An introduction to the full-rotation (SUPERTOP method) construction method, very detailed!

The full-rotation and full-casing construction method is called the SUPERTOP method in Japan. Steel casing is used to protect the wall during the hole formation process. It has the characteristics of good pile quality, no mud pollution, green ring, and reduced concrete filling coefficient. It can effectively solve the problems of hole collapse, neck shrinkage, and high filling coefficient that occur when ordinary methods are used for cast-in-place pile construction in urban high fill and karst landforms.

Rock drilling

The full-rotation drill has strong torque, penetration force and cutter head, which can complete the construction tasks in hard rock formations. The rock hardness that can be drilled can reach: uniaxial compressive strength 150-200MPa; due to its perfect cutting performance, it has been widely used in cutting: concrete blocks, high-strength bolts, H piles, steel pipe piles and other clearing construction.

Cast-in-place pile construction through caves

Fully rotary drilling rigs have unparalleled advantages in cave construction over other construction processes: they do not require backfilling of rocks or additional casing. With its own good vertical adjustment performance, automatic control performance of drilling speed, drilling pressure, and torque, it can easily complete the drilling task through the cave. When pouring concrete in the cave, it is done in the casing, and the concrete with the addition of the quick-setting agent is not easy to lose. And because the drilling rig has a strong pulling force, it can also delay pulling. Therefore, it can well complete the construction task of cast-in-place piles in the cave.

High vertical accuracy

It can achieve a vertical accuracy of 1/500 (rotary drilling rigs can reach 1/100), which is one of the pile foundation processes with the highest vertical accuracy in the world.

1. Full-revolving cast-in-place pile construction machinery configuration

Main equipment and components:

1. Full-revolving drilling rig: hole forming

2. Steel casing: wall protection

3. Power station: provides power for the full-revolving main engine

4. Reaction fork: provides reaction force to prevent the main engine from shifting during full-revolving rotation

5. Operation room: operation platform, personnel operation place

Auxiliary equipment:

1. Rotary drilling rig or grabbing: soil extraction, rock entry, hole cleaning

2. Pipe jacking machine: pipe extraction, full rotation to form a flow operation

3. Crawler crane: lifting the main machine, power station, reaction fork, etc.; providing support for the reaction fork; lifting steel cage, concrete conduit, grabbing soil, etc.;

4. Excavator: leveling the site, clearing the slag, etc.

二. Full rotation steel casing cast-in-place pile construction process

1. Construction preparation

The main work of construction preparation is to level the site. Since the drilling rig is large and has many related auxiliary equipment, there are certain requirements for access channels and work platforms. Therefore, construction preparation needs to consider the construction channels and work planes required for operations such as pile foundation steel cage processing and production, slag transportation, steel cage lifting and installation, and pile foundation concrete pouring.

2. Measurement and layout

First, carefully review the coordinates, elevation and other relevant data provided by the design drawings. After confirming that they are correct, use the total station to lay out the pile position. After the pile center is laid out, draw a cross line along the pile center to 1.5m away and make a pile protection mark.

3. Full-revolving main engine in place

After the point is released, hoist the full-revolving chassis, and the center of the chassis should coincide with the center of the pile. Then hoist the main engine, install it on the chassis, and finally install the reaction fork.

4. Hoist and install the steel casing

After the main engine is in place, hoist and install the steel casing.

5. Measure and adjust verticality

After the rotary drilling machine is in place, perform rotary drilling, and press down the casing while rotating to drive the casing, so that the casing can be quickly drilled into the formation. When drilling the steel casing, use a plumb line to adjust the verticality of the casing in the XY directions.

6. Casing drilling and soil extraction

While the casing is drilled into the ground, a crane is used to release a grab bucket along the inner wall of the casing to the bottom of the hole to extract soil by grabbing or using a rotary drilling rig to extract soil.

7. Fabrication and installation of steel cage

After drilling to the designed elevation, clean the hole. After passing the inspection and acceptance by the land survey, supervision and Party A, install the steel cage.

8. Concrete pouring, casing extraction, and pile pouring

After the steel cage is installed, pour concrete. After the concrete is poured to a certain height, pull out the casing. The casing can be pulled out using a pipe jacking machine or a full-rotation main machine.

三、. Advantages of full-rotation construction:

1 It can solve the pile construction in special sites, special working conditions and complex strata, with no noise, no vibration and high safety performance;

2 Does not use mud, the working surface is clean, can avoid the possibility of mud entering the concrete, which is conducive to improving the bond strength of concrete to the steel bars; prevents soil backflow, does not scratch the hole wall when lifting the drill and lowering the steel cage, and has less drilling debris;

3 When constructing the drilling rig, it can intuitively judge the stratum and rock characteristics;

4 The drilling speed is fast, which can reach about 14m/h for general soil layers;

5 The drilling depth is large, and the maximum depth can reach about 80m according to the soil layer conditions;

6 The verticality of the hole is easy to grasp, and the verticality can be accurate to 1/500;

7 It is not easy to produce hole collapse, the hole quality is high, the bottom is clean, the speed is fast, and the sediment can be cleared to about 30mm;

8 The hole diameter is standard and the filling coefficient is small. Compared with other hole-forming methods, a large amount of concrete can be saved.

The rotary drilling hole collapsed seriously due to the backfill soil layer being too thick and containing large rocks.

Hole-forming effect of full casing

Fully rotary drilling rigs are not only used for pile foundation construction in various complex strata such as quicksand, karst landforms, and super-high backfill, but can also be used for bite pile construction, subway steel columns, and pile removal.