RU2707228C1 - Method to immerse piles in seasonal-frozen ground - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the field of construction, in particular, to the pile foundations from prefabricated driving piles, submersed at negative temperatures in seasonal-frozen ground. Method of piles immersion into seasonal-frozen ground includes preliminary drilling of wells with thermovibroleader in places of piles immersion, made in the form of cylindrical hollow bar with tip on one side and rigidly connected flange with opposite, on which vibration submersible is installed, with subsequent final driving of piles into obtained wells. Thermovibroleader is installed on mast of copra, which implements piling, on adjacent edge of pile hammer, between tip and rod there is adapter, which is rigidly fixed to rod, and connection with tip is detachable. Tip of the thermovibroleader has a cone-shaped shape, in the central cavity of which there is a heat-resistant insulator with a screw slot on the outer surface, containing a heating spiral with high specific resistance, a heat-resistant elastic gasket is installed between the insulator and the adapter to exclude axial movements of the insulator. On external surface of tip radially directed ribs with internal longitudinal channels are rigidly fixed, and in walls of tip there are transverse radially arranged holes. Before immersion of thermovibroleader the tip is heated and then submerged into seasonal-frozen soil with included spiral, and after soil development thermovibroleader is removed.

EFFECT: technical result consists in improvement of efficiency of device pile foundations of buildings of prefabricated piles, submersed at negative temperatures in seasonal-frozen soil by reducing costs when installing foundations by preventing destruction of piles during their immersion through a frozen layer, as well as reducing values of deviations of piles in planned position, allowing to increase the speed of wells in frozen soils.

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Description

The invention relates to the field of construction, in particular to the device of pile foundations from driven factory-made piles, submerged at low temperatures in seasonally frozen soil.

Frozen soil due to freezing of free fluid in it is characterized by the properties of increased resistance when immersing pile elements. It is known that the “instantaneous” strength of such soil when driving piles is tens or even hundreds of times higher than for soil in a thawed state. In clay soils, this condition begins at a temperature of -0.5 to -5.0 degrees Celsius. Under such conditions and the thickness of the frozen layer up to 2-3 m when driving piles under traditional conditions, their trunks are destroyed due to an increase in the number of hammer blows. This problem is partially solved by increasing the strength characteristics of the pile material by increasing the class of concrete to B30-B35 or by increasing the transverse reinforcement of piles. However, this increases the cost of manufacturing piles by 30%. Even if it is possible to immerse the pile, punching the indicated thickness of the soil, then, as experience shows, when diving, the processes of displacement of the pile in a planned position and its lateral sliding along the frozen crust of the soil having the greatest strength characteristics occur. This leads to displacements of the piles in the planned position up to 20-30 cm. Thus, the geometric centers of the piles do not coincide with the axes of the supporting structures of walls or columns, which requires either immersion of duplicate elements or an increase in reinforcement of grillages for the perception of super-design bending moments.

A known method of immersion of a pile is bored, in which it is immersed in pre-drilled leader wells, the diameter of which is 1-2 cm less than the smallest cross-sectional area of the pile. For drilling, mainly self-propelled drilling rigs equipped with screws are used (SP 45.13330.2017 Earthworks, foundations and foundations, clause 12.6; SNiP 3.02.01-87 Earthworks, foundations and foundations, clause 11.44).

The disadvantage of this method is the additional cost of using drilling machines and soil disposal, which also leads to increased labor costs and reduced productivity. In addition, if there are cramped conditions at the construction site, it is not always possible to place an additional set of drilling equipment, an excavator and vehicles for removing soil.

The closest analogue to the claimed invention is a method of immersing piles in wells arranged in a combined way by a steam thermal vibro-leader, The drilling rig consists of a pipe-laying unit TO-15-30, a vibro-loader VPP-2A or B-401, a thermal vibration guide and a guide. In addition, a steam generator and a power plant are introduced, which are moved by means of a tractor. The steam thermal vibro-leader thaws frozen soil to the required depth with economical steam consumption and fast freezing of piles. For this method, a maximum penetration rate of 8-40 m / h was noted (see Badin G.M. Mechanization of pile work in winter conditions. - L.: Stroyizdat. Leningra. Department, 1987, pp. 24-27, 75- 79, Fig. 22-23).

