Method and system for hob normal force prediction taking into account rotational asymmetry

Abstract

This application relates to the field of tunnel boring equipment technology, and discloses a method and system for predicting the normal force of a cutter roller that takes into account rotational asymmetry. The method includes: obtaining parameters such as rock mass strength, penetration depth, and cutter geometry; calculating and superimposing the areas of the inner and inner compression zones of the cutter roller, and spreading them out to the circumference of the rotation trajectory to determine the cutting groove width; calculating the contact arc using the penetration depth and cutter radius, and deriving the total contact area in conjunction with the cutting groove width; calculating the contact pressure and integrating it along the total contact area to obtain the single cutter rock-breaking resultant force; setting the point of application of the resultant force to pass through the cutter axis and bisect the contact angle corresponding to the contact arc, and decomposing the resultant force to obtain the single cutter rock-breaking normal force. This invention transforms the spatial rock-breaking destruction zone into a planar equivalent integration domain, eliminating the theoretical errors caused by the traditional straight-line cutting assumption and improving the accuracy of the cutter normal force calculation.

Description

Technical Field

[0001] This invention relates to the field of tunnel boring equipment technology, specifically to a method and system for predicting the normal force of the cutter head that takes into account rotational asymmetry. Background Technology

[0002] Tunnel boring machines (TBMs) are widely used in the construction of full-face hard rock tunnels. Accurately predicting the stress on the disc cutters on the cutterhead is of great significance for equipment selection, cutter arrangement, and optimization of tunneling parameters. Currently, the CSM model proposed by the Colorado School of Mines is a commonly used theoretical model for calculating the rock-breaking stress of the disc cutters.

[0003] Existing CSM models typically derive rock-breaking forces from cutterheads based on the assumption of a purely linear cutting trajectory to establish mechanical equations and boundary conditions. However, in actual tunneling, the cutterhead rotates with the cutterhead, and its actual trajectory is a spatial rotation curve. This rotational motion causes differences in the rock failure boundaries on the inner and outer sides during the cutterhead's rock crushing process, resulting in inconsistencies between the actual rock-breaking contact area and spatial morphology and the state under the linear cutting assumption. Because the spatial rotational effect of the cutterhead is not considered, existing calculation methods based on the linear cutting assumption have theoretical biases in solving for the cutting zone area and contact boundary, leading to inaccuracies in the derived total contact area. The bias in the integration domain ultimately causes the calculated single-cutter rock-breaking normal force to deviate from the actual stress situation, reducing the accuracy of CSM model stress prediction under complex tunneling conditions. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and system for predicting the normal force of a cutter that takes into account rotational asymmetry. This solves the problem that existing CSM models, which are based on the assumption of straight-line cutting and do not consider the actual spatial rotation trajectory of the cutter, lead to deviations in the calculation of the rock-breaking contact area, resulting in inaccurate predictions of the normal force of the cutter.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a method for predicting the normal force of a hobbing cutter that takes into account rotational asymmetry, comprising the following steps: Obtain the uniaxial compressive strength, tensile strength, penetration depth, cutter rotation radius, cutter tip width, cutter radius, cutter spacing, dimensionless parameters, and cutter compressive stress distribution coefficient of the rock.

[0006] Calculate the area of ​​the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob. Superimpose the areas of the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob to obtain the cutting area. Distribute the cutting area evenly to the circumference of the rotation trajectory determined by the hob's rotation radius to determine the width of the cutting groove.

[0007] The contact radius is calculated using the penetration depth and the hob radius, and the total contact area is calculated by combining the cutting groove width, the contact radius, and the hob radius.

[0008] The contact pressure is determined based on the uniaxial compressive strength of the rock, the tensile strength of the rock, the cutter spacing, the cutter radius, the cutter tip width, the contact arc, the dimensionless parameters, and the compressive stress distribution coefficient of the cutter. The contact pressure is then integrated along the total contact area to obtain the resultant force of the single cutter breaking the rock.

[0009] The point of application of the resultant force of the roller cutter is set to pass through the center of the roller cutter axis and bisect the contact angle corresponding to the contact arc. The resultant force of the single roller cutter breaking rock is decomposed and the normal force of the single roller cutter breaking rock is calculated.

[0010] In a further implementation, after obtaining the penetration depth, a spatial mileage alignment logic is established to obtain the current tunneling mileage coordinates of the tunnel boring equipment. The rock mass strength parameters corresponding to the tunneling mileage coordinates are called from the pre-entered geological exploration database, and the penetration depth is synchronously bound with the uniaxial compressive strength and tensile strength of the rock.

