A tunneling face excavation method based on jet cutting

Abstract

The present invention relates to tunnel underground engineering, and specifically to a tunnel excavation face excavation method based on jet cutting, comprising the following steps: S1, in the working area, cutting test is carried out to obtain the cutting depth under different nozzle moving speeds; S2, the face is divided into regions to obtain a plurality of working areas; S3, the rock blocks in the working area are cut layer by layer from top to bottom, the nozzle first cuts along a preset horizontal path below the rock block in an oblique upward cutting manner, and then cuts along a preset horizontal path above the rock block in an oblique downward cutting manner, the oblique upward cutting surface intersects with the oblique downward cutting surface, so that the rock block is peeled off and leaves the working area. It can make full use of the ground stress and the deadweight of the rock block, reduce the cutting depth required for the rock block to fall, increase the nozzle moving speed, and improve the overall excavation efficiency; and the use of jet cutting can effectively overcome the damage to the tool caused by the bad geological conditions and strata, and reduce the construction cost.

Description

Technical Field

[0001] The invention relates to underground tunnel engineering, and in particular to a tunnel boring face excavation method based on jet cutting. Background Art

[0002] In recent years, my country's tunnel and underground engineering technology has developed rapidly. In terms of the scale and number of tunnel construction, China has become a world tunnel power. The proportion of tunnel and underground engineering construction in infrastructure construction has been increasing year by year. The construction volume of tunnels, urban subways and underground space projects in my country has increased year by year. The strata they pass through are complex, and they are faced with a large number of hard strata excavation and excavation. Traditional rock construction methods (drilling and blasting, cantilever tunneling, TBM method) have serious tool wear, large vibration of drilling and blasting, serious damage to surrounding rocks, especially a great impact on urban structures and residents, low excavation efficiency, high construction cost, and high risk. Therefore, it is urgent to break through the inherent thinking inertia of traditional mechanical extrusion, grinding and crushing, and drilling and blasting excavation, and explore a new hard rock excavation method.

[0003] CN104314573A discloses a hard rock tunnel construction method based on hydraulic cutting, which uses a hydraulic cutter to cut the face into multiple rectangular cutting blocks, and uses a hydraulic splitter to split along the horizontal cutting seam or the vertical cutting seam, and splits the multiple rectangular cutting blocks from the excavation section of the current cutting section. Compared with the traditional drilling and blasting method, the excavation control accuracy is improved, and the environmental disturbance is small. However, due to the limited ability of hydraulic cutting, the depth of the cutting seam is difficult to make the rock blocks easily peeled off. At the same time, a hydraulic splitter is required for use. During the excavation process, the hydraulic cutter and the hydraulic splitter need to be continuously switched at the excavation section position, which is complicated to operate and affects the excavation efficiency.

[0004] CN113153336A discloses a high-pressure abrasive water jet excavation method, which uses an abrasive water jet to divide the tunnel face into grids, then inserts a radial nozzle into the slot to cut the rock root, and then removes the rock from the tunnel face. Although this method achieves hydraulic cutting and crushing of the entire cross-section of the tunnel face, it still has the following problems: 1) The slot width produced by a single cut of the rock by the abrasive water jet is limited, and it is difficult to insert the radial nozzle, requiring reciprocating cutting or using a larger nozzle, which affects efficiency; 2) The radial nozzle needs to be inserted into the crack or hole of the rock during cutting, and the control of its cutting ability is not intuitive, and it is difficult to judge whether the rock has been cut through. In addition, in the abrasive water jet, single hole blockage is prone to occur, but it is difficult to detect when it is in the rock.

