Explanation of Resin U-type Drain Channel and Detailed Safe Construction Methods and Procedures

1. General Construction Flow

2. Sequence of Drainage Outlet Construction

Pre-Construction Preparation for Resin U-type Drain Channel

1. Construction shall not start with random excavation. Geological investigation must be carried out to check geological conditions and parameters, and confirm suitable locations for drain channel construction.
2. Before trench construction, review and verify the setting-out lines.
3. Before excavation, inspect underground structures and existing drainage systems on site. Complete site drainage works to prevent groundwater from flowing into the trench and affecting construction. This step is mandatory.
4. Organize construction personnel and machinery, and complete all construction organization and technical disclosures to ensure smooth completion of the works.
5. Machinery for foundation excavation and backfilling: stationary and crawler excavators.

Construction Procedures of Resin U-type Drain Channel

1. Use a theodolite to set the central axis, mark with steel nails. Measure the inner edge of the drain channel with a caliper and mark the slope with lines. Mark boundaries and wall position lines at the same time.
2. Manually excavate soil within the setting-out area, strictly controlling the construction depth and size per design to avoid deviation. Level the trench bottom with concrete.
3. Install side formworks (processed timber), fixed with concrete nails. Install vertical supports every 1.4 m to prevent formwork displacement. Apply release agent on the contact surface between formwork and concrete.
4. Cover and cure the concrete with water within 18 hours after pouring. Under normal temperature, water at least twice a day; curing period shall not be less than 7 days.
5. Monitor weather conditions during construction, avoid working in rain, and take rainproof and moisture-proof measures.
6. Do not stack materials within 2.5 m around the trench. No vehicles are allowed near the foundation pit edge after excavation.
7. Install moisture-proof facilities around the trench and restrict access by non-construction personnel.

Foundation Excavation Standards During Construction

1. Clearly mark the excavation control line along the trench edge.
2. Manual foundation excavation shall not damage nearby structures and underground pipelines.
3. Monitor slope stability at all times; handle soil instability immediately.
4. Inspect the trench promptly after excavation, then pour concrete cushion and seal it before proceeding to the next process.
5. Reserve a working space of at least 550 mm between the trench bottom and the foundation/cushion edge. Install drainage ditches and catch wells on one side to drain rainwater timely.
6. Protect survey control stakes and axis piles, cover with steel cages, and assign professional surveyors to monitor their safety.
7. During construction, check positioning stakes, axis piles and formworks for firmness and alignment.
8. Monitor soil conditions and groundwater changes and keep records. If the foundation soil does not meet design requirements, coordinate with the design department for solutions.
9. Foundation excavation shall ensure subgrade stability; no random trenching is allowed. Solve problems promptly.
10. When excavating to about 45 cm above the trench bottom, mark the horizontal line as the reference for leveling.
11. Stockpile excavated soil at least 5 m away from the trench edge, with stacking height not exceeding 4.4 m.
12. Level and finish the trench bottom after completion.
13. Transport all surplus soil after compaction and stabilization.
14. Reduce vibration to the foundation after trench excavation. If frame construction is delayed, leave 0.5 m of soil unexcavated and remove it before construction.