When assessing the sliding stability of a concrete dam,the influence of large-scale asperities in the sliding plane is often ignored due to limitations of the analytical rigid body assessment methods provided by curre...When assessing the sliding stability of a concrete dam,the influence of large-scale asperities in the sliding plane is often ignored due to limitations of the analytical rigid body assessment methods provided by current dam assessment guidelines.However,these asperities can potentially improve the load capacity of a concrete dam in terms of sliding stability.Although their influence in a sliding plane has been thoroughly studied for direct shear,their influence under eccentric loading,as in the case of dams,is unknown.This paper presents the results of a parametric study that used finite element analysis(FEA)to investigate the influence of large-scale asperities on the load capacity of small buttress dams.By varying the inclination and location of an asperity located in the concrete-rock interface along with the strength of the rock foundation material,transitions between different failure modes and correlations between the load capacity and the varied parameters were observed.The results indicated that the inclination of the asperity had a significant impact on the failure mode.When the inclinationwas 30and greater,interlocking occurred between the dam and foundation and the governing failure modes were either rupture of the dam body or asperity.When the asperity inclination was significant enough to provide interlocking,the load capacity of the dam was impacted by the strength of the rock in the foundation through influencing the load capacity of the asperity.The location of the asperity along the concrete-rock interface did not affect the failure mode,except for when the asperity was located at the toe of the dam,but had an influence on the load capacity when the failure occurred by rupture of the buttress or by sliding.By accounting for a single large-scale asperity in the concrete-rock interface of the analysed dam,a horizontal load capacity increase of 30%e160%was obtained,depending on the inclination and location of the asperity and the strength of the foundation material.展开更多
Introduction: Proximal femoral nail is a better choice of implant for the treatment of an unstable trochanteric fracture, however it is associated with screw migration and cutout because of greater trochanteric commin...Introduction: Proximal femoral nail is a better choice of implant for the treatment of an unstable trochanteric fracture, however it is associated with screw migration and cutout because of greater trochanteric comminution and coronal split. This study is to evaluate the results of Trochanteric Buttress Plate (TBP) combined with PFN in an unstable IT fractures for buttressing lateral wall and reinforcing fixation. Materials and Methods: We carried out a consecutive study of 32 patients of Unstable intertrochanteric fracture femur with lateral wall comminution. It was studied at Ashwini Sahakari Rugnalaya and Sanshodhan Kendra Solapur India and Government medical college Chandrapur India from April-2015 to December-2017 using innovative Trochanteric buttress plate along with PFN. Eighteen male and fourteen female in the age group of 55 to 80 years were included in the study. There were 26 cases of A3 and six cases of A2 were fixed by PFN combined with trochanteric buttress plate to augment the comminuted lateral wall. Results: The bone healing is observed in all the cases in the mean period of 12.6 weeks. Four patients developed complications, including lateral migration of neck screws (n = 2), superficial infection (n = 2). Patients were followed up for a mean of 10.6 months. At the end of follow-up the Salvati and Wilson hip function was 36 (out of 40) in 87.5% of patients [twenty eight patients]. The clinical, radiological and functional outcomes were found to be satisfactory. Conclusion: The stabilization of lateral trochanteric wall with trochanteric buttress plate restores anatomy, increases the stability of construct and prevents inherent complication of screw migration and cutout.展开更多
We describe patterns of buttress formation and development in eleven tree species at Lawachara National Park, Bangladesh. Forty-five percent of trees of these 11 species had buttresses. Artocarpus chaplasha Roxb. show...We describe patterns of buttress formation and development in eleven tree species at Lawachara National Park, Bangladesh. Forty-five percent of trees of these 11 species had buttresses. Artocarpus chaplasha Roxb. showed maximum （87%） buttress formation, whereas Alstonia scholaris （L.） R. Br. did not show any buttress. Buttresses were recorded in 20%-40% of trees of six species and 40%-60% of trees in three species. Mean length and height of buttress varied among the species and ranged from 0.37-4.37 m and 0.71-2.13 m, respectively. Buttress height, mean buttress length, total buttress length, and total length plus length of secondaries increased with DBH （diameter at breast height） and tree height. Buttress number did not increase with DBH or tree height. Under-storey and mid-canopy trees produced less developed buttresses than did emergent trees （p〈0.01）. Wood density showed moderate effects on buttress characters （p〈0.05）, while the slope of the land did not. Canopy category was a primary regulating factor for tree buttressing, suggesting that buttresses are mechanical adaptations of trees to counter physical stresses.展开更多
