Click the title below to display the complete page!
If the blasting is carried out carefully so as to avoid damage to the rock as far as possible and if the work is supported immediately, the average structure of the rock described here has very little effect on the deformations and consequently on the stress on the support. The movements of fragments in the rock are limited to a marginal zone of about 1/S of the diameter of the excavation. Outside this zone, the maximum shear strength is clearly maintained along the cracks and fissures. About the same conclusions were reached from measurements made during the construction of the Waldeck II Cavern . It will be of great interest for generally applicable data for certain types of terrain to be obtained from further systematic observations. In such observations, the ratio between the average fissure spacing and the dimensions of the excavation should be taken into account. The investigations also show clearly that the greatest attention must be paid to individual fault zones of a serious nature. In such zones, special local precautions should be taken.
Authors:Amstad, Christian and Kovári, Kalman and Necas, J.
Index Terms:design; underground openings; support; Displacement measurements; rock; TunnelingGroup
Further Information:Date published: 1975