The response of stone columns under the cyclic loading

Ashour, Samir (2016). The response of stone columns under the cyclic loading. University of Birmingham. Ph.D.

Preview

Ashour16PhD.pdf
PDF - Accepted Version
Download (5MB)

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:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):