A method for calculating overbreakage rate caused by overbreak and rebound of composite lining tunnel

Abstract

The application discloses a composite lining tunnel overbreak and rebound caused overconsumption rate calculation method, and has the steps as follows: tunnel shotcrete outer circumference P, inner circumference E, thickness T 喷砼 , shotcrete amount M 喷砼 is calculated; shotcrete rebound rate h, shotcrete rebound amount M 回弹 is calculated; tunnel secondary lining outer circumference E, inner circumference F, thickness T 二衬 , tunnel secondary lining concrete amount M 二衬 is calculated; tunnel shotcrete outer circumference E, reserved deformation Y, tunnel reserved deformation amount M 预留 is calculated; tunnel inverted arch length D, average linear overbreak value b, tunnel inverted arch overbreak amount M 仰拱超挖 is calculated; tunnel shotcrete design outer circumference P, average linear overbreak value b, tunnel arch wall overbreak amount M 拱墙超挖 is calculated; tunnel shotcrete and secondary lining comprehensive overconsumption rate C 综合 is calculated.The application considers the overconsumption rate caused by tunnel overbreak and rebound, and the calculation result is more in line with the actual overconsumption rate on site.

Description

Technical Field

[0001] This invention relates to the field of over-excavation control in tunnel engineering, and more specifically, to a method for calculating the over-excavation rate caused by over-excavation and rebound in composite lining tunnels. Background Technology

[0002] China Railway alone has approximately 3,000 km of tunnels under construction, with a contract value exceeding 1 trillion yuan. Furthermore, my country plans to construct at least 22,000 km of tunnels, with a market size exceeding 7 trillion yuan. Major projects such as the Xinjiang-Tibet Railway, the Yunnan-Tibet Railway, and the Qingdao Second Tunnel are particularly reliant on the drill-and-blast method. However, tunnel excavation is often hampered by factors such as a shortage of experienced on-site geological engineers, mismatched performance of drilling and shotcrete equipment, unstable raw materials and mix proportions of shotcrete, and poor construction techniques. These factors lead to over-excavation and shotcrete rebound, affecting structural stress, construction safety, increasing costs, and reducing efficiency.

[0003] The standard "Railway Engineering Budget Quota, Volume 3: Tunnel Engineering" (2017 edition) stipulates that factors such as reserved deformation and over-excavation backfilling are not considered in the quota. According to the railway budget preparation method, the design unit shall consider them in the construction drawings based on the specific circumstances and include them under the shotcrete item in the contract list. However, current regulations and standards do not specify the calculation method for the excess consumption rate caused by tunnel over-excavation and rebound. This leads to a mismatch between the cost system, such as the excavation unit price and the shotcrete unit price, and the actual consumption, which directly affects the project investment. Therefore, the reasonable calculation of the excess consumption rate caused by tunnel over-excavation and rebound is a problem that we must solve.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] The technical problem this invention aims to solve is that existing tunnel engineering budgets do not include a method for calculating the over-consumption rate of concrete caused by tunnel over-excavation and rebound, resulting in discrepancies between preliminary calculations and actual over-consumption rates. The invention provides a method for calculating the over-consumption rate caused by over-excavation and rebound in composite-lined tunnels, offering a simple and feasible formula that considers the over-consumption rate caused by tunnel over-excavation and rebound. The calculated results better reflect the actual over-consumption rate on site, resolving the mismatch between tunnel excavation and shotcrete unit prices and on-site conditions. This leads to more accurate preliminary cost estimates and improves the accuracy of project investment preparation results.

