scholarly journals Investigation into a Homogenous Rock Slope Response Under Wide Frequency Seismic Loads Using a Large-Scale Shaking Table

2021 ◽  
Author(s):  
Jianxian He ◽  
Zhifa Zhan ◽  
Shengwen Qi ◽  
Chunlei Li ◽  
Bowen Zheng ◽  
...  
Keyword(s):  
Seismic Response ◽  
Peak Ground Acceleration ◽  
Large Scale ◽  
Rock Slope ◽  
Amplification Factor ◽  
Damping Ratio ◽  
Excitation Amplitude ◽  
Shaking Table ◽  
Ground Acceleration ◽  
Slope Structure

Abstract The main objective of this study was to investigate the effect of input earthquake characteristics on the seismic response of a homogenous step-like rock slope. A sequence of shaking table tests was performed in a large-scale physical model with a size of 3.50 m, 0.68 m and 1.20 m in length, width and height, respectively. Results showed that the absolute peak ground acceleration motion amplification factor in horizontal direction (AAF-X) of upper part of the slope was amplified comparison with that at the slope toe while the absolute peak ground acceleration motion amplification factor (AAF-Z) acquired maximum value at the lower position of the slope. With the increasing of the excitation frequencies, the AAF-X around the slope crest increased firstly and then deceased, while the AAF-Z increased continuously. Seismic response of the slope showed strongest amplification when the normalized height of the slope H/λ (ratio of slope height to wavelength) was around 0.2 and AAF-X exhibited a decrease trend when H/λ was larger than 0.2. The AAF showed nonlinear tendency with the increases of the input amplitudes, especially near the shoulder of the slope. This phenomenon can be revealed by the relationship between the calculated resonance frequency or damping ratio of the slope and the amplitude of the input motion. The excitation amplitude has a “double-effect” on the seismic response of a step-like homogeneous rock slope. That is on the one hand, the larger the excitation amplitude, the stronger the acceleration intensity, the greater deterioration of rock slope structure or material and the larger damping ratio of the slope; on the other hand, more energy will be dissipated due to plastic deformation or particle friction of high damping ratio and weaker slope structure. These results could attribute to reveal the dynamic instability mechanism of the homogeneous slope.

Composite Impulse Waves Triggered by a Combined Earthquake and Landslide

2019 ◽  
Vol 14 (01) ◽  
pp. 2050002
Author(s):  
Baoliang Wang ◽  
Lingkan Yao ◽  
Haixin Zhao ◽  
Cong Zhang
Keyword(s):  
Experimental Data ◽  
Tibetan Plateau ◽  
Peak Ground Acceleration ◽  
Large Scale ◽  
Shaking Table ◽  
The Tibetan Plateau ◽  
Impulse Wave ◽  
Effective Parameters ◽  
Ground Acceleration ◽  
Impulse Waves

Impulse waves caused by a combination of earthquakes and landslides are a neglected problem in seismic research. In the Tibetan Plateau of China, where earthquakes and landslides are frequent and glacial lakes are widely distributed, even a small lake outburst could be catastrophic. However, minimal attention has been paid to the mechanism of impulse wave formation under the joint action of earthquakes and landslides. In this study, 120 large-scale shaking table experiments were conducted to reveal the formation regularity and characteristics of an impulse wave triggered by a combined earthquake and landslide. Several effective parameters were considered: still water depth, peak ground acceleration, impact velocity, and slide volume. Based on the experimental data, an empirical formula is proposed for the superposed height of an impulse wave triggered by a combined earthquake and landslide.

scholarly journals Seismic Response of a Bridge Pile Foundation during a Shaking Table Test

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Yunxiu Dong ◽  
Zhongju Feng ◽  
Jingbin He ◽  
Huiyun Chen ◽  
Guan Jiang ◽  
...  
Keyword(s):  
Seismic Wave ◽  
Pile Foundation ◽  
Large Scale ◽  
Amplification Factor ◽  
Shaking Table Test ◽  
Seismic Intensity ◽  
Shaking Table ◽  
Acceleration Amplification ◽  
Bedrock Surface ◽  
Bridge Pile Foundation

Puqian Bridge is located in a quake-prone area in an 8-degree seismic fortification intensity zone, and the design of the peak ground motion is the highest grade worldwide. Nevertheless, the seismic design of the pile foundation has not been evaluated with regard to earthquake damage and the seismic issues of the pile foundation are particularly noticeable. We conducted a large-scale shaking table test (STT) to determine the dynamic characteristic of the bridge pile foundation. An artificial mass model was used to determine the mechanism of the bridge pile-soil interaction, and the peak ground acceleration range of 0.15 g–0.60 g (g is gravity acceleration) was selected as the input seismic intensity. The results indicated that the peak acceleration decreased from the top to the bottom of the bridge pile and the acceleration amplification factor decreased with the increase in seismic intensity. When the seismic intensity is greater than 0.50 g, the acceleration amplification factor at the top of the pile stabilizes at 1.32. The bedrock surface had a relatively small influence on the amplification of the seismic wave, whereas the overburden had a marked influence on the amplification of the seismic wave and filtering effect. Damage to the pile foundation was observed at 0.50 g seismic intensity. When the seismic intensity was greater than 0.50 g, the fundamental frequency of the pile foundation decreased slowly and tended to stabilize at 0.87 Hz. The bending moment was larger at the junction of the pile and cap, the soft-hard soil interface, and the bedrock surface, where cracks easily occurred. These positions should be focused on during the design of pile foundations in meizoseismal areas.

