In the functionality related to tunnel overexcavation and other tasks requiring the use of tunnel cross-sections, manually selecting each cross-section is tedious and time-consuming. Therefore, the software provides a feature for matching tunnel cross-sections with mileages. By inputting the cross-section mileage match, the software automatically locates the matched cross-sections for calculation. Excavation, primary support, and secondary lining each have their independent cross-section mileage matching parameters.

• Tunnel Cross Section Library: Functions as a collection of cross-section templates. The role of cross-section mileage matching parameters is to map these templates onto mileages.
• Starting Mileage: The starting mileage of the selected cross-section matching interval or the mileage of the starting cross-section in case of a cross-section gradient.
• Cross-Section Sudden: Indicates a mutation between this cross-section and the subsequent one. That is, both the starting mileage and the next starting mileage belong to this cross-section. This is a common variation form.
• Cross-Section Gradual: Indicates a gradient between this cross-section and the subsequent one. That is, the cross-sections between the starting mileage and the next starting mileage transition gradually from this cross-section to the next one (trumpet shape).
• Modify: Click on the cross-section mileage match to be modified, make direct edits, and save.
• Insert: Click on 'Create New Cross-Section Mileage Match,' input the mileage, choose the cross-section. The software will automatically determine if insertion is necessary based on the input mileage and provide prompts. In this software, cross-section mileage matching must be arranged in ascending order.
• Delete: Click on the delete button in front of the cross-section mileage match.

The logic for finding the required cross-section based on known mileage, in descending order of priority:

1. If the cross-section library for the selected cross-section type is empty, an error is prompted, and the calculation is abandoned.
2. In the case of manually selecting cross-sections, the selected cross-sections will participate in the calculation.
3. In the case of automatic matching, if the cross-section library for the selected cross-section type contains only one cross-section, regardless of whether the cross-section mileage matching list has matches or whether matches are successful, select this cross-section for calculation.
4. In the case of automatic matching, if the cross-section library for the selected cross-section type contains multiple cross-sections, find the matching cross-section according to the following rules:
   • Before the first matching mileage, take the first matching cross-section for calculation.
   • After the last matching mileage, take the last matching cross-section for calculation.
   • Between two matching mileages, based on the change mode:
     • Mutation (common): Select the cross-section matching the previous one for calculation.
     • Gradient: Use the previous cross-section as the starting cross-section and the next one as the ending cross-section. The program calculates overexcavation twice between these two cross-sections and then linearly calculates the final overexcavation values based on the previous and subsequent mileages and the current mileage. For example, at the start: lateral -4, vertical 6, over 4, and at the end: lateral -2, vertical 4, over 2. When the known mileage is the middle mileage, the final overexcavation result is lateral -3, vertical 5, over 3.

Due to the diverse forms of tunnel cross-sections, if the change mode is gradient, some cross-sections may be calculated incorrectly. It is recommended to watch relevant videos to understand tunnel cross-section forms that support gradient calculations.