Digital in-situ press machine

　　Digital in-situ press machineDigital display masonry in-situ pressure machine, masonry wall in-situ axial pressure instrument, brick masonry compressive strength testing machine, 80 ton in-situ pressure testing machine, in-situ pressure instrument, brick masonry in-situ * instrument

1、 Product Usage:

SL-80T typeDigital in-situ press machineIt is a specialized equipment that uses a hydraulic system to conduct on-site testing of the compressive strength of masonry. Compared with indirectly calculating the compressive strength of masonry by testing the strength of bricks and mortar, it is more intuitive and provides reliable data for the reliability assessment, reinforcement, reconstruction, layer addition, and analysis of engineering accidents in buildings.

This product adopts a low-power high-precision digital pressure gauge produced by Aerospace Technology. It is a new generation product with small size and high integration in China, ensuring the accuracy of detection data. It complies with the national standard "Technical Standard for On site Inspection of Masonry Engineering" (GB/T50315-2011)

2、 Technical parameters:

3、 Structure and working principle:

The system is composed of a manual pump and a jack connected by a high-pressure oil pipe. When the return valve is closed, the manual pump starts to send oil to the kilogram, pushing the piston upwards. The digital display changes with the increasing pressure until the measured object is destroyed. After the work is completed, the return valve can be opened and the oil can flow back to the manual pump. Record the peak value of the pressure gauge and calculate the strength of the masonry according to the formula.

2. Structural composition

1. Manual oil pump 2, digital pressure gauge 3, high-pressure oil pipe 4, jack 5, pull rod (four pieces) 6, reaction plate 7, nut 8, masonry 9, sand cushion layer

4、 Installation and Debugging:

After unpacking, check and count the quantity of components according to the packing list to ensure they are complete, and wipe the components clean before installation.

Connect the three-way valve directly to the outlet of the manual pump, and use a high-pressure hose to connect the manual pump to the hydraulic cylinder through the three-way valve.

Close the oil pump valve, open the oil pump cap, and fill the manual pump oil tank with clean 46 # hydraulic oil.

Apply a certain load such as a counterweight to the hydraulic cylinder, open the exhaust screw, and use the hand pump to pressurize and release air until oil flows out, which is considered as air to be discharged. Then tighten the screw. If it cannot be completely discharged at once, repeat the process multiple times. After the air is completely discharged, close the oil pump valve and wait for use. The above steps need to be repeated every time the instrument is disassembled.

5. Experimental steps

5.1 When excavating horizontal grooves at testing points, the following regulations should be followed:

The testing point should be placed at a height of about one meter from the ground in the middle of the wall, and the walls on both sides should be constrained by at least 1.5 meters. There should not be more than one testing point on the same wall.

Drill two holes on the selected wall, with a size of 250X250X70mm. The size of the lower hole is 250X250X140mm, and the upper and lower holes B must be aligned. The vertical distance between the two holes is 24, which is 7 bricks high from the wall, and 37, which is 8 bricks high from the wall. When opening holes, attention should be paid not to loosen the masonry between the two holes and around them. The upper and lower surfaces of the holes should be flat brick surfaces

5.2 When placing an in-situ press between slot holes, the following regulations should be followed:

Place the reaction plate in the upper slot and the jack in the lower slot. Spread wet fine sand evenly on the lower surface of the upper slot and the top surface of the jack, with a thickness of no more than 10mm. Place four steel tie rods to align the two pressure plates, tighten the nuts and adjust their parallelism. The net distance error between the upper and lower nut keys of the four steel tie rods should not exceed 2mm. Before formal testing, a trial loading test should be conducted, and the trial loading value can be taken as 10% of the estimated failure load. Check the flexibility and reliability of the testing system, as well as whether the contact between the upper and lower pressure plates and the compression surface of the masonry is uniform and dense. After adding load and testing the system normally, unload and begin formal testing.

During formal testing, loading should be graded. Each level of load can be taken as 10% of the estimated failure load, and should be evenly applied within 1-1.5 minutes, followed by a static load of 2 minutes. Load up to 80% of the estimated failure load, and continue to load at the original loading rate until the masonry between the grooves is damaged. When the cracks in the masonry between the grooves rapidly expand and increase, and the number on the pressure gauge no longer increases, the masonry between the grooves reaches the J limit state.

During the testing process, if it is found that the upper and lower pressure plates and the bearing surface of the masonry are in good contact, resulting in local or eccentric compression of the masonry between the grooves, the test should be stopped. At this point, the testing device should be adjusted and retested. If adjustment is not possible, the measuring point should be replaced.

During the 5.5 test, it is necessary to carefully observe the occurrence and development of cracks in the masonry between the grooves, record the readings of the oil pressure gauge, the positions of the measuring points, and a schematic diagram of the changes in cracks with the load under step-by-step loading.

6. Data analysis

6.1 Calculate the initial cracking load and failure load of the masonry between grooves based on the readings of the digital pressure gauge indicating the initial cracking and failure of the masonry between grooves

The compressive strength of the masonry between grooves should be calculated according to the following formula.

fuij=Nuij/Aij

In the formula, fuij represents the compressive strength (MPa) of the masonry between the i-th and j-th test points in the groove

The compressive failure load value (KN) of the masonry between the i-th measuring area and j-th measuring point in Nuij

Aij -------- Compressive area of masonry between the i-th measuring area and j-th measuring point slot (mm2)

6.3 When converting the compressive strength of masonry between grooves into the compressive strength of standard masonry, it should be calculated according to the following formula:

In the formula, the converted value of the compressive strength of the standard masonry at the i-th measuring area and j-th measuring point is Mpa

--------Non dimensional strength conversion coefficient of in-situ axial compression method

------The working compressive stress (Mpa) of the upper wall of the measuring point can be calculated based on the actual load standard value of the wall

The average compressive strength of masonry in the 6.4 test area should be calculated according to the following formula:

In the formula, the average compressive strength of the masonry in the i-th test area (Mpa)

N1------- Number of measurement points in the measurement area

7. Precautions during the testing process:

7.1 When assembling the instrument, the two upper pressure plates should be aligned vertically, and their parallelism should be adjusted when tightening the nuts. Wet fine sand cushion or gypsum can be evenly laid between the contact surfaces with the masonry, with a thickness not exceeding 10mm. The net distance error between the upper and lower nuts of the four tension rods should not exceed 2mm

During the testing process, if the upper and lower pressure plates are in good contact with the masonry and experience eccentric compression, and the distance error between the upper and lower plates is greater than 5mm, the testing should be stopped and adjusted in a timely manner to prevent the piston from getting stuck with the cylinder body and causing damage to the oil cylinder.

During the testing process, the piston should move and extend. If the piston does not extend smoothly and there is a Dongguan phenomenon, it indicates that the air in the oil cylinder has not been completely discharged. The test should be paused, and the exhaust should be repeated. After the air is completely discharged, the test can be restarted.

During the testing process, the hydraulic system should not be disassembled. If disassembly is necessary, the return valve should be opened first, and disassembly should be carried out when there is no pressure in the system.

Due to the lack of automatic retraction function in the hydraulic cylinder, after the inspection is completed, please open the return valve and evenly tighten the nuts on the self balancing tension screw diagonally to restore the piston position.