Anhui Suzhou – SJL-120 – MJS Method Construction

Location (Province): Anhui  

Location (City): Suzhou  

Drill Model: SJL-120 Rotary Jet Drill Rig  

Drill Tooling: Ammann 142 series multi-hole drill bit, drill pipe, swivel  

Process Type: Rotary jet grouting cut-off (water stop)  

Construction Method: MJS Method  

Stratum Conditions: 1-6m backfill soil; 6-8m silt; 8-26m aged clay  

Construction Angle (°): 90  

Pile Diameter (mm): 2000  

Pile Depth (m): 25

Construction Method

Equipment Configuration:

① One pilot drill rig

② One SJL-120 rotary jet drill rig (equipped with 142 series multi-hole drill pipe, multi-hole drill bit, and multi-hole 

swivel)

③ One 13 bar / 10 m³ air compressor

④ One 230 high-pressure pump

⑤ Two 90E high-pressure pumps (pre-cutting is required due to clay strata)

⑥ Several 19 mm ID 4-layer high-pressure hoses

⑦ One slurry return pump

⑧ One cement silo set (the SJL-120 drill rig has its own lifting system, so no crane is required)

1. Level the site and mark each pile position. First, use the pilot drill rig to drill the pilot holes.

2. After pilot drilling, move the pilot rig away and level the site again to ensure stable operation of the SJL-120 

drill rig (use base plates if the ground is uneven). Align the SJL-120 drill rig with the pile center as required and 

adjust the level using the outriggers.

3. Lift the drill bit into the power head and clamp it. Install one section of 142 multi-hole drill pipe and the 142 

multi-hole swivel. Connect all hoses and conduct a pressure test. After testing, seal the nozzles and slurry return 

ports with tape (to prevent blockage during lowering).

4. Remove the swivel together with the attached drill pipe section. Then begin adding drill pipe sections one by

 one. When connecting each section, ensure that the sealing rings and sensor cable connectors are properly fitted. 

Finally, reinstall the swivel with its attached drill pipe section.

5. Start the air compressor, high-pressure grouting pump, slurry return pump, and pre-cutting water pump from

 the backup system. (First use clean water to cut the pile bottom with the high-pressure grouting pump for about

 20 minutes, then begin injecting cement slurry.) Operating parameters:

- Grouting pressure: 40 MPa

- Pre-cutting water pressure: 25 MPa

- Air pressure: 1 MPa

- Water pressure: 10 MPa

- Rotation speed: 4 r/min

- Lifting speed: 25 mm/min

Notes:

① During construction, continuously monitor changes in rotation pressure (to prevent pipe sticking) and the internal

 ground pressure.

   - Poor slurry return + excessively high ground pressure → ground disturbance

   - Excessive slurry return + too low ground pressure → slurry evacuation, hole collapse, and pipe sticking

② If pipe sticking occurs, shut down the equipment and develop a plan to retrieve the drill tools. (Avoid using the drill

 rig’s high-torque oscillation for extended periods to resolve sticking, as the bolted connections at the drill pipe joints 

may experience mechanical fatigue and breakage.)