Tunnel peripheral stratum characterization method rich in spatial physical information

Abstract

The invention discloses a tunnel surrounding stratum characterization method rich in space physical information, and belongs to the technical field of shield tunnel engineering. The characterization method comprises the following steps: calculating a rebound modulus of each stratum in a section where a tunnel corresponding ring is located; calculating the corrected rebound modulus E'ur of the stratum above the tunnel and the corrected Poisson's ratio mu 'of the stratum above the tunnel of the section, and representing the comprehensive properties of the stratum above the tunnel by using the two parameters; and calculating the weighted resilience modulus FEur of the tunnel face stratum, the difference degree FD of the tunnel face stratum, the composite ratio FC of the tunnel face stratum and the number FN of the tunnel face stratum, and representing the comprehensive properties of the stratum at the position of the cutterhead tunnel face during tunneling of the shield tunneling machine by using the four parameters. The method has the beneficial effects that the influence degree of the shield tunneling machine on the distribution condition of the stratum where the shield tunneling machine is located when the shield tunneling machine is excavated at each position is accurately and quantitatively reflected through the numerical values of the six indexes.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnel engineering, and in particular to a method for characterizing tunnel peripheral strata rich in spatial physical information. Background Art

[0002] During the construction of shield tunnels, the physical and mechanical properties of the strata that the shield machine passes through and the strata above the shield tunnel are important factors affecting the shield machine's excavation efficiency, tunnel construction safety, and disturbance range. When the shield machine passes through a stratum with good properties, the number of shutdowns during the advancement process is usually small, the working time required for each ring is short, and the range and intensity of the stratum disturbance caused by the shield machine excavation are relatively low. When the shield machine passes through a stratum with poor self-stabilization properties or a composite stratum with soft upper and hard lower layers and a broken zone, the construction risk is significantly increased, the construction efficiency is significantly reduced, and the scope and intensity of the impact of the shield construction on the strata around the tunnel are significantly increased. The properties of the strata above the tunnel will affect the deformation conduction mode of the strata, such as the degree of impact on the underground structures around the tunnel, the size and distribution of the surface settlement. Therefore, in related studies involving the calculation of the impact of shield machine excavation on the surrounding environment, it is crucial to fully consider and accurately characterize the physical and mechanical properties of the strata that the shield machine passes through and the strata above the shield tunnel.

[0003] However, in the current research on the construction impact caused by shield machine excavation and the response of the shield machine itself using machine learning methods, most of the research deals with the problem of how to select appropriate parameters to more accurately characterize the strata. For example, in previous studies, the strata where the shield tunnel vault is located are usually directly divided into several categories such as soft soil, hard soil, and rock, and then the strata types traversed by the shield machine are represented by specific numbers. Some studies represent the stratum conditions by selecting the physical and mechanical indicators of the strata traversed by the shield machine (such as cohesion, friction angle, and elastic modulus). Some studies also select the arithmetic average of the physical and mechanical indicators of all strata above the tunnel or the face to represent the comprehensive conditions of the strata where the shield tunnel is located. Although these processing methods can simply distinguish various stratum conditions, they usually ignore the distribution mode and depth thickness information between the strata, and the physical and mechanical indicators selected are usually not applicable to the stress deformation of the strata around the tunnel caused by the unloading and reloading of the strata around the tunnel during the construction of the shield machine. Therefore, it is necessary to innovate in the characterization of the strata around the tunnel. Summary of the invention

[0004] The purpose of the present invention is to provide a method for characterizing the strata around a tunnel that is rich in spatial physical information. The method calculates the rebound modulus of each ring of strata based on the small strain hardening constitutive model of soil, and then obtains the corrected rebound modulus of the strata above the tunnel and the corrected Poisson's ratio of the strata above the tunnel by using a normalized stratum depth and thickness correction method. At the same time, a method for calculating the weighted rebound modulus of the strata at the face, the strata difference at the face, and the composite ratio of the strata at the face is proposed. Combined with the number of strata at the face, the methods are used to characterize the strata properties at the tunnel face. Finally, the above six parameters are used to realize the comprehensive characterization of the physical and mechanical strength information and spatial information of the strata around the tunnel, thereby solving at least one technical problem involved in the background technology.

