RU2487215C1 - Device for formation of wells in soil by method of piercing - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: device for formation of wells in soil by the method of piercing comprises a hollow working tip of conical shape fixed on the front end of a pressure rod in direction of piercing and a feeding mechanism. In the wall of the hollow working tip there are holes, and on its outer surface there is an elastic impermeable shell fixed to the top and the base of the working tip. The inner cavity of the working tip is tightly connected to the hollow pressure rod, the other end of which is connected with a source of pulsating liquid or gas.

EFFECT: increased efficiency.

1 dwg

Description

The invention relates to construction, and in particular to devices designed for trenchless laying of hidden passages for laying pipelines, cable communication lines and power lines, as well as the formation of wells for rammed piles during the construction of foundations for buildings and structures.

A device for forming wells in the soil by a puncture method is known, comprising a conical hollow working tip mounted on the front end of the pressure rod in the direction of the puncture, and a feeding mechanism.

The disadvantage of this device is the large pressure force required for the formation of the well, which leads to loss of stability of the rod, correction of the well, limitation of the length of the puncture and additional costs for the device retaining walls and the design of pressure devices.

The purpose of the invention is the reduction of the pressure head required for the formation of the well.

To achieve this goal, holes are made in the wall of the hollow working tip, and on its outer surface there is an elastic impermeable shell fixed to the top and base of the working tip, while the internal cavity of the working tip is hermetically connected to the hollow pressure rod, the other end of which is connected to the pulsating source liquid or gas.

Figure 1 shows a general view of the device for forming wells in the soil by a puncture method. The device contains a hollow working tip 1 of a conical shape, in the walls of which holes 2 are made, an elastic impenetrable shell 3 is mounted on its outer surface, fixed to the top and base of the working tip. The working tip through a flange 4 with a hole 5 is hermetically connected to a hollow pressure rod 6, the other end of which is connected to a source of pulsating liquid or gas 7.

To form a well, the working tip 1 is installed at the desired point and, using the feed mechanism and pressure rod 6, is immersed in the ground. At the same time, the source of the pulsating liquid or gas 7 is turned on, which, with a certain frequency, delivers and returns a certain volume of the working liquid or gas through the hollow rod 6 to the inside of the hollow working tip 1, as a result of which the excess pressure of the liquid or gas through the openings 2 in the walls of the working tip 1 acts on an elastic impermeable shell 3, fixed at the top and bottom of the cone. As soon as the pressure of the liquid or gas inside the working tip exceeds the yield stress of the soil, the elastic shell displaces the soil along the entire working surface of the cone, forming a gap 5 between the housing of the working tip and the inner surface of the elastic shell. After depressurization inside the case of the working tip, the elastic shell returns to its original position, and between it and the soil there remains free space in volume equal to the volume of the displaced soil. The rod moves the working tip in the direction of the puncture of the well, introducing it into contact with the ground, and the cycle repeats.

The free movement of the working tip for one cycle of pulsation of the elastic shell will be

$$s=\frac{\delta }{tg\alpha },$$

where δ is the gap between the outer surface of the elastic shell and the surface of the conical well, equal to the deformation of the elastic shell under the action of a compressed liquid or gas; α - half the angle at the apex of the cone of the working tip.

Since tgα <tgρ, where ρ is the angle of friction between the soil and the shell, when the soil expands, the conical tip self-seizes and does not transmit the axial reaction to the rod, and the pressure force of the rod is necessary only to overcome the friction forces of the device against the well walls when moving it in the direction penetration at the time of depressurization in the working tip.

When wells are formed in soils with a non-rigid skeleton (clay, loam, water-saturated soils), the greatest effect is produced by a liquid pulsator with a low frequency and a large stroke of the shell. On soils with a rigid skeleton (sand-gravel, sandy loam), it is more efficient to use an air pulsator with a small stroke of the shell and a high pulsation frequency. This mode is similar to the vibrational effect of the shell on the soil, as a result of which there is a significant decrease in the friction and adhesion forces between the soil particles in the compaction zone, which leads to a significant reduction in the yield stresses of the soil, and therefore requires a lower pulse pressure.

The application of the proposed design of the device for the formation of wells in the soil in the form of a hollow conical working tip, the holes are made in the walls, and on its outer surface there is an elastic impenetrable shell fixed to the top and base of the working tip, while the inner blade of the working tip is hermetically connected to hollow pressure rod, the other end of which is connected to a source of pulsating liquid or gas, will significantly reduce the pressure force, necessary for formation of a well, because unlike the prototype, the well is formed by compressing the soil with a pulsating elastic impenetrable shell mounted on the outer surface of the conical working tip, and the pressure force of the rod is necessary only to overcome the friction forces of the devices on the well walls when moving it in the direction of the puncture at the time of pressure release in the working tip well walls. Reducing the pressure force, in turn, will increase the length and accuracy of the well puncture, reduce the cost of retaining walls and the design of pressure devices.

Information sources

1. S.G. Vasiliev. Closed laying of communications. - Lviv: Higher school. 1974. - S. 8.

Claims (1)

A device for forming wells in the soil by a puncture method, comprising a conical hollow working tip mounted on the front end of the pressure rod in the direction of the puncture and a feeding mechanism, characterized in that holes are made in the wall of the hollow working tip and an elastic impermeable is installed on its outer surface a shell attached to the top and base of the working tip, while the inner cavity of the working tip is hermetically connected to the hollow pressure rod, the other end of which is connected with a source of pulsating liquid or gas.

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