Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the...Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the deep-sea sediment collected from the Pacific C-C area. Shear creep characteristics of the simulative soil were studied by shear creep test and shear creep parameters were determined by Burgers creep model. Research results show that the shear creep curves of the simulative soil can be divided into transient creep, unstable creep and stable creep, where the unstable creep stage is very short due to its high water content. The shear creep parameters increase with compressive stress and change slightly or fluctuate to approach a constant value with shear stress, and thus average creep parameters under the same compressive stress are used as the creep parameters of the simulative soil. Traction of the deep-sea mining machine walking at a constant velocity can be calculated by the shear creep constitutive equation of the deep-sea simulative soil, which provides a theoretical basis for safe operation and optimal design of the deep-sea mining machine.展开更多
This study sought to forecast water flow and sediment flux in the scheme as potential contributions for improved management in the Chókwè Irrigation Scheme (CIS). Fieldwork data was collected during dry (DS)...This study sought to forecast water flow and sediment flux in the scheme as potential contributions for improved management in the Chókwè Irrigation Scheme (CIS). Fieldwork data was collected during dry (DS) and wet (WS) seasons. Flow measurement was performed at 9 stations using a calibrated flow meter OTT C31. Water flow and sediment flux from 2004 to 2019 were used. Hydrodynamic forecast simulations were performed using Mann-Kendall test and ARIMA model for determination of temporal trends. Findings suggest higher values during DS for water discharge and sediment flux. Mann-Kendall test for sediment discharge trends was not significant at 95% significance level, except for the Offtake in WS. ARIMA test for the sediment discharges, at the Intake, for DS and WS, sediments were well described by the ARIMA model and gave a good result for the sediments. Good fit between the observed and the predicted ARIMA model was found. ARIMA model for sediment discharge at CIS based on AIC has a good fit for AR (p = 1), whereby, at the Intake the ARIMA p-value was 0.822 and 0.932, for WS and DS, respectively. Whilst in the Offtake, the ARIMA p-value was 0.877 and 0.893, respectively. These results can be used to improve the CIS management, both for water flow and sediment flux.展开更多
基金Project(51274251)supported by the National Natural Science Foundation of China
文摘Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the deep-sea sediment collected from the Pacific C-C area. Shear creep characteristics of the simulative soil were studied by shear creep test and shear creep parameters were determined by Burgers creep model. Research results show that the shear creep curves of the simulative soil can be divided into transient creep, unstable creep and stable creep, where the unstable creep stage is very short due to its high water content. The shear creep parameters increase with compressive stress and change slightly or fluctuate to approach a constant value with shear stress, and thus average creep parameters under the same compressive stress are used as the creep parameters of the simulative soil. Traction of the deep-sea mining machine walking at a constant velocity can be calculated by the shear creep constitutive equation of the deep-sea simulative soil, which provides a theoretical basis for safe operation and optimal design of the deep-sea mining machine.
文摘This study sought to forecast water flow and sediment flux in the scheme as potential contributions for improved management in the Chókwè Irrigation Scheme (CIS). Fieldwork data was collected during dry (DS) and wet (WS) seasons. Flow measurement was performed at 9 stations using a calibrated flow meter OTT C31. Water flow and sediment flux from 2004 to 2019 were used. Hydrodynamic forecast simulations were performed using Mann-Kendall test and ARIMA model for determination of temporal trends. Findings suggest higher values during DS for water discharge and sediment flux. Mann-Kendall test for sediment discharge trends was not significant at 95% significance level, except for the Offtake in WS. ARIMA test for the sediment discharges, at the Intake, for DS and WS, sediments were well described by the ARIMA model and gave a good result for the sediments. Good fit between the observed and the predicted ARIMA model was found. ARIMA model for sediment discharge at CIS based on AIC has a good fit for AR (p = 1), whereby, at the Intake the ARIMA p-value was 0.822 and 0.932, for WS and DS, respectively. Whilst in the Offtake, the ARIMA p-value was 0.877 and 0.893, respectively. These results can be used to improve the CIS management, both for water flow and sediment flux.
