Eccentric wear failure judgment method for disc cutter chord of shield tunneling machine

Abstract

The invention discloses a shield tunneling machine disc cutter chord eccentric wear failure judgment method, which comprises the following steps: establishing a disc cutter stress prediction model, and calculating the rotating torque Tro of a disc cutter; based on the relevant parameters of the disc cutter and the rock, the total resistance moment Tre borne by the disc cutter in the rotating process is obtained; when the total resistance moment Tre borne by the disc cutter in the rotating process is larger than the rotating moment Tro of the disc cutter, the disc cutter cannot rotate, at the moment, the relative sliding coefficient xi in the contact area of the disc cutter and the rock is 1, the disc cutter is abraded under the relative sliding friction effect of the rock, and it is judged that the disc cutter chord eccentric wear failure occurs; otherwise, it is judged that the disc cutter chord eccentric wear failure does not occur. The method has the advantages that the total resistance moment Tre borne by the disc cutter in the rotating process and the rotating moment Tro of the disc cutter are calculated and compared, and therefore whether the disc cutter chord eccentric wear failure occurs or not is judged.

Description

Technical Field

[0001] The invention relates to the technical field of shield construction, in particular to a method for judging the failure of eccentric wear of a disc cutter string of a shield machine. Background Art

[0002] Shield machines are widely used in urban subway tunnel excavation projects due to their fast excavation speed, high safety and high degree of automation. The cutterhead system, as a key component of the shield machine tunneling, is mainly composed of disc cutters, scrapers, cutterhead bodies and slag chutes. When the shield machine is excavating, the disc cutters, as the main rock-breaking tool, penetrate and cut the rock under the thrust and torque of the cutterhead. The disc cutters perform three-dimensional spiral motion in space under the combined action of the cutterhead body and the rock. Therefore, the normal operation of the disc cutters is directly related to the excavation efficiency of the shield machine and also affects the construction cost.

[0003] The disc cutter structure is mainly composed of a cutter ring, a cutter body, an end cover, a cutter shaft and a sealing system. The outermost point of the disc cutter ring first contacts the fresh rock surface. As the cutter disc moves forward, the cutter part is embedded in the rock. At the same time, the cutter rolls the rock under the guidance of the rotation of the cutter disc until the outermost point is separated from the rock. At this point, the outermost point on the cutter completes the rock breaking task of one rotation of the cutter. As the cutter continues to rotate, each point on the cutter ring repeats the above action to complete the rock breaking. During the rock breaking process, the cutter is subjected to huge alternating loads, which can generally be divided into three-dimensional forces. Complex geological conditions such as soft soil sections, soft upper and hard lower strata, and high-strength and high-stress strata increase the frequency of cutter failures, and the performance of the cutter material directly affects the service life of the cutter.

[0004] Domestic and foreign scholars have studied the failure forms and causes of disc cutters. According to statistics of a large amount of engineering data, the failure forms of disc cutters are divided into normal wear and abnormal failure, among which the main abnormal failures are cutter ring breakage, eccentric wear of the cutter chord, and cutter ring edge curling. According to statistics of failed tools in actual construction, eccentric wear of the cutter chord is the most serious. The occurrence of eccentric wear of the cutter chord will sharply accelerate the wear of the other tools on the cutter disc. In the project, the cutters that are evenly worn but not worn much generally do not need to take tool replacement measures, or can continue to be used after changing their positions. On the contrary, eccentric wear of the cutter ring chord, which is not taken seriously due to its low probability of occurrence, can cause the entire cutter to fail once it occurs. If the tool that has experienced eccentric wear of the chord is not replaced in time, it is easy to cause damage to the tools of the entire cutter disc, endangering the safety of the equipment.

[0005] Therefore, a method for judging the eccentric wear failure of the disc cutter chord of a shield machine that can solve the above-mentioned problem is needed. Summary of the invention

[0006] The purpose of the present invention is to provide a method for judging the failure of the eccentric wear of the disc cutter of a shield machine according to the above-mentioned shortcomings of the prior art. re and the rotational torque T of the disc cutter ro And make a comparison to determine whether the disc cutter chordal wear failure occurs.

