MEKANIKA TANAH 1

MEKANIKA TANAH 1

PERTEMUAN VIEffective Stress Theory

Oleh :Arwan Apriyono

PROGRAM STUDI TEKNIK SIPIL JURUSAN TEKNIK FAKULTAS SAINS DAN TEKNIK UNSOED

TAHUN 2011

Introduction

All the measurable effects of a change of stress, such ascompression, distortion and a change in the shearingresistance are exclusively due to changes in effectivestress… every investigation of the stability of a saturatedbody of earth requires the knowledge of both the totaland the neutral stresses

(Terzaghi, 1936)

Introduction

“The loss of weight of a body submerged in water is equal to the weight of water displaced, and that a floating body displaces its own weight of water.”

Archimedes (287-212 BC)

Concept

Soil is a multi phase systemTo perform any kind of analysis - we must

understand stress distributionThe concept of soil stress:

• The soil is “loaded” (e.g. footing, own weight of soil)

• The resulting stress is transmitted to the soil mass

• The soil mass supports those stresses at the point to point contacts of the individual soil grains

Concept

This total stress can be visualized to consist of TWO components(1)the pressure upon the soil skeletal

component, called the effective stress 'and,(2)the pressure from the water component in the

voids continuum, called the pore water pressure u, also known as the neutral stress.

Equation

Where g'= gsat - gw is the buoyant or submerged unit weight of soil.

Bina Nusantara

Example

Bina Nusantara

Example

Bina Nusantara

Example

Plot the variation of total and effective vertical stresses, and pore water pressure with depth for the soil profile shown below

Bina Nusantara

Example

Bina Nusantara

Example

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