[0011] In a further embodiment, the process of calculating the area of ​​the normal compression zone and the area of ​​the inner compression zone of the cutter includes: determining the area of ​​the normal compression zone of the cutter by calculating the area of ​​the annular region based on the cutter's rotation radius and tip width; and calculating the area of ​​the inner compression zone of the cutter based on the boundary conditions of the lateral failure depth of the penetrated rock mass, based on the cutter's rotation radius, tip width, cutter radius, and penetration depth. This step transforms the rock damage amounts generated during the rotational motion in different regions of the normal and inner sides into planar geometric parameters, correcting the prediction errors of the traditional CSM model based on the assumption of straight-line cutting.

[0012] In a further embodiment, the process of obtaining the hob rotation radius and the hob compressive stress distribution coefficient includes: confirming the installation position of the target hob to be calculated, extracting the radial distance from the installation center of the target hob to the rotation center of the cutter head as the hob rotation radius; and determining the hob compressive stress distribution coefficient based on the cutter tip width.

[0013] In a further embodiment, when obtaining the hob rotation radius, the hob rotation radius is greater than or equal to the minimum installation radius of the hob; the minimum installation radius of the hob is several times the tip width, to avoid geometric singularities caused by the hob rotation radius being zero during calculation.

[0014] In a further embodiment, the process of calculating the contact arc includes: determining the penetration value; when the penetration is not greater than zero, assigning the contact arc value to zero; when the penetration is greater than zero, calculating the contact arc using the inverse cosine function relationship in combination with the penetration and the hob radius.

[0015] In a further embodiment, the step of calculating the total contact area by combining the cutting groove width, contact arc length, and hob radius includes: based on the equivalent cutting groove principle, the contact arc length determined by the contact arc length and hob radius is taken as the length of the equivalent cutting groove, and the cutting groove width is taken as the width of the equivalent cutting groove. The total contact area is obtained by calculating the area of ​​the equivalent cutting groove. This step extends the planar geometric parameters to three-dimensional space to determine the force integration domain under the hob rotation condition.

[0016] In a further embodiment, the hob is a constant cross-section CCS hob; the obtained tip width is the fixed tip width of the constant cross-section CCS hob in its brand new state, and the value range of the fixed tip width is 10mm to 22mm to avoid calculation errors caused by dividing by zero when determining the contact pressure.

[0017] In a further embodiment, the process of decomposing the resultant force of the single cutter rock breaking includes: using the angular relationship of half the contact arc and the cosine trigonometric function, the resultant force of the single cutter rock breaking is converted into a component perpendicular to the cutter head surface, and the normal force of the single cutter rock breaking is obtained.

[0018] A second aspect of the present invention provides a system for predicting the normal force of a hob that takes into account rotational asymmetry, comprising: The parameter acquisition module is used to acquire rock uniaxial compressive strength, rock tensile strength, penetration depth, cutter rotation radius, cutter tip width, cutter radius, cutter spacing, dimensionless parameters, and cutter compressive stress distribution coefficient.

[0019] The feature extraction module is used to calculate the area of ​​the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob. The cutting area is obtained by superimposing the areas of the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob. The cutting area is then spread out to the circumference of the rotation trajectory determined by the hob's rotation radius to determine the width of the cutting groove.

[0020] The area determination module is used to calculate the contact curvature using the penetration depth and hob radius, and then calculate the total contact area by combining the cutting groove width, contact curvature, and hob radius.

[0021] The force calculation module is used to determine the contact pressure based on the uniaxial compressive strength of the rock, the tensile strength of the rock, the cutter spacing, the cutter radius, the cutter tip width, the contact arc, the dimensionless parameters, and the cutter compressive stress distribution coefficient. The contact pressure is then integrated along the total contact area to obtain the resultant force of a single cutter breaking rock.

[0022] The normal force calculation module is used to set the contact angle corresponding to the point of action of the resultant force of the cutter passing through the cutter axis and bisecting the contact arc, and to decompose the rock-breaking resultant force of a single cutter to calculate the rock-breaking normal force of a single cutter.

[0023] This invention provides a method and system for predicting the normal force of a hobbing cutter that takes into account rotational asymmetry. It has the following beneficial effects: 1. This invention obtains the cutting area by superimposing the area of ​​the normal extrusion zone of the hob and the area of ​​the inner extrusion zone, and then spreads it out to the circumference of the rotation trajectory to determine the width of the cutting groove, thereby deriving the total contact area. This method transforms the calculation logic based on the linear cutting assumption in the traditional model into an equivalent calculation that includes spatial rotation characteristics, eliminates the theoretical error caused by not considering the actual rotation trajectory of the hob, and improves the accuracy of the calculation of the normal force of the hob under different radial installation positions.

[0024] 2. After obtaining the resultant force of a single cutter breaking rock, this invention sets the point of application of the resultant force to pass through the cutter axis and bisect the contact angle corresponding to the contact arc. Based on this condition, the resultant force is decomposed using trigonometric functions. This decomposition method constructs mechanical transformation conditions that conform to the actual rock-breaking contact state of the cutter, so that the calculation of the cutter's normal force and tangential force has a clear geometric and mechanical derivation basis.

