Deep in-situ rock mechanics considers the influence of the in-situ environment on mechanical properties,differentiating it from traditional rock mechanics.To investigate the effect of in-situ stress,pore pressure pres...Deep in-situ rock mechanics considers the influence of the in-situ environment on mechanical properties,differentiating it from traditional rock mechanics.To investigate the effect of in-situ stress,pore pressure preserved environment on the mechanical difference of sandstone,four tests are numerically modeled by COMSOL:conventional triaxial test,conventional pore pressure test,in-situ stress restoration and reconstruction test,and in-situ pore pressure-preserved test(not yet realized in the laboratory).The in-situ stress restoration parameter is introduced to characterize the recovery effect of in-situ stress on elastic modulus and heterogeneous distribution of sandstone at different depths.A random function and nonuniform pore pressure coefficient are employed to describe the non-uniform distribution of pore pressure in the in-situ environment.Numerical results are compared with existing experimental data to validate the models and calibrate the numerical parameters.By extracting mechanical parameters from numerical cores,the stress-strain curves of the four tests under different depths,in-situ stress and pore pressure are compared.The influence of non-uniform pore pressure coefficient and depth on the peak strength of sandstone is analyzed.The results show a strong linear relationship between the in-situ stress restoration parameter and depth,effectively characterizing the enhanced effect of stress restoration and reconstruction methods on the elastic modulus of conventional cores at different depths.The in-situ pore pressurepreserved test exhibits lower peak stress and peak strain compared to the other three tests,and sandstone subjected to non-uniform pore pressure is more prone to plastic damage and failure.Moreover,the influence of non-uniform pore pressure on peak strength gradually diminished with increasing depth.展开更多
There are close relationships between the sea surface temperature (SST) and the surface wind over the tropical Pacific.To study the past climate variability over the tropical Pacific,the long-term monthly wind stress ...There are close relationships between the sea surface temperature (SST) and the surface wind over the tropical Pacific.To study the past climate variability over the tropical Pacific,the long-term monthly wind stress anomalies over the tropical Pacific for the period of 1856–2008 are reconstructed with an SVD (singular value decomposition)-based statistical atmospheric model,where the wind stress anomalies are slave and directly correspond to the SST anomalies.The verification results show that the reconstructed wind stress data have high correlations and a small root mean square (RMS) error with the three reanalysis/simulated surface wind datasets from the last 50 years.In addition,the simulated SST anomalies from an intermediate oceanic model (IOM),which is forced by the reconstructed wind stress,can simulate the realistic interannual and decadal variability of the ENSO (El Nio-Southern Oscillation);this indicates that this new long-term wind stress dataset is useful for various climate studies,especially for the large-scale interannual and decadal variability.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51827901 and 52121003)the 111 Project(No.B14006)+1 种基金the Yueqi Outstanding Scholar Program of CUMTB(No.2017A03)the Fundamental Research Funds for the Central Universities(No.2022YJSNY13).
文摘Deep in-situ rock mechanics considers the influence of the in-situ environment on mechanical properties,differentiating it from traditional rock mechanics.To investigate the effect of in-situ stress,pore pressure preserved environment on the mechanical difference of sandstone,four tests are numerically modeled by COMSOL:conventional triaxial test,conventional pore pressure test,in-situ stress restoration and reconstruction test,and in-situ pore pressure-preserved test(not yet realized in the laboratory).The in-situ stress restoration parameter is introduced to characterize the recovery effect of in-situ stress on elastic modulus and heterogeneous distribution of sandstone at different depths.A random function and nonuniform pore pressure coefficient are employed to describe the non-uniform distribution of pore pressure in the in-situ environment.Numerical results are compared with existing experimental data to validate the models and calibrate the numerical parameters.By extracting mechanical parameters from numerical cores,the stress-strain curves of the four tests under different depths,in-situ stress and pore pressure are compared.The influence of non-uniform pore pressure coefficient and depth on the peak strength of sandstone is analyzed.The results show a strong linear relationship between the in-situ stress restoration parameter and depth,effectively characterizing the enhanced effect of stress restoration and reconstruction methods on the elastic modulus of conventional cores at different depths.The in-situ pore pressurepreserved test exhibits lower peak stress and peak strain compared to the other three tests,and sandstone subjected to non-uniform pore pressure is more prone to plastic damage and failure.Moreover,the influence of non-uniform pore pressure on peak strength gradually diminished with increasing depth.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant Nos.KZCX2-YW-202 and KZCX1-YW-12-03)the National Basic Research Program of China (Grant No.2006CB403600)+1 种基金the National Natural Sciences Foundation of China (Grant Nos.40805033 and 40221503)Chinese COPES project (GYHY-200706005)
文摘There are close relationships between the sea surface temperature (SST) and the surface wind over the tropical Pacific.To study the past climate variability over the tropical Pacific,the long-term monthly wind stress anomalies over the tropical Pacific for the period of 1856–2008 are reconstructed with an SVD (singular value decomposition)-based statistical atmospheric model,where the wind stress anomalies are slave and directly correspond to the SST anomalies.The verification results show that the reconstructed wind stress data have high correlations and a small root mean square (RMS) error with the three reanalysis/simulated surface wind datasets from the last 50 years.In addition,the simulated SST anomalies from an intermediate oceanic model (IOM),which is forced by the reconstructed wind stress,can simulate the realistic interannual and decadal variability of the ENSO (El Nio-Southern Oscillation);this indicates that this new long-term wind stress dataset is useful for various climate studies,especially for the large-scale interannual and decadal variability.