Bolt sleeve structure for shield tunnel segment connection

Abstract

The invention provides a bolt sleeve structure for shield tunnel segment connection, and relates to the technical field of tunnel and underground engineering, a bolt sleeve adopts a trapezoidal internal thread, the height of the trapezoid is 1 / 4 of the thread pitch, the width of an inner concave trapezoid in the pitch diameter is marked as wa, the width of an outer convex trapezoid in the pitch diameter is marked as wt, and the thread pitch is 1 / 4; the lead angle is smaller than or equal to the equivalent friction angle; the total length L of the bolt sleeve is greater than or equal to zeta mp; wherein zeta is the reserve coefficient, m is the thread number of the bolt sleeve, and p is the thread pitch; m is greater than or equal to 10 / w4, 10 is the sheared length, and w4 is the width of the bottom surface of the convex trapezoid; 10 is larger than or equal to F / (sigma t pi D), F is the maximum allowable tension of the bolt, sigma t is the shearing strength of the bolt sleeve, and D is the nominal diameter of the bolt. According to the invention, the allowable installation error of the bolt and the bolt sleeve is improved, the screw thread of the bolt sleeve is prevented from being extruded and cut up when the bolt is screwed, and the anti-pulling capability of the bolt is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel and underground engineering, and particularly relates to a bolt sleeve structure for shield tunnel segment connection. BACKGROUND

[0002] The bolt sleeve for segment connection of the existing shield tunnel is mostly made of polyamide material and has a circular arc thread structure; for example, a commonly used M30 bolt sleeve has a pitch p = 5-6 mm and a middle diameter 24.2 mm (as shown in FIG. 1). Figure 1 With the same bolt length, the smaller the pitch is, the more the number of threads is. However, the materials of the steel bolt and the plastic bolt sleeve are different, and the manufacturing precisions are different. Due to the large number of threads, the errors are easily accumulated, and the material strengths of the two are greatly different. Therefore, the thread roots of the plastic bolt sleeve are often extruded and cut when the steel bolt is tightened, so that the bolt pull-out resistance is low and the designed tensile strength of the steel bolt cannot be reached, and the connection reliability is insufficient.

[0003] The specification GB / T 5796 “trapezoidal thread” provides a trapezoidal thread profile, and the basic thread profile stipulates that the thread height H2 is equal to 0.5 times the pitch, that is, the thread root of the internal thread is deep, and the thread top width is the same as the thread root width. This thread profile also easily causes the thread roots of the plastic bolt sleeve to be extruded and cut when the steel bolt is tightened, so that the bolt pull-out resistance is low and the designed tensile strength of the steel bolt cannot be reached. SUMMARY

[0004] The present application aims to provide a bolt sleeve structure for shield tunnel segment connection, which aims to increase the allowable installation error between the bolt and the bolt sleeve thread, make the bolt and the bolt sleeve tightly engage, and improve the fastening capacity of the bolt, so as to solve the problem that the allowable error of the existing bolt and the bolt sleeve is small, and the polyamide bolt sleeve is easily extruded and cut when the steel bolt is tightened. The specific technical scheme is as follows:

[0005] A bolt sleeve structure for shield tunnel segment connection, the bolt sleeve adopts a trapezoidal internal thread, the trapezoidal height of the trapezoidal internal thread is 1 / 4 of the pitch, the width of the internal thread concave trapezoid at the middle diameter D2 position is denoted as w a , and the width of the internal thread convex trapezoid at the middle diameter D2 position is denoted as w t , wherein, the pitch is p; the thread angle is less than or equal to the equivalent friction angle; the thread angle is less than or equal to the equivalent friction angle; the total length L of the bolt sleeve satisfies: L≥ζmp; wherein, ζ is a reserve coefficient, m is the number of bolt sleeve threads, and p is the pitch; m≥l0 / w4, l0 is the shear length, and w4 is the bottom width of the convex trapezoid of the trapezoidal internal thread; F is the maximum allowable pull of the bolt, and σ t is the shear strength of the bolt sleeve, and D is the nominal diameter of the bolt.

[0006] Furthermore, all four corners of the trapezoidal internal thread are chamfered.

[0007] Furthermore, the trapezoidal internal thread adopts a single thread structure.

[0008] Furthermore, the width of the concave trapezoidal internal thread at the position of the mean diameter D2 is denoted as w. a The width of the externally convex trapezoidal internal thread at the position of the mean diameter D2 is denoted as w. t w a <w t .

[0009] Furthermore, the bolt sleeve is made of polyamide material.

[0010] The bolt sleeve structure for connecting shield tunnel segments provided by this invention has the following beneficial effects:

[0011] The bolt sleeve structure for connecting shield tunnel segments of the present invention improves the allowable installation error between the bolt and the bolt sleeve by setting the trapezoidal thread profile of the bolt sleeve and the total length of the bolt sleeve, avoids the situation where the bolt sleeve thread is squeezed and cut when the bolt is tightened, and improves the pull-out resistance of the bolt. Attached Figure Description

[0012] Figure 1 This is a construction diagram of a bolt sleeve with an arc-shaped thread, based on existing technology.

[0013] Figure 2 This is a structural diagram of the inner side of the nut provided by the present invention.

[0014] Figure 3 This is a detailed drawing of the inner structure of the nut provided by the present invention.