[0005] CN117027836A discloses a method for intelligent tunneling of hard rock face metamorphic water jets. The method establishes an intelligent database for rock breaking with abrasive jets and corresponds it to the color of the rock; uses a camera to capture the distribution characteristics of face rock samples and divide the contour lines of different metamorphic cells on the face; uses a rotating abrasive water jet to drill the center hole of the metamorphic cell according to the pre-drilling results, the data in the intelligent database, and the positions of the contour lines of different metamorphic cells on the face; uses a double-strand abrasive water jet to rotate and remove the rock, and then uses a single-strand abrasive water jet to cut the remaining hard rock. The use of this method involves face image recognition and an intelligent database, but the tunnel is dusty and the light is weak, and the accuracy of image recognition is difficult to control. The control of the radial nozzle cutting ability is not intuitive, and it is difficult to judge whether the rock has been cut through. In addition, in the abrasive water jet, single hole blockage is prone to occur. When using a double-strand abrasive water jet to rotate and remove the rock in the hole, in order to ensure the cutting range, the cutting path overlaps in many places, affecting the efficiency. Summary of the invention

[0006] The purpose of the present invention is to provide a tunneling face excavation method based on jet cutting, which can make full use of the ground stress and the deadweight of the rock blocks, reduce the cutting depth required for the rock blocks to fall, increase the nozzle movement speed, and improve the overall tunneling and excavation efficiency; and the use of jet cutting can effectively overcome the damage to the tool caused by poor geological conditions and strata, and reduce construction costs.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A tunneling face excavation method based on jet cutting comprises the following steps:

[0009] S1, in the working area, the cutting test of the tunnel face is carried out using the jet cutting equipment at different nozzle moving speeds to obtain the cutting depth at different nozzle moving speeds;

[0010] S2, dividing the tunnel face into regions to obtain a number of working regions; the jet ejected from the nozzle of the jet cutting equipment moves along the preset contour line of the working region to cut the rock mass to form a cutting contour line;

[0011] S3, cutting and peeling off the rock blocks in the working area layer by layer from top to bottom. The cutting and peeling off of a single rock block includes: the nozzle first cuts along a preset horizontal path below the rock block in an oblique upward cutting manner to obtain an oblique upward cutting surface; then the nozzle cuts along a preset horizontal path above the rock block in an oblique downward cutting manner to obtain an oblique downward cutting surface; the oblique upward cutting surface intersects with the oblique downward cutting surface, so that the rock block peels off and leaves the working area.

[0012] Furthermore, the designed cutting depth B1 of the oblique downward cutting surface satisfies 0.8B≤B1≤0.9B, where B is the designed cutting depth of the oblique upward cutting surface.

[0013] Furthermore, the preset contour lines of the working area in S2 include an actual contour line on the outer edge of the tunnel face and a plurality of separation contour lines located within the tunnel face.

[0014] Furthermore, the determination of the actual contour line of the outer edge of the tunnel face includes:

[0015] Determine and solve the mapping function of the tunnel: Where ω(ζ) is the mapping function; k is a positive integer; C k is the kth real coefficient related to the tunnel section size, ζ is the conformal mapping plane, and the coordinates of the point on the ζ plane ζ=ξ+η=ρe iθ , ξ is the vertical axis, η is the horizontal axis, i is the imaginary unit, ρ is the radius of the unit circle, and θ is the angle between the line connecting a point on the unit circle and the origin of the coordinate system and the ξ axis;

[0016] According to the calculation formula The displacement component u of the inner boundary of the surrounding rock is calculated ρ and u θ , where G is the shear elastic modulus, к = 3-4μ, μ is the Poisson's ratio of the surrounding rock, and ψ(ζ) are analytical functions of stress in unsupported tunnel;

[0017]

[0018] Where P is the pressure on the tunnel model at infinity, λ is the lateral pressure coefficient, σ = ζ, S k is the real coefficient of the kth term, a j is the real coefficient of the jth term, is the stress analytical function of the outer domain of the unit circle on the ζ plane;

[0019] Based on the design contour of the surrounding rock face and the displacement component u of the inner boundary of the surrounding rock ρ and u θ Determine the actual contour line of the outer edge of the tunnel face.

[0020] Furthermore, the separation contour line in the tunnel face is comprehensively determined according to the surrounding rock characteristics, the jet cutting equipment and the size of the tunnel face.

[0021] Furthermore, when the nozzle cuts obliquely upward or obliquely downward, the incident angle between the jet ejected by the nozzle and the tunnel face is 30 to 60 degrees.

[0022] Furthermore, when the nozzle cuts obliquely upward or obliquely downward, the incident angle between the jet ejected by the nozzle and the tunnel face is 45°.

