Acoustic logging tube is an indispensable acoustic detection tube at present, which can be used to detect the quality of piles and is the channel for probes to enter the pile body when ultrasonic testing is carried out on cast-in-place piles. It is an important part of ultrasonic testing system for cast-in-place piles, and its embedding mode and arrangement on pile section will directly affect the testing results. Therefore, when designing the pile to be tested, the layout and embedding method of acoustic pipes should be marked on the drawings, and the embedding quality and pipe wall thickness should be strictly controlled during construction to ensure the smooth detection. Basic information
Text name; The name of the acoustic pipe; Acoustic logging tube representation; Acoustic detection of embedded pipeline range; Bridge pile foundation detection
catalogue
1 purchase
2 structure
3 installation
Four uses
5 cases
6 Treatment method of pipeline blockage
7 ultrasonic testing
8 Introduction of process principle
9 Installation quality control
10 FAQ
1 1 solution
12 specifications and models
Selection and purchase
The choice of sound tube material is based on the principle of high sound transmittance, convenient installation and low cost.
The sound pulse is emitted from the transmitting transducer, reaches the interface between water and the wall of the sound tube through the coupled water, then reaches the interface between the wall of the sound tube and concrete through the wall, and then reaches the receiving transducer through two interfaces of another sound tube.
Therefore, the sound tube forms four interfaces, and the acoustic energy transfer coefficient of each interface can be calculated according to the following formula:
—— Acoustic energy transmission coefficient of the interface;
-Acoustic impedance of the medium on both sides of the interface
The total sound transmission coefficient of the four interfaces between the transmitting and receiving transducers is
The acoustic impedance is low, so it can be used as an acoustic measuring tube with high acoustic transmittance, and it can usually be used for small cast-in-place piles. Be careful when using it in large-scale cast-in-place piles, because large-diameter piles need to be poured with a lot of concrete, and the hydration heat of cement is not easy to dissipate. In view of the great difference in thermal expansion coefficient between plastic and concrete, plastic pipes contract radially and longitudinally due to temperature drop after concrete solidification, which may lead to partial separation from concrete and air or water cracks. More interfaces with strong reflection are added to the acoustic path.
The diameter of sound tube is usually larger than that of radial transducer 10mm, and the commonly used specification is 50-60mm inner diameter. The wall thickness of the pipeline has little influence on the sound transmission rate, so there is no limit on the wall thickness in principle, but from the point of view of saving steel consumption, as long as the wall can bear the lateral pressure of newly poured concrete, the thinner it is, the more economical it is.
structure
Acoustic pipes can be directly fixed on the inside of the reinforcing cage: the fixing method can be welding or binding, and the pipes should be basically parallel-if the test results need to evaluate the strength of concrete at each measuring point, the non-parallelism should be controlled below 1‰. When the reinforcing cage is put into the pile hole, it should be prevented from twisting. [1] General pipes shall be installed in sections with reinforcing cages. The joints between sections can adopt reverse thread sleeve interface or sleeve welding scheme. If corrugated pipe is used, it can be covered with larger corrugated pipe, and both ends of the sleeve are wrapped and sealed with adhesive tape. No matter which joint scheme is adopted, it is necessary to ensure no slurry leakage under high hydrostatic pressure, and the inner wall of the joint should be kept flat, and there should be no protrusions such as welding slag and burr, so as not to hinder the free movement of the probe. The bottom of the acoustic pipe should also be sealed, and the top of the pipe should be plugged with a cork after installation, so as to avoid falling into foreign bodies when pouring concrete and causing channel blockage. [2] Install a) socket joint of steel pipe; B) Socket joint of corrugated pipe
1- steel bar; 2- sound tube; 3- casing; 4- stirrup; 5- Sealing tape
Embedding device
The number of buried acoustic pipes and their arrangement in pile section should consider the control area of detection. There is usually an arrangement as shown in Figure 7, in which the shaded area is the control area for detection.
Generally, when the pile diameter is not more than 0.8m, two piles are arranged along the diameter; When the pile diameter is more than 0.8m and not more than 1.6m, the three piles are arranged in an equilateral triangle. When the pile diameter is greater than 1.6m, the four piles are arranged in a square shape.
use
Other uses of sound tube
In addition to being used as a detection channel and replacing a part of the steel bar section, the acoustic pipe can also be used as a pipe for grouting at the bottom of the pile. The test shows that the bearing capacity of cast-in-place pile treated with bottom slurry can be greatly improved. At the same time, the acoustic pipe can also be used as a pipeline for washing and grouting accident pile defects. At this time, measures should be taken to punch through the pipeline at the defective parts that need grouting.
