Method and device for concrete mix treatment during bored pile erection

FIELD: building, particularly to create bored piles in cased wells during building and building structure foundation erection.

SUBSTANCE: method involves heating ground surrounding place of pile erection and heating concrete mix with induction heater. The concrete mix is vibratory treated in pulsed mode at the beginning of heating operation by applying electromagnetic field generated by induction heater to metal reinforcement bars, wherein high-frequency current of induction heater is subjected to low-frequency modulation. At concrete mix setting beginning the pulsed mode is changed into high-voltage one. Device for above method realization comprises induction heater comprising steel pipe put on asbestos-cement pile casing pipe and winding made of copper coiled bus linked with high-frequency power source. The winding is connected to metal pipe. Diametrical longitudinal orifices are made in the steel pipe. The power source comprises circuit providing high-frequency current modulation with low frequency.

EFFECT: possibility of simultaneous heat and vibration application to concrete mix, reduced cost of the device along with reduced number of working tools, simplified control, provision of concrete shrinkage and compaction under heating, which is performed by single device.

2 cl, 4 dwg

 

The invention relates to the construction and can be used in the manufacture of reinforced concrete bored piles in wells with casing pipe during the construction of foundations of buildings and structures.

When pouring concrete to improve the quality of piles by increasing the strength of concrete and improve its physico-chemical properties using thermal and vibration treatment, carried out simultaneously or in a mode that depends on the processing methods and the equipment used.

From the prior art known methods of treatment of concrete mixtures by vibration with odnovremenno heating electric shock (SU 1595825; EN 2132917). And warming up are using transverse and longitudinal electrodes, and vibration on the face of the tray is a mechanical vibrator. The main disadvantage of this method is the impossibility of its application in the construction at the site of erection of the piles, because of the complexity of the design for implementing the method it is intended for stationary conditions of production.

Known methods of sealing concrete mixtures in the construction of bored piles by mechanical compacting concrete after its submission in a pre-drilled hole (USA No. 2963869). This method has low productivity and requires heavy equipment is for compacting and individual equipment for heating concrete mix during the construction of piles in frozen ground.

Known methods of compaction during the construction of bored piles by creating an electrical discharge between the electrodes lowered into the well, filled with a concrete mix (EN 2090716, US 4230425, EN 2117726,) the disadvantages of the known technical solutions is the need to introduce additional equipment for heating during the construction of piles in frozen soils. In addition, even in the construction in soils with normal heating temperature of the concrete mixture accelerates the hardening and increases the strength after hardening.

The closest to the invention is a method of processing concrete mixtures in the construction of reinforced concrete piles, which consists in the induction heating of the concrete mixture by heating by eddy currents in the metal pipe, put on the casing (the"guide for the production of concrete work in winter conditions, in areas of the Far East, Siberia and the Far North), stroiizdat, 1982). The disadvantage of this method is the absence of operations for the hardening of the concrete, resulting in a mass of concrete can be air cavity, which reduces the strength of the piles.

The closest technical solution to the claimed device is an induction heater comprising a metal pipe laid on her winding of copper bus bars connected to a source of high frequency is wow power ("guide for the production of concrete work in winter conditions, in areas of the Far East, Siberia and the Far North), stroiizdat, 1982, str, 181).

A disadvantage of the known device is the lack of compaction of the concrete mixture when it is heated, which reduces the strength of the piles.

The basis of the invention is to develop a method of simultaneous exposure to the concrete mix during the construction of the piles of thermal fields and vibrational field, carry out a simple inexpensive device with a minimum amount of equipment and ease of management.

The problem is solved in that in the method of processing concrete mixtures in the construction of reinforced concrete bored piles, comprising heating the surrounding soil and concrete mixture induction heater, at the initial stage of heating the concrete mix to produce the vibration treatment in a pulsed mode by affecting metal rebar piles electromagnetic field generated by the induction heater, for which high-frequency current induction heater is subjected to low-frequency modulation, and at the beginning of setting of concrete mixtures change pulse mode at high frequency.

The device for implementing the method as a prototype, contains steel pipe, put on the asbestos-cement casing pipe piles, and a winding in the form of coils copper bus bars located on the metal is tion pipe. Unlike the prototype, the steel pipe is made diametrically opposite longitudinal window, and the power supply includes a circuit providing a modulated high-frequency current of low frequency.

The technical result of the invention is the use of mechanical influence of the electromagnetic field of the induction heater to the metal reinforcement bars in the liquid concrete with shrinkage and compaction of the concrete mixture with heating by one device.

This method allows using the same low heat concrete mixture and the vibration treatment. This significantly reduces the amount of equipment that is needed in the construction of the piles, simplifies the management process of the concrete mix, allows a wide range to vary the operations of heating and vibrating processing, using the sequence optimal for these construction conditions or for a given type of concrete mixture.

Figure 1 presents a diagram of the device for implementing this method.

Figure 2 shows the design of the pipe with Windows, front view, figure 3 is the same, left side view, figure 4 - pipe design in ISO.