[0025] 3. This invention, combined with the actual assembly conditions of TBM engineering, limits the minimum installation radius of the hob rotation radius to no less than several times the tip width, and introduces the tip width of a constant cross-section CCS hob with a fixed size (10mm to 22mm) as a calculation parameter. This eliminates the possibility of the corresponding variable being zero at the physical boundary level. This scheme directly avoids geometric singularities in the calculation of the central cutter region of the model, as well as calculation anomalies caused by the denominator of the formula being zero due to the parameter being zero. This ensures the stability and engineering applicability of the calculation method under the full-disk surface working conditions. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the system architecture of the present invention; Figure 2 This is a flowchart of the method of the present invention; Figure 3 This is a diagram showing the cutting groove features during the rock-breaking process of the rotary cutter of the present invention. Figure 4 This is a diagram showing the contact area between the cutter and the rock during the rotation of the cutting tool of this invention. Figure 5 This is a diagram showing the relationship between the normal force and the radius of rotation in this invention. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see the appendix Figure 1The present invention provides a hobbing cutter normal force prediction system that takes into account rotational asymmetry, including a parameter acquisition module, a feature extraction module, an area determination module, a force calculation module, and a normal force calculation module.

[0029] The parameter acquisition module is used to read the uniaxial compressive strength and tensile strength of the rock corresponding to tunnel construction, record the penetration during the tunnel boring machine's excavation process, and obtain the cutter's slewing radius, tip width, and radius.

[0030] The feature extraction module is used to calculate the area of ​​the normal extrusion zone and the area of ​​the inner extrusion zone of the hob based on the hob rotation radius, tip width, hob radius and penetration, and to calculate the total cutting area of ​​one revolution of the hob and the corresponding cutting groove width.

[0031] The area determination module is used to calculate the contact arc between the cutter and the rock using the penetration depth and the cutter radius. By combining the cutting groove width, contact arc and cutter radius, the total contact area between the cutter and the rock during the rotary rock breaking process is calculated.

[0032] The force calculation module is used to determine the contact pressure between the cutter and the rock based on the uniaxial compressive strength, tensile strength, cutter spacing, cutter radius, cutter tip width, contact arc, dimensionless parameters, and cutter compressive stress distribution coefficient. The contact pressure is integrated along the total contact area to calculate the resultant force of a single cutter breaking the rock. Based on actual engineering conditions, this force calculation module uses the cutter tip width of a constant cross-section CCS cutter with a fixed size for calculation. The value of this fixed cutter tip width ranges from 10mm to 22mm, which avoids the calculation anomaly of division by zero at the physical boundary level.

[0033] The normal force calculation module is used to set the point of application of the resultant force of the cutter to pass through the cutter axis and bisect the contact angle between the cutter and the rock. Based on this condition, the resultant force of a single cutter breaking rock is decomposed and the normal force of a single cutter breaking rock is calculated.

[0034] The modules described above work together to extend the planar mechanics assumptions based on straight-line cutting in the traditional CSM model to a spatial rotational three-dimensional force model that closely reflects the actual working conditions of tunnel boring machines. Through the step-by-step transfer of parameters, the system not only quantifies the asymmetric cutting characteristics caused by the rotary motion of the cutter, but also ensures the robustness of the algorithm through a built-in physical parameter constraint mechanism, thereby effectively improving the accuracy and engineering applicability of single-roller normal force prediction under complex geological conditions across the entire cross-section.

[0035] Please see the appendix Figure 2 This invention provides a method for predicting the normal force of a hob that takes into account rotational asymmetry, comprising the following steps: S10, acquire basic parameters, read the uniaxial compressive strength and tensile strength of rock corresponding to tunnel construction, record the penetration during the tunnel boring machine's excavation process, and acquire the cutter's slewing radius, tip width, and radius. S20, extract the cutting groove features, and calculate the area of ​​the normal extrusion zone and the area of ​​the inner extrusion zone of the hob according to the hob rotation radius, tip width, hob radius and penetration, respectively. Calculate the total cutting area of ​​one revolution of the hob and the corresponding cutting groove width. S30, determine the contact area, calculate the contact arc between the cutter and the rock using the penetration and cutter radius, combine the cutting groove width, contact arc and cutter radius to calculate the total contact area between the cutter and the rock during the rotary rock breaking process; S40, solve the rock breaking force. Determine the contact pressure between the cutter and the rock based on the uniaxial compressive strength of the rock, the tensile strength of the rock, the cutter spacing, the cutter radius, the cutter tip width, the contact arc, the dimensionless parameters, and the cutter compressive stress distribution coefficient. Integrate the contact pressure along the total contact area to calculate the resultant force of a single cutter breaking the rock. S50, decompose the normal force. Set the point of application of the resultant force of the cutter to pass through the cutter axis and bisect the contact angle between the cutter and the rock. Based on this condition, decompose the resultant force of the single cutter breaking the rock and calculate the normal force of the single cutter breaking the rock.