[0007] The purpose of the present invention is achieved by the following technical solutions:

[0008] A method for judging the failure of eccentric wear of disc cutter chord of a shield machine, the method comprising:

[0009] (S1) Establish a disc cutter force prediction model to calculate the disc cutter's torque T ro ;

[0010] (S2) Based on the relevant parameters of the disc cutter and the rock, the friction torque T of the disc cutter ring is calculated respectively. cq , the friction torque T of the disc cutter body ct and the starting torque T of the disc cutter during rock breaking st , the total resistance torque T of the disc cutter during rotation is obtained by accumulating re ;

[0011] (S3) The total resistance torque T when the disc cutter rotates re Greater than the rotational torque T of the disc cutter ro When , the disc cutter cannot rotate. At this time, the relative sliding coefficient ξ in the contact area between the disc cutter and the rock is 1. The disc cutter wears due to the relative sliding friction of the rock. It is judged that the chordal eccentric wear failure of the disc cutter occurs; otherwise, it is judged that the chordal eccentric wear failure of the disc cutter does not occur.

[0012] According to the disc cutter force prediction model, we get:

[0013]

[0014] In the formula, F t is the resultant force on the disc cutter; R is the radius of the disc cutter; ψ is the pressure distribution coefficient at the tip of the disc cutter, which decreases with the increase of the blade width, ψ = 0.2 ~ -0.2; θ is the angle between a point in the contact area and the center line of the disc cutter, θ = 0 ~ φ, φ is the contact angle between the disc cutter blade and the rock; C is a constant, with a value of 2.12; p is the pressure at any point in the crushing area, P 0 It is the pressure in the rock crushing area directly below the disc cutter, which is related to the rock strength, the shape of the disc cutter shaft, the penetration rate and the cutter spacing. 0 =f(σ t ,σ c,T,R,φ,S,h),σ c is the rock compressive strength, σ t is the tensile strength of rock, S is the cutter spacing of the disc cutter, T is the blade width of the disc cutter ring, and h is the penetration of the disc cutter; F n is the vertical force of the disc cutter breaking rock; F r It is the tangential force of the disc cutter breaking rock.

[0015] Rotational torque T of disc cutter ro The calculation formula is as follows:

[0016] T ro =F r R.

[0017] Friction torque T on the disc cutter ring cq The calculation formula is as follows:

[0018] T cq =μ 1 S cq p 1 R cq ;

[0019] In the formula, μ 1 is the friction coefficient between rock and soil and disc cutter; p 1 is the average pressure of rock and soil on the surface of the disc cutter ring, that is, the soil bin pressure; S cq R is the surface area of ​​the disc cutter ring in contact with the rock and soil; cq It is the average radius from the surface of the disc hob to the center of the cutter shaft;

[0020] Friction torque T on the disc cutter body ct The calculation formula is as follows:

[0021] T ct =μ 1 S ct p 1 R ct ;

[0022] In the formula, S ct R is the surface area of ​​the disc cutter body in contact with the rock and soil; ct It is the average radius from the surface of the disc hob body to the center of the cutter shaft;

[0023] Starting torque T of disc cutter in rock breaking process st It is the resistance torque generated between the internal structures when the disc cutter rotates, which is a constant value;

[0024] The total resistance torque T of the disc cutter during its rotation re The calculation formula is as follows:

[0025] Tre =T cq +T ct +T st .

[0026] The conditions for chordal wear of disc cutters are:

[0027] T ro <T re

[0028]

[0029] The calculation formula of the relative sliding coefficient ξ in the contact area between the disc cutter and the rock is as follows:

[0030]

[0031] Where, μ is the friction coefficient between the disc cutter and the rock; a is the contact half width of the disc cutter rolling the rock; E c is the elastic modulus of the disc cutter ring material; E r is the elastic modulus of rock material; c is the Poisson's ratio of the disc cutter ring material; r is the Poisson's ratio of rock material.

[0032] The invention has the advantages that: by calculating the total resistance moment T of the disc cutter during its rotation re and the rotational torque T of the disc cutter ro And make a comparison to determine whether the disc cutter chordal wear failure occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the contact between the disc cutter and the rock of the present invention;

[0034] Figure 2 It is a schematic diagram of the torque applied to the disc-shaped hob during the rotation process of the present invention;

[0035] Figure 3 This is a schematic diagram of the penetration data collection value of the shield machine of the present invention;

[0036] Figure 4 It is a schematic diagram of the critical penetration degree of the disc cutter under different geological conditions of the present invention for chordal eccentric wear;

[0037] Figure 5 It is a schematic diagram of the critical penetration degree of chordal wear of different geological disc cutters under different soil bin pressures of the present invention. DETAILED DESCRIPTION

[0038] The features of the present invention and other related features are further described in detail below through embodiments in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art:

[0039] Example: Figures 1 to 5 As shown, this embodiment relates to a method for judging the failure of eccentric wear of a disc cutter string of a shield machine, and the judgment method mainly includes:

[0040] (S1) Establish a disc cutter force prediction model to calculate the disc cutter's torque T ro .

