Abstract
This paper presents the results of geological engineering research conducted to determine the character of rock masses, recommendations of tunnel excavation method and support system based on standup time estimates in unsuported conditions. The investigation was conducted by observing rock mass quality based on the newest bore log sample test results in 2019 using Rock Mass Rating (RMR) and Geological Strength Index (GSI) rock mass classification. The results showed that area consist of lithology in the form of porphyryc lava basalt and pyroclastic volcanic breccia. Rock mass has a slightly weathering alteration rates. Intact rocks have Uniaxial Compressive Strength (UCS) values ranging from 100-250 Mpa to >250 Mpa and are a category of strong rocks. Rock mass has fair to good rock quality class III-II based on RMR values between 53-69, GSI values between 48-64. The roof span required is obtained from the tunnel planning roof span of 10 meter, with a stand-up time of 70 hours without support system and immediate collapse for 5 days. The recommended excavation methods are excavation by drill and blast on top heading and bench: 1,5-3 meter advance in top heading tunnel face, and then can be recommended support system using rock bolts (20 mm diameter, fullly bonded): systematic bolts 4 meter long, spaced 1,5-2 meter in crown and bench with wiremesh in crown then shotcrete: 50-100 mm in crown, and 30 mm in sides, without steel ribs support.
Highlights
IntroductionGeological investigation of subsurface engineering at the site of the diversion tunnel plan using the newest bore log test is carried out to know in detail the type of rock/soil, structure, the strength of rocks, permeability and thickness of the soil layer that will be used as a guideline to determine the design and geometry trace of the tunnel.adequate geological data is needed to support the right methods and stages to be able to reduce the risk of construction failure.The purpose of the classification of rock mass is to group the types of rock mass based on his behavior, as the basis for understanding the character of each class, provide quantitative data to determine excavations methods and tunnel’s support system.This research aims to observe and analyze bore log test result to determine the quality of rock mass using Rock Mass Rating (Bienawski,1989) and Geological Strength Index (Hoek&Brown, 2002) in the Pamukkulu’s Dam diversion tunnel.And determine the stand-up time of tunnel without support system to provide recommendations on excavation methods and tunnel support systems on tunnel’s rocks that are effectively based on quality profile of rock mass.Previous studies have been conducted to investigate the quality of rock mass with criepi’s method
This paper presents the results of geological engineering research conducted to determine the character of rock masses, recommendations of tunnel excavation method and support system based on stand- up time estimates in unsuported conditions
The results showed that area consist of lithology in the form of porphyryc lava basalt and pyroclastic volcanic breccia
Summary
Geological investigation of subsurface engineering at the site of the diversion tunnel plan using the newest bore log test is carried out to know in detail the type of rock/soil, structure, the strength of rocks, permeability and thickness of the soil layer that will be used as a guideline to determine the design and geometry trace of the tunnel.adequate geological data is needed to support the right methods and stages to be able to reduce the risk of construction failure.The purpose of the classification of rock mass is to group the types of rock mass based on his behavior, as the basis for understanding the character of each class, provide quantitative data to determine excavations methods and tunnel’s support system.This research aims to observe and analyze bore log test result to determine the quality of rock mass using Rock Mass Rating (Bienawski,1989) and Geological Strength Index (Hoek&Brown, 2002) in the Pamukkulu’s Dam diversion tunnel.And determine the stand-up time of tunnel without support system to provide recommendations on excavation methods and tunnel support systems on tunnel’s rocks that are effectively based on quality profile of rock mass.Previous studies have been conducted to investigate the quality of rock mass with criepi’s method. The purpose of the classification of rock mass is to group the types of rock mass based on his behavior, as the basis for understanding the character of each class, provide quantitative data to determine excavations methods and tunnel’s support system. This research aims to observe and analyze bore log test result to determine the quality of rock mass using Rock Mass Rating (Bienawski,1989) and Geological Strength Index (Hoek&Brown, 2002) in the Pamukkulu’s Dam diversion tunnel. Determine the stand-up time of tunnel without support system to provide recommendations on excavation methods and tunnel support systems on tunnel’s rocks that are effectively based on quality profile of rock mass. High uncertainty in that rock mass classification method requires more analysis of rock quality with other methods namely RMR and GSI, using the latest bore log test data investigation in 2019
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