The general requirements of ultrasonic transmission method are: the joint is firm and does not fall off, and the seal does not leak slurry; The pipe wall shall be flat and free from damage, smoothness and deformation; The pipe body is vertical and not skewed; There is no foreign body in the tube.
When the material or installation process of the acoustic pipe is poor, it may cause slurry leakage, pipe plugging, fracture, bending, sinking and deformation, which has a great influence on the ultrasonic transmission method to detect the integrity of pile foundation, and even can not be detected by ultrasonic transmission method.
situation
Based on the above situation, through the corresponding theoretical calculation and a lot of engineering practice, we developed a high-strength double-sealed hydraulic acoustic tube.
The socket end of the high-strength double-seal hydraulic acoustic sounding pipe is designed with two convex grooves, and sealing rings are installed in the convex grooves. When installing, insert the socket end of the acoustic sounding pipe into the socket end of 10cm, and then squeeze the two convex grooves at the same time with a special hydraulic clamp, so that the pipe at the squeezed position shrinks and deforms after being stressed, and the outer pipe between the two convex grooves is deeply immersed in the inner pipe, effectively realizing the reliable connection of the acoustic sounding pipe; At the same time, the rubber sealing ring is deformed and stuck between the two layers of pipes after being squeezed, which plays an excellent double-safety sealing role.
The advantage of high-strength double-sealed hydraulic sound tube is that all the elements involved in the use of sound tube are fully considered, and it has reached the leading performance in China and even in the world from all aspects.
Connection reliability
Torque resistance performance
Socket length
The internal pressure was 65438±0 MPa, and the holding pressure was 65438±0min.
The external pressure was 4mpa, and the holding pressure was 65438±0min.
It can bear the torque of120n m ≥ 8 mm and the tensile force of 3KN at the joint. The joint pressure shall be kept at 2mpa 65438 0 minutes.
4mpa holding pressure for 2 minutes.
The joint can bear 6KN tensile force.
The joint can bear the torque of180n m.
≥ 10/0mm
Excellent sealing performance.
The performance is quite stable and excellent, effectively avoiding collision with catheter and vibrator.
Full-plug connection and socket connection can ensure smooth connection.
In addition to the above leading performance, the high-strength double-sealed hydraulic sound tube also has two other obvious advantages and a set of strict safeguard measures.
Two advantages are convenience and economy.
The acoustic control tube is easy to use, which can completely avoid on-site welding, threading or slotting operations, and can be easily completed by manual operation only by using the matching hydraulic tools without power assistance, saving time and labor, and the installation is successful at one time.
Compared with the conventional φ57×3.5mm steel pipe, it can save more than 2/3 of steel and obviously reduce the material cost. As the simplest sound tube product in China, it can save the biggest labor cost in all aspects and obviously improve the work efficiency; Among the thin-walled sound pipes with various connection modes, the sound pipe can be sawed at any length according to the needs of the site, so there is no waste of short pipes and material heads, and the actual total cost is obviously reduced.
Generally speaking, there are two specifications of sound tube, one is straight sound tube and the other is clamp sound tube. The price difference between the two is mainly in the joints, and there is little difference in other aspects. Generally, it is a steel pipe with a length of 6 meters and an inner diameter of 50 mm, and the wall thickness varies according to the depth of different pile foundations.
The main parts of the sound tube
The acoustic pipe is mainly composed of four parts: bottom pipe, middle pipe, connecting pipe and dust cover (for sealing). One pipe is 6m long, and multiple intermediate pipes and joint pipes can be added according to the depth of pile foundation. Generally, a pipe (6m) is equipped with a joint pipe, and the pile foundation is equipped with 2-4 dust covers (3 for most). One end of the bottom pipe is closed and the other end is open; The middle tube is a hollow tube with two open ends.
