三峡库区周期性水位升降引起的消落带岩体劣化对典型危岩岸坡稳定性具有重大影响。基于野外调研及地勘资料,采用通用离散单元法程序(universal distinct element code,简称UDEC)研究了消落带劣化区形态对近水平层状高陡危岩岸坡的稳定...三峡库区周期性水位升降引起的消落带岩体劣化对典型危岩岸坡稳定性具有重大影响。基于野外调研及地勘资料,采用通用离散单元法程序(universal distinct element code,简称UDEC)研究了消落带劣化区形态对近水平层状高陡危岩岸坡的稳定性影响。研究表明:目前三峡库区巫山段的近水平层状危岩岸坡消落带岩体劣化严重,在不同消落带劣化区存在紧密层状、松散碎裂状、溶蚀凹腔状、含挤压碎裂带等典型消落带劣化区形态;含有第1种消落带劣化区形态的危岩岸坡稳定性较好,危岩体位移较小,失稳模式为滑移破坏;含有第2种消落带劣化区形态的危岩岸坡危岩体先向坡内偏移,其后随着消落带岩体支撑强度弱化向坡外倾倒破坏;含有第3种消落带劣化区形态的危岩岸坡危岩体向坡外位移较大,失稳模式为倾倒破坏;含有第4种消落带劣化区形态的危岩岸坡稳定性主要受挤压破碎带的力学性质控制,易产生沿破碎带切割面的旋转滑移破坏;通过对以上4种劣化区形态的危岩岸坡增加防治加固措施,危岩体的变形位移得到了不同程度的有效控制。展开更多
目的建立适用于抹茶品质的可见近红外(visible-nearinfrared,Vis-NIR)光谱快速无损检测模型以实现多种品质指标的定量分析。方法通过Vis-NIR获取抹茶样本的光谱数据,使用一阶导数(first derivative,1^(st))光谱预处理方法,最后采用自助...目的建立适用于抹茶品质的可见近红外(visible-nearinfrared,Vis-NIR)光谱快速无损检测模型以实现多种品质指标的定量分析。方法通过Vis-NIR获取抹茶样本的光谱数据,使用一阶导数(first derivative,1^(st))光谱预处理方法,最后采用自助软收缩法(bootstrapping soft shrinkage,BOSS)、迭代变量子集优化法(iterative variable subset optimization,IVSO)和竞争性自适应重加权采样法(competitive adaptive reweighted sampling,CARS)筛选光谱特征变量,构建抹茶品质指标的偏最小二乘(partial least square,PLS)预测模型,探究光谱信息与茶多酚、游离氨基酸、酚氨比、咖啡碱和可溶性糖之间的定量关系。结果构建的Vis-NIR的CARS-PLS预测模型在抹茶品质指标含量预测方面均获得了最佳结果,预测相关系数(correlation coefficient in the prediction set,Rp)分别为0.9227、0.8906、0.9243、0.9381和0.9522;预测均方根误差(root mean square error in the prediction set,RMSEP)分别为0.867、0.337、0.557、0.216和0.440。结论本研究采用的Vis-NIR光谱技术综合了可见光、短波近红外和长波近红外的优势,在快速无损预测多种抹茶品质指标方面具有良好应用潜力,为抹茶品质的快速无损高效检测提供理论依据和技术支撑。展开更多
Tunnel-type anchorages(TTAs)installed in human gathering areas are characterized by a shallow burial depth,and in many instances,they utilize soft rock as the bearing stratum.However,the stability control measures and...Tunnel-type anchorages(TTAs)installed in human gathering areas are characterized by a shallow burial depth,and in many instances,they utilize soft rock as the bearing stratum.However,the stability control measures and the principle of shallow TTAs in soft rock have not been fully studied.Hence,a structure suitable for improving the stability of shallow TTAs in soft rock strata,named the anti-pull tie(APT),was added to the floor of the back face.Physical tests and numerical models were established to study the influence of the APT on the load transfer of TTAs,the mechanical response of the surrounding rock,the stress distribution of the interface,and the failure model.The mechanical characteristics of APTs were also studied.The results show that the ultimate bearing capacity of TTAs with an APT is increased by approximately 11.8%,as compared to the TTAs without an APT.Also,the bearing capacity of TTAs increases approximately linearly with increasing height,width,length,and quantity of APTs,and decreases approximately linearly with increasing distance from the back face and slope angle of the tie slope.The normal squeezing between the tie slope and the surrounding rock increases the shear resistance of the interface and expands the range of the surrounding rock participating in bearing sharing.Both tension and compression zones exist in the APT during loading.The tension zone extends from the tie toe to the tie bottom along the tie slope.The range of the tie body tension zone constantly expands to the deep part of the APT with an increasing load.The peak tensile stress value is located at the tie toe.The distribution of compressive stress in the tie body is the largest at the tie top,followed by the tie slope,and then the tie bottom.展开更多
