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摘自《山区建筑》地圈梁、雨棚、檐口板、现浇楼面板、屋面板等在浇捣混凝土后一、二天,多则三、五天,在没有任何外荷载的情况下就发生了开裂。过去有的人认为,地圈梁早期开裂是因为基础沉降。经对涪陵地区427厂宿舍的地圈梁开裂问题的调查分析,地圈梁开裂的原因并非是地基沉降,而是混凝上收缩所引起的。许多实践证明,混凝土在空气中硬结时会发生体积收缩,在水中硬结时会发生体积膨胀现象。而且收缩值比膨胀值要大得多。当混凝土中有钢筋存在时,对混凝土的收缩有很大的影响,钢筋会阻止混凝土收缩,使混凝上受拉,引起初应力,甚至会发生早期裂缝(即在浇灌后一、二天便
Taken from “mountain building”, the ring beams, canopies, sampan plates, cast-in-place panels, roof panels, etc. occurred one or two days after concrete pouring, and as many as three or five days, it took place without any external load. Cracking. Some people in the past believed that the early cracking of the ring beam was due to foundation settlement. After investigating and analyzing the problem of cracks in the floor beam of the 427 factory dormitory in Fuling District, the cause of the cracking of the ring beam is not the foundation settlement but the shrinkage caused by the coagulation. Many practices have shown that when the concrete hardens in air, it will shrink in volume, and when it hardens in water, it will expand. And the contraction value is much larger than the expansion value. When steel is present in the concrete, it has a great influence on the shrinkage of the concrete. The reinforcing steel will prevent the concrete from shrinking, causing the concrete to be pulled, causing initial stress, and even early cracks (that is, one or two days after watering).