Shield cutting line launching method

Abstract

The application discloses a shield cutting line launching method, which is characterized in that numerical control jacks and counterforce frames are respectively arranged on two sides of a launching bracket, when it is needed to adjust the launching posture of the shield to one side, the numerical control jack on the side only plays a supporting role, and the launching posture is adjusted by controlling the numerical control jack on the other side to generate a thrust force, so that the launching posture of the shield can be adjusted after the shield body is hoisted, and the center line of the shield machine can be kept in the line design curve cutting line direction excavation. Moreover, when the launching posture is adjusted, whether the launching posture meets the design requirement can be preliminarily estimated, the shield design parameter can be adjusted in time when the launching posture does not meet the design requirement, the shield posture parameter is calculated based on the shield design parameter, and the thrust force values of the numerical control jacks are calculated based on the shield posture parameter. The application firstly proposes a calculation model for calculating the thrust force values of the numerical control jacks based on the shield design parameter, and the calculation model can be well applied to the posture adjustment in the shield cutting line launching stage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of shield construction, in particular, to a shield cutting line launching method. BACKGROUND

[0002] In the curve shield launching stage, the shield machine center line keeps excavating in the tangent direction of the line design curve, which is called tangent launching. The advantage of the tangent launching technology is that the shield machine launching base axis and the portal plane keep a vertical relationship, and the shield machine body and the portal steel ring keep a balanced spatial position relationship during the launching process. However, when the shield machine drives out of the reinforced position, the cutter head cutting center deviates too much from the line design axis, which is not conducive to the shield posture adjustment and the pipe piece assembly quality control. In the small radius curve launching process, the tunnel pipe piece will be offset along the outside of the tunnel axis under the lateral pressure, thereby causing the shield machine posture to exceed the limit and other problems. In order to avoid such problems and reduce the mutual influence between the shield machine and the pipe piece, a pre-offset can be set at the shield tail relative to the design axis, so that the shield and the launching portal keep a certain angle of deflection for launching operation. Specifically, the rear end of the launching bracket is offset a certain distance along the normal line of the line design curve in the opposite direction of the curve, so that the shield machine center line keeps excavating in the cutting line direction of the line design curve, which is called cutting line launching. Therefore, before the shield machine cutting line launching, the shield tail pre-offset and the pre-angle of deflection need to be designed according to the line design curve and the shield size, and then the launching bracket is installed according to the designed pre-offset and pre-angle of deflection, and then the shield body is installed on the launching bracket. However, if it is found that the pre-set offset and angle do not meet the requirements when the shield starts to launch, it is very difficult and complex to adjust the posture of the shield body and the launching bracket at this time, which will increase the construction cost and delay the construction progress. SUMMARY

[0003] The present application provides a shield cutting line launching method to solve the technical problem that the existing cutting line launching method is difficult to adjust the shield posture after the launching bracket and the shield body are installed.

[0004] According to one aspect of the present application, a shield cutting line launching method is provided, which includes the following contents:

[0005] The launching bracket is installed, and a plurality of numerical control jacks and reaction frames are installed on both sides of the launching bracket;

[0006] The shield body is hoisted to the launching bracket;

[0007] The shield guide control system is installed and connected with the numerical control jacks, and the launching posture is adjusted by controlling the thrust of the plurality of numerical control jacks;

[0008] The propelling reaction frame is installed behind the launching bracket;

[0009] The portal is broken;

[0010] Manually check whether the shield posture is consistent with the starting posture;

[0011] Install negative ring segments;

[0012] Seal the cave entrance;

[0013] During shield tunneling, when the shield body completely enters the soil, the assembly of the ten ring segments is completed and the start is completed.

[0014] Furthermore, the process of controlling the thrust of the plurality of CNC jacks to adjust the starting posture is specifically as follows:

[0015] The maximum offset between the starting axis of the shield cutting line and the line design axis is estimated based on the shield design parameters, and it is judged whether the maximum offset meets the design requirements. If it does not meet the design requirements, the shield design parameters are adjusted;

[0016] The shield attitude parameters are calculated based on the adjusted shield design parameters;

[0017] The thrust value of each CNC jack is calculated based on the shield posture parameters.

