A method for determining the overburden pressure of a shield tunneling tunnel

Abstract

The present invention provides a method for determining the overburden pressure of a shield tunneling tunnel, which relates to the technical field of overburden pressure determination. The method includes: obtaining a calculation theoretical model corresponding to the overburden of the shield tunneling tunnel; determining the dilatancy mobilization coefficient at different stress levels according to the calculation theoretical model; determining the included angle between the tunnel excavation shear zone and the horizontal direction corresponding to the dilatancy angle at different stress levels according to; determining the calculation formula of the overburden pressure of the tunnel with respect to the soil arch height and the calculation formula of the soil arch height with respect to the ground loss rate according to; according to the calculation formula of the overburden pressure of the tunnel with respect to the soil arch height and the calculation formula of the soil arch height with respect to the ground loss rate, determining the calculation formula of the overburden pressure of the tunnel with respect to the ground loss rate, and further determining the overburden pressure of the shield tunneling tunnel. The method in the present invention comprehensively considers various factors and can accurately determine the overburden pressure of the shield tunneling tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of overburden pressure determination, and particularly to a method for determining the overburden pressure of a shield tunneling tunnel. Background Art

[0002] With the accelerating urbanization process, the development of underground space has become an important means to increase the available urban space and relieve traffic pressure. As a method for underground space construction, the shield method has been widely applied in fields such as transportation, electricity, and water conservancy. Shield tunneling will cause an arching effect in the internal strata, resulting in obvious changes in the overburden pressure of the tunnel; therefore, reasonably evaluating the evolution process of the arching effect during shield tunneling and proposing an arching effect theory based on this is a prerequisite for accurately predicting the overburden pressure during tunnel excavation; currently, although a large number of tunnel excavation arching effect theories have been proposed in the prior art based on model test and numerical simulation results, combined with the limit equilibrium analysis of soil masses, there are still many limitations in the relevant theories, and the determination of the overburden pressure of a shield tunneling tunnel is still not accurate enough, resulting in inaccurate setting of relevant parameters during shield tunneling. Therefore, how to accurately determine the overburden pressure of a shield tunneling tunnel has become an urgent technical problem to be solved. Summary of the Invention

[0003] For the above technical problems, the technical solution adopted by the present invention is as follows:

[0004] According to the first aspect of the present application, a method for determining the overburden pressure of a shield tunneling tunnel is provided, and the method includes the following steps:

[0005] S100, obtaining a calculation theoretical model corresponding to the overburden of a shield tunneling tunnel;

[0006] S200, determining the dilation coefficient at different stress levels according to the calculation theoretical model ;

[0007] S300, according to , determining the included angle between the tunnel excavation shear zone and the horizontal direction corresponding to the dilation angle at different stress levels ;

[0008] S400, according to , determining the calculation formula of the overburden pressure of the tunnel with respect to the arch height and the calculation formula of the arch height with respect to the ground loss rate;

[0009] S500, according to the calculation formula of the overburden pressure of the tunnel with respect to the arch height and the calculation formula of the arch height with respect to the ground loss rate, determining the calculation formula of the overburden pressure of the tunnel with respect to the ground loss rate, and further determining the overburden pressure of the shield tunneling tunnel.

[0010] According to another aspect of the present application, there is also provided a non-transitory computer-readable storage medium storing at least one instruction or at least one program segment, and the at least one instruction or at least one program segment is loaded and executed by a processor to implement the above method for determining the overburden pressure of a shield tunneling tunnel.

[0011] According to another aspect of the present application, there is also provided an electronic device including a processor and the above non-transitory computer-readable storage medium.

[0012] The present invention has at least the following beneficial effects:

[0013] The method for determining the overburden pressure of a shield tunneling tunnel according to the present invention obtains a calculation theoretical model corresponding to the overburden of the shield tunneling tunnel; according to the calculation theoretical model, the dilatancy coefficient at different stress levels is determined f y ; according to f y , the included angle between the tunnel excavation shear zone and the horizontal direction corresponding to the dilatancy angle at different stress levels is determined a s ; according to a s , the calculation formula of the overburden pressure of the tunnel with respect to the soil arch height and the calculation formula of the soil arch height with respect to the ground loss rate are determined; according to the calculation formula of the overburden pressure of the tunnel with respect to the soil arch height and the calculation formula of the soil arch height with respect to the ground loss rate, the calculation formula of the overburden pressure of the tunnel with respect to the ground loss rate is determined, and then the overburden pressure of the shield tunneling tunnel is determined. The method in the present invention comprehensively considers various factors and can accurately determine the overburden pressure of the shield tunneling tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings without creative efforts based on these drawings.

