| With the sustained and rapid development of our country economic, urban rail transitespecially subway in China’s provincial cities has started planning and construction, theenvironmental vibration and noise issues which caused by subway are also increasinglysignificant, Especially when the subway through the conservation area, it is much attention ofthe impact of vibration on the ancient buildings. Caused many problems for the subway,scholars has been made many study which is from the subway run random vibration loadsgenerated,the spread vibration propagation and attenuation in the medium, building dynamicresponse characteristics and safety assessment aspects of the study, and put forward thedamping measures.Based on the rail transit line1in Lanzhou, the vibration control standards of structuralsafety of domestic and foreign were comprehensive research, we provided the appropriatevibration limit standard of the white Temple Tower under the Lanzhou Metro features. Basedon the finite element analysis software MIDAS-GTS, the tunnel-floating slab track-foundation soil-white Temple Tower overall finite element dynamic model was established.Enter the existing tunnel design parameters, dynamic loads and soil dynamics parameters, thedynamic response of the white Temple Tower was analysised, it cause by subway trainoperation. When the train is running at design speed, the results showed that the dynamicresponse point of maximum horizontal speed of0.37mm/s is greater than0.25mm/s, itdoes not meet the key heritage vibration control requirements of the standard, the dampingmeasures need to be taken.In order to ensure the safety of the white Temple Tower, consider the use of springfloating channel plate damping measures, the impact of the vibration damping researchedfrom running speed, rail fastener stiffness, floating slab spring stiffness, the fasteners dampingand floating slab damping, and comparison the front and rear damping. The results show that:(1) the dynamic response of point velocity and acceleration at different operating speedsincrease with the increase of the speed of traffic,it is very significant that the response ofdriving speed.(2) The response point’s velocity and acceleration significantly reduced withthe axis line distance of dynamic response point and the tunnel to increase.(3) When thefastener stiffness is less than4.0×107N/m, the speed and acceleration of the response pointswere reduced from50.7%to60.0%and from47.1%to52.3%, when more than8.0×107N/m, all the dynamic response is flatten, it is recommended under rail stiffness value of4.0×107~8.0×107N/m;(4) When the board of the floating support stiffness less than4.0× 107N/m, the dynamic response of point velocity and acceleration respectively increased by79.2%to83.6%and from80.5%to84.3%, between4.0×107at8.0×107N/m, thedynamic response is flatten, when greater than8.0×107N/m, power response speed andacceleration of a trend is decreased, the proposed floating board support stiffness value is1.0×107to4.0×107N/m;(5) when the fastener damping is less than4.0×104N m/s,vertical speed and the vertical acceleration of the dynamic response of points were reducedfrom42.6%to48.5%and from41.5%to48.7%, and when greater than8.0×104N m/s,the dynamic response is flatten, the proposed fasteners damping value is4.0×104to8.0×104N m/s;(6) When the floating slab damping is less than4.0×104N m/s, verticalspeed and the vertical acceleration of the dynamic response of points were reduced from44.3%to49.5%and from42.5%to46.7%, and greater than8.0×10~4N m/s, the dynamicresponse is flatten, the proposed floating slab under damping take value of4.0×104to8.0×104N m/s;(7) When the under rail fasteners, floating channel plate spring parameter valuesrecommended by this article, the dynamic response of point velocity and accelerationcomparable floating channel plate reduced by66%to72%, the damping effect is significant. |
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