[0023] Furthermore, the cutting depth D of the cutting contour line satisfies 1.4B≤D≤1.6B, where B is the designed cutting depth of the oblique upward cutting surface.

[0024] Beneficial effects of the present invention:

[0025] 1. The present invention adopts an oblique cutting method to achieve the cutting and peeling of rock blocks, fully utilizes the ground stress and the deadweight of the rock blocks, reduces the cutting depth required for the rock blocks to fall, increases the moving speed of the nozzle, and improves the overall excavation efficiency. The use of jet cutting can effectively overcome the damage to the tool caused by poor geological conditions and strata, does not require a cutterhead and a roller, and reduces the construction cost.

[0026] 2. The present invention makes full use of the low damage and low disturbance characteristics of jet cutting to the surrounding rock, has strong adaptability, effectively controls the occurrence of rock burst or large deformation of the tunnel surrounding rock, makes the cutting contour line smooth, calculates the contour line range through ground stress and surrounding rock characteristics, effectively reduces over-excavation and under-excavation, and controls engineering costs;

[0027] 3. The present invention makes full use of the cutting capacity of the jet cutting equipment, without repeated cutting paths. Starting from the third round of cutting, the cut rocks are all in the shape of rectangular strips, and the width of the cross-section of the rectangular strip rock block is the designed cutting depth, ensuring the shortest cutting path and the largest rock fragments, thereby improving the excavation efficiency.

[0028] 4. The specific rock cutting of the present invention follows the principle of first down and then up, which avoids falling rocks hitting the nozzle and jet cutting equipment. Only straight nozzle cutting is used to ensure intuitive and accurate control of cutting capacity and cutting effect.

[0029] 5. The cutting path of the present invention is simple in design and has stronger environmental adaptability. It can be designed for regional excavation and cutting in large-section tunnels with low surrounding rock grade or where the equipment working height is limited and full-section excavation cannot be performed, thereby expanding the application scenario range of jet cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic flow chart of a tunneling face excavation method based on jet cutting in an embodiment of the present invention.

[0031] Figure 2 It is a panoramic schematic diagram of the construction area described in the present invention.

[0032] Figure 3 It is a schematic diagram of the tunnel face morphology described in the present invention.

[0033] Figure 4 It is a schematic diagram of the first round of cutting of the tunnel face and the cross section after cutting according to the present invention.

[0034] Figure 5It is a schematic diagram of the second round of cutting of the tunnel face and the cross section after cutting according to the present invention.

[0035] Figure 6 It is a schematic diagram of vertically dividing the tunnel face into regions according to the present invention.

[0036] Figure 7 It is a schematic diagram of horizontal area cutting of the tunnel face according to the present invention.

[0037] Figure 8 It is a schematic diagram comparing the designed cutting depth B1 of the oblique downward cutting surface and the designed cutting depth B of the oblique upward cutting surface.

[0038] In the figure, 1 is the tunnel face, 2 is the preset contour line, 21 is the actual contour line of the outer edge of the tunnel face, 22 is the separation contour line, 3 is the nozzle, 4 is the rock block, and 5 is the cutting section. DETAILED DESCRIPTION

[0039] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0040] In one embodiment, see Figure 1 As shown, the present invention provides a tunneling face excavation method based on jet cutting, which comprises the following steps:

[0041] S1, in the working area, the jet cutting equipment is used to conduct cutting tests on the tunnel face at different nozzle moving speeds to obtain the cutting depth at different nozzle moving speeds.

[0042] S2, dividing the tunnel face into regions to obtain a plurality of working regions; the jet ejected from the nozzle of the jet cutting equipment moves along a preset contour line of the working region to cut the rock mass to form a cutting contour line.

[0043] S3, cutting and peeling off the rock blocks in the working area layer by layer from top to bottom. The cutting and peeling off of a single rock block includes: the nozzle first cuts along a preset horizontal path below the rock block in an oblique upward cutting manner to obtain an oblique upward cutting surface; then the nozzle cuts along a preset horizontal path above the rock block in an oblique downward cutting manner to obtain an oblique downward cutting surface; the oblique upward cutting surface intersects with the oblique downward cutting surface, so that the rock block peels off and leaves the working area.

