Design method and structure of a U-shaped shell reinforced shield tunnel structure

Abstract

The present invention relates to the technical field of shield tunnel reinforcement structure design, and in particular to a design method and structure of a U-shaped shell reinforced shield tunnel structure. The present invention obtains stress parameters of a soil layer and determines a soil point cloud by a pulse ranging method, and calculates the position and posture of the soil point cloud in combination with an optimized iterative method, so as to form an accurate point cloud distribution map in a tunnel model. According to the calculated soil point cloud data and stress grid map, different anchoring methods and anchor sizes can be set for areas with different soil layers and looseness. Based on the stress grid map and reinforcement strategy, a U-shaped shell that meets actual needs can be designed. The customized design can improve the bearing capacity and stability of the U-shaped shell, thereby better meeting the reinforcement needs of the tunnel structure.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnel reinforcement structure design, in particular to a design method and structure of a U-shaped shell reinforced shield tunnel structure. Background Art

[0002] With the acceleration of urbanization, underground space development has become an important means to ease urban ground traffic pressure and optimize urban space layout. As an important form of underground transportation construction, shield tunnels are widely used in subways, municipal pipe corridors and other projects due to their advantages such as fast construction speed and little impact on the ground environment.

[0003] A Chinese patent application with publication number CN117852144A discloses a method for designing a lining structure of a composite reinforced shield tunnel based on a failure mode. The method is based on the failure mechanism of a full-ring experiment of a composite reinforced shield tunnel, envelops and considers the stress development history of the shield tunnel segment, and based on the stress development of different sections, calculates the height of the compression zone of the section and the strain variable of the concrete in the compression zone under the incremental load, solves the section strain and section stress distribution under the specific incremental load, and solves the problem that the stress history of the in-service shield tunnel cannot be measured; by iterative calculation, the sign of the section bending moment and the sign of the stiffness are matched, and the problem of different stiffness of the asymmetric section of the superimposed shield tunnel under the action of positive and negative bending moments is solved; by three-dimensional laser scanning, the initial deformation of the shield tunnel before reinforcement is obtained, and the initial deformation is taken into account in the calculation of the bearing capacity and stiffness of the composite reinforced shield tunnel.

[0004] However, the patent has the following defects: the bearing capacity and stiffness of the shield tunnel are obtained through calculation, but no measures are taken to directly enhance the local or overall strength of the tunnel lining. Summary of the invention

[0005] In view of the above problems in the prior art, the present invention is proposed.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a design method of a U-shaped shell reinforced shield tunnel structure, which comprises step S1: using a scanning device to scan the rock and soil layer inside the shield tunnel to obtain soil layer data;

[0007] Step S2: import soil layer data and form a tunnel model, obtain stress parameters of the soil layer based on the pulse ranging method and determine the soil point cloud, calculate the position of the soil point cloud by optimizing and iterating the obtained soil point cloud, form a point cloud distribution map on the tunnel model, and construct a stress grid map based on the point cloud distribution map;

[0008] Step S3: determining the stress mutation position based on the stress grid diagram, determining the reinforcement strategy according to the mutation position and soil layer data, and determining the anchor point position and anchor type based on the reinforcement strategy;

[0009] Step S4: Design the U-shaped shell according to the stress grid diagram and reinforcement strategy.

[0010] As a preferred solution of the design method of the U-shaped shell reinforced shield tunnel structure of the present invention, wherein: Step S1.1: measuring the vault height and depth of the tunnel, setting the field of view angle, and setting the speed of controlling the scanning movement of the three-dimensional laser scanner;

[0011] Step S1.2: Obtain the latitude and longitude information of the target tunnel, and obtain the properties of the surrounding rock and soil layers, and set the laser emission frequency and pulse width according to the properties of the rock and soil layers;

[0012] Step S1.3: Obtain the pulse signal obtained by the three-dimensional laser scanner to obtain soil layer data, and construct a simulation model for simulating the tunnel rock and soil layer according to the pulse signal. The simulation model is used to simulate different rock and soil layers represented by the soil layer data and the looseness of the rock and soil layers.

