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The damage index is a crucial controlling parameter for rock mass strength and deformation in civil, geological and mining engineering projects. In this study, a new method was proposed for computing the damage index of a rock mass based on the field point load strength. This method provides a strength ratio whose numerator is the point load strength (PLS) of splitting along the pre-existing joint and whose denominator is the PLS of intact rock failure. To validate this method, the authors derived a relationship between the damage index and the integrality coefficient using an empirical relation. Moreover, numerous experimental tests were conducted, including P-wave testing and on-site point load testing. Finally, linear regression analysis was performed to analyse the correlation between the new damage index D R and the integrality coefficient K V . This study demonstrates that the presented new method is sensitive to both plasticity and damage in estimating the damage degree of rock masses in underground excavation and tunnel engineering.

In this paper, the mechanical parameters of the grouting consolidation body on the rock block are studied using the Acoustic velocity test case and the revised Hoek-Brown failure criterion in underground metal mines. In light of the hidden resources in the collapsed area of the underground metal mine, the intact rock drilling core cannot be obtained to perform the mechanical test because of extreme damage or because it is completely broken. Therefore, pure cement grouting is used to reinforce the extremely broken rock mass within the collapsed area of the hidden resources. The RQD value and water permeability are tested to indicate that cement pastes can fill the cracks in broken rock blocks and can improve the integrity of the broken rock mass. To detect the grouting consolidation effect of the fractured rock mass and evaluate the mechanical parameters of the consolidation body, a nondestructive test is applied to measure the Acoustic velocity of the consolidation body after grouting. Initially, the measured Acoustic velocity is adopted to calculate the damage index (or integrity index), which is approximately equivalent to the disturbance factor. Then, the modified Hoek-Brown failure criterion is used to evaluate the mechanical parameters of the grouting consolidation body. Finally, to verify this method, the mechanical parameters of the rock mass are also obtained by a laboratory test. The outcomes show that the current research can serve as a practical method when evaluating rock mass quality by the grouting treatment.INDEX TERMS Acoustic waves, civil engineering, consolidation body, Hoek Brown criteria, Young's modulus.

A novel Mamdani fuzzy classifier based on improved chaos immune algorithm is developed, in which bilateral Gaussian membership function parameters are set as constraint conditions and the indexes of fuzzy classification effectiveness and number of correct samples of fuzzy classification as the subgoal of fitness function. Moreover, Iris database is used for classification effectiveness simulation experiment. The results show that Mamdani fuzzy classifier based on improved chaos immune algorithm can effectively improve the prediction accuracy of classification of data sets with noises and outliers.