• Journal of Industrial Technology
• /
• v.28 no.B
• /
• pp.39-45
• /
• 2008

Temperature variation according to space and time on the inner parts of engineering constructions(e.g.: dam, slope) can be a basic information for diagnosing their safety problem. In general, as constructions become superannuated, structural deformation(e.g.: cracks, defects) could be occurred by various factors. Seepage or leakage of water through these cracks or defects in old dams will directly cause temperature anomaly. Groundwater level also can be easily observed by abrupt change of temperature on the level. This study shows that the position of seepage or leakage in dam body can be detected by multi-channel temperature monitoring using thermal line sensor. For this, diverse temperature monitoring experiments for a leakage physical model were performed in the laboratory. In field application of an old earth fill dam, temperature variations for water depth and for inner parts of boreholes located at downstream slope were measured. Temperature monitoring results for a long time at the bottom of downstream slope of the dam showed the possibility that temperature monitoring can provide the synthetic information about flowing path and quantity of seepage of leakage in dam body.

• Journal of Environmental Science International
• /
• v.31 no.6
• /
• pp.461-470
• /
• 2022

When an agricultural soil dam collapses, the extent of inundation and the rate of diffusion vary depending on where the collapse occurs in the dam body. In this study, a dam collapse scenario was established and a two-dimensional numerical model FLO-2D was used to closely examine the inundation pattern of the downstream residential area according to the dam collapse point. The results were presented as a flood risk map showing the changes and patterns of the extent of inundation spread. The flood level and the time to reach the maximum water level vary depending on the point of collapse, and the inundation of the downstream area proceeds rapidly in the order of the midpoint, left point, and right point collapse. In the left collapse point, the submergence appeared about 0.5 hour slower than the middle point, and the right collapse point appeared about 1 hour slower than the middle point. Since the relative damage pattern is different depending on the dam collapse point, insurance and disaster countermeasures will have to be established differently.

• Earthquakes and Structures
• /
• v.26 no.1
• /
• pp.59-75
• /
• 2024

This paper presents a dam-reservoir interaction model that includes, water compressibility, sloshing of surface water, and radiation damping at the far-end reservoir, to investigate the influence of concrete deterioration on seismic behavior along with seismic performance of gravity dams. Investigations on seismic performance of the dam body have been conducted using the linear time-history responses obtained under six real and 0.3 g normalized earthquake records with time durations from 10 sec to 80 sec. The deterioration of concrete is assumed to develop due to mechanical and chemical actions over the dam lifespan. Several computer programs have been developed in FORTRAN 90 and MATLAB programming languages to analyze the coupled problem considering two-dimensional (2D) plane-strain condition. According to the results obtained from this study, the dam structure shows critical responses at the later ages (75 years) that could cause disastrous consequences; the critical effects of some earthquake loads such as Chi-Chi with 36.5% damage and Loma with 56.2% damage at the later ages of the selected dam body cannot be negligible; and therefore, the deterioration of concrete along with its effects on the dam response should be considered in analysis and design.

• Journal of the Korean Geosynthetics Society
• /
• v.20 no.1
• /
• pp.45-55
• /
• 2021

In this study, the behavioral characteristics of the fill dam were analyzed during water level fluctuations through a numerical analysis model, and the reservoir safety management plan was prepared. The variation in plastic deviatoric strain, horizontal displacement, stress path, pore water pressure, etc., due to elevation of water level in the upper and lower sides of shell and core were analyzed using numerical analysis software, viz. GTS NX and LIQCA. The analysis results manifest that as the water level in the dam body increases rapidly, the pore water pressure and displacement also increase quickly. It was found that the elevation of the water level causes an increase in pore water pressure in the dam body as well as an increase in the saturation of the dam body and decreased effective stress. It is considered that this type of dam behavior can be the cause of the reduction of strength and stiffness of the dam. Also, it is assumed that the accumulated plastic deviatoric strain due to the deformation of the dam body caused by water infiltration causes an increase in displacement. Based on these experimental results and the results of analyses of the existing reservoir safety diagnosis techniques, an improvement plan for dam safety diagnosis and evaluation criteria was proposed, and these results can be used as primary data while revising dam safety diagnosis guidelines.

• Structural Engineering and Mechanics
• /
• v.57 no.3
• /
• pp.529-541
• /
• 2016

Under the interaction between dam body, dam foundation and external environment, the dam structural behavior presents the time-varying nonlinear characteristics. According to the prototypical observations, the correct identification on above nonlinear characteristics is very important for dam safety control. It is difficult to implement the description, analysis and diagnosis for dam structural behavior by use of any linear method. Based on the rescaled range analysis approach, the algorithm is proposed to identify and extract the fractal feature on observed dam structural behavior. The displacement behavior of one actual dam is taken as an example. The fractal long-range correlation for observed displacement behavior is analyzed and revealed. The feasibility and validity of the proposed method is verified. It is indicated that the mechanism evidence can be provided for the prediction and diagnosis of dam structural behavior by using the fractal identification method. The proposed approach has a high potential for other similar applications.

• Structural Monitoring and Maintenance
• /
• v.6 no.4
• /
• pp.347-364
• /
• 2019

Two seismic response data from the CSMIP strong motion instrumentation of Pacoima dam are selected: San Fernando earthquake (Jan 13, 2001; ML=4.3) and Newhall earthquake (Sept. 1, 2011; ML=4.2), for the identification of the dam system. To consider the spatially nonuniform input ground motion along the dam abutment, the subspace identification technique with multiple-input and multiple-output is used to extract the dynamic behavior of the dam-reservoir interaction system. It is observed that the dam-reservoir interaction is significant from the identification of San Fernando earthquake data. The influence of added mass (from the reservoir) during strong ground motion will create a tuned-mass damper phenomenon on the dam body. The fundamental frequency of the dam will be tuned to two different frequencies but with the same mode shapes. As for the small earthquake event, the dam-reservoir interaction is insignificant.

