Chemical bolt suitable for tunnel rail side equipment installation and installation strength evaluation method

Abstract

The invention discloses a chemical bolt suitable for tunnel rail side equipment installation and an installation strength evaluation method. The influence of piston wind on equipment in a tunnel cannot be ignored, and serious safety problems may be caused. The device comprises inverted conical teeth, a sleeve is connected to the inverted conical teeth, and a screw is connected to the sleeve; the inverted conical teeth and the sleeve are arranged in a base material on the tunnel rail side, and anchoring glue is filled between the inverted conical teeth and the base material and between the sleeve and the base material. And the screw rod is connected with tunnel rail side equipment through a flat washer and a nut. The bolt adopts a double anchoring mechanism, and combines the double effects of chemical anchoring and mechanical anchoring; wherein the chemical anchoring is realized through a chemical binder, and the mechanical anchoring is realized through the mechanical occlusion effect of the inverted conical teeth and the sleeve; the double anchoring mechanism not only can effectively resist continuous reciprocating drawing force generated by the pneumatic effect when the train passes, but also obviously improves the anti-fatigue durability of the bonding structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel track-side equipment installation, and particularly relates to a chemical bolt suitable for tunnel track-side equipment installation and an installation strength evaluation method. Background Art

[0002] During the process of a train passing through a tunnel at high speed, the air viscous effect causes the air in the boundary layer to move synchronously with the train, thereby forming a strong train wind, which poses a significant safety hazard to the operating personnel and built-in equipment in the tunnel and seriously threatens the running safety of the train. It is particularly worth noting that the train wind caused by the train wake is often more violent than when the train passes directly, and its influence is mainly concentrated in the area on one side of the tunnel close to the train, while the area on the side far from the train is relatively less affected; especially on the tunnel wall surface close to the train side, the intensity of the train wind significantly exceeds that on the side far from the train. The distribution of the train wind in the tunnel shows obvious position differences. In the case of a single train passing through the tunnel, the maximum peak value of the train wind on the side close to the train is almost the same in the front and middle parts of the tunnel; however, on the side far from the train, the maximum peak value of the train wind in the front part of the tunnel is significantly higher than that in the middle part of the tunnel. For the situation of train meeting in the tunnel, the maximum peak value of the train wind on the side close to the train significantly increases in the middle part of the tunnel, exceeding that in the front part; while the maximum peak value of the train wind on the side far from the train is roughly the same in the front and middle parts of the tunnel. In addition, the piston wind generated when the train runs in the tunnel shows regular periodic changes as the train moves forward. Given the current high-speed operation and high-density train operation of trains, the long-term impact of the piston wind on the equipment in the tunnel and the equipment in the piston air duct cannot be ignored and may cause serious safety problems. To sum up, in view of the significant impact of the wind formed during the train running on the track-side equipment, it is particularly important to design a track-side equipment installation bolt that can effectively resist the pneumatic pulling-out effect of the train and prevent the track-side equipment from falling off, thereby avoiding train operation safety accidents. Summary of the Invention

[0003] In order to make up for the deficiencies of the prior art, the present invention provides a chemical bolt suitable for tunnel track-side equipment installation and an installation strength evaluation method, which can effectively resist the pneumatic pulling-out effect of the train and prevent the track-side equipment from falling off, thereby avoiding train operation safety accidents.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A chemical bolt suitable for tunnel track-side equipment installation, comprising an inverted cone tooth, a sleeve is connected to the inverted cone tooth, and a screw rod is connected to the sleeve;

[0006] The inverted cone tooth and the sleeve are arranged in the base material on the tunnel track side, and an anchoring glue is filled between the inverted cone tooth and the sleeve and the base material;

[0007] The screw is connected to the tunnel track side equipment through flat washers and nuts.

[0008] Furthermore, the inverted taper teeth include a plurality of connecting segments, and the connecting segments are trapezoidal.