[0036] Before establishing the computational model, this embodiment needs to systematically extract multi-source characteristic variables that affect the force on the hob, and construct a preliminary data environment that reflects the actual physical failure process. The basic parameter acquisition step S10 specifically includes the following processes: In this embodiment, step S101 involves obtaining the geological parameters corresponding to tunnel construction. This includes reading the uniaxial compressive strength of the rock strata where the tunnel is located. Tensile strength of rock The physical basis for selecting this type of parameter lies in the uniaxial compressive strength of the rock. Tensile strength of rock The geological parameters determine the rock mass's resistance to failure and are prerequisite data for calculating the contact pressure of the cutter head and the crack propagation threshold. During engineering implementation, these geological parameters are extracted from the tunnel's preliminary geological exploration report or the results of indoor rock mechanics tests on rock cores. For geological exploration sampling and indoor rock mechanics testing, those skilled in the art can refer to current geotechnical engineering investigation standards; these are well-known techniques in the field and will not be elaborated upon here.

[0037] Based on the static geological parameters obtained above, step S102 is executed to obtain the construction operation parameters of the tunnel boring machine under its current operating state. The penetration depth during the tunnel boring machine's excavation process is recorded. Penetration Defined as the axial depth to which the target cutter head penetrates the rock face per revolution of the cutterhead, it characterizes the current rock-breaking progress of the tunneling equipment. To ensure the matching of dynamic working conditions with the static geological environment, spatial mileage or timestamp alignment logic needs to be established to incorporate the real-time recorded penetration depth. Uniaxial compressive strength of the rock corresponding to this tunneling section and rock tensile strength Synchronous binding is performed; when spatial mileage alignment is adopted, the system obtains the current tunneling mileage coordinates of the tunnel boring equipment, automatically matches and calls the corresponding rock mass strength parameters of that mileage segment from the pre-entered geological exploration database, thereby achieving precise binding between dynamic construction data and static geological data. This penetration depth value is automatically recorded and output in real time by the tunnel boring equipment's control panel. The specific sensing acquisition method used by the equipment's automatic recording system is understood by those skilled in the art to be reading data through stroke sensors or the main control programmable logic controller, and will not be elaborated further here.

[0038] After aligning the geological and operational conditions, proceed to step S103 to obtain the physical structure parameters and cutterhead arrangement parameters of the hob. Confirm the hob rotation radius of the target hob to be calculated. hob radius Wide blade tip Hob cutter spacing and the compressive stress distribution coefficient of the hobbing cutter Hob rotation radius The radial distance from the hob mounting center to the cutter head rotation center; the hob rotation radius at different mounting positions. This directly determines the spatial curvature of the subsequent cutting trajectory. Tool tip width With hob radius These are the factory-designed structural dimensions of the hob itself. Hob pitch The distance between two adjacent cutter rock-breaking trajectories on the cutterhead is introduced because its physical relevance lies in determining the degree of convergence and penetration of the stress fields within the rock mass between adjacent cutters. (Cutting cutter compressive stress distribution coefficient) This parameter reflects the stress distribution at the contact surface between the hob and the rock, typically varying between -0.2 and 0.2. Its specific value is related to the tip width, and it decreases as the tip width of a standard cross-section CCS hob increases. (Dimensionless parameter) Approximately equal to 2.12. The above cutterhead and arrangement parameters are recorded based on the instruction manual and cutterhead design drawings of the specific tunnel boring machine used in the project.

[0039] Through the above settings in this embodiment, the extraction of three core basic data types—geological environment, operating conditions, and mechanical structure—was completed, and the initial values ​​for calculation were determined, thus establishing a data foundation for the subsequent derivation of the geometric features and mechanical model of the fusion cutter's rotary motion trajectory.

[0040] Traditional CSM (Cut-Side Mechanism) mechanical models are mostly based on the assumption of planar force, assuming that the cutter head cuts rock along a straight trajectory. In actual tunnel boring machine (TBM) construction, the cutterhead drives the cutter head to revolve around the center of the cutterhead, and its cutting trajectory is a spatial circular arc. This rotational effect leads to an asymmetrical distribution of the failure range of the rock mass on both sides of the cutter head. To overcome the limitations of traditional linear models, in this embodiment, the system performs a step S20 to extract cutting groove features, aiming to transform the spatially rotating cutting trajectory features into planar geometric analytical parameters that can be used for force calculation.