Cost economy:
In the construction of bored piles in high-rise buildings of deep-water bridges and docks, it is required to detect the quality of pile foundation by acoustic wave transmission method, and to bury detection pipes (acoustic wave detection pipes) according to the design requirements. When the pile diameter is less than 0.8m, two detection pipes should be buried, and the two detection pipes should be fixed on the same straight line in the reinforcing cage. For piles with a diameter of 0.8m-2.0m, three detection pipes need to be buried, and the detection pipes must be fixed in a reinforcing cage in an isosceles triangle. When it is more than 2.0m, four detection tubes shall be buried and fixed in a square reinforcing cage. Conventionally, steel pipes with an outer diameter of 50-60mm and a wall thickness of about 3.5mm are required, and field welding is adopted in the construction. This method has high cost and complicated construction operation, which brings great inconvenience to on-site construction. The construction cost only accounts for about 1/3 of the cost of ordinary welded pipes. The work efficiency is greatly improved and the construction cost is reduced.
Second, the operation is simple:
Because of the high welding technical requirements of sound tube, professional welding personnel are needed. In order to ensure the quality of pile foundation concrete, there is a time limit during pile foundation grouting. In the process of reinforcing cage docking, it is necessary to weld the welded detection tube, which increases the construction risk of drilling and grouting. The sound tube produced by our company only needs to be inserted into the lower tube during the installation process, and then slightly fastened with simple tools. Welding, electricity and any technology are not needed, which greatly saves the construction time, avoids the risks caused by long-term installation and greatly improves the work efficiency.
3. Reliable quality:
When pouring concrete into the pile foundation, the requirements for the sealing, impermeability, tensile strength, torsion resistance and compression resistance of the acoustic pipe are particularly strict. A little carelessness in production and installation will cause pipe blockage, water leakage or pipe deformation, and pile foundation inspection cannot be completed. In-situ welding can not detect the sealing performance of pipe wall, joint and bottom head of pipeline, and it is difficult to guarantee the leakage resistance. The audio tubes produced by our company are strictly controlled by special personnel from the procurement of raw materials, and have been tested many times before and after production. After the product is formed, it needs to go through three testing procedures: initial inspection, gas inspection and water inspection. Ensure that the qualified rate of products is 100%, thus ensuring the requirements of pile foundation quality inspection.
4. After-sales service:
Once the products are sold, we have established an alliance and cooperative relationship with your company. After the products enter the construction site, we will send professional and technical personnel for on-site guidance, and the company will set up a 24-hour response system to solve the problems in the use process in the shortest time.
5. Transportation and storage:
Acoustic pipes can be transported by cars, trains, ships, etc. Fiber slings should be used when loading and unloading, and care should be taken to handle them with care, and no heavy objects can be pressed above them. Handle with care during construction and installation. The finished products should be placed in a dry place in the warehouse or shed, and should not be in direct contact with the ground. Sleepers should be placed under the acoustic tube. If there is no indoor warehouse, the acoustic pipes must be covered with effective objects such as tarpaulins or plastic sheets to avoid rain and rust from affecting the construction [3].
Pipe plugging treatment method
1. The determined detection scheme shall not be changed in principle.
2. "Pipe blocking": When the acoustic pipe is blocked, the construction unit should take effective measures to "block the pipe", and the following three methods can be adopted:
(1) poke the pipe with thick steel pipe;
(2) washing pigging with high-pressure water;
(3) Sweep holes with a drill bit with a small drill bit.
3. When it is impossible to "manage", it shall be handled according to the following principles:
(1), when the first pile is completed, a core-pulling test must be conducted.
(2), when the bridge is not the first pile, the construction unit according to the schedule 1 format to fill in the "change detection method application form", and signed by the supervision, the owner's representative and supervision director, before implementation.
(3) If the bridge pipe is blocked for many times, it must be tested by core-pulling in time.
4. The increased testing cost shall be borne by the construction unit.
[4] 5. The supervisor shall require the construction unit to inspect the acoustic pipe before applying for testing; When the detection scheme needs to be changed, the relevant procedures should be improved in advance to avoid the smooth construction due to the detection problems of the acoustic tube.
