| Tunnel ventilation tower is a common structure in tunnel engineering,which plays an irreplaceable role in the construction and operation of the tunnel.The traditional tunnel ventilation tower construction method is first to carry out the shield through,and then the construct the ventilation tower structure,the construction method is widely used and the construction time is long.According to the requirement of shortening the construction period,the new construction method of construction of ventilation tower structure firstly and then carry out the shield through is put forward.In order to study the two construction methods' influence on surface deformation and ventilation tower structure.This paper fully discussed two kinds of method and then the numerical simulation model of the influence of the two methods on the surface deformation and the structure of the ventilation tower is established by using finite element calculation software ABAQUS.Then the simulation results are analyzed.Research the influence of plate thickness and beam height of the underground five floor on the internal force of the frame beam and the vertical displacement of the frame column.The main conclusions are as follows:(1)In the two kinds of construction methods,it is found that the construction step of plain concrete excavation and tunnel segment removal have a great influence on internal force of frame beam and displacement at the bottom of the column during the construction of the two methods of ventilation tower.The position of frame beam affected by the construction process relatively large is position of beam and frame column.Before the excavation and concrete lining is removed,along with construction,the internal force of frame beam decreases gradually.In the whole process of construction,the deformation of the earth's surface is symmetrical.The influence of the construction step of the tunnel excavation on the ground surface deformation is more obvious compared with other construction steps.(2)It is found that when we compare the internal force of the frame beam and the vertical displacement of the bottom of the frame column between the traditional construction method and the new construction method,the numerical value of the traditional construction method is less than that of the new construction method,the bending moment at both ends of the frame beam is particularly obvious.Therefore,when the numerical value of these two aspects is used as the evaluation criterion of construction method,traditional construction method is better than the new construction method.(3)The vertical displacement of the column bottom of the frame column in the middle of ventilation tower was found to decrease with the increase of plate thickness and beam height.However,with the increase of the same size,the bottom displacement of the column decreases.With the increase of plate thickness and beam height,the internal force of the underground four floor frame beam is gradually reduced,and the internal force of the underground five floor frame beam is gradually increased.Therefore,when selecting conversion plate thickness and beam height of the new method,should take into account the safety and economy of engineering.In the new method,as for the safety of structure,the conversion plate's thickness and beam height is not the larger size the more favorable.Therefore,when selecting conversion plate thickness and beam height of the new method,should take into account the safety and economy of engineering.The numerical simulation results in this paper can provide reference for the design,construction and monitoring of the construction method of tunnel ventilation tower. |
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