[0041] Based on the rock-breaking geometric constraints, step S20, which extracts the cutting groove features, is specifically divided into the following sub-steps: In this embodiment, sub-step S201 is executed based on the obtained hob rotation radius. and the width of the knife tip Determine the area of ​​the normal extrusion zone of the hobbing cutter. This area physically characterizes the width of the blade tip. A ring-shaped region of rock directly crushed during rotary motion. Area of ​​the normal compression zone of the roller cutter. The calculation formula is as follows: ; In the formula, This represents the area of ​​the normal extrusion zone of the hobbing cutter; The radius of rotation of the hob is in mm; The blade tip width is in mm. The radius of the hob is in mm. Penetration depth, in mm.

[0042] Based on the above basic region calculations, the system executes sub-step S202, based on the hob rotation radius. Wide blade tip hob radius With penetration Determine the area of ​​the inner extrusion zone of the hob. Its geometric meaning can be equivalent to the degree of penetration. Boundary conditions for the lateral failure depth formed by cutting into the rock mass and the radius of the cutter. The lateral enlargement annular area is jointly determined. The area of ​​the inner extrusion zone of the cutter head. The calculation formula is as follows: ; In the formula, This represents the area of ​​the inner extrusion zone of the hob; the Chinese meanings of the other symbols in the formula are consistent with the aforementioned content.

[0043] After solving for each independent failure region, continue with sub-step S203 to calculate the area of ​​the normal extrusion zone of the rolling cutter. Area of ​​the inner extrusion zone of the hob Superimpose the data to obtain the cutting area. The cutting area This reflects the macroscopic projection of the rock-breaking volume of a single hobbing cutter over one complete rotation cycle onto the cross-section. Cutting area. The calculation formula is as follows: ; In the formula, This represents the cutting area.

[0044] To establish a mathematical relationship between the total cutting area and the local forces, sub-step S204 is executed in this embodiment to calculate the width of the cutting groove. Based on the principle of area equivalence, the spatial destruction area containing rotational features is evenly distributed across the circumference of the hob's rotational trajectory. Cutting groove width. The calculation formula is as follows: ; In the formula, The width of the cutting groove is given. In this formula, because the gyration radius of the hob is greater than or equal to the minimum installation radius of the hob in the actual tunnel boring machine cutterhead arrangement, and this minimum installation radius is several times the cutter tip width, the denominator term, hob gyration radius, will not approach zero. Based on the above realistic physical structural constraints, the system naturally eliminates the calculation anomaly of division by zero during calculation, ensuring the calculation stability of the model when facing the full-disk surface working condition.

[0045] In actual tunnel boring machine cutterhead arrangements, the central cutter located in the center of the cutterhead primarily operates through rotation, sliding, and in-situ compression, exhibiting a highly curved cutting trajectory. Conversely, the front and edge cutters, located further from the center, exhibit distinct revolution and rotation characteristics in rock breaking. This embodiment introduces realistic physical boundary conditions for the hobbing cutter installation, enabling the model to directly reflect the actual cutting trajectory characteristics at each installation location. This avoids the calculation errors caused by the traditional model's assumption of a single force on all cutters.

[0046] Please see the appendix Figure 3 This invention also provides a characteristic diagram of the cutting groove during the rock-breaking process of a rotary cutter. For example... Figure 3 As shown in the figure, O represents the rotation center of the cutter head. When the hob performs spatial arc cutting along the rotation trajectory, the projection of its cutting groove on the plane can be divided into two parts: the inner extrusion zone of the hob (labeled in English in the figure as...). ) and the normal extrusion zone of the hobbing cutter (labeled in English in the figure) The AA section view in the figure shows the longitudinal cross-sectional shape of the hob cutting groove and the distribution of the initial crushing zone. The figure also clearly shows the width of the cutting groove. With the rotation radius of the hob The pattern of change: Under the same conditions such as penetration depth, as the hob installation position is further away from the center of rotation, that is, the hob rotation radius increases (e.g., The width of the cutting groove obtained by equivalently distributing the damaged volume gradually decreases (i.e., This intuitively reflects the asymmetric influence of the rotary cutter effect on the spatial distribution of rock damage areas.

[0047] After extracting the cutting groove features and obtaining its planar analytical parameters, the system needs to extend the two-dimensional cutting groove width to three-dimensional space. In this embodiment, the system performs step S30 to determine the contact area.

[0048] In this embodiment, sub-step S301 is executed, utilizing penetration. and hob radius Calculate the contact radius To ensure the completeness of the system logic, the system reads the penetration degree before calculation. If determined If no effective cut-in occurs, the contact radius is assigned a value of zero; if the determination is... Then the contact radius is executed. Analytical calculation: ; In the formula, Contact radius, in rad; Where is the radius of the hob.

[0049] After obtaining the spatial longitudinal depth parameters, the system further executes sub-step S302, deriving the contact area during the rotary rock breaking process based on the equivalent cutting groove principle. Contact area The calculation formula is as follows: ; In the formula, This represents the contact area. This value closely approximates the actual eccentric loading rock-breaking contact state at the physical boundary, providing an accurate spatial integration domain benchmark for subsequent calculation of the rock-breaking resultant force.

