PE排污管道抗渗的措施

　有研究测定表明：新钢筋混凝土管地下水渗入量为210ｍ３／（ｋｍ・ｄ），占这些管道服务城区的城市污水量的19.4％。地下水水位高的城市排水管道的地下水渗入量很大，钢筋混凝土排水新管的管底以上地下水水位愈高，则排水管的地下水渗入量愈大。另外，随着管道使用时间的延长，由于多种损坏因素会导致管口开裂甚至管道或附属构筑物破坏，其渗入量必将大幅度升高。国外24座城市曾对管径为150~980ｍｍ陈旧排水管道进行过实测，地下水渗入量为4.2～3100ｍ３／（ｋｍ・ｄ）。地下水渗入排水管道， 会使输送、提升及处理的污水量增加，造成排水工程的投资和运行费都升高。因此，在经济可行的条件下，应尽可能降低排水管道的地下水渗入量。

管材质量的控制

　在管材的选取上，所有管材及其配件均须符合设计图纸及国家规定的产品材质需求。要求管材的出厂产品合格证书及有关资料齐全，并经检验合格后方可使用。在管道运输前和运到现场后，应按标准对管道逐一进行验收。要检查管道和管件的内表面、外表面及接口处，质量应符合要求，不应有任何损坏迹象。橡胶圈外观不应有气泡、裂缝、皱皮和变形等现象，存放时应避免与氯仿类和芳香族类溶剂接触。发现有质量问题的管道和管件应作退货处理。管道接口防渗漏目前，钢筋混凝土管和塑料管均可采用柔性接口。减少柔性接口管道的渗漏量可从接口橡胶圈的选用和橡胶条的应用以及提高橡胶圈的抗渗密闭质量等方面考虑。

橡胶圈的选用

　目前，管道常用的橡胶圈有滚动橡胶圈和滑动橡胶圈两种。 滚动橡胶圈常用的有截面为Ｏ形的橡胶圈。但其安装时在插口端易滚动，容易形成扭曲，影响接口的密封性能。 滑动橡胶圈常用的有截面类似于三角形的楔形橡胶圈。滑动橡胶圈的制造工艺较为复杂，价格也较高，在实际应用中有时因弹性不足，密封效果欠佳。但总体来看，滑动橡胶圈的使用效果优于滚动橡胶圈，应优先选用。

橡胶条的应用

　橡胶条在遇水后体积会膨胀，较一般的橡胶圈可接触到混凝土管接口处更多的不规则表面及空隙，防渗漏能力较强。但是价格达一般橡胶圈的两倍以上。另外，在遇热抗老化、抗伸强度、 脆性温度等方面与常规的橡胶止水带相比，性能上有一定差距。防止因管道基础导致管道损坏。

常用的PE排污管（中空壁缠绕管）

管道基础损坏的原因

　由于地基原因导致管道受力而损坏，造成管道渗水的情况主要有以下几种。

　　1）当地基的抗剪强度不足以支撑上部结构的自重 及附加荷载时，地基就会产生局部或整体剪切破坏，从而影响上部管道。

　　2）当地基由于上部结构的自重及附加荷载作用而 产生过大的压缩变形时，特别是超过管道所能允许的不均匀沉降时，则会引起管道过量下沉，接口开裂，影响管道的正常使用。

　　3）地震造成的地基土震陷以及地面车辆的振动和 爆破等动力荷载可能引起地基土失稳。

　　4）地基渗漏量或水力比降超过容许值时，会发生 水量损失或因潜蚀和管涌而可能导致管道破坏

　　市政排污管道工程设计是一个实践经验与能动性相结合的过程。在满足规范要求、注意设计控制要点的同时，根据实际情况，因地制宜、因时制宜，力求减少管道的渗漏水问题，尽量做到既质量优良，又经济合理、施工方便。

