The tectonic stress patterns were determined by a fuzzy comprehensive assessment method. Data of in-situ survey and fault information were utilized in the method. First, by making pressure and tension in the direction...The tectonic stress patterns were determined by a fuzzy comprehensive assessment method. Data of in-situ survey and fault information were utilized in the method. First, by making pressure and tension in the directions of along-river, cross-river, shear clockwise, and shear counterclockwise , 26 types of tectonic stress patterns were presented. And the stress vector of each pattern was obtained with FE software by taking unit displacement as boundary load. Then, by taking the 26 types of tectonic stress patterns as index set and 3 main stresses as factor set and choosing various operators, comparison of directions of computational stress vector and survey stress vector was made and the most possible tectonic stress pattern was obtained. Taking the 26 types of tectonic stress patterns as index set and strike angle as factor set, comparison of relationships between formation of fault and tectonic stress was made,and the tectonic stress patterns were assessed with known fault information. By summarizing the above assessment results, the most impossible tectonic stress pattern was obtained . Finally an engineering case was quoted to validate that the method is more feasible and reliable than traditional empirical method.展开更多
A new method, which is based on formation fracturing test and Kaiser effect method, has been developed for confirming the oilfield in-situ stress in this paper. The new method has been used in a certain oilfield of Ch...A new method, which is based on formation fracturing test and Kaiser effect method, has been developed for confirming the oilfield in-situ stress in this paper. The new method has been used in a certain oilfield of China and the determined oilfield in-situ stresses is more accurate than that based on one single method.展开更多
As mining delves deeper into the crust, it is necessary to investigate the complex rock responses associated with higher stress gradients. Therefore, it is essential to better understand the mechanisms associated with...As mining delves deeper into the crust, it is necessary to investigate the complex rock responses associated with higher stress gradients. Therefore, it is essential to better understand the mechanisms associated with the rockburst phenomenon. However, due to the large-scale and difficult monitoring of real mining excavations, laboratory scale tests must be utilised to determine the conditions conducive to burst. To this end, this research focuses on the implementation of a new rockburst testing apparatus to replicate the stress conditions of a rock mass excavation at the time of bursting. This apparatus allows the determination of rockburst stresses and a relationship between deviatoric stress and in-situ pressure/depth. Using this relationship it is then possible to estimate the standardised stress levels for a certain rock type which might lead to rockburst occurrence. Furthermore, it is demonstrated that with increasing in-situ pressure, the likelihood(measured as a lower differential stress) and the extent(indicated by the increasing range of deviatoric stress) of rockburst increases. These findings provide valuable information about the conditions necessary for bursting in deep mining.展开更多
The deformation behavior ofβ-quenched nearβTi-5321(Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe)alloy was systematically studied using in-situ tensile test monitored by the scanning electron microscopy(SEM).Besides,the electron ba...The deformation behavior ofβ-quenched nearβTi-5321(Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe)alloy was systematically studied using in-situ tensile test monitored by the scanning electron microscopy(SEM).Besides,the electron backscatter diffraction(EBSD)was performed to thoroughly discuss the deformation mechanisms.The results indicated that slip activities,crystal rotation and stress induced martensite transformation were the major deformation mechanisms in theβ-quenched Ti-5321 alloy during in-situ tensile testing.The slip activities were investigated by using the EBSD-trace analysis,which demonstrated that{110}<111>,{112}<111>and{123}<111>slip systems were activated and the{110}<111>slip system dominated.Besides,βgrains rotated about 7.8°to accommodate the increased macrostrain.Notably,the stress induced martensiteα″which was related to the double yielding behavior during tensile process exhibited multiple characteristics.The differentα″variants divided theβmatrix into smallerβblocks with a typical zigzag morphology,in which oneα″variant passed through another one by deflecting its initial growth direction.Moreover,the deformation twinning in martensiteα″and slip bands cutting through martensiteα″effectively accommodated the local strain.These systematically analysis can provide insightful information about the deformation mechanisms in nearβtitanium alloys.展开更多
文摘The tectonic stress patterns were determined by a fuzzy comprehensive assessment method. Data of in-situ survey and fault information were utilized in the method. First, by making pressure and tension in the directions of along-river, cross-river, shear clockwise, and shear counterclockwise , 26 types of tectonic stress patterns were presented. And the stress vector of each pattern was obtained with FE software by taking unit displacement as boundary load. Then, by taking the 26 types of tectonic stress patterns as index set and 3 main stresses as factor set and choosing various operators, comparison of directions of computational stress vector and survey stress vector was made and the most possible tectonic stress pattern was obtained. Taking the 26 types of tectonic stress patterns as index set and strike angle as factor set, comparison of relationships between formation of fault and tectonic stress was made,and the tectonic stress patterns were assessed with known fault information. By summarizing the above assessment results, the most impossible tectonic stress pattern was obtained . Finally an engineering case was quoted to validate that the method is more feasible and reliable than traditional empirical method.
文摘A new method, which is based on formation fracturing test and Kaiser effect method, has been developed for confirming the oilfield in-situ stress in this paper. The new method has been used in a certain oilfield of China and the determined oilfield in-situ stresses is more accurate than that based on one single method.
基金the Australian Research Council (No.LP150100539)
文摘As mining delves deeper into the crust, it is necessary to investigate the complex rock responses associated with higher stress gradients. Therefore, it is essential to better understand the mechanisms associated with the rockburst phenomenon. However, due to the large-scale and difficult monitoring of real mining excavations, laboratory scale tests must be utilised to determine the conditions conducive to burst. To this end, this research focuses on the implementation of a new rockburst testing apparatus to replicate the stress conditions of a rock mass excavation at the time of bursting. This apparatus allows the determination of rockburst stresses and a relationship between deviatoric stress and in-situ pressure/depth. Using this relationship it is then possible to estimate the standardised stress levels for a certain rock type which might lead to rockburst occurrence. Furthermore, it is demonstrated that with increasing in-situ pressure, the likelihood(measured as a lower differential stress) and the extent(indicated by the increasing range of deviatoric stress) of rockburst increases. These findings provide valuable information about the conditions necessary for bursting in deep mining.
基金financially supported by the National International Science and Technology Cooperation Project of China(No.2015DF151430)。
文摘The deformation behavior ofβ-quenched nearβTi-5321(Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe)alloy was systematically studied using in-situ tensile test monitored by the scanning electron microscopy(SEM).Besides,the electron backscatter diffraction(EBSD)was performed to thoroughly discuss the deformation mechanisms.The results indicated that slip activities,crystal rotation and stress induced martensite transformation were the major deformation mechanisms in theβ-quenched Ti-5321 alloy during in-situ tensile testing.The slip activities were investigated by using the EBSD-trace analysis,which demonstrated that{110}<111>,{112}<111>and{123}<111>slip systems were activated and the{110}<111>slip system dominated.Besides,βgrains rotated about 7.8°to accommodate the increased macrostrain.Notably,the stress induced martensiteα″which was related to the double yielding behavior during tensile process exhibited multiple characteristics.The differentα″variants divided theβmatrix into smallerβblocks with a typical zigzag morphology,in which oneα″variant passed through another one by deflecting its initial growth direction.Moreover,the deformation twinning in martensiteα″and slip bands cutting through martensiteα″effectively accommodated the local strain.These systematically analysis can provide insightful information about the deformation mechanisms in nearβtitanium alloys.
