一、引言 发展城市集中供热其外部热网基本上还是沿用地沟敷设方式,它存在着结构庞大,占地多、施工困难、投资高、热损失大、易腐蚀、耐用年限短等弊病,特别是在老城区,街道窄小、交通繁忙、建筑物密集、地下管线纵横交错的地方,敷设大型管沟就更加困难。 目前,国内有些城市,采用热力管纲部分直埋敷设方式,如北京地区就采用了热压沥青珍珠岩保温管的直埋敷设方式,这种敷设方式具有货源充足,价格便宜的优点。其主要缺点是在运输或施工吊装过程中容易产生外保护壳裂纹,埋入地下,水汽通过裂纹 I. INTRODUCTION The development of urban district heating is basically based on the laying of trenches in the external heating network. It has many disadvantages such as huge structure, large area, difficult construction, high investment, large heat loss, corrosion, and short service life. In the old town, where there are narrow streets, heavy traffic, dense buildings, and criss-crossing underground pipelines, it is even more difficult to lay large trenches. At present, in some cities in China, heat pipes are used for direct burial. For example, in Beijing, hot embossed asphalt perlite insulation pipes are used for direct burial. This method has the advantages of adequate supply and low price. Its main disadvantage is that it is easy to produce cracks in the outer protective shell during transportation or construction lifting, buried underground, and water vapor passing through cracks.