Water-coupled charge blasting is a promising technique to efficiently break rock masses.In this study,numerical models of double boreholes with water-coupled charge are established using LS-DYNA and are calibrated by ...Water-coupled charge blasting is a promising technique to efficiently break rock masses.In this study,numerical models of double boreholes with water-coupled charge are established using LS-DYNA and are calibrated by the tests of rock masses subjected to explosion loads to examine its performance.The crack levels of rock mass induced by water-coupled charge blasting and air-coupled charge blasting are first compared.It is found that water-coupled charge blasting is more appropriate to fracture deep rock mass than air-coupled charge blasting.In addition,the effects of rock properties,water-coupled charge coefficients,and borehole connection angles on the performance of water-coupled charge blasting are investigated.The results show that rock properties and water-coupled charge coefficients can greatly influence the crack and fragmentation levels of rock mass induced by water-coupled charge blasting under uniform and non-uniform in-situ stresses.However,changing borehole-connection angles can only affect crack and fragmentation levels of rock mass under non-uniform in-situ stresses but barely affect those under uniform in-situ stresses.A formula is finally proposed by considering the above-mentioned factors to provide the design suggestion of water-coupled charge blasting to fracture rock mass with different in-situ stresses.展开更多
In this article, we report the preparation of a three-dimensional(3D) interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional(2D) hexagonal mes...In this article, we report the preparation of a three-dimensional(3D) interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional(2D) hexagonal mesoporous anatase 70 TiO2-30 SiO2-950 nanocomposite(crystallized at 950 °C for 2 h) as a precursor, NaO H as an etchant of SiO2 via a "creating mesopores in the pore walls" approach. Our strategy adopts mild conditions of creating pores such as diluted NaO H solution, appropriate temperature and solid/liquid ratio, etc. aiming at ensuring the integrities of mesopores architecture and anatase nanocrystals. XRD, TEM and N2 sorption techniques have been used to systematically investigate the physico-chemical properties of the nanocomposites. The results show that the intrawall mesopores are highly dense and uniform(average pore size 3.6 nm), and highly link the initial mesochannels in a 3D manner while retaining mesostructural integrity. There is no significant change to either crystallinity or size of the anatase nanocrystals before and after creating the intrawall mesopores. The photocatalytic degradation rates of rhodamine B(RhB, 0.303 min^–1) and methylene blue(MB, 0.757 min^–1) dyes on the resultant nanocomposite are very high, which are 5.1 and 5.3 times that of the precursor; even up to 16.5 and 24.1 times that of Degussa P25 photocatalyst, respectively. These results clearly demonstrate that the 3D interconnected mesopores structure plays an overwhelming role to the increments of activities. The 3D mesoporous anatase TiO2-SiO2 nanocomposite exhibits unexpected-high degradation activities to RhB and MB in the mesoporous metal oxide-based materials reported so far. Additionally, the nanocomposite is considerably stable and reusable. We believe that this method would pave the way for the preparation of other 3D highly interconnected mesoporous metal oxide-based materials with ultra-high performance.展开更多
W-Ni 合金内连孔在固相烧结中的断裂J-W,Noh et al(Agency for Defence Devel-opment,Taejon,Korea)添加0.03—0.1%Ni 的 W 压坯经烧结后进行显微结构分析,结果表明孔断裂发生在三晶粒结合处而闭孔在四晶粒结合处形成。孔独立存在的临...W-Ni 合金内连孔在固相烧结中的断裂J-W,Noh et al(Agency for Defence Devel-opment,Taejon,Korea)添加0.03—0.1%Ni 的 W 压坯经烧结后进行显微结构分析,结果表明孔断裂发生在三晶粒结合处而闭孔在四晶粒结合处形成。孔独立存在的临界密度本文报道为形态扰动理论预测值的两倍。本文结论指出,晶界扩散和表面张力在闭孔形成中起着重要作用。展开更多
基金Projects(52334003,52104111,52274249)supported by the National Natural Science Foundation of ChinaProject(2022YFC2903901)supported by the National Key R&D Project of ChinaProject(2024JJ4064)supported by the Natural Science Foundation of Hunan Province,China。
文摘Water-coupled charge blasting is a promising technique to efficiently break rock masses.In this study,numerical models of double boreholes with water-coupled charge are established using LS-DYNA and are calibrated by the tests of rock masses subjected to explosion loads to examine its performance.The crack levels of rock mass induced by water-coupled charge blasting and air-coupled charge blasting are first compared.It is found that water-coupled charge blasting is more appropriate to fracture deep rock mass than air-coupled charge blasting.In addition,the effects of rock properties,water-coupled charge coefficients,and borehole connection angles on the performance of water-coupled charge blasting are investigated.The results show that rock properties and water-coupled charge coefficients can greatly influence the crack and fragmentation levels of rock mass induced by water-coupled charge blasting under uniform and non-uniform in-situ stresses.However,changing borehole-connection angles can only affect crack and fragmentation levels of rock mass under non-uniform in-situ stresses but barely affect those under uniform in-situ stresses.A formula is finally proposed by considering the above-mentioned factors to provide the design suggestion of water-coupled charge blasting to fracture rock mass with different in-situ stresses.
基金supported by the National Natural Science Foundation of China(21373056)the Science and Technology Commission of Shanghai Municipality(13DZ2275200)~~
文摘In this article, we report the preparation of a three-dimensional(3D) interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional(2D) hexagonal mesoporous anatase 70 TiO2-30 SiO2-950 nanocomposite(crystallized at 950 °C for 2 h) as a precursor, NaO H as an etchant of SiO2 via a "creating mesopores in the pore walls" approach. Our strategy adopts mild conditions of creating pores such as diluted NaO H solution, appropriate temperature and solid/liquid ratio, etc. aiming at ensuring the integrities of mesopores architecture and anatase nanocrystals. XRD, TEM and N2 sorption techniques have been used to systematically investigate the physico-chemical properties of the nanocomposites. The results show that the intrawall mesopores are highly dense and uniform(average pore size 3.6 nm), and highly link the initial mesochannels in a 3D manner while retaining mesostructural integrity. There is no significant change to either crystallinity or size of the anatase nanocrystals before and after creating the intrawall mesopores. The photocatalytic degradation rates of rhodamine B(RhB, 0.303 min^–1) and methylene blue(MB, 0.757 min^–1) dyes on the resultant nanocomposite are very high, which are 5.1 and 5.3 times that of the precursor; even up to 16.5 and 24.1 times that of Degussa P25 photocatalyst, respectively. These results clearly demonstrate that the 3D interconnected mesopores structure plays an overwhelming role to the increments of activities. The 3D mesoporous anatase TiO2-SiO2 nanocomposite exhibits unexpected-high degradation activities to RhB and MB in the mesoporous metal oxide-based materials reported so far. Additionally, the nanocomposite is considerably stable and reusable. We believe that this method would pave the way for the preparation of other 3D highly interconnected mesoporous metal oxide-based materials with ultra-high performance.
文摘W-Ni 合金内连孔在固相烧结中的断裂J-W,Noh et al(Agency for Defence Devel-opment,Taejon,Korea)添加0.03—0.1%Ni 的 W 压坯经烧结后进行显微结构分析,结果表明孔断裂发生在三晶粒结合处而闭孔在四晶粒结合处形成。孔独立存在的临界密度本文报道为形态扰动理论预测值的两倍。本文结论指出,晶界扩散和表面张力在闭孔形成中起着重要作用。