[0013] As a preferred solution of the design method of the U-shaped shell reinforced shield tunnel structure of the present invention, step S1.3 includes:

[0014] Step S1.3.1: The calculation formula used to simulate the looseness of the rock and soil layers in the tunnel is expressed as:

[0015]

[0016] in: Indicates the looseness of the simulated tunnel rock and soil layer. It represents the processing and analysis of the pulse signal obtained from the 3D laser scanner. is the speed at which the 3D laser scanner moves. is the angle of the on-site scan, is the laser emission frequency, is the pulse width;

[0017] L is the length of the tunnel, n is the number of geotechnical layers, is a natural constant, , , , is the coefficient of the scanned data, x is the location coordinate of the tunnel;

[0018] Step S1.3.2: Set the normalization function to extract the image display range from the simulation model:

[0019]

[0020] in: represents the normalized output value, M is the original input value, and are the minimum and maximum values ​​of the simulation model, respectively. The range of the simulation model is mapped to the range of [0,1] through the normalization function for image display. The range is [0,1], where 0 represents a loose rock and soil layer and 1 represents a tight rock and soil layer;

[0021] Step S1.3.3: The simulation model used to simulate the three-dimensional structure of the tunnel is expressed as:

[0022]

[0023] The simulation model is used to simulate the three-dimensional structure of the tunnel in the three-dimensional software, and the different rock and soil layers and the looseness of the rock and soil are displayed in the three-dimensional structure.

[0024] As a preferred solution of the design method of the U-shaped shell reinforced shield tunnel structure of the present invention, step S2 comprises:

[0025] Since the pulse signal will be reflected when it encounters the soil surface, the distance can be calculated according to the propagation time difference of the pulse. By collecting the reflection data of multiple pulse signals, the three-dimensional soil point cloud of the soil surface can be obtained;

[0026] Step S2.1: The process of obtaining soil point cloud by pulse ranging method is described by constructing a mathematical formula. The pulse ranging method obtains the initial pose matrix R of soil point cloud, where each element It is calculated by the following formula:

[0027] =( , , , 1)

[0028] in, Indicates The pose vector of each point, ( , , ) is The three-dimensional coordinates of a point, 1 means the point exists;

[0029] The optimization iterative process is performed by minimizing the objective function To adjust the pose matrix R:

[0030]

[0031] Among them, R represents the pose matrix of all points, which is composed of all Composition, T represents the transformation matrix in the optimization iteration process, which is used to adjust the posture. is the objective function used to evaluate the accuracy of the pose, which is the sum of the squares of the distances from all points to the reference point, that is:

[0032] = ;

[0033] Where N is the number of points in the soil point cloud, It is The distance from the point to the reference point is measured by pulse ranging method. represents the Euclidean norm.

[0034] As a preferred solution of the design method of the U-shaped shell reinforced shield tunnel structure of the present invention, wherein: the position and posture of the soil point cloud are obtained by optimizing iteration through the gradient descent method;

[0035] Step S2.2: Update the pose matrix R and transformation matrix T using the gradient descent method:

[0036] f(R, T)

[0037] f(R, T)

[0038] in, Represents the learning rate, which is used to control the speed of optimization iteration. f(R, T) and f(R, T) are the gradients of the pose matrix R and the transformation matrix T respectively;

[0039] Finally, the obtained pose matrix R is the pose of the optimized soil point cloud.

[0040] As a preferred solution of the design method of the U-shaped shell reinforced shield tunnel structure of the present invention, wherein: a stress grid diagram is formed according to the calculated soil point cloud data;

[0041] Combined with the stress grid diagram, the mutation surface area is determined for different soil layers and different looseness levels. The determination method of the mutation surface area includes:

[0042] Set a domain threshold, divide the stress grid map by the domain threshold, identify the basic rock layer and basic stress in the stress grid map, the basic rock layer represents the main geotechnical structure of the shield tunnel, identify the area in the stress grid map that is different from the basic rock layer and mark it as a stress mutation position, and mark the domain of the stress mutation position in the stress grid map as a mutation domain;

[0043] Compare the mutation face domain with the face domain threshold and set the reinforcement strategy;

[0044] The reinforcement strategy includes high-density logic and standard-strength logic. If the area of ​​the mutation domain is greater than the domain threshold, the high-density logic is executed. If the area of ​​the mutation domain is less than the domain threshold, the standard-strength logic is executed.

[0045] As a preferred solution of the design method of the U-shaped shell reinforced shield tunnel structure of the present invention, the high-density logic specifically includes:

[0046] Obtain the edge of the mutation surface area, obtain the area of ​​the mutation surface area, extract the centroid position of the mutation surface area, set a standard anchoring frame with the centroid position of the mutation surface area as the midpoint, and form anchoring point marks at the corner points of the anchoring frame;

[0047] The mutation amplitude of the mutation surface domain is calculated, and the number of anchor points to be anchored is determined based on the mutation amplitude. The mutation amplitude expression is:

[0048]

[0049] in, Represents the standard surface area, represents the maximum area of ​​the mutation domain, Indicates the maximum area of ​​the standard domain;

[0050] The expression for the number of anchor points is:

[0051]

[0052] Where Z is the number of anchor points, A is the first ratio threshold, B is the second ratio threshold, and Z 1 , Z 2 , Z 3 It represents the installation quantity standards of different anchor point markers determined under different thresholds of mutation amplitude.

