Rapid intelligent evaluation method and technology for determining engineering rock mass quality

The evaluation of engineering rock mass quality is fundamental work for the engineering activities of rock mass.The increasing scale of rock mass engineering necessitates higher intelligence,timeliness,and accuracy in engineering rock mass quality evaluation.As the core aspects of engineering rock mass quality evaluation,the structural characteristics,mechanical characteristics,and quality classification of rock mass have been innovated in recent years.The non-contact measurement technology for rock mass structure and rapid interpretation of rock mass structure information enables the intelligent extraction and analysis of rock mass structure parameters.The modular backpack laboratory system of rock mechanics provides an effective means to acquire rock mechanical parameters on-site conveniently.The theory of statistical mechanics of rock mass(SMRM)integrates various factors such as the rock mass properties,geological environment,and engineering disturbance,providing a theoretical basis for accurately evaluating the weakening and anisotropy of rock mass.The cloud computing platform established based on SMRM can provide technical support for the rapid calculation of rock mass parameters and instant evaluation of the rock mass quality.The development of intelligent evaluation method and technology is altering the conventional technical state of qualitative and semi-quantitative evaluation of engineering rock mass quality,supporting the realization of rock mass engineering construction with intellectualization and informatization.

Evolution process of rock mass engineering system using systems science

The rock mass engineering system （RMES） basically consists ofrock mass engineering （RME）, water system and surroundingecological environments, etc. The RMES is characterized by nonlinearity,occurrence of chaos and self-organization （Tazaka, 1998;Tsuda, 1998; Kishida, 2000）. From construction to abandonmentof RME, the RMES will experience four stages, i.e. initial phase,development phase, declining phase and failure phase. In thiscircumstance, the RMES boundary conditions, structural safetyand surrounding environments are varied at each phase, so arethe evolution characteristics and disasters （Wang et al., 2014）.

Dynamic discrete element method and its application in rock mass engineering

Based on conventional discrete element method, the idea and calculating method of dynamic discrete element (DDEM) was proposed, and a relevant program was developed. The application of the method is presented in rock mechanics and engineering, which indicates that the method can be widely used in dynamic response and stability analysis of jointed rockmass under dynamic load. [

Engineering rock mechanics practices in the underground powerhouse at JinpingⅠhydropower station

Based on the analyses of data obtained from the underground powerhouse at Jinping I hydropower station, a comprehensive review of engineering rock mechanics practice in the underground powerhouse is first conducted. The distribution of strata, lithology, and initial geo-stress, the excavation process and corresponding rock mass support measures, the deformation and failure characteristics of the surrounding rock mass, the stress characteristics of anchorage structures in the cavern complex, and numerical simulations of surrounding rock mass stability and anchor support performance are presented. The results indicate that the underground powerhouse of Jinping I hydropower station is characterized by high to extremely high geo-stresses during rock excavation. Excessive surrounding rock mass deformation and high stress of anchorage structures, surrounding rock mass unloading damage, and local cracking failure of surrounding rock masses, etc., are mainly caused by rock mass excavation. Deformations of surrounding rock masses and stresses in anchorage structures here are larger than those found elsewhere： 20% of extensometers in the main powerhouse record more than 50 mm with the maximum at around 250 mm observed in the downstream sidewall of the transformer hall. There are about 25% of the anchor bolts having recorded stresses of more than 200 MPa. Jinping I hydropower plant is the first to have an underground powerhouse construction conducted in host rocks under extremely high geo-stress conditions, with the ratio of rock mass strength to geo-stress of less than 2.0. The results can provide a reference to underground powerhouse construction in similar geological conditions.

A brief introduction to disaster rock mass mechanics

Rock mass mechanics can be classified into engineering rock mass mechanics and disaster rock mass mechanics based on science and application.Their conception,object,scientific essence and application were elaborated.The connotation,studying method and theoretical framework of disaster rock mass mechanics were described.Disaster rock mass mechanics is a strongly nonlinear discipline which is a strong tool to study natural and artificially-induced disasters.The rock mass system where disasters happen exhibits extremely spatial-temporal nonlinearity in the critically unstable state.Hence,the potentially effective prediction and forecasting of disasters depends on statistical analysis of highly probable events.The direction of efforts for predicting and forecasting disasters could be to find the quantitative or semi-quantitative relationship between physical and biological information and instability of rock mass system.