• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.3
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• pp.55-63
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• 2015

Embankment of agricultural reservoir started by four major rivers project. Most agricultural reservoirs must insure the agricultural water, they need must be ensured stability of embankment. Recently, there is a growing interest in seismic stability of structure by earthquake. Results of evaluation of the structural stability through seismic vibration test and numerical analysis, maximum displacement and the maximum acceleration is a similar trends. Appeared by increasing occurrence of the value of the displacement and acceleration of the structure with the result long period wave type in accordance with the seismic wave in the case of seismic waves, which shows the results of similar tendency as long period wave type consists of waveform seismic acceleration. Model test and numerical analysis results with in order to increase embankment agricultural reservoir, the displacement was found to ensure it is displayed within one percentage structural stability of the embankment.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.64-74
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• 2016

Recently, the seismic stability evaluation of concrete gravity dams is raised due to the failure of dams occurred by the Izmit, Turkey and JiJi, Taiwan earthquake in 1999. Dams failure may incur loss of life and properties around the dam as well as damage to dam structure itself. Recently, there has been growing much concerns about "earthquake - resistance" or "seismic safety" of existing concrete gravity dams designed before current seismic design provisions were implemented. This research develops three evaluation levels for seismic stability of concrete gravity dams on the basis of the evaluation method of seismic stability of concrete gravity dams in U.S.A., Japan, Canada, and etc. Level 1 is a preliminary evaluation which is for purpose of screening. Level 2 is a pseudo-static evaluation on the basis of the seismic intensity method. And level 3 is a detail evaluation by the dynamic analysis. Evaluation results on existing concrete gravity dams on operation showed good seismic performance under designed artificial earthquake(KHC earthquake).

• Geomechanics and Engineering
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• v.23 no.1
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• pp.1-13
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• 2020

To give a solution for seismic stability of tunnel faces subjected to earthquake ground shakings, the pseudo-dynamic approach is originally introduced to analyze tunnel face stability in this study. In the light of the upper-bound theorem of limit analysis, an advanced three-dimensional mechanism combined with pseudo-dynamic approach is proposed. Based on this mechanism, the required support pressure on tunnel face can be obtained by equaling external work rates to the internal energy dissipation and implementing an optimization searching procedure related to time. Both time and space feature of seismic waves are properly accounted for in the proposed mechanism. For this reason, the proposed mechanism can better represent the actual influence of seismic motion and has a remarkable advantage in evaluating the effects of vertical seismic acceleration, soil amplification factor, seismic wave period and initial phase difference on tunnel face stability. Furthermore, the pseudo-dynamic approach is compared with the pseudo-static approach. The difference between them is illustrated from a new but understandable perspective. The comparison demonstrates that the pseudo-static approach is a conservative method but still could provide precise enough results as the pseudo-dynamic approach if the value of seismic wavelengths is large or the height of soil structures is small.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.653-659
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• 2020

In this study, seismic verification of the bellows used in the plant field was conducted. The pressure used in the analysis was analyzed by applying the design pressure of 15.7bar. For the seismic analysis, the natural frequency of the bellows system was obtained and the stability of the system was evaluated by static seismic analysis comparing the lowest order natural frequency with the dominant frequency of 33 Hz. The material of the bellows system is STS304, and the safety factor is obtained in comparison with the allowable stress. For the seismic analysis, the design response spectrum was prepared and the maximum acceleration was applied to the static seismic analysis and the stability of the entire system was confirmed. Compared to the structural analysis results, the maximum stress of the bellows system increased by about 16.4% and the maximum strain increased by about 3 times when seismic analysis was performed.

• Journal of the Korean Geotechnical Society
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• v.26 no.3
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• pp.47-57
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• 2010

Yield seismic coefficient plays an important role in the estimation of permanent displacement of a soil slope subjected to earthquake using Newmark's sliding block theory. However, yield seismic coefficients currently used in practices are not mechanically rigorous since most of them are estimated using limit equilibrium methods considering equilibrium condition only. Therefore, estimation of permanent displacement of a soil slope based on existing yield seismic coefficient may cause problems. Limit analysis estimating the range of mechanically rigorous solution is thought to be effective in evaluating the validity of existing yield seismic coefficient. In this study, a simple stability chart for yield seismic coefficient useful in practices is proposed by considering various slope conditions including stability number, slope inclination, strength parameters, etc.

