This paper proposes a theoretical method that can be used in calculating the stability of coral reefs or artificial islands.In this work,we employ the variational limiting equilibrium procedure to theoretically determ...This paper proposes a theoretical method that can be used in calculating the stability of coral reefs or artificial islands.In this work,we employ the variational limiting equilibrium procedure to theoretically determine the slope stability of coral reefs covered with hard reef shells as a result of horizontal wave loads.A reasonable functional is proposed and its extremum is calculated based on the conservation of energy.Then,we deduce the stability factor Ns of coral reefs under combined vertical self-gravity and horizontal wave loads,which is consistent with the published results.We compare some classic examples of homogeneous slopes without hard shells in order to analyze the accuracy of results generated by this variational procedure.The variational results are accurate and reliable according to the results of a series of detailed calculations and comparisons.Simultaneously,some other influence parameters on the reef stability,including the top-layer tensile strength of coral reef,the amplitude of wave loading,and the tensile crack,are calculated and discussed in detail.The analysis results reveal that the existence of a hard reef shell could enhance the stability of reef slope and that there is a nonlinear relationship between the stability factor Ns,the shear strength,and the thickness Ds of the covered coral reef shell.Furthermore,the emergence of top-layer tensile cracks on the coral reefs reduces their stability,and the action of horizontal wave loads greatly decreases the stability of coral reefs.Thus,the hard shell strength and its thickness Ds,surface tensile crack,and wave loading require more careful attention in the field of practical engineering.展开更多
背景:涉及距下关节的跟骨关节内骨折约占全部跟骨骨折的75%,而对于移位型跟骨关节内骨折,手术治疗要优于非手术治疗。然而对于治疗时机、手术指征、切口选择、是否植骨等问题目前仍有争议。经典的“L”型入路因其较高的切口并发症而有...背景:涉及距下关节的跟骨关节内骨折约占全部跟骨骨折的75%,而对于移位型跟骨关节内骨折,手术治疗要优于非手术治疗。然而对于治疗时机、手术指征、切口选择、是否植骨等问题目前仍有争议。经典的“L”型入路因其较高的切口并发症而有逐渐被微创内固定所取代的趋势。目的:比较撬拨复位微创置板及“L”型切口切开复位钢板内固定治疗SandersⅡ、Ⅲ型跟骨骨折的临床疗效。方法:选择汕头市中医院骨二科2016年1月至2019年1月收治的SandersⅡ、Ⅲ型跟骨骨折患者60例,随机分为撬拨复位微创置板组(n=32)和“L”型切口组(n=28),分别采用闭合撬拨复位微创置板和经“L”型切口切开复位钢板内固定治疗。术后6个月末次随访按美国矫形外科足踝协会评分优良率评价2组手术疗效,对比2组患者术前等待天数、手术时间、住院天数及并发症发生率,术前、术后及末次随访时分别测定患者Böhler角、Gissane角并加以比较。结果与结论:①撬拨复位微创置板组美国矫形外科足踝协会评分优良率为91%,“L”型切口组为93%,2组比较差异无显著性意义(P>0.05);②2组术后Böhler角、Gissane角均较术前明显改善(P<0.05);术后1 d 2组Gissane角相当(P>0.05),Böhler角变化“L”型切口组优于撬拨复位微创置板组(P<0.05);末次随访2组Böhler角及Gissane角均有不同程度丢失,差异无显著性意义(P>0.05);③“L”型切口组患者的术前等待天数、住院天数均多于撬拨复位微创置板组(P<0.05);手术时间少于撬拨复位微创置板组(P<0.05);④撬拨复位微创置板组并发症发生率为9%,低于“L”型切口组的32%(P<0.05);⑤提示与传统“L”型切口切开复位内固定相比,撬拨复位微创置板治疗SandersⅡ、Ⅲ型跟骨骨折临床疗效满意,创伤小,并发症少,值得临床推荐。展开更多
基金the Project of National Science and Technology Ministry(No.2014BAB16B03)the National Natural Science Foundation of China(No.51679224)。
文摘This paper proposes a theoretical method that can be used in calculating the stability of coral reefs or artificial islands.In this work,we employ the variational limiting equilibrium procedure to theoretically determine the slope stability of coral reefs covered with hard reef shells as a result of horizontal wave loads.A reasonable functional is proposed and its extremum is calculated based on the conservation of energy.Then,we deduce the stability factor Ns of coral reefs under combined vertical self-gravity and horizontal wave loads,which is consistent with the published results.We compare some classic examples of homogeneous slopes without hard shells in order to analyze the accuracy of results generated by this variational procedure.The variational results are accurate and reliable according to the results of a series of detailed calculations and comparisons.Simultaneously,some other influence parameters on the reef stability,including the top-layer tensile strength of coral reef,the amplitude of wave loading,and the tensile crack,are calculated and discussed in detail.The analysis results reveal that the existence of a hard reef shell could enhance the stability of reef slope and that there is a nonlinear relationship between the stability factor Ns,the shear strength,and the thickness Ds of the covered coral reef shell.Furthermore,the emergence of top-layer tensile cracks on the coral reefs reduces their stability,and the action of horizontal wave loads greatly decreases the stability of coral reefs.Thus,the hard shell strength and its thickness Ds,surface tensile crack,and wave loading require more careful attention in the field of practical engineering.
文摘背景:涉及距下关节的跟骨关节内骨折约占全部跟骨骨折的75%,而对于移位型跟骨关节内骨折,手术治疗要优于非手术治疗。然而对于治疗时机、手术指征、切口选择、是否植骨等问题目前仍有争议。经典的“L”型入路因其较高的切口并发症而有逐渐被微创内固定所取代的趋势。目的:比较撬拨复位微创置板及“L”型切口切开复位钢板内固定治疗SandersⅡ、Ⅲ型跟骨骨折的临床疗效。方法:选择汕头市中医院骨二科2016年1月至2019年1月收治的SandersⅡ、Ⅲ型跟骨骨折患者60例,随机分为撬拨复位微创置板组(n=32)和“L”型切口组(n=28),分别采用闭合撬拨复位微创置板和经“L”型切口切开复位钢板内固定治疗。术后6个月末次随访按美国矫形外科足踝协会评分优良率评价2组手术疗效,对比2组患者术前等待天数、手术时间、住院天数及并发症发生率,术前、术后及末次随访时分别测定患者Böhler角、Gissane角并加以比较。结果与结论:①撬拨复位微创置板组美国矫形外科足踝协会评分优良率为91%,“L”型切口组为93%,2组比较差异无显著性意义(P>0.05);②2组术后Böhler角、Gissane角均较术前明显改善(P<0.05);术后1 d 2组Gissane角相当(P>0.05),Böhler角变化“L”型切口组优于撬拨复位微创置板组(P<0.05);末次随访2组Böhler角及Gissane角均有不同程度丢失,差异无显著性意义(P>0.05);③“L”型切口组患者的术前等待天数、住院天数均多于撬拨复位微创置板组(P<0.05);手术时间少于撬拨复位微创置板组(P<0.05);④撬拨复位微创置板组并发症发生率为9%,低于“L”型切口组的32%(P<0.05);⑤提示与传统“L”型切口切开复位内固定相比,撬拨复位微创置板治疗SandersⅡ、Ⅲ型跟骨骨折临床疗效满意,创伤小,并发症少,值得临床推荐。