[0005] In order to solve the above-mentioned technical problems, the present invention is achieved as follows:

[0006] The present invention provides a method for characterizing the strata surrounding a tunnel that is rich in spatial physical information, characterized in that it comprises the following steps:

[0007] Step S1, calculating the modulus of resilience of each layer in the section where the corresponding ring of the tunnel is located;

[0008] Step S2, using the normalized stratum depth and thickness correction method to calculate the corrected elastic modulus E' of the stratum above the tunnel in the cross section ur and the modified Poisson's ratio μ′ of the stratum above the tunnel, and the modified rebound modulus E′ of the stratum above the tunnel ur The two parameters of modified Poisson's ratio μ′ of the stratum above the tunnel characterize the comprehensive properties of the stratum above the tunnel;

[0009] Step S3: Calculate the weighted elastic modulus FE of the stratum at the tunnel face ur , the difference degree of the strata at the face FD, the composite ratio of the strata at the face FC and the number of strata at the face FN, and the weighted elastic modulus FE of the strata at the face ur The four parameters of face stratum difference FD, face stratum composite ratio FC and face stratum number FN characterize the comprehensive properties of the stratum at the cutterhead face during shield machine excavation.

[0010] Optionally, in step S1, the modulus of resilience E of each layer in the section where the tunnel corresponding ring is located ur Calculated by the following formula:

[0011]

[0012] In the formula, is the unloading and reloading modulus under reference confining pressure measured in triaxial consolidation drainage loading and unloading test; c, are the effective cohesion and effective internal friction angle measured under triaxial consolidation drained or undrained test respectively; p refis the reference confining pressure; σ3′ is the minimum principal stress. When the upper load and soil arching effect are not considered, the static horizontal earth pressure σ0 can be taken; m is the power exponent related to the stiffness stress level measured by the triaxial consolidation drainage test or the standard consolidation test.

[0013] Optionally, for slightly weathered rocks, the elastic modulus can be directly taken as the rebound modulus E ur ; For other types of strata, c, The average value of triaxial test or direct shear test can be taken; for soft soil, fully weathered rock layer, and fully filled cave, when the compression modulus E s1-2 <3 o'clock, Take 7.5 times E s1-2 , m is 0.8; when 6 <E s1-2 <8 o'clock, Take 5 times E s1-2 , m is 0.75; when E s1-2 >18:00, Take 3 times E s1-2 , m is 0.6; when E s1-2 When it is in the middle value, linear interpolation is performed; for dense sand, gravel, pebbles, and strongly weathered rocks, the formula Calculate the compression modulus E s , Take 2.5 times E s , m is taken as 0.5, where ξ is the lateral pressure coefficient of the soil.

[0014] Optionally, in step S2, the modified elastic modulus E of the stratum above the tunnel is u ' r Calculated by the following formula:

[0015]

[0016] In the formula, E ur,i is the elastic modulus of the ith stratum; β i is the normalized depth thickness correction factor and is calculated by the following formula:

[0017]

[0018] In the formula, t i is the thickness of the ith stratum; h i is the burial depth of the i-th stratum; h is the burial depth of the tunnel; is the thickness correction factor; is the depth correction factor.

[0019] Optionally, the modified Poisson's ratio μ′ of the stratum above the tunnel is calculated by the following formula:

[0020]

[0021] Where μ is the Poisson's ratio of the stratum above the tunnel.

[0022] Optional, weighted resilience modulus FE of the tunnel face formation ur Calculated by the following formula:

[0023]

[0024] Where FE ur,i is the resilience modulus of the ith stratum at the tunnel face; Fh n is the total thickness of the strata, and n represents the number of strata contained in the entire tunnel face.