[0018] Furthermore, the maximum offset between the starting axis of the shield cutting line and the line design axis is estimated based on the following formula:

[0019]

[0020] Among them, δ represents the maximum offset, R represents the line design curve radius, and L represents the shield length. When δ is less than or equal to 50 mm, it is determined that the maximum offset meets the design requirements. When δ is greater than 50 mm, it is determined that the maximum offset does not meet the design requirements. By adjusting the shield design parameters R and L, δ is made less than or equal to 50 mm.

[0021] Furthermore, when the shield design parameters can no longer be adjusted, the maximum offset between the shield secant starting axis and the line design axis is estimated based on the following formula:

[0022]

[0023] Where D is the shield diameter, Δ is the shield tail offset, When δ is less than or equal to 50 mm, the maximum offset is determined to meet the design requirements. When δ is greater than 50 mm, the maximum offset is determined to not meet the design requirements. The shield design parameters R and L are adjusted to make δ less than or equal to 50 mm.

[0024] Furthermore, the process of calculating the thrust value of each CNC jack based on the shield posture parameters includes the following:

[0025] A working space coordinate system for adjusting the posture of the shield is established with the center point of the cutter head as the origin, the tangent direction of the design axis of the line as the x-axis direction, the direction of the section along the axis of the shield and perpendicular to the design axis of the line as the y-axis direction, and the z-axis direction determined in combination with the right-hand rule;

[0026] A conversion matrix from the working space coordinate system to the pushing direction is constructed based on the pre-offset angle, and a matrix of the installation mode of the numerical control jacks is constructed;

[0027] The elongation vector of each numerical control jack is obtained based on the geometric relationship, the conversion matrix and the matrix of the installation mode of the numerical control jacks;

[0028] The elongation of each numerical control jack is calculated based on the elongation vector of each numerical control jack, the diameter of the shield and the tail offset, and the pushing force value of each numerical control jack is calculated.

[0029] Further, the conversion matrix is The matrix of the installation mode of the numerical control jacks is Wherein, n represents the number of numerical control jacks generating pushing force, θ represents the pre-offset angle, and D represents the diameter of the shield.

[0030] Further, the elongation vector of the i-th jack is r = [x y z] T + χQ-Q, wherein x, y and z represent the relative coordinate transformation amount of the tail edge point relative to the working space coordinate system, and the coordinate transformation can be obtained through the geometric relationship and the conversion matrix x A , y A , and z A respectively represent the absolute coordinate amount of the tail edge point in the working space coordinate system, so that the elongation vector of the i-th numerical control jack can be obtained as:

[0031]

[0032] Wherein, L represents the length of the shield, and Δ represents the tail offset.

[0033] Further, the elongation of the i-th numerical control jack is calculated based on the following formula:

[0034] l i = rτ i -(D+Δ)

[0035] Wherein, l i represents the elongation of the i-th numerical control jack, τ i represents the unit directional vector of the elongation vector of the i-th numerical control jack along the pushing direction,

[0036] Further, after calculating the thrust value of each numerical control jack, the following contents are included:

[0037] Judge whether the thrust generated by the plurality of numerical control jacks satisfies the dynamic equation and the shield rotation differential equation.

[0038] Further, the dynamic equation is:

[0039]

[0040] Wherein, P i represents the thrust of the i-th numerical control jack, n represents the number of numerical control jacks generating thrust, e yA represents the vector of the shield in the y-axis direction of the working space coordinate system, f represents the resistance received by the shield, m represents the total mass of the shield and the starting carrier, v represents the velocity, and t represents the time;

[0041] The shield rotation differential equation is:

[0042]

[0043] Wherein, e zA represents the vector of the shield in the z-axis direction of the working space coordinate system, χ represents the conversion matrix, Q represents the numerical control jack installation mode matrix, M f represents the constraint torque received by the shield, J represents the moment of inertia of the shield around its rotation center, ω represents the angular velocity, L represents the length of the shield, λ represents the resistance coefficient, and a represents the distance between adjacent numerical control jacks.