• Geomechanics and Engineering
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• v.29 no.6
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• pp.599-614
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• 2022

In this study, the reliability analysis of internal and external stabilities of Reinforced Soil Walls (RSWs) under static and seismic loads are investigated so that it can help the geotechnical engineers to perform the design more realistically. The effect of various variables such as angle of internal soil friction, soil specific gravity, tensile strength of the reinforcements, base friction, surcharge load and finally horizontal earthquake acceleration are examined assuming the variables uncertainties. Also, the correlation coefficient impact between variables, sensitivity analysis, mean change, coefficient of variation and type of probability distribution function were evaluated. In this research, external stability (sliding, overturning and bearing capacity) and internal stability (tensile rupture and pull out) in both static and seismic conditions were investigated. Results of this study indicated sliding as the predominant failure mode in the external stability and reinforcing rupture in the internal stability. First-Order Reliability Method (FORM) are applied to estimate the reliability index (or failure probability) and results are validated using the Monte Carlo Simulation (MCS) method. The results showed among all variables, the internal friction angle and horizontal earthquake acceleration have dominant impact on the both reinforced soil wall internal and external stabilities limit states. Also, the type of probability distribution function affects the reliability index significantly and coefficient of variation of internal friction angle has the greatest influence in the static and seismic limits states compared to the other variables.

• Earthquakes and Structures
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• v.7 no.6
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• pp.1187-1221
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• 2014

The uplifting and rocking of slender, free-standing structures when subjected to ground shaking may limit appreciably the seismic moments and shears that develop at their base. This high-performance seismic behavior is inherent in the design of ancient temples with emblematic peristyles that consist of slender, free-standing columns which support freely heavy epistyles together with the even heavier frieze atop. While the ample seismic performance of rocking isolation has been documented with the through-the-centuries survival of several free-standing ancient temples; and careful post-earthquake observations in Japan during the 1940's suggested that the increasing size of slender free-standing tombstones enhances their seismic stability; it was George Housner who 50 years ago elucidated a size-frequency scale effect that explained the "counter intuitive" seismic stability of tall, slender rocking structures. Housner's 1963 seminal paper marks the beginning of a series of systematic studies on the dynamic response and stability of rocking structures which gradually led to the development of rocking isolation-an attractive practical alternative for the seismic protection of tall, slender structures. This paper builds upon selected contributions published during this last half-century in an effort to bring forward the major advances together with the unique advantages of rocking isolation. The paper concludes that the concept of rocking isolation by intentionally designing a hinging mechanism that its seismic resistance originates primarily from the mobilization of the rotational inertia of its members is a unique seismic protection strategy for large, slender structures not just at the limit-state but also at the operational state.

• Tunnel and Underground Space
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• v.19 no.3
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• pp.174-180
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• 2009

This paper gives a brief review of seismicity and seismic monitoring in surface mines. A summary of various researches related to seismicity is presented. Our research focuses on the understanding of seismicity and the application of analytical techniques to seismicity. Seismic monitoring plays an important role in the identification of potential failure planes and thereby predict potential failures. Much of the instrumentation used in our research is derived from earthquake monitoring systems. The major aspects in seismic monitoring are an instrumentation used, size of the network and data acquisition systems. Seismic monitoring in surface mines could be successfully applied to the improvement of safety standards in slope stability.

• Structural Monitoring and Maintenance
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• v.7 no.4
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• pp.295-317
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• 2020

Investigation of the stability of arch dam abutments is one of the most important aspects in the analysis of this type of dams. To this end, the Bakhtiari dam, a doubly curved arch dam having six wedges at each of its abutments, is selected. The seismic safety of dam abutments is studied through time history analysis using the design-based earthquake (DBE) and maximum credible earthquake (MCE) hazard levels. Londe limit equilibrium method is used to calculate the stability of wedges in abutments. The thrust forces are obtained using ABAQUS, and stability of wedges is calculated using the code written within MATLAB. Effects of foundation flexibility, grout curtain performance, vertical component of earthquake, nonlinear behavior of materials, and geometrical nonlinearity on the safety factor of the abutments are scrutinized. The results show that the grout curtain performance is the main affecting factor on the stability of the abutments, while nonlinear behavior of the materials is the least affecting factor amongst others. Also, it is resulted that increasing number of the contraction joints can improve the seismic stability of dam. A cap is observed on the number of joints, above which the safety factor does not change incredibly.

• Geomechanics and Engineering
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• v.11 no.4
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• pp.457-469
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• 2016

Steep rock slope with water-filled tension crack will happen to overturn around the toe of the slope under seismic loading. This failure type is completely different from the common toppling failure occurring in anti-dipping layered rock mass slopes with steeply dipping discontinuities. This paper presents an analytical approach to determine the seismic factor of safety against overturning for an intact rock mass slope with water-filled tension crack considering horizontal and vertical seismic coefficients. This solution is a generalized explicit expression and is derived using the moment equilibrium approach. A numerical program based on discontinuous deformation analysis (DDA) is adopted to validate the analytical results. The parametric study is carried out to adequately investigate the effect of horizontal and vertical seismic coefficients on the overall stability against overturning for a saturated rock slope under two water pressure modes. The analytical results show that vertically upward seismic inertia force or/and second water pressure distribution mode will remarkably decrease the slope stability against overturning. Finally, several representative design charts of slopes also are presented for the practical application.