[0044] The following is an explanation of the specific steps:

[0045] S1, in the working area, the jet cutting equipment is used to conduct cutting tests on the tunnel face at different nozzle moving speeds to obtain the cutting depth at different nozzle moving speeds.

[0046] Determine the nozzle movement speed and cutting depth under the current lithology characteristics and ground stress, such as Figure 2 and Figure 3 As shown, the tunnel face 1 to be cut is leveled, and in the working area, the jet cutting equipment is used to conduct cutting tests on the tunnel face 1 at different nozzle moving speeds to obtain the relationship between the nozzle moving speed and the cutting depth, and the cutting depth at different nozzle moving speeds is obtained. According to the actual tunnel excavation requirements, the nozzle moving speed for excavation cutting is determined to be Amm / s, and the designed cutting depth is Bmm.

[0047] S2, dividing the tunnel face into regions to obtain a plurality of working regions; the jet ejected from the nozzle of the jet cutting equipment moves along a preset contour line of the working region to cut the rock mass to form a cutting contour line.

[0048] When determining the contour range, the entire section needs to be divided into regions based on the surrounding rock characteristics, the jet cutting equipment and the size relationship of the working face, so as to divide the complex face into several easy-to-manage and operate working areas to improve construction efficiency and safety.

[0049] Based on surrounding rock characteristics: First, evaluate the surrounding rock stability, hardness, joint development and other characteristics of each area of ​​the tunnel face. Based on these characteristics, divide the tunnel face into different working areas to ensure that the construction difficulty and safety of each area are similar.

[0050] Consider the size of the equipment: Divide the work area appropriately based on the size, range of motion, and cutting capacity of the jet cutting equipment to ensure that the equipment can cover the entire face and operate effectively.

[0051] Working surface size: Combined with the design dimensions of the tunnel or cavern, determine the size and shape of each working area to maintain the accuracy and continuity of the overall contour during the cutting process.

[0052] Use laser, paint or other marking methods on the tunnel face to clearly mark the preset contour lines, provide clear guidance for the jet cutting equipment, and ensure that the rock contour after cutting meets the design requirements.

[0053] If conditions permit and efficiency is higher, full-face excavation can be considered. This method requires the jet cutting equipment to have sufficient cutting capacity and coverage to complete the cutting operation of the entire tunnel face at one time. In full-face excavation, it is necessary to more accurately control the cutting parameters and equipment status to ensure the accuracy of the cutting contour and the safety of the overall construction.

[0054] S3, cutting and peeling off the rock blocks in the working area layer by layer from top to bottom. The cutting and peeling off of a single rock block includes: the nozzle first cuts along a preset horizontal path below the rock block in an oblique upward cutting manner to obtain an oblique upward cutting surface; then the nozzle cuts along a preset horizontal path above the rock block in an oblique downward cutting manner to obtain an oblique downward cutting surface; the oblique upward cutting surface intersects with the oblique downward cutting surface, so that the rock block peels off and leaves the working area.

[0055] In the process of tunneling or rock mining, the method of cutting and peeling off the rock blocks in the working area layer by layer from top to bottom can significantly improve construction efficiency and safety. This method is combined with jet cutting equipment to achieve effective peeling of the rock mass by precisely controlling the movement path and cutting angle of the nozzle. The following are the detailed steps of the process:

[0056] 1. Determine the cutting levels: First, the entire tunnel face is divided into several cutting levels according to the rock mass characteristics and design requirements of the working area. These levels are usually arranged from top to bottom to ensure stability and safety during construction.

[0057] 2. Cutting and peeling of single rock blocks

[0058] For each individual rock block in each cutting level, the following steps are used for cutting and peeling:

[0059] a. Cutting diagonally upward

[0060] Nozzle Positioning: Position the nozzle of the jet cutting equipment at the starting point of the preset horizontal path under the rock block.

[0061] Cutting operation: Start the jet cutting equipment and move the nozzle along the preset horizontal path in an oblique upward manner to cut the rock. During this process, the high-pressure impact force of the jet will gradually peel off the rock material and form an oblique upward cutting surface.

