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Purpose – The purpose of this paper is to establish a peridynamic method in predicting viscoelastic creep behaviour with recovery stage and to find the suitable numerical parameters of peridynamic method. Design/methodology/approach – A rheological viscoelastic creep constitutive equation including recovery and an elastic peridynamic equation (with integral basis) are examined and used. The elasticity equation within the peridynamic equation is replaced by the viscoelastic equation. A new peridynamic method with two time parameters, i.e. numerical time and viscoelastic real time is designed. The two parameters of peridynamic method, horizon radius and number of nodes per unit volume are studied to get their optimal values. In validating this peridynamic method, comparisons are made between numerical and analytical result and between numerical and experimental data. Findings – The new peridynamic method for viscoelastic creep behaviour is approved by the good matching in numerical-analytical data comparison with difference of < 0.1 per cent and in numerical-experimental data comparison with difference of 4-6 per cent. It can be used for further creep test which may include non-linear viscoelastic behaviour and creep rupture. From this paper, the variation of constants in Burger’s viscoelastic model is also studied and groups of constants values that can simulate solid, fluid and solid-fluid viscoelastic behaviours were obtained. In addition, the numerical peridynamic parameters were also manipulated and examined to achieve the optimal values of the parameters. Research limitations/implications – The peridynamic model of viscoelastic creep behaviour preferably should have only one time parameter. This can only be done by solving the unstable fluctuation of dynamic results, which is not discussed in this paper. Another limitation is the tertiary region and creep rupture are not included in this paper. Practical implications – The viscoelastic peridynamic model in this paper can serve as an alternative for conventional numerical simulations in viscoelastic area. This model also is the initial step of developing peridynamic model of viscoelastic creep rupture properties (crack initiation, crack propagation, crack branching, etc.), where this future model has high potential in predicting failure behaviours of any components, tools or structures, and hence increase safety and reduce loss. Originality/value – The application of viscoelastic creep constitutive model on peridynamic formulation, effect of peridynamic parameters manipulation on numerical result, and optimization of constants of viscoelastic model in simulating three types of viscoelastic creep behaviours.

AbstrakSalah satu dampak dari suatu risiko longsoran lereng tambang terbuka adalah jatuhnya material longsor ke dalam tambang yang sedang melakukan operasi tambang yang berakibat dapat menimbulkan terjadinya fatalitas dan/atau cidera bagi pekerja, serta kerusakan properti perusahaan. Oleh sebab itu analisis kestabilan suatu lereng selain digunakan untuk menentukan nilai faktor keamanan (FK) dan probabilitas kelongsoran (PK) lereng, juga dapat memprediksi besaran volume longsoran bila terjadi kegagalan dalam disain lereng. Penelitian ini menggunakan metode kesetimbangan batas (limit equilibrium method) 3 dimensi dalam penentuan volume longsoran lereng dengan lokasi pada tambang terbuka batugamping di Rembang, Jawa Tengah. Ke depan diharapkan pendekatan ini dapat dimanfaatkan para praktisi untuk perencanaan mitigasi kelongsoran lereng. Kata Kunci : Tambang terbuka, stabilitas lereng, metode kesetimbangan batas 3 dimensi, dampak longsoran AbstractOne of the consequences from a risk of open pit failure is the fallen of the failure material in a mine that is doing the mine operation that can cause fatality and/or injury to workers, and damage to company properties. Therefore, the slope stability analysis is not only used to determine the safety factor (SF) and failure probability (FP), but it can also predict the amount of the volume of failure if there is any fault in the slope design. This research used 3D limit equilibrium method in determining the volume of potential failure of an open pit limestone mine in Rembang, Central Java. In the future, it is hoped that this approach can be utilized by practitioners for mitigation of slope failure planning. Keywords : Open pit, slope stability, 3D limit equilibrium method, consequence of failure PENDAHULUANResiko longsoran dapat dikuantifikasi dengan mengalikan probabilitas kelongsoran dan konsekuensi. Manajemen resiko perlu dilakukan untuk meyakinkan potensi

PT X had an accident  of slope failure that caused fatalities and injuries experienced by labor mining, and also some heavy mining equipments  buried  by  materials  that causing companies got financial loss. therefore important to analyze the slope stability of surface mining operation, and predicting total volume of slope failure to anticipate the impact of fatalities/ injuries and financial risks. This research  aim is  to analyze  slope stability before failure conditions, predicting volume of slope failure, and determine position of critical zone using limit equilibrium “Simpilfied Bishop” method 3-dimensional, then doing validation with calculation of actual volume by comparing results of topography maps before and after failure using the cut and fill method. From the result of research, the slope on unstability conditions, actual and predicted volume of  slope failure is  8,629 m3 and 10,559 m3, so percent of calculation error is 18.3% .