[0025] Optionally, when the tunnel face of a ring contains only soft soil and hard soil, FE ur,Ⅲ , FE ur,Ⅳ Set to 0; include FE ur,Ⅲ , FE ur,Ⅳ The absolute value sub-term of |FE ur,Ⅰ -FE ur,Ⅲ |、|FE ur,Ⅰ -FE ur,Ⅳ |、|FE ur,Ⅱ -FE ur,Ⅲ |、|FE ur,Ⅱ -FE ur,Ⅳ |、|FE ur,Ⅲ -FE ur,Ⅳ | are all set to 0, so the calculation formula for the formation difference FD around the tunnel face is:

[0026]

[0027] Optionally, the face formation composite ratio FC is calculated by the following formula:

[0028]

[0029] In the formula, Fh Ⅰ is the total thickness of Class I strata, which include all clay, sand, plain fill, fully filled caves, and fully weathered rock strata with lateral pressure coefficient ξ>0.43 or Poisson's ratio μ>0.3 in the tunnel face; Fh Ⅱ is the total thickness of Class II formations, which include all clay, sand, plain fill, fully filled caves, fully weathered rock layers, gravel and pebbles with lateral pressure coefficient ξ<0.43 and Poisson's ratio μ<0.3 in the face; Fh Ⅲ is the total thickness of Class III formations, which include all types of strongly weathered rock formations in the tunnel face; Fh Ⅳ is the total thickness of Class IV strata, which include all types of moderately to slightly weathered rock strata in the face.

[0030] Optionally, the number of layers FN at the tunnel face is FhⅠ , Fh Ⅱ , Fh Ⅲ , Fh Ⅳ The number of variables that are not zero in .

[0031] Optionally, the face stratum difference FD is calculated by the following formula:

[0032]

[0033] Where FE ur,Ⅰ is the comprehensive elastic modulus of Class I strata obtained by weighting the elastic modulus of each Class I stratum by thickness; FE ur,Ⅱ is the comprehensive elastic modulus of Class II strata obtained by weighting the elastic modulus of each Class II strata by thickness; FE ur,Ⅲ is the comprehensive elastic modulus of Class III strata obtained by weighting the elastic modulus of each Class III strata by thickness; FE ur,Ⅳ The comprehensive resilience modulus of Class IV strata is obtained by weighting the resilience modulus of each Class IV strata by thickness.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention proposes six indicators to characterize the strata around the tunnel in combination with the spatial distribution of the strata, among which: the modified elastic modulus E′ of the stratum above the tunnel ur The two parameters of modified Poisson's ratio μ′ of the stratum above the tunnel are used to characterize the comprehensive properties of the stratum above the tunnel; the weighted elastic modulus FE of the stratum at the tunnel face ur The four parameters of face stratum difference FD, face stratum composite ratio FC and face stratum number FN are used to characterize the location of the tunnel, that is, the comprehensive properties of the stratum where the cutterhead face is located when the shield machine is excavating. The values ​​of the six indicators can be used to accurately and quantitatively reflect the degree to which the shield machine is affected by the distribution of the strata when excavating at various positions.

[0036] 2. The present invention innovatively uses the modulus of resilience combined with a correction method specially designed for different stratum types to unify the evaluation indicators of the properties of various types of strata, from soft soil to hard soil to rock, in tunnel construction.

[0037] 3. In addition to using the rebound modulus, the present invention also introduces Poisson's ratio as a supplement to the deformation properties of the formation, and innovatively characterizes various aspects of the formation properties from multiple dimensions in a complementary manner.

[0038] 4. In addition to weighted correction based on thickness and depth, the correction method for the stratum above the tunnel of the present invention also introduces a normalized correction factor indicator to eliminate the calculation error introduced in the mathematical operation process, which has a clear spatial physical information meaning.

[0039] 5. In addition to characterizing the strata above the tunnel, the present invention also carries out a refined characterization of the strata at the tunnel face. In addition to paying attention to the comprehensive rebound modulus of the strata at the tunnel face, it also pays attention to the difference of the strata at the face, which is used to evaluate and characterize the soft and hard composite strata with extremely high risk in the project. It finely represents the difference, degree of compositeness and number of strata types of each stratum at the face, and realizes the quantitative assessment of construction risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0041] Figure 1 It is a schematic diagram of the distribution of strata above the tunnel provided by the present invention;

[0042] Figure 2 It is a schematic diagram of the stratum distribution of the tunnel face provided by the present invention. DETAILED DESCRIPTION

[0043] The technical solutions in the present invention will be described clearly and completely below in combination with the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The present invention provides a method for characterizing the strata around a tunnel that is rich in spatial physical information, characterized in that it comprises the following steps:

[0045] Step S1, calculating the modulus of resilience of each layer in the section where the corresponding ring of the tunnel is located;