Ultrasonic testing/inspection
After the installation of the acoustic pipe, according to the different arrangement of the ultrasonic transducer channels in the pile, there are three main methods to detect the foundation pile by ultrasonic transmission method:
(A) in-pile cross-hole transmission method
This method is a mature and reliable method, and it is the most important form of ultrasonic transmission method to detect pile quality. The method is to bury two or more acoustic pipes in the pile, fill them with clear water, and put the transmitting and receiving transducers in the two pipes respectively. During detection, ultrasonic waves are emitted from the transmitting transducer, pass through the concrete between the two tubes, and are received by the receiving transducer. The actual effective detection range is the area swept by the sound pulse from the transmitting transducer to the receiving transducer. According to different situations, one or more detection methods are used to collect acoustic parameters, and the strength and quality of pile concrete are judged according to the change of waveform. According to the change of the relative elevation of the two transducers, the cross-hole method can be divided into horizontal measurement, oblique measurement, cross-oblique measurement, sector scanning measurement and other methods, which can be used flexibly according to actual needs. [5]
(2) Single-hole transmission method in pile
In some special cases, only one hole can be used for testing. For example, after drilling and coring, it is necessary to further understand the concrete quality around the core sample as an auxiliary means of core sample detection. At this time, the single hole test method can be used. At this time, the transducer is placed in a hole and separated by sound insulation material (or a special transducer for two receivers of an engine). The ultrasonic wave starts from the transmitting transducer, enters the concrete surface of the hole wall through the coupled water, then slides along the concrete surface for a certain distance, and then reaches the two receiving transducers respectively through the coupled water, so as to measure the acoustic parameters of the ultrasonic wave propagating along the concrete of the hole wall. It should be noted that when using this detection method, signal analysis technology must be used to eliminate the influence and interference in the pipeline. When there is a steel casing in the hole, this method cannot be adopted because the steel pipe affects the bypass of ultrasonic wave in the concrete of the hole wall.
(3) Pile hole transmission method
When the superstructure of the pile has been built or there is no sensor channel in the pile, a hole can be drilled in the soil near the edge of the pile as a detection channel. When testing, a plane transducer with high transmitting power is placed on the top surface of the pile, and the receiving transducer is slowly lowered from the hole outside the pile from top to bottom. The ultrasonic wave propagates downward along the concrete of the pile, passes through the soil layer between the pile and the hole, enters the receiving transducer through the coupled water in the hole, measures the acoustic parameters of the transmitted ultrasonic wave point by point, and roughly judges the quality of the pile according to the change of the signal. Due to the rapid attenuation of ultrasonic wave in soil, the pile length measured by this method is very limited, and only interlayer, broken pile and necking can be judged.
Introduction of process principle
Briefly introduce process control and congestion emergency plan.
Bored cast-in-place pile is an important form of foundation pile in the field of engineering construction, and its quality directly affects the safety of structure. Ultrasonic method is the most effective and accurate method to detect the integrity of pile body at present, and the embedding of acoustic tube determines whether the ultrasonic method can be carried out smoothly, so how to strengthen the quality control of acoustic tube is becoming more and more important. This paper expounds the measures for strengthening the quality control of acoustic sounding pipe, so as to ensure the smooth progress of foundation pile detection and the engineering quality.
With the expansion of investment in national infrastructure construction and the development of construction, pile foundation has become an important foundation form, which is widely used in high-rise buildings, heavy factories, bridges, ports, docks, offshore oil platforms, nuclear power plant projects and foundation treatment in earthquake areas, soft soil areas, collapsible loess areas, expansive soil areas and frozen soil areas. Bored cast-in-place pile has the advantages of low noise, less steel consumption and simple technology, and is widely used in pile foundation construction, especially for high-bearing piles and large-diameter ultra-deep piles or piles formed under complex geological conditions and unfavorable environmental conditions, which is irreplaceable by other pile types. However, the quality of bored pile is affected by many factors, such as geological conditions, pile-forming technology, machinery and equipment, construction personnel and management level. It is easy to produce quality defects such as mud inclusion, fracture, necking, concrete segregation, thick sediment at the bottom of the pile, poor density of concrete at the top of the pile, which endangers the normal use and safety of the main structure and even leads to engineering quality accidents. Because the construction of bored pile is a concealed project, it is impossible to check its quality from the appearance, and its quality directly affects the safety of the superstructure. Therefore, pile foundation detection is an indispensable link in the whole pile foundation engineering. Only by improving the quality of pile foundation inspection and the reliability of inspection and evaluation results can the quality and safety of pile foundation engineering be truly guaranteed.
