RU2646267C1 - Precast pile with widening - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: precast pile with a broadening is intended for the construction of buildings pile foundations. Broadening of the pile is above the point. Broadening is made in the shape of a collection cone, combined with a barrel with a splined pane. Pane is freely passed through the molding damper in the pile shaft.

EFFECT: decrease in the material consumption of pile foundations and the laboriousness of their implementation.

3 cl, 4 dwg

Description

The invention relates to the field of construction, in particular to the implementation of pile foundations using driven piles.

Of the total piles used in Russia, up to 80% are driven. The achieved effect of their use will stimulate the search for new progressive solutions of piles. Considering that in the magnitude of the bearing capacity of driven piles, the friction forces on the soil along the lateral surface of the piles are on average only 20 ... 25%, the constant desire to increase their bearing capacity by means of broadening increases the cross section of the piles.

There is a known solution to a driven pile, including the tip of the trunk with widenings arranged in tiers along its height at a distance from each other, with the average projection of the widenings on the horizontal plane located above the lower broadening in the trunk section not more than 2/3 of its height exceeds not less than than 1.2 times the projection area on the horizontal plane of the lower broadening. The broadening can be performed on the lower sections of one or two side faces of the barrel, and at least two side faces of the barrel can be inclined to the transverse axis of the barrel, and the broadening is located on the inclined sides of the barrel. In addition, the broadening can be located along the height of the barrel at a distance from each other (10-60) b, where b is the overhang of the overlying broadening, while the overhang of the lower broadening does not exceed 1/2 of the trunk diameter or the width of the face on which the broadening is located. (RF patent 2023110).

An increase in the bearing capacity of piles with broadening of such a design is achieved mainly due to soil friction along the lateral surface of discretely broadened sections of the pile, which form local zones of compacted soil as they sink. The magnitude of the soil resistance forces in the area of broadening along the height of the pile is uncertain and ineffective. With a variety of physicomechanical characteristics and thickness of the cut soil, the proposed broadening does not ensure the constancy of the bearing capacity of the pile. In a pile field, its value can have a large spread, which during the operation of the building does not guarantee the uniformity of its precipitation. The formwork of such piles has a complex geometry and is not technologically advanced in mass production, while the various options for the location of the broadening along the height of the trunks exclude the possibility of their unification.

The closest known solution for driving piles broadening is a method of pile construction, including immersion of a driven pile into the soil through the concrete body of the drill pile, at a depth below the level of the drill pile at least 1 meter, while a cavity is installed in the bored pile and after the set the strength of concrete, the device is driven by a driven pile in the cavity, and the drilling and driven piles are combined with a common grillage using reinforcing outlets of piles. The space between the bored and driven piles, according to the description, is filled with fine-grained concrete. (Patent No. 2520314).

The main disadvantage of this solution is associated with the high complexity of the work on the implementation of the broadening. The combined solution of piles associated with the use of drilling (monolithic) technology and technology for driving precast piles, as well as with the need to fill gaps along their perimeter with monolithic concrete, increases the complexity, organizationally and technically complicates the construction of such piles. Dynamic effects when immersing the driven part of the pile violate the integrity of the concrete body of the drill pile, which reduces its reliability. Even with piles of the same size, the complexity of their quality control determines a large spread (up to 20-30%) of the bearing capacity, especially in unstable soils. The proposed combination of the driven part of the pile with monolithic broadening by a common monolithic grillage, performed with the help of reinforcing outlets, "condemns" the location of the broadening either at the level of only the top of the pile, which is ineffective, or at almost the full height of the combined driven part. Both solutions do not justify the excessive costs of its device. When performing piles, technological breaks are needed to increase the time of work.

The purpose of the invention is to simplify the design and technology of the device for driving piles with broadening, reducing their material consumption and the complexity of work on the device for broadening, increasing the reliability of piles and production culture, as well as expanding the scope of these piles. The goals are achieved by a combination of features, characterized in that the broadening placed on the pile shaft above its tip is made in the form of a pre-assembled cage combined with a shaft using a key insert freely passed through a forming damper insert placed in the pile shaft.

On the stem of the driven pile, mainly in the upper part, additional shaping damper inserts placed with a uniform pitch, as well as an additional clip of broadening can be installed.

The implementation of the broadening in the form of a prefabricated clip simplifies the design and all the technological processes for the broadening device, while the factory production technology of the clip provides control, quality and reliability of the product. The clip is carried out in compliance with standard technological and mounting tolerances. It can be performed both as a whole (volumetric), and as a composite of two U-shaped parts.

The dimensions of the cage and its placement on the trunk are taken based on an analysis of soil conditions, while achieving the maximum effect of increasing the bearing capacity of piles.

The combination of the cage with the pile shaft, realized with the help of a freely installed key insert made, for example, in the form of a metal plate (preferably) or in the form of a standard metal profile of the design section, simplifies the design solution and facilitates the whole complex of works on combining the broadening with the shaft. The calculation of the key insert is performed according to the known rules for calculating the keys. Corrosion protection of the insert, if necessary, is carried out in a known manner or its calculated thickness is taken into account partial corrosion.

The installation of a mold-forming damper insert in the stem of the driven pile for skipping the key insert when driving the pile reduces the impact stiffness and contact stresses in the concrete in the installation area of the key insert, which ensures the integrity of the concrete. The liner is box-shaped, for example, from hardwood. For an unobstructed establishment and installation of a key insert, the dimensions of the insert cavity are taken into account with mounting tolerances.

