CN102174812B - An Active Adaptive Constant Resistance Extender for Prestressed Anchor Cable - Google Patents

Abstract

The invention discloses an active self-adaptive constant-resistance extender for prestressed anchor cables. The inner diameter of the thick-walled outer steel sleeve, the front end of the thick-walled outer steel sleeve has an inwardly convex lock block, the rear end of the thick-walled outer steel sleeve is connected to the rear end handle through a threaded buckle, and the front chuck is connected to the thin-walled inner steel sleeve through a nut , the front chuck has a front lock hole for locking the steel strand, and the rear handle has a rear lock hole for locking the steel strand. The disc on the rear end handle has eight lock holes, and the anchor cable steel strand is connected with one end of the prestressed anchor cable extender through the rear end lock holes. The front-end chuck is connected with the thin-walled inner steel sleeve through a nut, and the front-end chuck has eight front-end lock holes, and the anchor cable steel strand is connected with the other end of the prestressed anchor cable extender through the front-end lock holes. The structure is simple, the use is convenient, the load growth of the prestressed anchor cable is actively adjusted under constant resistance, the constant resistance effect is stable under high load, and the elongation limit is safely controlled.

Description

An Active Adaptive Constant Resistance Extender for Prestressed Anchor Cable

technical field

The invention relates to the field of rock mass safety support in geotechnical engineering, and more specifically relates to an active self-adaptive constant resistance extender for prestressed anchor cables, which is suitable for using prestressed anchor cables to reinforce rock in slope engineering or underground engineering. body.

Background technique

Restricted by my country's complex engineering geological conditions, hydropower, transportation, resources, energy, national defense and other large-scale geotechnical engineering constructions, such as hydropower development in the west, south-to-north water diversion, deep mining, oil/gas extraction, strategic energy storage, hydropower slopes, underground Military bunker projects, etc., all involve the support technology of using prestressed anchor cables to reinforce engineering rock mass. However, engineering rock mass usually undergoes increasing deformation release over time due to the stress unloading effect of the rock mass and the aging deformation characteristics of the rock mass itself. However, the prestressed anchor cables installed on engineering rock masses are usually unable to adaptively coordinate with the deformation growth of such anchored rock masses, which leads to the continuous increase of the anchor cable strand load over time, causing it to exceed the anchorage. The anchor cable steel strand breaks due to the ultimate strength of the cable itself. For example, in underground engineering, during the construction of the underground powerhouse of the Ertan Hydropower Station in my country, large deformations were induced due to sudden brittle failure of the engineering rock mass, resulting in the breakage of multiple anchor cables; The partition wall also fractured due to the continuous deformation of the rock mass, which caused the load of the steel strand of the anchor cable to exceed the ultimate strength. In slope engineering, the engineering rock mass undergoes relaxation and large deformation under long-term natural force and human disturbance, which also leads to the failure of the anchor cable because the anchor cable cannot adapt to the large deformation of the rock mass and its load exceeds its ultimate strength value. , endangering the safety of slope engineering.

In general, the root cause of the large deformation of the engineering rock mass that the anchor cable load cannot adapt to the deformation of the rock mass is the low elongation of the anchor cable steel strand. According to my country's national standard "Steel Strands for Prestressed Concrete" (GB/T5224-1995), the steel strands of prestressed anchor cables are all high-strength and low-elongation steels. Since this high-strength steel strand has no obvious plastic deformation section, when the engineering rock mass it is anchored to undergoes large deformation, the passive tension load of the steel strand will increase significantly, and will suddenly increase when the ultimate load strength is exceeded. fracture. Therefore, in order to make the prestressed anchor cable have the ability to adapt to the large deformation that may occur in the engineering rock mass, and to better maintain the constant prestress of the prestressed anchor cable, so as to achieve the purpose of maintaining engineering safety. Therefore, it is necessary to develop an automatic adjustment device, so that the prestressed anchor cable can automatically elongate when the anchorage rock mass undergoes large deformation, so as to maintain the anchor cable load at a constant value.

At present, there are only a few devices with adjustable prestressed anchor cable loads in China, mainly using flexible measures such as dish-shaped or bowl-shaped pressure relief trays, compressible liners or compression rings, and compression springs, or through improved steel strands. Line anchors and other devices are used to adapt to the large deformation of the reinforced rock mass. Although these devices can relieve the sharp increase of the anchor cable load caused by the large deformation of the engineering rock mass to a certain extent, they all have some shortcomings:

(1) Some devices for adjusting the load of the anchor cable cannot completely avoid and prevent the increase of the load of the anchor cable when adapting to the large deformation of the engineering rock mass;

(2) Some devices for adjusting the load of anchor cables have very limited adjustable deformation, and their allowable deformation is insufficient when dealing with large deformation of engineering rock mass;

(3) Some devices for adjusting the anchor cable load can only be applied to low load conditions because they directly use the anchor cable steel strands to prevent slipping, so that the rigidity of the entire anchor cable support body is insufficient and wasteful.

