Method for constructing an underground tunnel or hole to create an impervious plug for the storage of hazardous, particularly radioactive, waste

Abstract

A method for the construction of a gallery or a shaft leading to an underground facility intended for the medium- or long-term storage of hazardous wastes, including an excavation of at least one determined length of the gallery carried out by using a method of prior preparation by protection or reinforcement of the materials prior to the excavation, in a part of the gallery intended to subsequently receive a plug that is sealed to liquids or gasses.

1 . A method for the construction of a gallery or a shaft leading to an underground facility intended for the medium- or long-term storage of hazardous wastes, comprising: an excavation of at least one determined length of said gallery carried out by using a method of prior preparation by protection or reinforcement of the materials prior to the excavation, in a part of said gallery intended to subsequently receive a plug that is sealed to liquids or gasses. 
     
     
         2 . The method of  claim 1 , wherein the prior preparation method comprises a prior protection by installing in the material to be excavated, in front of the working face of the gallery, elements positioned so as to support said gallery during the subsequent progression of said working face. 
     
     
         3 . The method of  claim 2 , wherein the support elements comprise elements in the form of a frustum of a cone, positioned so as to form a shell completely or partially surrounding the periphery of the gallery in the process of excavation. 
     
     
         4 . The method of  claim 1 , wherein the preparation method comprises a prior reinforcement by installation in the material to be excavated, in front of the working face of the gallery in the process of excavation, expendable means of anchoring said working face over a determined depth, beyond the surface of said working face. 
     
     
         5 . The method of  claim 4 , wherein the anchoring means comprise rock bolts which are expendable during the excavation, positioned in a manner substantially perpendicular to the working face or diverging slightly in the direction of the excavation. 
     
     
         6 . The method of  claim 1 , wherein that the prior preparation method comprises a prior reinforcement by freezing the materials located in front of the working face of progression of the gallery in the process of excavation. 
     
     
         7 . A method for the construction of a gallery leading to an underground facility intended for the medium- or long-term storage of hazardous wastes, comprising: a combination of a prior protection by installing in the material to be excavated, in front of the working face of the gallery, elements positioned so as to support said gallery during the subsequent progression of said working face and a prior reinforcement according to  claim 4  for the excavation of a single part of said gallery intended to subsequently receive a plug that is sealed to liquids or gasses. 
     
     
         8 . The method of  claim 7  wherein the prior preparation method comprises an installation in the material to be excavated, in front of the working face of progression of the gallery in the process of excavation:
 on the one hand, of elements positioned so as to support said gallery during the subsequent progression of said working face, and 
 on the other hand, of means of anchoring said material over a determined depth beyond the surface of said working face. 
 
     
     
         9 . An underground facility intended for the medium- or long-term storage of hazardous wastes, comprising: at least one part of the gallery receiving, or intended to receive, a sealing plug and constructed by a method according to  claim 1 . 
     
     
         10 . The method for testing the sealing performance indicators of at least one part of a gallery, called a treated gallery, obtained by an excavation method according to  claim 1 , said testing method comprising the following steps:
 installing in said treated part at least one sealing plug surrounded on each of its two sides by at least one upstream and downstream test chambers delimited by at least one upstream sealing plug and a downstream sealing plug;   creation of a pressure difference between said test chambers; and   measuring the pressure difference or the change in pressure difference between said test chambers.