分城市抓住发展契机都在搞建设,但计划赶不上变化快,地下管道在建设过程中缺乏长远考虑,遗留了诸多问题。当前,部分管道老龄化,破损严重,急需修复与更换。我们国家多采用明挖法进行施工,而国际上很多国家则运用非开挖地下管线修复与更换技术,与明挖法相比有保护环境,不影响交通,施．Y-隐蔽,社会效益高,技术先进等优点。这项技术在我国还处于初级阶段。技术经验不足,大多需要借用国外的设备。由于我国大城市管道陈旧和道路交通拥堵现象日趋严重,发展该技术迫在眉睫。国际上常用的修复技术有内衬插入法,模压内衬法,折叠内衬法,螺旋缠绕法等。这些方法各有优点,而“刮痧法”和“穿衣法”能兼并其中几种方法的优点。在我们国内市场,运用以上方法成功的案例也有,但并未得到推广。非开挖地下管线修复与更换技术出了应用于市政工程外,还可用于石油管线工程,地质工程等,在国内有巨大市场前景。     

非开挖施工地下管线的改进措施

非开挖施工地下管线有很多工艺方法,这些工艺中存在某些需要改进的地方。并且在适当条件下可以采用新的方法代替现有的方法。第一是非开挖施工“超重地下管道”时,拉管工序中的局部连接新方法的设想。第二是在特殊情况下施工地下电力管线时PE管管节连接方式的选择。第三是在合适的地层中采用“拔管法”更换废旧地下管线的施工工艺。     

非开挖施工前的管道探测方法

只有在非开挖施工前探明了地下管线的分布情况,才能正确地制定施工方案,以防止对已有的地下管线造成破坏,引起人员伤亡和重大财产损失。通过对传统的和在当今比较前沿的几种地下管道探测方法做出介绍,旨在为施工人员在地下管道探测作业时提供更多的选择。     

成都市地震烈度速报台网建设与思考

汶川8级大地震后,因交通、通讯中断等多种原因,无法及时确定地震灾区受灾范围与震害程度,给党和政府指挥抗震救灾带来了困难,为此,成都市在实施灾后重建项目时,建立了以地震烈度速报为目标的地震烈度速报台网,在破坏性地震发生后,能快速获取灾区的受灾范围和破坏程度等重要信息,为抗震救灾提供科学决策依据。     

Adjusting Chlorine Dosage and to Prevent Bio‐Growth and Minimize Trihalomethanes in Reverse Osmosis Filtrate in a Wastewater Reclamation Process

Feasibility of effluent reclamation for the Futian municipal WWTP in Taichung Taiwan was evaluated using an “SF‐UF‐RO” pilot plant. The optimal parameters of each unit were obtained during the pilot plant test. The pilot plant started the operation in late October 2008 and operated until January 2011. The reverse osmosis (RO) system produces 75 m³ water daily, and the produced water quality was comparable to the city water in Taichung. Chlorine dosed in the sand filtration (SF) inlet and ultrafiltration (UF) backwash had the most significant effect on the stability of system performance. When the chlorine was underdosed, biofilm clogged the bag filter (prefilter of UF) and led to the flow rate decay of the UF. The prefilter needed replacement every 1 or 2 weeks resulting in increased process cost. On the other hand, when the chlorine dosage was increased to mitigate the biofilm growth, the residual chlorine not only reacted with TOC and derived trihalomethanes (THMs) in the RO product water (more than 20 µg/L), but it also damaged the RO membrane. After trial and error, the chlorine concentration was optimized as 0.7 mg/L in SF inlet to prevent growth of biofilm as well as to control the residual chlorine in the RO inlet and THMs in the RO product water. It is suggested that cautiously adjusting chlorine dosage is essential for stably operating such a hybrid membrane system to reclaim the municipal wastewater.     

中俄原油管道沿线多年冻土环境及管道施工技术探讨

选取中俄原油管道沿线位于多年冻土区的漠河-乌尔其段为研究区域, 分析了管道工程对多年冻土环境的影响以及冻土退化所带来的一系列生态环境问题, 并研究了冻土环境变化对管道工程的影响. 针对冻土区管道工程施工的相关问题, 提出了不同施工迹地的施工方式及相对应的冻土环境保护措施: 施工作业带的清理;取弃土的处理;施工便道、伴行道的修建及不同地段施工便道与伴行路路基最小高度的确定;施工营地、料场的设计及布设;管沟开挖时基坑暴露时间的计算, 多年冻土区管道工程的施工等.中俄输油管道是我国首条通过多年冻土区的大口径原油管道, 研究结果可为中俄输油管道及今后寒区工程建设过程中的环境保护提供科学依据.     

应对汶川特大地震波及乐山事件的做法及思考

2008年5月12日汶川8.0级地震是有史以来对乐山市波及范围最广、人员伤亡最多、经济损失最大、社会影响最强烈的地震。本文回顾了近几年乐山市在地震应急准备方面所做的工作和汶川特大地震波及乐山后的应急工作,认为坚持不懈地抓好地震应急准备是做好大地震之后应急工作的重要前提,及时有效地开展应急工作是防震减灾部门的重要职责,震后恢复重建中防震减灾部门可以发挥重要作用。     

Field and large scale laboratory studies on dynamic properties of emplaced municipal solid waste from two dump sites at Delhi,India

Dynamic properties of municipal solid waste (MSW) from two dump sites located at Delhi, India are evaluated from field and large scale laboratory tests. Shear wave velocity (V_s) profiles of MSW, measured at these two sites using surface wave techniques, are in range of V_s data reported for MSW landfills worldwide. Representative bulk MSW samples were collected from large test pits excavated at the two dump sites to determine the near surface unit weight. Large scale undrained cyclic triaxial (CTX) tests were conducted on reconstituted MSW specimens to investigate the effect of various parameters such as composition, confining pressure, number of loading cycles, loading frequency and saturation on the dynamic properties. Undrained CTX tests, conducted on the specimens with and without fibrous materials demonstrated the effect of fibrous waste constituents on the stiffness and damping behavior of MSW. Specimens consisting of fibrous waste constituents such as plastics and textiles exhibited significantly less modulus reduction compared to specimens with negligible amount of fibrous content. The modulus reduction (G/G_max) and material damping ratio curves derived from the present study are in the range reported for MSW in the literature. The G/G_max curves from present study are in good agreement with curves recommended for MSW at Tri-Cities landfill in USA and Tianziling landfill in China. Dynamic properties evaluated from the present study add to the growing database of the worldwide dataset and can be useful for evaluating the seismic stability and associated permanent deformations of the existing dumps in and around Delhi.