RU2576417C2 - Method of sinking of pile with increased bearing ability - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method of sinking of the pile includes driving of the pile into soil to a required depth by a gravitational hammer through a guiding conductor with subsequent fixing by embedment in a grillage. The pile is a metal pipe of a large diameter from 1000 to 2000 mm with a cone-shaped pointed closed end fitted with a rock cutting tip, and an anvil, and the anvil is designed in the form of a ferroconcrete cone-shaped closed end of the pile and its lower part with the ratio of the height of the filled lower part of the pile shaft to the height of the closed end cone of 0.5-1.0, reinforcing of the tip is performed in the form of curved reinforcing rods, and from above of the ferroconcrete anvil a metal circular board is installed. The pile shaft of a large diameter from 1000 to 2000 mm in the lower part is fitted with blades which are evenly placed along the diameter. The blades are rigidly fixed on the pile shaft and are made inclined at the angle of 5-30° to the pile axis, the ratio of the length of each blade to the length of the diameter of the shaft pile is selected within 0.5…1.0, the ratio of the width of each blade to the length of the diameter of the pile shaft is selected within 0.15…0.30. Bottom edges of the blades are installed at a distance from the cone of the closed end, equal to 0.5-1.0 diameters of the pile shaft, and the number n of blades placed along the diameter of the pile shaft depending on the diameter is determined from the given ratio.

EFFECT: increase of the bearing ability of the pile, decrease of material consumption and labour input.

3 cl, 4 dwg

Description

The technical solution relates to methods for immersing driven piles into the ground, mainly from metal pipes of large diameter from 1000 to 2000 mm.

In the practice of construction of pile foundations [7] they use well-proven large diameter piles with a closed end according to patent RU 17783 U1, 04/27/2001, which have a number of advantages compared to other known devices (increase in the impact energy of pile driving with a maximum efficiency with the exception deformation, swaying and tilting of the pile due to the rational construction of the anvil).

In most known methods of pile immersion (see, for example, [2-4], etc.), piles are used that represent the structure regardless of the size of the pile and the length of its diameter (see also SU 1229258 A, SU 1305249 A, SU 1337477 A, SU 1441024 A, SU 1477845 A, RU 29536U1, RU 87717U1, etc.). The patent RU 29536 U1 raises the question of the form of execution and the geometric aspect ratios of the elements, however, the patent relates to piles of small diameter (300-400 mm).

However, the diameter of the pile is an important characteristic of the pile and determines the specifics of the method of immersion in the ground, especially when constructing pile, including inclined, bridge bases in water areas, when large-diameter pipes of 1000–2000 mm are used as piles [5–7].

The prototype adopted the method [1] of piling according to patent RU 2447226 C2, 04/10/2012 for the construction of pile bridge foundations in the water area, proposed by the design and construction company Spetsfundamentstroy (SPS), which, taking into account the design of the piles developed by the company SPS "and previously protected by patent RU 17783 U1, is as follows.

A known method of immersing piles [1] involves driving a pile into the soil to the required depth with a gravity hammer through a guide conductor and then securing it by monoling in a grill, moreover, a large metal pipe from 1000 to 2000 mm with a tapered, pointed, closed end provided with a rock cutting dam is used as a pile tip, and anvil. In this case, the anvil is made in the form of a reinforced concrete cone-shaped closed end of the pile and its lower part when the ratio of the height of the filled lower part of the pile shaft to the height of the cone of the closed end is 0.5-1.0, the reinforcement of the tip is made in the form of curved reinforcing bars, and installed on top of the reinforced concrete anvil metal circular shield.

However, when the pile is immersed by the method [1], as well as by known methods [2-6], it is possible to pull out the pile under significant horizontal and vertical alternating loads, especially in difficult pound conditions.

As shown by the practice of hydraulic engineering [7], the bearing capacity of piles with the known method [1] of immersion can be increased by placing the blades on the lower part of the pile shaft. In this case, the ratios of the geometric dimensions of the elements of the immersed pile depending on its diameter play a significant role, and values close to the optimal values of these ratios can be obtained empirically.

The essence of the proposed technical solution is to create a method of immersion piles of large diameter (1000-2000 mm) of increased bearing capacity.

The main technical result is an increase in the load-bearing capacity of the pile due to the synergy of direct driving immersion with additional rotation of the pile, which is carried out when interacting with the soil of inclined blades located on the lower part of the pile shaft. The bearing capacity of large-diameter piles of 1000-2000 mm and the reliability of its immersion are increased by eliminating skew, deformation and the possibility of self-pulling piles at significant horizontal and vertical loads, which is necessary both with vertical and, to a greater extent, with inclined pile immersion. The method implements close to the optimal criterion "complexity - cost - efficiency (technical result)", i.e. achieving the highest possible technical efficiency (as well as increasing productivity) with minimal complexity and cost.