[0053] As a preferred solution of the design method of the U-shaped shell reinforced shield tunnel structure of the present invention, wherein:

[0054] The high-density logic also includes:

[0055] Get the extreme distance from the corner point of the anchoring frame to the mutation surface, extract the middle position of the extreme distance, set the anchor point mark at the middle position of the extreme distance, and determine whether the number of anchor point marks meets the calculated number of anchor point marks:

[0056] set up is the number of anchor points actually set. is the number of anchor points obtained by calculation, when > When , the random supplement quantity is - The number of anchor points;

[0057] when ≤ When is the number of final anchor points.

[0058] As a preferred solution of the design method of the U-shaped shell reinforced shield tunnel structure of the present invention, wherein:

[0059] The standard logic specifically includes:

[0060] Set the fixed border based on the anchor border, and set the anchor points at the corners of the fixed border. The expression of the fixed border is:

[0061]

[0062] in, , is the area of ​​the solid frame, is the area of ​​the anchor border.

[0063] A U-shaped shell reinforced shield tunnel structure is applied to a design method of a U-shaped shell reinforced shield tunnel structure, which includes: a tunnel segment fixed to the inner wall of the shield tunnel, a fixing groove is opened on the outer wall of the tunnel segment and a socket joint is screwed to the inner wall of the fixing groove, a fixing head is screwed to the outer wall of the tunnel segment, a hand hole is opened on the inner wall of the tunnel segment and a chemical anchor bolt is screwed to the inner wall of the tunnel segment.

[0064] As a preferred solution of the U-shaped shell reinforced shield tunnel structure described in the present invention, the inner wall of the tunnel segment is provided with a U-shaped shell, the end of the U-shaped shell is provided with a variable cross-section, the end of the U-shaped shell is also provided with an installation groove, the outside of the installation groove is provided with a reinforcement plate, the inner wall of the tunnel segment is also provided with a ballast, and the outer wall of the ballast is provided with a bracket.

[0065] Beneficial effects of the present invention: The present invention obtains the stress parameters of the soil layer and determines the soil point cloud through the pulse ranging method, and calculates the position and posture of the soil point cloud in combination with the optimization iteration method, so as to form an accurate point cloud distribution map in the tunnel model. According to the calculated soil point cloud data and stress grid map, different anchoring methods and anchor sizes can be set for areas with different soil layers and looseness. Based on the stress grid map and reinforcement strategy, a U-shaped shell that meets actual needs can be designed. The customized design can improve the bearing capacity and stability of the U-shaped shell, thereby better meeting the reinforcement requirements of the tunnel structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0067] Figure 1 A flow chart of a design method for a U-shaped shell reinforced shield tunnel structure according to the present invention;

[0068] Figure 2 A flow chart of measuring tunnel data and forming a tunnel rock and soil layer model in the present invention;

[0069] Figure 3 It is a flow chart of the output pose matrix in the present invention;

[0070] Figure 4 A flow chart for determining and generating an anchoring method in the present invention;

[0071] Figure 5 It is a schematic diagram of the surface domain threshold and the stress grid diagram in the present invention;

[0072] Figure 6 It is an overall schematic diagram of the U-shaped shell reinforced shield tunnel structure in the present invention;

[0073] Figure 7 It is a schematic diagram of the installation of the tunnel segment and the U-shaped shell in the present invention;

[0074] Figure 8 is a side cross-sectional view of a tunnel segment in the present invention;

[0075] Fig. 9 It is a schematic diagram of the connection relationship of the U-shaped shell in the present invention;

[0076] Fig.10 It is a schematic diagram of the installation of the reinforcing plate in the present invention;

[0077] Fig.11 It is a cross-sectional view of the U-shaped shell and the reinforcing plate in the present invention.

