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1、0解读悬臂施工桥梁 0 号块裂缝分析及施工控制中英文Cantilever bridge construction of No. 0 block crack analysis and construction control分析悬臂施工桥梁 0 号块混凝土表面产生裂缝的原因及机理，在武西高速公路黄河大桥悬浇箱梁 0 号块施工中，有针对性的采取了一定的措施，有效的防止了混凝土表面裂缝的产生。The reason and mechanism analysis of Block 0 of the concrete surface cracks in cantilever bridge construc
2、tion in west the Yellow River, Wu highway bridge cantilever box girder Block 0 construction, targeted to take certain measures, effective to prevent the generation of cracks on concrete surface.1 裂缝的种类及成因Types and causes of 1 cracks1.1 荷载引起的裂缝1.1 load induced crack1.1.1 设计阶段有关应力状态未计算或漏算，特别是钢筋设置偏少，或应
3、力集中部分钢筋遗漏，导致在这些部位产生裂缝，0 号块件上这种类型的裂缝主要会产生在支座部位。1.1.1 design stage of the stress state are not calculated or missed, especially reinforced set is less, and the stress concentration part of reinforced omission, resulting in cracks in these parts, crack of Block 0 pieces of this type mainly occur in bea
4、ring parts.1.1.2 施工时对块件顶部随意增加或改变施工荷载，导致块件内部出现裂缝。1.1.2 construction of the block top arbitrarily increase or change the construction load, leading to block internal cracks.1.1.3 局部集中力的作用点，如竖向预应力筋开洞处，有的 0 号块在腹板部位还有横向预应力筋，并在腹板处留有张拉孔，拆模张拉后，容易沿着开洞的某一导角发生裂缝。Effect of 1.1.3 locally concentrated force, such
5、 as vertical prestressed reinforcement of openings, some 0 blocks in the web site and transverse prestressed reinforcement, and stretching hole is left in the web, stripping tension, easily along a guide opening angle crack.1.2 温度变化引起的裂缝Cracks caused by temperature change 1.2http:/ http:/ 0 号块件表面裂缝的
6、主要原因。在施工阶段引起 0 号块内外温度变化主要因素是混凝土凝固过程中产生的水化热、天气骤然降温及昼夜的较大温差，采用电热法张拉预应力构件时，预应力钢材温度可升高至 350，混凝土构件也容易开裂。The temperature change is the main reason to produce 0 pieces of the surface crack. In the construction phase of Block 0 of internal and external temperature changes caused by factors is to produce con
7、crete solidification process of hydration heat, the weather suddenly down the large temperature difference between day and night, using electric heating method prestressed component, temperature prestressed steel can be increased to 350 , concrete is easy to crack.1.3 混凝土收缩引起的裂缝1.3 concrete shrinkag
8、e crack在实际工程中，混凝土因收缩所引起的裂缝也是常见的。在混凝土收缩种类中，塑性收缩和缩水收缩（干缩）是发生混凝土体积变形的主要原因。塑性收缩发生在施工过程中、混凝土浇筑后 4h5h 左右，此时水泥水化反应激烈，分子链逐渐形成，出现泌水和水分急剧蒸发，混凝土失水收缩，同时骨料因自重下沉，因此时混凝土尚未硬化，称为塑性收缩。塑性收缩所产生量级很大，可达 1%左右。在骨料下沉过程中若受到钢筋阻挡，便形成沿钢筋方向的裂缝。缩水收缩（干缩）发生在混凝土结硬以后，随着表层水分逐渐蒸发，湿度逐步降低，混凝土体积减小，称为缩水收缩（干缩） 。因混凝土表层水分损失很快，内部损失慢，因此产生表面收缩大、
9、内部收缩小的不均匀收缩，表面收缩变形受到内部混凝土的约束，致使表面混凝土承受拉力，当表面混凝土承受拉力超过其抗拉强度时，便产生收缩裂缝。In practical engineering, concrete crack caused by shrinkage is also common. Shrink kind in concrete, plastic shrinkage and shrinkage shrinkage (shrinkage) is the main cause of the occurrence of volumetric deformation of concrete. P
10、lastic shrinkage occurs in the process of construction, concrete pouring 4H 5h, the cement hydration reaction fierce, molecular chain is formed gradually, appear secrete water and moisture to evaporate sharply, shrinkage of concrete and aggregate due to weight loss, sink, because the concrete has no
11、t yet hardened, known as the plastic shrinkage. Plastic shrinkage produced large amount, up to about 1%. In the aggregate sinking process if the reinforced block, forming cracks along the reinforcement direction. Shrink contraction (shrinkage) occur in the concrete results hard then, along with the
12、gradual evaporation of surface moisture, humidity gradually reduced, the volume of concrete is reduced, called shrink http:/ http:/ 2contraction (shrinkage). Moisture loss soon, the internal loss of slow, resulting in surface shrinkage, internal shrinkage of non-uniform shrinkage, constrained by the
13、 internal shrinkage deformation of concrete surface, the surface of the concrete under tension, when the surface of the concrete under tension over its tensile strength, produce and shrink the crack.1.4 支架模板变形引起的裂缝The 1.4 bracket template deformation cracks caused by1.4.1 支架竖向支撑及横向固定不牢固，在混凝土浇筑完成后，支架
14、发生不均匀沉降及发生水平位移，则混凝土在强度形成过程中会出现裂缝。1.4.1 support vertical support and lateral not firmly fixed, in the concrete pouring completed, stent occurred uneven settlement and horizontal displacement of concrete strength, in the formation process of the cracks will appear.1.4.2 模板支撑不牢固或对拉镙丝变形，在混凝土浇筑过程中出现胀模等现象
15、，导致混凝土出现裂缝。 The 1.4.2 template support is not firm or to pull the screw deformation, mould expanding phenomenon appears in the concrete pouring process, cracks in concrete. 1.5 施工工艺质量引起的裂缝，在此不一一赘述。Cracks caused by construction process quality in 1.5, not one one of them.1.5.1 混凝土保护层过厚，或乱踩已绑扎的上层钢筋，使承
16、受负弯矩的受力筋保护层加厚，导致构件的有效高度减小，形成与受力钢筋垂直方向的裂缝。1.5.1 concrete protective layer is too thick, or trample has been lashing top bars, make the stress under negative moment reinforcement protective layer thickening, leading to effective height component decreases, crack formation and reinforced vertical.1.5.2 混凝土振捣不密实、不均匀，出现蜂窝、麻面、空洞，导致钢筋锈蚀成为荷载裂缝的起源点。1.5.2 concrete vibrator is not dense, uneven, honeycomb,
