【Construction Case】SJL-120 rotary jet drilling rig

Stratigraphic Situation

Location (Province): Anhui

Location (City): Suzhou

Drilling rig model: SJL-120 rotary spray drilling rig

Drilling tool configuration: Anman 142 series multi-hole drill bit, drill pipe, splitter

Process Type: Hydrospray stop

Construction process: MJS method

Stratigraphic conditions: 1-6 m backfill.

6-8 m chalk sand.

8-26m old clay

Construction angle(°):90

Pile diameter(mm): 2000

Pile depth(m):25

Construction techniques

Configuration:

①one pilot hole drilling rig

②One SJL-120 rotary spray drilling rig (with 142 multi-hole drill pipe, 142 multi-hole drill bit, 142 multi-hole splitter)

③One air compressor 13kg 10 cubic meters

④One 230 high-pressure pump

⑤Two 90E high-pressure pumps (pre-cutting must be used because the stratum is clay)

⑥Several 19 diameter 4-layer high-pressure pipes

⑦One counter slurry water pump

⑧a set of cement tank (SJL-120 rotary drilling rig comes with a crane, so there is no need to prepare a crane)

Backstage site configuration diagram

1、Level the site, determine the position of each pile, and lead the holes with the lead hole drilling rig first.

2、Remove the pilot drilling rig after citing the holes, level the site again to ensure that the SJL-120 drilling rig works smoothly (uneven site requires paving substrate), align the SJL-120 drilling rig with the center of the pile as required, and level it with the outriggers.

3、hoist the drill head and install it into the power head clamp, install a section of 142 multi-hole drill pipe and 142 multi-hole diverter, then connect all pipelines for pressure testing, and seal the nozzle and slurry return port with tape after the test is completed (to prevent blockage during the down drilling process).

4、Then remove the diverter with a section of drill pipe and start to connect the drill pipe in turn. Pay attention to each joint seal and sensor wire connector when connecting the drill pipe, and finally connect the diverter with one section of drill pipe.

5、In the background, turn on the air compressor, high pressure pump grouting pump, back slurry pump and pre-cutting pump (high pressure grouting pump first cut the bottom of the pile with water, and then start to inject water slurry for about 20 minutes). At this time slurry pressure 40 MPa, pre-cutting water 25 MPa, air pressure 1 MPa, water pressure 10 MPa, rotation speed 4r/min, lifting speed 25mm/min.

Note: 

① During the construction, it is necessary to pay attention to the change of rotary pressure (to prevent holding the drill) and the value of the internal ground pressure (too high internal ground pressure due to bad counterpulping and too low internal ground pressure due to collapse of the hole after pumping the pulp out and holding the drill).

② If the drill pipe holding situation should be shut down the machine to develop a plan to salvage the drilling tool (try to avoid the use of high-torque swing of the rig to deal with the drill pipe links using bolt links, long time use of high-torque swing bolts are prone to mechanical fatigue resulting in fracture)

                                                                                    ——Anman rig sales and service: Lu Xinke