[0078] Figure numerals: 101, tunnel segment; 102, fixing groove; 103, socket; 104, fixing head; 105, hand hole; 106, chemical anchor; 201, U-shaped shell; 202, variable section; 203, installation groove; 204, reinforcement plate; 301, roadbed; 302, bracket. DETAILED DESCRIPTION

[0079] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0080] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0081] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0082] Example 1

[0083] Reference Figure 1~Figure 5 , which is the first embodiment of the present invention, provides a design method for a U-shaped shell reinforced shield tunnel structure, comprising:

[0084] Step S1: Scan the rock and soil layer inside the shield tunnel using a scanning device to obtain soil layer data;

[0085] Step S2: import soil layer data and form a tunnel model, obtain stress parameters of the soil layer based on the pulse ranging method and determine the soil point cloud, calculate the position of the soil point cloud by optimizing and iterating the obtained soil point cloud, form a point cloud distribution map on the tunnel model, and construct a stress grid map based on the point cloud distribution map;

[0086] Step S3: determining the stress mutation position based on the stress grid diagram, determining the reinforcement strategy according to the mutation position and soil layer data, and determining the anchor point position and anchor type based on the reinforcement strategy;

[0087] Step S4: Design the U-shaped shell according to the stress grid diagram and reinforcement strategy.

[0088] The specific steps of step S1 include:

[0089] Step S1.1: measuring the vault height and depth of the tunnel, setting the field of view angle, and setting the speed of controlling the scanning movement of the 3D laser scanner;

[0090] Step S1.2: Obtain the latitude and longitude information of the target tunnel, and obtain the properties of the surrounding rock and soil layers, and set the laser emission frequency and pulse width according to the properties of the rock and soil layers;

[0091] Step S1.3: Obtain the pulse signal obtained by the three-dimensional laser scanner to obtain soil layer data, and construct a simulation model for simulating the tunnel rock and soil layer according to the pulse signal. The simulation model is used to simulate different rock and soil layers represented by the soil layer data and the looseness of the rock and soil layers.

[0092] Step S1.3 includes:

[0093] Step S1.3.1: The calculation formula used to simulate the looseness of the rock and soil layers in the tunnel is expressed as:

[0094]

[0095] in: Indicates the looseness of the simulated tunnel rock and soil layer. It represents the processing and analysis of the pulse signal obtained from the 3D laser scanner. is the speed at which the 3D laser scanner moves. is the angle of the on-site scan, is the laser emission frequency, is the pulse width;

[0096] L is the length of the tunnel, n is the number of geotechnical layers, is a natural constant, , , , is the coefficient of the scanned data, x is the location coordinate of the tunnel;

[0097] Step S1.3.2: Set the normalization function to extract the image display range from the simulation model:

[0098]

[0099] in: represents the normalized output value, M is the original input value, and are the minimum and maximum values ​​of the simulation model, respectively. The range of the simulation model is mapped to the range of [0,1] through the normalization function for image display. The range is [0,1], where 0 represents a loose rock and soil layer and 1 represents a tight rock and soil layer;

[0100] Step S1.3.3: The simulation model used to simulate the three-dimensional structure of the tunnel is expressed as:

[0101]

[0102] The simulation model is used to simulate the three-dimensional structure of the tunnel in the three-dimensional software, and the different rock and soil layers and the looseness of the rock and soil are displayed in the three-dimensional structure.

[0103] Step S2 includes:

[0104] Since the pulse signal will be reflected when it encounters the soil surface, the distance can be calculated according to the propagation time difference of the pulse. By collecting the reflection data of multiple pulse signals, the three-dimensional soil point cloud of the soil surface can be obtained;

[0105] Step S2.1: The process of obtaining soil point cloud by pulse ranging method is described by constructing a mathematical formula. The pulse ranging method obtains the initial pose matrix R of soil point cloud, where each element It is calculated by the following formula:

[0106] =( , , , 1)

[0107] in, Indicates The pose vector of each point, ( , , ) is The three-dimensional coordinates of a point, 1 means the point exists;

[0108] The optimization iterative process is performed by minimizing the objective function To adjust the pose matrix R:

[0109]

[0110] Among them, R represents the pose matrix of all points, which is composed of all Composition, T represents the transformation matrix in the optimization iteration process, which is used to adjust the posture. Is the objective function used to evaluate the accuracy of the pose, which can be the sum of the squares of the distances from all points to the reference point, that is:

[0111] = ;

[0112] Where N is the number of points in the soil point cloud, It is The distance from the point to the reference point is measured by pulse ranging method. represents the Euclidean norm.

[0113] The pose of the soil point cloud is obtained by optimizing iteration through the gradient descent method;

[0114] Step S2.2: Update the pose matrix R and transformation matrix T using the gradient descent method:

[0115] f(R, T)

[0116] f(R, T)

[0117] in, Represents the learning rate, which is used to control the speed of optimization iteration. f(R, T) and f(R, T) are the gradients of the pose matrix R and the transformation matrix T respectively;

[0118] Finally, the obtained pose matrix R is the pose of the optimized soil point cloud.

