A anchor spray support construction equipment
a There are mainly concrete jets, jet robots and jet combined units, as well as auxiliary tools such as concrete mixers and feeders.
Recently, domestic and international concrete injection machinery has developed rapidly. It has developed from dry spray to semi-wet and wet spray. The main models of dry jet have upper and lower double tank, swivel, drum, spiral and semi-wet spray. The machine mainly has two-tank side-by-side type, upper and lower tank type and upper and lower barrel type. The wet type jet machine mainly has single tank type, double tank type, rotary type and double tank type. Models and technical performance of domestic concrete jets, jet robots and jet combined units.
b Bolt support construction machine The construction machine is mainly the bolt installation machine. In addition, there is an auxiliary machine for bolting holes.
B Shotcrete support construction technology
a Selection of process parameters ( 1 ) Working pressure. Refers to the air pressure in the sprayer working tank during normal operation. Proper control of air pressure reduces rebound and dust and ensures concrete quality. The value is related to the conveying distance, the elevation, the bending degree of the conveying pipe, the moisture content of the dry mixture and the amount of dry material passing through the unit time. Use Yejian -65 jet type, cement, sand, gravel with the ratio of 1: 2.5: 2 by the spray nozzle from the surface of the delivery conduit length 1m 20m  When the working pressure is 0.11~0.13MPa, it is suitable. The working pressure and no-load air pressure of the jet increase with the length of the conveying pipe, and basically meet the requirements; flush the rock wall with pressurized water, and clean the loose stone, the length of one cleaning can be determined according to the progress of a possible injection. , remove the unused air pipes, etc.; bury the piles for checking the thickness of the spray; check the gas and water pipes and the lighting and dustproof measures for the jetting operations; and wear the protective equipment for the operators.
( 2 ) Jetting operation. This includes the operation of the jet and the spray head, of which the correct operation of the spray head is particularly important. The operation of the jet machine should be strictly controlled according to the operation steps. It is the key to adjust the air pressure; the length of the feed pipe is 20m , and the longest is not more than 30m .
( 3 ) Dust-proof measures. According to practical experience, the main dust prevention measures are: Increase the moisture content of sand and gravel, generally 5~8% is suitable, and strictly control the working pressure between 0.11~0.13MPa . According to the measurement, when the pressure is increased to 0.15~0.16MPa , dust a concentration of from 8.25ms / m3 increased 11.68mg / m3; rope feed tube length increases, the Meishan iron ore 25cm to 50cm, good results; all the way from the nozzle inlet to two water; proper operation and enhance ventilation.
c handling of several problems in construction
( 1 ) High rebound rate. The rebound rate of the wall and the arch is required to be controlled below 15% and 25%, respectively . The main measures are: The process and operation are strictly in accordance with the design requirements; the selection of materials should pay attention to the variety and amount of cement, the size and gradation of sand and gravel particles, the water-cement ratio, the variety and dosage of accelerator.
( 2 ) Partial exfoliation. There are three main cases of local spalling of thin sprayed layer: weathering and desorption expansion of surrounding rock; poor bonding between spray and rock; corrosion of acidic medium.
In this regard, comprehensive and targeted measures should be taken: the thickness of the jet should be no less than 50mm to clean the rock and improve the cohesive force. For the surrounding rock that disintegrates or expands with water, the joint support of the spray anchor net should generally be adopted to isolate the influence of water. It is necessary to close the rock face early, and the working face should dig trenches to drain water in time; for areas with sulfate medium erosion, anti-sulphate cement should be used.
(3 ) The main preventive measures for losing the foot (that is, the wall root is exposed to the rock gang and the upper spray layer is suspended) are: according to the design section specification, once to the bottom level, when burrowing in the expansive surrounding rock or loose surrounding rock and there is water inrush, The root of the wall should be dug to 200mm below the bottom of the floor. Â Left and right, clean the wall root and spray it first. The wall should be supported by anchor-spraying spray anchor net. After the roadway anchor spray support, the connection between the ditch and the ditch and the wall root should be done as soon as possible; When the drum phenomenon occurs, the concrete reverse arch should also be poured.
( 4 ) The causes of the cracks are: the concrete mix ratio is not good; the thickness of the spray layer is uneven; the cement type is improperly selected; the maintenance work is poor. In addition, external forces (such as blasting) can also cause cracks. To identify the cause, take comprehensive measures in a targeted manner.
( 5 ) Leakage water and its treatment methods are as follows:
When a large area leaks water, first find out the water source, then shoot the concrete or mortar with the quick-setting agent at a high speed to the water source point, so that the crack will quickly condense. When there is pressure leaking, first estimate the water line. The direction of the hole, after drilling , the water is led out ; when the large crack leaks, first drill a 1.2~1.3m deep hole on the intact rock on the side of the crack , then install the water pipe at the hole to make the water flow smoothly. At the same time, the stone is used in the large cracks, and the surface is sprayed with 300mm thick concrete to block the water.
C bolt support construction technology
a Technical work to be done when using bolt support ( 1 ) Requires more accurate geological data for the support area, such as lithology, occurrence, robustness, and fracture groups of the rock formation, in order to make a realistic design. ;
( 2 ) Strict quality inspections are required to ensure the best possible support. In addition to the bolt specifications material, installation spacing, hole depth and backing plate quality, the anchoring force test must also be determined;
( 3 ) For mortar, resin and cement anchors, the strength and filling density test of the filling is to be done;
( 4 ) Conduct a series of observations and monitoring work.
b Installation of anchors There are many types of anchors, except for the holes that must be drilled. The methods of installation are different.
a There are mainly concrete jets, jet robots and jet combined units, as well as auxiliary tools such as concrete mixers and feeders.
