RU2358062C1 - Discharge switch for grouting piles - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: discharge switch for grouting piles consists of a vertical upper electrode and lower electrode containing five current-conducting elements, which are arranged at some distance from each other opposite the holes made in forming box body. To utilise hydrodynamic effect to a maximum extent, reflecting shield is fixed to the body. In order to switch low electrodes sequentially, a cable is connected to sharing selector switch. The type of electrodes is accepted in this device as "symmetrical bumpy surface - apex". It allows for producing discharges sequentially one after another. The number of electrodes corresponds to the number of holes made in forming box. The electrodes are arranged opposite to holes made in forming bob body. The number of electrodes has to be even. The axis of current-conducting element in the lower electrode is perpendicular to the working surface of the upper electrode. To achieve maximum effect of shock waves directing, the above-mentioned reflecting shield is used. The tilt angle between shield working surface and axis of current-conducting elements in the lower electrode is 45-60 degrees as quality of hydro pulse shock wave formation is used such as direction of their action.

EFFECT: reduced energy consumption, improved bearing capacity of pile.

4 cl, 2 dwg

Description

The invention relates to high-voltage equipment for creating rammed piles and can be used in the construction of pile foundations, the strengthening of soil masses in capital construction.

A device for the manufacture of bored piles (AS USSR N 774941, V28V, 1978), for compaction of concrete mixture. Such a spark gap allows you to create stuffed piles, but the main disadvantage is that it requires high costs of electrical energy.

The closest technical solution to the invention is the device described in patent 94030388, cl. 6 E02D 5/36, dated 11/28/1996, the spark gap of which can seal the walls of the well, but the cost of electric energy does not correspond to the increase in the specific bearing capacity of the pile. The fact is that the electrodes create a certain orientation to the formed factors of the electric discharge (shock wave, hydrodynamic vibrations, cavitation flows), at the same time, a significant part of the energy is spent on useful work. Practice has established that, with a well diameter of 120-450 mm, its walls expand to a diameter of 300-700 and above, depending on soil conditions (TR 50-180-06 “Technical Recommendations for the Design and Installation of Pile Foundations Used Using Discharge-Pulse technologies for high-rise buildings (RIT piles) ”). At the same time, after concrete is filled in with a zone with a disturbed soil structure (drill string), stabilization is further observed in its penetration into a denser structure. Subsequent expansion of the borehole diameter under the influence of an electric discharge occurs, however, the depth of saturation with concrete is directly proportional to the specific energy input. The energy of electrical impulses is spent on creating a density field around the well, on introducing the filling material into the soil, on compaction of the filler itself and on the formation of a bulge. At the same time, in some cases, when installing pile or other foundations, there is a need to increase the diameter of the well by 2.0 ... 2., 5 times (as indicated above), to achieve a high specific load bearing capacity of piles of the order of 120 ... 150 t, as well as uniform compaction mass of soil to the design value.

The purpose of the invention is to reduce the energy consumption of the process, increasing the bearing capacity of piles.

Figure 1, 2 shows a General view of the arrester.

The arrester for creating printed piles consists of a vertically located upper electrode 1 and a lower electrode 3, containing five conductive elements 2, which are located at a certain distance from each other opposite the holes in the housing 5 of the forming chamber. For the most complete use of the hydrodynamic effect, a reflecting screen 4 is fixed on the housing 5. For sequential switching of the lower electrodes, the cable 7 is connected to an electric step finder 6.

In this device, the type of electrodes adopted "symmetric convex surface - tip", which allows you to produce discharges sequentially one after another. The number of electrodes corresponds to the number of holes in the forming chamber. The electrodes are located opposite the holes in the body of the forming chamber, while the number of electrodes should be odd. The axis of each conductive element of the lower electrode is perpendicular to the working surface of the upper electrode.

To fully achieve the effect of the direction of shock waves, use a reflective screen, the angle of inclination between the working surface of which and the axis of the conductive elements of the lower electrode is 45-60 °, using the property of the formation of hydro-pulse shock waves, namely the direction of their action.

The radius of the base of the convex surface is 3-3.5 times smaller than the radius of the lower electrode.

The lower electrode is removable. It is fixed at the base of the camera. N.Svatovskoy found that a pair of electrodes does not require adjustment of the gap for 7000-8000 pulses. To prevent solder of conductive elements to the housing and the possibility of changing the interelectrode gap, the conductive elements are located in the dielectric sleeve.

The device operates as follows. A working body (spark gap) is lowered into a well filled with cast concrete mixture to the first working horizon, usually 300-350 mm. The process is as follows: electrical energy of alternating current of industrial frequency voltage 220-380 V (frequency 50 Hz) up to 10.0 kV, for the manufacture of piles and soil compaction. Electric power of direct current and high voltage is accumulated in the block of capacitor banks up to 60.0 kJ. Further, the accumulated energy is directed to an energy emitter (spark gap) immersed in a concrete mixture. Between the electrodes of the emitter there should always be a liquid electrolyte, such as cement mortar or concrete mix. When power is supplied to the electrodes of the emitter in the interelectrode gap, a high energy density of 1013-1014 J / m ^{3 is created} , breakdown occurs with the formation of a plasma discharge channel. In this channel, in 10 ^-4 -10 ^-5 seconds, the temperature rises to 10 ⁴ -4 × 105 ° C and the pressure reaches 10 ⁸ ÷ 3 · 10 ⁹ Pa, which ensures a high rate of expansion of the discharge channel (up to hundreds of meters per second), formation and propagation of compression waves in the environment. At this stage, the electrical energy stored in the drive is converted to the energy of hydrodynamic disturbances.

The proposed spark gap allows you to form a pile with less energy consumption. At the same time, the soil mass is evenly compacted, which affects the overall bearing capacity of the piles. The bearing capacity of piles is increased by 20-25%.

Claims (4)

1. Arrester for creating printed piles containing the upper and lower electrodes located in the forming chamber, characterized in that an electric step finder connected to the conductive cable is connected to the lower electrode containing at least three conductive elements. 2. The arrester according to claim 1, characterized in that the lower electrode contains an odd number of conductive elements. 3. The arrester according to claim 1 or 2, characterized in that the working surface of the upper electrode has a symmetrical convex shape, and the axis of each conductive element of the lower electrode is perpendicular to the working surface of the upper electrode. 4. The arrester according to claim 3, characterized in that a reflecting screen is placed in the upper part of the forming chamber, the angle of inclination between the working surface of which and the axis of the conductive elements of the lower electrode is 45-60 °.

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