Sand columns stabilized with cement embedded in soft soil

Dissertant

Rajab, Nawras Abd Ali

Thesis advisor

al-Suudi, Namir K. S.
al-Qaysi, Muhammad Mustafa Mahmud

University

University of Technology

Faculty

-

Department

Department of Building and Construction Engineering

University Country

Iraq

Degree

Master

Degree Date

2013

English Abstract

Soft saturated soils are characterized by their low undrained shear strength and high compressibility.

These soils cover most likely the southern and middle parts of Mesopotamia.

Several improvement techniques are available to increase the bearing capacity, control settlement and accelerate the consolidation process of soft soils.

Among these techniques is the sand columns.

In principles, sand columns technique is very close to the well-known stone columns technique and the only difference is the backfill materials.

The present work focuses on improving the geotechnical properties of soft soils by implementing sand columns and sand columns stabilized with cement to provide stiffer inclusion in the bed of soft soil.

Sand columns stabilized with cement is an alternative approach to provide extra stiffness to the columns and hence provide extra improvement in terms of bearing capacity and compressibility.

Model tests were performed on soft soil reinforced with sand columns, sand columns stabilized with different percentages of Portland cement and cured for 7 and 28 days.

The investigation considered floating and end bearing types of columns.

A total number of 28 model tests were carried out on a soil with undrained shear strength ranging between (15-20) kPa.

The models consist of individual columns at area replacement ratio of (0.6) and length of column to diameter (L/D=6).

The model tests revealed optimum cement content for floating type was 9% for models cured for 7 days with bearing improvement ratio = 3.19 and 7% cement content for models cured for 28 days with bearing improvement ratio = 3.08; while end bearing type was 8% cement content for models cured for 7 days with bearing improvement ratio = 3.92.

The two types of model tests exhibited pronounced reduction in the settlement and revealed very low values of settlement reduction ratio.

Main Subjects

Civil Engineering

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-418251