GEOTECHNICAL ENGINEERING ECG 503 LECTURE NOTE 12 TOPIC

LEARNING OUTCOMES Learning outcomes: At the end of this lecture/week the students would be

TOPIC TO BE COVERED q Mechanical Methods and Objective; Stone Column, Dynamic Compaction, Vibrofloatation

Vibroflotation Suitable for granular soils Practiced in several forms: Ø vibro–compaction Ø stone columns

GENERAL BACKGROUND OF SOFT CLAY Malaysia Coastal Area – Not fully developed Soft clay

The soft clay have been a source of difficulties for many years. The soft

TWO DISTINCT ATOMIC STRUCTURAL UNITS hydroxyl or oxygen aluminium or magnesium silicon 0. 26

Micro-fabric particles in natural clay. Flocculated Dispersed

Ground Improvements for Soft Clay • Stone Column (Vibro-Replacement) • Prefabricated Vertical Drain •

Vibro-Replacement • Also known as stone column. The technique are similar to vibroflotation/vibrocompaction except

Soil Layer -Increase in density - Increase in bearing capacity - Radial drainage (help

Stone Columns vibrator makes a hole in the weak hole backfilled . . and

EXAMPLE OF CASE STUDY FOR GROUND IMPROVEMENT METHODS ON SOFT CLAY

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GEOTECHNICAL ENGINEERING ECG 503 LECTURE NOTE 12 TOPIC : 4. 0 GROUND IMPROVEMENT TECHNIQUES 09 OCTOBER 2008

LEARNING OUTCOMES Learning outcomes: At the end of this lecture/week the students would be able to: q Understand natural slope and made engineered soil slope assessment which include rainfall induced failure and role of suction.

TOPIC TO BE COVERED q Mechanical Methods and Objective; Stone Column, Dynamic Compaction, Vibrofloatation and Vibro Compaction. q Physical and Chemical Methods and objective; Grouting and cement column q Hydraulic Methods and Objective of Vertical Drain and Preloading

Vibroflotation Suitable for granular soils Practiced in several forms: Ø vibro–compaction Ø stone columns Ø vibro-replacement Vibroflot (vibrating unit) Length = 2 – 3 m Diameter = 0. 3 – 0. 5 m Mass = 2 tonnes (lowered into the ground and vibrated)

Vibroflotation

GENERAL BACKGROUND OF SOFT CLAY Malaysia Coastal Area – Not fully developed Soft clay usually located around the coastal area

The soft clay have been a source of difficulties for many years. The soft soil can cause settlement which can give a lot of problem and damage in several way. This is the reason why Malaysia’s coastal areas are not generally developed

TWO DISTINCT ATOMIC STRUCTURAL UNITS hydroxyl or oxygen aluminium or magnesium silicon 0. 26 nm Silicon Tetrahedron 0. 29 nm Aluminium Octahedron

Micro-fabric particles in natural clay. Flocculated Dispersed

Flaky shape Plate like structure

ION EXCHANGE

Ground Improvements for Soft Clay • Stone Column (Vibro-Replacement) • Prefabricated Vertical Drain • Cement Column

VIBRO-REPLACEMENT (STONE COLUMN)

Vibro-Replacement • Also known as stone column. The technique are similar to vibroflotation/vibrocompaction except the granular fill materials which used is sand is replaced by gravel stone sizes ranging from 50 mm to 100 mm

Soil Layer -Increase in density - Increase in bearing capacity - Radial drainage (help to improve settlement) - Shear strength of soil improve - Reinforcing the soil by applying rigid member (stone column) inside the soil