Double-loop secondary tensioning jack and use method thereof
Technical Field
The invention relates to a double-loop secondary tensioning jack and a use method thereof, in particular to a double-loop secondary tensioning jack and a use method thereof, which are suitable for underground coal mines.
Background
In the current production and construction process of the first-line tunnel tunneling of the coal mine, the problem of lock standard and the problem of matching of the lock and the expansion pump jack are seriously ignored. The reading of the tension pump is mistakenly used as the prestress provided for the top plate, the actual loss is 50% -70%, the prestress is required to be 130KN by the anchor cable with the diameter of 17.8X6200 mm, the actual applied pressure is only 40-65KN, the torque value of the common threaded steel anchor rod is 300N.m, the actual construction prestress is 60-70KN, so that the pressure of the partial anchor cable for the top plate construction is not actually larger than the prestress provided by 1 anchor rod, and serious potential safety hazards of the top plate exist, but are always ignored by people.
Under the tensioning state of the anchor cable, the height of the lock core exposed out of the lock ring is a, and the height difference between the jack anchor pipe and the jacking device is b.
When a=b, the effect is most ideal, but in the first line production practice, the occurrence probability of such a case is almost 0%.
When a > b, means that when the lock ring does not reach the designated strength yet, the lock core is locked in advance, the truly effective contact surface between the jack and the lock should be the lock core and the top anchor pipe, the prestress is only transmitted to the exposed part of the lock and below the anchor cable, and can not be effectively transmitted to the rod body of the anchor cable steel strand, and the most common occurrence probability of the situation is about 95%.
When a < b, the lock core of the lockset is not matched with the lock ring in size, when the lock ring and the lock core are under larger pressure, the lock core is not completely locked, after the anchor is removed, the lock ring and the lock core move down asynchronously, the lock core is influenced by friction resistance of an anchor rope, the stroke is smaller than the downward moving distance of the lock ring, and the prestress loss is the largest under the condition.
At present, the single-loop primary expansion jack is on the market, the top anchor pipe and the jacking device are integrally and mechanically connected, the middle cylinder piston pushes the top anchor spring during expansion, the top anchor spring is pushed to synchronously move upwards after being pressed, the primary expansion jack can only be realized, and in the expansion process, the prestress loss is overlarge due to the matching of the lockset quality and lockset with the jack described in the background technology. The effective prestressing force is much smaller than the design prestressing force.
Disclosure of Invention
Technical problems: the invention aims to overcome the defects in the prior art, and provides a double-loop secondary expansion jack which has a simple structure and is convenient to use, the multiple expansion of a jacking pipe and a jacking device can be realized, and the serious problem of prestress loss caused by the problems of lock quality and matching of a lock and the jack can be effectively reduced, and a use method thereof.
The technical scheme is as follows: in order to achieve the purpose, the double-loop secondary tensioning jack comprises an upper piston jack and a lower piston jack, and a fastening tensioning device is arranged between the upper piston jack and the lower piston jack;
the upper piston jack comprises a columnar jacking device, a jacking pipe is axially arranged in the jacking device, a cavity is formed in the jacking device, the jacking pipe is surrounded by the jacking pipe, a jacking pipe piston is arranged in the cavity by taking the jacking pipe as a piston shaft, an anchor unloading ring is arranged at the bottom of the jacking device to seal the cavity of the jacking device and fix the jacking pipe, pipelines which are connected with the internal cavity are respectively arranged at the upper part and the lower part of the side wall of the jacking device, and the cavity is divided into a jacking pipe expansion-pulling liquid inlet cavity below and a jacking pipe withdrawal liquid return cavity above by the jacking pipe piston;
the lower piston jack comprises a piston cylinder outer cylinder, a piston cylinder inner cylinder is axially arranged in the piston cylinder outer cylinder, an inner cylinder piston is arranged in the middle of the piston cylinder inner cylinder, a middle cylinder piston is arranged at the upper part of the piston cylinder inner cylinder, a cavity of the piston cylinder outer cylinder is divided into an upper ejector anchor withdrawal oil return cavity and a lower ejector expanding and pulling liquid inlet cavity by the inner cylinder piston, two pipelines are respectively arranged on the upper side wall and the lower side wall of the piston cylinder outer cylinder and are respectively communicated with the ejector anchor withdrawal oil return cavity and the ejector expanding and pulling liquid inlet cavity, the bottom of the middle cylinder piston is arranged in the ejector anchor withdrawal oil return cavity, and the top of the middle cylinder piston extends out of the middle cylinder piston to be fixedly connected with the bottom of the ejector;
the anchor ejection pipe anchor withdrawal liquid return cavity is communicated with the ejector anchor withdrawal oil return cavity through a double-section telescopic sleeve, and the anchor ejection pipe expansion liquid inlet cavity is communicated with the ejector anchor expansion liquid inlet cavity through a double-section telescopic sleeve;
a space for fixing the anchor cable lockset is reserved between the top of the middle cylinder piston and the anchor unloading ring at the bottom of the jacking device.
