1. Permafrost foundations may be constructed using dry bored piles, excavated cast-in-place piles, etc., or driven cast-in-place piles, precast piles, etc.

2. During pile foundation construction, when the frozen soil layer exceeds 500 mm in thickness, the frozen soil layer should preferably be pre-bored with a drilling machine, and the pre-bored diameter should not exceed the pile diameter by more than 20 mm.

3. The drill bit of the drilling machine should preferably be a conical bit with welded alloy blades. When drilling into frozen soil, the pressure of the drill rod on the soil layer should be increased, and swinging and deviation should be prevented. The drilled pile holes should be covered and protected in a timely manner.

4. During vibratory driven casing hole formation, a construction sequence ensuring the concrete quality of adjacent piles should be established. When extracting the casing, cement slurry and mud on the casing wall should be removed promptly. When there is an interruption in hole formation, the pile casing should preferably be embedded in the pile hole for insulation.

5. The concrete construction of cast-in-place piles shall comply with the following provisions:

(1) The heating, mixing, transportation, and pouring of concrete materials shall be carried out in accordance with the relevant provisions of Chapter 6 of this specification; the concrete pouring temperature shall be determined by thermal calculation and shall not be lower than 5°C;

(2) The curing of pile concrete within the frost depth range of the foundation soil and above ground shall be carried out in accordance with the relevant provisions of Chapter 6 of this specification;

(3) When constructing on frost-heaving foundation soil, protective measures shall be taken to prevent or reduce tangential frost-heaving forces between the pile and the frozen soil.

6. Precast pile construction shall comply with the following provisions:

 (1) Before construction, the pile surface shall be kept dry and clean;

 (2) Before lifting, anti-slip measures shall be taken for the wire rope slings and the clamps of the pile driver.

 (3) Pile driving shall be carried out continuously; after construction is completed, insulation materials shall be used to cover the piles for insulation.

 (4) Pile splicing may use welding or mechanical connections; welding and anti-corrosion requirements shall comply with the relevant provisions of Chapter 9 of this specification;

7. Before static load testing of pile foundations, the frozen soil around the test piles shall be thawed or excavated. During the test, the surface soil around the test piles and the anchor pile crossbeam supports shall be insulated.