The slope seismic response monitoring of Wenchuan aftershocks in Qingchuan

Abstract. This work reports some new progress of rock slope inside seismic response monitoring results in the area of Mountain Dong and Mountain Shizi (Qingchuan county), located more than 250 km NE of Yingxiu epicenter (2008 Wenchuan earthquake), Sichuan province. Five adits with the maximum depth of 15 m had been excavated in different elevation on both sides slope. Stations were emplaced at middle of the adits, from September 2009 to May 2010 more than 60 Wenchuan aftershocks had been monitored, 22 typical aftershocks had been analysis, whose magnitude varied between 2.3 ~ 5.2 and epicentral distance was from a few to 45 km. A comparison analysis of recordings provided evidence of the presence amplification effect at the Q4 station of Mt. Dong, which the peak horizontal acceleration amplification factor is between 1.0 ~ 2.5. But this amplification effect had no stronger at other stations. Comprehensive studies show that the relative height to riverbed is an important factor of Q4 seismic amplification effect. Otherwise the topography of Q4 site is conducive to horizontal amplification, not the vertical amplification. Moreover the calculation of Arias intensity (Ia) had the same amplification effect as the PGA, only the amplification factor is between 1.0 ~ 3.47 much bigger than the latter. On the other hand, the calculation of horizontal to vertical spectral ratio (HVSR) at Q4 shows the curves have multiple peaks corresponding with different dominant frequencies, which the amplification factor is always bigger than other stations at Mt. Dong. Sufficient evidence indicates that the Mt. Dong amplification effect is stronger than Mt. Shizi.

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Numerical Analysis of the Seismic Response of Tunnel Composite Lining Structures across an Active Fault

Advances in Materials Science and Engineering ◽

10.1155/2021/1518763 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Zude Ding ◽

Mingrong Liao ◽

Nanrun Xiao ◽

Xiaoqin Li

Keyword(s):

Seismic Response ◽

Fault Zone ◽

Composite Structure ◽

Composite Structures ◽

Seismic Waves ◽

Distribution Area ◽

Damage Degree ◽

Acceleration Amplification ◽

Lining Structure ◽

Composite Lining

The mechanical properties of high-toughness engineering cementitious composites (ECC) were tested, and a damage constitutive model of the materials was constructed. A new aseismic composite structure was then built on the basis of this model by combining aseismic joints, damping layers, traditional reinforced concrete linings, and ECC linings. A series of 3D dynamic-response numerical models considering the composite structure-surrounding rock-fault interaction were established to explore the seismic response characteristics and aseismic performance of the composite structures. The adaptability of the structures to the seismic intensity and direction was also discussed. Results showed that the ECC material displays excellent tensile and compressive toughness, with respective peak tensile and compressive strains of approximately 300- and 3-fold greater than those of ordinary concrete at the same strength grade. The seismic response law of the new composite lining structure was similar to that of the conventional composite structure. The lining in the fault zone and adjacent area showed obvious acceleration amplification responses, and the stress and displacement responses were fairly large. The lining in the fault zone was the weak part of the composite structures. Compared with the conventional aseismic composite structure, the new composite lining structure effectively reduced the acceleration amplification and displacement responses in the fault area. The damage degree of the new composite structure was notably reduced and the damage area was smaller compared with those of the conventional composite structure; these findings demonstrate that the former shows better aseismic effects than the latter. The intensity and direction of seismic waves influenced the damage of the composite structures to some extent, and the applicability of the new composite structure to lateral seismic waves is significantly better than that to axial waves. More importantly, under the action of different seismic intensities and directions, the damage degree and distribution area of the new composite structure were significantly smaller than those of the conventional composite lining structure.

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A Method to Directly Estimate S-Wave Site Amplification Factor from Horizontal-to-Vertical Spectral Ratio of Earthquakes (eHVSRs)

Bulletin of the Seismological Society of America ◽

10.1785/0120190315 ◽

2020 ◽

Vol 110 (6) ◽

pp. 2892-2911

Author(s):

Eri Ito ◽

Kenichi Nakano ◽

Fumiaki Nagashima ◽

Hiroshi Kawase

Keyword(s):