To assess the effect of using buttress plate associated with antografting of fibula and iliac bone for the treatment of distal femoral C3 type fracture.Methods Seventeen cases of distal femoral C3 type fracture usin...To assess the effect of using buttress plate associated with antografting of fibula and iliac bone for the treatment of distal femoral C3 type fracture.Methods Seventeen cases of distal femoral C3 type fracture using buttress plate associated with antografting of fibula and iliac bone were analyzed retrospectively.Results All cases were followed up for an average of 24 months（8～55 months）.The average time of octets bridge forming were 4 months（3～5 months） while the average time for bone union were 8 months （6～14 months）.According to Shelbourne rating system,result of all 18 cases were excellent and no malunion,infection were found.Conclusion Buttress plate associated with antografting of fibula and iliac bone is an effective alternative for the treatment of distal femoral C3 type fracture.It can provide more stable fixation to the bone and earlier functional exercises can be achieved.5 refs,3 figs,1 tab.展开更多
Purpose:Intramedullary implants are well accepted fixation of all types of intertrochanteric(IT)frac-tures,both stable and unstable types.Intramedullary nails have an ability to effectively support the posteromedial p...Purpose:Intramedullary implants are well accepted fixation of all types of intertrochanteric(IT)frac-tures,both stable and unstable types.Intramedullary nails have an ability to effectively support the posteromedial part,but fail to buttress the broken lateral wall requiring lateral augmentation.The aim of this study was to evaluate the outcome of proximal femoral nail augmented with trochanteric buttress plate for broken lateral wall with IT fractures,which was fixed to the femur through hip screw and anti-rotation screw nail.Methods:Of 30 patients,20 had Jensen-Evan typeⅢand 10 had type V fractures.Patients with IT fracture of broken lateral wall and aged more than 18 years,in whom satisfactory reduction was achieved by closed methods,were included in the study.Patients with pathologic or open fractures,polytrauma,prior hip surgery,non-ambulatory prior to surgery,and those who refused to participate were excluded.The operative time,blood loss,radiation exposure,quality of reduction,functional outcome,and union time were evaluated.All data were coded and recorded in Microsoft Excel spread sheet program.SPSS 20.0 was used for data analysis and normality of the continuous data was checked using Kolmogorv Smirnov test.Results:The mean age of patients in the study was 60.3 years.The mean duration of surgery(min),mean intra-operative blood loss(mL)and mean number of exposures were 91.86±12.8(range 70-122),144.8±3.6(range 116-208),and 56.6(range 38-112),respectively.The mean union time was 11.6 weeks and the mean Harris hip score was 94.1.Conclusion:Lateral trochanteric wall in IT fractures is significantly important,and needs to be recon-structed adequately.Nail-plate construct of trochanteric buttress plate fixed with hip screw and anti-rotation screw of proximal femoral nail can be successfully used to augment,fix or buttress the lateral trochanteric wall giving excellent to good results of early union and reduction.展开更多
Aims buttresses are prevalent and are important to many ecological processes in tropical rainforests but are overlooked in many rainforest studies.based on a buttress survey in a 20-hectare plot,this study aims to ans...Aims buttresses are prevalent and are important to many ecological processes in tropical rainforests but are overlooked in many rainforest studies.based on a buttress survey in a 20-hectare plot,this study aims to answer the following questions:(i)is buttress forming a fixed species characteristic?(ii)is there any phylogenetic signal for buttress forming across a broad taxonomic scale?(iii)is buttress form-ing an inherent feature or simply induced by environmental factors,and how is this relevant to the size of the tree?Methods We surveyed buttresses for all 95940 trees with diameter at breast height(DbH)≥10 mm in a 20-ha tropical dipterocarp rainforest in Xishuangbanna,sW China.The occurrence of buttresses was compared across different taxa and across different tree-size classes.a phylogenetic analysis was conducted among buttressed and non-buttressed species in order to understand the evolutionary background of buttress formation.Important Findings This preliminary study showed that buttress trees are very abundant(making up 32%of trees with≥100 mm DbH)in this 20-ha tropical rainforest situated at the northern edge of the tropics.Fifty-one percent of the 468 tree species in the plot had stems that produced buttresses.large trees were more likely to develop buttresses than smaller ones.We found that although buttress formation is not a fixed species characteristic,there is a strong phylogenetic signal for buttress formation in larger species.展开更多
基金the Research Council of Norway(Grant No.244029)the project‘Stable dams’,FORMAS(Grant No.2019e01236)+1 种基金the project‘Improved safety assessment of concrete dams’,and SVC(Grant No.VKU32019)the project‘Safe dams’,that supported the development of the research presented in this article.
