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Square Rectangular Tube Beijing Square Rectangular Tube
<:> >The role of acoustic detection tube
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< < r :: .>, , ):: >（ ) The shell material is filled in the hole. The shell material is also called sealing mud. After the borehole reaches the designed depth, the sealing mud is poured from the drill. Its function is to close the gap between the one-way valve tube and the borehole, forcing the hole to flow from the grouting hole. The ring is opened, and the pressed slurry squeezes out the casing material and injects into the surrounding soil.
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< r :: .>, , ):: >() Insert a one-way valve tube (split injection injection) into a borehole filled with sealing mud The slurry pipe) is generally made of plastic pipes with an inner diameter of ~, and a group of slurry injection holes is drilled every other ~ (i.e., every meter ~ group) and wrapped with a rubber sleeve. When inserted into the drill hole, the pipe end is closed and the pipe is filled with clean water.
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< r>, , ):: >() After the sealing mud reaches a certain strength, insert a two-way sealing grouting core into the one-way valve tube The pipe is grouted in layers. First, increase the pressure to push the slurry open the rubber sleeve, squeeze out the casing material, cause splitting in the soil, and spread along the cracks. The diffusion range is affected by factors such as slurry pressure, time, slurry ratio, and soil characteristics. . Generally, grouting is done from the bottom upward. After reaching a certain pressure, lift a section and grout again, and repeat this process. After the grouting is completed, lift up a section of grout to retain the grouting for the second time (the one-way valve plastic pipe will remain in the soil layer after grouting).
>The acoustic detection tube is the channel through which the probe enters the inside of the pile body when the cast-in-place pile is subjected to ultrasonic testing. It is an important part of the cast-in-place pile ultrasonic detection system. Its pre-embedding method in the pile and its layout on the cross-section of the pile will directly affect the detection results. Therefore, the layout and embedding method of the acoustic tubes should be marked on the drawings when designing the piles to be inspected, and the quality of embedding should be strictly controlled during construction to ensure the smooth progress of the inspection work.
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>< >. Selection of acoustic tube
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> The choice of acoustic tube material is based on the sound transmittance. The principles are large, easy to install and low cost.
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> The acoustic pulse is emitted from the transmitting transducer, reaches the interface between the water and the acoustic pipe wall through the coupled water, and then passes through the pipe wall to the interface between the acoustic pipe wall and the concrete, passing through The concrete then needs to pass through two interfaces of another acoustic tube to reach the receiving transducer.
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> Therefore, the acoustic tube forms < r>< > interfaces, and the sound energy transmission coefficient of each interface can be calculated as follows:
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> ( < r>< >) In the formula: < r>< >The sound energy transmission coefficient of a certain interface
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> < r>< >The acoustic impedance rate of the medium on both sides of the interface< r>()
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> The total sound transmission coefficient of the < r>< > interface between the transmitting and receiving transducers is
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> (< r>< >) currently commonly used The pipes include steel pipes, steel corrugated pipes, and plastic pipes.
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> The advantage of steel pipe is that it is easy to install. It can be welded to the steel frame by electric welding, which can replace part of the steel bar section. Moreover, the steel pipe has high stiffness. After embedding, its parallelism and straightness can be basically maintained. Currently, many large-diameter cast-in-place piles use steel as the acoustic tube. However, the price of steel pipes is more expensive:
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> Steel corrugated pipes are a better material for acoustic detection pipes. They have thin pipe walls, less steel and are impermeable, pressure resistant, high strength, It has good flexibility and other characteristics, and is usually used to reserve holes for post-tensioning in prestressed structures: when used as acoustic tubes. It can be tied directly to the steel frame soil, and the joints can be connected with one size larger corrugated socket. Because the bellows is very light, it is very easy to operate, but care must be taken to keep its axis straight during installation.
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