A method for characterizing the strata surrounding a tunnel rich in spatial physical information

Abstract

This invention discloses a method for characterizing the strata surrounding a tunnel, rich in spatial physical information, belonging to the field of shield tunnel engineering technology. The characterization method includes the following steps: calculating the resilient modulus of each stratum in the cross-section corresponding to the tunnel ring; calculating the corrected resilient modulus E′ of the strata above the tunnel in the cross-section. ur The corrected Poisson's ratio μ′ of the strata above the tunnel is calculated, and these two parameters are used to characterize the combined properties of the strata above the tunnel; the weighted resilient modulus FE of the strata at the tunnel face is calculated. ur The invention employs four parameters—face stratum difference degree (FD), face stratum composite ratio (FC), and face stratum number (FN)—to characterize the comprehensive properties of the strata at the cutterhead face location during tunnel boring machine (TBM) excavation. The beneficial effect of this invention is that it accurately and quantitatively reflects the degree to which the TBM is affected by the distribution of the surrounding strata at various excavation locations through the values ​​of these six indicators.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel engineering technology, and specifically to a method for characterizing the strata surrounding a tunnel that is rich in spatial physical information. Background Technology

[0002] In the construction of shield tunnels, the physical and mechanical properties of the strata traversed by the tunnel boring machine (TBM) and the strata above the tunnel are crucial factors affecting the TBM's excavation efficiency, tunnel construction safety, and the extent of disturbance. When the TBM traverses strata with favorable properties, the number of downtimes during advancement is typically lower, the working time per ring is shorter, and the range and intensity of ground disturbance caused by the TBM's excavation are relatively lower. However, when the TBM traverses strata with poor self-stability, or composite strata with a soft upper layer and a hard lower layer, or fractured zones, the construction risk increases significantly, the construction efficiency decreases significantly, and the range and intensity of the impact of the TBM construction on the surrounding strata increase significantly. The properties of the strata above the tunnel affect the deformation transmission mode of the strata, such as the degree of impact on underground structures around the tunnel, and the magnitude and distribution of surface settlement. Therefore, in studies involving the calculation of the impact of TBM excavation on the surrounding environment, it is essential to fully consider and accurately characterize the physical and mechanical properties of the strata traversed by the TBM and the strata above the tunnel.

[0003] However, in current research using machine learning methods to study the construction impacts and responses of tunnel boring machines (TBMs) during tunneling, most studies have adopted a rather simplistic approach to the question of how to select appropriate parameters for a more accurate characterization of the geological strata. For example, early studies typically categorized the strata surrounding the tunnel arch into soft soil, hard soil, and rock, and then used specific numerical values ​​to represent the type of strata traversed by the TBM. Some studies used physical and mechanical parameters (such as cohesion, friction angle, and elastic modulus) to represent the geological conditions. Others used an arithmetic average of the physical and mechanical parameters of all strata traversed above the tunnel or at the tunnel face to represent the overall geological conditions of the strata. While these approaches can provide a basic distinction between various geological conditions, they often neglect the distribution and depth information of the strata, and the selected physical and mechanical parameters are usually not applicable to the stress and deformation of the surrounding strata caused by unloading and reloading during TBM construction. Therefore, it is necessary to innovate the methods for characterizing the strata surrounding the tunnel. Summary of the Invention

[0004] The purpose of this invention is to provide a method for characterizing the strata surrounding a tunnel that is rich in spatial physical information. It calculates the resilient modulus of each ring of strata based on a small-strain hardening constitutive model of soil, and then obtains the corrected resilient modulus and corrected Poisson's ratio of the strata above the tunnel by using a normalized method for correcting strata depth and thickness. Simultaneously, it proposes a method for calculating the weighted resilient modulus, strata difference, and composite ratio of the strata at the tunnel face, combined with the number of strata at the tunnel face, to characterize the strata properties at the tunnel face. Finally, by using the above six parameters, a comprehensive characterization of the physical and mechanical strength information and spatial information of the strata surrounding the tunnel is achieved, thereby solving at least one of the technical problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0006] This invention provides a method for characterizing the strata surrounding a tunnel that is rich in spatial physical information, characterized by comprising the following steps:

[0007] Step S1: Calculate the resilient modulus of each stratum in the cross section where the tunnel ring is located;