The technical result is achieved as follows.

The method of pile immersion involves driving the pile into the soil to the required depth with a gravity hammer through a guide conductor and then securing it by monoling in the grill, using a metal pipe of large diameter from 1000 to 2000 mm with a conical pointed closed end provided with a rock cutting tip and an anvil , while the anvil is made in the form of a reinforced concrete cone-shaped closed end of the pile and its lower part when the height ratio of the filled lower part with the pile to the height of the cone of the closed end 0.5-1.0, the reinforcement of the tip is performed in the form of curved reinforcing bars, and a metal circular shield is installed on top of the reinforced concrete anvil.

A distinctive feature of the method lies in the fact that the trunk of a large diameter pile from 1000 to 2000 mm in the lower part is provided with blades evenly spaced along the diameter, while the blades are rigidly fixed on the pile shaft and are inclined at an angle of 5-30 ° to the axis of the pile, the length ratio each blade to the length of the diameter of the shaft of the pile is set from 0.5 to 1.0, the ratio of the width of each blade to the length of the diameter of the shaft of the pile is selected from 0.15 to 0.30, the lower edges of the blades are set at a distance from the cone of the closed end equal to 0, 5-1.0 diameter of the pile shaft, and chi the layer η of blades placed along the diameter of the pile shaft, depending on the diameter, is determined from the ratio

n = [0.5πKcosecα],

where K = D / L is the ratio of the length of the diameter D of the pile shaft to the length L of the blade;

α is the angle of inclination of the blade to the axis of the pile;

[] is the sign of the integer part of the number.

The difference of the method is also that for the immersion of the piles use a gravity hammer with an impact mass of 10 to 20 tons.

In this case, when immersed in soil, the pile is vertical or inclined at a given angle of up to 30 ° to the vertical.

In FIG. 1 shows the design of piles of increased bearing capacity; FIG. 2 shows a diagram of the process of immersion piles, where the following notation:

1 - pile shaft (metal pipe);

2 - closed conical end of the pile;

3 - rock cutting tip;

4 - reinforced concrete anvil;

5 - curved reinforcing rods anvil;

6 - circular metal shield of the anvil;

7 - blades;

8 - shock mass of the gravitational hammer;

9 - guide conductor;

10 - grillage.

The examples in FIG. 3 illustrate the optimal placement of the blades on the lower part of the pile shaft for various values of D, L, α (diameter sweep):

a) D = 1 m, L = 0.75 m, α = 30 °, n = 4;

b) D = 2 m, L = 1.0 m, α = 30 °, n = 6;

c) D = 1 m, L = 1.0 m, α = 14.5 °, n = 6;

d) D = 1 m, L = 0.75 m, α = 14.5 °, n = 8.

In FIG. 4 shows possible options for the implementation of the blades in the form of a trapezoid, rectangle, triangle.

Piling 1 is carried out in three stages (Fig. 2):

- 1st stage: installation and direction (orientation) of the pile 1 by means of a conductor 9 (for example, using technology [1]), placement of the impact mass 8 of the gravitational hammer in the pile shaft (Fig. 2.1);

- 2nd stage: immersion of the pile 1 by driving the impact mass 8 of the gravitational hammer with rotation due to the interaction of the inclined blades 7 of the pile 1 with the ground (Fig. 2.2);

- 3rd stage: the exclusion of pulling the piles 1 by monolithic the head of the pile in the grillage 10 (Fig. 2.3.).

To immerse piles 1, piling equipment and conductors described in [1], as well as a gravity hammer (not shown) of the SPS brand according to patent RU35539U1, 20.01.2004 can be used.

An impact mass of 8 from 10 to 20 tons, made in the form of a monolithic load suspended on a cable, freely falls inside the trunk of a large pile pile 1 from 1000 to 2000 mm and interacts with a reinforced concrete anvil 4 through impact. Under the influence of these impacts and the axial load of the pile 1, the closed conical end 2 of the pile 1 with the rock cutting tip 3 is driven into the soil by crushing, crushing and moving the rock. Reinforcing rods 5 of reinforced concrete anvil 4 serve to strengthen (increase the strength) of anvil 4 when interacting with impact mass 8. A circular metal shield 6 mounted on top of anvil 4 also performs reinforcing functions and prevents the destruction of anvil 4 from impacts of mass 8. Anvil 4 represents filled reinforced concrete, the conical closed end 2 of the pile 1 and its lower part, and the greatest impact efficiency of mass 8 (maximum impact efficiency) is achieved with anvil mass of 4, which is determined (RU 17783 U1) with a ratio of the height of the filled lower part of the pile shaft 1 to the height of the cone of the closed end 2 from 0.5 to 1.0.

