Screw piles are mounted in several ways, which differ in the level of mechanization. It is manually tightened by a team of 3 - 4 workers, and the mechanical method involves the use of special mechanisms and units. The screw pile driving machine increases labor productivity by about 2 times. Automation is used if extended elements are placed at a great immersion depth or piles have an impressive cross-section.
How to tighten screw piles when building a foundation
Structural parts of the pile:
- The barrel, which has a guiding section with helical blades and an extension. The latter also has blade parts, but more often it consists of couplings and a barrel.
- Bearing screw blades.
- Pointed pile tip (foundry) with bearing helical wings.
When screwing, the screw elements pass through different soil layers and move slightly due to uneven soil. Tightening involves a slight inaccuracy of installation compared to driving or injection. There are hard particles in the ground, such as large roots or rocky stone inclusions, so sometimes the screw strut will get stuck.
Stopper means a situation where 3 - 5 people twisting the pile element can no longer bury it. The rod reaches a dense layer that cannot pass through, so screwing is stopped. If the immersion depth is insufficient, the pile is removed and screwed side by side on the marking line. It is not recommended to screw into the same passage.
An emphasis on a solid layer means that the pile has reached a stable soil layer, its bearing capacity will correspond to the design value.
What can be used, tools and equipment
The mechanical pile driver grips the trunk, holds it and slowly rolls the tip wings into the soil at a predetermined incline. More often, vertical rods are placed at an angle of 90 °, and the inclination (up to 45 °) is taken by calculation and additionally indicated in the drawing.
The equipment consists of working parts:
- basic platform for installing units on wheels or tracks;
- retractable hydrotechnical jacks (4 pcs.) for fixing the machine and adjusting the stop;
- hydraulic gripper;
- drive for twisting the pile and coordinating the angle of inclination;
- control panel.
The force of rotation is transmitted through the drive to the tip of the vertical rack, the blades begin to spin. The rod is immersed in the ground by turning the screws, overcomes the soil obstacle. The integrity of the tip at this stage of deepening matters, so the pointed structural element is made of a strong alloy and cast.
There is a danger of destruction or deformation of the welded paddle wings when hitting stones, but the hydraulics overcome the resistance. Screwing in does not destroy the soil layers, but compacts the soil around the trunk at a distance of 1 - 2.0 meters, depending on the cross-section of the vertical element.
How to screw piles with a motor drill
Marking and preparing the surface of the site before diving.The motor-drill allows you to install the screw rack strictly vertically, but the work takes place with the participation of two people. I choose the diameter of the auger auger so that it is less than the cross-section of the pile in order to get an effective grip and avoid skewing.
The first elements are installed in the corners of the foundation, while they note that they have reached a stable soil layer. The racks at the corners are immersed at the design mark, and the intermediate elements can be deepened less if the rack does not go further, and additional supports can be added along the marking line.
Features of working with a motor-drill:
- rocky and stony soils are drilled at low speeds, trying to raise large elements;
- when the vibration auger is jammed, use the reverse (reverse) stroke;
- the worker takes a stable position so that the jerk when stopping does not knock him down;
- the drill is taken out and cleaned from the ground every half hour of work;
- rocky seams pass with the installation of carbide blades on the auger.
The motor-drill effectively copes with any kind of soil, while paying attention to the design characteristics of the pile rods. Diameter, pitch of blades, angle of inclination are selected individually and depend on the load and physical properties of the soil layer.
Types of motor-drills and the installation process
A motor-drill is chosen depending on the category of soil, the device for twisting screw piles is classified according to the type of motor and power.
Mechanical lightweight units weigh 11 kg, one person copes with the work. The units differ in motor power up to 3.5 l / s. The hand-held unit is used only for drilling in soils of categories 1, 2 with low density indicators.
The automatic device with an increased engine capacity of up to 7 l / s requires a second person to operate when drilling tight rock. The unit weighs 30 kg, so 1 operator can work on light soils. Such units are also used in gentle conditions.
Two-block motor-drills contain a motor and a drilling section, which are located on a connecting rod. The power is 5 - 8 l / s, and the weight of the unit is at the level of 80 kg. The connecting rod dampens recoil when there is a lot of soil resistance, so one worker can handle it. Precision equipment maintains verticality without deviation.
Motor-drills based on hydraulics have a power of 11 - 15 l / s, they are used for lands of groups 2, 3. Manual rigs are easy to move around the construction site, one worker can drill, but it all depends on the strength of the soil. Domestic Iron installations are more often used, which the manufacturer supplies with a mechanical drive and hydraulics.
Tightening screw piles with a hole drill
Yamobur is an installation for screwing piles, which is taken if you need to screw many screw posts in a short period. For a shift, the team makes 30 piles using this unit.
The work consists of the following stages:
- placing a hydraulic rotator in the pile shaft and fixing it with a pin;
- alignment and installation of the vertical rod at the mounting point;
- screwing the rack into the ground.
Yamobur works without problems in difficult and cramped conditions. An obstacle in the form of coarse rocks does not stop the action of the drill, as does the installation of supports in water bodies or on watered coastal slopes. Yamobur allows you to mount screw elements at different times of the year and does not depend on the weather. Tightens piles reliably with permissible errors in accordance with regulatory documents.
The unit is used in summer cottages and courtyards due to its small dimensions.
Yamoburs are produced on the basis of a gasoline or electric motor. Includes a set of tips for different soil categories and tilt drilling. For the manufacture of the tip, they take durable metal with a special coating to increase the service life.
Features of screwing screw piles with a meat grinder
The meat grinder is a manual device that includes an electric or hydraulic transmission with a pile head attachment. A leverage scheme is used for fastening the tool and transmitting torque. The device got its name from the UMK (torque amplifier) truck for a cylinder wrench, which is called a meat grinder.
In the form of a drive, a drill of normal power (2 kW) is taken, drilling is organized using a mobile electricity generator. The drill should be reversible to provide reverse turns. Instead, you can take a hydraulic motor, but the first option is more economical; a motor-drill, if any, is also useful.
The reducer increases the turning moment at the head of the rod and decreases the number of revolutions. The regulator must maintain a torque of at least 4500 Nm, with a gear ratio of 1:60. The torsion amplifier is preferred on bearings, and the lubricant is changed after a batch of two dozen screw posts has been tightened. Purchase 1 more pile for trial screwing.
Manual screwing of screw piles
To make a manual svaykrut you will need a metal sheet in the form of a plate, steel reinforcement, 2 pipe sections, a grinder and welding. The strip is cut into 4 parts and welded like a glass. On opposite sides, reinforcement loops are welded, into which pipe sections are placed 2 meters long. The increased length makes screwing easier as the pieces act as levers. It takes several people to work.
Process features:
- it takes about half an hour for one pile, so a set of piles for a small building can be screwed in a day;
- screw supports are placed not only on a level platform, but also on slopes;
- piles can be loaded immediately after all foundation elements have been installed.
The scrap is inserted into the technological lugs on the tip of the pile. From both ends, pipe sections of a larger section are put on it. A magnetic level is attached to the barrel of the element to coordinate the vertical, while the slope should not be more than 1.5 °. An increase in the angle will lead to deformation of the pile, which will not appear immediately, but during the operation of the house.