[0015] Figure 1 is a flowchart of the method for determining the overburden pressure of a shield tunneling tunnel provided by an embodiment of the present invention;

[0016] Figure 2 is a schematic diagram of specific implementation steps provided by an embodiment of the present invention;

[0017] Figure 3 is a schematic diagram of the calculation theoretical model provided by an embodiment of the present invention;

[0018] Figure 4 is a schematic diagram of stress analysis provided by an embodiment of the present invention;

[0019] Figure 5 Schematic diagram of the Mohr circle of the soil mass inside the shear plane provided by the embodiment of the present invention;

[0020] Figure 6 Schematic diagram of the Mohr circle of the soil mass at the shear plane provided by the embodiment of the present invention;

[0021] Figure 7 Schematic diagram of the force analysis of the unit body provided by the embodiment of the present invention;

[0022] Figure 8 Schematic diagram of the shear band provided by the embodiment of the present invention;

[0023] Figure 9 Schematic diagram of the comparison between the theoretical results and the test results provided by the embodiment of the present invention. Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0025] It should be noted that based on this disclosure, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, this device and / or this method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0026] Next, reference will be made to Figure 1 the flowchart of the method for determining the overburden pressure of a shield tunneling tunnel shown, and a method for determining the overburden pressure of a shield tunneling tunnel will be introduced.

[0027] Refer to Figure 2 , when the method for determining the overburden pressure of a shield tunneling tunnel is specifically implemented, it may include the following steps:

[0028] S100, obtain the calculation theoretical model corresponding to the overburden of the shield tunneling tunnel.

[0029] Refer to Figure 3 , which is the calculation theoretical model of the overburden pressure of the tunnel. The model is mainly composed of an upper inverted trapezoid (or rectangle) and a lower classified triangle. The starting positions of the shear planes on both sides of the calculated width of the soil arch are at the intersections of the ±45° radius centered on the tunnel center line and the circumference.

[0030] When the stress level is small, the shear plane develops vertically upward; when the stress level is large and the soil dilatancy is weak, the shear plane develops obliquely to both sides; the calculated height of the soil arch is h sa , when the buried depth C is greater than the calculated height of the soil arch h sa , the strata above the calculated height of the soil arch are considered not to be affected by the tunnel excavation.

[0031] The calculated height of the soil arch increases with the increase of the ground loss rate. When the tunnel buried depth is shallow, the soil arch may develop rapidly to the ground surface with the increase of the ground loss rate; while when the tunnel buried depth is large, the height of the soil arch may not reach the ground surface. The calculated width of the soil arch at the top of the tunnel is 2 B , and the calculated width of the soil arch at each upper position is .

[0032] The model assumptions are as follows:

[0033] (1) The type of soil arch above the tunnel excavation is a circular arc major principal stress arch;

[0034] (2) The soil inside the soil arch area is in the limit state and conforms to the Mohr-Coulomb failure criterion;

[0035] (3) The ground loss during shield tunneling is filled by the volume change generated by the soil dilatancy in the upper shear zone.

[0036] S200. According to the calculation theory model, determine the dilatancy coefficient under different stress levels.

[0037] The dilatancy coefficient under different stress levels is determined according to the following formula:

[0038] ;

[0039] In the formula, is the mean effective stress p ' is the peak soil dilatancy angle at 150 kPa; is the mean effective stress p ' is the maximum soil dilatancy angle when the mean effective stress

[0040] S300. According to , determine the angle between the tunnel excavation shear zone and the horizontal direction corresponding to the dilatancy angle under different stress levels; it can be determined by linear interpolation with the following formula:

[0041] ;

[0042] where, is the internal friction angle of the soil mass.

[0043] In the third step, determine the calculation formula of the overburden pressure of the tunnel with respect to the height of the soil arch.

[0044] Refer to Figure 3 , which is the angle between the direction of the major principal stress of the soil mass at the shear plane and the vertical direction, , and is the angle between the direction of the major principal stress of the soil mass at the shear plane and the shear plane; is the angle between the direction of the major principal stress at a certain point on the major principal stress trace line and the vertical direction, . is the normal stress perpendicular to the shear plane, is the shear stress parallel to the shear plane, is the radius of the major principal stress trace line of the circular arc soil arch.

[0045] The calculation of relevant parameters is as follows:

[0046] ;

[0047] ;

[0048] ;

[0049] ;

[0050] Among them, D is the tunnel diameter, C is the tunnel burial depth, and z is the vertical coordinate.