[0009] Furthermore, a spring washer is arranged at the nut connection.

[0010] A method for evaluating the installation strength of a chemical bolt suitable for the installation of tunnel track side equipment, comprising the following steps:

[0011] Step 1: Determine the basic anchorage length of the bolt required for the installation of the tunnel track side equipment;

[0012] Step 2: Determine the minimum bonding stress and cyclic loss stress required for the installation of the tunnel track side equipment;

[0013] Step 3: Determine the bonding strength of the bolt required for the installation of the tunnel track side equipment;

[0014] Step 4: Calculate the pull-out bearing capacity of the chemical bolt;

[0015] Step 5: Check whether the chemical bolt will be pulled out under the action of the reciprocating pull-out cyclic force formed by the piston wind on the equipment in the tunnel.

[0016] Furthermore, in the said Step 1, determining the basic anchorage length of the bolt specifically is:

[0017]

[0018] wherein, l a is the basic anchorage length of the bolt; α is the bolt shape coefficient, taking α = 0.14; f y is the design value of the tensile strength of the bolt; f t is the design value of the axial tensile strength of the base concrete. When the strength grade of the base concrete is higher than C60, it is taken as C60; d is the nominal diameter of the bolt.

[0019] Furthermore, in the said Step 2, the specific calculation method for the minimum bonding stress required for the installation of the tunnel track side equipment is:

[0020]

[0021] τ = min{τ max , σ b , 1.39} (4)

[0022] In the formula, τ max is the maximum bonding stress; σ b is the normal stress; f c' is the standard value of the axial compressive strength of concrete; d is the nominal diameter of the bolt; τ is the minimum bonding stress required for the installation of tunnel track-side equipment.

[0023] Furthermore, in the said step 2, the calculation method of the cyclic loss stress is as follows:

[0024] τ cycle = 0.6τ (5)

[0025] where τ cycle is the cyclic loss stress required for the installation of tunnel track-side equipment.

[0026] Furthermore, in the said step 3, the specific method for calculating the bonding strength of the bolts required for the installation of tunnel track-side equipment is as follows:

[0027]

[0028] In the formula: P is the bonding strength of the bolts required for the installation of tunnel track-side equipment; d is the nominal diameter of the bolt; l a is the basic anchorage length of the bolt.

[0029] Furthermore, in the said step 4, the calculation of the pull-out bearing capacity of the chemical bolts is specifically as follows:

[0030] (1) The pull-out bearing capacity of the chemical bolts first needs to consider the tensile strength of the bolt material itself and is calculated according to formula (7);

[0031]

[0032] In the formula, F b is the pull-out bearing capacity of the bolt; d is the nominal diameter of the bolt; σ is the tensile strength of the bolt material;

[0033] (2) The chemical bonding bearing capacity formed by the anchoring adhesive is calculated according to formula (8);

[0034] F c = C × l d (8)

[0035] In the formula, F c is the chemical bonding bearing capacity; C is the chemical anchor force coefficient; l d is the anchorage length of the bolt;

[0036] (3) The locking force formed by the inverted conical tooth 1 is calculated according to formula (9);

[0037]

[0038] In the formula, F s is the locking force; c is the locking force coefficient, which is determined according to the grade and type of the bolt (for grade 1 bolts, c = 3.0, and for grade 2 bolts, c = 2.4); fcu is the compressive strength of the substrate concrete cube; h ef is the effective anchorage depth of the bolt;

[0039] (4) The comprehensive bearing capacity is calculated according to formula (10).

[0040] F = min(F b , F c , F s ) (10).

[0041] Furthermore, step 5 is specifically as follows:

[0042] Compare the magnitudes of P and F, and P and F should satisfy:

[0043] P < βF (11)

[0044] In the formula, β is the safety factor, and β < 1.