[0050] After reconstructing the three-dimensional total contact area reflecting the rotary cutter effect, the system executes step S40 to solve the rock-breaking force. The system transforms microscopic mechanical characteristics into macroscopic rock-breaking mechanical loads using the area integration principle. The basic principle is to first quantitatively determine the contact area during the rotary rock-breaking process. Then, the contact pressure in the CSM model Along the contact area Points are earned to obtain the combined rock-breaking power of a single rolling cutter. The calculation formula is as follows: ; In the formula, the resultant force of a single rolling cutter breaking rock The unit is N; For contact pressure.

[0051] In this embodiment, sub-step S401 is executed to determine the contact pressure based on the geological and mechanical layout parameters. Contact pressure The calculation formula is as follows: In this formula, since the CCS hob with a constant cross section is used in the actual engineering process and has a fixed tip width, the value ranges from about 10mm to 22mm. This physical property requirement ensures that the denominator will not approach zero, thus avoiding the calculation risk of division by zero from a physical perspective.

[0052] Obtain contact pressure Then, sub-step S402 is executed to calculate the resultant force of a single roller cutter breaking rock. Single-roll cutter rock-breaking combined force The calculation formula is as follows: After obtaining the resultant force of the single cutter rock breaking, the system needs to convert it into the orthogonal component force required for equipment control. In this embodiment, the system performs the decomposition of normal force step S50.

[0053] In this embodiment, sub-step S501 is executed to establish the geometric constraints for mechanical decomposition. The theoretical analysis assumes that the point of application of the resultant force of the hob passes through the hob axis and bisects the contact angle between the hob and the rock (i.e.,...). This setting satisfies the static premise of stable rotation during rock breaking by a roller cutter.

[0054] Based on the above equivalent force boundary conditions, the system executes sub-step S502, from which the ratio of the hob tangential force to the normal force can be obtained: ; In the formula, This refers to the tangential force of the hobbing cutter. This represents the normal force for rock breaking with a single roller cutter. The system utilizes the contact curvature. Half of the angular relationship is used to convert the load into a component perpendicular to the cutterhead surface through cosine trigonometric functions. Single-roll cutter rock-breaking normal force. The calculation formula is as follows: Please see the appendix Figure 4 The present invention also provides a diagram of the contact area between the cutter and the rock during the rotation of the cutter and a schematic diagram of the force decomposition. For example... Figure 4The upper part of the diagram shows the rotation direction of the cutter and the X and Y coordinate system. Point A is the lowest point of the cutter, and point B is the initial contact point where the cutter cuts into the rock surface. The specific meanings of the English letters and physical symbols in the diagram are as follows: The contact pressure between the cutter and the rock is distributed radially on the contact surface; Penetration degree; Where is the hob radius; Contact curvature; The angle that bisects the contact arc (i.e. ); This represents the rock-breaking resultant force of a single hob cutter along the contact angle bisector and pointing towards the axis (equivalent to the force described above). ); Represents the normal force that is vertically downward. This represents the horizontal tangential force of the rolling cutter.

[0055] like Figure 4 The lower half shows the projected shape (trapezoidal) of the contact area on the rock surface. The width of the front end of this projected area is the width of the knife tip. The width of the rear end is equal to the width of the cutting groove. The longitudinal length of the projection is The light blue areas on either side of the shaded region in the figure visually indicate the increased contact area due to rotation, illustrating the physical nature of why the rock-breaking contact area is larger than the traditional straight-line cutting area after incorporating the hobbing rotation effect into the CSM model.

[0056] The following is a specific implementation example: a subway project is used as an example. The parameters of the composite earth pressure balance shield cutterhead used in this project are as follows: cutterhead radius... =216mm, blade tip width =19mm, hobbing cutter spacing =100mm, compressive stress distribution coefficient of hobbing cutter =0, dimensionless parameter =2.12. Taking the geological conditions and operating status when the project reached the 505th ring as an example, detailed steps are given to calculate the rock-breaking force of a single cutter at a cutter rotation radius of 0.4m when the project reached that point. The rock-breaking load at other locations and other rotation radii can be calculated using the same method.

[0057] The geological parameters used in the calculations were all taken from the geological report. The geological parameters for the 505th ring of this project are as follows: uniaxial compressive strength of rock. =32.8MPa, rock tensile strength =2.343MPa. All operating parameters involved in the calculations were automatically recorded by the equipment. The operating parameters for this project when tunneling reached the 505th ring were: penetration depth... =12.6mm.

[0058] (1) Calculate the area of ​​the normal extrusion zone of the hobbing cutter. Area of ​​the inner extrusion zone of the hob : Depend on Calculations yielded =47752.21mm 2 .