(4) The device that adjusts the load of the anchor cable itself lacks the necessary safety protection device when the ultimate elongation is reached.

It can be seen that the development of an active adaptive constant resistance extender for prestressed anchor cables that can achieve large elongation, high resistance, active self-adaptation and safety limit protection has obvious practical significance and engineering significance for ensuring the safety of geotechnical engineering reinforcement. need.

Contents of the invention

In view of the above existing problems, the purpose of the present invention is to provide an active self-adaptive constant resistance extender for prestressed anchor cables, which can actively regulate the load growth of prestressed anchor cables under high load and constant resistance conditions, and realize geotechnical The anchor cable in the project can safely deal with the large deformation of the rock mass.

In order to achieve the above object, the present invention is achieved through the following technical solutions:

An active self-adaptive constant resistance extender for prestressed anchor cables. The extender is composed of a thick-walled outer steel sleeve, a thin-walled inner steel sleeve, a front chuck, a rear end chuck, and a nut. The inner diameter of the thick-walled outer steel sleeve is Slightly smaller than the outer diameter of the contact section of the thin-walled inner steel sleeve by about 1-3 mm, the outer diameter of the non-contact section of the thin-walled inner steel sleeve is about 3 mm smaller than the inner diameter of the thick-walled outer steel sleeve, and the front end of the thick-walled outer steel sleeve has an inwardly convex locking block , the rear end of the thick-walled outer steel sleeve is connected with the rear-end clamping handle through a screw, the front-end chuck is connected with the thin-walled inner steel sleeve through a nut, the front-end chuck has a front-end lock hole for locking the steel strand, and the rear-end clamping handle has a There is a lock hole at the rear end of the locking steel strand, and the constant resistance principle of the self-adaptive constant resistance extender for prestressed anchor cables is that the inner diameter of the thick-walled outer steel sleeve is slightly smaller than the outer diameter of the thin-walled inner steel sleeve by 1 to 3 mm. The thin-walled inner steel sleeve is pressed into the thick-walled outer steel sleeve, so that a constant normal contact force is generated on the contact surface between the thick-walled outer steel sleeve and the thin-walled inner steel sleeve, so that the thick-walled steel sleeve under constant frictional resistance is realized. The relative elongation between the outer steel sleeve and the thin-walled inner steel sleeve, when the external factors increase the anchor cable load and exceed the constant resistance, the thick-walled outer steel sleeve and the thin-walled inner steel sleeve can actively undergo relative elongation Move, so as to adjust the anchor cable load to the original level in real time.

Due to the adoption of the above-mentioned technical scheme, the present invention has reformed the deficiencies of the traditional anchor cable load regulating device, and has the following advantages:

(1) Actively adjust the load growth of the prestressed anchor cable under constant resistance: due to the constant normal contact force between the thick-walled outer steel jacket and the thin-walled inner steel jacket, and the The friction area of relative motion along the axial direction is constant, so the active adaptive constant resistance extender can automatically generate relative elongation between the thick-walled outer steel sleeve and the thin-walled inner steel sleeve under constant resistance, thereby realizing real-time The working load of the prestressed anchor cable is constant.

(2) The constant resistance effect is stable under high load: through the overflow fit between the thick-walled outer steel sleeve and the thin-walled inner steel sleeve, a large number of normal contacts between the thick-walled outer steel sleeve and the thin-walled inner steel sleeve are realized Force, so that the constant resistance effect is stable when the friction coefficient is constant.

(3) Safety control of elongation limit: through the lock block at the front end of the thick-walled outer steel sleeve of the prestressed anchor cable self-adaptive constant resistance extender, the allowable elongation of the anchor cable can be set to avoid the anchor under working condition. The endless elongation of the cable leads to untimely engineering safety warning.

Description of drawings:

Fig. 1 is a structural schematic diagram of an active self-adaptive constant resistance extender for a prestressed anchor cable;

Fig. 2 is the A-A sectional view of the active self-adaptive constant resistance stretcher of a kind of prestressed anchor cable;

Fig. 3 is a B-B sectional view of an active self-adaptive constant resistance stretcher for a prestressed anchor cable.

