Pengaruh Pelapukan Lapisan Batuan Terhadap Stabilitas Lereng

Adolf Situmorang; Kusrin Kusrin; Ngudi Hari Christa; Yesina Intan Pratiwi; Galih Widyarini; Kukuh Wisnuaji Widiatmoko

doi:10.29103/tj.v12i2.707

Pengaruh Pelapukan Lapisan Batuan Terhadap Stabilitas Lereng

Adolf Situmorang, Kusrin Kusrin, Ngudi Hari Christa, Yesina Intan Pratiwi, Galih Widyarini, Kukuh Wisnuaji Widiatmoko

Abstract

Abstrak

Longsor merupakan suatu proses perpindahan massa batuan atau tanah akibat pengaruh gravitasi sebagai respon terhadap aktivitas alam yang menyebabkan kerusakan morfologi permukaan lereng, dan longsor yang terjadi di Wonogiri kemungkinan karena pelapukan lapisan batuan akibat curah hujan yang sering terjadi di aera tersebut. Penelitian ini dilakukan dengan tahapan pengambilan sampel batuan, pengukuran dan pengumpulan data sekunder. Klasifikasi batuan menggunakan parameter RQD, RMR dan Q-system untuk mengetahui karakteristik batuan. Hasil dari klasifikasi tersebut menunjukkan bahwa lapisan batuan di lokasi longsor masuk dalam kategori sedang hingga sangat rentan mengalami pelapukan. Dengan mempertimbangkan siklus curah hujan dan jumlah hujan dalam hari yang dihitung dalam satu tahun diketahui ada pengurangan kekuatan batuan berdasarkan penelitian terdahulu. Hasil analisa metode element hingga menunjukkan terjadi pengurangan kekuatan batuan berdasarkan parameter geser yang berakibat pada stablititas lereng batuan tersebut, dan pada tahun ke-10 diindikasikan nilai Safety Factor (SF) <1,3.

Kata kunci: Kuat geser, siklus basah-kering, batuan

Abstract

Landslide is a process of mass transfer of rock or soil due to the influence of gravity in response to natural activities that cause damage to the surface morphology of the slopes, and the landslide that occurred in Wonogiri was probably due to weathering of rock layers due to frequent rainfall in the area. This research was conducted with the stages of taking rock samples, measuring and collecting secondary data. Rock classification uses RQD, RMR and Q-system parameters to determine rock characteristics. The results of the classification indicate that the rock layers at the landslide location are in the moderate to very vulnerable category to weathering. By considering the rainfall cycle and the amount of rain in days calculated in one year, it is known that there is a reduction in rock strength based on previous research. The results of the finite element method analysis showed that there was a reduction in rock strength based on shear parameters which resulted in the stability of the rock slopes, and 10th year indicated the value of Safety Factor (SF) <1.3.

Keywords: Landslide, wet-dry cycle, rock

Keywords

Landslide, wet-dry cycle, rock

Full Text:

PDF

References

Azimian, A, 2016. A new method for improving the RQD determination of rock core in borehole. Rock Mechanics and Rock Engineering, 49(4), 1559–1566. https://doi.org/10.1007/s00603-015-0789-8

Badan Standarisasi Nasional, 2017. Sni 8460-2017. Persyaratan Perancangan Geoteknik, 8460, 2017.

Barton, N, 2002. Some new Q-value correlations to assist in site characterisation and tunnel design. International Journal of Rock Mechanics and Mining Sciences, 39(2), 185–216. https://doi.org/10.1016/S1365-1609(02)00011-4

Barton, N., Lien, R., & Lunde, J, 1974. Engineering classification of rock masses for the design of tunnel support. Rock Mechanics Felsmechanik Mecanique Des Roches, 6(4), 189–236. https://doi.org/10.1007/BF01239496

Bieniawski, 1989. Engineering Rock Mass Clasifications.

