软岩在世界上分布非常广泛且其工程性质特殊,目前日益得到岩土工程工作者的关注。本文以长沙北辰A1地块项目为例,对软岩进行了工程实践研究。首先,通过调研勘察资料研判岩土参数指标,有针对性地制定了专项现场试验方案,即浅层平板载荷...软岩在世界上分布非常广泛且其工程性质特殊,目前日益得到岩土工程工作者的关注。本文以长沙北辰A1地块项目为例,对软岩进行了工程实践研究。首先,通过调研勘察资料研判岩土参数指标,有针对性地制定了专项现场试验方案,即浅层平板载荷试验和旁压试验,验证了工程特性指标,试验结果表明强风化泥质砂岩的天然地基承载力可以满足要求,同时测得了变形模量和旁压模量。然后在此基础上,运用数值软件Plaxis 3D Foundation进行了筏板基础天然地基方案的沉降计算,通过对计算结果的分析,判断总沉降量和差异沉降均满足《建筑地基基础设计规范》(GB 50007-2011)要求。最后通过对沉降实测资料的分析,发现沉降计算结果与沉降观测值两者变形趋势完全吻合,实测值略小于计算值。本工程采用现场平板载荷试验及旁压试验确定工程特性指标进而据此完成了地基基础设计,实践证明是科学合理、安全可靠的。本工程为目前长沙软岩场地已经建成的第一栋采用天然地基方案的超高楼,为今后该地区超高层建筑地基岩土工程评价与地基基础设计积累了经验。展开更多
It is important to study the effect of hydrate production on the physical and mechanical properties of low-permeability clayey–silty reservoirs for the largescale exploitation of hydrate reservoirs in the South China...It is important to study the effect of hydrate production on the physical and mechanical properties of low-permeability clayey–silty reservoirs for the largescale exploitation of hydrate reservoirs in the South China Sea.In this study,a multiphysical-field coupling model,combined with actual exploration drilling data and the mechanical experimental data of hydrate cores in the laboratory,was established to investigate the physical and mechanical properties of low-permeability reservoirs with different slope angles during 5-year hydrate production by the depressurization method via a horizontal well.The result shows that the permeability of reservoirs severely affects gas production rate,and the maximum gas production amount of a 20-m-long horizontal well can reach186.8 m3/day during the 5-year hydrate production.Reservoirs with smaller slope angles show higher gas production rates.The depressurization propagation and hydrate dissociation mainly develop along the direction parallel to the slope.Besides,the mean effective stress of reservoirs is concentrated in the near-wellbore area with the on-going hydrate production,and gradually decreases with the increase of the slope angle.Different from the effective stress distribution law,the total reservoir settlement amount first decreases and then increases with the increase of the slope angle.The maximum settlement of reservoirs with a 0°slope angle is up to 3.4 m,and the displacement in the near-wellbore area is as high as2.2 m after 5 years of hydrate production.It is concluded that the pore pressure drop region of low-permeability reservoirs in the South China Sea is limited,and various slope angles further lead to differences in effective stress and strain of reservoirs during hydrate production,resulting in severe uneven settlement of reservoirs.展开更多
With rapid environmental degeneration and socio-economie development,the human settlement environment (HSE)has experienced dramatic changes and attracted attention from different communities.Consequently,the spatial-t...With rapid environmental degeneration and socio-economie development,the human settlement environment (HSE)has experienced dramatic changes and attracted attention from different communities.Consequently,the spatial-temporal evaluation of natural suitability of the human settlement environment (NSHSE)has become essential for understanding the patterns and dynamics of HSE,and for coordinating sustainable development among regional populations,resources,and environments.This study aims to explore the spatialtemporal evolution of NSHSE patterns in 1997,2005,and 2009 in Fengjie County near the Three Gorges Reservoir Area (TGRA).A spatially weighted NSHSE model was established by integrating multi-source data (e.g.,census data,meteorological data,remote sensing images,DEM data,and GIS data)into one framework,where the Ordinary Least Squares (OLS)linear regression model was applied to calculate the weights of indices in the NSHSE model.Results show that the trend of natural suitability has been first downward and then upward, which is evidenced by the disparity of NSHSE existing in the south,north,and central areas of Fengjie County. Results also reveal clustered NSHSE patterns for all 30 townships.Meanwhile,NSHSE has significant influence on population distribution,and 71.49% of the total population is living in moderate and high suitable districts.展开更多
抛光渣是抛光粉在使用过程中因混入杂质而失去使用价值的废弃物,传统的丢弃或掩埋处理不仅造成资源的浪费,而且造成环境污染。本研究以某低品位铈基稀土抛光渣(CeO_2含量为0.88%)为试样,采用初步沉降预富集,硫酸+双氧水浸出,氨水、Na2S...抛光渣是抛光粉在使用过程中因混入杂质而失去使用价值的废弃物,传统的丢弃或掩埋处理不仅造成资源的浪费,而且造成环境污染。本研究以某低品位铈基稀土抛光渣(CeO_2含量为0.88%)为试样,采用初步沉降预富集,硫酸+双氧水浸出,氨水、Na2S相继除杂,草酸沉淀,沉淀产物高温煅烧工艺进行了CeO_2回收试验。结果表明:(1)废弃抛光渣在pH=9的情况下沉降8 h,可得到CeO_2品位为1.70%、回收率为84.62%的预富集产物。(2)预富集产物在硫酸浓度为0.5 mol/L,用量为100 m L,双氧水用量15 m L,反应温度为80℃情况下水浴加热、搅拌、浸出3.5 h,稀土浸出率可达94.70%。(3)用氨水、Na2S对浸出液进行了除杂处理,Al^(3+)、Fe^(3+)、Pb^(2+)、Zn^(2+)的去除率分别为94.03%、76.67%、99.89%、99.94%,然后用草酸沉淀稀土,稀土沉淀率为91.82%。(4)稀土草酸盐沉淀产物高温煅烧得到CeO_2含量为93.48%的晶体,纯度较高,扫描电镜观察表明,该CeO_2晶体多呈块状。展开更多
