Dynamic Response of Underground Tunnel in Soft Soil under Surface and Subsurface Explosion

In the present paper the model of beam on Winkler-type elastic foundation is used to model the underground tunnel. The soil displacement (mm)-stress (kpa) curve (p-s curve) is approximated in the form of hyperbolic type function by fitting the existing experimental data and then equivalent linear type of nonlinear bedding coefficient of foundation is derived from the fitting curve. Substitute the equivalent coefficient into the vibration equation of beam on Winkler-type elastic foundation, and we may assess the nonlinear effect of soil. Based on the hypothesis of large distance to earthquake source, Rayleigh wave is used to simulate the longitudinal shearing seismic wave. According to the amplitude attenuation law of Rayleigh wave in elastic half place, the effect of structure bury depth on dynamic response of underground tunnel is considered and the conception of critical bury depth is put forward. Finally the vibration differential equation of beam on Winkler-type elastic foundation is solved by using Matlab software, and the dynamic response of underground tunnel at different structure bury depth are compared. The results may provide a reference for practical engineering.

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Vibrations Caused By Train Passages In Underground Tunnel Compared To Vibrations From Ground Surface Transportation – Some Results Of Investigations

Archives of Civil Engineering ◽

10.2478/ace-2014-0018 ◽

2014 ◽

Vol 60 (2) ◽

pp. 269-286

Author(s):

Krzysztof Stypuła

Keyword(s):

Dynamic Response ◽

Ground Surface ◽

Experimental Investigations ◽

Ground Vibrations ◽

Underground Tunnel ◽

Surface Transportation

Abstract The paper describes experimental investigations of vibrations caused by train passages in the shallow underground tunnel (in Warsaw, Poland) in comparison to the results of measurements of vibrations from ground surface transportation (trams and buses). Propagation of surface ground vibrations from underground tunnel is presented. The problem of dynamic response of a building and influence of vibrations caused by underground on people residing in a building is discussed as well. The dynamic response of the building to underground vibrations is essentially different from the response of a building excited by surface sources of transport vibrations. Also the distribution of influence of the transport vibrations on people in the building is significantly different in both cases.

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Dynamic Analysis of Tram Vehicles Coupled With the Track System Based on Staggered Iterative Algorithm

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4046822 ◽

2020 ◽

Vol 15 (6) ◽

Author(s):

Yao Shan ◽

Binglong Wang ◽

Shunhua Zhou ◽

Jiawei Zhang ◽

Aijun Huang

Keyword(s):

Dynamic Response ◽

Soft Soil ◽

Low Frequency ◽

Vehicle Body ◽

Frequency Range ◽

Fe Method ◽

Coupling System ◽

Durability Design ◽

Track System ◽

Vehicle Structure

Abstract In recent years, a large number of tram–tracks have been constructed in typical soft soil area of China. Infrastructure defects due to the differential foundation settlement are serious issues in this area. To ensure the operation safety of the tram, the influence of different infrastructure defects on the dynamic response of the tram–track system has been investigated in this paper. A dynamic model of a five-module 100% low-floor tram vehicle coupled with a slab track system is developed based on a finite element (FE) method and multibody kinematics. The articulation between different vehicle modules, the wheel–rail nonlinear contact, pad failures, and a cavity in the subgrade have been taken into account in this model. The dynamic response of the vehicle–track coupling system to different operation speeds and infrastructure defects are calculated. Results indicate that the vibration energy of the vehicle body is mainly distributed in the frequency range below 1.5 Hz. This frequency range should be paid special attention in the durability design for the vehicle structure. When the number of the failure pads is larger than 3, the pad failure in tram–track has significant influence on the system dynamic response. A cavity in subgrade has a limited effect on high frequency vibrations (above 100 Hz) of the rail, while the low frequency vibrations (below 75 Hz) of the rail can be obviously increased by cavities in subgrade. The model can be used in the optimization of suspension parameters and the tram vehicle–track coupled vibration analysis.

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Numerical investigation on dynamic response of a steel lattice tower under various seismic events

The proceedings of the 13th international conference "Modern Building Materials, Structures and Techniques" (MBMST 2019) ◽

10.3846/mbmst.2019.065 ◽

2019 ◽

Author(s):

Tomasz Falborsk ◽

Natalia Lasowicz

Keyword(s):

Dynamic Response ◽

Soil Structure ◽

Numerical Study ◽

Soft Soil ◽

Time History ◽

Time History Analysis ◽

Modal Parameters ◽

History Analysis ◽

Lattice Tower ◽

Ground Motion Records

The present paper presents the results of the numerical study designed to investigate the soil-structure flexibility effects on modal parameters (i.e. fundamental frequencies) and time-history analysis response (represented by the top relative displacements) of a 46.8 m high steel lattice tower subjected to a number of ground motions including also one mining tremor. In addition to the fixed-base condition, three different soil types (i.e. dense soil, stiff soil, and soft soil) were considered in this investigation. Site conditions were characterized by their average effective profile velocities, Poisson’s ratios, and finally mass densities. Soil-foundation flexibility was introduced using the spring-based approach, utilizing foundation springs and dashpots. The first step was to investigate the influence of different base conditions on modal parameters of the steel lattice tower. In the final part of the current study time-history analysis was performed using different two-component ground motion records (in two horizontal, mutually perpendicular directions). The results obtained indicate that modal parameters and dynamic response of the structure may be considerably affected by the soil-structure interaction effects. Therefore, the present paper confirms the necessity of utilizing soil-flexibility into numerical research.

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