Fig. 4 is a C-C sectional view of an active self-adaptive constant resistance stretcher for a prestressed anchor cable.

Fig. 5 is a D-D sectional view of an active self-adaptive constant resistance stretcher for a prestressed anchor cable.

Among them: nut 1, front lock hole 2, front chuck 3, inner convex lock block 4, thin-walled inner steel sleeve 5, thick-walled outer steel sleeve 6, rear end handle 7, rear end lock hole 8, non-contact Segment 9, Contact Segment 10.

Detailed ways:

Below in conjunction with Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5, the present invention is described in further detail:

An active self-adaptive constant resistance extender for prestressed anchor cables, comprising a nut 1, a front lock hole 2, a front chuck 3, an inner convex lock block 4, a thin-walled inner steel sleeve 5, and a thick-walled outer steel sleeve 6 , a rear end handle 7, and a rear end lock hole 8, characterized in that the inner diameter of the thick-walled outer steel sleeve 6 is slightly smaller than the outer diameter of the contact section 10 of the thin-walled inner steel sleeve 5 by about 1 to 3mm, and the thick-walled outer steel sleeve 6. The inner diameter is slightly about 3mm than the outer diameter of the non-contact section 9 of the thin-walled inner steel sleeve 5. The thin-walled inner steel sleeve 5 is pressed into the hole 6 of the thick-walled outer steel sleeve by a pressure jack tool. The thin-walled inner steel sleeve 5 can be connected with The thick-walled outer steel sleeve 6 frictionally slides along the axial direction, and the front end of the thick-walled outer steel sleeve 6 has an inwardly convex locking block 4. When the relative elongation between the thin-walled inner steel sleeve 5 and the thick-walled outer steel sleeve 6 When the amount reaches the design elongation value, the contact section 10 of the thin-walled inner steel sleeve 5 can prevent the thin-walled inner steel sleeve 5 and the thick-walled outer steel sleeve 6 from further relative elongation when it reaches the lock block 4, and the thick-walled outer steel sleeve 6. The rear end is connected with the rear end handle 7 through a screw thread to achieve the function of closing the inner cavity of the thin-walled inner steel sleeve 5 and the thick-walled outer steel sleeve 6. The disc on the rear end handle 7 has eight rear end locks Hole 8 realizes that the steel strand of the anchor cable is connected to one end of the active adaptive constant resistance extender of the prestressed anchor cable through the rear end lock hole 8, the front chuck 3 is connected with the thin-walled inner steel sleeve 5 through the nut 1, and the front end The chuck 3 has eight front-end keyholes 2, which realize the connection of the steel strand of the anchor cable to the other end of the active self-adaptive constant resistance extender of the prestressed anchor cable through the front-end keyholes 2.

The basic principle of the active adaptive constant resistance extender for prestressed anchor cables is that the outer diameter of the contact section 10 of the thin-walled inner steel sleeve 5 is slightly larger than the inner diameter of the thick-walled outer steel sleeve 6 by 1 to 3 mm. After the thin-walled inner steel sleeve 5 is extruded and embedded in the thick-walled outer steel sleeve 6, a high contact force can be generated on the contact surface between the thin-walled inner steel sleeve 5 and the thick-walled outer steel sleeve 6. When the thin-walled inner steel sleeve 5 When the friction coefficient of the contact surface between the steel sleeve 5 and the thick-walled outer steel sleeve 6 is constant, a constant high sliding frictional resistance along the axial direction can be realized. If the constant resistance load of the self-adaptive constant resistance extender of the prestressed anchor cable is set as N _o , and the stiffness of the thick-walled outer steel sheath 6 is significantly greater than the elastic modulus of the thin-walled inner steel sheath 5, it is known that the thin-walled inner sheath The elastic model (E) and Poisson's ratio (μ) of the steel sleeve 5, and the friction coefficient (f) between the thin-walled inner steel sleeve 5 and the thick-walled outer steel sleeve 6, then the inner diameter of the thick-walled outer steel sleeve 6 (d ₁ ) and the thickness (n) of the thin-walled inner steel sleeve are determined, the outer diameter (d ₂ ) and inner diameter (d ₃ ) of the contact section 10 of the thin-walled inner steel sleeve 5 can be calculated according to formula 1 and formula 2:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="d"\; filenames="HDA0000049194730000011.png,HDA0000049194730000021.png"\; state="\{\{state\}\}">d</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

d ₃ =d ₂ −n (2)

Among them: inner diameter d ₁ , outer diameter d ₂ , inner diameter d ₃ , constant resistance load is N _o , coefficient of friction is f, elastic model E, Poisson's ratio μ, thickness of thin-walled inner steel sleeve n.