[0041] Among them, Figure 1 As shown in the figure, according to the contact mechanics theory, when the disc cutter of the shield machine breaks rock, the disc cutter and the rock contact each other to produce elastic deformation. By analyzing the mapping relationship between friction and deformation, it can be concluded that there are micro-slip zones and adhesion zones in the contact area between the cutter and the rock, and the relative sliding coefficient ξ is introduced. The calculation formula of the relative sliding coefficient ξ in the contact area between the disc cutter and the rock is as follows:

[0042]

[0043] Where, μ is the friction coefficient between the disc cutter and the rock; a is the contact half width of the disc cutter rolling the rock; R is the radius of the disc cutter; F r is the tangential force of the disc cutter breaking rock; F n is the vertical force of the disc cutter breaking rock; E c is the elastic modulus of the disc cutter ring material; E r is the elastic modulus of rock material; c is the Poisson's ratio of the disc cutter ring material; r is the Poisson's ratio of rock material.

[0044] According to the disc cutter force prediction model, we get:

[0045]

[0046] In the formula, F t is the resultant force on the disc cutter; R is the radius of the disc cutter; ψ is the pressure distribution coefficient at the tip of the disc cutter, which decreases with the increase of the blade width, ψ = 0.2 ~ -0.2; θ is the angle between a point in the contact area and the center line of the disc cutter, θ = 0 ~ φ, φ is the contact angle between the disc cutter blade and the rock; C is a constant, with a value of 2.12; p is the pressure at any point in the crushing area, P 0 It is the pressure in the rock crushing area directly below the disc cutter, which is related to the rock strength, the shape of the disc cutter shaft, the penetration rate and the cutter spacing. 0 =f(σ t ,σ c ,T,R,φ,S,h),σ c is the rock compressive strength, σ tis the tensile strength of rock, S is the cutter spacing of the disc cutter, T is the blade width of the disc cutter ring, and h is the penetration of the disc cutter; F n is the vertical force of the disc cutter breaking rock; F r It is the tangential force of the disc cutter breaking rock.

[0047] Rotational torque T of disc cutter ro The calculation formula is as follows:

[0048] T ro =F r R.

[0049] (S2) Based on the relevant parameters of the disc cutter and the rock, the friction torque T of the disc cutter ring is calculated respectively. cq , the friction torque T of the disc cutter body ct and the starting torque T of the disc cutter during rock breaking st , the total resistance torque T of the disc cutter during rotation is accumulated re .

[0050] Among them, the friction torque T of the disc cutter ring is cq The calculation formula is as follows:

[0051] T cq =μ 1 S cq p 1 R cq ;

[0052] In the formula, μ 1 is the friction coefficient between rock and soil and disc cutter; p 1 is the average pressure of rock and soil on the surface of the disc cutter ring, that is, the soil bin pressure; S cq R is the surface area of ​​the disc cutter ring in contact with the rock and soil; cq It is the average radius from the surface of the disc hob to the center of the cutter shaft;

[0053] Friction torque T on the disc cutter body ct The calculation formula is as follows:

[0054] T ct =μ 1 S ct p 1 R ct ;

[0055] In the formula, S ct R is the surface area of ​​the disc cutter body in contact with the rock and soil; ct It is the average radius from the surface of the disc hob body to the center of the cutter shaft;

[0056] Starting torque T of disc cutter in rock breaking processst It is the resistance torque generated between the internal structures when the disc cutter rotates, mainly the friction torque of the bearing and the friction torque of the sealing system. The starting torque can be changed by adjusting the preload of the bearing. It is generally believed that the starting torque of the disc cutter during rock breaking is a constant value.

[0057] The total resistance torque T of the disc cutter during its rotation re The calculation formula is as follows:

[0058] T re =T cq +T ct +T st .