[0062] Cutting surface control: Ensure that the angle and depth of the oblique upward cutting surface meet the design requirements so that the rock blocks can be peeled off smoothly in the subsequent steps.

[0063] b. Cutting down diagonally

[0064] Nozzle movement: After completing the diagonal upward cut, move the nozzle to the starting point of the preset horizontal path above the rock block.

[0065] Cutting operation: The jet cutting equipment is also started, but this time the nozzle moves along the preset horizontal path in an oblique downward manner to cut the rock mass for the second time. During this process, the jet will form an oblique downward cutting surface that intersects with the previous oblique upward cutting surface.

[0066] Intersection point control: By precisely controlling the moving path and cutting angle of the nozzle, the upward and downward cutting surfaces are ensured to intersect at a predetermined position. At the intersection point, the rock block will be completely cut off and lose its connection with the surrounding rock mass.

[0067] c. Rock spalling

[0068] Gravity effect: After the upward and downward cutting surfaces intersect, the cut rock blocks begin to peel off under the action of gravity.

[0069] Auxiliary stripping: If the rock block fails to peel off immediately for some reason, auxiliary tools (such as robotic arms, vibrators, etc.) can be used to gently knock or vibrate the rock block to help it escape from the work area.

[0070] 3. Repeat the operation: Cut and peel off all the rocks in the working area one by one according to the above steps. During the whole process, it is necessary to continuously monitor the cutting effect and equipment status to ensure the safety and efficiency of the construction.

[0071] 4. Cleaning and inspection: After cutting and peeling, clean up the debris and residue in the working area in time. At the same time, check the cutting surface to ensure that the cutting quality meets the design requirements. If necessary, trim the uneven or non-compliant cutting surface.

[0072] This method can achieve accurate cutting and peeling of the rock mass in the working area, improving construction efficiency and project quality. At the same time, due to the non-contact operation characteristics of the jet cutting equipment, it can also reduce dust and noise pollution during the construction process and improve the construction environment.

[0073] Moreover, this method makes full use of the cutting capability of the jet cutting equipment, without repeated cutting paths. Starting from the third round of cutting, the cut rocks are all in the shape of rectangular strips, and the width of the cross-section of the rectangular strip rock blocks is the designed cutting depth, ensuring the shortest cutting path and the largest rock size, thereby improving the tunneling and excavation efficiency.

[0074] The specific rock cutting of the present invention follows the principle of first down and then up, which avoids falling rocks hitting the nozzle and the jet cutting equipment, and only uses a straight nozzle for cutting, ensuring intuitive and accurate control of the cutting capacity and cutting effect.

[0075] The cutting path of the present invention is simple in design and has stronger environmental adaptability. It can be designed for regional excavation and cutting in large-section tunnels with low surrounding rock grade or where the equipment working height is limited and full-section excavation cannot be performed, thereby expanding the application scenario range of jet cutting.

[0076] In a preferred embodiment, the preset contour lines of the working area in S2 include an actual contour line on the outer edge of the tunnel face and a plurality of separation contour lines located within the tunnel face.

[0077] Preferably, the determination of the actual contour line of the outer edge of the tunnel face includes:

[0078] 1. Determine and solve the mapping function of the tunnel: Where ω(ζ) is the mapping function; k is a positive integer; C k is the real coefficient of the kth term related to the tunnel section size, ζ is the conformal mapping plane, and the coordinates of the point on the ζ plane ζ=ξ+iη=ρe iθ , ξ is the vertical axis, η is the horizontal axis, i is the imaginary unit, ρ is the radius of the unit circle, and θ is the angle between the ξ axis and the line connecting a point on the unit circle and the origin of the coordinate system.

[0079] The mapping function of the composite lining tunnel is solved by the following steps:

[0080] 1) Divide the unit circle and the inner boundary of the surrounding rock into T (integer multiples of 360) parts at equal angles, and obtain T groups of corresponding points according to the angles. The arch vertex (r1, 0) of the inner boundary of the surrounding rock corresponds to the polar coordinate point (1, 0) on the unit circle. Substitute the corresponding points into the mapping function of the tunnel and solve the unknown coefficient C in the formula by the least squares method. k The value of is obtained to obtain the initial expression of the mapping function. Substitute the points on the unit circle into the initial expression of the mapping function to obtain the corresponding T initial mapping points and the inner boundary of the surrounding rock.

