The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loadi...The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loading and unloading stress path is designed and proposed.Subsequently,six brittleness indices are selected.In addition,the evolution characteristics of the six brittleness indices selected are characterized based on the bedding effect and the effect of confining pressure.Then,the entropy weight method(EWM)is introduced to assign weight to the six brittleness indices,and the comprehensive brittleness index Bcis defined and evaluated.Next,the new brittleness classification standard is determined,and the brittleness differences between the two stress paths are quantified.Finally,compared with the previous evaluation methods,the rationality of the proposed comprehensive brittleness index Bcis also verified.These results indicate that the proposed brittleness index Bccan reflect the brittle characteristics of deep bedded sandstone from the perspective of the whole life-cycle evolution process.Accordingly,the method proposed seems to offer reliable evaluations of the brittleness of deep bedded sandstone in deep engineering practices,although further validation is necessary.展开更多
Studies show that the dynamic properties of rockfill are strongly dependent on the confining pressure.Therefore,confining pressure effect has become a very important factor in the seismic analysis of high rockfill dam...Studies show that the dynamic properties of rockfill are strongly dependent on the confining pressure.Therefore,confining pressure effect has become a very important factor in the seismic analysis of high rockfill dam.The relationships of dynamic shear modulus versus dynamic shear strain and damping ratio versus dynamic shear strain had been improved to a certain degree on the basic of widely used Hardin-Drnevich constitutive model in this paper.Then a new model that could consider confining pressure effect has been established.Regression analysis was carried out of the dynamic triaxial experimental data of the damming materials in the Changheba hydropower station of Sichun Province,China.The results show that,the new model can fit the test data well under various confining pressures.A corresponding computational procedure was compiled and applied in the dynamic response analysis of the Changheba Dam.Comparing the calculation results between the new constitutive model and the ordinary Hardin-Drnevich model,it can be seen that the result is conservative to some extent without considering confining pressure effect.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52034009 and 51974319)the Yue Qi Distinguished Scholar Project(No.2020JCB01)。
文摘The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loading and unloading stress path is designed and proposed.Subsequently,six brittleness indices are selected.In addition,the evolution characteristics of the six brittleness indices selected are characterized based on the bedding effect and the effect of confining pressure.Then,the entropy weight method(EWM)is introduced to assign weight to the six brittleness indices,and the comprehensive brittleness index Bcis defined and evaluated.Next,the new brittleness classification standard is determined,and the brittleness differences between the two stress paths are quantified.Finally,compared with the previous evaluation methods,the rationality of the proposed comprehensive brittleness index Bcis also verified.These results indicate that the proposed brittleness index Bccan reflect the brittle characteristics of deep bedded sandstone from the perspective of the whole life-cycle evolution process.Accordingly,the method proposed seems to offer reliable evaluations of the brittleness of deep bedded sandstone in deep engineering practices,although further validation is necessary.
文摘Studies show that the dynamic properties of rockfill are strongly dependent on the confining pressure.Therefore,confining pressure effect has become a very important factor in the seismic analysis of high rockfill dam.The relationships of dynamic shear modulus versus dynamic shear strain and damping ratio versus dynamic shear strain had been improved to a certain degree on the basic of widely used Hardin-Drnevich constitutive model in this paper.Then a new model that could consider confining pressure effect has been established.Regression analysis was carried out of the dynamic triaxial experimental data of the damming materials in the Changheba hydropower station of Sichun Province,China.The results show that,the new model can fit the test data well under various confining pressures.A corresponding computational procedure was compiled and applied in the dynamic response analysis of the Changheba Dam.Comparing the calculation results between the new constitutive model and the ordinary Hardin-Drnevich model,it can be seen that the result is conservative to some extent without considering confining pressure effect.