[0008] Step S2: Calculate the corrected resilient modulus of the strata above the tunnel at the cross-section using the normalized stratum depth and thickness correction method. Corrected Poisson's ratio of the strata above the tunnel And the resilient modulus was corrected using the strata above the tunnel. Corrected Poisson's ratio with the strata above the tunnel Two parameters characterize the combined properties of the strata above the tunnel;

[0009] Step S3: Calculate the weighted resilient modulus of the formation at the tunnel face. FE ur Structural variation at the working face FD Formation composite ratio at the working face FC Number of layers at the working face FN and the weighted resilient modulus of the formation at the working face FE ur Structural variation at the working face FD Formation composite ratio at the working face FC Number of layers at the working face FN The four parameters characterize the comprehensive properties of the strata at the location of the cutterhead face during tunnel boring machine excavation.

[0010] Optionally, in step S1, the resilient modulus of each stratum in the cross section corresponding to the tunnel ring is... Calculated by the following formula:

[0011]

[0012] In the formula, The unloading and reloading modulus under the reference confining pressure was measured in a triaxial consolidated drained loading and unloading test. c、 φ The effective cohesion and effective internal friction angle were measured under triaxial consolidated drained or undrained tests, respectively. p ref For reference confining pressure; The minimum principal stress can be taken as the static horizontal earth pressure σ0 without considering the overhead load and soil arching effect; m is the stiffness stress level related power exponent measured by the triaxial consolidated drained test or standard consolidated test.

[0013] Optionally, for moderately weathered rocks, the elastic modulus can be directly taken as the resilient modulus. For other types of strata, c, φ The average value of triaxial or direct shear tests can be used; for soft soil, completely weathered rock layers, and fully filled karst caves, 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 taken as 0.75; when E s1-2 >18:00, Take 3 times E s1-2 m is 0.6; when E s1-2 When the value is in the middle, linear interpolation is performed; for dense sand, gravel, pebbles, and strongly weathered rock, the formula is used. Calculate the compressive 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 resilient modulus of the strata above the tunnel is corrected. Calculated by the following formula:

[0015]

[0016] In the formula, E ur,i Let i be the resilient modulus of the i-th stratum; This is the normalized depth-thickness correction factor, calculated by the following formula:

[0017]

[0018] In the formula, t i For the first i The thickness of each stratum; h i For the first i The burial depth of each stratum; h For tunnel burial depth; This is a thickness correction factor; This is a depth correction factor.

[0019] Optionally, the Poisson's ratio of the strata above the tunnel is adjusted. Calculated by the following formula:

[0020]

[0021] In the formula, The value is Poisson's ratio of the strata above the tunnel.

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

[0023]

[0024] In the formula, FE ur,i Let be the resilient modulus of the i-th stratum at the working face; Fh n' denoted as the total thickness of the strata, and n' represents the number of strata contained in the entire working face.

[0025] Optionally, when the working face of a certain ring contains only soft soil and hard soil, then FE ur,Ⅲ , FE ur,Ⅳ Set to 0; include FE ur,Ⅲ , FE ur,Ⅳ absolute value sub-items , , , , All values ​​are set to 0, therefore the stratigraphic difference at the annular face is... FD The calculation formula is:

[0026] .

[0027] Optional, formation composite ratio at the working face FC Calculated by the following formula:

[0028]

[0029] In the formula,Fh Ⅰ The total thickness of Class I strata, which includes all lateral pressure coefficients ξ>0.43 or Poisson's ratios at the working face. Clay, sand, plain fill, fully filled karst caves, and fully weathered rock layers with a density >0.3; Fh Ⅱ The total thickness of Class II strata, which includes all lateral pressure coefficients ξ < 0.43 and Poisson's ratios in the tunnel face. <0.3 clay, sand, plain fill, fully filled karst caves, fully weathered rock layers, and gravel and pebbles; Fh Ⅲ This represents the total thickness of Class III strata, which includes all types of strongly weathered rock layers at the tunnel face. Fh Ⅳ This represents the total thickness of Class IV strata, which includes all types of moderately weathered rock layers at the working face.

[0030] Optional, number of layers at the working face FN for Fh Ⅰ , Fh Ⅱ , Fh Ⅲ , Fh Ⅳ The number of variables that are not zero.

