Construction Method of PE Pipe in Municipal Water Supply and Drainage Engineering

PE pipes in municipal water supply and drainage engineering are mainly divided into two types of construction methods: slotted laying and non excavation. Today, PE pipe manufacturers mainly elaborate on the slotted laying construction method.

(1) Firstly, during construction, attention should be paid to the specifications of pipeline laying according to relevant regulations, and inspections should be conducted according to product standards to remove pipes that do not meet the standards. If the pipeline is laid under the roadway, the thickness of the soil covering the top of the pipeline should not be less than 0.7 meters. If it is necessary to cross obstacles, protective sleeves made of steel bars or other materials should be installed. When laying pipelines, they should be constructed in a straight line. If flexible interface polyline laying is required, the longitudinal axis angle of the connected pipelines should not exceed 2 °. When the burial depth of the pipeline is lower than the foundation bottom of the building, the pipeline should not be laid within the range of the foundation diffusion angle compression zone under the building foundation. When the groundwater level is higher than the elevation of the excavated trench bottom in the area, measures should be taken to lower the groundwater level during construction to prevent trench instability. During the entire installation and backfilling process, attention should be paid to ensuring that there is no water accumulation at the bottom of the trench or that the trench is frozen.

(2) PE pipes with different stiffness should be selected according to the external pressure conditions.

(3) When excavating trenches, the bottom width of the PE pipeline trench should be reasonably determined first, in accordance with construction regulations, in order to facilitate manual operations. During the construction process, over excavation of trenches is not allowed. If over excavation is accidentally carried out, natural graded sand and gravel materials should be used for landfill. The particle size of the buried sand and gravel should be between 10mm-15mm, or the maximum particle size should be less than 40mm.

(4) The pipeline foundation adopts a sand cushion layer foundation, and grooves should be reserved at the interface for interface operation. After the interface construction is completed, sand should be used for burial. For general soil sections, only a 0.1M thick sand cushion layer needs to be laid on the base. If it is a soft soil foundation and the bottom of the trench is located below the groundwater level, it is advisable to lay a layer of gravel foundation with a thickness of not less than 500px.

(5) During the installation of the lower pipe, strict inspections should be conducted on the width and depth of the slotted groove, the elevation of the foundation surface, and the inspection well to ensure that the work items meet the construction requirements and regulations before proceeding to the next step, in order to improve the construction quality.

(6) After the inspection is completed, the next step is to connect and install the PE pipeline. It is advisable to use non-metallic rope chutes for manual installation to ensure that the pipeline is smoothly placed on a gravel foundation. The installation sequence of socket pipes should generally be in the direction of water flow, with the socket facing the opposite direction of water flow, and installed in sequence from low to high. When performing the interface process, the two sides of the mouth should be cleaned first and then coated with lubricating oil. After coating, align with the centerline and wait for connection. The connection between the pipeline and the inspection well can be made using an intermediate layer method. The pipeline connecting the two parts is pre coated with a plastic adhesive and coarse sand that can bond well with the pipe material as an intermediate layer, and then connected with 1:2.5 cement. Then, the mortar is built into the inspection well wall to make the joint between the well and the pipe dense. The bottom groove of the well is smoothly connected to the inner wall of the pipe, and the pipe mouth is flush with the inner wall of the well.

(7) After the installation of PE pipes is completed, strict inspection should be carried out. If the inspection is qualified, trench backfilling can begin. During trench backfilling, the area from the bottom of the pipe to the top of the pipe within 1750px must be manually backfilled. Mechanical backfilling can only be used for areas above 1750px. When backfilling, it is necessary to pay attention to the absence of debris in the trench. In addition, the compaction degree of backfill should not be less than 95% in the chest area, not less than 80% in areas above 500mm from the top of the pipe, and not less than 90% in other areas. Attention should also be paid to the selection of compaction equipment to avoid damage to the pipeline structure during construction.