JPH026886B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for destroying pile heads that can be easily destroyed by systematically generating cracks in the concrete portion of the pile head of cast-in-place concrete piles. It is about the method.

[Prior art] Traditionally, the main method for destroying pile head reinforcement concrete of cast-in-place concrete piles has been manual methods using picks, etc. A method of destroying the material by burying it in advance at the location where it is planned to be cut and filling it with a slurry of an expandable crushing agent
204216, Japanese Patent Application Laid-open No. 59-91214), etc.

[Problems to be Solved by the Invention] Among these methods, the manual method using a pick etc. generates significant noise and dust.
In urban areas, it causes pollution and also poses safety and health problems for workers.

The method of filling a slurry of expandable crushing agent can suppress the generation of noise and dust, but it is necessary to maintain the fluidity of the slurry constant during operation, which makes it difficult to control the amount of water and kneading work. The work is complicated as it needs to be done thoroughly.

Therefore, there is a need for a method for crushing the pile head of cast-in-place concrete using an expansive crushing agent that does not involve complicated management of water volume or mixing of the crushing agent, and the present invention is directed to such a method. The purpose of the present invention is to provide a method for destroying cast-in-place concrete pile caps that solves the drawbacks of conventional methods.

[Means for Solving the Problems] This invention solves the above-mentioned problems by filling a pipe with a large number of small holes for water permeation with a powdered or granular static crushing agent at the boundary line of the fractured pile head. This problem can be solved by installing the piles so as to almost surround the inside of the outer periphery of the piles.

That is, this invention installs a pipe filled with a static crushing agent in the form of powder or granules so as to substantially surround the inside of the outer periphery of the pile along the boundary line of the fractured part of the pile head of cast-in-place concrete, and casts concrete. After the pile is installed, excess water in the concrete is absorbed through small permeable holes previously provided in the pipe, and the static crushing agent in the pipe reacts and develops expansion pressure, causing the pile cap to fail. This is a method of destroying cast-in-place concrete pile heads, which is characterized by destroying them.

[Function] To carry out this invention, first, a pipe (for example, a spiral sheath pipe) is filled with a static crushing agent (for example, Onoda Cement registered trademark Blyster), and then the pipe is connected to reinforcing bars as shown in FIG. The reinforced concrete pile of the concrete pile with the cage is attached to the inside of the reinforcing bar cage along or slightly above the scheduled cutting line with a binding wire, and after this reinforcing bar cage is set in position, ready-mixed concrete is poured and concrete is made. Form a pile. At this time, the surface of the reinforcing bars above the planned concrete cutting line is covered with vinyl or plastic to make it easier to separate from the concrete. Through small permeable holes in pre-installed pipes completely buried in the concrete,
Excess water in the concrete is supplied to the static crushing agent filled inside the pipe, causing a hydration reaction, which generates expansion pressure and allows cracks to occur in planned cut lines of pile caps. It is preferable to install the pipe approximately 5 to 10 cm above the planned cutting line of the excess concrete, depending on the diameter of the reinforcing bar cage.

As the static crushing agent used in this invention, in addition to the above-mentioned Blister, various known commercially available static crushing agents in the form of general powders and granules can be used.
It is desirable that the composition be adjusted with a retardant or the like to correspond to the strength development time of concrete, and the expansion pressure development time should be adjusted.

PC sheath pipes are suitable as pipes, but
Various other materials such as plastics having similar strength can be used. The diameter of the pipe is
30-60mm is suitable. The holes for water permeation provided in the pipe should be φ0.5~, taking into account the prevention of powder outflow and water permeability.
2.5 m/m, preferably φ1.0 to 1.5 m/m.
The number of holes is preferably 1 to 10 holes, preferably 4 to 6 holes per cm ² of pipe. A hole for water permeation is provided in Figure 1.
The perspective view of the sheath tube for PC is shown.

To fill a pipe with a static crushing agent, for example, the pipe is made into a semicircular shape, one end is closed, a predetermined amount of crushing agent is filled, the other end is closed, and the pipe is installed in a circular shape at a predetermined position. The pipe may be further divided and installed in the same manner. Further, if necessary, the concrete may be divided and crushed by connecting a plurality of pipes filled with a static crushing agent to a reinforcing bar cage and installing them in the vertical direction.

The amount of water supplied from concrete can be adjusted by the diameter and number of holes drilled in the sheath pipe, and can be made approximately equal to the amount required for the hydration reaction of the static crushing agent. Outflow can also be almost completely prevented.