[0081] 2) Calculate the ratio of the distance between each two adjacent points on the initial mapping boundary of the inner boundary of the surrounding rock to the distance of the perimeter of the initial mapping boundary h k (k=1,2,3,…,T), adjust the positions of the initial T points on the inner boundary of the real surrounding rock according to the distance ratio. The position of the arch vertex (r1,0) remains unchanged, and adjust the distance between the second point and the arch vertex so that the ratio of the distance to the perimeter of the inner boundary of the real surrounding rock is equal to h1. According to the distance ratio, adjust the positions of the next T-2 points in turn.

[0082] 3) A new correspondence is formed between the points on the adjusted inner boundary of the real surrounding rock and the points on the unit circle to obtain T groups of corresponding points. The corresponding points are substituted into the mapping function of the tunnel to obtain a new mapping function and a new mapping boundary.

[0083] 4) Repeat steps 1), 2) and 3), iterate in a loop, and continuously adjust the position of the points on the inner boundary of the real surrounding rock to obtain a new mapping function. After 15 iterations, the required accuracy can be achieved, thereby obtaining the final mapping function expression.

[0084] 2. Based on the calculation formula The displacement component u of the inner boundary of the surrounding rock is calculated ρ and u θ , where G is the shear elastic modulus, к = 3-4μ, μ is the Poisson's ratio of the surrounding rock, and ψ(ζ) are analytical functions of stress in unsupported tunnel;

[0085]

[0086] Where P is the pressure on the tunnel model at infinity, λ is the lateral pressure coefficient, σ = ζ, S k is the real coefficient of the kth term, a j is the real coefficient of the jth term, is the stress analytical function outside the unit circle on the ζ plane.

[0087] It should be noted that the upper horizontal line “—” in the calculation formula represents conjugation, and the superscript “′” represents the first-order derivative.

[0088] 3. Based on the design contour of the surrounding rock face and the displacement component u of the inner boundary of the surrounding rock ρ and u θ Determine the actual contour line of the outer edge of the tunnel face, that is, use the calculated displacement component u ρ and u θ As a safety margin, it prevents over-excavation or under-excavation caused by changes in the surrounding rock after cutting, ensuring that the actual contour line of the outer edge of the face is consistent with the designed contour line of the surrounding rock face.

[0089] Preferably, the separation contour line in the tunnel face is comprehensively determined according to the surrounding rock characteristics, the jet cutting equipment and the size of the tunnel face.

[0090] For example, see Figure 6 As shown, the tunnel face 1 is divided into two left and right working areas. Accordingly, the preset contour line 2 includes an actual contour line 21 on the outer edge of the tunnel face and a separation contour line 22 located inside the tunnel face. The tunnel face 1 is separated from the surrounding rock by the actual contour line 21 on the outer edge of the tunnel face, and the tunnel face 1 is divided into two left and right working areas by a vertically arranged separation contour line 22.

[0091] Alternatively, see Figure 7 As shown, the tunnel face 1 is divided into two upper and lower working areas. Accordingly, the preset contour line 2 includes an actual contour line 21 on the outer edge of the tunnel face and a separation contour line 22 located inside the tunnel face. The tunnel face 1 is separated from the surrounding rock by the actual contour line 21 on the outer edge of the tunnel face, and the tunnel face 1 is divided into two upper and lower working areas by a transversely arranged separation contour line 22.

[0092] In a preferred embodiment, see Figure 8As shown, the designed cutting depth B1 of the oblique downward cutting surface satisfies 0.8B≤B1≤0.9B, where B is the designed cutting depth of the oblique upward cutting surface. That is, when cutting obliquely downward, it is not necessary to cut to the depth B, and peeling is performed by the robotic arm. With this arrangement, on the one hand, since the cutting depth B1 is less than B, the nozzle movement speed can be accelerated compared to the oblique upward cutting, and the cutting efficiency can be improved. On the other hand, it avoids the rock blocks from falling directly when cutting obliquely downward, thereby improving safety.