The ejector is characterized in that a 0-shaped sealing ring is arranged between the ejector and the ejector, and between the ejector and the ejector, a 0-shaped sealing ring is arranged between the middle cylinder piston and the outer cylinder of the piston cylinder, and the 0-shaped sealing ring is respectively arranged between the middle cylinder piston and the outer cylinder of the piston cylinder and between the middle cylinder piston and the inner cylinder of the piston cylinder.
The inner cylinder of the piston cylinder penetrates through the concentric circular through hole at the bottom of the outer cylinder of the piston cylinder and is connected with the outer cylinder of the piston cylinder through a nut at the tail part, a retaining screw is arranged on the nut, and a rear cover is arranged at the bottom of the outer cylinder of the piston cylinder to seal and fix the bottom of the inner cylinder of the piston cylinder.
The two-position four-way valve is provided with a quick connector.
The working method of the double-loop secondary tensioning jack comprises the following steps:
a. the double-loop secondary expansion jack firstly withdraws the middle cylinder piston of the expansion jack to the lowest position, and inserts the steel stranded wire at the tail end of the anchor cable into the top anchor pipe of the top press device to lift the expansion pump jack so as to avoid the falling of the expansion pump jack;
b. carrying out primary jacking device expansion: hydraulic oil is injected into the expanding-pulling liquid inlet cavity of the jack pump head jack-up anchor cable lock ring, the inner cylinder of the piston cylinder is pushed to move upwards, the middle cylinder piston is driven to extend upwards, the anchor pushing pipe is separated from a tool anchor fixed in the inner cylinder of the piston cylinder in the extending process of the middle cylinder piston, and the tool anchor locks the steel strand of the anchor cable under the pushing of elasticity, so that the steel strand is continuously stretched when the oil cylinder is ejected out, the jack pump head jack-up anchor cable lock ring is tightly pushed, and after the appointed strength is reached, the jack-up anchor cable lock ring is hydraulically locked, and one expanding-pulling is completed;
c. carrying out secondary jacking device expansion: hydraulic oil is injected into the top anchor pipe expansion-pulling liquid inlet cavity to push the top anchor pipe piston to enable the top anchor pipe to extend out, the anchor rope lock cylinder is tightly propped, when the top anchor pipe reaches the specified pressure on the top plate, expansion-pulling is stopped, the top anchor pipe expansion-pulling liquid inlet cavity is hydraulically locked, secondary expansion-pulling is completed, effective prestress of the lock ring on the tray is improved through secondary expansion-pulling, the locking firmness degree of the lock cylinder is enhanced, the top plate supporting quality is further improved, and the safety of the top plate for one-line construction is ensured;
d. after the secondary expansion is finished, controlling the anchor pushing pipe to withdraw the anchor, controlling a two-position four-way valve connected with an anchor pushing pipe expansion liquid inlet cavity to release the hydraulic locking of the anchor pushing pipe expansion liquid inlet cavity, controlling the anchor pushing pipe withdrawal liquid return cavity to be opened, injecting hydraulic oil into the anchor pushing pipe withdrawal liquid return cavity, and enabling an anchor pushing pipe piston to move downwards to complete anchor pushing pipe withdrawal;
e. the ejector is withdrawn from the anchor: after the top anchor pipe is retracted, the two-position four-way valve connected with the top anchor pipe anchor withdrawal and return liquid cavity is controlled to inject hydraulic oil into the top press anchor withdrawal and return liquid cavity, so that the piston of the middle cylinder moves downwards and returns to the lowest position in the inner cylinder of the piston cylinder, and the whole anchor withdrawal process of the top press is realized.
The beneficial effects are that:
(1) The double-loop secondary tensioning jack can realize the fractional tensioning of the top anchor pipe and the top presser, and effectively reduces the problem of serious prestress loss caused by the matching problem of the lockset quality and the lockset and the jack.
