Rock mass quality evaluation of underground engineering based on RS-TOPSIS method

A method of technique for order preference by similarity to ideal solution (TOPSIS) was used to classify the quality of the rock mass in underground engineering. Five indexes, i.e., rock quality designation, uniaxial compressive strengthen, rock mass integrality coefficient, strengthen coefficient of structural plane and seepage measurement of groundwater were selected to be the evaluation indicators. Based on rough set theory (RS), the significance of evaluation indicators was confirmed by calculating rough dependability between evaluation indicators and evaluation results. 17 samples of the first stage project in Guangzhou pump accumulator electricity station and 13 samples produced by the interpolation method were taken as the training samples, five typical samples of different grades were created depending on the lower interval limits of single index evaluation, the classification was decided by calculating the relative closeness of typical samples to the positive ideal solution, and RS-TOPSIS model was established for the rock mass quality evaluation in underground engineering. Each of the 30 samples was tested according to the model, and the correct rate is 96.7%. And then the model was applied to predict the evaluation of second project. The results show that the evaluation results using RS-TOPSIS method agreed well with those of the catastrophe progression method, artificial neural network (ANN) method and support vector machine (SVM) method. The proposed method is of practical value and can be used to evaluate the quality of rock mass in underground engineering.