[0031] Optional, stratigraphic variability at the working face FD Calculated by the following formula:

[0032]

[0033] In the formula, FE ur,Ⅰ The comprehensive resilient modulus of Class I strata is obtained by weighting the resilient modulus of each Class I stratum by thickness. FE ur,Ⅱ The comprehensive resilient modulus of Class II strata is obtained by weighting the resilient modulus of each Class II stratum by thickness. FE ur,Ⅲ The comprehensive resilient modulus of Class III strata is obtained by weighting the resilient modulus of each Class III stratum by thickness. FE ur,Ⅳ The overall resilient modulus of Class IV strata is obtained by weighting the resilient modulus of each Class IV stratum by thickness.

[0034] Compared with the prior art, the beneficial effects of this invention are as follows:

[0035] 1. This invention, based on the spatial distribution of strata, proposes six indicators to characterize the strata surrounding the tunnel, including: the corrected resilient modulus of the strata above the tunnel. Corrected Poisson's ratio with the strata above the tunnel Two parameters are used to characterize the comprehensive properties of the strata above the tunnel; the weighted resilient modulus of the strata at the tunnel face. FE ur Structural variation at the working face FD Formation composite ratio at the working face FC Number of layers at the working face FN The four parameters are used to characterize the location of the tunnel, that is, the comprehensive properties of the strata at the location of the cutterhead face when the tunnel boring machine is excavating. The values ​​of the six indicators can accurately and quantitatively reflect the degree of influence of the strata distribution when the tunnel boring machine is excavating at various locations.

[0036] 2. This invention innovatively uses the resilient modulus combined with a correction method specifically designed for different strata types to unify the evaluation index of the properties of various strata, from soft soil to hard soil to rock, in tunnel construction.

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

[0038] 4. In addition to weighted correction based on thickness and depth, the present invention introduces a normalized correction factor index to eliminate calculation errors introduced during mathematical operations for the correction method of the strata above the tunnel, which has a clear meaning of spatial physical information.

[0039] 5. In addition to characterizing the strata above the tunnel, this invention also provides a refined characterization of the strata at the tunnel face. Besides focusing on the comprehensive resilient modulus of the strata at the tunnel face, it also focuses on the degree of difference in the strata at the tunnel face. This is used to assess and characterize the soft and hard composite strata with extremely high risk in engineering projects. It precisely represents the differences, degree of compositeness, and number of strata types in each stratum at the tunnel face, and realizes a quantitative assessment of construction risks. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. 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 effort, wherein:

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

[0042] Figure 2 This is a schematic diagram of the geological strata distribution at the tunnel face provided by the present invention. Detailed Implementation

[0043] The technical solutions of this invention will now be clearly and completely described in conjunction with the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] This invention provides a method for characterizing the strata surrounding a tunnel that is rich in spatial physical information, characterized by comprising the following steps:

[0045] Step S1: Calculate the resilient modulus of each stratum in the cross section where the tunnel ring is located;

[0046] Step S2: Calculate the corrected resilient modulus of the strata above the tunnel at the cross-section using the normalized stratum depth and thickness correction method. Corrected Poisson's ratio of the strata above the tunnel And the resilient modulus was corrected using the strata above the tunnel. Corrected Poisson's ratio with the strata above the tunnel Two parameters characterize the combined properties of the strata above the tunnel;

[0047] Step S3: Calculate the weighted resilient modulus of the formation at the tunnel face. FE ur Structural variation at the working face FD Formation composite ratio at the working face FC Number of layers at the working face FN and the weighted resilient modulus of the formation at the working face FE ur Structural variation at the working face FD Formation composite ratio at the working face FC Number of layers at the working face FN The four parameters characterize the comprehensive properties of the strata at the location of the cutterhead face (i.e., the location of the tunnel) during tunnel boring machine excavation.

[0048] In step S1, the resilient modulus of each stratum in the cross section corresponding to the tunnel ring is... Calculated by the following formula:

[0049]

[0050] In the formula, The unloading and reloading modulus under the reference confining pressure was measured in a triaxial consolidated drained loading and unloading test. c、 φ The effective cohesion and effective internal friction angle were measured under triaxial consolidated drained or undrained tests, respectively. p ref For reference confining pressure; The minimum principal stress can be taken as the static horizontal earth pressure σ0 without considering the overhead load and soil arching effect; m is the stiffness stress level related power exponent measured by the triaxial consolidated drained test or standard consolidated test.

[0051] It should be noted that because the strata 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 strata distribution of the corresponding section of the ring.

