الفهرس Only 14 pages are availabe for public view
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Abstract
The use of tunnels in urban areas has gained much popularity in recent years in transportation and in infrastructure projects especially in heavily populated cities, where the available areas above-ground are limited. Tunneling is a relatively complicated engineering problem. The degree of complexity gets higher when two tunnels are closely spaced, which is a typical case used in transportation or in infrastructure projects.
The main objective of this research was to develop a numerical model to study the behavior of twin tunnels constructed using open face machines in stiff clayey soils. The numerical analysis results were compared with field measurements to investigate the possibility of efficient back analysis of tunneling projects using such techniques and to validate the applicability of the numerical model used in this research for future cases with similar tunneling and geological conditions. An extensive parametric study was also performed to identify the main variables that govern the behavior of twin tunnels and to quantify their impact on tunnel and ground behavior.
The study validated the concept of using stress release factor to simulate three dimensional soil arching at tunnel face and ground relaxation prior to lining installation. The study also provided an assessment of zone of stress disturbance around twin tunnels constructed in stiff clay in addition to estimates of associated displacements and lining straining actions. The results of the parametric study were used to develop an estimate of the separation distance between twin tunnels beyond which interaction between tunnels is expected to be of minor influence.