Carinthian Cut and Cover Method

Method Overview

• In this method, the upper soil cover of the tunnel is excavated and crown arch concrete structure is constructed, and then the structure is backfilled for low soil cover section tunneling. This semi open-cut tunnel construction method for low soil cover section solves excessive slope theft in existing open-cut method and the high costs of reinforcing method, and at the same time, prevents the fall down of upper area soil cover in tunnel excavation.
• It is applicable to the area too close to residential areas, where damage to nature and civic complaints caused by vibration, noise, and dust scattering due to excavation and earthwork in open-cut tunneling are concerned or to the case in which delivering muck is hard due to surrounded conditions and the entry of heavy equipment is difficult. This method is an environmentally friendly design concept that can solve excessive slope thief using the existing open-cut method.

Open-cut method feature comparison

Open-cut method feature comparison

Type	Carinthian-Cut method	Open-Cut method	Temporary facility method
Outline
Features	Reduce around slope theft by minimizing excavation area Lower construction costs compare to temporary facility method Minimize intrusion period for existing roads Increase construction period Somewhat complicated constructability	Easy constructability Fast construction rate Low construction costs Due to increased occupying area, higher land compensation and causing civil complaint Excessive slope theft	By minimizing occupying area, damaged area around the land can be minimized High construction costs Poor construction on the strata above soft rock stratum Hard to build an access road for construction

Construction sequence

• Original around status
• Upper area excavation
• Crown arch installation
• Back filling and restoration
• Upper half excavation
• Upper half shocrete depositing and rock bolt installation
• Lower half excavation
• Lower half shocrete depositing and rock bolt installation
• Lining depositing

Construction cases