文摘软岩在世界上分布非常广泛且其工程性质特殊,目前日益得到岩土工程工作者的关注。本文以长沙北辰A1地块项目为例,对软岩进行了工程实践研究。首先,通过调研勘察资料研判岩土参数指标,有针对性地制定了专项现场试验方案,即浅层平板载荷试验和旁压试验,验证了工程特性指标,试验结果表明强风化泥质砂岩的天然地基承载力可以满足要求,同时测得了变形模量和旁压模量。然后在此基础上,运用数值软件Plaxis 3D Foundation进行了筏板基础天然地基方案的沉降计算,通过对计算结果的分析,判断总沉降量和差异沉降均满足《建筑地基基础设计规范》(GB 50007-2011)要求。最后通过对沉降实测资料的分析,发现沉降计算结果与沉降观测值两者变形趋势完全吻合,实测值略小于计算值。本工程采用现场平板载荷试验及旁压试验确定工程特性指标进而据此完成了地基基础设计,实践证明是科学合理、安全可靠的。本工程为目前长沙软岩场地已经建成的第一栋采用天然地基方案的超高楼,为今后该地区超高层建筑地基岩土工程评价与地基基础设计积累了经验。
基金China Postdoctoral Science Foundation,Grant/Award Number:2020M681768Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20200653+1 种基金Fundamental Research Funds for the Central Universities,Grant/Award Number:2021GJZPY15National Natural Science Foundation of China,Grant/Award Number:42106210。
文摘It is important to study the effect of hydrate production on the physical and mechanical properties of low-permeability clayey–silty reservoirs for the largescale exploitation of hydrate reservoirs in the South China Sea.In this study,a multiphysical-field coupling model,combined with actual exploration drilling data and the mechanical experimental data of hydrate cores in the laboratory,was established to investigate the physical and mechanical properties of low-permeability reservoirs with different slope angles during 5-year hydrate production by the depressurization method via a horizontal well.The result shows that the permeability of reservoirs severely affects gas production rate,and the maximum gas production amount of a 20-m-long horizontal well can reach186.8 m3/day during the 5-year hydrate production.Reservoirs with smaller slope angles show higher gas production rates.The depressurization propagation and hydrate dissociation mainly develop along the direction parallel to the slope.Besides,the mean effective stress of reservoirs is concentrated in the near-wellbore area with the on-going hydrate production,and gradually decreases with the increase of the slope angle.Different from the effective stress distribution law,the total reservoir settlement amount first decreases and then increases with the increase of the slope angle.The maximum settlement of reservoirs with a 0°slope angle is up to 3.4 m,and the displacement in the near-wellbore area is as high as2.2 m after 5 years of hydrate production.It is concluded that the pore pressure drop region of low-permeability reservoirs in the South China Sea is limited,and various slope angles further lead to differences in effective stress and strain of reservoirs during hydrate production,resulting in severe uneven settlement of reservoirs.
文摘With rapid environmental degeneration and socio-economie development,the human settlement environment (HSE)has experienced dramatic changes and attracted attention from different communities.Consequently,the spatial-temporal evaluation of natural suitability of the human settlement environment (NSHSE)has become essential for understanding the patterns and dynamics of HSE,and for coordinating sustainable development among regional populations,resources,and environments.This study aims to explore the spatialtemporal evolution of NSHSE patterns in 1997,2005,and 2009 in Fengjie County near the Three Gorges Reservoir Area (TGRA).A spatially weighted NSHSE model was established by integrating multi-source data (e.g.,census data,meteorological data,remote sensing images,DEM data,and GIS data)into one framework,where the Ordinary Least Squares (OLS)linear regression model was applied to calculate the weights of indices in the NSHSE model.Results show that the trend of natural suitability has been first downward and then upward, which is evidenced by the disparity of NSHSE existing in the south,north,and central areas of Fengjie County. Results also reveal clustered NSHSE patterns for all 30 townships.Meanwhile,NSHSE has significant influence on population distribution,and 71.49% of the total population is living in moderate and high suitable districts.
文摘抛光渣是抛光粉在使用过程中因混入杂质而失去使用价值的废弃物,传统的丢弃或掩埋处理不仅造成资源的浪费,而且造成环境污染。本研究以某低品位铈基稀土抛光渣(CeO_2含量为0.88%)为试样,采用初步沉降预富集,硫酸+双氧水浸出,氨水、Na2S相继除杂,草酸沉淀,沉淀产物高温煅烧工艺进行了CeO_2回收试验。结果表明:(1)废弃抛光渣在pH=9的情况下沉降8 h,可得到CeO_2品位为1.70%、回收率为84.62%的预富集产物。(2)预富集产物在硫酸浓度为0.5 mol/L,用量为100 m L,双氧水用量15 m L,反应温度为80℃情况下水浴加热、搅拌、浸出3.5 h,稀土浸出率可达94.70%。(3)用氨水、Na2S对浸出液进行了除杂处理,Al^(3+)、Fe^(3+)、Pb^(2+)、Zn^(2+)的去除率分别为94.03%、76.67%、99.89%、99.94%,然后用草酸沉淀稀土,稀土沉淀率为91.82%。(4)稀土草酸盐沉淀产物高温煅烧得到CeO_2含量为93.48%的晶体,纯度较高,扫描电镜观察表明,该CeO_2晶体多呈块状。