Recently, domestic and international concrete injection machinery has developed rapidly. It has developed from dry spray to semi-wet and wet spray. The main models of dry jet have upper and lower double tank, swivel, drum, spiral and semi-wet spray. The machine mainly has two-tank side-by-side type, upper and lower tank type and upper and lower barrel type. The wet type jet machine mainly has single tank type, double tank type, rotary type and double tank type. Models and technical performance of domestic concrete jets, jet robots and jet combined units.
b Bolt support construction machine The construction machine is mainly the bolt installation machine. In addition, there is an auxiliary machine for bolting holes.
B Shotcrete support construction technology
a Selection of process parameters ( 1 ) Working pressure. Refers to the air pressure in the sprayer working tank during normal operation. Proper control of air pressure reduces rebound and dust and ensures concrete quality. The value is related to the conveying distance, the elevation, the bending degree of the conveying pipe, the moisture content of the dry mixture and the amount of dry material passing through the unit time. Use Yejian -65 jet type, cement, sand, gravel with the ratio of 1: 2.5: 2 by the spray nozzle from the surface of the delivery conduit length 1m 20m  When the working pressure is 0.11~0.13MPa, it is suitable. The working pressure and no-load air pressure of the jet increase with the length of the conveying pipe, and basically meet the requirements; flush the rock wall with pressurized water, and clean the loose stone, the length of one cleaning can be determined according to the progress of a possible injection. , remove the unused air pipes, etc.; bury the piles for checking the thickness of the spray; check the gas and water pipes and the lighting and dustproof measures for the jetting operations; and wear the protective equipment for the operators.
( 2 ) Jetting operation. This includes the operation of the jet and the spray head, of which the correct operation of the spray head is particularly important. The operation of the jet machine should be strictly controlled according to the operation steps. It is the key to adjust the air pressure; the length of the feed pipe is 20m , and the longest is not more than 30m .
( 3 ) Dust-proof measures. According to practical experience, the main dust prevention measures are: Increase the moisture content of sand and gravel, generally 5~8% is suitable, and strictly control the working pressure between 0.11~0.13MPa . According to the measurement, when the pressure is increased to 0.15~0.16MPa , dust a concentration of from 8.25ms / m3 increased 11.68mg / m3; rope feed tube length increases, the Meishan iron ore 25cm to 50cm, good results; all the way from the nozzle inlet to two water; proper operation and enhance ventilation.
c handling of several problems in construction
( 1 ) High rebound rate. The rebound rate of the wall and the arch is required to be controlled below 15% and 25%, respectively . The main measures are: The process and operation are strictly in accordance with the design requirements; the selection of materials should pay attention to the variety and amount of cement, the size and gradation of sand and gravel particles, the water-cement ratio, the variety and dosage of accelerator.
( 2 ) Partial exfoliation. There are three main cases of local spalling of thin sprayed layer: weathering and desorption expansion of surrounding rock; poor bonding between spray and rock; corrosion of acidic medium.
In this regard, comprehensive and targeted measures should be taken: the thickness of the jet should be no less than 50mm to clean the rock and improve the cohesive force. For the surrounding rock that disintegrates or expands with water, the joint support of the spray anchor net should generally be adopted to isolate the influence of water. It is necessary to close the rock face early, and the working face should dig trenches to drain water in time; for areas with sulfate medium erosion, anti-sulphate cement should be used.
(3 ) The main preventive measures for losing the foot (that is, the wall root is exposed to the rock gang and the upper spray layer is suspended) are: according to the design section specification, once to the bottom level, when burrowing in the expansive surrounding rock or loose surrounding rock and there is water inrush, The root of the wall should be dug to 200mm below the bottom of the floor. Â Left and right, clean the wall root and spray it first. The wall should be supported by anchor-spraying spray anchor net. After the roadway anchor spray support, the connection between the ditch and the ditch and the wall root should be done as soon as possible; When the drum phenomenon occurs, the concrete reverse arch should also be poured.
( 4 ) The causes of the cracks are: the concrete mix ratio is not good; the thickness of the spray layer is uneven; the cement type is improperly selected; the maintenance work is poor. In addition, external forces (such as blasting) can also cause cracks. To identify the cause, take comprehensive measures in a targeted manner.
( 5 ) Leakage water and its treatment methods are as follows:
When a large area leaks water, first find out the water source, then shoot the concrete or mortar with the quick-setting agent at a high speed to the water source point, so that the crack will quickly condense. When there is pressure leaking, first estimate the water line. The direction of the hole, after drilling , the water is led out ; when the large crack leaks, first drill a 1.2~1.3m deep hole on the intact rock on the side of the crack , then install the water pipe at the hole to make the water flow smoothly. At the same time, the stone is used in the large cracks, and the surface is sprayed with 300mm thick concrete to block the water.
C bolt support construction technology
a Technical work to be done when using bolt support ( 1 ) Requires more accurate geological data for the support area, such as lithology, occurrence, robustness, and fracture groups of the rock formation, in order to make a realistic design. ;
( 2 ) Strict quality inspections are required to ensure the best possible support. In addition to the bolt specifications material, installation spacing, hole depth and backing plate quality, the anchoring force test must also be determined;
( 3 ) For mortar, resin and cement anchors, the strength and filling density test of the filling is to be done;
( 4 ) Conduct a series of observations and monitoring work.
b Installation of anchors There are many types of anchors, except for the holes that must be drilled. The methods of installation are different.
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