[0006] This invention is achieved through the following technical solution:

[0007] A method for calculating the excess wear rate caused by over-excavation and rebound in composite lining tunnels includes the following steps:

[0008] 1) Calculate the design excavation volume M of the tunnel per unit length. 设计 =S设计 ×ρ 围岩 ;

[0009] 2) The outer perimeter of the shotcrete design for the tunnel is P, the inner perimeter is E, and the design thickness of the shotcrete is T. 喷砼 Calculate the amount of shotcrete per unit length of tunnel, M. 喷砼 = (P+E) / 2×T 喷砼 ×ρ 喷砼 ;

[0010] 3) The rebound rate of shotcrete is h, and the rebound amount of shotcrete is M. 回弹 =M 喷砼 ×h=(P+E) / 2×T 喷砼 ×ρ 喷砼 ×h;

[0011] 4) The outer perimeter of the tunnel secondary lining is E, the inner perimeter is F, and the design thickness of the secondary lining is T. 二衬 Calculate the amount of secondary lining concrete per unit length of tunnel, M. 二衬 = (E+F) / 2×T 二衬 ×ρ 二衬 ;

[0012] 5) The perimeter of the tunnel shotcrete design is E, and the allowable deformation is Y. Half of the allowable deformation is achieved through secondary lining backfill. Calculate the allowable deformation M per unit length of tunnel. 预留 =E×Y / 2×ρ 二衬 ;

[0013] 6) Given a tunnel invert or floor slab design length of D and an average over-excavation value of b, calculate the over-excavation amount M per unit length of tunnel invert. 仰拱超挖 =D×b×ρ 二衬 ;

[0014] 7) Given that the perimeter of the tunnel shotcrete design is P and the average over-excavation value is b, calculate the over-excavation amount M per unit length of the tunnel arch wall. 拱墙超挖 =P×b×ρ 喷砼 ;

[0015] 8) Calculate the excess consumption rate C of shotcrete per unit length of tunnel. 喷砼 =(M 回弹 +M 拱墙超挖 ) / M 喷砼 Excessive wear rate C of secondary lining per unit length of tunnel 二衬 =(M 预留 +M 仰拱超挖 ) / M 二衬 The combined excess consumption rate of shotcrete and secondary lining per unit length of tunnel C 综合 =(M 回弹 +M 拱墙超挖+ M预留 +M 仰拱超挖 ) / (M 喷砼 +M 二衬 ).

[0016] This invention provides a calculation formula that is simple and feasible. It takes into account the over-excavation rate caused by tunnel over-excavation and rebound, and the calculation results can better match the actual over-excavation rate on site. This solves the problem of mismatch between the unit price of tunnel excavation and shotcrete and the actual site conditions, making the preliminary cost budget more accurate and improving the accuracy of the project investment preparation results.

[0017] Furthermore, the calculation steps for the average linear overcut value b are as follows:

[0018] 1) Collect data on the surrounding rock grade, degree of rock fragmentation, and actual average over-excavation value of multiple tunnels that have been completed, excavated, or are under construction;

[0019] 2) Establish the mapping relationship between the surrounding rock grade and the degree of surrounding rock fragmentation and the actual average over-excavation value of the alignment;

[0020] 3) Obtain the surrounding rock grade and the degree of surrounding rock fracture of the tunnel, and obtain the average over-excavation value b based on the mapping relationship.

[0021] This invention collects the surrounding rock grade and degree of fracture in existing tunnel construction and their corresponding actual average over-excavation value, and processes the data to use as the average over-excavation value b in the tunnel calculation formula. This makes the theoretically calculated value b as close as possible to the actual average over-excavation value of the tunnel in subsequent actual construction, thereby making the calculation result of the over-excavation rate more accurate.

[0022] Furthermore, the specific method for step 2) is as follows:

[0023] a. The actual average over-excavation value of each tunnel is weighted and calculated with the average over-excavation control value of the tunnel corresponding to the surrounding rock grade and degree of fracture to obtain the corrected actual average over-excavation value of the tunnel. The weighting ratio of the actual average over-excavation value to the average over-excavation control value is 9:1.

[0024] b. Add the corrected actual average over-excavation values ​​of tunnels of the same surrounding rock grade and calculate the average value to obtain the average over-excavation value b of the tunnel of that surrounding rock grade.

[0025] This invention performs a weighted calculation of the actual average over-excavation value of existing tunnels and the standard average over-excavation control value of tunnels. This can correct the differences in the actual average over-excavation value caused by the specific characteristics of different tunnels, making the actual average over-excavation value more consistent with that of conventional tunnels.

