Hydraulic fracture is one of the key methods in well stimulation to increase production of oil and gas.Crack Opening Displacement(COD) is of great importance in this method since it is in direct relation with permeabi...Hydraulic fracture is one of the key methods in well stimulation to increase production of oil and gas.Crack Opening Displacement(COD) is of great importance in this method since it is in direct relation with permeability and production rate.In this paper COD is measured by a distinct element model which has been validated by an exact solution.A comprehensive study has been performed on confining pressure effect on COD which is neglected in the analytical solution.Numerical results showed that confining pressure considerably affects COD.A multi-parameter regression(considering effect of confining pressure,rock mass properties and fluid pressure) was performed on numerical results which resulted in an equation.The proposed equation considers the effect of confining pressure and its results are in good agreement with numerical results.展开更多
The distinct characteristic of subcritical propagation requires at least two control parameters to completely express expansion of cracks in the concrete.The basic definition of crack tip opening displacement(CTOD)is ...The distinct characteristic of subcritical propagation requires at least two control parameters to completely express expansion of cracks in the concrete.The basic definition of crack tip opening displacement(CTOD)is corrected based on the monitored variable of crack mouth opening displacement(CMOD).The improved CTOD criterion,called the double CTODd criterion,for the abnormality diagnosis of cracks in the concrete is constructed based on the fictitious crack model and linear asymptotic superposition assumptions of the concrete.The double CTODd criterion is verified using two specimens of three-point bending notched beam.The verification results are reasonable and correct.The establishment of the double CTODd criterion lays a solid theoretical foundation for the abnormality diagnosis of cracks in concrete structures(such as concrete dams)based on CMOD.展开更多
文摘Hydraulic fracture is one of the key methods in well stimulation to increase production of oil and gas.Crack Opening Displacement(COD) is of great importance in this method since it is in direct relation with permeability and production rate.In this paper COD is measured by a distinct element model which has been validated by an exact solution.A comprehensive study has been performed on confining pressure effect on COD which is neglected in the analytical solution.Numerical results showed that confining pressure considerably affects COD.A multi-parameter regression(considering effect of confining pressure,rock mass properties and fluid pressure) was performed on numerical results which resulted in an equation.The proposed equation considers the effect of confining pressure and its results are in good agreement with numerical results.
基金supported by the Open Foundation of State Key Laboratory of Hydrology-Water Resources (Grant No. 2012490211)the Doctoral Scientific Research Fund of Northwest A&F University in 2012 (Grant No.2012BSJJ007)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. QN2013046)the National Natural Science Foundation of China (Grant No. 51139001)
文摘The distinct characteristic of subcritical propagation requires at least two control parameters to completely express expansion of cracks in the concrete.The basic definition of crack tip opening displacement(CTOD)is corrected based on the monitored variable of crack mouth opening displacement(CMOD).The improved CTOD criterion,called the double CTODd criterion,for the abnormality diagnosis of cracks in the concrete is constructed based on the fictitious crack model and linear asymptotic superposition assumptions of the concrete.The double CTODd criterion is verified using two specimens of three-point bending notched beam.The verification results are reasonable and correct.The establishment of the double CTODd criterion lays a solid theoretical foundation for the abnormality diagnosis of cracks in concrete structures(such as concrete dams)based on CMOD.
