Stability Analysis of the Nanjung Water Diversion Twin Tunnels based on Convergence Measurement

Simon Heru Prassetyo, Ganda Marihot Simangunsong, Ridho Kresna Wattimena, Made Astawa Rai, Irwandy Arif, Nuhindro Priagung Widodo, Dhika Noor Pradhana, Dimas Agung Saputra


This paper focuses on the stability analysis of the Nanjung Water Diversion Twin Tunnels using convergence measurement. The Nanjung Tunnel is horseshoe-shaped in cross-section, 10.2 m x 9.2 m in dimension, and 230 m in length. The location of the tunnel is in Curug Jompong, Margaasih Subdistrict, Bandung. Convergence monitoring was done for 144 days between February 18 and July 11, 2019. The results of the convergence measurement were recorded and plotted into the curves of convergence vs. day and convergence vs. distance from tunnel face. From these plots, the continuity of the convergence and the convergence rate in the tunnel roof and wall were then analyzed. The convergence rates from each tunnel were also compared to empirical values to determine the level of tunnel stability. In general, the trend of convergence rate shows that the Nanjung Tunnel is stable without any indication of instability. Although there was a spike in the convergence rate at several STA in the measured span, that spike was not replicated by the convergence rate in the other measured spans and it was not continuous. The stability of the Nanjung Tunnel is also confirmed from the critical strain analysis, in which most of the STA measured have strain magnitudes located below the critical strain line and are less than 1%.


Tunnel stability, Twin tunnels, Water diversion tunnel, Nanjung Tunnel, Convergence.

Full Text:



Cording, E.J., 1974. Measurement of displacement in tunnels, in: The Second International Congress of Engineering Geology , Sao Paulo, Brazil, August 18-24, 1974. International Association for Engineering Geology and the Environment, Sao Paulo.

Fakultas Teknik Pertambangan dan Perminyakan (FTTM), 2017. Review design of primary support of Notog tunnel BH 1440, Patikraja Sub-district–Banyumas Regency, Central Java (in Indonesian). Institut Teknologi Bandung, Bandung.

Hoek, E., Marinos, P., 2000. Predicting tunnel squeezing problems in weak heterogeneous rock masses. Part 1: Estimating rock mass strength (November, 2000) and Part 2: Estimating tunnelsqueezing problems (December, 2000). Tunnels Tunn. Int. Part 1: 45-51, Part II: 34-46.

Sakurai, S., 1983. Displacement measurements associated with the design of underground openings, in: Proceedings of the International Symposium of Field Measurements in Geomechanics, Zurich, Switzerland. pp. 1163–1178.

Zhenxiang, X., 1984. A tunnel design method using field measurement data, in: Design and Performance of Underground Excavations: ISRM Symposium - Cambridge, U.K., 3–6 September 1984. British Geotechnical Society, London, pp. 221–229.

Abstract views : 586 | views : 1049


  • There are currently no refbacks.

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.