国内外标准中非开挖管道土压力计算模型对比研究

Comparison of calculation models of soil pressure for trenchless pipe in the standards at home and abroad

通过对我国《给水排水工程管道结构设计规范》(GB 50332-2002)、北美《大型水平定向钻进穿越障碍物(包括河流)铺设聚乙烯管道或导管的技术指南》(ASTM F1962-11)和欧洲《供气系统最大工作压力大于16巴的管道功能要求》(BS EN 1594-2009)三个标准中非开挖施工管道土压力计算模型进行对比分析,发现GB 50332-2002采用的不开槽土压力系数并不是土拱理论定义的真实土拱系数,且计算模型较为简单,忽略了土体的粘聚力,没有充分考虑土体内摩擦角对土拱系数的影响,导致土拱系数以及管顶土压力受到土体性质的影响较小。对于不可压缩的土体,当土体内摩擦角小于15°时,GB 50332-2002计算的土拱系数偏小;而对于可压缩性土体,GB 50332-2002计算得到的土拱系数远小于其他两种标准。

Soil pressure calculation models for trenchless pipe based on Terzaghi Soil Arching Theory have been defined in Structural design code for pipelines of water supply and wastewater engineering（GB50332-2002）in China,Standard guide for use of maxi-horizontal directional drilling for placement of polyethylene pipe or conduit under obstacles including river crossings（ASTM F1962-11）in North America,and Gas supply systems-pipelines for maximum operating pressure over 16 bar-Functional requirements（BS EN 1594-2009）in Europe.The Comparison was made to investigate the difference between GB 50332-2002 and other two standards.It was found that the soil pressure factor in GB 50332-2002 was not the real arching factor defined in soil arching theory.The calculation model in GB 50332-2002 ignored the cohesion and compressibility of the soil,and did not fully consider the effect of the internal friction angle of soils,which led to a small impact of the soil properties on the arching factor.For uncompressible soil,when the soil interal friction angle less than 15°,the arching factor calculated by GB 50332-2002 was relatively small;furthermore,for compressible soil,the arching factor calculated by GB 50332-2002 was far less than that calculated by the other two standards.