Novel method for selecting main support parameters of road drilling and blasting tunnel

Abstract

The invention relates to a method for selecting support parameters of a drilling and blasting tunnel, which specifically comprises the following steps of: calculating primary support and secondary lining thicknesses of different lane numbers and different surrounding rock levels of the road drilling and blasting tunnel by selecting a contract formula, and giving a constant value involved in the formula;

Description

Technical Field

[0001] This invention relates to a method for selecting support parameters for drill-and-blast tunnels, specifically by using formulas to select the initial support and secondary lining thicknesses for different numbers of lanes and different surrounding rock grades in drill-and-blast highway tunnels. Background Technology

[0002] Currently, the selection of support parameters for drill-and-blast tunnels with three lanes or less is mainly based on given support parameters, without addressing the selection of support parameters for tunnels with more than three lanes, especially the selection of initial support and secondary lining thickness for surrounding rock grades II, III, and IV. With economic development, the number of tunnels with more than three lanes is gradually increasing, and there is a lack of an effective and universal method. Summary of the Invention

[0003] The purpose of this invention is to provide a general method for selecting the thickness of the primary support and secondary lining for lanes of 3 or more, in order to solve the problems mentioned above.

[0004] To address the aforementioned problems, this invention provides the following technical method: A general formula is selected, and the constant values ​​y0, A1, and t1 of the formula are chosen according to different surrounding rock grades (II, III, IV). The number of lanes x (considering a single lane width of 3.75 meters) is input to calculate the thickness values ​​y of the primary support and secondary lining. Based on the surrounding rock quality tolerance, the values ​​of the primary support and secondary lining should fluctuate by 20% above or below y.

[0005] The formula selected for the calculation results is:

[0006] The constant values ​​in the formula are taken from the table below.

[0007] For lanes of 4 or fewer, the actual value x can be used.

[0008] For lanes with four or more lanes, x needs to be reduced. The reduction formula is x = x' + (x' - 4) × 0.5. Enter x into the formula to calculate y.

[0009] The final primary support and secondary lining thicknesses are selected within 20% of y. Attached Figure Description

[0010] 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. The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation of the present invention.

[0011] Appendix Figure 1 This is a schematic diagram of the lining structure.

[0012] Explanation of reference numerals in the attached drawings: 1. Secondary lining; 2. Initial support; 3. Waterproof membrane; 4. System anchor bolt; 5. Vehicle design clearance. Detailed Implementation

[0013] The width of a lane is 3.75 meters. The number of lanes x' is selected according to the design requirements.

[0014] To determine whether x is greater than 4 or less than or equal to 4, if x is greater than 4, x = x' + (x' - 4) × 0.5; if x is less than 4, x = x'.

[0015] Substitute x into the formula and select the constants yo, A1, and t1 for calculating the primary support or secondary lining according to different surrounding rock grades (II, III, IV).

[0016] Substitute into the formula to calculate y.

[0017] Calculate the range of y with a fluctuation of 20% above and below: y×(1-20%) and y×(1+20%).

[0018] The thickness of the primary support and secondary lining is selected from the range of y×(1-20%) to y×(1+20%) based on the quality of the surrounding rock.

Claims

1. This invention relates to a method for selecting support parameters for drill-and-blast tunnels, characterized in that: The formula is used to select the initial support and secondary lining thicknesses for different numbers of lanes and different surrounding rock grades in highway drill-blast tunnels.

2. The method as claimed in claim 1, characterized in that: The thickness of the primary support and secondary lining is selected using a formula.

3. The method as claimed in claim 1, characterized in that: Formula selected 4. The method as claimed in claim 1, characterized in that: The constant values ​​y0, A1, and t1 in the formula should be selected from the following values.

5. The method as claimed in claim 1, characterized in that: In this method, for lanes of 4 or fewer, the actual value x can be used; for lanes of more than 4, x needs to be reduced, and the reduction formula is x = x' + (x' - 4) × 0.

5.

6. The method as claimed in claim 1, characterized in that: The final primary support and secondary lining thicknesses are selected within 20% of y.

7. The method as claimed in claim 1, characterized in that: This method is applicable to Class II, III, and IV surrounding rock.

8. The method as claimed in claim 1, characterized in that: This method is applicable to highway tunnels with different numbers of lanes using the drill-and-blast method.

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