[0059] (S3) The total resistance torque T when the disc cutter rotates re Greater than the rotational torque T of the disc cutter ro When , the disc cutter cannot rotate. At this time, the relative sliding coefficient ξ in the contact area between the disc cutter and the rock is 1. The disc cutter wears due to the relative sliding friction of the rock. It is judged that the chordal eccentric wear failure of the disc cutter occurs; otherwise, it is judged that the chordal eccentric wear failure of the disc cutter does not occur.

[0060] Among them, Figure 2 As shown in the figure, the conditions for chordal wear of disc cutters are:

[0061] T ro <T re

[0062]

[0063] In this embodiment, before tunnel excavation, the shield machine and the cutter are generally selected based on the geological report along the tunnel. After the shield machine and the disc cutter are selected, the starting torque, the cutter spacing, and the cutter structure dimensions such as the disc cutter radius and the blade width remain unchanged. When tunneling, the excavation parameters need to be adjusted to cope with different strata, mainly by changing the penetration rate.

[0064] According to the geological report, the strata along the line are mainly composed of granite, clay layers and boulders. Due to the different degrees of differentiation of granite, the bedrock surface fluctuates greatly. At the same time, there are a large number of rock caves in the tunnel section, which are filled with yellow-brown clay, making the strata through which the tunnel line passes more complicated. The uniaxial compressive strength of the rock strata ranges from 20 to 75 MPa, with an average value of 47.5 MPa. The disc cutter structure dimensions used are as follows: cutter ring radius R = 241.3 mm; cutter ring blade width T = 20 mm; the surface area S of the disc cutter body in contact with the rock and soil ct =151325mm 2 ; The average radius R of the tool body from the tool axis center ct=148.5mm; the surface area of ​​the disc cutter ring in contact with the rock and soil S cq =259172mm 2 ; The average radius R of the cutter ring from the cutter axis center cq =191.6mm; blade spacing S = 82mm; starting torque T st =20N·m; soil bin pressure is 0.3MPa. Critical penetration value for chordal wear h cr =7.17mm.

[0065] Under the geological condition that the uniaxial compressive strength of the tunneling is 47.5Mpa, the shield machine penetration setting value must be greater than 7.12mm to avoid eccentric wear of the string. According to the actual tunneling data, the penetration value of the section where eccentric wear has occurred is preprocessed, and the start and stop phases of the shield machine and abnormal data are eliminated to obtain the shield machine penetration collection value in a certain construction interval, such as Figure 3 As shown. Figure 3 It can be seen that there are two locations where the penetration value is continuously below 7.12 mm, which indicates that the disc cutter has chordal wear in this construction area.

[0066] Considering that the geology is in a changing state during tunneling, the critical penetration of the disc cutter under different geological conditions for chordal wear can be obtained. Figure 4 It can be seen that with the increase of uniaxial compressive strength, the critical penetration of disc cutter for chordal wear decreases, and the reduction rate gradually tends to be gentle.

[0067] In order to avoid eccentric wear of a large number of disc cutters during tunnel excavation, in addition to the means of adjusting the penetration rate under different geological conditions, the soil bin pressure is changed to ensure the smooth excavation of the shield machine while ensuring the stability of the heading face. Therefore, the critical penetration value corresponding to different geological conditions under different soil bin pressure conditions can be calculated.

[0068] Depend on Figure 5 It can be seen that under the same geological conditions, the critical penetration of the shield machine disc cutter for chord eccentric wear increases with the increase of the soil bin pressure; with the increase of uniaxial compressive strength, the critical penetration increases with the increase of soil bin pressure and tends to be flat. Under the geological condition of uniaxial compressive strength of 47.5Mpa, when the soil bin pressure is reduced to 0.2Mpa, the critical penetration value is 4.47mm at this time. The penetration originally set in the range of 4.47-7.17mm will prevent the disc cutter from chord eccentric wear; if the slag in the soil bin is not discharged in time, as the slag in the soil bin accumulates, the soil bin pressure increases to 0.4Mpa, and the critical penetration value is 10.02mm at this time. The penetration originally set in the range of 7.17-10.02mm will put the cutter at risk of chord eccentric wear.

[0069] The beneficial technical effect of this embodiment is: by calculating the total resistance torque T of the disc cutter during its rotation process: re and the rotational torque T of the disc cutter ro And make a comparison to determine whether the disc cutter chordal wear failure occurs.

