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Thesis defences

PhD Oral Exam - Ibrahim Mashhour, Civil Engineering

Experimental Study on Negative Skin Friction on Piles in Collapsible Soils Due to Inundation


Date & time
Tuesday, October 6, 2015
2 p.m. – 5 p.m.
Cost

This event is free

Organization

School of Graduate Studies

Contact

Sharon Carey
514-848-2424, ext. 3802

Wheel chair accessible

Yes

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Collapsible soil is a special type of soil, known as a problematic soil. It possesses a high strength when it is dry and loses its strength and exhibits substantial settlement when it is inundated. Collapsible soil is responsible for many foundation failures and loss of lives around the world. One of the common types of foundation in collapsible soil is the use of piles to penetrate this layer to a firm soil strata. Nevertheless, these piles will be subjected to negative skin friction during wetting of the collapsible soil, reducing the pile’s capacity and generate excessive settlements.

Researchers are facing serious challenges in dealing with piles in collapsible soils due to the complexity of the problem and the difficulties associated in modeling this behaviour numerically and experimentally. In the literature, limited investigations were reported dealing with pile foundations in collapsible soils subjected to inundation, nevertheless the outcome remained sketchy.

An experimental investigation was carried out to simulate the complex interactional behaviour between collapsible soil and piles during inundation from the top and the bottom of the collapsible soil layer, under a various loading and soil conditions. An experimental prototype setup was developed and calibrated in the laboratory for the case of a single pile penetrating a collapsible soil layer and resting on a rigid strata. The objective of the experimental investigation was to measure the negative skin friction acting on the pile’s shaft and accordingly the drag load for a give soil/geometry/loading conditions. Collapsible soils with different collapsible potential were determined in the laboratory by mixing kaoline with fine sand at predetermined ratios. Design theory was developed and recommended for practising use.


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