scholarly journals Dynamic Response of Rock Slopes under Obliquely Incident Seismic Waves

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Biao Liu ◽  
Boyan Zhang
Keyword(s):  
Dynamic Response ◽  
Peak Ground Acceleration ◽  
Rock Slope ◽  
Incident Angle ◽  
Slope Angle ◽  
Amplification Coefficient ◽  
Slope Surface ◽  
Ground Acceleration ◽  
Obliquely Incident ◽  
Acceleration Amplification

In this study, the seismic input model of slope is proposed to investigate the dynamic response of the rock slope under obliquely incident seismic wave on the basis of the time-domain wave analysis method. The model includes viscoelastic boundary considering the infinite foundation radiation damping and the seismic obliquely incident method. The semi-infinite space numerical example is simulated to verify the validity and accuracy of the model. Based on the established model, the effects of the variation of the seismic wave incident angles and slope angles on the dynamic response of a rock slope are analyzed. The results demonstrate that the changes of the incident angle and the slope angle have no discernible effect on the dynamic response of the rock slope when the P wave is obliquely incident. As the SV wave is obliquely incident, the peak ground acceleration amplification coefficient along the slope surface gradually increases with the increase of the incident angle; when the slope angle gradually increases, the peak ground acceleration amplification coefficient along the slope surface will also gradually increase at the upper part of the slope. The research results can provide some basis for the pseudostatic method to determine the seismic action coefficient.

scholarly journals Peak ground acceleration at surface for Mataram city with a return period of 2500 years using probabilistic method

2018 ◽  
Vol 195 ◽  
pp. 03019
Author(s):  
Rian Mahendra Taruna ◽  
Vrieslend Haris Banyunegoro ◽  
Gatut Daniarsyad
Keyword(s):  
Seismic Hazard ◽  
Return Period ◽  
Peak Ground Acceleration ◽  
Subduction Zones ◽  
Amplification Factor ◽  
Hazard Analysis ◽  
Probabilistic Method ◽  
Seismic Zone ◽  
Ground Acceleration ◽  
Back Arc

The Lombok region especially Mataram city, is situated in a very active seismic zone because of the existence of subduction zones and the Flores back arc thrust. Hence, the peak ground acceleration (PGA) at the surface is necessary for seismic design regulation referring to SNI 1726:2012. In this research we conduct a probabilistic seismic hazard analysis to estimate the PGA at the bedrock with a 2% probability of exceedance in 50 years corresponding to the return period of 2500 years. These results are then multiplied by the amplification factor referred from shear wave velocity at 30 m depth (Vs30) and the microtremor method. The result of the analysis may describe the seismic hazard in Mataram city which is important for building codes.

scholarly journals Microseismic Wave Measurements to Detect Landslides in Bengkulu Shore with Attenuation Coefficient and Shear Strain Indicator

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Muhammad Farid
Keyword(s):  
Shear Strain ◽  
Attenuation Coefficient ◽  
Peak Ground Acceleration ◽  
Amplification Factor ◽  
Spectral Ratio ◽  
Coastal Areas ◽  
Ratio Method ◽  
Ground Acceleration ◽  
Wave Measurements ◽  
Microseismic Data

<p>It has been detected that the condition of landslides that occurred in Bengkulu Shore can change the position of the shoreline. This research aimed to: (1) calculate of shear strain (γ) and attenuation coefficient (ά) value  based on microseismic data in coastal areas that experienced landslides; (2) determine the correlation between levels of landslides with  shear strain  and attenuation coefficient value (3) determine the correlation between the shear strain and attenuation coefficient value. Microseismic data were processed and analyzed quantitatively using the Horizontal to Vertical Spectral Ratio method (HVSR) to obtain the ground vibrations resonance frequency (<em>f<sub>o</sub></em>) and amplification factor (<em>A</em>). Shear strain value was calculated from the of <em>f<sub>o</sub></em>, <em>A</em> and Peak Ground Acceleration (<em>α<sub>max</sub></em>) value. Peak Ground Acceleration value was calculated based on 100-year period of recorded earthquake data.  Attenuation coefficient was calculated based on the equation (2). The results of study showed that the value of shear strain in the coastal areas varied from 1.0 × 10<sup>-4</sup> to 3.6 × 10<sup>-3</sup>,  in accordance with the conditions of landslides. The attenuation coefficient value varied from 0.005 to 0.020.  Level of landslides that occurred varied from moderate, to very severe. There was a tendency that the more severe the landslide level,  the greater the shear strain and attenuation coefficient value were.</p>

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