1 ultrasonic testing principle
The commonly used dynamic testing methods of foundation piles include low strain reflected wave method, high strain dynamic testing method, ultrasonic method and dynamic testing method. Ultrasonic testing of foundation piles is getting more and more attention because of its high detection accuracy, no limitation of pile length and diameter, and no blind spot in detection. The detection principle is that for the foundation piles whose quality is detected by ultrasonic method, acoustic pipes are buried in the piles during construction. During detection, the transmitting transducer and the receiving transducer are placed in two pipes respectively. Starting from the bottom of the sound tube, the transmitting probe rises in one sound tube and emits high-frequency signals, which pass through the concrete and are detected by the receiving transducer moving synchronously in the other sound tube. When the probe is lifted along the whole pile length, the ultrasonic pulse of each measuring point passes through the concrete between the two pipes in turn. By measuring the relative changes of parameters such as acoustic time, amplitude and frequency of ultrasonic wave propagating in concrete medium, the defect position and influence degree of concrete between acoustic pipes are detected, and the integrity category of pile body is judged. Concrete is a heterogeneous body composed of many materials. For ordinary concrete, the speed of sound wave propagation in it has a certain range. When the propagation path encounters cracks, cracks, mud inclusion, poor compactness and other defects in concrete, the sound wave will bypass the defects or pass through the medium with slow propagation speed, so that the sound wave will be attenuated, thus prolonging the propagation time, increasing the sound wave time, reducing the calculated sound speed, reducing the amplitude and distorting the waveform. The changes of these acoustic parameters of ultrasonic wave propagation in concrete will be used for analysis and judgment. This detection method is more accurate and reliable in the integrity evaluation of bridge foundation piles, and its detection results can guide the treatment measures of defective parts.
2. The influence of sound tube on detection
During normal inspection, the following quality problems appear in the acoustic tube:
2. 1 Bending of acoustic pipe at pile bottom
Due to improper construction, the acoustic tube at the bottom of the pile bends inward and the spacing becomes smaller, which makes the transmitting and receiving transducers non-parallel, the ultrasonic pulse speed is abnormally high, the amplitude is reduced and the sound speed curve is abnormal. Because the pile bottom is a place where defects are easy to occur, it is difficult to judge whether there are defects at the pile bottom according to this curve, and it is likely that there will be missed judgments and misjudgments, leaving hidden dangers for the project.
2.2 Tilting or bending deformation of pile acoustic tube
The sound tube is not firmly bound or the binding spacing is too large. In the process of concrete pouring, the acoustic pipes are inclined or bent due to the extrusion of concrete, and the distance between the pipes becomes larger or smaller, which directly affects the analysis and judgment of the test results, and even can not give the integrity category of the pile body. Only core drilling or other reliable methods can be used for detection, which affects normal construction.
2.3 The casing at the sound pipe joint is too long.
Because the steel casing is too long and the welding quality is good, the air sealed in it can't be exhausted, and the acoustic signal can't be received until it bypasses a certain distance or passes through the air layer, which causes serious abnormality of the acoustic signal and affects the judgment of pile integrity.
2.4 The diameter of the acoustic tube is too large.
Generally, it is assumed that the transducer is located in the center of the sound tube. If the diameter of the sound tube is large, the swing range of the transducer in the tube is large, which increases the delay of coupling the water layer and has a great influence on the propagation time and detection results of sound waves.
3. Material quality control of sound tube
The material quality control of sound tube is mainly controlled from two aspects: appearance quality and material requirements.
3. 1 Appearance requirements of sound tube
The acoustic tube should be straight and bend no more than 5 mm/m; The cross section of both ends of the sound tube should be perpendicular to its axis, and there should be no burr; No cracks, scars, folding, delamination or lap welding defects are allowed; There should be no foreign body in the test tube.
3.2 Material requirements of sound tube
It is required to have sufficient mechanical strength, ensure that it will not deform during concrete pouring, and be well bonded with concrete, so as to avoid cracks between the acoustic pipe and concrete and affect the test results. Its mechanical properties, bending resistance, flattening resistance and sealing pressure resistance should meet the requirements of the specification.
The advantage of steel thin-walled acoustic tube is that it is easy to install, and it can be directly fixed on the inside of the reinforcing cage, and the fixing method can be welding or binding; Steel pipe is rigid, and its parallelism and straightness can be basically improved after being buried underground. Therefore, it is recommended to use steel thin-walled acoustic pipe for general concrete pouring piles.
3.3 Handling and storage requirements
In the process of loading and unloading the acoustic pipe, the acoustic pipe should be hoisted and transported to the designated place by mechanical or manual means, and it is forbidden to throw and roll to prevent the acoustic pipe from being deformed and bent. When hoisting, use fiber lifting belt and pay attention to handle it with care, and don't land on your head to prevent mud from blocking the acoustic pipe. When the acoustic pipe is stored in the construction site, it should be placed in the warehouse or shed to prevent rusting in the rain. When stacking outdoors, it should be stored in a dry place, with sleepers under it, heavy objects on it, and rainproof and moistureproof. Storage time shall not exceed one month.