Studies and measurements have shown that the groundwater infiltration rate of new reinforced concrete pipes is 210m3/(km·d), accounting for 19.4% of the urban sewage volume served by these pipes. Urban drainage pipes with high groundwater levels have a large amount of groundwater infiltration. The higher the groundwater level above the bottom of the new reinforced concrete drainage pipe, the greater the amount of groundwater infiltration into the drainage pipe. In addition, with the extension of the pipeline's use time, due to a variety of damage factors will cause the nozzle to crack and even the pipeline or ancillary structures will be destroyed, and the amount of infiltration will inevitably increase. 24 foreign cities have conducted actual measurements on old drainage pipes with a diameter of 150-980mm, and the groundwater infiltration rate is 4.2-3100m3/(km·d). The infiltration of groundwater into the drainage pipeline will increase the amount of sewage that is transported, lifted and treated, resulting in an increase in the investment and operating costs of the drainage project. Therefore, under economically feasible conditions, the amount of groundwater infiltration into drainage pipes should be reduced as much as possible.

Control of pipe quality

　In the selection of pipes, all pipes and their accessories must meet the design drawings and the product material requirements specified by the country. It is required that the factory product qualification certificate and related materials of the pipe are complete, and can be used only after passing the inspection. Before the pipeline is transported and after it is transported to the site, the pipelines should be checked and accepted one by one according to the standards. To inspect the inner surface, outer surface and joints of pipes and pipe fittings, the quality should meet the requirements, and there should be no signs of damage. The appearance of the rubber ring should not have bubbles, cracks, wrinkles and deformation, etc., and avoid contact with chloroform and aromatic solvents during storage. Pipes and fittings found to have quality problems should be returned. Anti-leakage of pipe joints At present, both reinforced concrete pipes and plastic pipes can adopt flexible joints. Reducing the leakage of the flexible interface pipeline can be considered from the selection of the interface rubber ring, the application of the rubber strip, and the improvement of the impermeable sealing quality of the rubber ring.

Selection of rubber ring

　At present, there are two types of rubber rings commonly used in pipelines: rolling rubber rings and sliding rubber rings. Commonly used rolling rubber rings are rubber rings with an O-shaped cross-section. However, it is easy to roll at the socket end when it is installed, and it is easy to be twisted, which affects the sealing performance of the interface. A wedge-shaped rubber ring with a cross section similar to a triangle is commonly used for sliding rubber rings. The manufacturing process of the sliding rubber ring is more complicated and the price is higher. In practical applications, sometimes due to insufficient elasticity, the sealing effect is not good. But overall, the use effect of sliding rubber ring is better than rolling rubber ring, it should be preferred.

Application of rubber strip

　The volume of the rubber strip will expand when it meets water. Compared with the ordinary rubber ring, it can touch more irregular surfaces and gaps at the interface of the concrete pipe, and it has a strong anti-leakage ability. But the price is more than twice that of the general rubber ring. In addition, there is a certain gap in performance compared with conventional rubber waterstops in terms of heat aging resistance, tensile strength, and brittleness temperature. Prevent damage to the pipeline due to the foundation of the pipeline.

Commonly used PE sewage pipe (hollow wall winding pipe)

Causes of damage to the pipe foundation

　Because of the foundation, the pipeline is damaged due to the force, and the pipeline seepage is mainly caused by the following situations.

　　1) When the shear strength of the foundation is insufficient to support the weight of the superstructure and additional loads, the foundation will have partial or overall shear failure, which will affect the upper pipeline.

2) When the ground foundation produces excessive compression deformation due to the self-weight of the superstructure and the additional load, especially when the uneven settlement exceeds the allowable uneven settlement of the pipeline, it will cause excessive sinking of the pipeline, cracking of the interface, and affect the normality of the pipeline use.

　　3) Foundation soil subsidence caused by earthquakes, ground vehicle vibration and blasting and other dynamic loads may cause foundation soil instability.

　　4) When the foundation leakage or hydraulic gradient exceeds the allowable value, water loss or pipeline damage may occur due to erosion and piping

　　 Municipal sewage pipeline engineering design is a process that combines practical experience and initiative. While meeting the specification requirements and paying attention to the design control points, according to the actual situation, the measures should be adapted to local conditions and time conditions, and strive to reduce the problem of water leakage in the pipeline, and try to achieve both high quality, economic and reasonable, and convenient construction.