Perilaku tegangan deformasi tanah jenuh sebagian akibat beban statis

ARIF, Didit Nur, Dr.Ir. Ahmad Rifa'i, M.T

2005 | Tesis | S2 Teknik Sipil

Perubahan musim di Indonesia memberikan fluktuasi kadar air tanah akibat hujan, evaporasi dan evapotransiprasi. Butiran-butiran tanah rentan terhadap perubahan kadar air terutama kuat dukungnya yang terkondisi jenuh (saturated) dan jenuh sebagian (unsaturated). Kuat dukung timbunan yang dipengaruhi kadar air secara langsung mempengaruhi perilaku tegangan dan regangannya. Fenomena ini menarik untuk diteliti sejauh mana pengaruh kadar air terhadap kuat dukung tanah dengan mengidealisasikan pada uji model dua dimensi di laboratorium yang kemudian dianalisis dengan simulasi numeris. Penelitian ini meninjau perilaku tegangan deformasi tanah yang dipadatkan 90% γdmax pada bak uji dan sampel triaksial UU (unconsolidated undrained), kemudian setiap perubahan kadar air dikalibrasikan dengan matric suction yang mengacu ASTM D5298-03. Perilaku tegangan deformasi dan displacement tanah disimulasikan dengan program Plaxis dengan parameter input hasil triaksial UU. Hasil penelitian menunjukkan hasil bahwa tanah menurut Unified terklasifikasi lanau plastisitas rendah (ML) yang memiliki persamaan matric suction . Analisis kuat geser tanah jenuh sebagian dengan triaksial UU mendapatkan φ f (w ) = 107 e−0.6519w b = 4.71°; 5.14°; 5.85° dapat digunakan sebagai parameter prediksi kuat dukung tanah akibat perubahan kadar air. Perilaku matric suction mempengaruhi sifat mekanis tanah jenuh sebagian yaitu semakin meningkat matric suctionnya maka perilaku kuat geser, faktor kedalaman penyebaran tegangan, elastisitas tanah dan kuat dukung tanah akan meningkat signifikan. Program Plaxis dapat digunakan untuk menganalisis perilaku deformasi dan displacement tanah jenuh sebagian dengan analisis numeris di bak uji idealisasi plane strain dengan tipe material drained tanpa memasukan parameter muka air tanah.

The changing of climate in Indonesia gives fluctuation of water soil content in its result rain, evaporation and evapo-transpiration. Soil granulation is very sensitive to water soil content changing especially bearing capacity in saturated soil and unsaturated soil condition. The Bearing capacity of filled soil which is influenced by water content directly impact stress and strain behavior. This phenomenon is very interesting to be researched, how far water content influence the soil bearing capacity by using two dimension testing model in laboratory and to be analyzed by using numerical simulation. The objective of this research is to observe soil deformation with its density 90% γdmax in density box experiment and unconsolidated un-drained triaxial testing sample, and then the changes of soil water content in every test were calibrated as a change of matric suction refers to ASTM D5298-03. Behavior of deformation strength and displacement be analyzed by using numerical simulation with Plaxis program with input data result of the unconsolidated un-drained triaxial testing (UU). The experiment shows that the soil according Unified classification is silt low plasticity (ML) which has formula matric suction . Analysis shear stress of unsaturated soil with triaxial UU be found φ f (w ) = 107 e−0.6519w b = 4.71°; 5.14°; 5.85° be used prediction bearing capacity parameters consequence changes of soil water content. Behavior of matric suction influences mechanic of unsaturated soil, if matric suction increases, shear stress, elasticity, deep distributing stress factor and bearing capacity will be significant increased. Plaxis program can be used to analyze behaviour of deformation and displacement of unsaturated soil with numerical analysis on box experiment in idealization plane strain with type drained material without input water level parameters.

Kata Kunci : Tegangan Deformasi Tanah, Kadar Air, Kuat Geser Tanah, unsaturated soil, matric suction, deformation.