Process quality control of 4 sound tubes
4. 1 number of embedded sound tubes
The number of acoustic pipes buried is slightly different from the traffic and building codes. The Technical Specification for Dynamic Testing of Foundation Piles in Highway Engineering of the Ministry of Communications stipulates that it is table 1.
4.2 Sound tube diameter
Generally, the diameter of the transducer put into the ultrasonic detection tube is about 30 mm or less, and the specification stipulates that the inner diameter of the ultrasonic detection tube should be larger than the diameter of the transducer 10 mm~20 mm, so the steel tube with a diameter of 40 mm~60 mm should be selected.
4.3 Wall thickness of sound tube
The wall thickness of the sound tube should not only meet the technological performance, but also ensure the safe use, and should meet the requirements in Table 2.
Installation quality control
The general requirements of ultrasonic testing for acoustic tube are: the joint is firm and does not fall off, and the seal does not leak slurry; The pipe wall shall be flat and free from damage, smoothness and deformation; The pipe body is vertical and not skewed; There is no foreign body in the tube.
5. 1 embedding
The buried depth of the acoustic pipe should be buried to the bottom of the cast-in-place pile, and its upper end should be 300 mm~500 mm higher than the top surface of the cast-in-place pile, and the exposed height of the acoustic pipe of the same pile should be the same.
5.2 sealing
Welded blind cover or steel plate should be used at the bottom of the sound tube to ensure that the seal does not leak slurry; After the installation of the acoustic pipe, the top of the pipe should be sealed with a cover or plug to avoid falling into foreign objects and blocking the passage when pouring concrete.
5.3 fixation
The acoustic pipe can be directly fixed on the inside of the reinforcing cage by spot welding or wire binding, and the spacing of the fixed points is generally not more than 2 m, among which the fixed points should be set at the bottom and joint of the acoustic pipe. For the parts without reinforcement cage, the acoustic tube can be fixed with reinforcement bracket. In order to ensure that the sound pipes are parallel to each other, triangular steel frame supports can be spot-welded between the sound pipes.
5.4 connection
When the reinforcing cage is put into the pile hole, deformation should be prevented, and the acoustic pipe is generally installed in sections with the reinforcing cage. Fix the sound tube with the bottom cover on the first reinforcement cage, and temporarily fix the rest on the prepared reinforcement cage to be lowered. When lowering the reinforcing cage, connect the upper section of the acoustic pipe and plug it in, and at the same time, tie the acoustic pipe to the reinforcing cage in turn. The joints between sections can adopt reverse thread sleeve joint or sleeve welding scheme, and the reverse thread sleeve joint should adopt soft rubber sealing ring. For sleeve connection, a steel sleeve with a length of about 80 mm can be selected, and the inner diameter is slightly larger than the outer diameter of the sound tube. The two sound tubes are sleeved and welded with the upper and lower ends of the sound tubes by electric welding. No matter which joint scheme is adopted, it is necessary to ensure that the joint has enough strength to ensure that the sound tube will not bend and fall off. Under high hydrostatic pressure, the connection parts should be dense, without slurry leakage, and the inner wall of the interface should be smooth, without welding slag and burr, which will not hinder the free movement of the transducer. If the acoustic tube needs to be cut off, it should be cut off with a cutting machine. After cutting, the nozzle should be polished to eliminate internal and external burrs, and it is not suitable to burn by electric welding. When welding steel bars, avoid splashing welding liquid on the pipe body or joint.
5.5 water injection
Every time a section is buried, clean water should be injected into the sound tube as a coupling agent for detection. River water can't be used directly, especially in flood season, when the mud content of river water is high, only purified water can be used to fill the acoustic pipe to prevent the bottom of the acoustic pipe from being blocked. Before pouring the underwater concrete of foundation piles, the water level in the acoustic pipe should be checked. If there is not enough water in the pipe, it should be replenished.
5.6 temptation
The concrete age of pile foundation can only be tested after14 d. Before testing, the pile head should be chiseled to the design elevation, and a steel bar with a length of 32mm and a length of about 20 cm should be tied with a measuring rope as a hanging hammer to test whether the acoustic pipe is unblocked and filled with clear water.
