RU-2861522-C1 - METHOD FOR CONSTRUCTING BORED-INJECTION PILE IN PERMAFROST SOILS

Abstract

FIELD: construction. SUBSTANCE: invention can be used in the construction of pile foundations for new buildings, in reinforcing foundations of existing buildings and structures, and also as anchor fastenings for excavations in areas of permafrost distribution while preserving the foundation soils in a frozen state during construction and throughout the entire period of operation of the building or structure. A method for constructing a bored-injection pile in permafrost soils includes drilling a well in a soil foundation using a tubular anchor rod with its sectional extension along the length by means of threaded coupling sleeves, where the first rod section is equipped with a drill bit having nozzles for supplying a solution. While drilling the well, a washing solution is simultaneously supplied into the anchor rod, ensuring its exit from the nozzles of the drill bit, followed by injecting a hardening working solution through the anchor rod into the well with displacement of drill cuttings from the well to ensure the load-bearing capacity of the bored-injection pile along the shaft and the ground. Washing the anchor rod with water and subsequently filling it with a liquid refrigerant, where a liquid suspension consisting of cement and water, prepared in a water:cement ratio of 0.9-1.0, is used as the washing solution, and a thick suspension consisting of sand-cement and water, prepared in a water:cement ratio of 0.20-0.25, is used as the hardening working solution. EFFECT: reduction of the thawing zone of the permafrost soil foundation along the shaft of the bored-injection pile, shortening the freezing time of the pile with the permafrost foundation soil, and ensuring the required load-bearing capacity with respect to the ground and the material at early stages after the pile installation. 1 cl, 1 dwg

Inventors

• Salnyi Ivan Sergeevich
• Pronozin Iakov Aleksandrovich
• Naumkina Iuliia Vladimirovna
• EPIFANTSEVA LARISA RAFAILOVNA
• Muslova Daria Dmitrievna

Dates

Publication Date

20260505

Application Date

20250811

Claims (1)

1. A method for installing a bored-injection pile in permafrost soils, which includes drilling a borehole in the soil base using a tubular anchor rod with its sectional extension along the length by means of threaded connecting couplings, where the first section of the rod is equipped with a drill bit having nozzles for feeding a solution, while during the drilling of the borehole, a flushing solution is simultaneously fed into the anchor rod, ensuring its exit from the nozzles of the drill bit; subsequent injection of a hardening working solution through the anchor rod into the borehole with displacement of drill cuttings from the borehole to ensure the bearing capacity of the bored pile along the shaft and the soil, flushing the anchor rod with water and subsequently filling it with a liquid coolant, wherein a liquid suspension consisting of cement and water, prepared in a ratio of W:C = 0.9-1.0, is used as the flushing solution, and a thick suspension consisting of sand-cement and water, prepared in a ratio of W:C = 0.20-0.25, is used as the hardening working solution.

Description

The invention relates to construction and can be used in the construction of pile foundations for new buildings, in strengthening the foundations of existing buildings and structures, and also as anchor fastenings for excavations in areas where permafrost soils are widespread, while maintaining the foundation soils in a frozen state during the construction process and throughout the entire period of operation of the building or structure. The most common method for constructing pile foundations in permafrost areas is the bored-and-drop method (see Recommendations for the Construction of Pile Foundations in Permafrost Soils. Moscow: N.M. Gersevanov Research Institute of Instrument Engineering, 1985). This method involves driving the pile into a pre-drilled borehole, the diameter of which exceeds the largest cross-sectional dimension of the pile by 5 cm or more, and filling the borehole with a soil solution. The load-bearing capacity of such piles is ensured by freezing the permafrost soil along its lateral surface and by the resistance of the permafrost soil beneath the pile's lower end. The disadvantages of the bored-and-run method are: the need for large-sized equipment for installing piles, the length limitation due to the standard sizes of piles, the difficulty of using it when strengthening existing structures, the large volume of drilling work, the possibility of lifting piles in heaving soils, prolonged freezing of the pile with the surrounding soil, and an increase in construction time due to the introduction of a large amount of heat when filling the borehole with mortar. A bored-and-drop steel tubular thermal pile with a support-anchor extension is known (Patent for Utility Model of the Russian Federation No. 145989, IPC E02D 5/22, published on September 27, 2014, Bulletin No. 27), consisting of a tubular shaft with a support plate welded to the upper end of the shaft, characterized in that a round flat steel support disk and several steel vertical stiffeners connecting the disk to the pile shaft are welded to the lower end of the pile shaft, wherein the diameter of the disk is greater than the diameter of the pile shaft, and the disk together with the stiffeners is completely located in the thickness of permafrost soil. A finished pile without a refrigerant is installed in a pre-drilled hole in the thickness of permafrost soil to the design mark on a crushed stone cushion. The gap between the pile and the borehole is filled with non-heaving soil. Coolant (kerosene) is then added to the pile, and the foundation block is placed on the supporting sheet. This increases the pile's bearing capacity relative to a non-heavy pile due to the increased bearing area and the increased surface area between the pile and the surrounding frozen soil. At the same time, the pile's resistance to the tangential frost heaving forces that occur when the active soil freezes is increased. The disadvantages of this technical solution include the need for large-scale equipment for installing piles, the possible collapse of thawed soft soils in the upper part of the foundation, the length limitation of the pile standard sizes, the difficulty of using it to strengthen existing structures, the large volume of drilling work, and the low bearing capacity of the pile on the lateral surface. Another common method of constructing pile foundations in permafrost soil areas is the driven pile method (see Recommendations for the Construction of Pile Foundations in Permafrost Soils. Moscow: N.M. Gersevanov Research Institute of Instrument Engineering, 1985), in which piles are driven into pre-drilled leader holes 1-2 cm smaller in diameter than the pile diameter. The advantages of the driven pile method include insignificant heating of the permafrost foundation soils and rapid freezing of the piles with the surrounding soil, a 2-2.5-fold reduction in the amount of drilling work compared to the driven pile method, no need to use soil solutions to fill the holes, i.e. there are no wet processes, and an increase in the bearing capacity of the piles when filling the sinuses with clay mortar compared to driven piles. The disadvantages of this method include: the need for large-scale equipment for installing piles, applicability only in plastically frozen soils, difficulty in driving piles to the design depths, frequent breakage of piles when attempting to drive them to design marks, increased requirements for dimensional accuracy and the quality of borehole preparation, limited conditions of application, and complication of work. A tubular steel rotary thermal pile is known (Patent for Utility Model of the Russian Federation No. 141226, IPC E02D 27/35, published on May 27, 2014, Bulletin No. 15), consisting of a shaft with a sealed cavity filled with a liquid coolant, containing in the lower part of the shaft, above the pile tip, at least 3 wedge-shaped steel ribs, 2 or more times the shaft diameter in height and 10-12 mm thick, welded to th