[0045] Advantages of the present invention:

[0046] 1) The bolts of the present invention adopt a unique dual anchoring mechanism, combining the dual effects of chemical anchoring and mechanical anchoring; among them, chemical anchoring is achieved through a chemical binder, while mechanical anchoring is achieved through the mechanical biting action of the inverted cone teeth and the casing; this dual anchoring mechanism can not only effectively resist the continuous reciprocating pulling force generated by the aerodynamic effect during train passage, but also significantly improve the anti-fatigue durability of the bonded structure; the chemical bolts of the present invention show higher reliability and stability in complex load environments, and are especially suitable for the high-strength installation requirements of tunnel track-side equipment;

[0047] 2) The present invention combines the continuous reciprocating pulling effect caused by the aerodynamic effect during train passage, the calculation of the anchoring effect of chemical anchor bolts, and the calculation of the mechanical anchoring formed by the inverted cone teeth and the casing, and proposes an installation strength evaluation method for chemical bolts; this method comprehensively considers the synergistic effect of chemical anchoring force and mechanical anchoring force, and can accurately calculate the installation strength of composite anchoring bolts under actual working conditions; through this evaluation method, engineering personnel can scientifically determine the installation parameters of the bolts to ensure the reliability and safety of equipment installation. Brief Description of the Drawings

[0048] Figure 1 is a schematic structural diagram of the chemical bolt of the present invention;

[0049] Figure 2 is an installation schematic diagram of the present invention;

[0050] In the figure, 1, inverted cone teeth; 2, casing; 3, screw; 4, flat washer; 5, spring washer; 6, nut. Specific Embodiments

[0051] The present invention will be described in detail below in conjunction with specific embodiments.

[0052] As Figure 1 , 2 shown, the present invention provides a chemical bolt suitable for installing tunnel track-side equipment, which has both the bonding force of the anchoring glue of the chemical bolt and the locking effect formed by the dovetail under-reaming and the inverted cone; it includes an inverted cone tooth 1, a sleeve 2 is connected to the inverted cone tooth 1, and a screw 3 is connected to the sleeve 2; the inverted cone tooth 1 and the sleeve 2 are arranged in the substrate on the tunnel track side, and the anchoring glue is filled between the inverted cone tooth 1 and the sleeve 2 and the substrate; the screw 3 is connected to the tunnel track-side equipment through a flat washer 4, a spring washer 5 and a nut 6. The inverted cone tooth 1 includes a plurality of connecting segments, and the connecting segments are trapezoidal.

[0053] The present invention also provides a method for evaluating the installation strength of a chemical bolt suitable for installing tunnel track-side equipment, including the following steps:

[0054] Step 1: Determine the basic anchorage length of the bolt required for installing tunnel track-side equipment;

[0055] Step 2: Determine the minimum bonding stress and cyclic loss stress required for installing tunnel track-side equipment;

[0056] Step 3: Determine the bonding strength of the bolt required for installing tunnel track-side equipment;

[0057] Step 4: Calculate the pull-out bearing capacity of the chemical bolt;

[0058] Step 5: Check whether the chemical bolt will be pulled out under the action of the reciprocating pull-out cyclic force formed by the piston wind on the equipment in the tunnel.

[0059] 1) In step 1, to determine the basic anchorage length of the bolt, specifically:

[0060] The formula for calculating the basic anchorage length of the bolt is:

[0061]

[0062] Among them, l a is the basic anchorage length of the bolt; α is the bolt shape coefficient, taking α = 0.14; f y is the design value of the tensile strength of the bolt; f t is the design value of the axial tensile strength of the substrate concrete. When the strength grade of the substrate concrete is higher than C60, it is taken as C60; d is the nominal diameter of the bolt.

[0063] 2) In step 2, the specific calculation method for the minimum bonding stress required for installing tunnel track-side equipment is:

[0064]

[0065] τ = min{τ max , σ b , 1.39} (4)

[0066] where τ max is the maximum bond stress; σ b is the normal stress; f c ' is the standard value of the axial compressive strength of the substrate concrete; d is the nominal diameter of the bolt; τ is the minimum bond stress required for the installation of tunnel track-side equipment.