(2) The hydraulic oil enters the jacking device expansion liquid inlet cavity to realize primary expansion and hydraulic locking, hydraulic pressure is injected into the jacking pipe expansion liquid inlet cavity to realize secondary expansion and hydraulic locking, after the expansion is finished, the hydraulic oil is released to enter the jacking pipe withdrawal liquid return cavity to realize jacking pipe withdrawal, the hydraulic oil is controlled to enter the jacking device withdrawal liquid return cavity to realize jacking device withdrawal, and therefore the whole expansion and pulling process is completed, and the expansion liquid inlet hydraulic loop and the withdrawal liquid return hydraulic loop are respectively arranged at two sides of a jack to facilitate lifting;
(3) The ejector anchor withdrawing and returning liquid cavity, the ejector expanding and pulling liquid inlet cavity, the ejector anchor pipe expanding and pulling liquid inlet cavity and the ejector anchor pipe anchor withdrawing and returning liquid cavity are longitudinally arranged, so that the structure is simple, and the integration of a double-loop hydraulic system is realized;
the double-loop secondary tensioning jack releases mechanical connection between the top anchor pipe and the top presser, and is completely separated, so that primary tensioning of the top presser and the lock ring and secondary tensioning of the top anchor pipe and the lock core are realized. The design defect of the anchor cable lock catch and the lock core is overcome, the problems that the lock is not matched with the jack and the like are solved, the effective prestress of the lock catch to the tray is improved through secondary tensioning, the locking firmness of the lock core is enhanced, the roof supporting quality is further improved, and the roof safety of one-line construction is ensured.
Drawings
Fig. 1 is a structural diagram of a double-loop secondary tensioning jack of the present invention.
Fig. 2 is a block diagram of a double loop secondary tensioning jack and a matched anchor cable of the present invention.
FIG. 3 is a diagram of an anchor cable lockset mechanism matched with a double-loop secondary tensioning jack.
In the figure: the device comprises a 1-top anchor pipe, a 2-top presser, a 3-anchor unloading ring, a 4-anchor cup, a 5-tool anchor, a 6-reset spring and a 7-double-section telescopic sleeve; the hydraulic pressure control device comprises an 8-two-position four-way valve, a 9-middle cylinder piston, a 10-ejector anchor withdrawing and returning oil cavity, an 11-piston cylinder outer cylinder, a 12-piston cylinder inner cylinder, a 13-ejector anchor withdrawing and returning oil cavity, a 14-quick connector, a 15-sealing plug, a 16-retaining screw, a 17-nut, a 18-rear cover, a 19-0-shaped sealing ring, a 20-ejector anchor pipe expanding and returning oil cavity and a 21-ejector anchor pipe anchor withdrawing and returning oil cavity.
Detailed Description
An embodiment of the invention is further described below with reference to the accompanying drawings:
as shown in fig. 1, 2 and 3, the double-loop secondary tensioning jack comprises an upper piston jack and a lower piston jack, and a fastening tensioning device is arranged between the upper piston jack and the lower piston jack;
the upper piston jack comprises a columnar jacking device 2, a jacking pipe 1 is axially arranged in the jacking device 2, a cavity is formed in the jacking device 2 around the jacking pipe 1, a jacking pipe piston is arranged in the cavity by taking the jacking pipe 1 as a piston shaft, an anchor unloading ring 3 is arranged at the bottom of the jacking device 2 to seal the cavity of the jacking device 2 and fix the jacking pipe 1, pipelines which are connected with the internal cavity are respectively arranged on the upper side wall and the lower side wall of the jacking device 2, wherein the jacking pipe piston divides the cavity into a jacking pipe expansion liquid inlet cavity 20 below and a jacking pipe withdrawal liquid return cavity 21 above;
the lower piston jack comprises a piston cylinder outer cylinder 11, a piston cylinder inner cylinder 12 is axially arranged in the piston cylinder outer cylinder 11, an inner cylinder piston is arranged in the middle of the piston cylinder inner cylinder 12, a middle cylinder piston 9 is arranged at the upper part of the piston cylinder inner cylinder 12, a cavity of the piston cylinder outer cylinder 11 is divided into an upper ejector anchor withdrawal oil cavity 10 and a lower ejector tensioning liquid inlet cavity 13 by the inner cylinder piston, two pipelines are respectively arranged on the upper side wall and the lower side wall of the piston cylinder outer cylinder 11, and are respectively communicated with the ejector anchor withdrawal oil cavity 10 and the ejector tensioning liquid inlet cavity 13, wherein the bottom of the middle cylinder piston 9 is arranged in the ejector anchor withdrawal oil cavity 10, and the top of the middle cylinder piston 9 extends out of the middle cylinder piston 9 to be fixedly connected with the bottom of the ejector 2; the ejector 2 is characterized in that a 0-shaped sealing ring is arranged between the ejector 2 and the ejector 2, and between the middle cylinder piston 9 and the outer cylinder 11, and between the middle cylinder piston 9 and the inner cylinder 12, 0-shaped sealing rings are respectively arranged. The piston cylinder inner cylinder 12 passes through a concentric through hole at the bottom of the piston cylinder outer cylinder 11 and is connected with the piston cylinder outer cylinder 11 through a nut 17 at the tail part, a stop screw 16 is arranged on the nut 17, and a rear cover 18 is arranged at the bottom of the piston cylinder outer cylinder 11 to seal and fix the bottom of the piston cylinder inner cylinder 12.