[0052] When only geological survey reports can serve as a reference for the physical and mechanical properties of the formation, the resilient modulus The parameters in the calculation formula can be calculated according to the following principles: For moderately weathered rocks, the elastic modulus is directly taken as the resilient modulus. For other types of strata, c, φ The average value of triaxial or direct shear tests can be used; for soft soil, completely weathered rock strata, and fully filled karst caves, only the compression modulus corresponding to 100–200 kPa in the consolidation test is usually given. E 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 taken as 0.75; when E s1-2 >18:00, Take 3 times E s1-2 m is 0.6; when E s1-2 When the value is in the middle, linear interpolation is performed; for dense sand, gravel, pebbles, and strongly weathered rock, the formula is used. Calculate the compressive 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.

[0053] In step S2, combined Figure 1 As shown, the corrected resilient modulus of the strata above the tunnel Calculated by the following formula:

[0054]

[0055] In the formula, E ur,iLet i be the resilient modulus of the i-th stratum; This is the normalized depth-thickness correction factor, calculated by the following formula:

[0056]

[0057] In the formula, t i For the first i The thickness of each stratum; h i For the first i The burial depth of each stratum; h For tunnel burial depth; This is a thickness correction factor; This is a depth correction factor.

[0058] Corrected Poisson's ratio of the strata above the tunnel Calculated by the following formula:

[0059]

[0060] In the formula, The value is Poisson's ratio of the strata above the tunnel.

[0061] In step S3, combined Figure 2 As shown, the weighted resilient modulus of the formation at the working face. FE ur Calculated by the following formula:

[0062]

[0063] In the formula, FE ur,i Let be the resilient modulus of the i-th stratum at the working face; Fh n' denoted as the total thickness of the strata, and n' represents the number of strata contained in the entire working face.

[0064] It is important to note that when calculating the stratigraphic variation at the face of a particular ring... FD When only the stratigraphic type present in the tunnel face needs to be considered, the stratigraphic difference at the tunnel face is considered when a certain type of stratigraphic type is not present. FD In the calculation formula, the weighted resilient modulus corresponding to non-existent strata in the denominator is set to 0, and all absolute value sub-items in the numerator that contain the weighted resilient modulus of non-existent strata are set to 0. For example, when the face of a certain ring only contains soft soil and hard soil, then the denominator... FE ur,Ⅲ , FE ur,Ⅳ Set to 0; the molecule contains FE ur,Ⅲ , FE ur,Ⅳ absolute value sub-items , , , , All values ​​are set to 0, therefore the stratigraphic difference at the annular face is... FD The calculation formula is:

[0065] .

[0066] Formation composite ratio at the working face FC Calculated by the following formula:

[0067]

[0068] In the formula, Fh Ⅰ The total thickness of Class I strata, which includes all lateral pressure coefficients ξ>0.43 or Poisson's ratios at the working face. Clay, sand, plain fill, fully filled karst caves, and fully weathered rock layers with a density >0.3; Fh Ⅱ The total thickness of Class II strata, which includes all lateral pressure coefficients ξ < 0.43 and Poisson's ratios in the tunnel face. <0.3 clay, sand, plain fill, fully filled karst caves, fully weathered rock layers, and gravel and pebbles; Fh Ⅲ This represents the total thickness of Class III strata, which includes all types of strongly weathered rock layers at the tunnel face. Fh Ⅳ This represents the total thickness of Class IV strata, which includes all types of moderately weathered rock layers at the working face.

[0069] Number of layers at the working face FN for Fh Ⅰ , Fh Ⅱ , Fh Ⅲ , Fh Ⅳ The number of variables that are not zero.

[0070] Stratigraphic variability at the working face FD Calculated by the following formula:

[0071]

[0072] In the formula, FE ur,Ⅰ The comprehensive resilient modulus of Class I strata is obtained by weighting the resilient modulus of each Class I stratum by thickness. FE ur,Ⅱ The comprehensive resilient modulus of Class II strata is obtained by weighting the resilient modulus of each Class II stratum by thickness.FE ur,Ⅲ The comprehensive resilient modulus of Class III strata is obtained by weighting the resilient modulus of each Class III stratum by thickness. FE ur,Ⅳ The overall resilient modulus of Class IV strata is obtained by weighting the resilient modulus of each Class IV stratum by thickness.

