Accession Number : AD0755536

Title :   Model Studies of Rock Bolted Tunnels in Brittle, and Plastic Ground.

Descriptive Note : Interim technical rept.,

Corporate Author : CALIFORNIA UNIV BERKELEY

Personal Author(s) : Bureau,Gilles J. ; Goodman,Richard E. ; Heuze,Francois E.

Report Date : NOV 1972

Pagination or Media Count : 101

Abstract : In this research project, two dimensional physical models simulating rock-bolted tunnels in jointed rock were loaded to failure. Observations allow comparisons to be made between relative efficiency of patterns of long versus short bolts for the specific geologic systems modelled: (1) a plastic material simulating shaley sediments; and (2) a brittle mix simulating more competent rock types. For each material, experiments were performed without bolts or joints; without bolts but with one set of joints; and with bolts and joints. The bolts proved to significantly reduce tunnel deformations and prevent falls of rock; but bolting did not reinforce the rock matrix. Failures of bolts were preceded by increase of bolt tension. The pattern of longer bolts proved more efficient than the pattern of shorter bolts. But neither pattern restored completely the portion of tunnel 'strength' removed by the introduction of the system of joints. The results were evaluated by dimensional analysis. (Author)

Descriptors :   (*JOINTS, PERFORMANCE(ENGINEERING)), (*ROCK, JOINTS), (*UNDERGROUND STRUCTURES, JOINTS), SHELTERS, BOLTED JOINTS, FAILURE(MECHANICS), DEFORMATION, LOADS(FORCES), TENSILE PROPERTIES, STRESSES, DAMAGE ASSESSMENT

Subject Categories : Geology, Geochemistry and Mineralogy
      Couplers, Fasteners, and Joints
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE