Many rock avalanches were triggered by the Wenchuan earthquake on May 12,2008 in southwest China.Protection galleries covered with a single soil layer are usually used to protect against rockfall.Since one-layer prote...Many rock avalanches were triggered by the Wenchuan earthquake on May 12,2008 in southwest China.Protection galleries covered with a single soil layer are usually used to protect against rockfall.Since one-layer protection galleries do not have sufficient buffer capacity,a two-layered absorbing system has been designed.This study aims to find whether an expanded poly-styrol(EPS) cushion,which is used in the soil-covered protection galleries for shock absorption,could be positioned under dynamic loadings.The dynamic impacts of the two-layered absorbing system under the conditions ofrock avalanches are numerically simulated through a 2D discrete element method.By selecting reasonable parameters,a series of numerical experiments were conducted to find the best combination for the twolayered absorbing system.The values of the EPS layer area as a percentage of the total area were set as 0%(S1),22%(S2),and 70%(S3).22% of the area of the EPS layer was found to be a reasonable value,and experiments were conducted to find the best position of the EPS layer in the two-layered absorbing system.The numerical results yield useful conclusions regarding the interaction between the impacting avalanches and the two-layered absorbing system.The soil layer can absorb the shock energy effectively and S2(0.4-m thick EPS cushion covered with soillayer) is the most efficient combination,which can reduce the impact force,compared with the other combinations.展开更多
This paper presents the effect of thickness of Buffer layer on the safety of cut-and-cover tunnel under the given magnitude and height of rockfall, and the limit load of the structure. To establish calculating models ...This paper presents the effect of thickness of Buffer layer on the safety of cut-and-cover tunnel under the given magnitude and height of rockfall, and the limit load of the structure. To establish calculating models of rockfall in different conditions, the dynamics of the fall down to the surface of the slope is taken into account and the exterior characteristics of the rockfall is analyzed. We have derived the formula for calculating velocity of rocks before and after collision, calculated the impact load upon the structures below and the limit load, and compared the impact force and limit load to judge the safety of the structure. Finally, the validity of models is approved by the safety evaluation of cut-and-cover tunnel in the mouth of Heshang Mountain in Nandan County.展开更多
基金financial support from the Project of National Science Foundation of China(Grant No.41272346)the National Outstanding Youth Funds(Grant No.41225011)+2 种基金financial support from the Science & Technology Research Plan of China Railway Eryuan Engineering Group CO.LTD (Grant No.13164196(13-15))the Project of National Science Foundation of China(Grant Nos. 41472293,91430105)"hundred talents" program of CAS
文摘Many rock avalanches were triggered by the Wenchuan earthquake on May 12,2008 in southwest China.Protection galleries covered with a single soil layer are usually used to protect against rockfall.Since one-layer protection galleries do not have sufficient buffer capacity,a two-layered absorbing system has been designed.This study aims to find whether an expanded poly-styrol(EPS) cushion,which is used in the soil-covered protection galleries for shock absorption,could be positioned under dynamic loadings.The dynamic impacts of the two-layered absorbing system under the conditions ofrock avalanches are numerically simulated through a 2D discrete element method.By selecting reasonable parameters,a series of numerical experiments were conducted to find the best combination for the twolayered absorbing system.The values of the EPS layer area as a percentage of the total area were set as 0%(S1),22%(S2),and 70%(S3).22% of the area of the EPS layer was found to be a reasonable value,and experiments were conducted to find the best position of the EPS layer in the two-layered absorbing system.The numerical results yield useful conclusions regarding the interaction between the impacting avalanches and the two-layered absorbing system.The soil layer can absorb the shock energy effectively and S2(0.4-m thick EPS cushion covered with soillayer) is the most efficient combination,which can reduce the impact force,compared with the other combinations.
文摘This paper presents the effect of thickness of Buffer layer on the safety of cut-and-cover tunnel under the given magnitude and height of rockfall, and the limit load of the structure. To establish calculating models of rockfall in different conditions, the dynamics of the fall down to the surface of the slope is taken into account and the exterior characteristics of the rockfall is analyzed. We have derived the formula for calculating velocity of rocks before and after collision, calculated the impact load upon the structures below and the limit load, and compared the impact force and limit load to judge the safety of the structure. Finally, the validity of models is approved by the safety evaluation of cut-and-cover tunnel in the mouth of Heshang Mountain in Nandan County.
