• Geomechanics and Engineering
• /
• 제11권6호
• /
• pp.821-845
• /
• 2016

Extensive researches on distribution of earthquake induced damages in different regions have shown that geological and geotechnical conditions of the local soils significantly influence behavior of alluvial areas under seismic loading. In this article, the site of Babol city which is formed up of saturated fine alluvial soils is considered as a case study. In order to reduce the uncertainties associated with earthquake resistant design of structures in this area (Babol city), the required design parameters have been evaluated with consideration of site's dynamic effects. The utilized methodology combines experimental ground ambient noise analysis, expressed in terms of horizontal to vertical (H/V) spectral ratio, with numerical one-dimensional response analysis of soil columns using DEEPSOIL software. The H/V spectral analysis was performed at 60 points, experimentally, for the region in order to estimate both the fundamental period and its corresponding amplification for the ground vibration. The investigation resulted in amplification ratios that were greater than one in all areas. A good agreement between the proposed ranges of natural periods and alluvial amplification ratios obtained through the analytical model and the experimental microtremor studies verifies the analytical model to provide a good engineering reflection of the subterraneous alluviums.

• Geomechanics and Engineering
• /
• 제31권4호
• /
• pp.423-437
• /
• 2022

The objective of the study is to evaluate the feasibility of the dynamic behavior of slope through both 1 g shaking table test and numerical analysis. Accelerometers were installed in the slope model with different types of seismic waves. The numerical analysis (ABAQUS and DEEPSOIL) was used to simulate 1 g shaking table test at infinite boundary. Similar Acceleration-time history, Spectral acceleration (SA) and Spectral acceleration amplification factor (Fa) were obtained, which verified the feasibility of modeling using ABAQUS and DEEPSOIL under the same size. The influence of the size (1, 2, 5, 10 and 20 times larger than that used in the 1 g shaking table test) of the model used in the numerical analysis were extensively investigated. According to the similitude law, ABAQUS was used to analyze the dynamic behavior of large-scale slope model. The 5% Damping Spectral acceleration (SA) and Spectral acceleration amplification factor (Fa) at the same proportional positions were compared. Based on the comparison of numerical analyses and 1 g shaking table tests, it was found that the 1 g shaking table test result can be utilized to predict the dynamic behavior of the real scale slope through numerical analysis.

• 지질공학
• /
• 제32권1호
• /
• pp.143-155
• /
• 2022

본 연구에서는 지진 모사실험을 진행하는 1 g 진동대 실험에 올라가는 연성토조(Laminar Shear Box, LSB)라고 하는 토조의 경계조건(Boundary effect)을 달리하여 다른 조건에 따른 응답가속도 증폭에 대한 분석하였다. LSB의 양 옆을 고정하여 경계조건을 달리하여 실험을 진행하였고, 가속도계를 각 동일한 위치에 설치하여 2가지 시료에 대하여 실험을 진행하였다. 또한, DEEPSOIL v7 프로그램을 이용하여 1차원 지반응답해석을 통하여 자유장 조건에서와 비교 분석하였다. 그 결과 가속도가 하층부에서 상층부로 올라갈수록 증폭하는 모습을 확인할 수 있었고, 지반응답해석과 비교한 결과, 자유장 조건에서 해석과 비슷하게 나오는 것을 확인할 수 있었다. SA분석결과, 지반응답해석과 유사한 결과를 얻을 수 있었으며, 고정한 경우는 PSA가 더욱 증폭하는 결과를 확인할 수 있었다.

• Geomechanics and Engineering
• /
• 제8권5호
• /
• pp.663-674
• /
• 2015

Many seismically vulnerable regions in India and worldwide are located on deep soil deposits which extend to several hundred meters of depth. It has been well recognized that the earthquake shaking is altered by geological conditions at the location of building. As seismic waves propagates through uppermost layers of soil and rock, these layers serve as filter and they can increase the duration and amplitude of earthquake motion within narrow frequency bands. The amplification of these waves is largely controlled by mechanical properties of these layers, which are function of their stiffness and damping. Stiffness and damping are further influenced by soil type and thickness. In the current study, an attempt has been made to study the seismic site response of deep soils. Three hypothetical homogeneous soil models (e.g., soft soil, medium soil and hard soil) lying on bedrock are considered. Depth of half space is varied from 30 m to 2,000 m in this study. Controlled synthetic motions are used as input base motion. One dimensional equivalent linear ground response analyses are carried out using a computer package DEEPSOIL. Conventional approach of analysing up to 30 m depth has been found to be inadequate for deep soil sites. PGA values are observed to be higher for deeper soil profiles as compared to shallow soil profiles indicating that deeper soil profiles are more prone to liquefaction and other related seismic hazards under earthquake ground shaking. The study recommends to deal the deeper soil sections more carefully for estimating the amplification factors for seismic hazard assessment at the surface.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제13권6호
• /
• pp.31-39
• /
• 2008

본 연구는 전국 및 경기도에서 수행한 토양오염실태조사를 평가하고 그 효율성을 제고하기 위하여 수행하였다. 2002년${\sim}$2007년 동안 경기도 및 전국의 실태조사결과 오염발견율은 전국이 2.7%, 경기도가 평균 1.9%를 나타내 일본, 미국에 비해 낮은 발견율을 나타내었다. 또한 전국의 중금속과 석유류 기준초과물질 구성 비율이 89.8%와 8.9%였는데, 이는 중금속을 대상으로 하는 표토 조사대상이 38%인 점과 석유류를 대상으로 하는 심토의 조사비중이 62%를 나타낸 것과 모순된 현상으로 심토에 대한 조사방법의 개선이 요구된다. 오염 발견율에 영향을 미치는 요소로 지점선정단계, 시료채취단계, 시료분석단계를 들 수 있으며 이중 가장 중요한 지점선정단계에 있어서 우선순위선정을 위한 방침을 제시하였다. 부연하여 사후관리를 위한 방안으로 녹색업체 부여 등의 인증 제도를 건의하였다.