Numerical Analisis Numerik Pengaruh Diameter dan Kedalaman Cavity Tunggal Bentuk Lingkaran Dalam Lapisan Batu Kapur (Limestone) Terhadap Daya Dukung Fondasi Dangkal Di Atasnya
DOI:
https://doi.org/10.5614/jts.2025.32.1.7Keywords:
Cavity, limestone, shallow foundation bearing capacity, finite element method, Hoek-BrownAbstract
Abstrak
Penelitian ini menganalisis pengaruh diameter dan kedalaman cavity tunggal berbentuk lingkaran terhadap daya dukung fondasi dangkal pada lapisan batuan kapur (limestone) menggunakan metode elemen hingga (Finite Element Method). Parameter utama yang dievaluasi adalah daya dukung relatif (R) berdasarkan variasi diameter cavity (D) dan kedalaman cavity (H) yang relatif terhadap lebar fondasi (B). Karakteristik massa batuan dimodelkan menggunakan kriteria keruntuhan Hoek-Brown. Hasil analisis menunjukkan bahwa dalam kondisi batuan lemah, mekanisme keruntuhan utama adalah punching failure, di mana fondasi menembus lapisan atas batuan yang tidak mampu menahan beban. Cavity dengan diameter besar (D>B) pada kedalaman dangkal (H<B) diidentifikasi sebagai kondisi risiko tinggi, dengan pengurangan daya dukung 70-90% dibandingkan kondisi tanpa cavity. Kondisi ini membutuhkan prioritas penanganan pertama. Penelitian ini juga mengidentifikasi hubungan eksponensial yang mempermudah interpretasi data tanpa melibatkan variabel lebar fondasi (B), sehingga lebih praktis untuk aplikasi teknis. Dalam studi kasus, tiga kriteria desain diajukan: menghindari cavity risiko tinggi, memperkuat cavity, dan menggunakan desain fondasi adaptif. Temuan ini memberikan kontribusi penting dalam memahami pengaruh cavity pada fondasi dangkal di kawasan karst dan menyediakan panduan teknis yang praktis.
Kata Kunci: Cavity, batuan kapur, daya dukung fondasi dangkal, finite element method, Hoek-Brown.
Abstract
This study analyzes the effects of circular single cavity diameter and depth on the bearing capacity of shallow foundations in limestone layers using the Finite Element Method. Key parameters include relative bearing capacity (R) based on cavity diameter (D) and depth (H) relative to foundation width (B). The rock mass was modeled using the Hoek-Brown failure criterion. The results show that in weak rock conditions, the dominant failure mechanism is punching failure, where the foundation penetrates the weak upper rock layer. Cavities with large diameters (D>B) at shallow depths (H<B) are identified as high-risk conditions, reducing bearing capacity by 70-90% compared to conditions without cavities. These conditions require priority handling. The study identifies an exponential relationship simplifying data interpretation without involving foundation width (B), making it more practical for technical applications. In the case study, three design criteria are proposed: avoiding high-risk cavities, reinforcing cavities, and adopting adaptive foundation designs. These findings contribute significantly to understanding cavity effects on shallow foundations and provide practical guidelines for karst region structures.
Keywords: Cavity, limestone, shallow foundation bearing capacity, finite element method, Hoek-Brown.
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