PARAMETRIC STUDY OF TUNNEL ANALYSIS IN CLAYSHALE ON SHORT TERM AND LONG TERM CONDITION WITH FINITE ELEMENT PROGRAM

• Main Author: Setiya Raharja, Danang
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/51465
• Institution: Institut Teknologi Bandung

The development of transportation facilities has boosted the speed of access, both in the form of toll roads and railways. This access speed demands a more gentle and straight geometric shape of the road and railroad in horizontal and vertical alignments. So that in hilly areas, a tunnel structure that penetrates the hill is required. Tunnel construction in the West Java area is faced with a new challenge, namely the clayshale formation. This study aims to determine the characteristics and classification of clayshale soil in West Java and its implications for tunnel stability in short-term and long-term conditions with the finite element program (Plaxis). Secondary data from the project in West Java which contained clayshale, in the form of field and laboratory investigation data, were collected and analyzed. It was found that clayshale was spread in 4 rock formations from the youngest to the oldest, namely Cihoe Formation (Tpc), Subang Formation (Tms), Cantayan Formation (Mtts / Mttc), and Jatiluhur Formation (Tmj). Each formation has quite different mechanical and engineering properties. The proposed identification of clayshale’s weathering levels in the Cihoe Formation are N-SPT <40 Fully Weathered, N-SPT 40-60 Highly Weathered to Moderately Weathered, and N-SPT >60 Slighly Weathered to Unweathered. The proposed identification of clayshale’s weathering levels in the Subang Formation is N-SPT <60 Fully Weathered and NSPT >60 Highly Weathered to Unweathered. Plaxis analysis with MC model resulted smaller deformation in tunnel crown, smaller surface deformation, greater effective stress, and greater excess pore water pressure than HS model. Long-term stability is lower than short-term but deformation during construction is the most dominant because the increase in deformation in long-term conditions is relatively small.