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一、产生环向断裂的原因环向断裂有两种情况:一是在覆土前出现,二是覆土后发生,以前者为多。 1.覆土前环向断裂石棉水泥管在未覆土时,顶部暴露在露天,底部与土接触,常产生环向断裂。断裂的部位多靠近刚性接头,春秋两季严重。经现场分析,主要系空气介质温度变化和管材周围干湿度不均所致。西北地区昼夜气温悬殊,初秋季节中午高达35℃左右,晚上室外则降到5℃左右。按此温度计算,温度应力可达72.9公斤/厘米~2,而石棉水泥压力管的极限抗拉强度只
First, the reasons for the occurrence of circumferential rupture There are two situations of circumferential failure: First, before the overburden, and second, after the overburden occurs, the former is more. 1. If the asbestos-cement-cement pipe is not covered with soil before the overburden, the top is exposed to the open air and the bottom is in contact with the earth, often causing a circumferential fracture. The fracture site is mostly close to the rigid joint and is severe in the spring and autumn. After field analysis, it was mainly caused by the temperature change of the air medium and the uneven humidity around the pipe. The temperature difference between day and night in the northwestern region is as high as 35°C at noon in the early fall season and drops to around 5°C at night in the open air. According to this temperature calculation, the temperature stress can reach 72.9 kg/cm~2, and the ultimate tensile strength of the asbestos cement pressure pipe is only