ANALYSIS SLOPE STABILITY
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II. Nilai- Nilai Parameter Tanah
Parameter Humus Berpasir Lempung
Material Model Mohr-coulomb Mohr-coulomb
Type of Material Undrained drained
Dry soil weight γd 16 16
III. Analisis Pembebanan
Tower
Beban Tower = 50 kN
IV. Analisis Kelongsoran dengan Aplikasi Plaxis v.8.2 A. Plaxis Input
IV.1. Tahap Gravity Loading
Tahap awal dari analysis digunakan untuk menghitung tegangan-tegangan awal akibat berat sendiri massa tanah dan tegangan-tegangan horosontal.
Fase 1: Gravity Loading
Calculation type:plascic
Start from phase: 0 – initial phase Parameter:
- Additional step = 100 - Ignore undrained behaviour - Delete intermediate steps - Loading input: total multipliers Multipliers:
Σ Mweight_= 1 (maksudnya tegangan tanah terjadi dari berat sendiri tanah
sendiri sehingga factor pengali beratnya = 1).
IV.2. Tahap Safety Factor akibat Gravity Loading
Untuk mencari factor aman sebelum ada beban pondasi.
Fase 2: SF gravity loading
Calculation type:Phi-c reduction
Start from phase: 1 – Gravity Loading Parameter:
- Additional step = 100
- Loading input: increment multipliers Multipliers:
Σ MSF_= 0.1
IV.3. Tahap Beban Pondasi
Fase 3: beban pondasi
Calculation type:Plastic
Start from phase: 2 – Safety Factor akibat Gravity Loading Parameter:
- Additional step = 100
- Loading input: staged construction - Reset displacement to Zero - Delete intermediate steps
IV.4. Tahap Beban Luar
Fase 4: beban luar
Calculation type:Plastic
Start from phase: 3 – beban pondasi Parameter:
- Additional step = 100 - Delete intermediate steps - Loading input: total multipliers
IV.5. Tahap SF Pondasi dan Beban Tower
Fase 5: SF Pondasi dan Beban Tower
Calculation type:Phi-c reduction
Start from phase: 4 – beban luar Parameter:
- Additional step = 100
- Loading input: increment multipliers Multipliers:
B. Plaxis Input
1. Tahap Gravity Loading
Pada tahap ini menunjukkan hasil bahwa dengan berat sendiri tanah, pada lereng mengalami pergerakan sebesar 165.07E10-3 m.
Gambar 2. Lereng terdeformasi akibat Gravity Loading
2. Tahap Vertical Loading
Pada tahap ini tanah menerima beban yang dimodelkan sebagai beban merata (tractions). Tanah mengalami deformasi yaitu sebesar 285.57E10-3m.
Gambar 4. Lereng terdeformasi akibat Vertical Loading
PLAXIS CURVE V.8
Angka keamanan akibat Beban Pondasi dan Tower:
Dari Kurva diketahui bahwa SF akibat gravity loading dan beban Pondasi dan tower adalah1.352. Angka ini lebih kecil dibandingkan dengan SF minimal untuk keruntuhan yaitu 1.5
Sehingga disimpulkan bahwa lereng tidak aman jika gravity dan Beban pondasi dan tower bekerja maksimal.
V. Kesimpulan
displacement vector (¦u¦)
ΣMstage
the ΣMstage parameter is associated with the Staged construction option in PLAXIS (see Staged construction). This total multiplier gives the proportion of a construction stage that has been completed. Without input from the user, the value of ΣMstage is always zero at the start of a staged construction analysis and at the end it will generally be 1.0. It is possible to specify a lower ultimate level of ΣMstage using the Advanced option of the Parameters tab sheet. However, care should be taken with this option. In calculations where the loading input is not specified as Staged construction, the value of ΣMstage remains zero.
ΣMarea
The ΣMarea parameter is also associated with the Staged construction option. This parameter gives the proportion of the total volume of soil clusters in the geometry model that is currently active. If all soil clusters are active then ΣMarea has a value of 1.0.
Stiffness
As a structure is loaded and plasticity develops then the overall stiffness of the structure will decrease. The Stiffness parameter gives an indication of the loss of stiffness that occurs due to material plasticity. The parameter is a single number that is 1.0 when the structure is fully elastic and reduces in magnitude as plasticity develops. At failure the value is approximately zero. It is possible for this parameter to have negative values if softening occurs.
Pmax
The Pmax parameter is associated with undrained material behaviour and represents the maximum absolute excess pore pressure in the mesh, expressed in the unit of stress. During undrained loading in a plastic calculation Pmax generally increases, whereas Pmax generally decreases during a consolidation analysis.
Stresses
σ'xx effective horizontal stress (x-direction) σ 'yy effective vertical stress (y-direction)
σ 'zz effective stress in the out-of-plane direction (z-direction) σ xy shear stress
σ '1 in absolute sense the largest effective principal stress σ '2 the intermediate effective principal stress
σ '3 in absolute sense the smallest effective principal stress p' isotropic effective stress (mean effective stress)
q deviatoric stress (equivalent shear stress) p excess excess pore pressure
See the Scientific Manual for a definition of the stress and strain components. The phrase 'in absolute sense' in the description of the principal components is added because, in general, the normal stress and strain components are negative
Memulai Plaxis 8.x
Program > Plaxis 8.x > 1. Plaxis Input
General Setting
Isi Title,
Contoh: Slope Stability
Pemodelan
Pilih Geometry line, (tool yang diberi kotak)
Jika lereng masih dalam kondisi existing.
Setelah pemodelan, Pilih Loads > Standard Fixities
Maka akan seperti gambar dibawah ini:
Isi Data Tanah sesuai dengan data hasil pengujian tanah. Pilih Contoh tanah
yang mendekati keadaan sebenarnya Pindahkan Kekotak sebelah kiri
Setelah selesai Klik sambil ditahan lalu pindahkan ke gambar tempat tanah tersebut,
Klik sambil ditahan
Langkah selanjutnya adalah Pilih Generete Mest seperti gambar dibawah ini:
Hasilnya akan seperti gambar dibawah ini:
Pilih Update
Pilih Initial condition
Tahap Gravity Loading
Tahap awal dari analysis digunakan untuk menghitung tegangan-tegangan awal akibat berat sendiri massa tanah dan tegangan-tegangan horosontal.
Fase 1: Gravity Loading
Calculation type:plascic
Start from phase: 0 – initial phase Parameter:
- Additional step = 100 - Ignore undrained behaviour - Delete intermediate steps - Loading input: total multipliers Multipliers:
Σ Mweight_= 1 (maksudnya tegangan tanah terjadi dari berat sendiri tanah
Tahap Safety Factor akibat Gravity Loading
Untuk mencari factor aman sebelum ada beban pondasi.
Fase 2: SF gravity loading
Calculation type:Phi-c reduction
Start from phase: 1 – Gravity Loading Parameter:
- Additional step = 100
- Loading input: increment multipliers Multipliers:
Pilih Project yang akan dibuka, *.DTA > Open
Untuk melihat model tampilannya.
