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The response of stone columns under the cyclic loading

Ashour, Samir (2016)
Ph.D. thesis, University of Birmingham.

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Abstract

Soft clay soils in railway track can be problematic as, unless they are treated, they can result in increased deformation of track. This will inheritably mean lower track speed. A number of techniques including stone columns are available for improving strength of weak soils.

The use of stone columns, for improving both bearing capacity and settlement is well rehearsed for static loading; little is understood about their response, when subjected to cyclic loading. This study is focused on investigating the behaviour of stone columns when subjected to cyclic loading as in railway tracks based on a laboratory scale investigation.

A series of monotonic and cyclic loading conditions were undertaken on two laboratory models undrained triaxial and large scale model. Tests were conducted on both soft soils (no column) and soil/ stone column composite (reinforced with 28 mm diameter stone columns). All tests were performed on normally consolidated specimens of soft clay (c\(_u\) ≈ 12 kPa).

The effect of both cyclic stresses and loading frequency on the permanent deformation, soils stiffness and pore water pressure generation were investigated.

It was found that threshold dynamic stress of soil for cyclic loading increased from 50 kPa for soil only to 60 kPa for soil with stone column. This is equivalent to CSR of 0.7.

Changes in frequencies tested did not significantly influence the permanent strain of reinforced soil, but these changes do affect the stiffness. Stone columns also helped reduce pore water pressure build up under cyclic loading by providing a drainage path.

Type of Work:Ph.D. thesis.
Supervisor(s):Ghataora, G.S. (Gurmel S.) and Jefferson, Ian
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Civil Engineering
Subjects:GB Physical geography
TA Engineering (General). Civil engineering (General)
Institution:University of Birmingham
ID Code:6462
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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