The control of large deformation problems in layered soft rock tunnels needs to solve urgently.The roof problem is particularly severe among the deformation issues in tunnels.This study first analyzes the asymmetric d...The control of large deformation problems in layered soft rock tunnels needs to solve urgently.The roof problem is particularly severe among the deformation issues in tunnels.This study first analyzes the asymmetric deformation modes in layered soft rock tunnels with large deformations.Subsequently,we construct a mechanical model under ideal conditions for controlling the roof of layered soft rock tunnels through high preload with the support of NPR anchor cables.The prominent roles of long and short NPR anchor cables in the support system are also analyzed.The results indicate the significance of high preload in controlling the roof of layered soft rock tunnels.The short NPR anchor cables effectively improve the integrity of the stratified soft rock layers,while the long NPR anchor cables effectively mobilize the self-bearing capacity of deep-stable rock layers.Finally,the high-preload support method with NPR anchor cables is validated to have a good effect on controlling large deformations in layered soft rock tunnels through field monitoring data.展开更多
Objective To observe the value of cranial ultrasound for perioperative patients with acute severe traumatic brain injury(sTBI).Methods Data of 55 sTBI patients who underwent craniotomy were retrospectively analyzed.Th...Objective To observe the value of cranial ultrasound for perioperative patients with acute severe traumatic brain injury(sTBI).Methods Data of 55 sTBI patients who underwent craniotomy were retrospectively analyzed.The patients were divided into observation group(n=15)and control group(n=40)according to received perioperative cranial ultrasound or not.The general data and surgical data were compared between groups,and ultrasonic data of observation group were analyzed.Results The proportions of good prognosis 1 and 6 months after operation in observation group were both higher than those in control group,while the incidence of cerebral infarction in observation group was lower than that in control group(all P<0.05).No significant difference of general data nor other surgical data was found between groups(all P>0.05).Acute encephalocele occurred in 1 case in observation group during operation,and cranial ultrasound accurately showed the contralateral secondary epidural hematoma.Increased intracranial pressure in different degrees were found in all 15 cases(15/15,100%)in observation group after operation with transcranial color coded Doppler(TCCD)or transcranial Doppler(TCD),while cerebral vascular spasm was observed in 5 cases(5/15,33.33%),among them 4 cases(4/5,80.00%)were diagnosed cerebral infarction based on CT examination.Conclusion Cranial ultrasound could be used to evaluate changes of sTBI in perioperative period and guide adjusting treatment strategy in time,being valuable for reducing risk of postoperative cerebral infarction and improving prognosis.展开更多
基金financial support from the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0708)the National Natural Science Foundation of China(No.41941018)the Special Fund of Yueqi Scholars(No.800015Z1207).
文摘The control of large deformation problems in layered soft rock tunnels needs to solve urgently.The roof problem is particularly severe among the deformation issues in tunnels.This study first analyzes the asymmetric deformation modes in layered soft rock tunnels with large deformations.Subsequently,we construct a mechanical model under ideal conditions for controlling the roof of layered soft rock tunnels through high preload with the support of NPR anchor cables.The prominent roles of long and short NPR anchor cables in the support system are also analyzed.The results indicate the significance of high preload in controlling the roof of layered soft rock tunnels.The short NPR anchor cables effectively improve the integrity of the stratified soft rock layers,while the long NPR anchor cables effectively mobilize the self-bearing capacity of deep-stable rock layers.Finally,the high-preload support method with NPR anchor cables is validated to have a good effect on controlling large deformations in layered soft rock tunnels through field monitoring data.
文摘Objective To observe the value of cranial ultrasound for perioperative patients with acute severe traumatic brain injury(sTBI).Methods Data of 55 sTBI patients who underwent craniotomy were retrospectively analyzed.The patients were divided into observation group(n=15)and control group(n=40)according to received perioperative cranial ultrasound or not.The general data and surgical data were compared between groups,and ultrasonic data of observation group were analyzed.Results The proportions of good prognosis 1 and 6 months after operation in observation group were both higher than those in control group,while the incidence of cerebral infarction in observation group was lower than that in control group(all P<0.05).No significant difference of general data nor other surgical data was found between groups(all P>0.05).Acute encephalocele occurred in 1 case in observation group during operation,and cranial ultrasound accurately showed the contralateral secondary epidural hematoma.Increased intracranial pressure in different degrees were found in all 15 cases(15/15,100%)in observation group after operation with transcranial color coded Doppler(TCCD)or transcranial Doppler(TCD),while cerebral vascular spasm was observed in 5 cases(5/15,33.33%),among them 4 cases(4/5,80.00%)were diagnosed cerebral infarction based on CT examination.Conclusion Cranial ultrasound could be used to evaluate changes of sTBI in perioperative period and guide adjusting treatment strategy in time,being valuable for reducing risk of postoperative cerebral infarction and improving prognosis.