The installation of additional shaping damper inserts in the trunk and their placement with a uniform pitch allows, in the process of driving piles, taking into account the complexity of soil conditions, to vary the placement of the broadening clip along the height of the trunk, while ensuring the maximum effect of its use. With in-line factory production, the manufacture of trunks with a unified arrangement of liners makes it possible to unify components and the range of trunks.

Placing an additional broadening cage on the pile shaft, mainly in the upper part, makes it possible to transfer significant, for example, seismic horizontal loads to the shaft. In buildings with a cold underground, the cage can be used as a head, for example, to support beam structures of the grillage.

The invention is illustrated by the following graphic materials.

FIG. 1 is a general view of a driven pile without additional broadening.

FIG. 2 is a view according to 1-1 in FIG. one.

FIG. 3 is a general view of a driven pile with additional broadening.

FIG. 4. - section 2-2 in FIG. 13.

Size "c" in FIG. 1, 2 - the step of installation of shaping damper inserts unified along the height of the barrel. The dimension "d" in FIG. 1 ... 3 - the minimum size that determines the location of the casing broadening from the tip of the barrel, taken when deepening the barrel:

- in coarse, gravel, large and medium-sized sandy, dusty-clay soils with a fluidity index I _L ≤0.1 - not less than 0.5 m,

- to other non-rocky soils - at least 1.0 m,

- in dusty clay soils with a yield index I _L = 0.6 or more - at least 2 m.

The constructive solution of the pile with broadening of the trunk is designed for the conditions of its operation as a "hanging" pile.

The proposed pile includes a one-piece prefabricated reinforced concrete barrel 1 and a broadening sleeve 3 combined with it using a key insert 2. The dimensions of the holder are set by design requirements. To pass the insert 2 through the barrel 1, a shaping damper insert 4 is installed in its body 4. For removal from the mold and transportation of the barrel 1, for example, mounting loops or eyebolts 5 having unscrewed loops are installed in it. The broadening cage 3 is equipped with mounting loops 6. The dimensions of the cavity in the cage are taken in compliance with standard tolerances for the manufacture and installation of the barrel 1 and key insert 2 on them. On the barrel 1, additional damper inserts 4 and an additional broadening cage 3 can be installed with a unified pitch.

Immersion of the driven pile shown in FIG. 1 is performed as follows.

After the preparatory work is completed, the piling axes are marked and fixed in accordance with the design. Along the marked axes, a broadening sleeve 3 is installed in the design position on a leveled base with a copra. Its verticality and mounting stability are provided in a known manner, for example, using a mounting jig or temporary struts. In the cavity of the stably secured holder 3 freely lead and lower the barrel 1, while its design position is provided by the holder. Before raising the barrel 1 to the pile driver, the lower mounting loop or eye-bolt loop 5 is cut or unscrewed, respectively. After removing the conductor or temporary struts from the cage 3, the barrel 1 is driven down to a depth of 5 ... 10 cm above the design location on the top barrel of the broadening cage 3, then the driving is stopped and the key insert 2 is freely passed through the forming damper insert 4 in the barrel 1. If necessary, in the mounting clearances of the insert 4, the insert 2 is interlinked within the limits that ensure the reference planes of the insert 2 and the broadening support 3 are aligned. After a visual check of the correct installation of the keyed insert 2, heave further pile driving until it reaches a control failure. The first 1 ... 1.5 m driving is carried out in a gentle mode. The stability and integrity of the barrel 1 in the process of driving is provided by its strength and rigidity. If necessary, according to the results of driving perform control static tests.

The proposed solution for the device for broadening driven piles is applicable to the well-known standard precast reinforced concrete piles, performed without prestressed reinforcement. The design of the clip has a factory quality guarantee. The technology for installing it on the barrel is as simple as possible and provides the possibility of visual control.

The constructive solution of the proposed driven pile and the achieved technical and economic result ensure its high competitiveness, while the broadening device in the form of a separate prefabricated element does not violate the traditional manufacturing technology and equipment of standard solid piles adopted, for example, according to the series 1.011.1-10 of the Construction Catalog RF

The use of piles of the proposed design limits or eliminates the use of expensive composite piles of equivalent bearing capacity.

When driving piles with broadening near emergency buildings, in cramped conditions of dense urban and industrial development, as well as in the immediate vicinity of existing foundations, well-known gentle methods of driving piles can be used, for example, the indentation method or the use of leader drilling while driving, reducing dynamic effects (vibrations) ) on the surrounding buildings.

Compared with solutions of pile foundations using typical solid and composite driven piles, the material consumption of the proposed piles, with their equal bearing capacity and deformability, is 2 or more times less, which ensures the economic feasibility of their widespread use. The absence of "wet" processes with the device of the broadening of piles, made in the form of a prefabricated structure, increases the reliability of pile foundations and the culture of work.

Claims (3)

1. A driven pile with a broadening placed on the trunk above its tip, characterized in that the broadening is made in the form of a collar combined with a shaft using a key insert freely passed through a forming damper insert placed in the pile trunk. 2. A driven pile according to claim 1, characterized in that additional shaping damper inserts are placed in the pile shaft, placed with a uniform pitch. 3. A driven pile according to claim 1, characterized in that an additional clip of broadening is installed on the trunk, mainly in its upper part.

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