How to calculate the pull-out force of anchor rod
according to the calibration value on the calibration certificate of anchor tension meter or Jack, the oil pressure (MPA) is converted into pressure (KN) by interpolation method, and different instruments are used
bus line: fast line 5 → No.7, the whole journey is about 16.4km
1. Walk about 100m from Wuxi station to railway station (East)
2. Take fast line 5, pass 14 stations, and reach the East Station of Citizen Center
3. Walk about 900m to jiaheqiao station
4. Take No.7, pass 1 station, and reach Zhenze Road (Gonghu Avenue) station
5, and walk about 390m, Arrive at Wuxi Taihu International Expo
Calculation of bolt section area
As≥(ro*Na)/( ζ 2 * FY) where
as -- cross section area of anchor bar or prestressed steel strand
ro -- coefficient of working conditions for tensile strength of anchor bar, 0.69 for permanent anchor bar and 0.92 for temporary anchor bar
Na -- design value of axial tension of anchor rod (KN)
ζ 2 -- importance coefficient of slope engineering
FY -- design value of tensile strength of anchor bar or prestressed steel strand (kPa)
as a tension member deep into the stratum, one end of the anchor is connected with the engineering structure, and the other end is deep into the stratum. The whole anchor is divided into free section and anchorage section. The free section refers to the area where the tension at the anchor head is transmitted to the anchor solid, and its function is to impose prestress on the anchor
The function of the area where the cement paste binds the prestressed reinforcement to the soil layer is to increase the bonding friction between the anchor and the soil layer, increase the bearing effect of the anchor, and transfer the tension of the free section to the depth of the soil From the mechanical point of view, it mainly improves the cohesion c and internal friction angle of surrounding rock mass φ In essence, the bolt is located in the rock and soil body, and forms a new complex with the rock and soil body. The bolt in the complex is the key to solve the problem of low tensile capacity of surrounding rock mass. So the bearing capacity of rock and soil is greatly strengthenedbolt is the most basic component of roadway support in contemporary underground mining. It binds the surrounding rock of roadway together to support itself. Bolt is not only used in mines, but also in engineering technology, which is used for active reinforcement of slopes, tunnels and dams
drill in advance, screw the spin bolt into the drill hole, and then use the hollow grouting of the rod body after it is installed in place. A part of the slurry fills the space of the spin wire along the spin wire, and a part of the slurry penetrates into the rock to reinforce the rock stratum, so that the rock mass is anchored by the spin body and the rock mass is reinforced and grouted at the same time
The ultimate tensile force of the bolt should be twice of the design value, which is the requirement of the evaluation
as a tension member deep into the stratum, one end of the anchor is connected with the engineering structure, and the other end is deep into the stratum. The whole anchor is divided into free section and anchorage section. The free section refers to the area where the tension at the anchor head is transmitted to the anchor solid, and its function is to impose prestress on the anchor
the three-dimensional part of the new type of bolt is a high-strength steel pipe with longitudinal slit. When it is installed in a hole with a diameter slightly smaller than the diameter of the pipe, it can immediately apply radial pressure on the hole wall and the friction force to prevent the sliding of the surrounding rock in the full range, plus the supporting force of the anchor tray, so that the surrounding rock is in a three-dimensional stress state
extended data:
as a tension member deep into the stratum, one end of the bolt is connected with the engineering structure, and the other end is deep into the stratum. The whole bolt is divided into free section and anchorage section. The free section refers to the area where the tensile force at the bolt head is transmitted to the anchorage body, and its function is to pre stress the bolt
The function of the area where the cement paste binds the prestressed reinforcement to the soil layer is to increase the bonding friction between the anchor and the soil layer, increase the bearing effect of the anchor, and transfer the tension of the free section to the depth of the soilthe application of spin bolt has been fundamentally changed by using the hollow continuous small spiral wire structure instead of the large anchor leaf structure of traditional screw bolt and adopting different construction techniques. Thus, an all-round system of a series of functions is derived
the second test adopts graded loading, and the load grading shall not be less than 8. The maximum load of the test shall not be less than 2 times of the design load of the bolt
Article 3 after each level of load is applied, the displacement shall be measured immediately. After each interval of 5 minutes. When the pull-out value of the bolt measured for four times is less than 0.01mm, it is considered that the displacement under this level of load has reached a stable state, and the next level of pull-out load can be applied.
1. At least one group (3 bolts) shall be randomly sampled for each 300 bolts installed, and another group of drawing force tests shall be concted when the design or material changes
2. The average value of anchor force or pull-out force of the same group should be greater than or equal to the design value
3. The anchoring force or pulling force of a single bolt in the same group shall not be less than 90% of the design value
it is stipulated in the drawing force test of bolt in highway tunnel that the commonly used equipment for bolt drawing test is hollow jack, manual oil pump, oil pressure gauge and dial indicator< According to the purpose of the test, bolt holes are drilled in the designated part of the tunnel surrounding rock
2. Install the bolt to be tested according to the normal installation process
3. Determine the drawing time according to the type of anchor and the purpose of the test
4. Add a base plate at the end of the anchor rod, put on a hollow jack, fix the outer end of the anchor rod and the inner cylinder of the jack together, and install displacement measuring equipment and instruments
5. Pressurize by manual oil pump, read the oil pressure from the oil pressure gauge, and convert the pulling force of anchor rod according to the piston area
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According to the design requirements, if there are no design requirements, the ultimate tensile force of the bolt body (reinforcement) is used for destructive testing. For the full-length adhesive bolt, that is, the full-length grouting, the cohesive force is far greater than the rod body, that is, the rod body breaking is the ultimate tensile pull-out force
When one of the following conditions occurs, the pull-up test can be terminated:1
The newly added pull-up force could not be applied or could not keep stable after being applied3. The reinforcement of the bolt has been pulled out, or the reinforcement of the bolt has been pulled out
extended data:
when the range of the test bolt participating in the statistics does not exceed 30% of the average value, the average value can be taken as the ultimate bearing capacity of the bolt. When the range exceeds 30% of the average value, the test quantity should be increased and the reasons for the large deviation should be analyzed to determine the ultimate bearing capacity in combination with the engineering situation
The characteristic value of pullout bearing capacity RT is divided by safety factor 2.when drilling, the rock core should be processed into standard specimens, and the uniaxial compression test of rock should be carried out under the condition of natural humidity. The number of samples for each test bolt should not be less than 3
after the end of the test, it is necessary to make a detailed description and take photos of the failure of the anchor test site