[0026] Furthermore, in step b, data where the difference between the corrected actual average over-excavation value and the calculated average value is greater than 20% are removed, and the remaining data are summed to calculate the average value.

[0027] This invention further eliminates the over-excavation values ​​of the actual average alignment that are significantly different, making the calculation results closer to the actual construction situation and improving the consistency between the calculation results and the actual losses on site.

[0028] Furthermore, the surrounding rock grade, degree of fracturing, and corresponding average linear over-excavation control values ​​are as follows:

[0029] Class I surrounding rock, intact, with an average linear over-excavation control value of 10cm;

[0030] Class II surrounding rock, relatively intact, with an average linear over-excavation control value of 12cm;

[0031] Class III surrounding rock, relatively broken, with an average linear over-excavation control value of 13cm;

[0032] Class IV surrounding rock, fractured, with an average linear over-excavation control value of 15cm;

[0033] Class V surrounding rock, extremely broken, with an average linear over-excavation control value of 10cm.

[0034] Furthermore, the design thickness T of the shotcrete 喷砼 Positively correlated with the surrounding rock grade of the tunnel, T 喷砼 The value range is 8 to 30 cm.

[0035] Furthermore, the secondary lining design thickness T 二衬 Positively correlated with the surrounding rock grade of the tunnel, T 二衬 The value range is 35 to 55 cm.

[0036] Furthermore, the allowable deformation is positively correlated with the grade of the surrounding rock of the tunnel, and the allowable deformation range is 2 to 15 cm.

[0037] Furthermore, the method for detecting the actual average over-excavation value of the tunnel in step 1) is as follows:

[0038] Obtain measured point cloud data of the tunnel cross-section;

[0039] Calculate the over-excavation area of ​​the tunnel cross-section;

[0040] The actual average linear over-excavation value of the tunnel cross-section is obtained by comparing the over-excavation area of ​​the cross-section with the arc length corresponding to the central angle of the measured point cloud profile of the cross-section on the design profile.

[0041] Furthermore, the over-excavation area of ​​different parts of the cross-section is calculated separately, namely the arch, sidewall, and invert arch;

[0042] Then, the ratio of the over-excavation area of ​​different parts to the arc length corresponding to the central angle of the cloud contour of that part on the design contour is used to obtain the local average linear over-excavation value of different parts.

[0043] Finally, the local average linear over-excavation value is weighted according to the proportion of over-excavation area in different parts to obtain the actual average linear over-excavation value.

[0044] This invention calculates the over-excavation value separately for different parts of the tunnel cross-section and then performs a weighted calculation, which makes the detection value of the actual average linear over-excavation value of the constructed tunnel more accurate, so as to provide a more applicable average linear over-excavation value for the calculation formula of this invention.

[0045] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0046] 1. The present invention provides a method for calculating the over-excavation and rebound rate of composite lining tunnels, and gives a calculation formula. The formula is simple and feasible, takes into account the over-excavation and rebound rate of the tunnel, and the calculation result can better match the actual over-excavation rate on site. It solves the problem of mismatch between the unit price of tunnel excavation and shotcrete and the site, and makes the early cost budget more accurate, thereby improving the accuracy of the project investment preparation results.

[0047] 2. The present invention provides a method for calculating the over-excavation rate caused by over-excavation and rebound in composite lining tunnels. By collecting the surrounding rock grade and degree of fracture and the corresponding actual average over-excavation value in the existing tunnel construction and processing the data, the average over-excavation value b in the tunnel calculation formula is used. This makes the theoretically calculated value b as close as possible to the actual average over-excavation value of the tunnel in the subsequent actual construction, thereby making the calculation result of the over-excavation rate more accurate.