[Example] The present invention will be explained below based on Examples.

Example 1 A PC sheath pipe with a diameter of 40 m/m and a wall thickness of 0.3 m/m was provided with 5 holes of 1 m/m in diameter per ¹ cm2, and this was cut approximately equal to the length of the circumference of the reinforcing bar cage to form a semicircular shape. Close one end, fill it with powdered blister, which is a static crushing agent, until it is full and cover it with a lid. At this time, there is no need to perform vibration, tamping, compaction, etc., and it is sufficient to simply pour the material naturally. Next, this is attached to the inside of the reinforcing bar cage with a binding wire along the cutting line of the pile head of a φ1200m/m pile.

Blister develops expansion pressure in line with the strength development of concrete, and the development of expansion pressure is 0 Kg/cm 2 in 1 day, and 0 kg/cm ² in 4 days.
100Kg/cm ² and 180Kg/cm ² after 5 days were used.
When excavation was carried out 7 days after concrete was poured, a width of 3 to 5 m/m was found along the planned cutting line.
A crack occurred and the head of the pile was able to be severed.

Example 2 A PC sheath pipe with a diameter of 40 m/m and a wall thickness of 0.3 m/m was provided with 3 holes of 2.5 m/m in diameter per ¹ cm2, and this was cut approximately equal to the length of the circumference of the reinforcing bar cage. , fill it with granular blister, which is a static crushing agent, and put a lid on it. This is attached to the inside of the reinforcing bar cage with a binding wire along the cutting line of the pile head of a φ1000m/m bed pile.

Granular Blister has a particle size range of 0.3m/m~
5.0 m/m and a bulk specific gravity of 2.0 to 2.7, and the development of expansion pressure is 0 Kg/cm ² at 1 day of age, 100 Kg/cm ² at 4 days,
180Kg/cm ² was used in 5 days. When excavation was carried out 7 days after concrete was placed, a crack with a width of 2 to 4 m/m occurred along the cutting line, and the pile head was able to be severed.

Example 3 A resin pipe with a diameter of 40 m/m and a wall thickness of 0.5 m/m is provided with 5 holes of 1 m/m in diameter per ¹ cm2, and the length is approximately equal to the circumference of the reinforcing bar cage to form a circular shape.
Close one side and check the particle size distribution using a JIS standard sieve.
Fill with sintered compacts for static crushing that have been coarsely crushed and classified to 1.2m/m all through, 65% remaining at 0.6m/m, and 90% remaining at 0.3m/m, and cover with a lid. Next, attach this to a cast-in-place concrete pile with a diameter of 1200 m/m along the planned cutting line of the pile head with a binding wire.

Next, ready-mixed concrete is poured to form the piles. Excess water in the concrete permeates through the small holes for water permeation, and the expansion pressure is increased to 15 kg / 1 day after the material ages.
cm ² , 100 Kg/cm ² after 3 days, and 150 Kg/cm ² after 5 days. When the piles were dug 10 days later,
A crack with a width of 3 to 5 m/m occurred along the planned cutting line, and the pile cap was severed.

When this sintered body for static crushing is used, surplus water in the concrete is supplied through the small holes for water permeation immediately after concrete is placed, and the hydration reaction begins. The rate of water penetration is slower than that in concrete, and expansion pressure develops in parallel with the development of concrete strength, making it possible to systematically create cracks on the planned cutting line of the pile cap.

[Effect of the invention] According to this invention, a static crushing agent in the form of powder or granules is used, and expansion pressure is generated by reacting the crushing agent with excess water in the concrete. No management required, easy to operate,
It is possible to statically and systematically destroy the excess concrete of the pile cap.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a PC sheath tube used in carrying out the present invention, and FIG.
It is a perspective view when the PC sheath pipe is attached to the inside of the reinforcing bar cage. In the figure, 1...PC sheath pipe, 2...hole, 3...reinforced cage. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 Along the boundary line of the failed pile head of cast-in-place concrete, almost encircling the inside of the reinforcing bars on the outer periphery of the pile,
After installing a pipe filled with a powder or granular static crushing agent and pouring concrete, the excess water in the concrete is absorbed through small permeable holes prepared in the pipe in advance. A method for destroying a cast-in-place concrete pile cap, characterized in that a static crushing agent reacts and develops expansion pressure to destroy the pile cap destruction portion.