[0044] The present application has the following effects:

[0045] The shield line starting method of the present application installs numerical control jacks and counterforce frames on both sides of the starting carrier, controls the thrust of the plurality of numerical control jacks through the shield guide control system, and when it is necessary to adjust the shield starting posture to which side, the numerical control jacks on that side only serve as support, and the numerical control jacks on the other side generate thrust to push the starting carrier and the shield to adjust the starting posture, thereby facilitating the adjustment of the shield starting posture after the shield is hoisted, to ensure that the center line of the shield machine remains on the line design curve tangent line direction excavation, and completes the tangent line starting. Moreover, when adjusting the starting posture, it can be preliminarily estimated whether the starting posture meets the design requirements, and when the design requirements are not met, the shield design parameters can be adjusted in time, and the shield posture parameters are calculated based on the shield design parameters, and the thrust values of the plurality of numerical control jacks generating thrust are calculated based on the shield posture parameters. The present application first proposes a calculation model for calculating the thrust value of the numerical control jack based on the shield design parameters, which can be well applied to the posture adjustment in the shield tangent line starting stage.

[0046] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0048] Figure 1 It is a flow chart of a shield cutting line initiation method according to a preferred embodiment of the present invention.

[0049] Figure 2 It is a schematic diagram of installing CNC jacks on both sides of the starting bracket in a preferred embodiment of the present invention.

[0050] Figure 3 It is a schematic diagram of hoisting the shield onto the starting bracket in a preferred embodiment of the present invention.

[0051] Figure 4 yes Figure 1 Schematic diagram of the sub-process of step S3 in FIG.

[0052] Figure 5 It is a schematic diagram of the geometric relationship between multiple shield design parameters when the shield cutting line is initiated in the preferred embodiment of the present invention.

[0053] Figure 6 yes Figure 4 Schematic diagram of the sub-process of step S33.

[0054] Figure 7 It is a schematic diagram of the working space coordinate system for shield posture adjustment in a preferred embodiment of the present invention.

[0055] Figure 8 It is a schematic diagram of the working space coordinate system for shield posture adjustment at another angle in a preferred embodiment of the present invention.

[0056] Figure 9 yes Figure 4 Another sub-process diagram of step S33 in FIG. DETAILED DESCRIPTION

[0057] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0058] like Figure 1 As shown, a preferred embodiment of the present invention provides a shield cutting line initiation method, comprising the following contents:

[0059] Step S1: Installing a starting bracket, and installing multiple CNC jacks and reaction frames on both sides of the starting bracket;

[0060] Step S2: hoisting the shield onto the starting bracket;

[0061] Step S3: Install the shield guidance control system and connect it to the CNC jacks, and adjust the starting posture by controlling the thrust of multiple CNC jacks;

[0062] Step S4: Installing a propulsion reaction frame behind the starting bracket;

[0063] Step S5: breaking the cave door;

[0064] Step S6: Manually check whether the shield posture is consistent with the starting posture;

[0065] Step S7: installing the negative ring segment;

[0066] Step S8: sealing the tunnel door;

[0067] Step S9: Shield tunneling. When the shield body completely enters the soil, the assembly of the ten ring segments is completed and the start is completed.

[0068] It can be understood that the shield tunneling line starting method of this embodiment installs CNC jacks and reaction frames on both sides of the starting bracket, and controls the thrust of multiple CNC jacks through the shield guidance control system. When the shield tunneling line needs to be adjusted to a certain side, the CNC jack on that side only serves as a support, while the CNC jack on the other side is controlled to generate thrust to push the starting bracket and shield body to adjust the starting posture. This facilitates the adjustment of the shield tunneling line starting posture after the shield body is hoisted, ensuring that the centerline of the shield machine remains in the direction of the secant line of the designed route curve during excavation, completing the secant line starting. Moreover, when adjusting the starting posture, a preliminary estimate can be obtained to determine whether the starting posture meets the design requirements. If it does not meet the design requirements, the shield design parameters can be adjusted in a timely manner, and the shield posture parameters can be calculated based on the shield design parameters. The thrust values ​​of the multiple CNC jacks that generate thrust are then calculated based on the shield posture parameters. This present invention proposes for the first time a calculation model for calculating the thrust values ​​of the CNC jacks based on the shield design parameters, which is well suited for posture adjustment during the shield tunneling line starting stage.

