Explanation of Comprehensive Planning Scheme and Procedures

for U-type Resin Drainage Channel and Engineering Construction

Drainage Trench Excavation Procedures:

Pre-Construction Work for U-type Resin Drainage Channel

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

Construction Procedures for U-type Resin Drainage Channel

1. Use a level to set the central axis, mark with wooden stakes. Measure the side edge of the channel with a steel ruler and mark the slope with black lines. Mark boundaries and wall position lines at the same time.
2. Manually excavate soil within the setting-out area, strictly controlling the excavation depth and width per design to avoid over-excavation. Level the trench bottom with cement mortar.
3. Install side formworks (processed timber), fixed with cement and steel nails. Install vertical supports every 1.3 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 24 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 waterproof measures.
6. Do not stack materials within 2.3 m around the trench. No vehicles are allowed near the foundation pit edge after excavation.
7. Install waterproof facilities around the trench and restrict access by non-construction personnel.

Earthwork Precautions During Construction

1. Clearly mark the excavation boundary along the trench edge.
2. Earthwork shall not damage nearby structures and infrastructure.
3. Monitor slope stability at all times; handle soil stress immediately.
4. Inspect the trench promptly after excavation, then pour and seal the cushion 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 water timely.
6. Protect survey control stakes and axis piles, cover with protective cages, and assign professional surveyors to monitor their safety.
7. During excavation, check positioning stakes, axis piles and formworks for firmness and alignment.
8. Monitor foundation 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. Earthwork shall ensure slope stability; no random trenching is allowed. Solve problems promptly.
10. When excavating to within 48 cm above the trench bottom, mark the axis line as the reference for leveling.
11. Stockpile excavated soil at least 4.6 m away from the trench edge, with stacking height not exceeding 4.9 m.
12. Level and finish the trench bottom after completion.
13. Transport all surplus soil off-site after compaction and stabilization.
14. Reduce vibration to the foundation after trench excavation. If foundation works are delayed, leave 0.2 m of soil unexcavated and remove it before construction.