[0048] 3. The present invention provides a method for calculating the over-excavation rate caused by over-excavation and rebound in composite lining tunnels. This method weights the actual average over-excavation value of existing tunnels with the standard average over-excavation control value, which can correct the differences in the actual average over-excavation value caused by the specificity of different tunnels. This makes the actual average over-excavation value more consistent with that of conventional tunnels. In addition, it further eliminates the actual average over-excavation value data with significantly different values, making the calculation results closer to the actual construction situation and improving the consistency between the calculation results and the actual losses on site. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a diagram of a tunnel over-excavation / under-excavation structure provided in an embodiment of the present invention;

[0051] Figure 2 The distribution diagram of over-excavation of tunnel arch walls and over-excavation of invert arches provided in the embodiments of the present invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0053] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known methods have not been specifically described in order to avoid obscuring the invention.

[0054] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination.

[0055] Example 1

[0056] like Figure 1 and Figure 2 As shown in the figure, the present invention provides a method for calculating the over-excavation rate caused by over-excavation and rebound in composite lining tunnels, comprising the following steps:

[0057] 1) Calculate the design excavation volume M of the tunnel per unit length. 设计 =S 设计 ×ρ 围岩 ;

[0058] 2) The outer perimeter of the shotcrete design for the tunnel is P, the inner perimeter is E, and the design thickness of the shotcrete is T.喷砼 Calculate the amount of shotcrete per unit length of tunnel, M. 喷砼 = (P+E) / 2×T 喷砼 ×ρ 喷砼 That is, the quality of the shotcrete enclosed by lines A and C;

[0059] 3) The rebound rate of shotcrete is h, and the rebound amount of shotcrete is M. 回弹 =M 喷砼 ×h=(P+E) / 2×T 喷砼 ×ρ 喷砼 ×h;

[0060] 4) The outer perimeter of the tunnel secondary lining is E, the inner perimeter is F, and the design thickness of the secondary lining is T. 二衬 Calculate the amount of secondary lining concrete per unit length of tunnel, M. 二衬 = (E+F) / 2×T 二衬 ×ρ 二衬 That is, the quality of the secondary lining enclosed by lines C and D;

[0061] 5) The perimeter of the tunnel shotcrete design is E, and the allowable deformation is Y. Half of the allowable deformation is achieved through secondary lining backfill. Calculate the allowable deformation M per unit length of tunnel. 预留 =E×Y / 2×ρ 二衬 That is, the mass enclosed by lines A and B;

[0062] 6) Given a tunnel invert or floor slab design length of D and an average over-excavation value of b, calculate the over-excavation amount M per unit length of tunnel invert. 仰拱超挖 =D×b×ρ 二衬 That is, the over-excavation quality of the lower half enclosed by the actual excavation line and line B;

[0063] 7) Given that the perimeter of the tunnel shotcrete design is P and the average over-excavation value is b, calculate the over-excavation amount M per unit length of the tunnel arch wall. 拱墙超挖 =P×b×ρ 喷砼 That is, the over-excavation quality of the upper half enclosed by the actual excavation line and line B;

[0064] 8) Calculate the excess consumption rate C of shotcrete per unit length of tunnel. 喷砼 =(M 回弹 +M 拱墙超挖 ) / M 喷砼 Excessive wear rate C of secondary lining per unit length of tunnel 二衬 =(M 预留 +M 仰拱超挖 ) / M 二衬 The combined excess consumption rate of shotcrete and secondary lining per unit length of tunnel C 综合 =(M 回弹 +M 拱墙超挖+ M预留 +M 仰拱超挖 ) / (M 喷砼 +M 二衬 ).

[0065] This invention provides a calculation formula that is simple and feasible. It takes into account the over-excavation rate caused by tunnel over-excavation and rebound, and the calculation results can better match the actual over-excavation rate on site. This solves the problem of mismatch between the unit price of tunnel excavation and shotcrete and the actual site conditions, making the preliminary cost budget more accurate and improving the accuracy of the project investment preparation results.

[0066] Furthermore, the calculation steps for the average linear overcut value b are as follows:

[0067] 1) Collect data on the surrounding rock grade, degree of rock fragmentation, and actual average over-excavation value of multiple tunnels that have been completed, excavated, or are under construction;

[0068] 2) Establish the mapping relationship between the surrounding rock grade and the degree of surrounding rock fragmentation and the actual average over-excavation value of the alignment;

[0069] 3) Obtain the surrounding rock grade and the degree of surrounding rock fracture of the tunnel, and obtain the average over-excavation value b based on the mapping relationship.