[0119] Example 2

[0120] This is the second embodiment of the present invention, which is implemented based on the previous embodiment.

[0121] A stress grid diagram is formed based on the calculated soil point cloud data.

[0122] Set up a set of logic to combine the stress grid diagram to set the corresponding size specifications of the anchoring method and the size of the anchor for different soil layers and different looseness levels;

[0123] Set the domain threshold, divide the stress grid map by the domain threshold, identify the basic rock layer and basic stress in the stress grid map, the basic rock layer represents the main geotechnical structure of the shield tunnel, identify the area in the stress grid map that is different from the basic rock layer and mark it as the stress mutation location, such as Figure 5 As shown, the shaded part in the figure represents the area where stress mutation occurs in the stress grid diagram, and the surface area where the stress mutation occurs in the stress grid diagram is marked as the mutation surface area. The mutation surface area is compared with the surface area threshold, and the reinforcement strategy is set;

[0124] The reinforcement strategy includes high-density logic and standard-strength logic. If the area of ​​the mutation domain is greater than the domain threshold, the high-density logic is executed. If the area of ​​the mutation domain is less than the domain threshold, the standard-strength logic is executed.

[0125] In combination with the anchoring strategy, describe the specific method of designing the U-shaped shell, specifically the details of the high-density logic / standard anchoring logic;

[0126] High-density logic specifically includes:

[0127] Obtain the edge of the mutation surface area, obtain the area of ​​the mutation surface area, extract the centroid position of the mutation surface area, set a standard anchoring frame, and form anchoring point marks at the corner points of the anchoring frame;

[0128] The mutation amplitude of the mutation surface domain is calculated, and the number of anchor points to be anchored is determined based on the mutation amplitude. The mutation amplitude expression is:

[0129]

[0130] in, Represents the standard surface area, represents the maximum area of ​​the mutation domain, Indicates the maximum area of ​​the standard domain;

[0131] The expression for the number of anchor points is:

[0132]

[0133] Where Z is the number of anchor points, A is the first ratio threshold, B is the second ratio threshold, and Z 1 , Z 2 , Z 3 It indicates the installation quantity standards of different anchor point markers determined under different thresholds of mutation amplitude;

[0134] Further:

[0135] like Figure 5 C in the middle represents the fixed installation position of an anchor point mark in an anchor frame, obtains the extreme distance from the corner point of the anchor frame to the mutation surface domain, extracts the middle position of the extreme distance, sets the anchor point mark at the middle position of the extreme distance, and determines whether the number of anchor point marks meets the calculated number of anchor point marks:

[0136] set up is the number of anchor points actually set. is the number of anchor points obtained by calculation, when > When , the random supplement quantity is - The number of anchor points;

[0137] The supplementary position can be randomly selected and does not overlap with the existing anchor point mark position. The corner point position of the anchor frame is given priority. If all the corner points of the anchor frame have been set with anchor point marks, the middle position of the distance from the corner point of the anchor frame to the extreme value of the mutation surface domain is considered, and finally it is randomly set at the edge position of the mutation surface domain.

[0138] when ≤ When is the number of final anchor points.

[0139] Furthermore, the standard logic specifically includes:

[0140] Set the fixed border based on the anchor border, and set the anchor points at the corners of the fixed border. The expression of the fixed border is:

[0141]

[0142] in, , is the area of ​​the solid frame, is the area of ​​the anchor border.

[0143] The diameter and length of the U-shaped shell are determined based on stress analysis and the actual needs of the tunnel structure. Generally speaking, the larger the diameter and the longer the U-shaped shell, the higher the bearing capacity and the better the stability. Different U-shaped shells and installation methods are designed according to different tunnel structures. In tunnel sections with relatively soft soil, settlement and deformation are prone to occur due to the poor stability of the soil. Therefore, a stronger U-shaped shell is needed to enhance the bearing capacity and stability of the structure.

[0144] When designing these U-shaped shells, high-strength and high-toughness materials, such as steel or carbon fiber composite materials, should be selected to ensure that they are not easily broken or deformed when subjected to large external forces.

[0145] In order to enhance the fixing effect, the bottom of this part of the U-shaped shell needs to be buried to a certain depth underground during installation. This can increase the contact area with the soil, improve the stability and anti-slip ability of the U-shaped shell. At the same time, anchor bolts and other fixing methods can be used to firmly fix the U-shaped shell in the soil.

[0146] In tunnel sections with relatively hard soil, the strength requirements of the U-shaped shell can be appropriately reduced because the soil itself has high stability and bearing capacity.

[0147] These U-shaped shells can be designed using relatively thin materials such as stainless steel or lightweight alloys to reduce cost and weight.