[0051] Refer to Figure 4 and Figure 5 , and the relationship between the major and minor principal stresses of the soil mass at any position in the shear plane and the vertical and horizontal principal stresses during the shield tunneling process can be obtained:

[0052] ;

[0053] ;

[0054] By combining the above two equations, the lateral earth pressure coefficient can be obtained as:

[0055] ;

[0056] In the formula, , is the passive earth pressure coefficient; σ 1 is the major principal stress, σ 3 is the minor principal stress, σ v is the vertical earth pressure, σ h is the horizontal earth pressure.

[0057] On the tunnel center line , the lateral earth pressure coefficient K o = K p ; On the shear plane , the lateral earth pressure coefficient K s The calculation formula is as follows:

[0058] ;

[0059] Referring to Figure 6 , the normal stress , shear stress at the shear plane and the relationship with the major and minor principal stresses can be obtained:

[0060] ;

[0061] ;

[0062] ;

[0063] is the angle between the direction of the major principal stress of the soil mass at the shear plane and the shear plane.

[0064] Referring to Figure 7 , performing a force analysis on the unit body, we can obtain:

[0065] ;

[0066] ;

[0067] Determine the lateral earth pressure coefficient K av :

[0068] ;

[0069] Determine the normal stress at the shear plane:

[0070] ;

[0071] ;

[0072] Determine the shear stress at the shear plane:

[0073] ;

[0074] is the shear stress parallel to the shear plane, is the average vertical earth pressure.

[0075] Determine the differential equation:

[0076] ;

[0077] where, is the unit weight of soil.

[0078] Solving the above equation, let , and write it in the form of a first-order non-homogeneous linear differential equation as :

[0079] ;

[0080] Solving the above equation, we get:

[0081] ;

[0082] In the formula, C 1 is a constant to be determined.

[0083] Substitute the boundary condition: when z = C - h sa , .

[0084] We get:

[0085] ;

[0086] The calculation condition of the above formula needs to satisfy C - h sa ≤ z ≤ C .

[0087] The overburden pressure of the tunnel The calculation formula is:

[0088] ;

[0089] When the average effective stress p '< 150 kPa, the stress level has little effect on the dilatancy of the soil. At this time , the above formula cannot be directly solved, and it can be approximated by taking the limit.

[0090] By solving, the overburden pressure of the tunnel s av2 The calculation formula is:

[0091] ;

[0092] S400, according to , the calculation formulas for the overburden pressure of the tunnel with respect to the height of the soil arch and the height of the soil arch with respect to the ground loss rate are determined.

[0093] Refer to Figure 8 , simplify the volume of the shear zone to ( V 1 + V 2):

[0094] ;

[0095] ;

[0096] Among them, V 1 is the volume of the shear zone above the plane at the top of the tunnel, V 2 is the volume of the shear zone below the plane at the top of the tunnel.

[0097] In this embodiment, the critical void ratio is used to calculate the volume change of the shear zone, and the change in void ratio is , among which, e 0 is the initial void ratio. The volume change caused by the dilation of the soil mass inside the shear zone is . According to the above assumption 3, it can be known that it is equal to the volume of the excavated ground loss, and the following formula can be obtained:

[0098] ;

[0099] Calculating the above formula gives the calculation formulas for the height of the soil arch and the ground loss rate:

[0100] ;

[0101] In the formula,

[0102] ;

[0103] S500, according to the calculation formula for the overburden pressure of the tunnel with respect to the height of the soil arch and the calculation formula for the height of the soil arch with respect to the ground loss rate, determine the calculation formula for the overburden pressure of the tunnel with respect to the ground loss rate, and then determine the overburden pressure of the shield tunneling tunnel.

[0104] Substitute the above two formulas into the calculation formulas of the aforementioned overburden pressure of the tunnel and , and the magnitude of the overburden pressure during the excavation of the deep / shallow buried shield tunnel can be obtained.

[0105] In the above two equations, for the displacement mode in which the model tunnel in the model test uniformly contracts towards the tunnel center, it will cause a large amount of rebound deformation in the stratum at the bottom of the tunnel. It can be considered that half of the stratum loss caused by tunnel excavation is filled by the dilation of the upper shear zone. That is, a coefficient of 0.5 needs to be multiplied on the left side of the formula. For actual engineering, the above formula can be directly used for calculation.

[0106] In the prior art, through the tunnel excavation centrifugal model test, the variation law of the overburden pressure of the tunnel with the increase of the stratum loss rate was obtained. The prototype tunnel diameter is 3.2m, the unit weight of the soil is 14.61kN / m 3 , the internal friction angle of the soil is 32°, the initial void ratio is 0.814, and the buried depth ratio is 6.3. To verify the accuracy of the above theoretical calculation method, the above theory was used to calculate the test conditions in the prior art.