文摘When assessing the sliding stability of a concrete dam,the influence of large-scale asperities in the sliding plane is often ignored due to limitations of the analytical rigid body assessment methods provided by current dam assessment guidelines.However,these asperities can potentially improve the load capacity of a concrete dam in terms of sliding stability.Although their influence in a sliding plane has been thoroughly studied for direct shear,their influence under eccentric loading,as in the case of dams,is unknown.This paper presents the results of a parametric study that used finite element analysis(FEA)to investigate the influence of large-scale asperities on the load capacity of small buttress dams.By varying the inclination and location of an asperity located in the concrete-rock interface along with the strength of the rock foundation material,transitions between different failure modes and correlations between the load capacity and the varied parameters were observed.The results indicated that the inclination of the asperity had a significant impact on the failure mode.When the inclinationwas 30and greater,interlocking occurred between the dam and foundation and the governing failure modes were either rupture of the dam body or asperity.When the asperity inclination was significant enough to provide interlocking,the load capacity of the dam was impacted by the strength of the rock in the foundation through influencing the load capacity of the asperity.The location of the asperity along the concrete-rock interface did not affect the failure mode,except for when the asperity was located at the toe of the dam,but had an influence on the load capacity when the failure occurred by rupture of the buttress or by sliding.By accounting for a single large-scale asperity in the concrete-rock interface of the analysed dam,a horizontal load capacity increase of 30%e160%was obtained,depending on the inclination and location of the asperity and the strength of the foundation material.
文摘Introduction: Proximal femoral nail is a better choice of implant for the treatment of an unstable trochanteric fracture, however it is associated with screw migration and cutout because of greater trochanteric comminution and coronal split. This study is to evaluate the results of Trochanteric Buttress Plate (TBP) combined with PFN in an unstable IT fractures for buttressing lateral wall and reinforcing fixation. Materials and Methods: We carried out a consecutive study of 32 patients of Unstable intertrochanteric fracture femur with lateral wall comminution. It was studied at Ashwini Sahakari Rugnalaya and Sanshodhan Kendra Solapur India and Government medical college Chandrapur India from April-2015 to December-2017 using innovative Trochanteric buttress plate along with PFN. Eighteen male and fourteen female in the age group of 55 to 80 years were included in the study. There were 26 cases of A3 and six cases of A2 were fixed by PFN combined with trochanteric buttress plate to augment the comminuted lateral wall. Results: The bone healing is observed in all the cases in the mean period of 12.6 weeks. Four patients developed complications, including lateral migration of neck screws (n = 2), superficial infection (n = 2). Patients were followed up for a mean of 10.6 months. At the end of follow-up the Salvati and Wilson hip function was 36 (out of 40) in 87.5% of patients [twenty eight patients]. The clinical, radiological and functional outcomes were found to be satisfactory. Conclusion: The stabilization of lateral trochanteric wall with trochanteric buttress plate restores anatomy, increases the stability of construct and prevents inherent complication of screw migration and cutout.
文摘We describe patterns of buttress formation and development in eleven tree species at Lawachara National Park, Bangladesh. Forty-five percent of trees of these 11 species had buttresses. Artocarpus chaplasha Roxb. showed maximum （87%） buttress formation, whereas Alstonia scholaris （L.） R. Br. did not show any buttress. Buttresses were recorded in 20%-40% of trees of six species and 40%-60% of trees in three species. Mean length and height of buttress varied among the species and ranged from 0.37-4.37 m and 0.71-2.13 m, respectively. Buttress height, mean buttress length, total buttress length, and total length plus length of secondaries increased with DBH （diameter at breast height） and tree height. Buttress number did not increase with DBH or tree height. Under-storey and mid-canopy trees produced less developed buttresses than did emergent trees （p〈0.01）. Wood density showed moderate effects on buttress characters （p〈0.05）, while the slope of the land did not. Canopy category was a primary regulating factor for tree buttressing, suggesting that buttresses are mechanical adaptations of trees to counter physical stresses.