[0070] This invention collects the surrounding rock grade and degree of fracture in existing tunnel construction and their corresponding actual average over-excavation value, and processes the data to use as the average over-excavation value b in the tunnel calculation formula. This makes the theoretically calculated value b as close as possible to the actual average over-excavation value of the tunnel in subsequent actual construction, thereby making the calculation result of the over-excavation rate more accurate.

[0071] Furthermore, the specific method for step 2) is as follows:

[0072] a. The actual average over-excavation value of each tunnel is weighted and calculated with the average over-excavation control value of the tunnel corresponding to the surrounding rock grade and degree of fracture to obtain the corrected actual average over-excavation value of the tunnel. The weighting ratio of the actual average over-excavation value to the average over-excavation control value is 9:1.

[0073] b. Add the corrected actual average over-excavation values ​​of tunnels of the same surrounding rock grade and calculate the average value to obtain the average over-excavation value b of the tunnel of that surrounding rock grade.

[0074] This invention performs a weighted calculation of the actual average over-excavation value of existing tunnels and the standard average over-excavation control value of tunnels. This can correct the differences in the actual average over-excavation value caused by the specific characteristics of different tunnels, making the actual average over-excavation value more consistent with that of conventional tunnels.

[0075] Furthermore, in step b, data where the difference between the corrected actual average over-excavation value and the calculated average value is greater than 20% are removed, and the remaining data are summed to calculate the average value.

[0076] This invention further eliminates the over-excavation values ​​of the actual average alignment that are significantly different, making the calculation results closer to the actual construction situation and improving the consistency between the calculation results and the actual losses on site.

[0077] Furthermore, the surrounding rock grade, degree of fracturing, and corresponding average linear over-excavation control values ​​are as follows:

[0078] Class I surrounding rock, intact, with an average linear over-excavation control value of 10cm;

[0079] Class II surrounding rock, relatively intact, with an average linear over-excavation control value of 12cm;

[0080] Class III surrounding rock, relatively broken, with an average linear over-excavation control value of 13cm;

[0081] Class IV surrounding rock, fractured, with an average linear over-excavation control value of 15cm;

[0082] Class V surrounding rock, extremely broken, with an average linear over-excavation control value of 10cm.

[0083] Furthermore, the design thickness T of the shotcrete 喷砼 Positively correlated with the surrounding rock grade of the tunnel, T 喷砼 The value range is 8 to 30 cm.

[0084] Furthermore, the secondary lining design thickness T 二衬 Positively correlated with the surrounding rock grade of the tunnel, T 二衬 The value range is 35 to 55 cm.

[0085] Furthermore, the allowable deformation is positively correlated with the grade of the surrounding rock of the tunnel, and the allowable deformation range is 2 to 15 cm.

[0086] Furthermore, the method for detecting the actual average over-excavation value of the tunnel in step 1) is as follows:

[0087] Obtain measured point cloud data of the tunnel cross-section;

[0088] Calculate the over-excavation area of ​​the tunnel cross-section;

[0089] The actual average linear over-excavation value of the tunnel cross-section is obtained by comparing the over-excavation area of ​​the cross-section with the arc length corresponding to the central angle of the measured point cloud profile of the cross-section on the design profile.

[0090] Furthermore, the over-excavation area of ​​different parts of the cross-section is calculated separately, namely the arch, sidewall, and invert arch;

[0091] Then, the ratio of the over-excavation area of ​​different parts to the arc length corresponding to the central angle of the cloud contour of that part on the design contour is used to obtain the local average linear over-excavation value of different parts.

[0092] Finally, the local average linear over-excavation value is weighted according to the proportion of over-excavation area in different parts to obtain the actual average linear over-excavation value.

[0093] This invention calculates the over-excavation value separately for different parts of the tunnel cross-section and then performs a weighted calculation, which makes the detection value of the actual average linear over-excavation value of the constructed tunnel more accurate, so as to provide a more applicable average linear over-excavation value for the calculation formula of this invention.

