RU2602524C1 - Method for making a combined built-in-place pile - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction, in particular, to methods for installation of material-combined piles with rigid attachment of the cap in foundation. Method for making a carrier material-combined built-in-place pile comprises formation of a well by soil excavation or without soil excavation. When by-layer filling the well with rigid loose mixture with further compaction of each layer, the volume of crushed stone portions is being calculated by the formula: V_{crushed stone} = (from 0.5 to 1.5)·V_die·k, where V_{crushed stone} - volume of a crushed stone portion; V_die - volume of a cylindrical-conical die; k - coefficient of seal of crushed stone, crushed stone is being compacted by immersion of a rotating cylindrical-conical die with axial force, selected from a calculation

where F_axial - axial force, H; R_specific - specific resistivity of the immersion of a cone in the range from 1 to 4 Mpa; d_die - diameter of a cylindrical section of the die, m. Crushed stone is being saturated to the final grade. Then, upper section of the well is being reinforced concreted to form the pile head.

EFFECT: technical result is stabilizing properties of soil bases.

1 cl, 1 dwg

Description

The invention relates to the construction, in particular, to methods of erecting piles combined according to the material, having a rigid incorporation of the tip into the foundation and increasing the bearing capacity of soft soils.

A known method for the manufacture of injection piles in seasonally frozen ground (Patent for the invention of the Russian Federation No. 2150550), including the formation of a well, filling the well with cement-sand mortar to the level of freezing of the soil.

The disadvantage of this method is significantly lower bearing capacity of drilling piles compared to bored.

There is a method of manufacturing a carrier of a stuffed pile combined by material, selected as a prototype (Patent for the invention of the Russian Federation No. 2334048). The method consists in the formation of a well without excavation, layer-by-layer filling of the well with rubble, followed by compaction of each layer. Compaction is performed with full longitudinal force on the breech. Crushed stone is saturated until equilibrium arises between the axial force on the pick-up bar and the resistance of the soil saturated with crushed stone.

The disadvantage of this method is the uncertainty of the relationship between the diameter of the roll and the longitudinal force on it. With a small longitudinal force, compaction of crushed stone may be insufficient to transfer axial loads from the building to the ground, which will lead to excessive subsidence of the foundation. With an overestimated longitudinal force in the surrounding soil, decompression zones (cracks) can occur, which can also lead to a decrease in the bearing capacity of the base of the building.

The objective of the invention is to stabilize the properties of reinforced soil foundations with subsidence, swelling, quicksand and other properties, with a change in the diameter of the roll or axial load on it.

The problem is solved by well formation, saturation of the well with crushed stone with its layer-by-layer compaction. The well can be obtained by methods of excavation, for example by auger method, or without excavation, for example by rolling. Then the bottomhole and the lower section of the well are portionwise saturated with crushed stone. The volume of each portion of the mixture is determined from the ratio:

V _{crushed stone} = (from 0.5 to 1.5) · V _stamp · k,

where V _gravel is the volume of a portion of gravel;

V _stamp - the volume of a cylindrical-conical stamp;

k is the compaction coefficient of crushed stone.

Crushed stone is compacted by immersion of a rotating conical stamp with an axial force at which the specific resistance to immersion of the cone will be in the range from 1 to 4 MPa. Axial force is calculated by the formula:

where F _axial - axial force, N;

R _beats - specific resistance to immersion of the cone in the range from 1 to 4 MPa;

d _stamp - the diameter of the cylindrical part of the stamp, m

Crushed stone is saturated to the design level, then the upper section of the well is reinforced and concreted with the formation of the pile head. Piles made by the proposed method provide a stable increase in the bearing capacity of soils due to the correspondence of the diameters of the dies to the axial loads transferred to them.

The proposed technical solution is illustrated by the drawing, where in FIG. 1 shows a structural diagram of a combined printed pile.

A method of manufacturing a carrier of a combined stuffed pile is shown on the example of drilling machines based on excavators with a mass of 18 and 36 tons with reinforcing subsidence in the depth range from 3 to 5 m. First, a drilling machine based on an 18 tons excavator passes a well with a diameter of 200 mm by auger method to a depth of 6 m. Then the screw is changed to a cylindrical-conical stamp (roll) with a diameter of 200 mm. After that, portionwise (from 30 to 40 l), 20–40 mm fractions of the bottom face and bottom section of the well are saturated with slag crushed stone. At the same time, each portion of crushed stone is compacted by immersion of a rotating stamp (rolling machine) with an axial load of 60 to 65 kN. Saturation with crushed stone is carried out to a depth of 2 m from the day surface, which requires from 8 to 12 compaction cycles. After that, the upper section of the well is concreted. When using an excavator weighing 36 tons and a stamp with a diameter of 300 mm, the axial load is increased to 120 kN and saturation with crushed stone is carried out for a period of 5 to 7 compaction cycles with a portion size of crushed stone from 100 to 130 liters.

Due to the larger diameter, the bearing capacity of the pile increases from 2 to 2.5 times. The above examples show that increasing the weight of the drilling machine by 2 times reduces the required number of piles from 2 to 2.5 times and the total complexity from 3.5 to 4 times.

Claims (1)

A method of manufacturing a carrier of a stuffed pile, combined according to the material, including the formation of a well by excavation or without excavation, filling the well with a layer-by-layer rigid loose mixture, followed by compaction of each layer, characterized in that the volume of crushed stone portions is calculated by the formula:
V _{crushed stone} = (from 0.5 to 1.5) · V _stamp · k,
where V _gravel is the volume of a portion of gravel;
V _stamp - the volume of a cylindrical-conical stamp;
k is the compaction coefficient of crushed stone;
compacted by immersion of a rotating cylindrical-conical stamp with an axial force selected from the calculation

where F _axial - axial force, N;
R _beats - specific resistance to immersion of the cone in the range from 1 to 4 MPa; d _stamp - the diameter of the cylindrical part of the stamp, m,
and saturation with crushed stone is carried out to the design level, then the upper section of the well is reinforced and concreted with the formation of the pile head.

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