共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
3.
混凝土内出现的裂缝按深度的不同,分为贯穿裂缝、深层裂缝及表面裂缝三种。为了保证出现最少的裂缝,就必须在混凝土施工时掌握它的基本性能,并根据实际应用情况采取有效措施,以确保施工质量。 相似文献
4.
5.
针对某空心板桥梁在施工中出现锚端裂缝的问题,结合施工经验,分析裂缝产生原因,指出裂缝对梁承载力和正常使用的影响,提出了具有针对性的处理防范措施。 相似文献
6.
7.
8.
混凝土进入冬期施工,受气温影响,属于裂缝多发期。文章分析混凝土冬期施工裂缝产生的特性及原因,提出了相应的控制措施。 相似文献
9.
针对水泥稳定基层易产生裂缝而影响路面使用寿命这一不容忽视的问题 ,通过对水稳基层裂缝形成的机理、产生裂缝的原因及危害进行分析、探讨 ,提出从优选原材料、执行施工规范、严格控制施工质量等方面入手 ,采取有效的预防措施 ,从而减少或避免水稳基层产生裂缝。 相似文献
10.
杨敏 《内蒙古林业调查设计》2011,34(1):126-128
文章根据全现浇钢筋混凝土楼屋面板的裂缝,现结合内蒙古林区十多年来大量施工实践中的经验和教训,以及裂缝的防治处理,重点介绍以施工为主、兼顾设计和材料原因分析楼面裂缝的综合性防治及具体措施。 相似文献
11.
12.
沥青路面表面纵向与横向疲劳裂缝扩展研究 总被引:1,自引:0,他引:1
基于自上而下的表面纵、横向疲劳裂缝严重影响沥青路面的使用品质,首先分析表面疲劳裂缝的形成机理,然后采用奇异等参元法及断裂力学理论,应用有限元软件ABAQUS,建立20结点等参立方体单元的有限元模型,数值计算路面表面纵、横向疲劳裂缝扩展,探讨表面纵、横向裂缝疲劳扩展的规律。计算表明:①表面纵、横向裂缝扩展只考虑偏载作用,随着裂缝向下扩展,其K2是增大到一个峰值后,再由此下降。裂缝扩展前期,纵、横向裂缝的K2差别不大,而在中后期,纵向裂缝的K2要大于横向裂缝。②各路面结构参数中面层厚度h1和模量E1及基层模量E2对表面纵、横向裂缝扩展影响较大,其它参数(土基模量E0、底基层厚度h3和模量E3、基层厚度h2)则影响很小。 相似文献
13.
14.
混凝土裂缝自动愈合机理研究 总被引:4,自引:0,他引:4
通过对混凝土裂缝渗水量影响因素的研究,确定了单位渗水量与裂缝宽度等的关系曲线,以及混凝土裂缝可能产生自愈合的时间及裂缝宽度;还对混凝土裂缝自愈合机理进行了研究。 相似文献
15.
砌体结构的房屋在中小城市建筑物中占的比例较大,分布较广,而砌体结构中的一般细小裂缝由于不危及使用,往往被人忽略.但这些裂缝在较长时间内还不稳定,降低了建筑物的抗震能力,在地震时容易引发墙体破坏,甚至墙体倒塌,必须重视解决.本文根据本人几年的工作经验,提出自己对砌体结构裂缝产生的原因及其防治的浅显建议. 相似文献
16.
Under varying climate conditions, cracks are commonly observed in bolted joints, owing to the shrinkage of wood and confinement from slotted-in steel plates and bolts. A three-dimensional finite element model was developed to investigate the mechanical behavior of bolted glulam joints with initial cracks. Wood foundation was prescribed in the model to simulate the local crushing behavior of wood surrounding the bolts. The behavior of wood in compression and the foundation were defined as transversely isotropic plastic in the software package ANSYS. Cohesive zone model was applied in the numerical analysis to consider the propagation of initial cracks and brittle failure of wood in the bolted joints under tension load. The numerical model was validated by the experiments conducted on full-scale specimens and it is indicated that the numerical model has good ability in predicting the failure modes and capacity of tension joints with local cracks. To further investigate the influence of crack number, length and locations, a parametric study was conducted with the verified model. Moreover, to study the effects of cracks on the behavior of bolted joints with different failure modes, another bolted joint including bolts with different strength grades and diameters was designed and analyzed in the parametric study, which was expected to have bolt yielding failure mode. It was found that the initial cracks can decrease the capacity and initial stiffness of tension joints by up to 16.5 and 34.8%, respectively. 相似文献
17.
《Wood material science & engineering》2013,8(4):335-343
AbstractMost of the cracks are caused by changes in temperature and relative humidity which lead to shrinkage and swelling of the wood and thereby induce stresses in the structure. How these cracks influence the strength of the wooden structure, especially the shear strength, is not well understood. However, it is reasonable to expect that cracks have an impact on the shear strength as they preferably run along the beams in the direction of grain and bond lines. The purpose of this study was to investigate the load-bearing capacity of cracked glulam beams and to find a model that could predict the failure load of the beams due to the cracks. Three-point bending tests were used on glulam beams of different sizes with pre-manufactured cracks. An orthotropic elastic model and extended finite element method was used to model the behaviour of the cracked beams and to estimate the load-bearing capacity. The conclusions were validated by numerical simulations of the mechanical behaviour of three-point bending of glulam beams with different crack locations. The crack initiation load was recorded as the failure load and compared to the experimental failure load. The results of the compaction simulations agree well with the experimental results. 相似文献
18.
本文结合杭州湾跨海大桥Ⅰ合同段桥墩的施工情况,介绍了海工高性能混凝土的施工特点,对杭州湾跨海大桥中桥墩混凝土裂纹成因进行了分析,并介绍了其预防和处理措施。 相似文献
19.
This paper presents a method for detecting gullet cracks in a bandsaw during sawing by monitoring burst-type acoustic emission (AE) signals with large amplitude. The amplitudes of the AE signal and profile height amplitude distributions based on roughness profiles of the sawn surface were compared for the bandsaw with and without gullet cracks. The amplitudes of the AE signal increased and the sawn surface quality became worse with the increased number of gullet cracks in the bandsaw. 相似文献
20.
The development of cracks and changes in appearance have been investigated on radial and tangential sections of pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) after exposure outdoors for 61 months. The degradation of the sections has also been studied at the micro-level. The annual ring orientation was the most important factor affecting crack development on weathering. After 61 months of outdoor exposure, the tangential sections of spruce had 1.7-2.2 times greater mean total crack length per area unit than the corresponding radial sections. In pine, the total crack length per area unit on the tangential sections was 2.2-2.6 times greater than that on the radial sections. Tangential and radial sections show the same colour change as a result of weathering. Tangential sections have more and deeper cracks than radial surfaces. The cracks on the tangential sections occur frequently in both earlywood and latewood. On radial sections, cracks occur primarily at the annual ring borders, but to a certain extent also in the earlywood. Decomposition of the cell wall takes place in both radial and tangential cell walls, and cracks tend to follow the fibril orientation in the S2-layer of the cell wall. The radial cell wall of the earlywood has a large number of pits which are degraded at an early stage. 相似文献