[0070] Although the above embodiments have described in detail the concepts and embodiments of the present invention with reference to the accompanying drawings, ordinary technicians in this field can recognize that various improvements and changes can still be made to the present invention without departing from the scope of the claims, so they are not described one by one here.

Claims

1. A method for judging the failure of eccentric wear of disc cutter chord of shield machine, characterized in that The determination method comprises: (S1) Establish a disc cutter force prediction model to calculate the disc cutter's torque T ro ; (S2) Based on the relevant parameters of the disc cutter and the rock, the friction torque T of the disc cutter ring is calculated respectively. cq , the friction torque T of the disc cutter body ct and the starting torque T of the disc cutter during rock breaking st , the total resistance torque T of the disc cutter during rotation is accumulated re ; (S3) The total resistance torque T when the disc cutter rotates re Greater than the rotational torque T of the disc cutter ro When , the disc cutter cannot rotate. At this time, the relative sliding coefficient ξ in the contact area between the disc cutter and the rock is 1. The disc cutter wears due to the relative sliding friction of the rock. It is judged that the chordal eccentric wear failure of the disc cutter occurs; otherwise, it is judged that the chordal eccentric wear failure of the disc cutter does not occur.

2. A method for judging the failure of shield machine disc cutter chord eccentric wear as claimed in claim 1, characterized in that According to the disc cutter force prediction model, we get: In the formula, F t is the resultant force on the disc cutter; R is the radius of the disc cutter; ψ is the pressure distribution coefficient at the tip of the disc cutter, which decreases with the increase of the blade width, ψ = 0.2 ~ -0.2; θ is the angle between a point in the contact area and the center line of the disc cutter, θ = 0 ~ φ, φ is the contact angle between the disc cutter blade and the rock; C is a constant, with a value of 2.12; p is the pressure at any point in the crushing area, P0 is the pressure in the rock crushing area directly below the disc cutter, which is related to the rock strength, the shape of the disc cutter shaft, the penetration and the distance between the cutters, P0 = f(σ t ,σ c ,T,R,φ,S,h),σ c is the rock compressive strength, σ t is the tensile strength of rock, S is the cutter spacing of the disc cutter, T is the blade width of the disc cutter ring, and h is the penetration of the disc cutter; F n is the vertical force of the disc cutter breaking rock; F r It is the tangential force of the disc cutter breaking rock.

3. A method for judging the failure of shield machine disc cutter chord eccentric wear as described in claim 2, characterized in that Rotational torque T of disc cutter ro The calculation formula is as follows: T ro =F r R。 4. A method for judging the failure of shield machine disc cutter chord eccentric wear as described in claim 3, characterized in that Friction torque T on the disc cutter ring cq The calculation formula is as follows: T cq =μ1S cq p1R cq ; Where μ1 is the friction coefficient between rock and soil and disc cutter; p1 is the average pressure of rock and soil on the surface of disc cutter ring, i.e. soil bin pressure; S cq R is the surface area of ​​the disc cutter ring in contact with the rock and soil; cq It is the average radius from the surface of the disc hob to the center of the cutter shaft; Friction torque T on the disc cutter body ct The calculation formula is as follows: T ct =μ1S ct p1R ct ; In the formula, S ct R is the surface area of ​​the disc cutter body in contact with the rock and soil; ct It is the average radius from the surface of the disc hob body to the center of the cutter shaft; Starting torque T of disc cutter in rock breaking process st It is the resistance torque generated between the internal structures when the disc cutter rotates, which is a constant value; The total resistance torque T of the disc cutter during its rotation re The calculation formula is as follows: T re =T cq +T ct +T st 。 5. A method for judging the failure of shield machine disc cutter chord eccentric wear as claimed in claim 4, characterized in that The conditions for chordal wear of disc cutters are: T ro <T re 6. A method for judging the failure of shield machine disc cutter chord eccentric wear as claimed in claim 2, characterized in that The calculation formula of the relative sliding coefficient ξ in the contact area between the disc cutter and the rock is as follows: Where, μ is the friction coefficient between the disc cutter and the rock; a is the contact half width of the disc cutter rolling the rock; E c is the elastic modulus of the disc cutter ring material; E r is the elastic modulus of rock material; c is the Poisson's ratio of the disc cutter ring material; r is the Poisson's ratio of rock material.

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