Uji Model Konstitutif Generalized Hoek-Brown Dalam Analisis Stabilitas Lereng Guling (Toppling Failure) Menggunakan Finite Element Method (Fem), Studi Kasus Lereng Batuan = Generalized Hoek-Brown Constitutive Model Test In Toppling Failure Analysis Using Finite Element Method (Fem), Case Study Of Rock Slope