The construction process of the plastic inspection well was mentioned in the previous article, which can be referred to: the specific process of the construction process of the plastic inspection well. After understanding the process, we need to pay attention to some details, otherwise the project progress may be slowed down. What are the precautions for the construction process of the plastic manhole?
1、 Pit excavation
The excavation of well pit shall be carried out at the same time as the excavation of pipe trench. During excavation, the main pipe of the well bottom shall be on the same axis with the pipe in the pipe trench. Pit excavation must ensure safe construction, and slope excavation or support measures shall be taken according to geological conditions. The width of the pit construction working face outside the inspection well shall meet the design and construction requirements. During pit excavation, the over excavation of foundation soil shall not be disturbed. If the foundation soil is disturbed, remedial measures shall be taken according to the current national standard Code for Construction and Acceptance of Water Supply and Sewerage Pipeline Engineering (GB 50268) and the soil quality of the foundation soil.
When the groundwater level is higher than the bottom of the excavated well, the groundwater shall be lowered to 300mm below the lowest point of the well during construction., After the installation and connection of the inspection well, the dewatering can be stopped only after the backfilling reaches the height that meets the anti floating stability of the inspection well. If the inspection well is not backfilled after installation, it shall be reworked in case of displacement, floating or pulling out once it is flooded. Bricks, stones and other hard objects at the bottom of the well shall be removed. The well pit shall not be soaked in water. If the well pit is soaked in water during construction, the water shall be drained first, then the soaked soil layer shall be removed, sand gravel or medium coarse sand shall be replaced, and the next process shall be carried out after the compaction meets the design requirements.
During pit excavation, temporary soil piling or other loads shall not affect the stability of the pit. The height of soil piling and its distance from the pit edge shall be subject to relevant construction specifications.
2、 Inspection well construction foundation
The inspection well must be installed on the foundation soil layer that meets the design requirements, or the well pit must be excavated and compacted to a dense foundation. The foundation of the inspection well shall be constructed according to the design requirements. If there are no clear requirements in the design, the sand gravel cushion foundation is generally used. For general soil, a layer of 100mm thick coarse sand foundation can be laid on the base. The cushion shall be paved according to the width of the trench, leveled and compacted.
For soft soil foundation, sand gravel shall be used to replace soft soil, and its thickness shall not be less than 200mm. It can also be laid in two layers. The lower layer is gravel with a particle size of 5mm~40mm and a thickness of 100mm~150mm. The upper layer is paved with medium coarse sand with a thickness of no less than 50mm. The compaction coefficient of sand gravel cushion should not be less than 0.95. When the inspection well is located in the collapsible loess area, the base should be paved with 100 mm to 150 mm of 37% lime, and then 100 mm medium coarse sand cushion. For the foundation laying method, please refer to the inspection well foundation drawing of relevant standards. More about Please pay attention to the official website of Hainan Plastic Industry Co., Ltd.