[0107] Refer to Figure 9 , which is the comparison chart of the theoretical calculation results of this theory with the test results and the theory in the prior art. From Figure 9 it can be seen that the theoretical calculation results of this theory are in good agreement with the measured results, indicating that this theoretical model can accurately predict the overburden pressure of the tunnel under different stratum losses.

[0108] The method for determining the overburden pressure of the shield tunneling tunnel in this embodiment obtains the calculation theoretical model corresponding to the overburden of the shield tunneling tunnel; according to the calculation theoretical model, determine the dilation coefficient at different stress levels f y ; according to f y , determine the included angle between the tunnel excavation shear zone and the horizontal direction corresponding to the dilation angle at different stress levels a s ; according to a s , determine the calculation formula of the overburden pressure of the tunnel with respect to the soil arch height and the calculation formula of the soil arch height with respect to the stratum loss rate; according to the calculation formula of the overburden pressure of the tunnel with respect to the soil arch height and the calculation formula of the soil arch height with respect to the stratum loss rate, determine the calculation formula of the overburden pressure of the tunnel with respect to the stratum loss rate, and then determine the overburden pressure of the shield tunneling tunnel. The method in the present invention comprehensively considers various factors and can accurately determine the overburden pressure of the shield tunneling tunnel.

[0109] In addition, although the steps of the method in the present disclosure are described in a specific order in the drawings, this does not require or imply that these steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step for execution, and / or one step may be decomposed into multiple steps for execution, etc.

[0110] Embodiments of the present invention also provide a non-transitory computer-readable storage medium, which can be disposed in an electronic device to store at least one instruction or at least one segment of program related to a method in method embodiments. The at least one instruction or the at least one segment of program is loaded and executed by the processor to implement the method provided in the above embodiments.

[0111] The program product can adopt any combination of one or more readable media. The readable media can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0112] The computer-readable signal medium can include a data signal propagated in a baseband or as part of a carrier wave, which carries the readable program code. Such a propagated data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable signal medium can also be any readable medium other than the readable storage medium, which can send, propagate, or transmit a program used by or in conjunction with an instruction execution system, apparatus, or device.

[0113] The program code contained on the readable medium can be transmitted by any appropriate medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination of the above.

[0114] The program code for performing the operations of the present application can be written in any combination of one or more programming languages. The programming languages include object-oriented programming languages - such as Java, C++, etc., and also include conventional procedural programming languages - such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computing device, partially on the user's device, executed as an independent software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user's computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, by using an Internet service provider to connect through the Internet).

[0115] An embodiment of the present invention also provides an electronic device, including a processor and the aforementioned non-transitory computer-readable storage medium.

[0116] The electronic device is merely an example and should not impose any limitation on the functions and usage scope of the embodiments of the present application.

[0117] The electronic device is presented in the form of a general-purpose computing device. The components of the electronic device may include, but are not limited to: at least one of the aforementioned processors, at least one of the aforementioned memories, and a bus connecting different system components (including the memory and the processor).

[0118] Wherein, the memory stores program codes, and the program codes can be executed by the processor, so that the processor executes the steps in various embodiments described in this specification.

[0119] The memory may include a readable medium in the form of a volatile memory, such as a random access memory (RAM) and / or a cache memory, and may further include a read-only memory (ROM).

[0120] The memory may further include a program / utilities having a set (at least one) of program modules. Such program modules include, but are not limited to: an operating system, one or more application programs, other program modules, and program data. The implementation of a network environment may be included in each or some combination of these examples.

[0121] The bus may represent one or more of several types of bus structures, including a memory bus or a memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any bus structure in a variety of bus structures.

[0122] The electronic device may also communicate with one or more external devices (such as a keyboard, a pointing device, a Bluetooth device, etc.), may also communicate with one or more devices that enable a user to interact with the electronic device, and / or communicate with any device that enables the electronic device to communicate with one or more other computing devices (such as a router, a modem, etc.). Such communication may be carried out through an input / output (I / O) interface. Moreover, the electronic device may also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through a network adapter. The network adapter communicates with other modules of the electronic device through the bus. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in combination with the electronic device, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, etc.

[0123] From the description of the above embodiments, those skilled in the art can easily understand that the exemplary embodiments described herein can be implemented by software or by a combination of software and necessary hardware. Therefore, the technical solutions according to the embodiments of the present disclosure can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, and includes several instructions to enable a computing device (such as a personal computer, a server, a terminal device, or a network device, etc.) to execute the method according to the embodiments of the present disclosure.

