预应力空心板接缝开裂的防治措施

在建筑工程中,使用预应力空心板的建筑工程在交付使用后,往往在屋面顶棚顺预应力楼板交接处容易出现开裂,即通常所说的“板缝”。本文分析了“板缝”产生的原因并提出了采取的预防措施。     

沥青路面产生不平整的原因

结合路面施工中出现的坑凹、接缝台阶、桥涵与路面接茬不平等、路面不平整等现象,具体分析了产生的原因.     

机场混凝土道面接缝研究

机场水泥混凝土道面接缝的破坏直接影响道面的使用寿命和飞机的起降安全;道面接缝破坏后难以修复,投资较大。该文根据大量调研资料得出,接缝的破坏形式有边角剥落、接缝碎裂渗水、唧泥、错台等形式。本文从力学角度分析了应力集中对道面寿命的影响,建议进行倒角施工,来提高飞行安全和延长道面使用寿命。     

沥青路面平整度控制

路面平整度是评定路面质量的主要技术指标之一,它关系到行车的安全、舒适以及路面所受冲击力的大小和使用寿命,对高等级公路来讲,平整度指标就更为重要。影响路面平整度的因素是多种多样的,涉及到设计、施工、自然条件等方方面面。多年来的沥青混凝土施工经验告诉我们,影响沥青混凝土路面平整度的因素从施工角度来讲,主要为不均匀沉降;摊铺工艺;碾压工艺;横接缝处理;配合比设     

Elastoplastic pipe-soil interaction analyses of partially-supported jointed water mains

Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe failure must include both the pipe deterioration model and mechanics model. Winkler pipe-soil interaction （WPSI）, an analytical mechanics model developed by Rajani and Tesfamariam （2004）, takes external and internal loads, temperature changes, loss of bedding support, and the elastoplastic effect of soil into consideration. Based on the WPSI model, a method to evaluate the elastic and plastic areas was proposed in the present study. An FEM model based on pipe-soil interaction （PSI） element was used to verify the analytical model. Sensitivity analyses indicate that the soft soil, long pipe and high temperature induced the axial plastic deformation more likely, which, however, may not occur in normal scenarios. The soft soil, pipes in small diameters, long unsupported bedding are prone to form flexural plastic area. The results show that the pipes subjected to the same loads have smaller stresses in the elastoplastic analysis than elastic analysis. The difference, however, is slight.     

后浇带在建筑施工中的应用

新浇混凝土在硬结过程中会收缩,当其变形受到约束时,在结构内部就产生温度应力,当超长结构不设置伸缩缝或增大结构伸缩缝间距时,必须采取措施,防止结构开裂。建筑物存在高度差,但结构设计根据具体情况可不设置永久变形缝时,也常应用施工后浇带来解决施工阶段的沉降。