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本文分析了无损检测技术的意义和桥粱常见裂缝的危害,并总结混凝土裂缝检测与监测的方法,最后介绍裂缝的修补及加强技术,供大家参考。 相似文献
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一直以来,混凝土裂缝是困扰建筑业多年的质量通病,如裂缝较多、较深,将直接影响结构安全。本文阐述了混凝土裂缝的类型,分析了裂缝形成的主要原因,在此上提出了控制要点。 相似文献
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由于受自身及外界各种因素的影响,在混凝土的浇筑过程中常常会产生~些缺陷,裂缝是最常见的缺陷形式之一。在不破坏混凝土的情况下,通过声波反射法的测试对不同类型混凝土裂缝的发育深度及空间分布等情况进行检测,在实际工程应用中取得良好效果。 相似文献
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裂缝是混凝土构件普遍存在的一种现象,铁路桥梁、隧道、涵洞的裂缝屡见不鲜,裂缝的出现,降低结构的防水性、耐久性和承载能力,也给结构的整体外观造成了不良影响。如何阻止或减缓裂缝的产生和发展以及裂缝出现后及时整治,并且不影响桥梁结构的安全和使用寿命,是一项严峻、紧迫而又复杂的系统工程。 相似文献
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住丹江口大坝加高工程上游老坝体表面裂缝处理施工过冲中,采用了“坝而防渗+缝而局部灌浆+缝而增加排水仰孔”的综合处理方案,成功修复了坝体的裂缝,并根据后期钻孔取芯试验成果表明了裂缝修复取得的良好效果,该项施工工艺对我国处理水工混凝土建筑物的病害起到一定的参考意义。 相似文献
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《Cement and Concrete Composites》2007,29(9):700-711
Surface opening cracks are common defects in large civil structures like bridges. They allow penetration of water or other agents that result in loss of durability earlier than expected. Their repair can be conducted by the injection of epoxy material that seals the crack sides keeping out any aggressive substances in addition to the recovery of strength. In order to evaluate crack parameters before impregnation as well as to determine the final repair effectiveness, a combination of Rayleigh and longitudinal waves is applied. Rayleigh waves demonstrate the filling condition of the material into the shallow layer near the surface while tomography using longitudinal waves through the thickness yields information about the area inside the structure. Wave propagation dispersion features are exploited by the proposed tomography at different frequencies, demonstrating that higher frequencies lead to more accurate characterization. 相似文献
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预应力T梁束孔管道压浆质量的无损检测试验研究 总被引:6,自引:0,他引:6
采用探地雷达技术、超声波透射法等多项技术方法对T梁的压浆质量进行试验性检测研究.首先采用超声波透射法在未压浆的钢束管道位置和正常混凝土位置(即避开波纹管位置)进行测试,然后将这两种类型的测试数据结果作为学习样本提供给神经网络进行学习;再将已压浆预应力T梁上的实测结果作为网络测试数据进行计算,根据神经网络的计算结果可预测钢束管道内的压浆质量,判断管道中是否有空隙存在.根据检测结果和开窗验证的情况来看,超声波透射法检测和神经网络的预测结果是准确可靠的,探地雷达技术不适合于T梁束孔管道的压浆质量检测. 相似文献
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T. C. CHIVERS 《Fatigue & Fracture of Engineering Materials & Structures》2002,25(11):1095-1102
ABSTRACT Leak‐before‐break (l‐b‐b) safety cases depend on predictions of flow rate through postulated cracks. The calculated flow rates are dependent upon assumptions made about a number of features including fluid friction, and this in turn is influenced by surface roughness and flow regime. This paper considers the uncertainties associated with flow rate prediction in both the laminar and fully rough turbulent regimes as influenced by fluid friction. It shows how uncertainties can be bounded. In particular it discusses the maximum values for fluid friction that might arise in practice. The use of computational fluid dynamics in future analyses could significantly reduce the uncertainties associated with fluid friction in cracks. 相似文献
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通过5根嵌入不同张拉控制应力的碳纤维增强塑料预应力混凝土棱柱体(CFRP-PCPs)复合筋加固钢筋混凝土梁受弯试验,对比分析试验梁的裂缝分布与发展,得到最大裂缝宽度与平均裂缝宽度在静力荷载作用下的变化特性。结果表明: 嵌入CFRP-PCPs复合筋能有效的减少被加固钢筋混凝土梁的裂缝宽度和高度。在试验基础上,根据国家现行混凝土规范,对平均裂缝间距和最大裂缝宽度计算公式进行参数修正,建立了CFRP-PCPs复合筋嵌入加固钢筋混凝土梁最大裂缝宽度计算公式,计算值与试验值吻合较好。 相似文献
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Results on an investigation dealing with the effect of metakaolin (MK) on the near surface characteristics of concrete are presented in this paper. A control concrete having cement content 450 kg/m3 and w/c of 0.45 was designed. Cement was replaced with three percentages (5, 10, and 15%) of metakaolin weight. Tests were conducted for initial surface absorption, sorptivity, water absorption and compressive strength at the ages of 35, 56, and 84 days. Test results indicated that with the increase in MK content from 5 to 15%, there was a decrease in the initial surface absorption, decrease in the sorptivity till 10% metakaolin replacement. But at 15% MK replacement an increase in sorptivity was observed. All mixtures showed low water absorption characteristic i.e. less than 10%. Compressive strength shared an inverse relation with sorptivity. Higher MK replacements of 15% are not helpful in improving inner core durability, even though it helps in improving surface durability characteristics. 相似文献
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Maintenance and rehabilitation of concrete structures affected by alkali-aggregate reaction (AAR) require conducting detailed
assessment of the concrete conditions, mainly close to the surface where the damage is more severe. This paper presents in
situ investigations by surface wave testing of near-surface AAR damage in two hydraulic structures. The survey was carried
out using a non-intrusive multi-sensor method that involves frequency–wavenumber analysis of surface waves. The method allows
solving Rayleigh surface wave propagation modes required for the determination of the shear wave velocity in terms of depth.
The variation of Young’s modulus with concrete depth can be estimated from the obtained shear wave velocity profile. Two different
cases of surface wave propagation, typical of concrete structures, are discussed in this paper. The tests were conducted from
the concrete surface only and the subsurface quality was mapped up to a depth of 1.50 m. The applications show that the proposed
surface wave method is a potential non-destructive evaluation method that can be used to detect and locate near surface damage
in concrete structures.
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The influence of fly ash on the fresh properties, mechanical properties and carbonation properties were studied in this paper. The performance of a kind of curing agent which was applied to the hardened concrete surface was evaluated. Incorporating large volume of fly ash will risk the concrete carbonation. And the curing agent could prevent the concrete carbonation. And the mechanism was explained. 相似文献
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裂缝的存在加速混凝土中氯离子的侵蚀速度,进而加快钢筋混凝土结构力学性能的劣化速度,因此钢筋混凝土结构耐久性设计中需要考虑裂缝的影响。现有文献中关于裂缝对氯离子扩散行为定量影响的试验结果具有很大的离散性,给出的拟合公式带有局限性。对此,该文建立了一个统一的裂缝中氯离子扩散系数Dcr与裂缝宽度wcr之间的定量关系式。该关系式各参数具有明确的物理意义,对应的曲线圆滑且不存在拐点。与已有试验数据吻合良好,验证了公式的合理性。数值模拟了开裂混凝土中氯离子扩散行为,数值结果与文献结果吻合良好,证明了方法的有效性。 相似文献