[0046] Step S2, using the normalized stratum depth and thickness correction method to calculate the corrected elastic modulus E' of the stratum above the tunnel in the cross section ur and the modified Poisson's ratio μ′ of the stratum above the tunnel, and the modified rebound modulus E′ of the stratum above the tunnel ur The two parameters of modified Poisson's ratio μ′ of the stratum above the tunnel characterize the comprehensive properties of the stratum above the tunnel;

[0047] Step S3: Calculate the weighted elastic modulus FE of the stratum at the tunnel face ur , the difference degree of the strata at the face FD, the composite ratio of the strata at the face FC and the number of strata at the face FN, and the weighted elastic modulus FE of the strata at the face urThe four parameters, namely, face stratum difference degree FD, face stratum composite ratio FC and face stratum number FN, characterize the comprehensive properties of the stratum at the cutterhead face (i.e., the tunnel location) during shield machine excavation.

[0048] In step S1, the modulus of resilience E of each layer in the section where the tunnel corresponding ring is located ur Calculated by the following formula:

[0049]

[0050] In the formula, is the unloading and reloading modulus under reference confining pressure measured in triaxial consolidation drainage loading and unloading test; c, are the effective cohesion and effective internal friction angle measured under triaxial consolidation drained or undrained test respectively; p ref is the reference confining pressure; σ′3 is the minimum principal stress. When the upper load and soil arching effect are not considered, the static horizontal earth pressure σ0 can be taken; m is the power exponent related to the stiffness stress level measured by the triaxial consolidation drainage test or the standard consolidation test.

[0051] It should be noted that because the stratum distribution above each ring of the tunnel is different, the stress state is also different. The static horizontal earth pressure σ0 needs to be calculated based on the actual stratum distribution of the corresponding cross section of the ring.

[0052] When only geological survey reports are available as a reference for the physical and mechanical properties of the formation, the modulus of resilience E ur The parameters in the calculation formula can be calculated according to the following principles: For slightly weathered rocks, the elastic modulus is directly taken as the rebound modulus E ur ; For other types of strata, c, The average value of triaxial test or direct shear test can be taken; for soft soil, fully weathered rock layer, and fully filled cave, usually only the compression modulus E corresponding to 100-200 kPa in the consolidation test is given. s1-2 The formation, when the compression modulus E s1-2 <3 o'clock, Take 7.5 times E s1-2 , m is 0.8; when 6 <E s1-2 <8 o'clock, Take 5 times E s1-2 , m is 0.75; when E s1-2 >18:00, Take 3 times E s1-2 , m is 0.6; when E s1-2 When it is in the middle value, linear interpolation is performed; for dense sand, gravel, pebbles, and strongly weathered rocks, the formula Calculate the compression modulus E s , Take 2.5 times Es , m is taken as 0.5, where ξ is the lateral pressure coefficient of the soil.

[0053] In step S2, combined Figure 1 As shown, the modified elastic modulus E of the stratum above the tunnel u ' r Calculated by the following formula:

[0054]

[0055] In the formula, E ur,i is the elastic modulus of the ith stratum; β i is the normalized depth thickness correction factor and is calculated by the following formula:

[0056]

[0057] In the formula, t i is the thickness of the ith stratum; h i is the burial depth of the i-th stratum; h is the burial depth of the tunnel; is the thickness correction factor; is the depth correction factor.

[0058] The modified Poisson's ratio μ′ of the stratum above the tunnel is calculated by the following formula:

[0059]

[0060] Where μ is the Poisson's ratio of the stratum above the tunnel.

[0061] In step S3, combined Figure 2 As shown in the figure, the weighted elastic modulus FE of the stratum at the tunnel face ur Calculated by the following formula:

[0062]

[0063] Where FE ur,i is the resilience modulus of the ith stratum at the tunnel face; Fh n is the total thickness of the strata, and n represents the number of strata contained in the entire tunnel face.

