Abstract
The coupling calculation model of tunnel and surrounding rock is established by the finite difference method, and the main design parameters of lining structure of single-track ballasted tunnel under 40-ton axle load, heavy train load, are studied in combination with cumulative damage mechanism of surrounding rock at tunnel bottom and the fatigue life characteristics of concrete structure at tunnel bottom. The results show that (1) inverted arch shall be set in sections of III-grade and above. Whether an invert is set in sections of II-grade and below shall be determined according to lithology and groundwater conditions. When the surrounding rock condition is good and the tunnel bottom structure (without invert structure) is adopted, the thickness is recommended to be more than 20 cm, and the concrete strength grade should not be lower than C35. (2) Connection mode: the inverted arch and side wall of the tunnel should be connected in sequence to reduce the stress concentration and improve the stress state of the connection part between the inverted arch and the side wall. (3) It is suggested that the rise-span ratio of invert of single-track tunnel should be 1/6 ∼ 1/8; the larger value should be taken when the surrounding rock condition is poor and the small value should be taken when the surrounding rock condition is good. (4) The thickness of inverted arch is recommended to be no less than 20 cm under the condition of V-grade surrounding rock, to be no less than 15 cm under IV-grade surrounding rock, and to be no less than 10 cm under the condition of III-grade surrounding rock and II-grade surrounding rock sections requiring inverted arch. (5) The recommended value of bedding thickness meeting the design service life is 20 cm under the condition of II-grade surrounding rock.
Highlights
Heavy-haul railway has become the best choice for transporting bulk goods in the world because of its advantages of large volume, high speed, low energy consumption, and low cost
(3) It is suggested that the rise-span ratio of invert of single-track tunnel should be 1/6 ∼ 1/8; the larger value should be taken when the surrounding rock condition is poor and the small value should be taken when the surrounding rock condition is good. (4) e thickness of inverted arch is recommended to be no less than 20 cm under the condition of V-grade surrounding rock, to be no less than 15 cm under IV-grade surrounding rock, and to be no less than 10 cm under the condition of III-grade surrounding rock and II-grade surrounding rock sections requiring inverted arch. (5) e recommended value of bedding thickness meeting the design service life is 20 cm under the condition of II-grade surrounding rock
Jakobsen obtained the relationship between ground vibration level and relevant track parameters through field test of ground vibration caused by train load [1]
Summary
Heavy-haul railway has become the best choice for transporting bulk goods in the world because of its advantages of large volume, high speed, low energy consumption, and low cost. Based on a heavy-haul railway tunnel project, Zou et al studied the stress distribution and dynamic response of the foundation structure of heavy-haul railway tunnel under the action of train load of 30-ton axle load combined with field vehicle test and numerical simulation [3]. The coupling calculation model of tunnel and surrounding rock is established by the finite difference method, and the main design parameters of lining structure of single-track ballasted tunnel under 40-ton axle load heavy train load are studied in combination with cumulative damage mechanism of surrounding rock at tunnel bottom and the fatigue life characteristics of concrete structure at tunnel bottom. 2. Dynamic Performance Analysis of Tunnel Bottom Structure e finite difference method is used to establish a dynamic numerical analysis model to calculate the dynamic response characteristics of the foundation structure of heavy-haul railway tunnel under the action of train load
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