Amplification Factor ◽

Strong Motion ◽

Spectral Ratio ◽

Site Amplification ◽

Body Waves ◽

Correction Function ◽

Site Classification ◽

Frequency Range ◽

S Wave ◽

Site Amplification Factor

ABSTRACT The main purpose of the site classification or velocity determination at a target site is to obtain or estimate the horizontal site amplification factor (HSAF) at that site during future earthquakes because HSAF would have significant effects on the strong-motion characteristics. We have been investigating various kinds of methods to delineate the S-wave velocity structures and the subsequent HSAF, as precisely as possible. After the advent of the diffuse field concept, we have derived a simple formula based on the equipartitioned energy density observed in the layered half-space for incident body waves. In this study, based on the diffuse field concept, together with the generalized spectral inversion technique (GIT), we propose a method to directly estimate the HSAF of the S-wave portion from the horizontal-to-vertical spectral ratio of earthquakes (eHVSRs). Because the vertical amplification is included in the denominator of eHVSR, it cannot be viewed as HSAF without correction. We used GIT to determine both the HSAF and the vertical site amplification factor (VSAF) simultaneously from strong-motion data observed by the networks in Japan and then deduced the log-averaged vertical amplification correction function (VACF) from VSAFs at a total of 1678 sites in which 10 or more earthquakes have been observed. The VACF without a category has a constant amplitude of about 2 in the frequency range from 1 to 15 Hz. By multiplying eHVSR by VACF, we obtained the simulated HSAF. We verified the effectiveness of this correction method using data from observation sites not used in the aforementioned averaging in the frequency range from 0.12 to 15 Hz.

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

Shock and Vibration ◽

10.1155/2019/9726013 ◽

2019 ◽

Vol 2019 ◽

pp. 1-16 ◽

Cited By ~ 1

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.

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Assessment of seismic amplification factor of excavation with support system

Earthquake Engineering and Engineering Vibration ◽

10.1007/s11803-019-0521-x ◽

2019 ◽

Vol 18 (3) ◽

pp. 555-566 ◽

Cited By ~ 2

Author(s):

Hamidreza Tavakoli ◽

Saman Soleimani Kutanaei ◽

Seyed Hossein Hosseini

Keyword(s):

Support System ◽

Amplification Factor ◽

Seismic Amplification

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Stiffness Design for Specified Nonexceedance Probability of Seismic Response

Earthquake Spectra ◽

10.1193/1.1585994 ◽

1998 ◽

Vol 14 (1) ◽

pp. 165-188 ◽

Cited By ~ 3

Author(s):

Yutaka Nakamura ◽

Tsuneyoshi Nakamura

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Seismic Response ◽

Amplification Factor ◽

Design Method ◽

Response Spectrum ◽

Time History ◽

Stiffness Design ◽

The Mean ◽

Shear Building

A direct procedure is presented for generating a response spectrum for an arbitrary nonexceedance probability from a prescribed design mean response spectrum. An amplification factor is derived to estimate the maximum response values of an MDOF system for a nonexceedance probability from the mean maximum ones. An efficient stiffness design method for a shear building is developed with the use of its fundamental frequency and translational eigenvector as parameters for adjusting the nonexceedance probability of the seismic drifts to the specified value. The validity and accuracy of the proposed method are demonstrated by a Monte Carlo simulation together with time-history analyses.

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A novel numerical modelling of well-aquifer response induced by pressure disturbance

10.5194/egusphere-egu2020-7004 ◽

2020 ◽

Author(s):

Yixuan Xing ◽

Rui Hu ◽

Hongbiao Gu ◽

Quan Liu ◽

Thomas Ptak

Keyword(s):

