Analysis and Design of Piles

This paper presents the heave behaviour of expansive clay reinforced with Synthetic-fibres. Expansive clay is common to many parts of central and southern India, as well as elsewhere in the world. It has caused significant structural damage to an alarming number of buildings, particularly light weight structures and pavements. The pressures generated by swelling of clay can be devastating to the foundation if not managed properly. The expansive potential of soil varies dramatically from one season to another at any site due to the change in moisture content, which is the driving force in swell/shrink cycle. In this study, research has been carried out to study the effect of Synthetic-Fibers (Polypropylene and Polyester fibers) in curbing the swelling tendency of expansive clays. The behavioral changes in the soil samples were determined using One Dimensional swell-consolidation tests. In addition, the strength characteristics of the soil were also determined using Unconfined Compressive Strength (UCS) tests and California Bearing Ratio (CBR) tests for varied range of percentages of Synthetic-Fibers induced (i.e., from 0.2% to 0.8%). The swell-consolidation and strength parameters of soil are accomplished for varied Synthetic-Fibers and it is observed that the swell pressure has decreased by addition of fibers where as the voids ratio has increased on addition of Synthetic-fibers. The UCS and CBR of the soil have increased by increasing the proportion of fibres.

The assessment of the allowable bearing load of bored piles 'floating' in stiff clay is a standard engineering task. Although the soil mechanics is universal, engineers designing structures in different parts of the world will need to take into account the pertinent codes of practice. It will be helpful to compare such codes, especially in relation to their treatment of uncertainty in the design of bored piles. This paper presents a series of design calculations for a real set of geotechnical data using four international codes of practice: the Australian, American, European and Russian codes. The National Annexes of Ireland, the Netherlands and the UK are used in conjunction with the European code. This selection of countries covers the three Eurocode 7 design approaches (DA1, DA2 and DA3). A non-codified design method is used to provide a base case for comparative purposes with the six codified calculations. A companion paper investigates the issues of soil mechanics in pile design methods, uncertainty in soil parameters and settlement criteria.