Use of Laser and Surface Active Agents for Excavation in Hard Rocks
Authors: Moavenzadeh F. , McGarry F.J. , Williamson R.B. 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
This paper was prepared for the 43rd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Sept. 29-Oct. 2, 1968. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
The surface active agents and continuous gas lasers are found to be effective in reducing the strength of hard rocks when tested in bending. The observed reduction in strength, when the rock specimens are subjected to laser irradiation is due to thermal stresses developed within the specimens. Stress activated corrosion is considered to be the main cause of loss of strength when surfactants are used.

Introduction
Deep tunnels are suggested as a possible guideway for high speed ground possible guideway for high speed ground transport systems in the Northeast corridor to relieve the frequent air and land transportation congestion. The great flexibility in route location, lack of any significant interference with existing activities, excellent isolation and safety to public, and negligible cost of right of way have made the tunnelling an attractive possibility for such a guideway.
One of the major problems associates with the construction of a deep tunnel is the tunnel driving technique and the slow rate of advance of the heading associated with such an operation, especially in hard rocks.
The tunnelling operation in hard rocks basically involves fracturing and disintegration of rock masses and the removal of debris. Slowness of the conventional method of tunnelling is primarily due to the discontinuous nature primarily due to the discontinuous nature of the operation, whereby different steps of drilling, charging, blasting, ventilating and removal of debris have to be performed in a repetitive manner. A performed in a repetitive manner. A variety of techniques of breaking rock masses is suggested in the literature which attempt to provide a continuous tunnelling operation or to reduce the number of steps in conventional tunnel driving. It is apparent from a review of these methods, however, that a fundamental understanding of the failure of rocks and the factors controlling it is important for the development of a rapid method of excavation in hard rocks.