[0094] Example 2

[0095] Four tunnels of unit length were selected respectively to calculate the excess consumption rate according to the calculation method of the present invention, and then compared with the actual excess consumption rate of the tunnel on site.

[0096] 1. The surrounding rock grade is II. The design perimeter P of the shotcrete is 25.5m, and the design thickness T of the shotcrete is [not specified]. 喷砼 The secondary lining is 8cm thick, with a designed perimeter E of 25.1m and a designed thickness T. 二衬 The inner perimeter F of the secondary lining is 23.4m, and the design length D of the invert arch or bottom plate is 13.5m.

[0097] 2. The surrounding rock grade is III. The design perimeter P of the shotcrete is 26m, and the design thickness T of the shotcrete is [not specified]. 喷砼 The secondary lining is 10cm thick, with a designed perimeter E of 25.6m and a designed thickness T. 二衬 The inner perimeter F of the secondary lining is 35cm, the design length D of the invert arch or bottom plate is 13.8m.

[0098] 3. The surrounding rock grade is IV. The design perimeter P of the shotcrete is 26.8m, and the design thickness T of the shotcrete is [not specified]. 喷砼 The secondary lining is 24cm thick, with a designed perimeter E of 25.9m and a designed thickness T. 二衬 The inner perimeter F of the secondary lining is 45cm, the design length D of the invert arch or bottom plate is 14.33m.

[0099] 4. The surrounding rock grade is V, the design perimeter P of the shotcrete is 42.1m, and the design thickness T of the shotcrete is... 喷砼 The secondary lining is 26cm thick, with a designed perimeter E of 40.7m and a designed thickness T. 二衬 The inner perimeter F of the secondary lining is 37.5m, and the design length D of the invert arch or bottom plate is 12.5m.

[0100] Tables 1 and 2 below show the calculation methods and results of excess consumption considered in the reference specifications of the present invention and the prior art, respectively.

[0101] Table 1

[0102]

[0103] Table 2

[0104]

[0105] The results above show that this invention takes into account the over-excavation and rebound caused by tunnel over-excavation, and the result calculated by the formula is basically consistent with the actual over-excavation rate on site. However, according to the calculation formula of this invention, but with the average linear over-excavation value selected with reference to the specifications, the calculated over-excavation rate differs greatly from the actual over-excavation rate. This indicates that the calculation method and formula proposed in this invention are appropriate for calculating the tunnel over-excavation rate, which solves the problem of mismatch between the budget unit price for tunnel excavation and shotcrete and the actual site conditions, and can improve the accuracy of the project investment preparation results.

[0106] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the over-excavation and rebound rate of composite lining tunnels, characterized in that, Includes the following steps: 1) Take the unit length tunnel to calculate, calculate the tunnel design excavation amount M 设计 = S 设计 × p 围岩 ; 2) The tunnel shotcrete design has an outer perimeter P and an inner perimeter E, and a shotcrete design thickness T 喷砼 , the shotcrete amount M per unit length of the tunnel is calculated 喷砼 = (P + E) / 2 x T 喷砼 x p 喷砼 ; 3) The rebound rate of shotcrete is h, and the rebound amount of shotcrete is M. 回弹 =M 喷砼 ×h=(P+E) / 2×T 喷砼 ×ρ 喷砼 ×h; 4) The outer perimeter of the tunnel secondary lining is E, the inner perimeter is F, and the design thickness of the secondary lining is T. 二衬 Calculate the amount of secondary lining concrete per unit length of tunnel, M. 二衬 = (E+F) / 2×T 二衬 ×ρ 二衬 ; 5) The perimeter of the tunnel shotcrete design is E, and the allowable deformation is Y. Half of the allowable deformation is achieved through secondary lining backfill. Calculate the allowable deformation M per unit length of tunnel. 预留 =E×Y / 2×ρ 二衬 ; 6) Given a tunnel invert or floor slab design length of D and an average over-excavation value of b, calculate the over-excavation amount M per unit length of tunnel invert. 仰拱超挖 =D×b×ρ 二衬 ; 7) Given that the perimeter of the tunnel shotcrete design is P and the average over-excavation value is b, calculate the over-excavation amount M per unit length of the tunnel arch wall. 拱墙超挖 =P×b×ρ 喷砼 ; 8) Calculate the excess consumption rate C of shotcrete per unit length of tunnel. 喷砼 =(M 回弹 +M 拱墙超挖 ) / M 喷砼 Excessive wear rate C of secondary lining per unit length of tunnel 二衬 =(M 预留 +M 仰拱超挖 ) / M 二衬 The combined excess consumption rate of shotcrete and secondary lining per unit length of tunnel C 综合 =(M 回弹 +M 拱墙超挖+ M 预留 +M 仰拱超挖 ) / (M 喷砼 +M 二衬 ).

2. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 1, characterized in that, The calculation steps for the average linear overcut value b are as follows: 1) Collect data on the surrounding rock grade, degree of rock fragmentation, and actual average over-excavation value of multiple tunnels that have been completed, excavated, or are under construction; 2) Establish the mapping relationship between the surrounding rock grade and the degree of surrounding rock fragmentation and the actual average over-excavation value of the alignment; 3) Obtain the surrounding rock grade and the degree of surrounding rock fracture of the tunnel, and obtain the average over-excavation value b based on the mapping relationship.

3. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 2, characterized in that, The specific method for step 2) is as follows: a. The actual average over-excavation value of each tunnel is weighted and calculated with the average over-excavation control value of the tunnel corresponding to the surrounding rock grade and degree of fracture, so as to obtain the corrected actual average over-excavation value of the tunnel. b. Add the corrected actual average over-excavation values ​​of tunnels of the same surrounding rock grade and calculate the average value to obtain the average over-excavation value b of the tunnel of that surrounding rock grade.

4. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 3, characterized in that, In step b, data where the difference between the corrected actual average overcut value and the calculated average value is greater than 20% are removed, and the remaining data are summed to calculate the average value.

5. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 3, characterized in that, The surrounding rock grade, degree of fracturing, and corresponding average over-excavation control values ​​are as follows: Class I surrounding rock, intact, with an average linear over-excavation control value of 10cm; Class II surrounding rock, relatively intact, with an average linear over-excavation control value of 12cm; Class III surrounding rock, relatively broken, with an average linear over-excavation control value of 13cm; Class IV surrounding rock, fractured, with an average linear over-excavation control value of 15cm; Class V surrounding rock, extremely broken, with an average linear over-excavation control value of 10cm.

6. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 1, characterized in that, Shotcrete design thickness T 喷砼 Positively correlated with the surrounding rock grade of the tunnel, T 喷砼 The value range is 8 to 30 cm.

7. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 1, characterized in that, Secondary lining design thickness T 二衬 Positively correlated with the surrounding rock grade of the tunnel, T 二衬 The value range is 35 to 55 cm.

8. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 1, characterized in that, The allowable deformation is positively correlated with the grade of the surrounding rock of the tunnel, and the allowable deformation range is 2 to 15 cm.

9. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 2, characterized in that, The method for detecting the actual average over-excavation value of the tunnel in step 1) is as follows: Obtain measured point cloud data of the tunnel cross-section; Calculate the over-excavation area of ​​the tunnel cross-section; The actual average linear over-excavation value of the tunnel cross-section is obtained by comparing the over-excavation area of ​​the cross-section with the arc length corresponding to the central angle of the measured point cloud profile of the cross-section on the design profile.

10. The method for calculating the over-excavation and rebound rate of composite lining tunnels according to claim 9, characterized in that, Calculate the over-excavation area at different parts of the cross-section, namely the arch, sidewall, and invert. Then, the ratio of the over-excavation area of ​​different parts to the arc length corresponding to the central angle of the cloud contour of that part on the design contour is used to obtain the local average linear over-excavation value of different parts. Finally, the local average linear over-excavation value is weighted according to the proportion of over-excavation area in different parts to obtain the actual average linear over-excavation value.

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