PERGERAKAN DINDING TEROWONGAN PADA VARIASI GEOMETRI TEROWONGAN YANG TIDAK DISANGGA DENGAN ANALISA AXISYMMETRIC SKALA LABORATORIUM

Bayurohman Pangacella Putra

Bayurohman Pangacella Putra Institut Teknologi Nasional Yogyakarta

Abstract

Inward tunnel deformation can cause safety risk, such as rock squeezing and tunnel wall and roof failure. Analysis of influence of tunnel diameter and length ratio is needed to be carried out. Analysis is carried out by using Axisymmetric assuming the tunnel profile is circular and excavated in a homogen and isotrop rock mass to determine the tunnel inward total displacement. Three tunnels with different diameters, 5 m, 8 m, and 10m, are modeled separately. Total displacement is evaluated on the same D/L among these models, looking for a D/L ratio that gives no change of displacement compared to previous excavation stage. The result shows that D/L = 1/3 on the three models gives neglgible inward tunnel displacement, with 5% tolerance of approximation error. About 50% value from the maximal displacement are reached at D/L = 1. Percentage value from the maximal displacement (y) can be related to D/L by equation y = 1,49e-1,08D/L.

References

[1] Hoek, E. & Marinos, P. Predicting tunnel squeezing problems in weak heterogenous rock. Tunnels and Tunneling International. 2000.
[2] Putra, B.P., et al. 2018. Squeezing pada Massa Batuan Sekitar Terowongan di Daerah Tambang Cikoneng, Banten. Curvatek. 2017
[3] Widodo, N.P., Evaluation of Rock Mass Condition at Cikoneng Bypass Ch 36.5 – 39 m. PT LAPI ITB. 2008
[4] Perman, F., Sjoberg, J. Numerical Analysis of Shotcrete Reinforcement. 2007
[5] Hoek, E., Tunnel Support in Weak Rock. Symposium of Sedimentary Rock Engineering. Taipei, Taiwan. 1998
[6] Putra, B.P. Plastic Zone Prediction Using Finite Element Method on Cikoneng Decline Tunnel at PT. Cibsliung Sumberdaya. Asian Rock Mechanics Symposium. Bali, Indonesia. 2016.
[7] Hoek, E., Kaiser, P.K., Bawden, W.F. Support of Underground Excavation in hard Rock.
[8] Brady, B.H.G dan Brown, E.T., Rock Mechanics for Underground Minings. George Allen & Unwin, London, halaman 151-164, 464, (1985).
[9] Putra, B.P., Prediksi Zona Plastik Menggunakan Metode Finite Element pada Terowongan Decline Cikoneng PT. Cibaliung Sumberdaya. Tesis Magister Program Studi Rekayasa Pertambangan Bidang Khusus Geomekanika ITB. 2015
[10] Hakim, R. N., Studi Kestabilan Stope Menggunakan Data Monitoring dengan Total Station. Tesis Magister Program Studi Rekayasa Pertambangan Bidang Khusus Geomekanika ITB. 2014
[11] Winarno, P.P.A., Studi Monitoring Deformasi Lubang Bukaan Menggunakan Total Station X-Cut 4 Access dan Decline Cikoneng Tambang Emas PT Cinaliung Sumberdaya. Tugas Akhir Program Studi Teknik Pertambangan ITB. 2015
[12] Sipayung, H. Prediction of Tectonic Stress Based on Fault Slip at PT Cibaliug Sumberdaya. International Symposium of Earth Science and Technology . 2014