[0148] Since the soil is hard, the U-shaped shell does not need to be inserted deep into the soil, but it still needs to be ensured to fit tightly and be securely fixed to the tunnel surface to prevent loosening or displacement due to external forces.

[0149] In tunnel sections located in geologically variable areas, special attention needs to be paid to the design and installation of the U-shell due to the complexity and uncertainty of the geological conditions.

[0150] When designing these U-shaped shells, full consideration should be given to the possible impact of geological changes, such as earthquakes, landslides and other natural disasters, and materials and structural forms with higher seismic resistance and adaptability can be selected.

[0151] During the installation process, it is necessary to pay close attention to geological changes and adjust the installation position and angle of the U-shaped shell in time. At the same time, a combination of multiple fixing methods can be used, such as anchor bolts, embedded steel bars, etc., to improve the stability and reliability of the U-shaped shell in areas of geological changes.

[0152] In tunnel sections where cracks exist, special measures are required to reinforce the U-shaped shell because the presence of cracks may lead to instability and increased deformation of the tunnel structure.

[0153] When designing these U-shaped shells, materials with higher strength and toughness should be selected, and the impact of cracks on the stress of the U-shaped shell should be considered. Thickening design or setting reinforcement ribs can be used to improve the bearing capacity and crack resistance of the U-shaped shell.

[0154] During the installation process, the cracks need to be filled and sealed to ensure the close integration of the U-shaped shell and the tunnel surface. At the same time, special fixing methods and connectors can be used to enhance the stability and integrity of the U-shaped shell in the cracked area.

[0155] The installation location and laying strategy of the U-shell also takes into account the deformation and settlement of the tunnel structure, ensuring that the reinforced structure can adapt to the long-term deformation and settlement of the tunnel.

[0156] In summary, the U-shaped shell in the tunnel structure design needs to be designed and installed differently according to the geological conditions of different sections. The density of the U-shaped shell arrangement and installation should also be arranged according to the specific conditions of the current tunnel structure. By selecting suitable materials, optimizing the structure and strengthening the fixation, the bearing capacity and stability of the U-shaped shell can be improved to ensure the safety and durability of the tunnel structure.

[0157] The location of the anchor bolts also takes into account the overall stability and long-term durability requirements of the tunnel structure to ensure that the anchor bolts can play an effective role for a long time. The fixing method of the U-shaped shell and the anchor bolt also includes anti-corrosion and anti-rust treatment of the connection parts to improve the durability and service life of the reinforced structure.

[0158] Example 3

[0159] Reference Figure 3~Figure 11 , which is the third embodiment of the present invention, and this embodiment is implemented based on the previous embodiment.

[0160] A U-shaped shell reinforced shield tunnel structure is applied to a design method of a U-shaped shell reinforced shield tunnel structure, specifically, it includes a tunnel segment 101 fixed to the inner wall of the shield tunnel, the outer wall of the tunnel segment 101 is provided with a fixing groove 102 and the inner wall of the fixing groove 102 is also screwed with a socket 103, the outer wall of the tunnel segment 101 is also screwed with a fixing head 104, the inner wall of the tunnel segment 101 is provided with a hand hole 105 and the inner wall of the tunnel segment 101 is also screwed with a chemical anchor bolt 106.

[0161] The segment ring is composed of six tunnel segments 101, which are tightly attached to the inside of the tunnel. The socket joints 103 and fixed heads 104 arranged on both sides of the tunnel segment 101 correspond to each other. The fixed head 104 on the left outer wall can be inserted into the socket joint 103 on the right side of the adjacent tunnel segment 101 to connect the adjacent tunnel segments 101, and then connected and fixed by bolts inside the hand hole 105.

[0162] The chemical anchor bolts 106 are fixed to the inner wall of the tunnel segment 101 in groups of two and are installed in multiple groups in an annular array along the tunnel segment 101 . The tops of the chemical anchor bolts 106 are exposed outside the tunnel segment 101 .

[0163] Reference Figure 6~Figure 11 A U-shaped shell 201 is disposed on the inner wall of the tunnel segment 101 , a variable cross-section 202 is disposed at the end of the U-shaped shell 201 , a placement groove 203 is also opened at the end of the U-shaped shell 201 , and a reinforcement plate 204 is disposed outside the placement groove 203 .

[0164] The U-shaped shell 201 is closely attached to the inner wall of the tunnel segment 101 , and the flanges on both sides are coated with structural adhesive and fixed to the inner wall of the tunnel segment 101 . The top end of the chemical anchor 106 is close to the web of the U-shaped shell 201 .