[0064] It should be noted that when calculating the stratum difference degree FD of a certain ring, only the stratum type existing in the tunnel face needs to be considered. When a certain type of stratum does not exist in the tunnel face, the weighted elastic modulus corresponding to the non-existent stratum in the denominator of the calculation formula of the stratum difference degree FD of the tunnel face is set to 0, and all the absolute value sub-items of the weighted elastic modulus of the non-existent stratum in the numerator are set to 0. For example, when the tunnel face of a certain ring contains only soft soil and hard soil, the FE in the denominator is ur,Ⅲ , FE ur,Ⅳ Set to 0; FE is included in the numerator ur,Ⅲ, FE ur,Ⅳ The absolute value sub-term of |FE ur,Ⅰ -FE ur,Ⅲ |、|FE ur,Ⅰ -FE ur,Ⅳ |、|FE ur,Ⅱ -FE ur,Ⅲ |、|FE ur,Ⅱ -FE ur,Ⅳ |、|FE ur,Ⅲ -FE ur,Ⅳ | are all set to 0, so the calculation formula for the formation difference FD around the tunnel face is:

[0065]

[0066] The composite ratio FC of the tunnel face is calculated by the following formula:

[0067]

[0068] In the formula, Fh Ⅰ is the total thickness of Class I strata, which include all clay, sand, plain fill, fully filled caves, and fully weathered rock strata with lateral pressure coefficient ξ>0.43 or Poisson's ratio μ>0.3 in the tunnel face; Fh Ⅱ is the total thickness of Class II formations, which include all clay, sand, plain fill, fully filled caves, fully weathered rock layers, gravel and pebbles with lateral pressure coefficient ξ<0.43 and Poisson's ratio μ<0.3 in the face; Fh Ⅲ is the total thickness of Class III formations, which include all types of strongly weathered rock formations in the tunnel face; Fh Ⅳ is the total thickness of Class IV strata, which include all types of moderately to slightly weathered rock strata in the face.

[0069] The number of strata at the tunnel face FN is Fh Ⅰ , Fh Ⅱ , Fh Ⅲ , Fh Ⅳ The number of variables that are not zero in .

[0070] The stratum difference degree FD of the tunnel face is calculated by the following formula:

[0071]

[0072] Where FE ur,Ⅰ is the comprehensive elastic modulus of Class I strata obtained by weighting the elastic modulus of each Class I stratum by thickness; FE ur,Ⅱ is the comprehensive elastic modulus of Class II strata obtained by weighting the elastic modulus of each Class II strata by thickness; FE ur,Ⅲ is the comprehensive elastic modulus of Class III strata obtained by weighting the elastic modulus of each Class III strata by thickness; FE ur,ⅣThe comprehensive resilience modulus of Class IV strata is obtained by weighting the resilience modulus of each Class IV strata by thickness.

[0073] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0074] In addition, it should be noted that the scope of the methods and characterization methods in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0075] The embodiments of the present invention are described above, but the present invention is not limited to the above-mentioned specific implementation modes. The above-mentioned specific implementation modes are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for characterizing the strata around a tunnel that is rich in spatial physical information, characterized in that: The steps include: Step S1, calculating the modulus of resilience of each layer in the section where the corresponding ring of the tunnel is located; Step S2, using the normalized stratum depth and thickness correction method to calculate the corrected elastic modulus E' of the stratum above the tunnel in the cross section ur and the modified Poisson's ratio μ′ of the stratum above the tunnel, and the modified rebound modulus E′ of the stratum above the tunnel ur The two parameters of modified Poisson's ratio μ′ of the stratum above the tunnel characterize the comprehensive properties of the stratum above the tunnel; Step S3: Calculate the weighted elastic modulus FE of the stratum at the tunnel face ur , the difference degree of the strata at the face FD, the composite ratio of the strata at the face FC and the number of strata at the face FN, and the weighted elastic modulus FE of the strata at the face ur The four parameters of face stratum difference FD, face stratum composite ratio FC and face stratum number FN characterize the comprehensive properties of the stratum at the cutterhead face during shield machine excavation.

2. The method according to claim 1, characterized in that In step S1, the modulus of resilience E of each layer in the section where the tunnel corresponding ring is located ur Calculated by the following formula: In the formula, is the unloading and reloading modulus under reference confining pressure measured in triaxial consolidation drainage loading and unloading test; c, are the effective cohesion and effective internal friction angle measured under triaxial consolidation drained or undrained test respectively; p ref is the reference confining pressure; σ′3 is the minimum principal stress, and the static horizontal earth pressure σ0 is taken without considering the upper load and soil arch effect; m is the power exponent related to the stiffness stress level measured by the triaxial consolidation drainage test or the standard consolidation test.

