一、前言热力管道地下敷设,多年来一直沿用砖地沟。这种地沟,挖填土方量大,各道工序多为手工操作,劳动强度大,施工速度慢,而且常常要受不良气候的影响,很不适应城市建设高速度发展的需要。极需改变这种落后的施工面貌。在1977年修建前三门热力管道和1978年修建第二热电厂北干线热力管道施工中,对砖沟进行了改革试验。试用了工厂预制、现场装配的钢筋混凝土拱架。实践证明这种结构能 I. Preface The underground heating of thermal pipelines has been used for many years. This type of trench has a large amount of excavation and filling, and each of the processes is mostly manual operation, and the labor intensity is large, the construction speed is slow, and it is often affected by bad weather, and it is not suitable for the needs of high-speed urban development. It is extremely necessary to change this backward construction appearance. In the construction of the first three thermal power pipelines in 1977 and the construction of the second pipeline thermal power pipeline in the second thermal power plant in 1978, the brick trench was reformed. A prefabricated, on-site assembled reinforced concrete arch was commissioned. Practice has proved that this structure can