[0067] 3) In step 2, the calculation method of the cyclic loss stress is as follows:

[0068] When the train runs in the tunnel, the piston wind generated shows regular periodic changes as the train progresses. The piston wind generates a reciprocating pulling cyclic force on the equipment in the tunnel and the equipment in the piston air duct.

[0069] τ cycle = 0.6τ (5)

[0070] where τ cycle is the cyclic loss stress required for the installation of tunnel track-side equipment.

[0071] 4) In step 3, the specific method for calculating the bond strength of the bolts required for the installation of tunnel track-side equipment is as follows:

[0072]

[0073] In the formula: P is the bond strength of the bolts required for the installation of tunnel track-side equipment; d is the nominal diameter of the bolt; l a is the basic anchorage length of the bolt.

[0074] 5) In step 4, the calculation of the pull-out bearing capacity of the chemical bolts is as follows:

[0075] ① First, the pull-out bearing capacity of the chemical bolts needs to consider the tensile strength of the bolt material itself and is calculated according to formula 7;

[0076]

[0077] In the formula, F b is the pull-out bearing capacity of the bolt; d is the nominal diameter of the bolt; σ is the tensile strength of the bolt material;

[0078] ② The chemical bond bearing capacity formed by the anchoring adhesive is calculated according to formula 8;

[0079] F c = C × l d (8)

[0080] In the formula, F c is the chemical bond bearing capacity; C is the chemical anchor force coefficient; ld is the anchorage length of the bolt;

[0081] ③ The locking force formed by the inverted taper teeth 1 is calculated according to Formula 9;

[0082]

[0083] In the formula, F s is the locking force; c is the locking force coefficient, which is determined according to the grade and type of the bolt. For grade 1 bolts, c = 3.0, and for grade 2 bolts, c = 2.4; f cu is the cube compressive strength of the base concrete; h ef is the effective anchorage depth of the bolt;

[0084] ④ The comprehensive bearing capacity is calculated according to Formula 10.

[0085] F = min(F b , F c , F s ) (10).

[0086] Take the minimum value of the tensile strength of the bolt material, the chemical bonding bearing capacity formed by the anchoring adhesive, and the locking force formed by the inverted conical under-reamed part as the pull-out bearing capacity of the chemical bolt.

[0087] 6) Step 5 is specifically as follows:

[0088] Compare the magnitudes of P and F to check whether the chemical bolt will be pulled out under the action of the reciprocating pull-out cyclic force formed by the piston wind on the equipment in the tunnel.

[0089] P < βF (11)

[0090] In the formula, β is the safety factor, β < 1. At this time, the pull-out bearing capacity F of the chemical bolt is greater than the bonding strength P of the bolt, and the bolt will not be pulled out under the action of the reciprocating pull-out cyclic force, and the tunnel track-side equipment is installed stably.

[0091] The content of the present invention is not limited to the examples listed. Any equivalent transformation of the technical solution of the present invention adopted by those of ordinary skill in the art by reading the specification of the present invention is covered by the claims of the present invention.

Claims

1. A chemical bolt suitable for installing tunnel trackside equipment, characterized in that: It comprises an inverted cone tooth (1), a sleeve (2) is connected to the inverted cone tooth (1), and a screw rod (3) is connected to the sleeve (2); The inverted cone teeth (1) and the sleeve (2) are arranged in a base material on the side of the tunnel rail, and anchoring glue is filled between the inverted cone teeth (1) and the sleeve (2) and the base material; The screw rod (3) is connected to the tunnel rail side equipment via a flat washer (4) and a nut (6).

2. According to claim 1, a chemical bolt suitable for installing tunnel track side equipment is characterized in that: The inverted cone tooth (1) comprises a plurality of connecting sections, and the connecting sections are in a trapezoidal shape.