[0059] Depend on Calculations yielded =16601.56mm 2 .

[0060] (2) Calculate the cutting area of ​​the hob in one revolution. and the width of the cutting groove : Depend on Calculations yielded =64353.77mm 2 ; Depend on Calculations yielded =25.61mm.

[0061] (3) Calculate the contact area between the cutter and the rock. : Depend on Calculations yielded =1653.56mm 2 .

[0062] (4) Calculate the contact pressure between the cutter and the rock. : Depend on Calculations yielded =47.80MPa.

[0063] (5) Calculate the resultant force of a single roller cutter breaking rock. : Depend on Calculated =79042.19N.

[0064] (6) Calculate the normal force of a single roller cutter breaking rock. and tangential force : Depend on Calculated =77880.96N.

[0065] At this point, the calculation has been completed. =32.8MPa =2.343MPa, penetration depth The rock-breaking load of a single cutter head with a rock thickness of 12.6 mm and a slewing radius of 0.4 m can be determined using the same method for other rock strengths, slewing radii, and operating conditions. This provides a scientific and effective data basis for the construction and design of tunnel boring equipment.

[0066] At the construction control level, the high-precision single-roll cutter normal force data calculated and output can be fed back to the main control console of the tunnel boring machine in real time, which can be used to dynamically guide the fine adjustment of the total thrust parameters of the whole machine and prevent the cutter from breaking due to local thrust overload. At the early equipment design level, given that this model reveals a significant surge in normal force under small turning radius, this load data can provide more reliable mechanical pre-input parameters for the cutterhead cutter arrangement design (especially the dense arrangement strategy of cutter spacing in the central area of ​​the cutterhead) and the prediction of cutter wear throughout the entire life cycle.

[0067] Calculate the rock-breaking load corresponding to different radii of rotation of the cutter under the geological and operational conditions, and provide a trend diagram of the rock-breaking load of a single cutter with respect to the radius of rotation. Figure 5 As shown in the figure, compared to the CSM model, the improved CSM model of this invention can reflect the variation of rock-breaking load with the radius of rotation. Furthermore, because rotation increases the contact area between the cutter and the rock, the improved CSM model of this invention calculates a larger rock-breaking load. As shown in the figure, compared to the traditional CSM model, the improved CSM model of this invention can accurately reflect the normal force. The variation law with the radius of rotation; and because the rotation of the cutter increases the contact area with the rock, the improved CSM model calculates... The value is larger. This improved CSM model gives... The variation pattern is basically consistent with the results of engineering experiments and indoor experiments, which confirms the rationality of the model.

[0068] Please see the appendix Figure 5 This figure further quantifies the relationship between the normal force and the radius of rotation of the present invention. The horizontal axis represents the radius of rotation of the hob (units are labeled in mm, corresponding to the equivalent scale value in actual engineering practice in the aforementioned embodiments), and the vertical axis represents the normal force. (Unit: kN, i.e., kilonewtons). The horizontal broken line with squares in the figure represents the calculation result of the traditional CSM model, and the descending curve with circles represents the calculation result of the improved CSM model of this invention.

[0069] From the appendix Figure 5 The comparison shows that the traditional CSM model, based on the assumption of straight-line cutting, fails to account for the influence of the radius of gyration, resulting in an inaccurate calculation of the normal force. The normal force remains a constant of approximately 66 kN regardless of the installation location; however, the improved CSM model of this invention, by taking into account the increased off-center contact area due to rotational motion, calculates a higher normal force. The overall size is relatively large. Furthermore, as the hob's rotation radius increases, the rotational effect gradually weakens, and the normal force... It exhibits a nonlinear decay trend and gradually approaches the traditional model; while at a smaller turning radius (such as the region of 0.2 to 0.6 on the horizontal axis), the normal force increases significantly, which provides accurate theoretical calculation support for the phenomenon that hobs in the central area of ​​the cutter head are easily worn and damaged in actual engineering.

Claims

1. A method for predicting the normal force of a hobbing cutter that takes into account rotational asymmetry, characterized in that, Includes the following steps: Obtain the uniaxial compressive strength, tensile strength, penetration depth, cutter rotation radius, cutter tip width, cutter radius, cutter spacing, dimensionless parameters, and cutter compressive stress distribution coefficient of the rock. Calculate the area of ​​the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob, and superimpose the area of ​​the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob to obtain the cutting area. Spread the cutting area evenly to the circumference of the rotation trajectory determined by the hob's rotation radius to determine the width of the cutting groove. The contact arc is calculated using the penetration depth and the hob radius, and the total contact area is calculated by combining the cutting groove width, the contact arc, and the hob radius. The contact pressure is determined based on the uniaxial compressive strength of the rock, the tensile strength of the rock, the cutter spacing, the cutter radius, the cutter tip width, the contact arc, the dimensionless parameter, and the cutter compressive stress distribution coefficient. The contact pressure is then integrated along the total contact area to obtain the single cutter rock-breaking resultant force. The point of application of the resultant force of the roller cutter is set to pass through the center of the roller cutter axis and bisect the contact angle corresponding to the contact arc. The resultant force of the single roller cutter breaking rock is decomposed and the normal force of the single roller cutter breaking rock is calculated.