The disadvantage of this method is the need for additional space for a drilling rig and a mobile container containing a steam generator and a power plant, moved by a tractor. In addition, the use of steam generators is currently irrelevant, unproductive, such equipment is not mass-produced, which calls into question its mass use. Thus, this method is ineffective by the criterion of using modern machines and equipment for work in conditions of freezing temperatures.

The essence of the claimed invention lies in the fact that in the known method of immersing piles in seasonally frozen soil, including preliminary drilling of wells with a thermal vibro-leader in the places of immersion of piles, made in the form of a cylindrical hollow rod with a tip on one side and a rigidly connected flange with the opposite, on which is installed a vibration loader, with subsequent final driving of the piles into the obtained wells, according to the change in the thermal vibrator, is installed on the mast of the copra, immersing the piles, and its adjacent face with a pile hammer, between the tip and the rod there is an adapter that is rigidly fixed to the rod, and the connection with the tip is detachable, the tip of the thermal vibro-driver has a conical shape, in the central cavity of which there is a heat-resistant insulator with a screw groove on the outer surface that accommodates the heating a spiral with a large resistivity, a heat-resistant elastic gasket is installed between the insulator and the adapter to prevent axial movements of the insulator, on the outer surface rhnosti tip rigidly fixed radially directed ribs with internal longitudinal channels, and transverse walls of the tip are made radially arranged holes, wherein prior to immersion termovibrolidera tip is heated and then dipped in a spiral enabled, and after excavation termovibrolider recovered. Moreover, the thermovibrolider can be removed from the formed well when the spiral is on, and the cross section of the tip of the thermovibrolider can be cylindrical or multifaceted.

The technical result provided by the claimed invention is to increase the efficiency of construction of pile foundations of buildings from prefabricated driven piles, submerged at low temperatures in seasonally frozen soil by lowering the costs of building foundations by eliminating the destruction of pile trunks when they are immersed through the frozen layer, and also reduce the values of deviations of piles in the planned position, allowing you to increase the speed of the device wells in frozen soils.

The essence of the proposed method of immersion piles is illustrated by drawings, where:

- in FIG. 1 schematically shows a pile driver immersing piles with a thermal vibro-leader installed on its mast;

- in FIG. 2 schematically shows the construction of a thermovibrolider;

- in FIG. 3 schematically depicts a cross-sectional shape of the tip of a thermovibrolider.

The thermal vibro-leader is installed on the mast of the copra, immersing piles, on its adjacent face with a pile hammer (Fig. 1). The thermovibrolider is made in the form of a cylindrical hollow rod 1 with a tip 2 on one side and a rigidly connected flange 3 with the opposite one, on which a vibration loader is mounted (not shown in Fig. 2). An adapter 4 is located between the tip 2 and the rod 1, which is rigidly fixed to the rod 1, and the connection with the tip 2 is detachable, for example, threaded, and to prevent loosening of the connection, its locking is provided. The tip 2 of the thermovibrolider has a conical shape, in the central cavity of which there is a heat-resistant insulator 5 with a screw groove on the outer surface, accommodating a heating coil 6 made of wire with high resistivity. The power supply of the spiral is carried out using a cable 7, passed through the Central hole of the thermal vibroloader. Between the insulator 5 and the adapter 4, a heat-resistant elastic gasket 8 is installed to exclude axial movements of the insulator 5. On the outer surface of the tip 2, radially directed ribs 9 with internal longitudinal channels 10 are rigidly fixed. In the walls of the tip 2 there are transverse radially located holes 11. The ribs 9 serve to cutting the soil mass and violating its solidity, but also to transfer additional heat to it, which leads to the intensification of thawing processes. The channels 10 and openings 11 serve for intense heat transfer through the walls of the tip 2 and ribs 9 by reducing the volume of heated steel elements (Fig. 2). The cross section of the tip 2 of the thermovibrolider can be made cylindrical or multifaceted, for example square (Fig. 3). The cross-sectional shape of the tip 2 of the thermovibrolider is selected depending on the parameters of the immersed piles.