A device for processing concrete mix during the construction of bored piles contains a metal pipe 1 installed on obsa the ing the pipe 2 into the pre-drilled hole 3 under the pile, containing reinforcing metal rods 4. On the surface of the pipe 1 are stacked coil of 5 turns of copper insulated bus, which ends 6 and 7 are connected by a high-frequency power source 8. In the metal pipe 1 is made of a longitudinal window 9 and 10, arranged opposite each other (Figure 2 and 3). The power source 8 includes a control circuit that provides a low frequency modulation high frequency inductor current (not shown), which may be performed by any of the known schemas.

The processing method of the concrete mixture as follows. In seasonally frozen ground 12 drill the well to a depth of seasonal freezing 11, a diameter which exceeds the diameter of the pile shaft 3. After installation of the casing 2 with a lost tip 14 in a pre-drilled hole 3, lower reinforcement cage with rods 4. On the casing is placed a coil consisting of a metal pipe 1 with a longitudinal Windows 9 and 10, and the winding 5, the ends 6 and 7 are connected with a source of high frequency power supply 8, which is a frequency Converter. The length of the inductor corresponds to the depth of the borehole 11. After that, include a power source 8 and the circuit of the low-frequency modulation of high-frequency power source. Power to the inductor at this time comes pulses with often the Oh from 50 to a few Hertz. To heat it more beneficial to use a high frequency. To resolve this contradiction, the high frequency current flowing in the tire inductor, modulate a low frequency by means of known devices. The electromagnetic field generated by current flowing through a copper bus 5 through a longitudinal window 9 and 10 acts on the rod 4 valves, pulling them. With a maximum force on the valve will operate the nearest section of the conductors. When this metal construction will stretch, and at the end of the current pulse power of elasticity returns the rod to its original position. In order fluctuations were tangible, it is necessary to act on the pile with a frequency of from 50 to a few Hertz. Vibration from the bars 4 are distributed in the liquid concrete mixture, and when this happens its compaction and shrinkage. The size of the Windows 9 and 10 in the metal tube 1 is determined by the force required to fluctuations rebar and the necessary structural strength. Studies have shown that the size of the Windows along the perimeter of the pipe is 30 to 40 percent of its perimeter and along the length of the pipe can be from 50 to 80 percent of its length. The design should be installed on the workstation so that the distance between the conductive tyres and valves was minimal. Thus, it is possible in order to achieve the greatest electromagnetic efforts to valve. When the concrete begins to set, the control system switches the power source from pulse mode to the normal mode of operation in which there is a heating of the metal pipe 1, the heat from which is fed in to the concrete and surrounding the borehole soil. The time course of the pulse mode is determined by the composition of the mixture and ambient conditions, and is set when programming the control circuit. In the process of heating piles the power supplied to the inductor, will be adjusted depending on the frequency of the operating current and from the geometric performance of the inductor and its size. After the concrete design temperature cutoff of the power source.

Thus, the proposed method and realizing it device allow the processing of the concrete mix during the construction of the piles, one simple and inexpensive device, and this simplifies the management scheme process.

1. The method of processing concrete mixtures in the construction of reinforced concrete bored piles, comprising heating the surrounding soil and concrete mixture induction heater, characterized in that at the initial stage of heating the concrete mix to produce the vibration treatment in a pulsed mode by affecting metal rebar piles electromagnetic field, generated the output of the induction heater, why high-frequency current induction heater is subjected to low-frequency modulation, and at the beginning of setting of concrete mixtures change pulse mode at high frequency.

2. The device for implementing the method according to claim 1, characterized in that it consists of an induction heater containing steel pipe, put on the asbestos-cement casing pipe piles, and a winding in the form of coils copper bus bars, connected to a source of high frequency power and located on the metal pipe, the steel pipe is made diametrically opposite longitudinal window, and the power supply includes a circuit providing a modulated high-frequency current of low frequency.



 

Same patents:

FIELD: building, particularly to erect cast-in-place pile having large diameter in collapsible ground layer of large thickness.

SUBSTANCE: method involves drilling pilot hole; installing casing pipe connected to puncher; punching the well ground by dropping load on the puncher through casing pipe to reach design point and enlarging the casing pipe; arranging reinforcement case in the pipe; filling the well with concrete mix as casing pipe moves upward; compacting the concrete mix. In the case of pile with 300-1500 mm diameter forming and in the case of collapsible ground layer thickness up to 18 m or 18-50 m ratio between pilot hole depth and collapsible ground thickness is 1:(4.5-6) and 1:(1.5-5). The puncher has reinforced concrete tip and head made of tube with outer diameter equal to inner diameter of pilot hole. Welded to the head are centering rings. The tip has ring to engage thereof with technological control rod provided with thread, washer with retainers and nut on opposite end thereof. Ratio of height H of upper head part provided with centering rings to length of casing pipe to be installed in the head is 1:(20-30). Ratio between outer puncher diameter D and outer diameter d at tapered part ℓ thereof is equal to 1:0.8. Length ratio between cylindrical head part L and cylindrical tapered part ℓ is equal to 1:0.6. Angles γ of head and head transition area leading to tapered part ℓ are equal to 30°. Difference between outer puncher diameter D to outer casing pipe T diameter is 90-100 mm.

EFFECT: reduced labor inputs and decreased material consumption.

2 dwg

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FIELD: foundation building.

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4 dwg, 1 ex

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EFFECT: reduced power inputs along with maintaining high productivity and increased load-bearing pile capacity.

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7 cl, 13 dwg

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2 cl, 13 dwg

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