2. The method according to claim 1, characterized in that, After obtaining the penetration depth, a spatial mileage alignment logic is established to obtain the current tunneling mileage coordinates of the tunnel excavation equipment. The rock mass strength parameters corresponding to the tunneling mileage coordinates are called from the pre-entered geological exploration database, and the penetration depth is synchronously bound with the uniaxial compressive strength and tensile strength of the rock.

3. The method according to claim 1, characterized in that, The process of calculating the area of ​​the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob includes: Based on the hob rotation radius and the cutter tip width, the area of ​​the hob normal extrusion zone is determined by calculating the area of ​​the annular region. Based on the cutting roller's rotation radius, tip width, radius, and penetration depth, the area of ​​the inner compression zone of the cutting roller is calculated according to the boundary conditions of the lateral failure depth of the penetrated rock mass.

4. The method according to claim 1, characterized in that, The process of obtaining the hob rotation radius and the hob compressive stress distribution coefficient includes: Confirm the installation position of the target hob to be calculated, and extract the radial distance from the installation center of the target hob to the rotation center of the cutter head as the hob rotation radius; The compressive stress distribution coefficient of the hobbing cutter is determined based on the cutter tip width.

5. The method according to claim 1, characterized in that, When obtaining the hob rotation radius, the hob rotation radius is greater than or equal to the minimum installation radius of the hob; The minimum installation radius of the hob is several times the width of the cutter tip to avoid geometric singularities caused by the hob's rotation radius being zero during calculation.

6. The method according to claim 1, characterized in that, The process of calculating the contact curvature includes: Determine the penetration value; When the penetration is not greater than zero, the contact curvature is set to zero; When the penetration is greater than zero, the contact arc is calculated by combining the penetration and the hob radius using the inverse cosine function relationship.

7. The method according to claim 1, characterized in that, The step of calculating the total contact area by combining the cutting groove width, the contact arc, and the hob radius includes: Based on the principle of equivalent cutting groove, the contact arc length determined by the contact arc and the hob radius is taken as the length of the equivalent cutting groove, and the cutting groove width is taken as the width of the equivalent cutting groove. The total contact area is obtained by calculating the area of ​​the equivalent cutting groove.

8. The method according to claim 1, characterized in that, The hob is a constant cross-section CCS hob. The obtained tip width is the fixed tip width of the constant cross-section CCS hob in its brand-new state. The value range of the fixed tip width is 10mm to 22mm to avoid calculation errors caused by dividing by zero when determining the contact pressure.

9. The method according to claim 1, characterized in that, The process of decomposing the resultant force of the single roller cutter breaking rock includes: Using the angular relationship of half the contact arc and the cosine trigonometric function, the resultant force of the single cutter rock breaking is converted into a component perpendicular to the cutterhead surface, thus obtaining the normal force of the single cutter rock breaking.

10. A hobbing cutter normal force prediction system that takes into account rotational asymmetry, characterized in that, The method for predicting the normal force of a hob, taking into account rotational asymmetry, as described in any one of claims 1-9, includes: The parameter acquisition module is used to acquire rock uniaxial compressive strength, rock tensile strength, penetration, cutter rotation radius, cutter tip width, cutter radius, cutter spacing, dimensionless parameters, and cutter compressive stress distribution coefficient. The feature extraction module is used to calculate the area of ​​the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob, and to obtain the cutting area by superimposing the area of ​​the normal extrusion zone of the hob and the area of ​​the inner extrusion zone of the hob. The cutting area is then spread out to the circumference of the rotation trajectory determined by the rotation radius of the hob to determine the width of the cutting groove. The area determination module is used to calculate the contact arc using the penetration and the hob radius, and to calculate the total contact area by combining the cutting groove width, the contact arc and the hob radius; The force calculation module is used to determine the contact pressure based on the uniaxial compressive strength of the rock, the tensile strength of the rock, the cutter spacing, the cutter radius, the cutter tip width, the contact arc, the dimensionless parameter and the cutter compressive stress distribution coefficient, and to obtain the single cutter rock-breaking resultant force by integrating the contact pressure along the total contact area. The normal force calculation module is used to set the point of application of the resultant force of the roller cutter to pass through the center of the roller cutter and bisect the contact angle corresponding to the contact arc, and to decompose the rock-breaking resultant force of the single roller cutter to calculate the rock-breaking normal force of the single roller cutter.

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