[0093] In a preferred embodiment, when the nozzle cuts obliquely upward or obliquely downward, the incident angle between the jet ejected by the nozzle and the tunnel face is 30-60°.

[0094] Such a setting can ensure cutting efficiency and cutting quality on the one hand. When the incident angle is within this range, the jet can more effectively impact and peel off the rock material. If the incident angle is set too small, the jet may not be able to fully penetrate the rock; and if the incident angle is set too large, the jet energy may be dispersed on the rock surface, reducing the cutting efficiency. An appropriate incident angle can help form a smooth and uniform cutting surface. An incident angle that is too large or too small may cause an uneven cutting surface, or even cracks or collapse. On the other hand, it can ensure safety. Operating within this range of incident angles can reduce wear on the nozzle and jet cutting equipment. When the incident angle is too large, the jet may directly impact the nozzle itself or other parts of the equipment, causing damage. By controlling the incident angle within a reasonable range, safety during the construction process can also be improved. An incident angle that is too large may increase the risk of jet rebound and pose a threat to operators.

[0095] Therefore, in actual operation, it is necessary to accurately adjust the incident angle of the nozzle according to the nature of the rock mass, the performance of the cutting equipment and the construction requirements. This usually requires testing and on-site debugging to determine the optimal angle.

[0096] In addition, it should be noted that during the cutting process, the nozzle movement speed and the jet pressure are also important factors affecting the cutting effect. They need to be matched with the incident angle to achieve the best cutting effect.

[0097] Preferably, see Figure 4 As shown, when the nozzle cuts obliquely upward or obliquely downward, the incident angle between the jet ejected by the nozzle and the tunnel face is 45°.

[0098] In a preferred embodiment, see Figure 4 and Figure 5 As shown, the cutting depth D of the cutting contour line satisfies 1.4B≤D≤1.6B, where B is the designed cutting depth of the oblique upward cutting surface. By reasonably designing the cutting depth D of the cutting contour line, it is ensured that the tunnel face area surrounded by the cutting contour line is cut and separated from the surrounding rock, thereby achieving normal spalling of rock blocks in the subsequent working area.

[0099] In order to achieve the required cutting depth D, the nozzle traverse speed can be reduced or reciprocating cutting can be performed when cutting the face contour line.

[0100] The following are some examples:

[0101] S1, determine the nozzle moving speed and cutting depth under the current lithology characteristics and ground stress, such as Figure 2 and Figure 3 As shown, the tunnel face 1 to be cut is leveled, and in the working area, the jet cutting equipment is used to conduct cutting tests on the tunnel face 1 at different nozzle moving speeds to obtain the relationship between the nozzle moving speed and the cutting depth, and the cutting depth at different nozzle moving speeds is obtained. According to the actual tunnel excavation requirements, the nozzle moving speed for excavation cutting is determined to be Amm / s, and the designed cutting depth is Bmm.

[0102] S2, the tunnel face is excavated using the full-face method, and the jet ejected by the nozzle 3 of the jet cutting equipment moves along the actual contour line outside the tunnel face to cut the rock mass to form a cutting contour line.

[0103] S3, cut and peel off the rock blocks in the working area layer by layer from top to bottom, and design the first round of face cutting path according to the cross-sectional size of the face and the cutting depth B. Figure 4 As shown, the nozzle 3 moves horizontally from the surrounding rock wall and cuts along the designed path, so that the rock blocks 4 cut by the first round of the tunnel face are in the shape of long wedges and fall one by one from top to bottom, completing the first round of tunnel face cutting. The cut section 5 obtained after the first round of tunnel face cutting is in a serrated shape, and the fallen rocks are cleaned up.

[0104] The cutting and peeling of a single rock block 4 includes: the nozzle first cuts along a preset horizontal path below the rock block in an oblique upward cutting manner to obtain an oblique upward cutting surface; then the nozzle cuts along a preset horizontal path above the rock block in an oblique downward cutting manner to obtain an oblique downward cutting surface; the oblique upward cutting surface intersects with the oblique downward cutting surface, so that the rock block 4 peels off and leaves the tunnel face 1. When the nozzle cuts obliquely upward or obliquely downward, the incident angle between the jet ejected by the nozzle and the tunnel face is 45°.