[0069] It can be understood that in step S1, the starting bracket is first installed, and a guide rail is set between the starting bracket and the portal steel ring to prevent the shield from "knocking" when starting. Figure 2 As shown, multiple CNC jacks are evenly installed on both sides of the starting bracket to facilitate adjustment of the posture of the starting bracket.

[0070] It can be understood that in step S2, if Figure 3As shown, the shield body is hoisted onto the starting bracket in the order of shield tail, middle shield, front shield and cutter disc.

[0071] It can be understood that in step S3, the shield guidance control system is installed and debugged, and then the CNC jacks are connected to the shield guidance control system, and the thrust value of each CNC jack is controlled by the shield guidance control system. Figure 4 As shown, the process of controlling the thrust adjustment starting posture of multiple CNC jacks is specifically as follows:

[0072] Step S31: estimating the maximum offset between the starting axis of the shield cutting line and the line design axis based on the shield design parameters, and determining whether the maximum offset meets the design requirements. If not, adjusting the shield design parameters;

[0073] Step S32: Calculating shield attitude parameters based on the adjusted shield design parameters;

[0074] Step S33: Calculate the thrust value of each CNC jack based on the shield posture parameters.

[0075] Specifically, if Figure 5 As shown in the figure, in the actual construction process, the distance between the front end of the shield and the tunnel portal is very small, or even close to each other. Therefore, according to the geometric transformation relationship, the following relationship can be obtained:

[0076]

[0077] Among them, θ represents the pre-deflection angle, L represents the shield body length, R represents the line design curve radius, Δ represents the shield tail offset, δ represents the maximum offset between the shield secant starting axis and the line design axis, α represents the central angle of the shield body corresponding to the starting point of the shield secant line of the curved segment, the shield design parameters include the shield body length L and the line design curve radius R, and the shield posture parameters include the pre-deflection angle θ and the shield tail offset Δ.

[0078] Therefore, the maximum offset between the starting axis of the shield cutting line and the design axis of the line can be estimated based on the following formula:

[0079]

[0080] When δ is less than or equal to 50mm, it is determined that the maximum offset meets the design requirements. When δ is greater than 50mm, it is determined that the maximum offset does not meet the design requirements. By adjusting the shield design parameters R and L, δ is made less than or equal to 50mm. Generally, δ is made less than or equal to 50mm by reducing R or L.

[0081] When the shield length L and / or the line design curve radius R are adjusted so that δ is less than or equal to 50 mm, the shield posture parameters are calculated based on the above formula using the adjusted shield length L and the line design curve radius R, and then the thrust value of each CNC jack is calculated based on the calculated shield posture parameters.

[0082] Alternatively, due to the limited space in the shield launch shaft, when the shield design parameters cannot be adjusted, for example, when the line design curve radius R is too small and cannot be adjusted, the shield body diameter D is introduced into the shield design parameters. Based on the geometric transformation relationship, the following relationship can be obtained:

[0083]

[0084] Therefore, the maximum offset between the starting axis of the shield cutting line and the design axis of the line can be estimated based on the following formula:

[0085]

[0086] Among them, when δ is less than or equal to 50mm, it is determined that the maximum offset meets the design requirements. When δ is greater than 50mm, it is determined that the maximum offset does not meet the design requirements. By adjusting the shield design parameters R and L, δ is made less than or equal to 50mm. The shield attitude parameters are then calculated based on the above formula using the adjusted shield length L and the line design curve radius R. The thrust value of each CNC jack is then calculated based on the calculated shield attitude parameters. Generally speaking, due to the limited space in the shield starting shaft, the line design curve radius R is too small to be adjusted further, and the shield diameter D is generally a set value. Therefore, δ is made less than or equal to 50mm by reducing the shield length L.