The anchor ejection pipe anchor withdrawal liquid return cavity 21 is communicated with the ejector anchor withdrawal oil return cavity 10 through the double-section telescopic sleeve 7, and the anchor ejection pipe expansion liquid inlet cavity 20 is communicated with the ejector anchor expansion liquid inlet cavity 13 through the double-section telescopic sleeve 7;
a space for fixing the anchor cable lock is reserved between the top of the middle cylinder piston 9 and the anchor unloading ring 3 at the bottom of the jacking device 2.
The two-position four-way valve 8 is arranged between the anchor pipe withdrawal liquid return cavity 21 and the roof pressure ware withdrawal oil return cavity 10, and the two-position four-way valve 8 is provided with a quick connector 14 between the anchor pipe expansion liquid inlet cavity 20 and the roof pressure ware expansion liquid inlet cavity 13.
The working method of the double-loop secondary tensioning jack comprises the following specific steps:
a. the double-loop secondary expansion jack firstly withdraws the middle cylinder piston 9 of the expansion jack to the lowest position, and inserts the steel stranded wire at the tail end of the anchor cable into the top anchor pipe 1 of the jack 2 to lift the expansion pump jack, so as to avoid the falling of the expansion pump jack;
b. carrying out primary jacking device expansion: hydraulic oil is injected into the expansion-pulling liquid inlet cavity 13 of the jack pump head jack 2 to jack the lock ring of the anchor cable, the piston cylinder inner cylinder 12 is pushed to move upwards, the middle cylinder piston 9 is driven to extend upwards, the anchor pushing pipe 1 is separated from the tool anchor 5 fixed on the piston cylinder inner cylinder 12 in the extending process of the middle cylinder piston 9, the tool anchor 5 locks the steel strand of the anchor cable under the pushing of elasticity, the steel strand is continuously stretched when the oil cylinder is ejected, the jack pump head jack 2 is pushed against the lock ring of the anchor cable lock, and after the appointed strength is reached, the jack pump head jack expansion-pulling liquid inlet cavity 13 is hydraulically locked, and one expansion-pulling is completed;
c. carrying out secondary jacking device expansion: hydraulic oil is injected into the top anchor pipe expansion drawing liquid inlet cavity 20 to push the top anchor pipe piston to enable the top anchor pipe 1 to extend, the anchor rope lock cylinder is tightly propped, when the top anchor pipe 1 reaches the specified pressure on the top plate, expansion drawing is stopped, the top anchor pipe expansion drawing liquid inlet cavity 20 is hydraulically locked, secondary expansion drawing is completed, effective prestress of the lock ring on the tray is improved through secondary expansion drawing, the locking firmness of the lock cylinder is enhanced, the top plate supporting quality is further improved, and the top plate safety of one-line construction is ensured;
d. after the secondary expansion is finished, controlling the anchor pushing pipe 1 to withdraw the anchor, controlling the two-position four-way valve 8 connected with the anchor pushing pipe expansion liquid inlet cavity 20 to release the hydraulic lock of the anchor pushing pipe expansion liquid inlet cavity 20, controlling the anchor pushing pipe withdrawal liquid return cavity 21 to be opened, injecting hydraulic oil into the anchor pushing pipe withdrawal liquid return cavity 21, and enabling the anchor pushing pipe piston to move downwards to complete anchor pushing pipe withdrawal;
e. the ejector 2 is anchored: after the top anchor pipe 1 is retracted, the two-position four-way valve 8 connected with the top anchor pipe anchor withdrawing and returning liquid cavity 21 is controlled to inject hydraulic oil into the top press anchor withdrawing and returning liquid cavity 10, so that the middle cylinder piston 9 moves downwards and returns to the lowest position in the piston cylinder inner cylinder 12, and the whole anchor withdrawing step of the top press 2 is realized.