Rock sheds are widely used to prevent rockfall disasters along roads in mountainous areas.To improve the capacity of rock sheds for resisting rockfall impact,a sand and expandable polyethylene(EPE)composite cushion wa...Rock sheds are widely used to prevent rockfall disasters along roads in mountainous areas.To improve the capacity of rock sheds for resisting rockfall impact,a sand and expandable polyethylene(EPE)composite cushion was proposed.A series of model experiments of rockfall impact on rock sheds were conducted,and the buried depth of the EPE foam board in the sand layer was considered.The impact load and dynamic response of the rock shed were investigated.The results show that the maximum impact load and dynamic response of the rock shed roof are all significantly less than those of the sand cushion.Moreover,as the distance between the EPE foam board and rock shed roof decreases,the maximum rockfall impact force and impact pressure gradually decrease,and the maximum displacement,acceleration and strain of the rock shed first decrease and then change little.In addition,the vibration acceleration and vertical displacement of the rock shed roof decrease from the centre to the edge and decrease faster along the longitudinal direction than that along the transverse direction.In conclusion,the buffering effect of the sand-EPE composite cushion is better than that of the pure sand cushion,and the EPE foam board at a depth of 1/3 the thickness of the sand layer is appropriate.展开更多
目的全面收集国内外立体定向放射治疗(SBRT)和射频消融(RFA)治疗肝细胞癌(HCC)相关研究文献,通过Meta分析系统比较这两种治疗方法的临床效果及相关并发症。方法计算机检索PubMed、Embase、Cochrane Library、Scopus、Web of Science以...目的全面收集国内外立体定向放射治疗(SBRT)和射频消融(RFA)治疗肝细胞癌(HCC)相关研究文献,通过Meta分析系统比较这两种治疗方法的临床效果及相关并发症。方法计算机检索PubMed、Embase、Cochrane Library、Scopus、Web of Science以及中国生物医学文献(CBM)、知网、万方、维普等中英文数据库自建库至2022年6月发表的SBRT和RFA临床治疗HCC文献。采用Stata 14.0软件进行Meta分析。结果共纳入14项回顾性研究6806例患者。基于总生存期(OS)的综合风险比(HR)结果显示SBRT术后OS低于RFA术后(HR=1.25,95%CI=1.10~1.43,I^(2)=0%,P=0.0009),而局部控制(LC)比率的综合HR显示SBRT有更好的疗效(HR=0.61,95%CI=0.47~0.78,I^(2)=0%,P=0.0001)。亚组分析显示,LC比率的综合HR更支持对肿瘤直径>2 cm患者行SBRT(HR=2.64,95%CI=1.56~4.48,I^(2)=0%,P=0.0003)。SBRT组与RFA组间晚期严重不良反应发生率差异无统计学意义(OR=1.01,95%CI=0.59~1.73,I^(2)=30%,P=0.97)。结论SBRT与RFA相比虽未表现出生存获益上的优势,但在HCC局部控制方面表现出较优的效果,尤其是对肿瘤直径>2 cm的患者。展开更多
基金supported by the Natural Science Foundation of Sichuan Province(No.2022NSFSC1127)the Fundamental Research Funds for the Central Universities(No.2682023CX075).
文摘Rock sheds are widely used to prevent rockfall disasters along roads in mountainous areas.To improve the capacity of rock sheds for resisting rockfall impact,a sand and expandable polyethylene(EPE)composite cushion was proposed.A series of model experiments of rockfall impact on rock sheds were conducted,and the buried depth of the EPE foam board in the sand layer was considered.The impact load and dynamic response of the rock shed were investigated.The results show that the maximum impact load and dynamic response of the rock shed roof are all significantly less than those of the sand cushion.Moreover,as the distance between the EPE foam board and rock shed roof decreases,the maximum rockfall impact force and impact pressure gradually decrease,and the maximum displacement,acceleration and strain of the rock shed first decrease and then change little.In addition,the vibration acceleration and vertical displacement of the rock shed roof decrease from the centre to the edge and decrease faster along the longitudinal direction than that along the transverse direction.In conclusion,the buffering effect of the sand-EPE composite cushion is better than that of the pure sand cushion,and the EPE foam board at a depth of 1/3 the thickness of the sand layer is appropriate.