[0087] Among them, Figure 6 As shown, the process of calculating the thrust value of each CNC jack based on the shield posture parameters includes the following:

[0088] Step S331: Establish a workspace coordinate system for shield posture adjustment, with the cutterhead center point as the origin, the tangent direction of the line design axis as the x-axis direction, the direction of the section along the shield axis and perpendicular to the line design axis as the y-axis direction, and the z-axis direction determined in combination with right-hand positioning;

[0089] Step S332: constructing a transformation matrix from the workspace coordinate system to the pushing direction based on the pre-bias angle, and constructing a CNC jack installation mode matrix;

[0090] Step S333: obtaining the elongation vector of each CNC jack based on the geometric relationship, the transformation matrix, and the CNC jack installation mode matrix;

[0091] Step S334: Calculate the elongation of each CNC jack based on the elongation vector of each CNC jack, the shield diameter, and the shield tail offset, and then calculate the thrust value of each CNC jack.

[0092] Specifically, if Figure 7 and Figure 8 As shown, the center of the cutter head O c The origin, the tangent direction of the line design axis is the x-axis direction, the direction along the shield axis and perpendicular to the line design axis is the y-axis direction, and the z-axis direction is determined by combining the right-hand positioning to establish the working space coordinate system A for shield posture adjustment. Then, based on the pre-deflection angle, the transformation matrix from the working space coordinate system to the pushing direction is constructed. At the same time, the number of CNC jacks is an even number and is expressed in X. A The axial symmetry is evenly distributed in the installation direction, and the working plane can be regarded as a concentric circle with the origin of the coordinate system A as the center, so the CNC jack installation matrix is ​​constructed as follows: Where n represents the number of CNC jacks that generate thrust, θ represents the pre-deflection angle, and D represents the shield diameter.

[0093] In the initial attitude adjustment process, assuming that the elongation vector of the i-th CNC jack is r, the elongation l of the i-th CNC jack can be obtained according to the geometric relationship. i The relationship between it and the elongation vector r is: Therefore, l i =rτ i -(D+Δ),τ i Represents the unit direction vector of the extension vector r of the i-th CNC jack along the pushing direction, The extension vector of the i-th jack can be expressed as r = [xyz] T +χQ-Q, where x, y, and z represent the relative coordinate transformation of the shield tail edge point relative to the workspace coordinate system. The coordinate transformation can be obtained by geometric relationship and transformation matrix. x A 、y A 、z A represent the absolute coordinates of the shield tail edge point in the workspace coordinate system, and Therefore, the extension vector of the i-th CNC jack can be obtained as:

[0094] Thus, the elongation l of the i-th CNC jack can be calculated i .

[0095] For each CNC jack, the thrust value can be calculated based on the following formula:

[0096] P i =Kli

[0097] Among them, P i It represents the thrust value of the i-th CNC jack, and K represents the stiffness coefficient, which is only related to the CNC jack itself.

[0098] It is understood that in another embodiment of the present invention, Figure 9 As shown, after calculating the thrust value of each CNC jack, the following contents are also included:

[0099] Step S335: Determine whether the thrust generated by the multiple CNC jacks satisfies the dynamic equation and the shield rotation differential equation. The dynamic equation is:

[0100]

[0101] Among them, P i represents the thrust of the i-th CNC jack, n represents the number of CNC jacks that generate thrust, e yA represents the vector of the shield in the y-axis direction of the workspace coordinate system, f represents the resistance of the shield, m represents the total mass of the shield and the starting bracket, v represents the speed, and t represents the time. The shield rotation differential equation is:

[0102]

[0103] Among them, e zA represents the vector of the shield in the z-axis direction of the workspace coordinate system, χ represents the transformation matrix, Q represents the CNC jack installation matrix, M f represents the restraining torque applied to the shield, J represents the shield's moment of inertia about its center of rotation, ω represents the angular velocity, L represents the shield's length, λ represents the drag coefficient, and a represents the distance between adjacent CNC jacks. If the above dynamic equations and the shield's rotational differential equation are satisfied, the thrust applied by the CNC jacks can propel the shield and launch bracket to adjust their posture. If these conditions are not met, the shield design parameters must be readjusted and the thrust value recalculated.

