Pengembangan Model untuk Memprediksi Ballast Settlement pada Kondisi Beban Gandar dan Kecepatan Kereta Api yang Berbeda
M.D. Prawira1*, S.H.T. Utomo1, T. Rahman1
1Departemen Teknik Sipil dan Lingkungan, Universitas Gadjah Mada, Yogyakarta, INDONESIA
*Corresponding author: muhammaddanuprawira@mail.ugm.ac.id
INTISARI
Jalur kereta api dapat mengalami deformasi plastis (atau settlement) akibat dari beban dinamis kereta api. Settlement ini dapat berdampak buruk terhadap geometri jalur bila melebihi ambang batas yang dipersyaratkan. Ballast settlement dianggap memberikan berkontribusi paling besar dibanding lapisan struktur lainnya terhadap keseluruhan settlement. Besaran beban gandar dan kecepatan kereta api memiliki peranan penting terhadap ballast settlement. Untuk mengetahui perubahan geometri jalur kereta api, diperlukan pemahaman terhadap settlement yang muncul akibat faktor-faktor tersebut, salah satunya memprediksi tingkat settlement yang dapat terjadi. Oleh karena itu, makalah ini bertujuan untuk mengembangkan model empiris untuk memprediksi ballast settlement pada beban gandar dan kecepatan kereta api yang berbeda. Pengembangan model didasarkan pada data pengujian laboratorium yang telah dilakukan terdahulu. Formulasi model dilakukan dengan menganalisis best-fit curve dan best-fit equation pola pertumbuhan settlement ballast. Rumus logaritmik dipilih sebagai best-fit equation karena mampu memberikan hasil pengukuran yang paling mendekati dengan pola ballast settlement pada hasil pengujian laboratorium. Berdasarkan hasil validasi model, rumus logaritmik tersebut termasuk dalam kategori “Baik” untuk memprediksi settlement ballast berdasarkan nilai Mean Absolute Percentage Error (MAPE).
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