脑小血管病(cerebral small vessel disease,CSVD)是临床上常见的一类与年龄相关的脑血管疾病。脑白质高信号(whitematterhypertensities,WMH)是CSVD的影像标志物之一。WMH患病率极高,与认知障碍的发生发展密切相关,但其影像表现及临床...脑小血管病(cerebral small vessel disease,CSVD)是临床上常见的一类与年龄相关的脑血管疾病。脑白质高信号(whitematterhypertensities,WMH)是CSVD的影像标志物之一。WMH患病率极高,与认知障碍的发生发展密切相关,但其影像表现及临床症状的异质性为早期发现、早期诊断带来了困难。本文从病理学、影像学及生物学3方面对WMH发生发展及其导致认知障碍的机制研究现况进行综述,同时总结目前的治疗策略,提出了接下来的研究目标及方向:能够反映预后的标志物及预测模型的研究,WMH发生发展的病理生理学机制研究,针对早期干预、药物开发的潜在靶点的研究等。展开更多
Rockbursts were frequently encountered in the construction of deeply buried tunnels at the Jinping-II hydropower station, Southwest China. In those cases, the existence of large structural planes, such as faults, was ...Rockbursts were frequently encountered in the construction of deeply buried tunnels at the Jinping-II hydropower station, Southwest China. In those cases, the existence of large structural planes, such as faults, was usually observed near the excavation boundaries. The formation mechanism of the “11·28” rockburst, which was a typical rockburst and occurred in a drainage tunnel under a deep burial depth, high in-situ stress state and complex geological conditions, has been difficult to explain. Realistic failure process analysis(RFPA3D) software was adopted to numerically simulate the whole failure process of the surrounding rock mass around the tunnel subjected to excavation. The spatial distribution of acoustic emission derived from numerical simulation contributed to explaining the mechanical responses of the process. Analyses of the stress, safety reserve coefficient and damage degree were performed to reveal the effect of faults on the formation of rockbursts in the deep tunnel. The existence of faults results in the formation of stress anomaly areas between the tunnel and the fault. The surrounding rock mass failure propagates toward the fault from the initial failure, to different degrees. The relative positions and angles of faults play significant roles in the extent and development of surrounding rock mass failure, respectively. The increase in the lateral stress coefficient leads to the aggravation of the surrounding rock mass damage, especially in the roof and floor of the tunnel. Moreover, as the rock strength-stress ratio increases, the failure mode of the near-fault tunnel gradually changes from the stress-controlled type to the compound-controlled type. These findings were consistent with the microseismic monitoring results and field observations, which was helpful to understand the mechanical behavior of tunnel excavation affected by faults. The achievements of this study can provide some references for analysis of the failure mechanisms of similar deep tunnels.展开更多
文摘脑小血管病(cerebral small vessel disease,CSVD)是临床上常见的一类与年龄相关的脑血管疾病。脑白质高信号(whitematterhypertensities,WMH)是CSVD的影像标志物之一。WMH患病率极高,与认知障碍的发生发展密切相关,但其影像表现及临床症状的异质性为早期发现、早期诊断带来了困难。本文从病理学、影像学及生物学3方面对WMH发生发展及其导致认知障碍的机制研究现况进行综述,同时总结目前的治疗策略,提出了接下来的研究目标及方向:能够反映预后的标志物及预测模型的研究,WMH发生发展的病理生理学机制研究,针对早期干预、药物开发的潜在靶点的研究等。
基金Project(42177143) supported by the National Natural Science Foundation of ChinaProject(2020JDJQ0011) supported by the Science Foundation for Distinguished Young Scholars of Sichuan Province,China。
文摘Rockbursts were frequently encountered in the construction of deeply buried tunnels at the Jinping-II hydropower station, Southwest China. In those cases, the existence of large structural planes, such as faults, was usually observed near the excavation boundaries. The formation mechanism of the “11·28” rockburst, which was a typical rockburst and occurred in a drainage tunnel under a deep burial depth, high in-situ stress state and complex geological conditions, has been difficult to explain. Realistic failure process analysis(RFPA3D) software was adopted to numerically simulate the whole failure process of the surrounding rock mass around the tunnel subjected to excavation. The spatial distribution of acoustic emission derived from numerical simulation contributed to explaining the mechanical responses of the process. Analyses of the stress, safety reserve coefficient and damage degree were performed to reveal the effect of faults on the formation of rockbursts in the deep tunnel. The existence of faults results in the formation of stress anomaly areas between the tunnel and the fault. The surrounding rock mass failure propagates toward the fault from the initial failure, to different degrees. The relative positions and angles of faults play significant roles in the extent and development of surrounding rock mass failure, respectively. The increase in the lateral stress coefficient leads to the aggravation of the surrounding rock mass damage, especially in the roof and floor of the tunnel. Moreover, as the rock strength-stress ratio increases, the failure mode of the near-fault tunnel gradually changes from the stress-controlled type to the compound-controlled type. These findings were consistent with the microseismic monitoring results and field observations, which was helpful to understand the mechanical behavior of tunnel excavation affected by faults. The achievements of this study can provide some references for analysis of the failure mechanisms of similar deep tunnels.