[0104] It will be appreciated that in step S4, the thrust reaction frame is made of steel, and the strength of the steel must be sufficient to provide sufficient thrust for shield tunneling. Furthermore, since the thrust reaction frame is perpendicular to the starting secant line, it will also form a corresponding angle with the station side wall. The thrust reaction frame support is not perpendicular to the station side wall. During the initial thrust, the shield will exert a lateral force on the thrust reaction frame, which can easily cause the thrust reaction frame to deform or tilt. Therefore, the present invention also adds support to the side of the thrust reaction frame to increase the stability and safety of the thrust reaction frame when the secant line is initiated.

[0105] It can be understood that in step S5, the portal plane must be parallel to the cutterhead plane when the portal is broken to prevent uneven reaction force on the shield machine, which may cause lateral displacement of the shield machine, the starting bracket, and the thrust reaction frame, thereby causing the starting direction of the cutting line to change.

[0106] It can be understood that in step S6, after the tunnel portal is broken, it is necessary to manually re-measure whether the shield posture is consistent with the initial posture. If it is consistent, the next step can be carried out; if it is inconsistent, measure whether the difference is too large. If the difference is too large to adjust, it can only be dismantled and reinstalled. If the difference is not large, the shield guidance control system can continue to be used to make small adjustments to the posture.

[0107] It is understood that in step S7, the negative ring segments should be assembled in a complete ring. The assembled negative ring should be promptly reinforced with wire ropes, with the bottom of the wire ropes connected to the starting frame. This not only increases the stability of the negative ring segments but also ensures their positive roundness. In addition, the negative ring segments are bolted to the reference ring of the thrust and reaction frame. The bolts between the negative rings should be promptly tightened to prevent displacement of the negative ring segments, which could affect the quality of subsequent segment assembly or create safety hazards.

[0108] It can be understood that in step S8, the removed hole door must be sealed in time to prevent the occurrence of block falling, water gushing, etc.

[0109] It can be understood that in step S9, when the shield body completely enters the soil, the direction of shield excavation is controlled to approach the designed curve, and ten ring segments are assembled to provide sufficient thrust for shield excavation. At this time, the thrust reaction frame and the starting bracket can be removed, and the shield cutting line is started.

[0110] It can be understood that the shield cutting line starting method of the present invention controls and adjusts the starting bracket through calculation, and then adjusts the starting posture of the shield machine, solving the problem of difficulty in adjusting the posture of the shield body on the starting bracket. At the same time, the cutting line starting method is adopted to make the shield machine move along the requirements close to the design curve, thereby improving the accuracy and efficiency of shield excavation construction. At the same time, the present invention is suitable for most shield cutting line starting and has high universal applicability.

[0111] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A shield cutting line starting method, characterized in that: Includes the following: Install the starting bracket and install multiple CNC jacks and reaction frames on both sides of the starting bracket; Hoist the shield onto the starting bracket; Install the shield guidance control system and connect it to the CNC jacks, and adjust the starting posture by controlling the thrust of multiple CNC jacks; Install a propulsion reaction frame behind the starting bracket; Break down the cave entrance; Manually check whether the shield posture is consistent with the starting posture; Install negative ring segments; Seal the cave entrance; During shield tunneling, when the shield body completely enters the soil, the assembly of the ten ring segments is completed and the start is completed; The process of controlling the thrust of multiple numerically controlled jacks to adjust the starting posture is specifically as follows: The maximum offset between the starting axis of the shield cutting line and the line design axis is estimated based on the shield design parameters, and it is judged whether the maximum offset meets the design requirements. If it does not meet the design requirements, the shield design parameters are adjusted; The shield attitude parameters are calculated based on the adjusted shield design parameters; The thrust value of each CNC jack is calculated based on the shield posture parameters; The process of calculating the thrust value of each CNC jack based on the shield posture parameters includes the following: With the cutterhead center point as the origin, the tangent direction of the line design axis as the x-axis direction, the direction of the section along the shield axis and perpendicular to the line design axis as the y-axis direction, and the right-hand positioning to determine the I-axis direction, establish the working space coordinate system for shield posture adjustment; Based on the pre-deflection angle, a transformation matrix from the workspace coordinate system to the pushing direction is constructed, and a CNC jack installation method matrix is ​​constructed; The elongation vector of each CNC jack is obtained based on the geometric relationship, the transformation matrix and the CNC jack installation matrix; The elongation of each CNC jack is calculated based on the elongation vector of each CNC jack, the shield diameter and the shield tail offset, and then the thrust value of each CNC jack is calculated.