The method of immersion piles in seasonally frozen soil is as follows.

Previously, in the places where the piles were immersed, leader wells were arranged to the depth of the frozen ground. soil. Wells are arranged by means of a thermal vibro-leader installed on the copra mast, on its adjacent face with a pile hammer and moved along it using guides under the influence of a cable transmission.

Before the immersion of the thermovibrolider, its tip, together with the ribs, is closed with a cover of heat-insulating material, and the heating coil is included in the electrical network. The heat generated by the spiral heats the walls, ribs and tip of the tip. After reaching the required degree of heating, the cover is removed and immersion of the thermal vibro-leader is started. Diving lead with the spiral on. In this case, the heat released to it is summed up with the heat arising from the friction of the tip against the soil, and causes it to thaw in the wall zone and under the tip. The size of the thawing zone depends on the amount of heat generated by the spiral and is determined by the amount of energy consumed and the thermophysical properties of the developed soil. In order to more efficiently transfer heat from the spiral to the soil mass, and, consequently, to increase the thawing zone, the design of the thermovibrolider provides for an increase in the surface heat transfer achieved by ribs, which are used to violate the integrity and cutting of the frozen ground mass and to transfer heat to it outside tip leader. The sizes and number of ribs are set depending on the size of the tip and the piles immersed in the soil (traditionally used sizes are 300 × 300, 350 × 350 and 400 × 400 mm). After immersing the thermovibrolider to the required depth equal to the thickness of the freezing layer (up to 2-3 m), the thermovibrolider is removed, and to increase the thawing zone, extraction can be performed with the spiral turned on. Thus, in a frozen soil they form a well with a thawed zone of soil and a destroyed monolithic wall, providing a decrease in soil resistance with further immersion of the pile. After the thermovibrolider is removed, the pile is immediately driven into the formed well, ensuring that the walls of the well do not freeze and the melt soil is poured in it. Pile driving is carried out under standard conditions characteristic of immersion at positive temperatures.

In addition, with an increase in the mass of the hammer, pile driving is also possible without the use of leader wells. In this case, guiding wells are arranged by means of a thermovibrolider in the ground, which, when freezing in the ground, form a rigid conductor, which, in turn, eliminates pile displacement in the planned position, which is often observed without additional measures. This allows you to eliminate the additional costs when installing grillages in the form of its strengthening - increasing reinforcement, the device monolithic broadening, etc.

Thus, the method of immersing piles in seasonally frozen soil can improve the efficiency and reliability of the process of immersing piles in such soil by eliminating the destruction of pile trunks when they are immersed through the frozen layer, as well as reducing the values of deviations of piles in the planned position, allowing you to increase the speed of the device wells in frozen soils.

Claims (4)

1. A method of immersing piles in seasonally frozen soil, including preliminary drilling of wells with a thermal vibro-leader in the places of immersion of piles, made in the form of a cylindrical hollow rod with a tip on one side and a rigidly connected flange with the opposite one on which a vibrating loader is installed, followed by final driving of the piles in the obtained wells, characterized in that the thermal vibrator is installed on the copra mast, immersing piles, on its adjacent face with a pile hammer, between the tip and rods the adapter is located, which is rigidly fixed with the rod, and the connection with the tip is detachable, the tip of the thermovibrolider has a conical shape, in the central cavity of which there is a heat-resistant insulator with a screw groove on the outer surface, accommodating a heating coil with a high resistivity, between the insulator and the adapter heat-resistant elastic gasket to exclude axial movements of the insulator, radially directed sconces with internal longitudinal channels, and in the walls of the tip there are transverse radially located holes, and before immersion of the thermal vibro-driver, the tip is heated and then immersed with the spiral turned on, and after development of the soil, the thermal-vibro-leader is removed. 2. The method of immersing piles according to claim 1, characterized in that the thermal vibro-leader is removed from the formed well with the helix turned on. 3. The method of immersion piles according to paragraphs. 1 and 2, characterized in that the cross section of the tip of the thermovibrolider is cylindrical. 4. The method of immersion piles according to paragraphs. 1 and 2, characterized in that the cross section of the tip of the thermovibrolider is multifaceted.

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