3. The chemical bolt suitable for installing tunnel trackside equipment according to claim 2, characterized in that: A spring washer (5) is provided at the connection point of the nut (6).

4. A method for evaluating the installation strength of chemical bolts used for installing tunnel trackside equipment, characterized in that: The steps include: Step 1: Determine the basic anchoring length of bolts required for the installation of tunnel trackside equipment; Step 2: Determine the minimum bonding stress and cyclic loss stress required for the installation of tunnel trackside equipment; Step 3: Determine the bond strength of the bolts required for tunnel trackside equipment installation; Step 4: Calculate the pull-out capacity of the chemical bolt; Step 5: Verify whether the chemical bolts will be pulled out under the action of the reciprocating pulling cycle force generated by the piston wind on the equipment in the tunnel.

5. The installation strength assessment method of chemical bolts suitable for tunnel trackside equipment installation according to claim 4, characterized in that: In step 1, the basic anchoring length of the bolt is determined as follows: Among them, l a is the basic anchoring length of the bolt; α is the bolt shape coefficient, taking α=0.14; f y is the design value of the tensile strength of the bolt; f t It is the design value of the axial tensile strength of the base concrete. When the strength grade of the base concrete is higher than C60, the value is taken according to C60; d is the nominal diameter of the bolt.

6. The installation strength evaluation method of chemical bolts suitable for tunnel trackside equipment installation according to claim 5, characterized in that: In step 2, the specific calculation method of the minimum bonding stress required for the installation of the tunnel track side equipment is: τ=min{τ max ,s b ,1.39}(4) In the formula, τ max is the maximum bonding stress; b is the normal stress; f c ' is the standard value of concrete axial compressive strength; d is the nominal diameter of the bolt; τ is the minimum bonding stress required for the installation of tunnel track side equipment.

7. The method for evaluating the installation strength of chemical bolts suitable for installation of tunnel trackside equipment according to claim 6, characterized in that: In step 2, the cycle loss stress calculation method is: t cycle =0.6τ(5) Among them, τ cycle Cyclic loss stresses required for tunnel trackside equipment installation.

8. The method for evaluating the installation strength of chemical bolts suitable for installation of tunnel trackside equipment according to claim 7, characterized in that: In step 3, the specific method for calculating the bonding strength of the bolts required for installing the tunnel track side equipment is: Where: P is the bond strength of the bolts required for the installation of the tunnel trackside equipment; d is the nominal diameter of the bolt; l a It is the basic anchoring length of the bolt.

9. The method for evaluating the installation strength of chemical bolts suitable for installing tunnel trackside equipment according to claim 8, characterized in that: In step 4, the pull-out bearing capacity of the chemical bolt is calculated as follows: (1) The pull-out bearing capacity of chemical bolts must first consider the tensile strength of the bolt material itself and is calculated according to formula (7); In the formula, F b is the pull-out bearing capacity of the bolt; d is the nominal diameter of the bolt; σ is the tensile strength of the bolt material; (2) The chemical bonding bearing capacity formed by the anchoring glue is calculated according to formula (8); F c =C×l d (8) In the formula, F c is the chemical bonding bearing capacity; C is the chemical anchoring coefficient; l d is the anchorage length of the bolt; (3) The locking force formed by the inverted cone tooth 1 is calculated according to formula (9); In the formula, F s is the locking force; c is the locking force coefficient, which is determined according to the grade and type of the bolt (first-grade bolt, c = 3.0, second-grade bolt c = 2.4); f cu h is the compressive strength of the base concrete cube; ef is the effective anchoring depth of the bolt; (4) Comprehensive bearing capacity: calculated according to formula (10). F=min(F b ,F c ,F s )(10)。 10. The installation strength evaluation method of chemical bolts suitable for tunnel trackside equipment installation according to claim 9, characterized in that: The step 5 is specifically as follows: Comparing the sizes of P and F, P and F should satisfy: P<βF (11) In the formula, β is the safety factor, β<1.

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