D-type Construction For Beam Dynamic Security Features Pilot Study

When the underpass bridge frame structure in the Ganlong Line from Ganzhou of Jiangxi province to Longyan of Fujian province below which is the Jingjiu Line is carried out with jack-in method, Jingjiu Line is supported by 6 pairs of temporary beams in the pattern of D16+ D24+ D16 to ensure the normal function of it. To guarantee the security of the traveling train and minimize the influence on transportion during the whole course of the construction, raising the traveling speed to satisfy the requirement of 'double sixty' is propounded which breakthroughs the velocity limitation of 45km/h confined by actual 'Security Regulation of railway Track District'. Based on the purpose, in this paper the experimental and theoretical research on the dynamic characteristics and security of temporary beams is carried out when the velocity limitation arrives 60km/h and more than. Thus the influences on the security of traveling train with dynamic parameters variations of track, temporary beams and piles are researched.To satisfy the request of test, the test is divided into three phases: velocity limitation phase, test of experimental train phase, and monitoring phase, which test the coefficient of derailment, rate of wheel load reduction, and the gage elastically widened of rail gauge, and natural frequency, dynamic deflection, impact coefficient of temporary beam,and longitudinal and transversal displacements of the top of pile. Otherwise, in this paper, the special FEM program of ANSYS5.7 is applied to calculate the dynamic deflection and the natural frequency of vibration of temporary beam, and the values calculated are compared to that measured and they are in agreement with each other well. Thus, the evaluation of the stiffness and security of temporary beam is obtained.Based on the results of experiment and theoretical analysis, a perfect evaluation of security of the traveling crane, as well as monitoring the security of the traveling train during the whole course, is gained. The evaluation indicates that it can sastisfy the relevant requirement of actual 'Security Regulation of railway Track District' when the velocity limitation is raised from 45km/h to 60km/h, and it also provides important parameters for the improvement of velocity limitation and guaranteeing the security of the traveling crane when tunnel under construction.