A kind of active self adaptation constant-resistance lengthener of prestress anchorage cable
Technical field
The present invention relates to the rock mass safety support field of geotechnical engineering, more specifically relate to a kind of active self adaptation constant-resistance lengthener of prestress anchorage cable, it is applicable to adopts the prestressed anchor reinforcement rock mass in slope project or the underground construction.
Background technology
Restricted by China's complex engineering geological conditions, large-scale geotechnical engineering construction such as water power, traffic, resource, the energy, national defence, as western hydroelectric development, the south water to north, deep mining, oil/gas exploitation, the storage of the strategic energy, water power side slope, underground military project blindage engineering etc., all relate to this support technology that adopts the prestressed anchor reinforcement engineering rock mass.Yet engineering rock mass all can discharge because of ever-increasing in time distortion takes place for rock mass stress off-load effect and the secular distortion characteristic of rock mass own usually.; being installed in prestress anchorage cable on the engineering rock mass all can't work in coordination with the distortion of this Bolted Rock Masses usually adaptively and increase; this has just caused anchor cable steel strand load along with the time constantly increases, and then causes it to exceed the ultimate strength of anchor cable itself and anchor cable steel strand fractures takes place.As in underground construction, just bring out large deformation in China's two beach underground workshop construction process because of engineering rock mass abruptly brittle rupture, cause a plurality of anchor cable fractures; Mid-board between silk screen second cascade hydropower station underground power house and the transformer chamber also ruptures because of the rock mass continuous deformation makes anchor cable steel strand load go beyond the limit of intensity.In slope project, lax large deformation takes place in engineering rock mass under long-term natural force and artificial disturbance, has caused equally surpassing its ultimate strength value because of anchor cable can't adapt to its load of rock mass large deformation, and then anchor cable destruction occurred, jeopardizes slope project safety.
As a whole, the engineering rock mass large deformation basic reason that causes adapting to rock mass deformation at the anchor cable load is the elongation per unit length that the anchor cable steel strand are lower.According to China's " steel strand for prestressed concrete " national standards (GB/T5224-1995) regulation, the steel strand of prestress anchorage cable all are high strength low elongation steel.Because this high strength steel strand do not have tangible plastic strain section, thus when the engineering rock mass generation large deformation of its anchoring then the passive tensile load of steel strand will enlarge markedly unexpected fracture the when exceeding its ultimate load intensity.Therefore, adapt to the constant prestressing force that engineering rock mass ability of large deformation may occur and can keep prestress anchorage cable again preferably for making prestress anchorage cable have, thereby reach the maintenance engineering purpose of safety.Therefore, be necessary to develop a kind of self-checking device, make prestress anchorage cable when large deformation appears in Bolted Rock Masses, can extend automatically, thereby keep the anchor cable load to maintain a steady state value.
At present, domestic only have several devices that can regulate the prestress anchorage cable load that have, mainly be to adopt dish or bowl-type release pallet, compressible liner or compression ring, allow flexible measure such as pressing spring, or adapt to the large deformation of reinforcing rock mass by the devices such as ground tackle that improve steel strand.Relax the rapid increase that the engineering rock mass large deformation causes the anchor cable load though these devices can necessarily be gone up degree, all come with some shortcomings:
The increase of anchor cable load still can't be avoided and stop to the device of the adjusting anchor cable load that (1) has fully when adapting to the engineering rock mass large deformation;
It is very limited that the device self of the adjusting anchor cable load that (2) has can be regulated deflection, its allowable strain deficiency when the large deformation of reply engineering rock mass;
The device of the adjusting anchor cable load that (3) has can only be applicable to low loading condition because of directly utilizing the anchor cable steel strand anti-skid, make whole cable bolting body insufficient rigidity and cause waste.
Safety guard when (4) device self of regulating the anchor cable load a little lacks necessary ultimate elongation.
As seen, develop a kind of prestress anchorage cable active self adaptation constant-resistance lengthener of big elongation, high-drag, active self adaptation and safety margins protection of realizing for guaranteeing that geotechnical engineering reinforcing safety has obvious practical meaning and engineering demand.
Summary of the invention
At above-mentioned existing problems, the objective of the invention is to be to provide a kind of active self adaptation constant-resistance lengthener of prestress anchorage cable, have the load of initiatively regulating and control prestress anchorage cable under high load and the constant-resistance condition and increase, realization geotechnical engineering stream line is tackled the rock mass large deformation problem safely.
