RU2334049C1 - Method of combined in situ pile manufacturing - Google Patents

Abstract

FIELD: building.

SUBSTANCE: invention refers to building, in particular to ways of erection of the bearing stilts combined on a material having rigid head embedment in a monolithic raft foundation (basement), converting building properties of poor, waterlogged, organogenic, friable and other priming coats. The method of manufacturing of the combined in situ pile includes the following technological operations: in the beginning the pilot hole is bored with a boring crown all the way down of a freezing zone, then the boring crown is replaced on fusiform roller and rolled out of driven well in an unfrozen layer of earth to design depth by ground extruding to the nearby borehole space, creating a condensed working area in the unrolled driven well, thus the diameter of the pilot hole is equal or exceeds diameter of a cylindrical part of the fusiform roller on 1-2 cm. Then the driven well is bored in an unfrozen ground to design depth and rolled out with the fusiform roller by ground extruding to the nearby borehole space, creating it the condensed working area then saturating batchwise with rubble of fraction of 20-40 mm from firm rocks: The first a driven well face, and then all unrolled driven well to straight-freezing level, thus every portion of rubble is condensed with rolling action at the full axial force transferred on the fusiform roller. Saturation with rubble is performed before arising of the conditional limiting balance between an axial force transferred on the fusiform roller and repulse of a rubble saturated ground, then the pilot hole is concreted on a layer straight-freezing level with a concrete mix of a class not lower than B 3.5 with the subsequent consolidation The consumption of rubble on saturation of a face and a lot of a trunk of the unrolled driven well is defined under formulas.

EFFECT: increase of a load-carrying capacity of poor earth foundations of the bases.

3 dwg

Description

The invention relates to the construction, in particular, to the construction of pile foundations and to technologies for increasing the bearing capacity of weak soil foundations with specific subsidence, swelling, quicksand and other properties.

A known method for the manufacture of injection piles in seasonally freezing soil (1), including the formation of a well, filling the well with cement-sand mortar to the level of freezing of the soil.

A known method of the device of stuffed piles (2), selected as a prototype, including the formation of a well without excavation and filling the well layer by layer with hardening material in the form of a rigid loose mixture with compaction of each portion.

The disadvantages of the known methods include the high complexity of the device piles in winter conditions on weak water-saturated soils with specific properties.

The objective of the invention is to increase the bearing capacity of weak soil foundations with specific subsidence, swelling, quicksand and other properties in winter conditions.

This is achieved by the fact that in the method of manufacturing a printed pile, which includes forming a well without excavating the soil, filling the well in layers with hardening material, followed by compaction of each layer, according to the invention, the leader hole is first drilled with a special drill bit for the entire thickness of the soil freezing layer. Then, a special drill bit is replaced with a spindle-shaped reamer and the well is rolled out in the unfrozen soil layer to the design depth by displacing the soil into the near-wellbore space, thereby creating a compacted zone. The diameter of the leader well is equal to or greater than the diameter of the cylindrical part of the spindle-shaped roll by 1-2 cm. Then, fractions of 20-40 mm from solid rocks are portioned with crushed stone: first, the bottom of the well, and then the whole rolled well to the level of freezing, each a portion of crushed stone is compacted by rolling with full longitudinal force transmitted to a spindle-shaped roll. Saturation with crushed stone is carried out before the onset of conditional limit equilibrium arising between the longitudinal force transmitted to the spindle-shaped pickup and the resistance of the soil saturated with crushed stone. After that, the leader well is concreted in the area of the soil freezing layer with a concrete mixture of a class of at least B 3.5 to the planning mark of the bottom of the pit, followed by compaction using the bayonet or vibration method. At the same time, the consumption of crushed stone for saturation of the face and the section of the well shaft of the rolled well located in the melt soil zone is determined by the formula

Where

- условный геометрический объем раскатанной скважины, м³;

- conditional geometric volume of the rolled well, m ³ ;

d is the diameter of the spindle-shaped reamer wells in the cylindrical part, m;

l _c - the length of the section of the cylindrical part of the rolled well, which is located in a layer of unfrozen soil, m;

l _to - the length of the conical part of the spindle-shaped reamer wells, m;

l _m = 3d is the length of the bottom saturated with crushed stone below the tip of the rolled wells, m;

k = e ₀ / e _s - coefficient taking into account the ability of the structure of the unfrozen soil layer of the near-borehole space to absorb crushed stone;

e ₀ is the porosity coefficient of the unfrozen soil layer before rolling the wells;

e _s is the coefficient of porosity of the soil in the compacted zone of the near-pile space, corresponding to its density in the dry state (ρ _ds , t / m ³ ), the value of which is determined at a distance of r _s 1.7, d m according to the schedule (figure 3), constructed according to the formula

where r is the radius of the cylindrical part of the spindle-shaped reamer wells, m;

ρ _d - the density of soft soil in the dry state to the device wells, t / m ³ ;

ρ _s is the density of soil particles, t / m ³ .