[0165] Each FRP cavity is composed of three sections of U-shaped shells 201, and the chemical anchor bolts 106 are located inside the cavity. According to actual conditions, two, three or four fixing methods can be selected, and the number of rows of chemical anchor bolts 106 to be fixed corresponds to the number.

[0166] High-strength non-shrinkage grouting material is poured into each FRP cavity through the circulating pouring method, and cracks, peeling and other defects of the pipe segment can be repaired at the same time. The connection between adjacent U-shaped shells 201 is fixed by a reinforcement plate 204 to prevent the U-shaped shell 201 from falling off from the inner wall of the tunnel segment 101 or gaps from appearing when pouring grout, which will affect the effect of subsequent pouring.

[0167] When the slurry solidifies, the U-shaped shell 201 and the chemical anchor bolts 106 are fixed together to form a whole with the tunnel segment 101, thereby enhancing the structural strength of the tunnel segment 101.

[0168] Reference Figure 6 The inner wall of the tunnel segment 101 is also provided with a ballast bed 301 , and the outer wall of the ballast bed 301 is provided with a bracket 302 .

[0169] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A design method for a U-shaped shell reinforced shield tunnel structure, characterized in that: include: Step S1: Scan the rock and soil layer inside the shield tunnel using a scanning device to obtain soil layer data; Step S2: import soil layer data and form a tunnel model, obtain stress parameters of the soil layer based on the pulse ranging method and determine the soil point cloud, calculate the position of the soil point cloud by optimizing and iterating the obtained soil point cloud, form a point cloud distribution map on the tunnel model, and construct a stress grid map based on the point cloud distribution map; Step S3: determining the stress mutation position based on the stress grid diagram, determining the reinforcement strategy according to the mutation position and soil layer data, and determining the anchor point position and anchor type based on the reinforcement strategy; Step S4: designing a U-shaped shell according to the stress grid diagram and reinforcement strategy; The specific steps of step S1 include: Step S1.1: measuring the vault height and depth of the tunnel, setting the field of view angle, and setting the speed of controlling the scanning movement of the 3D laser scanner; Step S1.2: Obtain the latitude and longitude information of the target tunnel, and obtain the properties of the surrounding rock and soil layers, and set the laser emission frequency and pulse width according to the properties of the rock and soil layers; Step S1.3: Obtaining the pulse signal obtained by the three-dimensional laser scanner to obtain soil layer data, and constructing a simulation model for simulating the rock and soil layer of the tunnel according to the pulse signal, wherein the simulation model is used to simulate different rock and soil layers represented by the soil layer data and the looseness of the rock and soil layers; Step S1.3 includes: Step S1.3.1: The calculation formula used to simulate the looseness of the rock and soil layers in the tunnel is expressed as: in: Indicates the looseness of the simulated tunnel rock and soil layer. It represents the processing and analysis of the pulse signal obtained from the 3D laser scanner. is the speed at which the 3D laser scanner moves. is the angle of the on-site scan, is the laser emission frequency, is the pulse width; L is the length of the tunnel, n is the number of geotechnical layers, is a natural constant, , , , is the coefficient of the scanned data, x is the location coordinate of the tunnel; Step S1.3.2: Set the normalization function to extract the image display range from the simulation model: in: represents the normalized output value, M is the original input value, and are the minimum and maximum values ​​of the simulation model, respectively. The range of the simulation model is mapped to the range of [0,1] through the normalization function, where 0 represents a loose rock and soil layer and 1 represents a tight rock and soil layer; Step S1.3.3: The simulation model used to simulate the three-dimensional structure of the tunnel is expressed as: The simulation model is used to simulate the three-dimensional structure of the tunnel in the three-dimensional software, and the different rock and soil layers and the looseness of the rock and soil are displayed in the three-dimensional structure.

2. The design method of the U-shaped shell reinforced shield tunnel structure according to claim 1, characterized in that: Step S2 includes: Step S2.1: The process of obtaining soil point cloud by pulse ranging method is described by constructing a mathematical formula. The pulse ranging method obtains the initial pose matrix R of soil point cloud, where each element It is calculated by the following formula: =（ ， ， ，1） in, Indicates The pose vector of each point, ( , , ) is The three-dimensional coordinates of a point, 1 means the point exists; The optimization iterative process is performed by minimizing the objective function To adjust the pose matrix R: Among them, R represents the pose matrix of all points, which is composed of all Composition, T represents the transformation matrix in the optimization iteration process, which is used to adjust the posture. is the objective function used to evaluate the accuracy of the pose, which is the sum of the squares of the distances from all points to the reference point, that is: = Where N is the number of points in the soil point cloud, It is The distance from the point to the reference point is measured by pulse ranging method. represents the Euclidean norm.