[0124] An embodiment of the present invention also provides a computer program product, which includes program code. When the program product runs on an electronic device, the program code is used to cause the electronic device to execute the steps in the methods according to various exemplary embodiments of the present invention described above in this specification.

[0125] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should also understand that various modifications can be made to the embodiments without departing from the scope and spirit of the present invention.

Claims

1. A method for determining the overburden pressure of a shield tunnel, characterized in that: The method comprises the following steps: S100, obtaining a calculation theoretical model corresponding to the overburden on the shield tunnel; S200, determining the shear expansion coefficient under different stress levels according to the calculation theoretical model ; S300, according to , determine the angle between the tunnel excavation shear zone and the horizontal direction corresponding to the shear dilation angle under different stress levels ; S400, according to , determine the calculation formula of the overburden pressure on the tunnel in relation to the soil arch height and the calculation formula of the soil arch height in relation to the stratum loss rate; S500, determining a calculation formula for the overburden pressure on the tunnel with respect to the stratum loss rate according to a calculation formula for the overburden pressure on the tunnel with respect to the soil arch height and a calculation formula for the soil arch height with respect to the stratum loss rate, and further determining the overburden pressure on the shield tunnel; The calculation theoretical model includes: an inverted trapezoid or rectangle on the upper part and a classified triangle on the lower part; the starting position of the shear surface on both sides of the soil arch calculation width is located at the intersection of the ±45° radius and the circumference based on the tunnel centerline; the soil arch calculation height is , when the burial depth C is greater than the calculated height of the soil arch When the soil arch is calculated, the strata above the soil arch calculation height are not affected by tunnel excavation; the soil arch calculation width at the tunnel top is 2 B , the calculated width of the soil arch at each position in the upper part is 2 B z ; ; It complies with the following formula: ； in, is the mean effective stress; p ' is the peak dilatancy angle of soil at 150 kPa; is the mean effective stress p 'The maximum dilatancy angle of soil when it is greater than 150kPa; It complies with the following formula: ； in, is the friction angle within the soil; B and B z It complies with the following formula: ； ； Where D is the tunnel diameter, C is the tunnel depth, and z is the vertical coordinate; The relationship between the major and minor principal stresses and the vertical and horizontal principal stresses of the soil at any position in the shear plane during shield tunneling: ； ； in, is the angle between the direction of the major principal stress at a point on the major principal stress trace and the vertical direction; , is the major principal stress, is the minor principal stress, is the vertical earth pressure, is the horizontal earth pressure; according to and , determine the lateral earth pressure coefficient K, where K conforms to the following formula: ； In the formula, K p is the passive earth pressure coefficient, ; On the tunnel centerline, , lateral earth pressure coefficient K o = K p On the shear plane, , is the angle between the major principal stress direction of the soil at the shear plane and the vertical direction, ; Lateral earth pressure coefficient K s The calculation formula is as follows: ； Get the normal stress at the shear surface , shear stress Relationship with major and minor principal stresses: ； ； ； in, is the angle between the direction of the major principal stress of the soil at the shear plane and the shear plane; and then we get: ； ； in, is the shear stress parallel to the shear plane, is the average vertical earth pressure; Determine the lateral earth pressure coefficient : ； Determine the normal stress at the shear plane: ； in is the ratio of the normal stress at the shear surface to the average vertical earth pressure; ； Determine the shear stress at the shear plane: ； Determine the differential equation: ； in, It is the weight of soil; Solve the above formula and set the default assignment parameter , will be written as The first-order nonhomogeneous linear differential equation form of is: ； Solving the above formula, we can get: ； In the formula, is a constant to be determined; Substitute the boundary conditions: when hour, ; We can get: ； The above calculation conditions must be met ; Overburden pressure on tunnel The calculation formula is: ； The overburden pressure on the tunnel can be obtained by solving The calculation formula is: ； Step S500 includes: The simplified shear band volume is V 1+ V 2, among which, V 1 is the volume of the shear zone above the tunnel top plane, V 2 is the volume of the shear zone below the tunnel top plane; where, ； ； Critical void ratio To calculate the volume change of the shear band, the change in porosity is ,in, is the initial porosity ratio; the volume change caused by the shear expansion of the soil in the shear zone is ;get: ； in, is the stratum loss rate, and the calculation formula of soil arch height and stratum loss rate is further obtained: ； in, ; Combination and The calculation formula is used to obtain the overburden pressure on the tunnel excavation.

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