3. The method according to claim 2, characterized in that For slightly weathered rocks, the elastic modulus is directly taken as the rebound modulus E ur ; For other types of strata, c, Take the average value of triaxial test or direct shear test; for soft soil, fully weathered rock layer, and fully filled cave, when the compression modulus E s1-2 <3 o'clock, Take 7.5 times E s1-2 , m is 0.8; when 6 <E s1-2 <8 o'clock, Take 5 times E s1-2 , m is 0.75; when E s1-2 >18:00, Take 3 times E s1-2 , m is 0.6; when E s1-2 When it is in the middle value, linear interpolation is performed; for dense sand, gravel, pebbles, and strongly weathered rocks, the formula Calculate the compression modulus E s , Take 2.5 times E s , m is taken as 0.5, where ξ is the lateral pressure coefficient of the soil.

4. The method according to claim 1, characterized in that: In step S2, the modulus of resilience E′ of the stratum above the tunnel is corrected ur Calculated by the following formula: In the formula, E ur,i is the elastic modulus of the ith stratum; β i is the normalized depth thickness correction factor and is calculated by the following formula: Where, t i is the thickness of the ith stratum; h i is the burial depth of the i-th stratum; h is the burial depth of the tunnel; is the thickness correction factor; is the depth correction factor.

5. The method according to claim 4, characterized in that The modified Poisson's ratio μ′ of the stratum above the tunnel is calculated by the following formula: Where μ is the Poisson's ratio of the stratum above the tunnel.

6. The method according to claim 5, characterized in that Weighted elastic modulus FE of the tunnel face stratum ur Calculated by the following formula: Where, FE ur,i is the resilience modulus of the ith stratum at the tunnel face; Fh n is the total thickness of the strata, and n represents the number of strata contained in the entire tunnel face.

7. The method according to claim 6, characterized in that When the tunnel face of a ring contains only soft soil and hard soil, FE ur,Ⅲ , FE ur,Ⅳ Set to 0; include FE ur,Ⅲ , FE ur,Ⅳ The absolute value sub-term of |FE ur,Ⅰ -FE ur,Ⅲ |、|FE ur,Ⅰ -FE ur,Ⅳ |、|FE ur,Ⅱ -FE ur,Ⅲ |、|FE ur,Ⅱ -FE ur,Ⅳ |、|FE ur,Ⅲ -FE ur,Ⅳ | are all set to 0, so the calculation formula for the formation difference FD around the tunnel face is:

8. The method according to claim 7, characterized in that The composite ratio FC of the tunnel face is calculated by the following formula: In the formula, Fh Ⅰ is the total thickness of Class I strata, which include all clay, sand, plain fill, fully filled caves, and fully weathered rock strata with lateral pressure coefficient ξ>0.43 or Poisson's ratio μ>0.3 in the tunnel face; Fh Ⅱ is the total thickness of Class II formations, which include all clay, sand, plain fill, fully filled caves, fully weathered rock layers, gravel and pebbles with lateral pressure coefficient ξ<0.43 and Poisson's ratio μ<0.3 in the face; Fh Ⅲ is the total thickness of Class III formations, which include all types of strongly weathered rock formations in the tunnel face; Fh Ⅳ is the total thickness of Class IV strata, which include all types of moderately to slightly weathered rock strata in the face.

9. The method according to claim 8, characterized in that The number of strata at the tunnel face FN is Fh Ⅰ , Fh Ⅱ , Fh Ⅲ , Fh Ⅳ The number of variables that are not zero in .

10. The method according to claim 8, characterized in that The stratum difference degree FD of the tunnel face is calculated by the following formula: Where FE ur,Ⅰ is the comprehensive elastic modulus of Class I strata obtained by weighting the elastic modulus of each Class I stratum by thickness; FE ur,Ⅱ is the comprehensive elastic modulus of Class II strata obtained by weighting the elastic modulus of each Class II strata by thickness; FE ur,Ⅲ is the comprehensive elastic modulus of Class III strata obtained by weighting the elastic modulus of each Class III strata by thickness; FE ur,Ⅳ The comprehensive resilience modulus of Class IV strata is obtained by weighting the resilience modulus of each Class IV strata by thickness.

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