The specific use of the present invention is carried out according to the following steps:

(1) After determining the constant resistance load of the active adaptive constant resistance extender of the prestressed anchor cable, under the condition that the inner diameter of the thick-walled outer steel sleeve 6 is known, according to the elastic modulus of the material of the thin-walled inner steel sleeve 5 (E), Poisson's ratio (μ), thickness (n), and the friction coefficient (f) between the thin-walled inner steel sleeve 5 and the thick-walled outer steel sleeve 6 can be calculated according to formula 1 and formula 2 The outer diameter (d ₂ ) and inner diameter (d ₃ ) of the contact section 10 of the inner steel sleeve 5, and the thin-walled inner steel sleeve 5 is produced accordingly;

(2) Completely press the thin-walled inner steel sleeve 5 into the thick-walled outer steel sleeve 6 through an auxiliary tool, and ensure that the contact section 10 of the thin-walled inner steel sleeve 5 is in contact with the rear end of the thick-walled outer steel sleeve 6. The relative elongation movement between the inner steel sleeve 5 and the thick-wall outer steel sleeve 6 leaves a set stroke;

(3) the rear end handle 7 is connected with the rear end of the thick-walled steel sleeve 6 through a screw;

(4) install the anchor cable steel strand at one end in the front lock hole 2 of the front chuck 3 through the lockset;

(5) The anchor cable steel strand at the other end is installed in the rear end lock hole 8 of the rear end handle 7 through the lock, thereby realizing the installation of the active self-adaptive constant resistance extender of the prestressed anchor cable. When the load of the stressed anchor cable increases suddenly, the active self-adaptive constant resistance extender of the prestressed anchor cable can be automatically extended to achieve the purpose of adjusting the load of the anchor cable.

Claims (3)

1. the active self adaptation constant-resistance lengthener of a prestress anchorage cable; It comprises steel bushing (5), heavy wall outer steel sleeve (6), rear end card handle (7) in front end chuck (3), the thin-walled; It is characterized in that: heavy wall outer steel sleeve (6) internal diameter is less than the external diameter of the contact-segment (10) of steel bushing in the thin-walled (5); steel bushing (5) noncontact section (9) external diameter is less than heavy wall outer steel sleeve (6) internal diameter in the thin-walled, and heavy wall outer steel sleeve (6) front end has the lock dog (4) of convex, and heavy wall outer steel sleeve (6) rear end is connected with rear end card handle (7) through screw thread; front end chuck (3) is connected through the interior steel bushing (5) of nut (1) and thin-walled; front end chuck (3) has the front end lockhole (2) that locks steel strand, and rear end card handle (7) has the rear end lockhole (8) that locks steel strand, and the constant-resistance load of setting 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); The elastic model and the poisson's ratio of steel bushing (5) in the known thin-walled, and friction factor between steel bushing (5) and the heavy wall outer steel sleeve (6) in the thin-walled, the thickness of steel bushing (5) is confirmed under the situation in the internal diameter of heavy wall outer steel sleeve (6) and thin-walled; the external diameter of the contact-segment (10) of the interior steel bushing (5) of thin-walled and internal diameter can be by formula A and formula B calculating acquisitions

$d_2=d_1+\frac{N_o}{f}(d_1-n)\frac{1-\mathrm{\&mu;}}{E}(\frac{n}{d_1+n}+\frac{\mathrm{\&mu;}}{1-\mathrm{\&mu;}})---\left(A\right)$

d ₃＝d ₂-n (B)

Wherein: heavy wall outer steel sleeve inner diameter d ₁, the contact-segment outside diameter d of steel bushing in the thin-walled ₂, the contact-segment inner diameter d of steel bushing in the thin-walled 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.

2. the active self adaptation constant-resistance lengthener of a kind of prestress anchorage cable according to claim 1; It is characterized in that: the disk on the described rear end card handle (7) has eight rear end lockholes (8), and the anchor cable steel strand are connected with prestress anchorage cable active self adaptation constant-resistance lengthener one end through rear end lockhole (8).

3. the active self adaptation constant-resistance lengthener of a kind of prestress anchorage cable according to claim 1; It is characterized in that: described front end chuck (3) is connected through the interior steel bushing (5) of nut (1) and thin-walled; Front end chuck (3) has eight front end lockholes (2), and the anchor cable steel strand are connected with the prestress anchorage cable active self adaptation constant-resistance lengthener other end through front end lockhole (2).

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