文摘三峡库区周期性水位升降引起的消落带岩体劣化对典型危岩岸坡稳定性具有重大影响。基于野外调研及地勘资料,采用通用离散单元法程序(universal distinct element code,简称UDEC)研究了消落带劣化区形态对近水平层状高陡危岩岸坡的稳定性影响。研究表明:目前三峡库区巫山段的近水平层状危岩岸坡消落带岩体劣化严重,在不同消落带劣化区存在紧密层状、松散碎裂状、溶蚀凹腔状、含挤压碎裂带等典型消落带劣化区形态;含有第1种消落带劣化区形态的危岩岸坡稳定性较好,危岩体位移较小,失稳模式为滑移破坏;含有第2种消落带劣化区形态的危岩岸坡危岩体先向坡内偏移,其后随着消落带岩体支撑强度弱化向坡外倾倒破坏;含有第3种消落带劣化区形态的危岩岸坡危岩体向坡外位移较大,失稳模式为倾倒破坏;含有第4种消落带劣化区形态的危岩岸坡稳定性主要受挤压破碎带的力学性质控制,易产生沿破碎带切割面的旋转滑移破坏;通过对以上4种劣化区形态的危岩岸坡增加防治加固措施,危岩体的变形位移得到了不同程度的有效控制。
文摘目的建立适用于抹茶品质的可见近红外(visible-nearinfrared,Vis-NIR)光谱快速无损检测模型以实现多种品质指标的定量分析。方法通过Vis-NIR获取抹茶样本的光谱数据,使用一阶导数(first derivative,1^(st))光谱预处理方法,最后采用自助软收缩法(bootstrapping soft shrinkage,BOSS)、迭代变量子集优化法(iterative variable subset optimization,IVSO)和竞争性自适应重加权采样法(competitive adaptive reweighted sampling,CARS)筛选光谱特征变量,构建抹茶品质指标的偏最小二乘(partial least square,PLS)预测模型,探究光谱信息与茶多酚、游离氨基酸、酚氨比、咖啡碱和可溶性糖之间的定量关系。结果构建的Vis-NIR的CARS-PLS预测模型在抹茶品质指标含量预测方面均获得了最佳结果,预测相关系数(correlation coefficient in the prediction set,Rp)分别为0.9227、0.8906、0.9243、0.9381和0.9522;预测均方根误差(root mean square error in the prediction set,RMSEP)分别为0.867、0.337、0.557、0.216和0.440。结论本研究采用的Vis-NIR光谱技术综合了可见光、短波近红外和长波近红外的优势,在快速无损预测多种抹茶品质指标方面具有良好应用潜力,为抹茶品质的快速无损高效检测提供理论依据和技术支撑。
基金the financial support provided by the National Natural Science Foundation of China(Grant No.42302332)the Special Funding of Chongqing Postdoctoral Research Project(Grant No.2022CQBSHTB2061,2022CQBSHTB1010)+3 种基金the Chongqing Postdoctoral Science Foundation(Grant No.CSTB2022NSCQ-BHX0738,CSTB2023NSCQBHX0223)the China Postdoctoral Science Foundation(Grant No.2023M730432)the Natural Science Foundation of Chongqing(Grant No.CSTB2023NSCQMSX0913,cstc2021jcyj-msxm X0869)the Postdoctoral Science Foundation of Chongqing Jiaotong University(Grant No.F1220105,22JDKJC-A008)。
文摘Tunnel-type anchorages(TTAs)installed in human gathering areas are characterized by a shallow burial depth,and in many instances,they utilize soft rock as the bearing stratum.However,the stability control measures and the principle of shallow TTAs in soft rock have not been fully studied.Hence,a structure suitable for improving the stability of shallow TTAs in soft rock strata,named the anti-pull tie(APT),was added to the floor of the back face.Physical tests and numerical models were established to study the influence of the APT on the load transfer of TTAs,the mechanical response of the surrounding rock,the stress distribution of the interface,and the failure model.The mechanical characteristics of APTs were also studied.The results show that the ultimate bearing capacity of TTAs with an APT is increased by approximately 11.8%,as compared to the TTAs without an APT.Also,the bearing capacity of TTAs increases approximately linearly with increasing height,width,length,and quantity of APTs,and decreases approximately linearly with increasing distance from the back face and slope angle of the tie slope.The normal squeezing between the tie slope and the surrounding rock increases the shear resistance of the interface and expands the range of the surrounding rock participating in bearing sharing.Both tension and compression zones exist in the APT during loading.The tension zone extends from the tie toe to the tie bottom along the tie slope.The range of the tie body tension zone constantly expands to the deep part of the APT with an increasing load.The peak tensile stress value is located at the tie toe.The distribution of compressive stress in the tie body is the largest at the tie top,followed by the tie slope,and then the tie bottom.