An essential feature of the technical solution that determines the technical result is the installation on the lower part of the trunk of a pile 1 of large diameter from 1000 to 2000 mm blades 7, which are uniformly placed in diameter at equal angular distances (Fig. 3). In this case, the blades 7 are rigidly fixed to the pile shaft and are inclined at an angle of 5-30 ° to the axis of the pile, the ratio of the length of each blade to the length of the diameter of the pile shaft is set from 0.5 to 1.0, the ratio of the width of each blade to the length of the diameter of the pile shaft choose from 0.15 to 0.30, the lower edges of the blades are set at a distance from the cone of the closed end equal to 0.5-1.0 of the diameter of the pile shaft, and the number η of blades placed along the diameter of the pile shaft, depending on the diameter, is determined from relations (1).

The given numerical ratios are obtained as a result of production tests in the practice of construction of pile foundations and are optimal for large diameter metal pipes from 1000 to 2000 mm.

Thus, the pulling forces during the immersion of the pile are perceived and compensated by the lateral surfaces of the pile 1 and the inclined blades 7. The final installation of the pile is completed by monoling the body of the pile 1 in the grill 10 (Fig. 2.3).

The blades 7 in specific cases can be made in the form of a trapezoid, rectangle, triangle (Fig. 4). Depending on the requirements and installation conditions, the pile is vertical or inclined at a given angle of up to 30 ° to the vertical.

An increase in the bearing capacity of the pile is ensured by a synergy of essential features: the combination of the use of an anvil in the closed conical lower end of the pile, the blade bottom of the pile and the optimal geometric ratios of the pile elements (diameter and blades) obtained empirically for large piles from 1000 to 2000 mm.

Tests carried out at the SFS company confirmed the achievement of increased bearing capacity of piles with the above-described placement and size of inclined blades. At the same time, the proposed pile with increased bearing capacity is adequate for a screw pile (axial displacement in combination with rotation) with the exception of the use of rotation drives and their control devices, which simplifies the process of pile immersion while increasing its efficiency and productivity.

BACKGROUND OF THE INVENTION

I. Prototype and analogue:

1. RU 2447226 C2, 04/10/2012 (prototype).

2. RU 2052018 C1, 01/10/1996 (analogue).

II. Additional sources of prior art:

3. RU 21166024 C2, 04/27/2001.

4. RU 2230170 C2, 06/10/2004.

5. RU 2483153 C2, 05.27.2013.

6.JP 4574273 B2, 11/04/2010.

7.http: //www.specfandament.ru.

Claims (3)

1. A method of immersing piles, including driving a pile into the soil to the required depth with a gravity hammer through a guiding conductor, followed by fixing by grouting in a grill, and using a large diameter metal pipe from 1000 to 2000 mm with a conical pointed closed end provided with a rock cutting tip and anvil, while the anvil is made in the form of a reinforced concrete cone-shaped closed end of the pile and its lower part with a height ratio of the filled lower part the pile shaft to the height of the cone of the closed end 0.5-1.0, the reinforcement of the tip is made in the form of curved reinforcing bars, and a metal circular shield is installed on top of the reinforced concrete anvil, characterized in that the trunk of the pile is large in diameter from 1000 to 2000 mm in the lower part the blades are uniformly spaced along the diameter, while the blades are rigidly fixed to the pile shaft and are inclined at an angle of 5-30 ° to the axis of the pile, the ratio of the length of each blade to the length of the diameter of the pile shaft is set from 0.5 to 1.0, the ratio of the width of each lo Depending on the length of the pile shaft diameter, choose from 0.15 to 0.30, the lower edges of the blades are set at a distance from the closed end cone equal to 0.5-1.0 of the diameter of the pile shaft, and the number n of blades placed along the diameter of the pile shaft, depending on the diameter is determined from the ratio
n = [0.5πKcosecα],
where K = D / L is the ratio of the length of the diameter D of the pile shaft to the length L of the blade;
α is the angle of inclination of the blade to the axis of the pile;
[] is the sign of the integer part of the number. 2. The method according to p. 1, characterized in that for the immersion of the piles use a gravity hammer with an impact mass of from 10 to 20 tons. 3. The method according to p. 1, characterized in that when immersed in soil, the pile is vertical or inclined at a given angle of up to 30 ° to the vertical.

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