Drilling technology of rotary drilling rig?

The hole-forming technology of rotary drilling rig is very important, and full preparation is the premise, but the key is to do the best construction technology. Zhong Da Consulting Company will introduce the hole-forming technology of rotary drilling rig in detail.

1, gasket embedding

The embedded steel lining should be pre-drilled with a drill bit slightly larger than the diameter of the borehole. After drilling to the elevation position at the bottom of the casing, lift and bury the steel casing. The top of the liner shall be not less than 0.3m higher than the construction surface, and the outer side of the liner shall be coated with residual oil with a thickness of 10mm. After the steel casing is buried, the outer periphery of the casing is backfilled with coarse-grained soil, and the backfill is dense.

2. Pore formation

1) drilling

Rotary drilling rig is dry drilling. When drilling, the drill bit touches the ground first, and the hole is rotating. The self-weight and pressurization of the drill bit are used as drilling power. When the drill bit rotates, squeezes and fills with drilling slag, it is lifted out of the surface and loaded into the slag dump truck. At the same time, observe the situation in the monitoring hole. If the ground is underground or the groundwater level is greater than the drilling depth, dry hole drilling can be used without worrying about hole collapse. If there is groundwater distribution and the hole wall is unstable, the wall protection mud or stabilizing liquid can be injected to protect the wall. When drilling, the slag at the orifice should be removed in time so as not to hinder the drilling construction.

2) Borehole cleaning

After the hole reaches the design elevation, check the hole depth, hole diameter, hole wall and verticality, and take measures to deal with it if it is unqualified. The hole-forming inspection method depends on the aperture. When the hole is dry, directly measure it with measuring rope and hole gauge. According to the pile hole situation, determine the hole cleaning method. After the hole is dry, the virtual soil in the hole can be compacted with a heavy hammer. If there is groundwater in the hole, pumping and reverse circulation pumping can be used to clean the hole. Reasonable control of mud viscosity and sand content in wellbore purification process. Pile holes that pass the quality inspection shall be poured with concrete in time. When it is too late to pour concrete, the dry hole should be covered with iron plate in time.

3, reinforcing cage production and installation

Reinforcing cages are fabricated in sections in the workshop. Stiffening rib molding method is adopted. In order not to hinder the binding of spiral steel bars, the stiffening rib is located inside the main reinforcement. When making, the stiffening ring should be made according to the design size of the drawing, and the position of the main reinforcement should be marked. When welding, align the mark of any main reinforcement on the stiffening rib with the mark in the middle of the main reinforcement, straighten the stiffening rib, correct the verticality between the stiffening rib and the main reinforcement, and then spot weld. When one main reinforcement is welded with all stiffening ribs, one person is set at each end of the skeleton to rotate the skeleton, and the other main reinforcements are welded one by one according to the above method. Then carry the skeleton away, put it on the bracket, and coil the steel bar. Spiral reinforcement is arranged according to the design position, tied to the main reinforcement, and welded firmly. Finally, install and fix the sound tube. After the drilling reaches the preset drilling depth, lift the drill pipe, and measure the hole depth and virtual soil thickness with measuring rope (hammer) (the virtual soil thickness is equal to the difference between the drilling depth and the hole depth). Because of the heavy weight of steel skeleton, it is manufactured, transported and installed in sections during construction. After the reinforcement skeleton is made in the workshop, the reinforcement cage is installed with a truck crane. In the whole process, in order to ensure the quality requirements of the reinforcing cage, we must pay attention to the fact that the reinforcing cage cannot be deformed during transportation. When installing the reinforcing cage, use two-point lifting. After the reinforcing cage is vertical, check the verticality. After the skeleton enters the orifice, it should be righted and lowered slowly. It is forbidden to swing and collide with the hole wall. When lowering, the inner support should be removed, and it is forbidden to fall into the hole. When the first section skeleton is placed at the position of the last stiffening rib, it is placed in the I-beam, and the reinforcement is supported on the I-beam at the orifice, and then the second section skeleton is hoisted to align and weld it on the same vertical axis (or the reinforcement sleeve is used to speed up the progress and shorten the lowering time of the reinforcement cage). First, weld two joints in one direction, then lift them slightly to make the upper and lower reinforcing cages vertical under their own weight, and then weld all other joints. After the joint is welded, it shall be welded again. In this way, the skeleton is lowered to the design elevation and located in the center of the hole to complete the installation of the reinforcing cage.

4, concrete pouring

In-situ pouring of pile foundation concrete, whether there are dry holes or water heads in the holes, the construction method of underwater pouring concrete is adopted. The concrete is poured by direct conduit method, and the concrete is commercial concrete.

1) catheter

Construction adopts 273mm rigid conduit, which should be solid, smooth, straight and smooth, and the inner tube size of each conduit is consistent, with a deviation of not more than 2mm. Before and after the catheter is used for a certain period of time, conduct water tightness and pressure bearing tests to check whether the waterproof rubber pad is in good condition and whether there is aging phenomenon. After use, the catheter should be oiled and numbered to ensure no water leakage, no rupture and orderly use.

2) Cut the ball

Because the reinforcing cage is lowered for a long time, secondary hole cleaning should be carried out after the conduit is lowered to control the deposition thickness in the hole within 5cm. Precast concrete cylinder, 20cm long 15cm, sealed with rubber pad, placed on the top of the conduit, hung with iron wire, and the bottom of the conduit is about 50cm away from the bottom of the hole. Pump concrete. When the pump fills the hopper and storage hopper, cut the ball immediately to ensure that the buried pipe of the first batch of concrete pipes is greater than1m. During the pouring process, pump the overturned mud into the mud tank or other adjacent liners for standby at any time.

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