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我厂在长期的排水管外压试验中发现:管子破坏荷载一般均能满足设计要求,裂缝荷载次之,唯安全荷载值波动较大,往往低于设计值。1981年我厂减薄管壁厚度,将覆土4米改为3米后,此矛盾更为突出。我们曾采取提高混凝土强度、调整工艺等多种方法,但效果并不明显。原因何在?为此,我们在外压试验过程中进行仔细观察,发现上述矛盾主要系由管表状态不良造成的。由于我厂管模陈旧,变形严重,致使管体表面大多出现三种不良状态: 1.管表凹凸不平。此种管子在受荷时,压板、垫板与管体不是密切贴合(沿整个管体轴向线接
Our long-term external pressure test of the drainage pipe found that: pipe failure load can generally meet the design requirements, fracture load is secondary, and only the safe load value fluctuates greatly and is often lower than the design value. In 1981, the thickness of the pipe wall was reduced by the factory. After the 4 m of earth-covered soil was changed to 3 m, this contradiction became even more pronounced. We have adopted various methods such as improving the strength of concrete and adjusting the process, but the effect is not obvious. What is the reason? To this end, we carefully observed during the external pressure test and found that the above-mentioned contradiction was mainly caused by the bad state of the tube sheet. Due to the obsolete and severely deformed pipes in our factory, the surface of the pipe body mostly appears three kinds of bad states: 1. The tube surface is uneven. When the tube is under load, the pressure plate, backing plate and tube body are not closely attached (along the entire axial direction of the tube body