[0015] Figure 4 The diagram shows the construction of the M36 matching nut provided by this invention. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0017] This invention provides a bolt sleeve structure for connecting shield tunnel segments, see reference. Figure 2 , 3As shown, the bolt sleeve uses a trapezoidal internal thread. In a preferred embodiment, all four corners of the trapezoid are chamfered, r=0.5mm. The number of thread lines is denoted as n. In a preferred embodiment, n=1, i.e., a single thread structure is used; a double thread structure can also be used. The pitch is p, the nominal diameter of the bolt is D, the pitch diameter of the internal thread is D2, and the minor diameter of the internal thread is D1. The height of the trapezoid is denoted as h. In this embodiment, it is taken as 1 / 4 of the pitch, i.e., h=p / 4. According to the diameter relationship, D2=Dh, D1=D-2h. The thread profile angle is denoted as β, which is the angle between the side of the thread tooth and the plane perpendicular to the thread axis, generally half of the thread profile angle. The width of the concave trapezoidal internal thread at the position of the pitch diameter D2 is denoted as w. a The width of the externally convex trapezoidal internal thread at the position of the mean diameter D2 is denoted as w. t Then the width of the concave trapezoid's base w1 = w a +htanβ, width of the concave trapezoidal top surface w2=w a -htanβ, the width of the convex trapezoidal top surface w3=w t -htanβ, the width of the convex trapezoidal base is w4=w t +htanβ, and has To make bolt installation easier, w is used. a Less than w t .

[0018] This invention provides a method for calculating thread self-locking conditions and adjusting the thread profile or the static friction coefficient between the bolt and bolt sleeve based on whether self-locking is present.

[0019] The static friction coefficient between the bolt and the bolt sleeve is denoted as f, and the thread helix angle is... The equivalent friction angle ρ' = fcosβ. When the thread helix angle is less than or equal to the equivalent friction angle (ψ≤ρ'), the bolt can self-lock; when the thread helix angle is greater than the equivalent friction angle (ψ>ρ'), the bolt cannot self-lock. If the bolt cannot self-lock, the thread profile bevel angle can be adjusted, or the static friction coefficient of the bolt pair can be increased.

[0020] The present invention also provides the following method for determining the length of the bolt sleeve: the shear strength of the bolt sleeve is denoted as σ. t The maximum allowable tensile force of a bolt is denoted as F, which is obtained through a bolt pull-out test, or through the bolt's ultimate tensile strength σ and stress cross-sectional area A. s The calculation yields F = σA s The length L of the bolt sleeve should include sufficient shear length so that the bolt sleeve does not suffer shear failure when the bolt breaks. Let the shear length be denoted as l0, and the reserve coefficient be denoted as ζ. Then, σ... t πDl0≥F, that is Therefore, we can obtain that the number of threads on the bolt sleeve m≥l0 / w4, and the total length of the bolt sleeve L≥ζmp.

[0021] The present invention will now be described in further detail with reference to preferred embodiments.

[0022] When using M36 bolts, the calculation process for each dimension is as follows: Given D=36mm, p=12mm, h=3mm, β=15°, then D1=D-2h=30mm, w t =0.5208p=6.25mm, w1=w a +htanβ=7.05mm, w2=w a -htanβ=5.45mm, w3=p-w1=4.95mm, w4=p-w2=7.55mm.

[0023] Determine if the bolt is self-locking:

[0024] The thread helix angle Ψ = atan(12 / 30π) = 7.26°. The coefficient of friction between steel and polyamide material under no lubrication is f≈0.3. Therefore, the equivalent friction angle ρ' = 0.3cos15° = 0.311 = 16.16°. Thus, Ψ < ρ', and the bolt can self-lock.

[0025] Calculate the bolt sleeve length:

[0026] The bolt sleeve is made of polyamide material with a shear strength of 50MPa. The maximum allowable tensile force of the bolt is 678kN. Therefore, l0 = 678 / 50 / (36π) = 119.88mm, m = 15.88, so L ≥ 1.15 × 15.88 × 12 = 219mm. We take L = 220mm.

[0027] The structural dimensions of the bolt sleeve are thus obtained as follows: Figure 4 As shown.

[0028] Those skilled in the art should understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the invention. Any changes or modifications made by those skilled in the art based on the embodiments of the present invention and the above disclosure shall fall within the protection scope of the claims.

Claims

1. A bolt sleeve structure for connecting shield tunnel segments, characterized in that, The bolt sleeve uses a trapezoidal internal thread. The height of the trapezoidal internal thread is 1 / 4 of the thread pitch. The width of the concave trapezoidal internal thread at the position of the pitch diameter D2 is denoted as w. a The width of the externally convex trapezoidal internal thread at the position of the mean diameter D2 is denoted as w. t ,have ,in, The thread pitch is given; the thread helix angle is less than or equal to the equivalent friction angle; the total length L of the bolt sleeve satisfies: L≥ζmp; where ζ is the reserve coefficient, m is the number of threads on the bolt sleeve, and p is the thread pitch; m≥l0 / w4, where l0 is the shear length and w4 is the width of the outer convex trapezoidal base of the trapezoidal internal thread; F is the maximum allowable tensile force of the bolt, σ t Where D is the shear strength of the bolt sleeve, and D is the nominal diameter of the bolt.

2. The bolt sleeve structure for connecting shield tunnel segments according to claim 1, characterized in that, All four corners of the trapezoidal internal thread are chamfered.

3. The bolt sleeve structure for connecting shield tunnel segments according to claim 1, characterized in that, The trapezoidal internal thread adopts a single thread structure.

4. The bolt sleeve structure for connecting shield tunnel segments according to claim 1, characterized in that, In a <w t 。 5. The bolt sleeve structure for connecting shield tunnel segments according to claim 2, characterized in that, The bolt sleeve is made of polyamide material.

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