The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks(well interlocked undisturbed rock mass with blocks formed by three or ...The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks(well interlocked undisturbed rock mass with blocks formed by three or less intersecting joints). A synthetic rock mass modelling(SRM) approach is employed to determine the mechanical properties of the rock mass. In this approach, the intact body of rock is represented by the discrete element method(DEM)-Voronoi grains with the ability of simulating the initiation and propagation of microcracks within the intact part of the model. The geometry of the preexisting joints is generated by employing discrete fracture network(DFN) modelling based on field joint data collected from the Brockville Tunnel using LiDAR scanning. The geometrical characteristics of the simulated joints at a representative sample size are first validated against the field data, and then used to measure the rock quality designation(RQD), joint spacing, areal fracture intensity(P21), and block volumes. These geometrical quantities are used to quantitatively determine a representative range of the geological strength index(GSI). The results show that estimating the GSI using the RQD tends to make a closer estimate of the degree of blockiness that leads to GSI values corresponding to those obtained from direct visual observations of the rock mass conditions in the field. The use of joint spacing and block volume in order to quantify the GSI value range for the studied rock mass suggests a lower range compared to that evaluated in situ. Based on numerical modelling results and laboratory data of rock testing reported in the literature, a semi-empirical equation is proposed that relates the rock mass modulus to confinement as a function of the areal fracture intensity and joint stiffness.展开更多
This study simulated and predicted the runoff of the Aksu River Basin, a typical river basin supplied by snowmelt in an arid mountain region, with a limited data set and few hydrological and meteorological stations. T...This study simulated and predicted the runoff of the Aksu River Basin, a typical river basin supplied by snowmelt in an arid mountain region, with a limited data set and few hydrological and meteorological stations. Two hydrological models, the snowmelt-runoff model (SRM) and the Danish NedbФr-AfstrФmnings rainfall-runoff model (NAM), were used to simulate daily discharge processes in the Aksu River Basin. This study used the snow-covered area from MODIS remote sensing data as the SRM input. With the help of ArcGIS software, this study successfully derived the digital drainage network and elevation zones of the basin from digital elevation data. The simulation results showed that the SRM based on MODIS data was more accurate than NAM. This demonstrates that the application of remote sensing data to hydrological snowmelt models is a feasible and effective approach to runoff simulation and prediction in arid unguaged basins where snowmelt is a major runoff factor.展开更多
基金the Nuclear Waste Management Organization (NWMO) of Canadathe National Science and Engineering Research Council (NSERC)+1 种基金the Canadian Ministry of National Defence (DND)the RMC Green Team for funding this research
文摘The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks(well interlocked undisturbed rock mass with blocks formed by three or less intersecting joints). A synthetic rock mass modelling(SRM) approach is employed to determine the mechanical properties of the rock mass. In this approach, the intact body of rock is represented by the discrete element method(DEM)-Voronoi grains with the ability of simulating the initiation and propagation of microcracks within the intact part of the model. The geometry of the preexisting joints is generated by employing discrete fracture network(DFN) modelling based on field joint data collected from the Brockville Tunnel using LiDAR scanning. The geometrical characteristics of the simulated joints at a representative sample size are first validated against the field data, and then used to measure the rock quality designation(RQD), joint spacing, areal fracture intensity(P21), and block volumes. These geometrical quantities are used to quantitatively determine a representative range of the geological strength index(GSI). The results show that estimating the GSI using the RQD tends to make a closer estimate of the degree of blockiness that leads to GSI values corresponding to those obtained from direct visual observations of the rock mass conditions in the field. The use of joint spacing and block volume in order to quantify the GSI value range for the studied rock mass suggests a lower range compared to that evaluated in situ. Based on numerical modelling results and laboratory data of rock testing reported in the literature, a semi-empirical equation is proposed that relates the rock mass modulus to confinement as a function of the areal fracture intensity and joint stiffness.
基金Acknowledgements The authors gratefully acknowledge the financial support from the State Key Research Development Program of China (Grant No. 2016YFC0600705), the National Natural Science Foundation of China (Grant Nos. 51674251, 51727807, 51374213), the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No. 51125017), the Fund for Creative Research and Development Group Program of Jiangsu Province (Grant No. 2014-27), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (Grant No. PAPD2014), and an open project sponsored by the State Key Labo- ratory for Geomechanics and Deep Underground Engineering (Grant SKLGDUE K1318) for their financial support.
基金supported by the National Basic Research Program of China(Grant No.2006CB400502)the World Bank Cooperative Project(Grant No.THSD-07)the 111 Program of the Ministry of Education and the State Administration of Foreign Expert Affairs,China(Grant No.B08048)
文摘This study simulated and predicted the runoff of the Aksu River Basin, a typical river basin supplied by snowmelt in an arid mountain region, with a limited data set and few hydrological and meteorological stations. Two hydrological models, the snowmelt-runoff model (SRM) and the Danish NedbФr-AfstrФmnings rainfall-runoff model (NAM), were used to simulate daily discharge processes in the Aksu River Basin. This study used the snow-covered area from MODIS remote sensing data as the SRM input. With the help of ArcGIS software, this study successfully derived the digital drainage network and elevation zones of the basin from digital elevation data. The simulation results showed that the SRM based on MODIS data was more accurate than NAM. This demonstrates that the application of remote sensing data to hydrological snowmelt models is a feasible and effective approach to runoff simulation and prediction in arid unguaged basins where snowmelt is a major runoff factor.