In order to achieve the above object, the present invention is achieved by the following technical solutions:
A kind of active self adaptation constant-resistance lengthener of prestress anchorage cable; Lengthener is by the heavy wall outer steel sleeve; Steel bushing in the thin-walled; The front end chuck; Rear end card handle; Nut forms; Heavy wall outer steel sleeve internal diameter is slightly smaller than the about 1~3mm of external diameter of steel bushing contact-segment in the thin-walled; Steel bushing noncontact section external diameter is less than the about 3mm of heavy wall outer steel sleeve internal diameter in the thin-walled; Heavy wall outer steel sleeve front end is with the lock dog of convex; Heavy wall outer steel sleeve rear end is connected with rear end card handle by screw thread; The front end chuck is connected with steel bushing in the thin-walled by nut; The front end chuck is with the front end lockhole of locking steel strand wires; Rear end card handle is with the rear end lockhole of locking steel strand wires; The constant-resistance principle of prestress anchorage cable self adaptation constant-resistance lengthener is that steel bushing is pressed into the heavy wall outer steel sleeve in heavy wall outer steel sleeve internal diameter is slightly smaller than under the condition of steel bushing external diameter 1~3mm in the thin-walled thin-walled; Thereby the contact-making surface in heavy wall outer steel sleeve and thin-walled between the steel bushing produces constant method to contact force; So just realized the specific elongation campaign between the steel bushing in heavy wall outer steel sleeve under the constant-resistance frictional resistance and the thin-walled; When external factor so that the anchor cable load increases and when surpassing constant-resistance; Specific elongation just can initiatively take place and move in the interior steel bushing of heavy wall outer steel sleeve and thin-walled, thereby in real time the anchor cable load is adjusted to previous level.
Owing to adopted technique scheme, the present invention to reform traditional anchor cable load adjusting device deficiency, had following advantage:
(1) load of initiatively regulating and control prestress anchorage cable under the constant-resistance increases: because the normal direction contact force is constant between heavy wall outer steel sleeve and the interior steel bushing of thin-walled, and the friction area of relative motion vertically is constant between the interior steel bushing of heavy wall outer steel sleeve and thin-walled, so can realize that initiatively the relative elongation between the steel bushing in heavy wall outer steel sleeve and the thin-walled automatically takes place self adaptation constant-resistance lengthener under constant resistance, thereby the working load of having realized prestress anchorage cable in real time is constant.
(2) constant-resistance effect stability under the high load: overflow to cooperate by the mistake between the steel bushing in heavy wall outer steel sleeve and the thin-walled and realized in heavy wall outer steel sleeve and the thin-walled between the steel bushing normal direction contact force of magnitude greatly, thereby realized its constant-resistance effect stability when friction factor is constant.
(3) security control of the elongation limit: the lock dog of the heavy wall outer steel sleeve front end by prestress anchorage cable self adaptation constant-resistance lengthener, can set the permission elongation of anchor cable, avoid anchor cable under the duty ceaselessly to extend and cause the engineering safety early warning untimely.
Description of drawings:
Fig. 1 is a kind of structural representation of active self adaptation constant-resistance lengthener of prestress anchorage cable;
Fig. 2 is a kind of A-A sectional drawing of active self adaptation constant-resistance lengthener of prestress anchorage cable;
Fig. 3 is a kind of B-B sectional drawing of active self adaptation constant-resistance lengthener of prestress anchorage cable.
Fig. 4 is a kind of C-C sectional drawing of active self adaptation constant-resistance lengthener of prestress anchorage cable.
Fig. 5 is a kind of D-D sectional drawing of active self adaptation constant-resistance lengthener of prestress anchorage cable.
Wherein: steel bushing 5, heavy wall outer steel sleeve 6, rear end card handle 7, rear end lockhole 8, noncontact section 9, contact-segment 10 in the lock dog 4 of nut 1, front end lockhole 2, front end chuck 3, convex, the thin-walled.