El-Haddad, B. A., Youssef, A. M., El-Shater, A. H., & El-Khashab, M. H, 2021. Landslide mechanisms along carbonate rock cliffs and their impact on sustainable development: a case study, Egypt. Arabian Journal of Geosciences, 14(7), 1–14. https://doi.org/10.1007/s12517-021-06688-1

Huang, S., Wang, J., Qiu, Z., & Kang, K, 2018. Effects of cyclic wetting-drying conditions on elastic modulus and compressive strength of sandstone and mudstone. Processes, 6 (12). https://doi.org/10.3390/pr6120234

Komadja, G. C., Pradhan, S. P., Roul, A. R., Adebayo, B., Habinshuti, J. B., Glodji, L. A., & Onwualu, A. P, 2020. Assessment of stability of a Himalayan road cut slope with varying degrees of weathering: A finite-element-model-based approach. Heliyon, 6 (11). https://doi.org/10.1016/j.heliyon.2020.e05297

Li, Z., Liu, S., Ren, W., Fang, J., Zhu, Q., & Dun, Z, 2020. Multiscale Laboratory Study and Numerical Analysis of Water-Weakening Effect on Shale. Advances in Materials Science and Engineering, 2020. https://doi.org/10.1155/2020/5263431

Miščević, P., & Vlastelica, G, 2014. Impact of weathering on slope stability in soft rock mass. Journal of Rock Mechanics and Geotechnical Engineering, 6(3), 240–250. https://doi.org/10.1016/j.jrmge.2014.03.006

Naryanto, H. S., Soewandita, H., Ganesha, D., Prawiradisastra, F., & Kristijono, A, 2019. Analisis Penyebab Kejadian dan Evaluasi Bencana Tanah Longsor di Desa Banaran, Kecamatan Pulung, Kabupaten Ponorogo, Provinsi Jawa Timur Tanggal 1 April 2017. Jurnal Ilmu Lingkungan, 17(2), 272. https://doi.org/10.14710/jil.17.2.272-282

Shahabi, H., & Hashim, M, 2015. Landslide susceptibility mapping using GIS-based statistical models and Remote sensing data in tropical environment. Scientific Reports, 5, 1–15. https://doi.org/10.1038/srep09899

Situmorang, A., & Muldiyanto, A, 2021. The Effectiveness of Wire Mesh to Protect Landslide Rockfall Type. xx(xx), 45–50.

Yasuda, S, 2012. Reduction of static and dynamic shear strength due to the weathering of mudstones. 15th World Conference on Earthquake Engineering, Lisbon Portugal, 4–11.

Zhang, Q., Huang, X., Zhu, H., & Li, J, 2019. Quantitative assessments of the correlations between rock mass rating (RMR) and geological strength index (GSI). Tunnelling and Underground Space Technology, 83(April 2018), 73–81. https://doi.org/10.1016/j.tust.2018.09.015

Zhao, Y., Ren, S., Jiang, D., Liu, R., Wu, J., & Jiang, X, 2018. Influence of wetting-drying cycles on the pore structure and mechanical properties of mudstone from Simian Mountain. Construction and Building Materials, 191, 923–931. https://doi.org/10.1016/j.conbuildmat.2018.10.069

Zhao, Z., Yang, J., Zhang, D., & Peng, H, 2017. Effects of Wetting and Cyclic Wetting–Drying on Tensile Strength of Sandstone with a Low Clay Mineral Content. Rock Mechanics and Rock Engineering, 50(2), 485–491. https://doi.org/10.1007/s00603-016-1087-9

Zheng, J., Yang, X., Lü, Q., Zhao, Y., Deng, J., & Ding, Z, 2018. A new perspective for the directivity of Rock Quality Designation (RQD) and an anisotropy index of jointing degree for rock masses. Engineering Geology, 240(April), 81–94. https://doi.org/10.1016/j.enggeo.2018.04.013.

DOI: https://doi.org/10.29103/tj.v12i2.707