Hasan Gerçek

Effect of Poisson's ratio on the normalized radial displacements occurring around the face of a circular tunnel

Abstract The distribution of displacements occurring around the advancing face of a tunnel is one of the widely discussed topics in tunnelling. Unavailability of a closed-form solution for this problem has directed the researchers to the utilization of numerical analyses mainly. In this study, a three-dimensional finite difference stress analysis program, i.e. FLAC3D, has been employed for determining the variation of radial boundary displacements along the longitudinal direction of a circular tunnel located in a hydrostatic in situ stress field. According to the results for a linear elastic material behavior, the normalized radial displacements occurring in the vicinity of the face are affected by Poissons ratio of the surrounding medium. In addition, it has been noted that, depending on Poissons ratio, the value of elastic pre-deformation occurring at the face ranges between 20 and 30% of the final tunnel deformation occurring far from the face. Furthermore, expressions obtained by non-linear curve fitting are presented for the normalized radial displacements occurring ahead of and behind the excavation face of the tunnel.

An elastic solution for stresses around tunnels with conventional shapes

Abstract An analytical solution has been developed for calculation of elastic stresses occurring around tunnels or galleries with conventional shapes which are frequently used in mining and civil engineering. Basically, the cross sections considered in the solution have one vertical axis of symmetry, and the roof is arched while the floor may be flat or parabolic. The solution is obtained by using the conformal mapping technique of the complex variable method. After a brief explanation of the method, explicit formulation is presented, and equations for the induced stresses are given. Using the solution, distribution of stresses around the tunnels is determined for various in situ stress conditions. Finally, potential applications of the solution are demonstrated by examples in rock engineering.

Stability considerations for underground excavation intersections

Abstract Structural stability of excavation intersections is a prerequisite for the proper functioning of vital rooms and tunnels in mining. The potential for instability at intersections is more pronounced for several reasons, the most important being the high induced stresses occurring in the surrounding rock. In this paper, induced stresses and their three-dimensional extent are estimated from information available in the literature. In addition, design and support aspects of such intersections are examined with reference to practical considerations.

Sinking of the deepest shaft in Turkey

Abstract This paper describes the sinking of New Kozlu Shaft in the Zonguldak Coalfield, Turkey. This 6.5 m diameter shaft, with its final depth of 913 m has become the deepest shaft sunk in the country. The construction which lasted about eleven and a half years is reviewed in two separate sinking stages carried out by the coal company and a contracting firm. Also, comparisons of the equipment and sinking operations in these stages are given.

Calculation of elastic boundary stresses for rectangular underground openings

Abstract An analytical solution has been presented for calculation of elastic tangential stresses occurring on the boundary of an underground opening having an approximately rectangular cross section. It can be applied to an opening located in a general biaxial in-situ stress field and width-to-height ratio of the opening can take almost any value. The method of solution involves the complex variable method of plane elasticity and the conformal mapping technique.