The specific embodiment:
Below in conjunction with Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5, the present invention is described in further detail:
A kind of active self adaptation constant-resistance lengthener of prestress anchorage cable; By nut 1; Front end lockhole 2; Front end chuck 3; The lock dog 4 of convex; Steel bushing 5 in the thin-walled; Heavy wall outer steel sleeve 6; Rear end card handle 7; Rear end lockhole 8 forms; It is characterized in that: heavy wall outer steel sleeve 6 internal diameters are than the slightly little about 1~3mm of contact-segment 10 external diameters of steel bushing in the thin-walled 5; Heavy wall outer steel sleeve 6 internal diameters are than the slightly about 3mm of noncontact section 9 external diameters of steel bushing in the thin-walled 5; Steel bushing 5 is pressed in heavy wall outer steel sleeve 6 holes by pressure jack instrument in the thin-walled; The friction slip that steel bushing 5 can take place along axis direction with heavy wall outer steel sleeve 6 in the thin-walled; Heavy wall outer steel sleeve 6 front ends are with the lock dog 4 of convex; Can stop steel bushing 5 and further generation specific elongation of heavy wall outer steel sleeve 6 in the thin-walled when contact-segment 10 otch of steel bushing 5 arrive at lock dog 4 in the thin-walled when the relative elongation between steel bushing in the thin-walled 5 and the heavy wall outer steel sleeve 6 reaches design elongation value; Heavy wall outer steel sleeve 6 rear ends are connected with rear end card handle 7 by screw thread; Reach the function of the interior steel bushing 5 of sealing thin-walled and heavy wall outer steel sleeve 6 inner chambers; Disk on the rear end card handle 7 is with eight lockholes 8; Realized that the anchor cable steel strand wires are connected with prestress anchorage cable active self adaptation constant-resistance lengthener one end by rear end lockhole 7; Front end chuck 3 couples together by steel bushing 5 in nut 1 and the thin-walled; Front end chuck 3 has realized that with eight front end lockholes 2 the anchor cable steel strand wires are connected with the prestress anchorage cable active self adaptation constant-resistance lengthener other end by front end lockhole 2.
The basic principle of the active self adaptation constant-resistance lengthener of prestress anchorage cable is under the condition of contact-segment 10 external diameters than the big slightly 1~3mm of internal diameter of heavy wall outer steel sleeve 6 of steel bushing 5 in thin-walled, after having utilized interior steel bushing 5 extruding of thin-walled to embed in the heavy wall outer steel sleeves 6, can produce very high contact force on the contact surface in thin-walled between steel bushing 5 and the heavy wall outer steel sleeve 6, when the friction factor of contact surface between steel bushing in the thin-walled 5 and the heavy wall outer steel sleeve 6 is constant, just can realize producing constant high sliding-frictional resistance along axis direction.If setting the constant-resistance load of prestress anchorage cable self adaptation constant-resistance lengthener is N
oAnd make the rigidity of heavy wall outer steel sleeve 6 obviously greater than the modulus of elasticity of steel bushing in the thin-walled 5, elastic model (E) and the poisson's ratio (μ) of steel bushing 5 in the known thin-walled, and friction factor (f) between interior steel bushing 5 of thin-walled and the heavy wall outer steel sleeve 6 are so at the internal diameter (d of heavy wall outer steel sleeve 6
1) and thin-walled under the definite situation of steel bushing thickness (n), the contact-segment 10 external diameter (d of steel bushing 5 in the thin-walled
2) and internal diameter (d
3) can calculate acquisition by formula 1 and formula 2:
d
3=d
2-n (2)
Wherein: inner diameter d
1, outside diameter d
2, inner diameter d
3, the constant-resistance load is N
o, friction factor is f, elastic model E, steel bushing thickness n in the poisson's ratio μ, thin-walled.
The concrete use of the present invention follows these steps to carry out:
(1) determined the constant-resistance load of active self adaptation constant-resistance lengthener of prestress anchorage cable after, under the known condition of heavy wall outer steel sleeve 6 internal diameters, modulus of elasticity (E), poisson's ratio (μ), thickness (n) according to 5 materials of steel bushing in the thin-walled, and the friction factor (f) between steel bushing 5 and the heavy wall outer steel sleeve 6 in the thin-walled, can calculate the contact-segment 10 external diameter (d of steel bushing 5 in the thin-walled according to formula 1 and formula 2
2) and internal diameter (d
3), and produce steel bushing 5 in the thin-walled in view of the above;
(2) steel bushing in the thin-walled 5 is pressed in the heavy wall outer steel sleeve 6 fully by aid, and the contact-segment 10 of the interior steel bushing 5 of assurance thin-walled and the back end in contact of heavy wall outer steel sleeve 6, for taking place between steel bushing in the thin-walled 5 and the heavy wall outer steel sleeve 6, the relative elongation campaign leaves the setting stroke;
(3) rear end card handle 7 is connected by the rear end of screw thread with heavy wall steel bushing 6;
(4) the anchor cable steel strand with an end are installed in the front end lockhole 2 of front end chuck 3 by lockset;
(5) the anchor cable steel strand with the other end are installed in the front end lockhole 7 of rear end card handle 7 by lockset, thereby realized the installation of the active self adaptation constant-resistance lengthener of prestress anchorage cable, load takes place when prestress anchorage cable is worked uprushes, then the active self adaptation constant-resistance lengthener of prestress anchorage cable just can extend automatically, reaches the purpose of regulating the anchor cable load.