ABSTRACT:

Growing needs for modern transportation and utility networks have increased the demand for a more extensive and elaborate use of underground space. As a result, more underground projects have to be completed in a variety of ground conditions, including weak water bearing soils and soft rocks. Significant technological advances have rendered these projects possible, but have also given rise to new challenges as many of these projects have to be completed in difficult conditions, with very strict environmental constraints, particularly in urban areas where the potential impact of tunneling on existing structures is a major concern. This report addresses the main aspects of tunneling and underground works performed in soils and soft rocks. A summary is presented of the main features related to construction techniques, ground investigations, design methods, and instrumentation and monitoring practices, as well as of some of the more recent advances in these fields. Significant progress has been made in the area of soft ground tunneling over the past thirty years, partly because of advances in computer technologies. The scope of increasing difficult project conditions to be addressed requires that the best use be made of these technologies, as well as of lessons gained from past experience and current observational records.

1.0 INTRODUCTION

Growing needs for modern transportation and utility networks have given rise to an increased demand for a more extensive and elaborate use of underground space. Some of these projects are related to urban development, which requires the construction of more metro systems, underground water mains, gas pipes, telecommunication and electric power networks, as well as underground parking facilities. Other applications of underground construction include the crossing of natural barriers such as rivers and mountains that are found across the alignment of major road, motorway or railway link projects.

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