3. The design method of the U-shaped shell reinforced shield tunnel structure according to claim 2, characterized in that: The pose of the soil point cloud is obtained by optimizing iteration through the gradient descent method; Step S2.2: Update the pose matrix R and transformation matrix T using the gradient descent method: f(R,T) f(R,T) in, Represents the learning rate, which is used to control the speed of optimization iteration. f(R, T) and f(R, T) are the gradients of the pose matrix R and the transformation matrix T respectively; Finally, the obtained pose matrix R is the pose of the optimized soil point cloud.

4. The design method of the U-shaped shell reinforced shield tunnel structure according to claim 3, characterized in that: Based on the calculated soil point cloud data, a stress grid diagram is formed; Combined with the stress grid diagram, the mutation surface area is determined for different soil layers and different looseness levels. The determination method of the mutation surface area includes: Set a domain threshold, divide the stress grid map by the domain threshold, identify the basic rock layer and basic stress in the stress grid map, the basic rock layer represents the main geotechnical structure of the shield tunnel, identify the area in the stress grid map that is different from the basic rock layer and mark it as a stress mutation position, and mark the domain of the stress mutation position in the stress grid map as a mutation domain; Compare the mutation face domain with the face domain threshold and set the reinforcement strategy; The reinforcement strategy includes high-density logic and standard-strength logic. If the area of ​​the mutation domain is greater than the domain threshold, the high-density logic is executed. If the area of ​​the mutation domain is less than the domain threshold, the standard-strength logic is executed.

5. The design method of the U-shaped shell reinforced shield tunnel structure according to claim 4, characterized in that: The high-density logic specifically includes: Obtain the edge of the mutation surface area, obtain the area of ​​the mutation surface area, extract the centroid position of the mutation surface area, set a standard anchoring frame with the centroid position of the mutation surface area as the midpoint, and form anchoring point marks at the corner points of the anchoring frame; The mutation amplitude of the mutation surface domain is calculated, and the number of anchor points to be anchored is determined based on the mutation amplitude. The mutation amplitude expression is: in, represents the standard surface area, represents the maximum area of ​​the mutation surface, Indicates the maximum area of ​​the standard domain; The expression for the number of anchor points is: Among them, Z is the number of anchor point markers, A is the first ratio threshold, B is the second ratio threshold, and Z1, Z2, and Z3 represent different anchor point marker installation quantity standards determined under different thresholds for mutation amplitudes.

6. The design method of the U-shaped shell reinforced shield tunnel structure according to claim 5, characterized in that: The high-density logic also includes: Get the extreme distance from the corner point of the anchoring frame to the mutation surface, extract the middle position of the extreme distance, set the anchor point mark at the middle position of the extreme distance, and determine whether the number of anchor point marks meets the calculated number of anchor point marks: set up is the number of anchor points actually set. is the number of anchor points obtained by calculation, when > When , the random supplement quantity is - The number of anchor points; when ≤ When is the number of final anchor points.

7. The design method of the U-shaped shell reinforced shield tunnel structure according to claim 6, characterized in that: The standard solid logic specifically includes: Set the fixed border based on the anchor border, and set the anchor points at the corners of the fixed border. The expression of the fixed border is: in, , is the area of ​​the solid frame, is the area of ​​the anchor border.

8. A U-shaped shell reinforced shield tunnel structure, applied to the design method of a U-shaped shell reinforced shield tunnel structure according to any one of claims 1 to 7, characterized in that: The invention comprises a tunnel segment (101) fixed to the inner wall of a shield tunnel, the outer wall of the tunnel segment (101) being provided with a fixing groove (102) and the inner wall of the fixing groove (102) being screwed with a socket (103), the outer wall of the tunnel segment (101) being screwed with a fixing head (104), the inner wall of the tunnel segment (101) being provided with a hand hole (105) and the inner wall of the tunnel segment (101) being screwed with a chemical anchor bolt (106).

9. The U-shaped shell reinforced shield tunnel structure according to claim 8, characterized in that: The inner wall of the tunnel segment (101) is provided with a U-shaped shell (201), the end of the U-shaped shell (201) is provided with a variable cross-section (202), the end of the U-shaped shell (201) is also provided with a placement groove (203), the outside of the placement groove (203) is provided with a reinforcement plate (204), the inner wall of the tunnel segment (101) is also provided with a ballast (301), and the outer wall of the ballast (301) is provided with a bracket (302).

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