软土地基钢筋混凝土板整体基础的小桥涵

湖州市自1984年以来,在软土地基采用钢筋混凝土板整体基础建造小桥涵几十座。使用结果,不但结构可靠、施工方便,而且可降低造价、缩短工期。文章介绍钢筋混凝土板整体基础小桥涵设计采用有限元计算模型进行计算分析;还介绍了4个实例,可供设计人员参考。     

高含冰量冻土地区拼装涵洞施工技术

针对青藏铁路高含冰量冻土地区特殊自然条件 ,改进了拼装涵洞的施工技术 ,在涵节预制、涵节运输、涵洞基础施工、涵节现场拼装方面作了技术改进 ,克服了现浇涵洞作业量大、投入多、保温困难的缺点 ,同时又便于推广新技术、新工艺 .实践证明 ,此施工方法效果良好     

茂名市城区防洪排涝工程涵闸的水力计算

从涵闸水力计算入手，就茂名市城区的雨水外排和洪水外堵问题做一探讨，根据流量将涵闸分成三个流量组进行水力计算，从而选择洞尺寸，经实践证明，该法计算较简便，得出的成果能满定正常使用要求，其防洪排涝效果显著，茂名市城区防洪排涝工程的建设解决了该市防洪排涝的历史问题。     

钢筋混凝土箱涵施工裂缝的分析与控制

结合工程概况,分析了宜万铁路DK17 577.2箱涵侧墙裂缝产生的原因,对其施工方案进行了改进,并给出了裂缝的控制措施,指出应加强各环节的监控管理,以消除裂缝的产生,从而保证了箱涵的施工质量。     

浅议旧路改建工程

结合多年来旧路改建的设计与施工经验 ,介绍了公路改建设计时技术标准的运用、中线及路面结构的类型与材料的选择 ;阐述了如何进行加固、利用和接长桥涵及支挡构造物的验算设计 ,并提出了关键部位的施工工艺等     

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。     

飞机滑行道下的长大箱涵顶进技术

介绍了在首都机场飞机滑行道下施工Ф325mm大管棚的工艺和在管棚支护下顶进长度为148m双孔公路隧道的关键技术。文中涉及顶进前的超前支护、顶进中的周边土体稳定和道面沉降控制,以及带坡双向顶进中的箱涵顶进姿态的调整等施工技术。     

压力箱涵的裂缝控制及防渗措施

介绍了压力箱涵在施工过程中产生裂缝的原因及特征，提出了一些控制裂缝的具体措施，并从设计、施工两方面阐述了工程中应采取的防渗措施，确保了工程质量。     

山区公路高填方涵洞加筋桥减载方法及其设计理论研究

提出了高填方涵洞加筋桥减载方法及加筋桥减载原理,通过模型试验证明了高填方涵洞加筋桥减载的有效性及影响加筋桥减载效果的因素。根据加筋桥减载原理和模型试验结果,建立了加筋桥减载的结构力学模型,推导了加筋桥减载结构设计的计算公式,包括加筋桥的加筋设计荷载计算公式、加筋桥的数量(层数)计算公式、加筋桥的锚固长度计算公式以及加筋桥的加筋长度(跨径)计算公式等,为加筋桥减载结构设计提供了较全面的理论计算依据,并通过现场涵洞测试证明了加筋桥减载的良好效果。模型试验和现场测试表明,加筋桥减载具有减载效果好、施工工艺简单和结构性能安全可靠等优点,不但适用于高填方涵洞减载,而且适用于其他各种填埋式地下洞室的减载。     

Influence of longitudinal structural connectivity on seismic performance of three-hinged precast arch culverts

The hinge type of precast concrete arch culvert was introduced to Japan from France in the 1990s in consideration of the saving of labor, shortening of the construction period, and high quality control of the concrete members. However, due to the 2011 off the Pacific Coast of Tohoku Earthquake (March 11, 2011), the three-hinged precast arch culverts that had been constructed in Japan at the beginning of the period when precast arch culverts were firstly introduced, suffered damage, which spoiled their serviceability. According to the extent of the damage and the type of culverts that were damaged, the longitudinal structural connectivity of the culverts was assumed to be one of the possible reasons for the reported damage mechanism. Therefore, the objective of this paper was to clarify how strongly the longitudinal structural connectivity influenced the longitudinal seismic behavior of the three-hinged arch culverts. To achieve this objective, an elasto-plastic finite element analysis was conducted with an analytical model that could capture the characteristics of the damaged culverts. Simultaneously, a penalty method with the bi-linear spring model was applied as a solution to the contact-impact problems of the precast segmental arch members. As a result, it was found that the weaker longitudinal structural connectivity in the damaged culverts allowed the torsional displacements of the arch members to induce critical damage to the arch members, namely, edge defects in the arch crown and concrete foundation. The numerical results proved the unignorable influence of the longitudinal structural connection on the possible damage to three-hinged arch culverts.