Seismic response of subway station in soft soil: Shaking table testing versus numerical analysis

2020 ◽  
Vol 100 ◽  
pp. 103389 ◽  
Author(s):  
Weifeng Wu ◽  
Shiping Ge ◽  
Yong Yuan ◽  
Wenqi Ding ◽  
Ioannis Anastasopoulos
Keyword(s):  
Numerical Analysis ◽  
Seismic Response ◽  
Soft Soil ◽  
Shaking Table ◽  
Subway Station ◽  
Shaking Table Testing

Experimental Study on the Seismic Response of Subway Station in Soft Ground

2017 ◽  
Vol 11 (05) ◽  
pp. 1750020 ◽  
Author(s):  
Ma Xianfeng ◽  
Wang Guobo ◽  
Wu Jun ◽  
Ji Qianqian
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Shaking Table Test ◽  
Design Method ◽  
Underground Structure ◽  
Response Characteristic ◽  
Shaking Table ◽  
Subway Station ◽  
Soft Ground ◽  
Shaking Table Tests

Shaking table tests were conducted on typical models of subway structures subjected to several seismic shaking time histories to study seismic response of subway structures in soft ground as well as to provide data for validation of seismic design methods for underground structure. Three types of tests were presented herein, namely green field test, subway station test, and test for joint structure between subway station and tunnel. The similitude and modeling aspects of the 1g shaking table test are discussed. The seismic response of Shanghai clay in different depths was examined under different input waves to understand the acceleration amplification feature in both green field and in the presence of underground structure. Damage situation was checked on internal sections of both subway station and tunnels by halving the model structure. Structure deformation was investigated in terms of element strain under different earthquake loadings. The findings from this study provides useful pointers for future shaking table tests on underground structures/facilities, and the seismic response characteristic of underground structure derived from the shaking table test could be helpful for validating seismic design method for subway station.

scholarly journals Shaking Table Test and Numerical Verification for Free Ground Seismic Response of Saturated Soft Soil

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Xuelei Cheng ◽  
Chunyi Cui ◽  
Zongguang Sun ◽  
Jinhong Xia ◽  
Guangbing Wang
Keyword(s):  
Numerical Simulation ◽  
Seismic Response ◽  
Effective Stress ◽  
Shaking Table Test ◽  
Soft Soil ◽  
Pressure Ratio ◽  
Free Field ◽  
Shaking Table ◽  
Response Characteristics ◽  
Fully Coupled

This paper investigates shaking table test (1g) and numerical simulation (fully coupled) of vertically propagating shear waves for saturated soft free field. A large-scale shaking table model test was performed to study seismic response characteristics of saturated soft soil free field. According to test results of seismic response features of free field system in saturated soft soil, the free field nonlinearity fully coupled numerical model of dynamical effective stress of saturated soft soil was established using OpenSEES, based on the u-p formulations of dynamic consolidation equation as well as effective stress solution method for saturated two-phase media. The numerical simulation of the free field seismic response of saturated soft soil under various test conditions was performed and the calculated results were compared with the shaking table test results. The results show the following. (1) With the increase of input ground motion intensity, the characteristic frequency of the saturated soft free ground decreases and the damping ratio increases gradually. (2) The saturated soft soil ground has short period filtering and long period amplification effect on the horizontal input seismic loads. The failure foundation takes on the isolation and shock absorption under strong ground motions. (3) The peak pore pressure ratio of the saturated soft soil ground is located in the shallow buried soil layer, and with the increase of the input ground motion intensity, the advantage of dynamic pore pressure ratio in this area is gradually weakened. (4) The numerical simulation results are consistent with the results of the shaking table test. This fully coupled effective stress numerical method can reasonably simulate the seismic response characteristics of free field in saturated soft soil, which lay the foundation for other more complex parameter extrapolation models of saturated soft soil sites. This research can provide the necessary technical experience for experimental study on non-free field.

Influence of Foundation Type on Seismic Performance of Buildings Considering Soil–Structure Interaction

2016 ◽  
Vol 16 (08) ◽  
pp. 1550043 ◽  
Author(s):  
Aslan S. Hokmabadi ◽  
Behzad Fatahi
Keyword(s):  
Seismic Response ◽  
Pile Foundation ◽  
Soil Structure ◽  
Soft Soil ◽  
Shallow Foundation ◽  
Shaking Table ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Raft Foundation ◽  
Different Types

In selecting the type of foundation best suited for mid-rise buildings in high risk seismic zones, design engineers may consider that a shallow foundation, a pile foundation, or a pile-raft foundation can best carry the static and dynamic loads. However, different types of foundations behave differently during earthquakes, depending on the soil–structure interaction (SSI) where the properties of the in situ soil and type of foundation change the dynamic characteristics (natural frequency and damping) of the soil–foundation–structure system. In order to investigate the different characteristics of SSI and its influence on the seismic response of building frames, a 3D numerical model of a 15-storey full-scale (prototype) structure was simulated with four different types of foundations: (i) A fixed-based structure that excludes the SSI, (ii) a structure supported by a shallow foundation, (iii) a structure supported by a pile-raft foundation in soft soil and (iv) a structure supported by a floating (frictional) pile foundation in soft soil. Finite difference analyzes with FLAC3D were then conducted using real earthquake records that incorporated material (soil and superstructure) and geometric (uplifting, gapping and [Formula: see text] effects) nonlinearities. The 3D numerical modeling procedure had previously been verified against experimental shaking table tests conducted by the authors. The results are then presented and compared in terms of soil amplification, shear force distribution and rocking of the superstructure, including its lateral deformation and drift. The results showed that the type of foundation is a major contributor to the seismic response of buildings with SSI and should therefore be given careful consideration in order to ensure a safe and cost effective design.

scholarly journals Shaking Table Tests and Numerical Analysis on the Seismic Response of Karst-Crossing Socketed Piles in Dry Sandy Soil Foundation

2020 ◽  
Vol 15 (5) ◽  
pp. 701-709
Author(s):  
Peisen Wang ◽  
Hongyan Ding ◽  
Puyang Zhang
Keyword(s):  
Numerical Analysis ◽  
Seismic Response ◽  
Strain Distribution ◽  
Shaking Table ◽  
Karst Cave ◽  
Peak Strain ◽  
Shaking Table Tests ◽  
Karst Areas ◽  
Foundation Pile ◽  
Friction Pile

The foundation piles in karst areas have different mechanical properties from those in other areas. Targeting a critical highway bridge in a karst area, this paper designs two kinds of foundation pile models: friction pile, and KCSP, based on theories on dynamic tests. Then, shaking table tests were carried out to ascertain the features of pile strain distribution of KCSP under earthquakes. During the tests, a large laminar suspended shear box was adopted to mimic the boundary effect of soil. In addition, numerical simulations were conducted to disclose the effects of karst cave on pile strain. The test results indicate that: the peak strain of KCSP increased with the peak acceleration; For both KCSP and friction pile, the peak strain decreased first and then increased along the depth; The presence of karst cave can adversely affect the seismic response of foundation pile; The taller the karst cave, the larger the peak strain of the pile; the peak strain of KCSP was larger at the two ends, and smaller in the middle. The numerical analysis shows that: the peak strain of foundation pile in karst cave increased significantly with cave height; The peak strain of the pile passing through multiple caves was similar to that of the pile passing through only one cave, under the same cave height; But the multi-cave scenario differed from the single-cave scenario in peak strain distribution. The research results provide new insights into the seismic design of pile foundation of bridges in karst areas.

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