[0105] Design the second round of face cutting path according to the cutting depth B, such as Figure 5 As shown, the cutting method is the same as the first round of face cutting, so that the topmost rock is in the shape of a long wedge, and the middle rock is in the shape of a strip and falls one by one from top to bottom, completing the second round of face cutting. The cutting section morphology is as follows Figure 5 as shown, and clearing of fallen rocks.

[0106] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A tunneling face excavation method based on jet cutting, characterized in that: The steps include: S1, in the working area, the cutting test of the tunnel face is carried out using the jet cutting equipment at different nozzle moving speeds to obtain the cutting depth at different nozzle moving speeds; S2, dividing the tunnel face into regions to obtain a plurality of working regions; the jet ejected from the nozzle of the jet cutting equipment moves along the preset contour line of the working region to cut the rock mass to form a cutting contour line; the preset contour line of the working region includes the actual contour line of the outer edge of the tunnel face and a plurality of separation contour lines located within the tunnel face; The determination of the actual contour line of the outer edge of the tunnel face includes: Determine and solve the mapping function of the tunnel: Where ω(ζ) is the mapping function; k is a positive integer; C k is the real coefficient of the kth term related to the tunnel section size, ζ is the conformal mapping plane, and the coordinates of the point on the ζ plane ζ=ξ+iη=ρe iθ , ξ is the vertical axis, η is the horizontal axis, i is the imaginary unit, ρ is the radius of the unit circle, and θ is the angle between the line connecting a point on the unit circle and the origin of the coordinate system and the ξ axis; According to the calculation formula The displacement component u of the inner boundary of the surrounding rock is calculated ρ and u θ , where G is the shear elastic modulus, к = 3-4μ, μ is the Poisson's ratio of the surrounding rock, and ψ(ζ) are analytical functions of stress in unsupported tunnel; Where P is the pressure on the tunnel model at infinity, λ is the lateral pressure coefficient, σ = ζ, S k is the real coefficient of the kth term, a j is the real coefficient of the jth term, is the stress analytical function of the outer domain of the unit circle on the ζ plane; Based on the design contour of the surrounding rock face and the displacement component u of the inner boundary of the surrounding rock ρ and u θ Determine the actual contour line of the outer edge of the tunnel face; S3, cutting and peeling off the rock blocks in the working area layer by layer from top to bottom. The cutting and peeling off of a single rock block includes: the nozzle first cuts along a preset horizontal path below the rock block in an oblique upward cutting manner to obtain an oblique upward cutting surface; then the nozzle cuts along a preset horizontal path above the rock block in an oblique downward cutting manner to obtain an oblique downward cutting surface; the oblique upward cutting surface intersects with the oblique downward cutting surface, so that the rock block peels off and leaves the working area.

2. The tunneling face excavation method based on jet cutting according to claim 1 is characterized in that: The designed cutting depth B1 of the oblique downward cutting surface satisfies 0.8B≤B1≤0.9B, where B is the designed cutting depth of the oblique upward cutting surface.

3. The tunneling face excavation method based on jet cutting according to claim 1 is characterized in that: The separation contour line in the tunnel face is comprehensively determined according to the surrounding rock characteristics, the jet cutting equipment and the size of the tunnel face.

4. The tunneling face excavation method based on jet cutting according to claim 1 is characterized in that: When the nozzle cuts obliquely upward or obliquely downward, the incident angle between the jet ejected by the nozzle and the tunnel face is 30 to 60 degrees.

5. The tunneling face excavation method based on jet cutting according to claim 1, characterized in that: When the nozzle cuts obliquely upward or obliquely downward, the incident angle between the jet ejected by the nozzle and the tunnel face is 45°.

6. The tunneling face excavation method based on jet cutting according to claim 1, characterized in that: The cutting depth D of the cutting contour line satisfies 1.4B≤D≤1.6B, where B is the designed cutting depth of the oblique upward cutting surface.

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