[0073] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0074] Furthermore, 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, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than 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 have been described above. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A method for characterizing the strata surrounding a tunnel rich in spatial physical information, characterized in that, Includes the following steps: Step S1: Calculate the resilient modulus of each stratum in the cross section where the tunnel ring is located; Step S2: Calculate the corrected resilient modulus of the strata above the tunnel at the cross-section using the normalized stratum depth and thickness correction method. Corrected Poisson's ratio of the strata above the tunnel And the resilient modulus was corrected using the strata above the tunnel. Corrected Poisson's ratio with the strata above the tunnel Two parameters characterize the combined properties of the strata above the tunnel; Step S3: Calculate the weighted resilient modulus of the formation at the tunnel face. Structural variation at the working face FD Formation composite ratio at the working face FC Number of layers at the working face FN and the weighted resilient modulus of the formation at the working face Structural variation at the working face FD Formation composite ratio at the working face FC Number of layers at the working face FN Four parameters characterize the comprehensive properties of the strata at the location of the cutterhead face during tunnel boring machine (TBM) excavation; when the face of a certain ring contains only soft soil and hard soil, then... , Set to 0; include , absolute value sub-items , , , , All values ​​are set to 0, therefore the stratigraphic difference at the annular face is... FD The calculation formula is: In the formula, The comprehensive resilient modulus of Class I strata is obtained by weighting the resilient modulus of each Class I stratum by thickness. The comprehensive resilient modulus of Class II strata is obtained by weighting the resilient modulus of each Class II stratum by thickness. The comprehensive resilient modulus of Class III strata is obtained by weighting the resilient modulus of each Class III stratum by thickness. The comprehensive resilient modulus of Class IV strata is obtained by weighting the resilient modulus of each Class IV stratum by thickness. Formation composite ratio at the working face FC Calculated by the following formula: In the formula, The total thickness of Class I strata, which includes all lateral pressure coefficients ξ>0.43 or Poisson's ratios at the working face. Clay, sand, plain fill, fully filled karst caves, and fully weathered rock layers with a density >0.3; The total thickness of Class II strata, which includes all lateral pressure coefficients ξ < 0.43 and Poisson's ratios in the tunnel face. <0.3 clay, sand, plain fill, fully filled karst caves, fully weathered rock layers, and gravel and pebbles; This represents the total thickness of Class III strata, which includes all types of strongly weathered rock layers at the tunnel face. This represents the total thickness of Class IV strata, which includes all types of moderately weathered rock layers at the working face.

2. The method according to claim 1, characterized in that, In step S1, the resilient modulus of each stratum in the cross section corresponding to the tunnel ring is... Calculated by the following formula: In the formula, The unloading and reloading modulus under the reference confining pressure was measured in a triaxial consolidated drained loading and unloading test. c, φ The effective cohesion and effective internal friction angle were measured under triaxial consolidated drained or undrained tests, respectively. p ref For reference confining pressure; The minimum principal stress is taken as the static horizontal earth pressure σ0 without considering the overhead load and soil arching effect; m is the stiffness stress level related power exponent measured by the triaxial consolidated drained test or standard consolidated test.

3. The method according to claim 2, characterized in that, For moderately weathered rocks, the elastic modulus is directly taken as the resilient modulus. For other types of strata, c, φ Take the average value of triaxial or direct shear tests; for soft soil, completely weathered rock layers, and fully filled karst caves, 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 taken as 0.75; when E s1-2 >18:00, Take 3 times E s1-2 m is 0.6; when E s1-2 When the value is in the middle, linear interpolation is performed; for dense sand, gravel, pebbles, and strongly weathered rock, the formula is used. Calculate the compressive 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 resilient modulus of the strata above the tunnel is corrected. Calculated by the following formula: In the formula, E ur,i Let i be the resilient modulus of the i-th stratum; This is the normalized depth-thickness correction factor, calculated by the following formula: In the formula, t i For the first i The thickness of each stratum; h i For the first i The burial depth of each stratum; h For tunnel burial depth; This is a thickness correction factor; This is a depth correction factor.

5. The method according to claim 4, characterized in that, Corrected Poisson's ratio of the strata above the tunnel Calculated by the following formula: In the formula, The value is Poisson's ratio of the strata above the tunnel.

6. The method according to claim 5, characterized in that, Weighted resilient modulus of the formation at the working face Calculated by the following formula: In the formula, For the first face The resilient modulus of each stratum; The total thickness of the strata. This indicates the number of strata contained in the entire working face.

7. The method according to claim 6, characterized in that, Number of layers at the working face FN for , , , The number of variables that are not zero.

8. The method according to claim 7, characterized in that, Stratigraphic variability at the working face FD Calculated by the following formula: 。

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