6. Emergency plan for acoustic pipe blockage
In the process of foundation pile detection, it was found that some construction units did not pay enough attention to the protection of the acoustic pipe of foundation pile, and the acoustic pipe was often blocked, which led to the failure of the detection department to carry out the detection work according to the established detection scheme and the project could not be carried out smoothly.
FREQUENTLY ASKED QUESTIONS
(1) The joint, nozzle and bottom of acoustic pipe are not tightly sealed, and mud or cement slurry leaks during construction, resulting in pipe plugging.
(2) During the installation and pouring of the acoustic pipe, the joint of the acoustic pipe is dislocated, deformed or the pipe wall is deformed due to the distortion or collision of steel bars. The main reason for this situation is the choice of thin-walled sound tube.
(3) In limestone area, it is difficult to drill holes. When the reinforcing cage is difficult to sink, unconventional means are used to deform and block the sound tube.
(4) When the pile head breaks, workers accidentally fall into small pieces of concrete, resulting in pipe plugging.
solution
The deformation and blockage of the acoustic wave detection tube bring great difficulties to the detection work, even impossible to detect. Therefore, effective measures should be taken to ensure the smooth progress of ultrasonic detection when the acoustic detection tube is found blocked after foundation pile pouring and before detection. Generally, there are three ways to make the pipe pass: poke the sound pipe with thick and long steel bars; Rinse pigging with high-pressure water; Sweep the hole with a drill with a small bit.
When the pipe blockage is serious, the following treatment principles must be followed: (1) When the first pile of the bridge is used, a coring test must be carried out; When the bridge is not the first pile, the construction unit shall declare the change of detection method, and adopt low-strain reflected wave method or high-strain dynamic detection method, which shall be implemented after being signed by the supervisor, the owner's representative and the person in charge of quality supervision; If a bridge is blocked many times, it is necessary to check the core in time.
Why can the length of the color-changing layer indicate the concentration of the target gas?
First of all, the sound tube manufacturer has testing reagents in the room (that is, the explanation of the above question: why the sound tube manufacturer changes color). Let's take the manufacturer of oxygen sound tube as an example. The sound tube factory is tightly filled with testing reagents, and the air is sucked into the sound tube factory by the gas collector during testing. Oxygen molecules in the air react with the detection reagent, which changes the reagent from black to white.
As time goes on, oxygen molecules enter the gap of the detector and contact with the detector, which deepens the manufacturer of the sound tube. This process continues to advance, layer by layer, until no oxygen enters and the color change stops.
Importantly, different concentrations mean different levels of oxygen in the air. When the amount of oxygen is large (high concentration), oxygen molecules will travel far (long whitening area). But when only a little oxygen is needed (low concentration), it will quickly pass through the reagent and react with it, so the whitening area is very short.
Therefore, the length of the color-changing layer of the sound tube manufacturer is directly proportional to the gas concentration, and the concentration of the target gas in the air can be detected by observing the color-changing length.
The detection reagent is filled in the sound tube manufacturers, for example, the white part in the carbon dioxide sound tube manufacturer and the black part in the oxygen sound tube manufacturer. When the gas to be detected comes into contact with the reagent. There will be chemical reactions and color changes. That is to say, once the detected gas passes through the sound tube manufacturer, the color change indicates the existence and concentration of the gas. It can be further explained:
The real reason for discoloration is that the detection reagent of the sound tube manufacturer reacts chemically when it comes into contact with gas, thus generating another different substance.
For example, when the white reagent in the carbon dioxide sound tube factory comes into contact with carbon dioxide gas, it will suddenly change and produce another purple substance. When the black reagent in the manufacturer of oxygen sound tube comes into contact with oxygen, another kind of white material is generated due to mutation.
Of course, there will be some manufacturers of gas-acoustic tubes that are different from the above, and there are also some differences in the process of change.
Specifications and models
Specification and model of clamp pressure sound tube:
50 * 0.8-2.0mm
54 * 0.8-2.0mm
57 * 0.8-2.0mm
Push-in/Screw-in/Clamping/Flanged Sound Tube Specifications:
50 *1.0-3.5mm
54 *1.0-3.5mm
57 *1.0-3.5mm
Specification and model of casing welding sound tube:
50 *1.5-3.5mm
54 *1.5-3.5mm
57 *1.5-3.5mm
Tel: 13673 178430