The diameter (D) of the gravel area is determined by the formula

Concrete consumption for filling the leader wellbore in the area of the soil freezing layer is determined by the formula

where d ₁ is the actual diameter of the well in the area of the soil freezing layer, m;

l is the length of the well in the area of the soil freezing layer, m;

l _u - the length of the gravel area, m

Piles made by the proposed method have the following advantages:

- have less labor, energy and materials per unit of bearing capacity;

- increase the bearing capacity of soil bases in 2.5-4 times;

- do not create vibrational effects on closely located buildings, structures and communications;

- enable their use on complex soils with specific subsidence, swelling, quicksand and other properties.

The proposed technical solution is illustrated by drawings, in which Fig. 1 shows a structural diagram of a combined stuffed pile, Fig. 2 shows the technological sequence of manufacturing a combined stuffed pile, and Fig. 3 shows a general view of the change in the density of the soil in the dry state (ρ _ds ) in the near-pile space. depending on the initial (before rolling the well) density of the soil in the dry state (ρ _d ) and the diameter of the roll d = 2r.

A method of manufacturing a combined printed piles is as follows.

First, the leader hole (1) is drilled with a special drill bit (2) over the entire thickness of the soil freezing layer without excavation, actually loosening the soil. Then, a special drill bit (2) is replaced with a spindle-shaped reamer (3) and the well (4) is rolled out in an unfrozen soil layer to the required (design) depth. The diameter (d ₁ ) of the leader well (1) is equal to or greater than the diameter (d) of the cylindrical part of the spindle-shaped reamer (3). In the rolled well (4), by displacing the soil into the near-borehole space, a compacted zone (5) is formed. And then fractions of 20-40 mm from solid rocks are portionedly saturated with crushed stone: first, the bottom hole of the well, and then the entire rolled well (4) to the level of freezing of the soil, while each portion of crushed stone is compacted by rolling with full longitudinal force transmitted to the spindle-shaped rolling machine ( 3). Saturation with crushed stone is carried out before the onset of conditional limit equilibrium arising between the longitudinal force transmitted to the spindle-shaped pickup and the resistance of the soil saturated with crushed stone. After that, the leader well (1) is concreted in the area of the soil freezing layer with a concrete mixture of a class not lower than B 3.5, followed by compaction using the bayonet method or vibration. Concreting is carried out to the planning mark of the bottom of the pit. Section (6) from the planning mark to the mouth of the leader well (1) is filled with medium-sized sand to exclude hard contact of the concrete part of the pile with the foundation being built in the future. In this case, the consumption of crushed stone (V) for saturation of the face and the borehole section of the rolled well (4) located in the unfrozen soil zone, the diameter (D) of the crushed stone section and concrete consumption (V) for filling the leader borehole (1) are determined by the formulas (a ) - (g).

The volume of a portion of crushed stone depends on the diameter (d) of the reamer, the condition of the soil being rolled out, and the technological parameters of rolling: rotation speed and longitudinal force. When performing work in winter conditions, anti-frost additives or electric heating are used to harden the concrete mixture.

Information sources

1. Patent of Russia No. 2150550, Cl. E02D 5/46, 2000.06.10.

2. Patent of Russia No. 2086733, Cl. E02D 5/34, 1997.08.10.

Claims (1)

A method of manufacturing a combined printed pile, including forming a well without excavating the soil, filling the well in layers with material, followed by compaction of each layer, characterized in that the leader is first drilled with a drill bit for the entire thickness of the soil freezing layer, then the drill bit is replaced with a spindle-shaped roll and rolled a well in an unfrozen layer of soil to the design depth by displacing the soil into the near borehole space, thereby creating a compacted zone in the rolled out well, the diameter of the leader well is equal to or greater than the diameter of the cylindrical part of the spindle-shaped raiser by 1-2 cm, after which it is portioned with crushed stone: first, the bottom of the well, and then the whole rolled well to the level of soil freezing, each portion of crushed stone is compacted by rolling full longitudinal force transmitted to the spindle-shaped roll, in addition, saturation with crushed stone is carried out before the occurrence of the conditional ultimate equilibrium arising between the transmitted to the spindle-shaped roll With the help of force and repulse of the soil saturated with crushed stone, then the leader well is concreted in the section of the soil freezing layer to the planning mark of the bottom of the pit with a concrete mixture of a class not lower than B 3.5 with subsequent compaction, while the crushed stone consumption for saturation of the face and the section of the well rolled out is determined by the formula :

Where

- conditional geometric volume of the rolled well, m ³ ; d is the diameter of the spindle-shaped reamer wells in the cylindrical part, m; l _c - the length of the section of the cylindrical part of the rolled well, which is located in unfrozen soil, m; l _to - the length of the conical part of the spindle-shaped reamer wells, m; l _m = 3 _d is the length of the bottom saturated with crushed stone below the tip of the rolled wells, m; k = e ₀ / e _s - coefficient taking into account the ability of the structure of the unfrozen soil layer near the borehole space to absorb crushed stone; e ₀ - porosity coefficient of unfrozen pounds before rolling wells; e _s is the coefficient of porosity of the soil in the compacted zone near the pile space, corresponding to its density in the dry state (ρ _ds , t / m ³ ); the diameter of the crushed stone section is determined by the formula

and the flow rate of the concrete mixture to fill the leader wellbore in the area of the soil freezing layer is determined by the formula

where d ₁ is the actual diameter of the leader well in the area of the soil freezing layer, m; l is the length of the well in the area of the soil freezing layer, m; l _u - the length of the gravel area, m

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