文摘To assess the effect of using buttress plate associated with antografting of fibula and iliac bone for the treatment of distal femoral C3 type fracture.Methods Seventeen cases of distal femoral C3 type fracture using buttress plate associated with antografting of fibula and iliac bone were analyzed retrospectively.Results All cases were followed up for an average of 24 months（8～55 months）.The average time of octets bridge forming were 4 months（3～5 months） while the average time for bone union were 8 months （6～14 months）.According to Shelbourne rating system,result of all 18 cases were excellent and no malunion,infection were found.Conclusion Buttress plate associated with antografting of fibula and iliac bone is an effective alternative for the treatment of distal femoral C3 type fracture.It can provide more stable fixation to the bone and earlier functional exercises can be achieved.5 refs,3 figs,1 tab.
文摘Purpose:Intramedullary implants are well accepted fixation of all types of intertrochanteric(IT)frac-tures,both stable and unstable types.Intramedullary nails have an ability to effectively support the posteromedial part,but fail to buttress the broken lateral wall requiring lateral augmentation.The aim of this study was to evaluate the outcome of proximal femoral nail augmented with trochanteric buttress plate for broken lateral wall with IT fractures,which was fixed to the femur through hip screw and anti-rotation screw nail.Methods:Of 30 patients,20 had Jensen-Evan typeⅢand 10 had type V fractures.Patients with IT fracture of broken lateral wall and aged more than 18 years,in whom satisfactory reduction was achieved by closed methods,were included in the study.Patients with pathologic or open fractures,polytrauma,prior hip surgery,non-ambulatory prior to surgery,and those who refused to participate were excluded.The operative time,blood loss,radiation exposure,quality of reduction,functional outcome,and union time were evaluated.All data were coded and recorded in Microsoft Excel spread sheet program.SPSS 20.0 was used for data analysis and normality of the continuous data was checked using Kolmogorv Smirnov test.Results:The mean age of patients in the study was 60.3 years.The mean duration of surgery(min),mean intra-operative blood loss(mL)and mean number of exposures were 91.86±12.8(range 70-122),144.8±3.6(range 116-208),and 56.6(range 38-112),respectively.The mean union time was 11.6 weeks and the mean Harris hip score was 94.1.Conclusion:Lateral trochanteric wall in IT fractures is significantly important,and needs to be recon-structed adequately.Nail-plate construct of trochanteric buttress plate fixed with hip screw and anti-rotation screw of proximal femoral nail can be successfully used to augment,fix or buttress the lateral trochanteric wall giving excellent to good results of early union and reduction.
基金National Natural Science Foundation of China(31070411)the Biodiversity Committee of the Chinese Academy of Sciences.
文摘Aims buttresses are prevalent and are important to many ecological processes in tropical rainforests but are overlooked in many rainforest studies.based on a buttress survey in a 20-hectare plot,this study aims to answer the following questions:(i)is buttress forming a fixed species characteristic?(ii)is there any phylogenetic signal for buttress forming across a broad taxonomic scale?(iii)is buttress form-ing an inherent feature or simply induced by environmental factors,and how is this relevant to the size of the tree?Methods We surveyed buttresses for all 95940 trees with diameter at breast height(DbH)≥10 mm in a 20-ha tropical dipterocarp rainforest in Xishuangbanna,sW China.The occurrence of buttresses was compared across different taxa and across different tree-size classes.a phylogenetic analysis was conducted among buttressed and non-buttressed species in order to understand the evolutionary background of buttress formation.Important Findings This preliminary study showed that buttress trees are very abundant(making up 32%of trees with≥100 mm DbH)in this 20-ha tropical rainforest situated at the northern edge of the tropics.Fifty-one percent of the 468 tree species in the plot had stems that produced buttresses.large trees were more likely to develop buttresses than smaller ones.We found that although buttress formation is not a fixed species characteristic,there is a strong phylogenetic signal for buttress formation in larger species.
