一、市政工程局技委会管道学组与市政设计院排水空部分同志一次座谈意见认为市政局现行标准是在管径φ1800以下的重力流管道、顶距50m左右这一特定条件下制订出来的。现在随着工艺的改革,顶管已适用于各种施工条件下各种功能管道一次顶距已能达到70～80m左右,个别有超过100m的。另一方面,自φ880开始,各种不同管径统一使用+1, I. The Municipal Engineering Bureau Technical Committee Pipeline Group and the Municipal Design Institute Drainage and Air Comrades held a symposium that the current standards of the Urban Council were developed under the specific conditions of a gravity flow pipeline with a diameter of φ1800 or less and a roof distance of about 50m. . Now with the reform of the process, the pipe jacking has been applied to a variety of construction conditions under a variety of functional pipe can reach a top distance of 70 ~ 80m, individual more than 100m. On the other hand, since φ880, +1 has been used for all different diameters.