Water Level ◽

Water Column ◽

Amplification Factor ◽

Fluid Model ◽

Pressure Head ◽

Column Height ◽

Screen Length ◽

Amplification Effect ◽

Aquifer Properties ◽

Water Column Height

Under hydrostatic conditions, the water level observed in a well is often supposed to be equivalent to the pressure head in the surrounding aquifer. When the aquifer is subject to disturbing processes and activities, fluctuations of water level can be observed. Generally, the measured water level in the well is often considered to be less than the pressure head in the aquifer due to wellbore storage and skin effects (Ramey et al., 1972). In fact, there is another factor that can suppress or enhance the oscillating water level, which is termed the amplification effect (Cooper et al., 1965). Related studies point out that this effect is affected by well geometry (e.g. well diameter, water column height and well screen length), aquifer properties (e.g. transmissivity and storativity) and the period of the disturbed pressure head (Kipp, 1985; Liu, 1989). However, previous studies have obvious divergences in quantifying the amplification effect.In this work, we firstly established an idealized fluid model to simplify the complex solid-fluid coupling process, aiming to discuss the influence of different well geometry parameters on the amplification factor separately, such as the well diameter, water column height and well screen length. Subsequently, we built a well-aquifer coupling numerical model to study the well-aquifer response induced by disturbed pressure based on the finite element method. Simulations of 125 scenarios showed that the amplification factor gradually increased until it reached a peak, and then decreased to 1 as the period of disturbed pressure became larger. The corresponding period of an amplification factor peak was significantly influenced by the water column height, which controlled the position of an &#8220;optimal period&#8221;. Aquifer properties can also affect the amplification factor, especially its peak value. In further numerical studies, more complicated scenarios will be investigated, considering different types of wells and aquifers.

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Empirical Spectral Acceleration Amplification in the Iwate-Miyagi and Niigata Regions, Japan, Inferred by a Spectral Ratio Method Using Ground-Motion Prediction Equations

Bulletin of the Seismological Society of America ◽

10.1785/0120130124 ◽

2014 ◽

Vol 104 (3) ◽

pp. 1410-1429 ◽

Cited By ~ 3

Author(s):

R. Ibrahim ◽

H. Si ◽

K. Koketsu ◽

H. Miyake

Keyword(s):

Ground Motion ◽

Spectral Ratio ◽

Ratio Method ◽

Motion Prediction ◽

Spectral Acceleration ◽

Ground Motion Prediction Equations ◽

Prediction Equations ◽

Ground Motion Prediction ◽

Acceleration Amplification ◽

Spectral Ratio Method

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Least Feasible Seismic Response of the Secondary Appendage System : Analysis Using Floor Response Amplification Factor

Transactions of the Japan Society of Mechanical Engineers ◽

10.1299/kikai1938.44.3749 ◽

1978 ◽

Vol 44 (387) ◽

pp. 3749-3758 ◽

Cited By ~ 3

Author(s):

Kohei SUZUKI ◽

Shigeru AOKI

Keyword(s):

Seismic Response ◽

System Analysis ◽

Amplification Factor ◽

Response Amplification

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Microzonation of Cisarua District Using Horizontal Vertical Spectral Ratio

Jurnal Ilmu dan Inovasi Fisika ◽

10.24198/jiif.v5i2.31533 ◽

2021 ◽

Vol 5 (2) ◽

pp. 88-94

Author(s):

Elrangga Ibrahim Fattah ◽

Keyword(s):

Amplification Factor ◽

Active Faults ◽

Spectral Ratio ◽

Dominant Frequency ◽

Research Area ◽

Geological Structure ◽

Eurasian Plate ◽

Hvsr Method ◽

Microtremor Measurement ◽

Tectonic System

The Bandung region is part of the framework of the Indonesian tectonic system, namely the tectonic plate meeting zone, where the Indo Autralia plate is infiltrated under the Eurasian plate in a convergent manner. The subduction process produces an effect in the form of an active fault geological structure in the Bandung area. One of these active faults is the Lembang Fault, which has a length of ± 29 kilometers and a shear acceleration of 3 to 5.5 millimeters per year. The microtremor measurement method is a passive geophysical method that utilizes natural subsurface vibrations so that it can provide dominant frequency data and amplification factors for soil layers. Based on the results of seismic susceptibility research using microtremor measurements using the HVSR method in the Lembang Fault zone in Cisarua Sub-District, it can be seen that the distribution of the dominant frequency values tends to be influenced by lithology and topography. In the research area, it is known to have a dominant frequency value that varies due to the different types of lithological units. In general, the dominant frequency ranges from 1-3 Hz because it is dominated by tuff sand and tuff pumice, and areas composed of volcanic breccias have a dominant frequency value between 3-6 Hz. Meanwhile, the amplification factor value will be influenced by rock deformation and weathering. The area that has a very high amplification factor value is in the southeast of the study area with an A0 value greater than 5. This indicates that the area is composed of a layer of thick and not dense tuff sand

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

KnE Engineering ◽

10.18502/keg.v0i0.477 ◽

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

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 (fo) and amplification factor (A). Shear strain value was calculated from the of fo, A and Peak Ground Acceleration (αmax) 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 × 10-4 to 3.6 × 10-3, 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.

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