A Fisher discriminant analysis (FDA) model for the prediction of classification of rockburst in deep-buried long tunnel was established based on the Fisher discriminant theory and the actual characteristics of the pro...A Fisher discriminant analysis (FDA) model for the prediction of classification of rockburst in deep-buried long tunnel was established based on the Fisher discriminant theory and the actual characteristics of the project.First, the major factors of rockburst,such as the maximum tangential stress of the cavern wall σ_θ, uniaxial compressive strength σ_c, uniaxial tensile strength σ_t, and the elastic energy index of rock W_(et), were taken into account in the analysis.Three factors, Stress coefficient σ_θlσ_c, rock brittleness coefficient σ_c/σ_t, and elastic energy index W_(et), were defined as the criterion indices for rockburst prediction in the proposed model.After training and testing of 12 sets of measured data, the discriminant functions of FDA were solved, and the ratio of misdiscrimination is zero.Moreover, the proposed model was used to predict rockbursts of Qinling tunnel along Xi'an-Ankang railway.The results show that three forecast results are identical with the actual situation.Therefore, the prediction accuracy of the FDA model is acceptable.展开更多
In the geostress measurement for Niba Mountain on Ya＇an-Lugu Expressway, results of Kaiser effect tests combined with focal mechanism solution were compared with those obtained by hydraulic fracturing method, both of...In the geostress measurement for Niba Mountain on Ya＇an-Lugu Expressway, results of Kaiser effect tests combined with focal mechanism solution were compared with those obtained by hydraulic fracturing method, both of which are basically coincident. It is shown that the principal stress increases with burial depth ; the maximum principal stress is about 45 MPa, which is larger near fault zones because of stress concentration, and its direction ranges from N20°W to N75°W.展开更多
Imaging the wave velocity field surrounding a borehole while drilling is a promising and urgently needed approach for extending the exploration range of the borehole point.This paper develops a drilling process detect...Imaging the wave velocity field surrounding a borehole while drilling is a promising and urgently needed approach for extending the exploration range of the borehole point.This paper develops a drilling process detection(DPD)system consisting of a multifunctional sensor and a pilot geophone installed at the top of the drilling rod,geophones at the tunnel face,a laser rangefinder,and an onsite computer.A weighted adjoint-state first arrival travel time tomography method is used to invert the P-wave velocity field of rock mass while borehole drilling.A field experiment in the ongoing construction of a deep buried tunnel in southwestern China demonstrated the DPD system and the tomography method.Time-frequency analysis of typical borehole drilling detection data shows that the impact drilling source is a pulse-like seismic exploration wavelet.A velocity field of the rock mass in a triangular area defined by the borehole trajectory and geophone receiving line can be obtained.Both the borehole core and optical image validate the inverted P-wave velocity field.A numerical simulation of a checkerboard benchmark model is used to test the tomography method.The rapid convergence of the misfits and consistent agreement between the inverted and observed travel times validate the P-wave velocity imaging.展开更多
基金Supported by the National 11th Five-Year Science and Technology Supporting Plan of China(2006BAB02A02)Central South University Innovation funded projects (2009ssxt230, 2009ssxt234)
文摘A Fisher discriminant analysis (FDA) model for the prediction of classification of rockburst in deep-buried long tunnel was established based on the Fisher discriminant theory and the actual characteristics of the project.First, the major factors of rockburst,such as the maximum tangential stress of the cavern wall σ_θ, uniaxial compressive strength σ_c, uniaxial tensile strength σ_t, and the elastic energy index of rock W_(et), were taken into account in the analysis.Three factors, Stress coefficient σ_θlσ_c, rock brittleness coefficient σ_c/σ_t, and elastic energy index W_(et), were defined as the criterion indices for rockburst prediction in the proposed model.After training and testing of 12 sets of measured data, the discriminant functions of FDA were solved, and the ratio of misdiscrimination is zero.Moreover, the proposed model was used to predict rockbursts of Qinling tunnel along Xi'an-Ankang railway.The results show that three forecast results are identical with the actual situation.Therefore, the prediction accuracy of the FDA model is acceptable.
基金Western Region Transportation Scientificand Technological Project of Transportation Ministry(No.2006318000104)Graduate Innovation Fund of South-west Jiaotong University in 2008
文摘In the geostress measurement for Niba Mountain on Ya＇an-Lugu Expressway, results of Kaiser effect tests combined with focal mechanism solution were compared with those obtained by hydraulic fracturing method, both of which are basically coincident. It is shown that the principal stress increases with burial depth ; the maximum principal stress is about 45 MPa, which is larger near fault zones because of stress concentration, and its direction ranges from N20°W to N75°W.
基金Supported by the New Century Excellent Talent Foundation from MOE of China（NCET-09-0844） the National Natural Science Foundation of China （50804060, 50921063）
基金the support of the National Natural Science Foundation of China(Nos.42207211,42202320 and 42172296)Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University(No.KLE-TJGE-G2304).
文摘Imaging the wave velocity field surrounding a borehole while drilling is a promising and urgently needed approach for extending the exploration range of the borehole point.This paper develops a drilling process detection(DPD)system consisting of a multifunctional sensor and a pilot geophone installed at the top of the drilling rod,geophones at the tunnel face,a laser rangefinder,and an onsite computer.A weighted adjoint-state first arrival travel time tomography method is used to invert the P-wave velocity field of rock mass while borehole drilling.A field experiment in the ongoing construction of a deep buried tunnel in southwestern China demonstrated the DPD system and the tomography method.Time-frequency analysis of typical borehole drilling detection data shows that the impact drilling source is a pulse-like seismic exploration wavelet.A velocity field of the rock mass in a triangular area defined by the borehole trajectory and geophone receiving line can be obtained.Both the borehole core and optical image validate the inverted P-wave velocity field.A numerical simulation of a checkerboard benchmark model is used to test the tomography method.The rapid convergence of the misfits and consistent agreement between the inverted and observed travel times validate the P-wave velocity imaging.
