In order to investigate the mechanism of grouting strengthening the fault gouge of Yonglian tunnel,a test system including a module of grouting technology,a module of injection medium and a module of information collection was designed. The orthogonal uniaxial compression tests,tests for the typical characteristics of pulp-rock interfaces and the scanning electrum micrographs(SEM) tests for fault gouge were carried out. The uniaxial compressive strength of the fault gouge was increased by 181%–2 535% after ...