ANALYSIS SLOPE STABILITY Site ID : Site Name : I. Data Boring LOG By: dedy trianda Hal. 1
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 Wet soil weight γs 18 20 Permeability in hor. direction Kx 1 1 Permeability in ver. direction Ky 1 1 Young s modulus E 9000 15000 Poisson s ratio v 0.3 0.3 Cohesion (constant) C 1 10 Friction Angel Φ 30 30 Dilatancy angel ψ 0 0 III. Analisis Pembebanan Tower Beban Tower = 50 kn IV. Analisis Kelongsoran dengan Aplikasi Plaxis v.8.2 A. Plaxis Input Gambar 1. Geometri Lereng By: dedy trianda Hal. 2
IV.1. Tahap Gravity Loading Tahap awal dari analysis digunakan untuk menghitung tegangantegangan awal akibat berat sendiri massa tanah dan 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 M weight_ = 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. IV.4. 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 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 Multipliers: Σ M load A_ = 50 kn By: dedy trianda Hal. 3
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: Σ MSF _ = 0.1 By: dedy trianda Hal. 4
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 Gambar 3. arah gerakan tanah dan penurunan akibat gravity Loading By: dedy trianda Hal. 5
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 Gambar 5. arah gerakan tanah dan penurunan akibat Vertical Loading By: dedy trianda Hal. 6
Gambar 6. arah gerakan tanah dan penurunan akibat Vertical Loading (shading model) By: dedy trianda Hal. 7
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 Lereng tidak aman dan dibutuhkan retaining wall untuk stabilitas lereng. By: dedy trianda Hal. 8
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 σ 'yy σ 'zz σ xy σ '1 σ '2 σ '3 p' q p excess effective horizontal stress (x-direction) effective vertical stress (y-direction) effective stress in the out-of-plane direction (z-direction) shear stress in absolute sense the largest effective principal stress the intermediate effective principal stress in absolute sense the smallest effective principal stress isotropic effective stress (mean effective stress) deviatoric stress (equivalent shear stress) 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 (compression is negative). Note that the deviatoric stress and strain components are always positive. Stress components are expressed in the units of stress; strains are dimensionless. By: dedy trianda Hal. 9
Memulai Plaxis 8.x Program > Plaxis 8.x > 1. Plaxis Input Pilih New Project > OK By: dedy trianda Hal. 10
General Setting Isi Title, Contoh: Slope Stability Setting Units, Geometry Dimensions atau ukuran lembar kerja dan Grid, Pilih OK By: dedy trianda Hal. 11
Pemodelan Pilih Geometry line, (tool yang diberi kotak) Gambarkan Geometrynya sesuai dengan kondisi lapangan. By: dedy trianda Hal. 12
Jika lereng masih dalam kondisi existing. Setelah pemodelan, Pilih Loads > Standard Fixities Maka akan seperti gambar dibawah ini: Kemudian Pilih Material Sets By: dedy trianda Hal. 13
Pilih Contoh tanah yang mendekati keadaan sebenarnya Pindahkan Kekotak sebelah kiri Pilih Edit Isi Data Tanah sesuai dengan data hasil pengujian tanah. By: dedy trianda Hal. 14
By: dedy trianda Hal. 15
Setelah selesai Klik sambil ditahan lalu pindahkan ke gambar tempat tanah tersebut, Klik sambil ditahan Lepas disini By: dedy trianda Hal. 16
Langkah selanjutnya adalah Pilih Generete Mest seperti gambar dibawah ini: Hasilnya akan seperti gambar dibawah ini: Pilih Update Pilih Initial condition Isi berat jenis air > OK By: dedy trianda Hal. 17
Langkah selanjutnya adalah: Pilih Calculate By: dedy trianda Hal. 18
Tahap Gravity Loading Tahap awal dari analysis digunakan untuk menghitung tegangantegangan awal akibat berat sendiri massa tanah dan 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 M weight_ = 1 (maksudnya tegangan tanah terjadi dari berat sendiri tanah sendiri sehingga factor pengali beratnya = 1). By: dedy trianda Hal. 19
By: dedy trianda Hal. 20
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 By: dedy trianda Hal. 21
By: dedy trianda Hal. 22
Pilih Project yang akan dibuka, *.DTA > Open Hasilnya adalah sebagai berikut: By: dedy trianda Hal. 23
Untuk melihat model tampilannya. Pilih Deformations > Total displacements Atau yang lainnya. By: dedy trianda Hal. 24