2. The shield cutting line starting method according to claim 1, characterized in that: The maximum offset between the starting axis of the shield cutting line and the design axis of the line is estimated based on the following formula: Among them, δ represents the maximum offset, R represents the line design curve radius, and L represents the shield length. When δ is less than or equal to 50 mm, it is determined that the maximum offset meets the design requirements. When δ is greater than 50 mm, it is determined that the maximum offset does not meet the design requirements. By adjusting the shield design parameters R and L, δ is made less than or equal to 50 mm.

3. The shield cutting line starting method according to claim 2, characterized in that: When the line design curve radius R is too small and cannot be adjusted, the maximum offset between the starting axis of the shield cutting line and the line design axis is estimated based on the following formula: Where D is the shield diameter, Δ is the shield tail offset, When δ is less than or equal to 50 mm, it is determined that the maximum offset meets the design requirements. When δ is greater than 50 mm, it is determined that the maximum offset does not meet the design requirements. The shield length L is reduced to make δ less than or equal to 50 mm.

4. The shield cutting line starting method according to claim 1, characterized in that: The transformation matrix is The CNC jack installation matrix is: Where n represents the number of CNC jacks that generate thrust, θ represents the pre-deflection angle, D represents the shield diameter, and i represents the i-th CNC jack.

5. The shield cutting line starting method according to claim 4, characterized in that: The extension vector of the i-th jack is r = [xyz] T +χQ-Q, where x, y, and z represent the relative coordinate transformation of the shield tail edge point relative to the workspace coordinate system. The coordinate transformation can be obtained by geometric relationship and transformation matrix. x A 、y A 、z A They represent the absolute coordinates of the shield tail edge point in the workspace coordinate system, so the extension vector of the i-th CNC jack can be obtained as: Where L represents the shield length and Δ represents the shield tail offset.

6. The shield cutting line starting method according to claim 5, characterized in that: The elongation of the i-th CNC jack is calculated based on the following formula: l i =rτ i -(D+D) Among them, l i represents the extension of the i-th CNC jack, τ i represents the unit direction vector of the extension vector of the i-th CNC jack along the pushing direction, 7. The shield cutting line starting method according to claim 1, characterized in that: After calculating the thrust value of each CNC jack, the following are also included: Determine whether the thrust generated by multiple CNC jacks satisfies the dynamic equations and shield rotation differential equations.

8. The shield cutting line starting method according to claim 7, characterized in that: The kinetic equation is: Among them, P i represents the thrust of the i-th CNC jack, n represents the number of CNC jacks that generate thrust, e yA represents the vector of the shield in the y-axis direction of the workspace coordinate system, f represents the resistance of the shield, m represents the total mass of the shield and the starting bracket, v represents the velocity, and t represents the time; The shield rotation differential equation is: Among them, e zA represents the vector of the shield in the z-axis direction of the workspace coordinate system, χ represents the transformation matrix, Q represents the CNC jack installation matrix, M f represents the restraint torque on the shield, J represents the moment of inertia of the shield around its rotation center, ω represents the angular velocity, L represents the length of the shield, λ represents the resistance coefficient, and a represents the distance between adjacent CNC jacks.

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