• Smart Structures and Systems
• /
• v.26 no.3
• /
• pp.319-329
• /
• 2020

Structural damage to an arch dam is often of major concern and must be evaluated for probable rehabilitation to ensure safe, regular, normal operation. This evaluation is crucial to prevent any catastrophic or failure consequences for the life time of the dam. If specific major damage such as a large crack occurs to the dam body, the assessments will be necessary to determine the current level of safety and predict the resistance of the structure to various future loading such as earthquakes, etc. This study investigates the behavior of an arch dam cracked due to water pressure. Safety factors (SFs), of shear and compressive tractions were calculated at the surfaces of the contraction joints and the cracks. The results indicated that for cracking with an extension depth of half the thickness of the dam body, for both cases of penetration and non-penetration of water load into the cracks, SFs only slightly reduces. However, in case of increasing the depth of crack extension into the entire thickness of the dam body, the friction angle of the cracked surface is crucial; however, if it reduces, the normal loading SFs of stresses and joints tractions reduce significantly.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.3 no.1
• /
• pp.123-132
• /
• 1999

One of the major difficulties in the seismic analysis of a dam-reservoir system is the treatment of the energy radiation in the upstream direction of the reservoir. In the paper, a new transmitting boundary is presented that can model properly the radiation of energy in the far field direction of a semi-infinite reservoir with constant depth. In the newly developed method, effects of surface wave motion are taken into accounted and the reservoir-foundation interaction is approximately accounted for with an absorbing boundary condition. If a dam has vertical upstream face and the infinitely long reservoir maintains constant depth, then the proposed transmitting boundary can be directly coupled with the model of dam body. In present study, the dam body is assumed to behave elastically and modeled by finite element method. Seismic responses of a dam model are investigated using the newly developed transmitting boundary.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1999.04a
• /
• pp.267-274
• /
• 1999

Since the seismic response of dams can be strongly influenced by the dam-reservior interaction in needs to be taken into account in the seismic design of dams. In general a substructure method is employed to solve the dam-reservoir interaction problem in which the dam body is modeled with finite elements and the infinite region of a reservoir using a transmitting boundary. When the water is modeled as a compressible fluid the equation is formulated in frequency domain. But nonlinear behavior of dam body cannot be studied easily in the frequency domain method. In this study time domain formulation of the dam-reservoir-soil interaction is proposed based onthe lumped parameter modeling of the reservoir region, The frequency dependent dynamic-stiffness coefficients of the reservoir are converted into frequency independent lumped-parameters such as masses dampers and springs. The soil-structure interactionis modeled using lumped parameters in similar way. the ground is assumed as a visco-elastic stratum on the rigid bedrock. The dynamic stiffnesses of the rigid surface foundation are calculated using the hyperelement method and are converted into lumped parameters. The application example demonstrated that the lumped parameter model gives almost identical results with the frequency domain formulation.

• Journal of Acupuncture Research
• /
• v.30 no.4
• /
• pp.55-68
• /
• 2013

Objectives : The purpose of this study is to analyze the distribution, relationship, prognosis and improvement score of idiopathic facial palsy inpatients according to constitutional differentiation ; Sasang constition, Hyungsang classification, Sasang constition combined with Hyungsang classification. Methods : A study was done on 102 patients who were diagnosed and treated as idiopathic facial palsy from April 2012 to Nomember 2012 at the Department of Acupuncture and Moxibution Medicine, Dong-eui Oriental University Hospital. Medical records of inpatinets who underwent facial ENoG, NET test were analyzed. Changes of HBGS grade and Yanagihara's score were also evaluated. We classified inpaients acording to Sasang constitution by consulting to Department of Sasang constitutinal medicine, and to Hyungsang classification(Dam-body, Bangkwang-body) by measuring under medical system of 3D facial shapes(RS-400FL). The constitutional differentiation and general characteristics were initially analyzed, and valuse on ENoG, NET were correlated with constitutinal differentiation. Results of HBGS and Yanagihara's score were also correlated with constitutinal differentiation. Results : 1. Each 39.2 percent of idiopathic facial palsy inpatients were the Taeeumin and Soyangin, 21.6 percent were the Soeumin. 2. 75.5 percent of idiopathic facial palsy inpatients were the Bangkwang-body, 24.5 percent were the Dam-body. 3. 34.3 percent of idiopathic facial palsy inpatinets were the Taeeum-Bangkwang, 21.6 percent were the Soyang-Bangkwang, 19.6 percent were the Soeum-Bangkwang, 17.6 percent were the Soyang-Dam, 4.9 percent were the Taeem-Dam, 2 percent were the Soeum-Dam. 4. By sex, the each ratio of Taeeumin, Soeumin, Bangkwang-body, Taeeum-Bangkwang, Soeum-Bangkwang, Soyang-Bangkwang was higher in female, that of Dam-body, Taeeum-Dam, Soyang-Dam was higher in male. 5. By relations between Sasang constitution and Hyungsang classification, the each ratio of Taeeumin and Soeumin was higher in Bangkwang-body. 6. By values on ENoG and NET, evaluations of HBGS's grade and Yanagihara's score, there were no significant difference. Conclusions : In idiopathic facial palsy inpatients, the proportion of Taeeum and Soyang among the Sasang constitution was higher, that of Dam among the Hyungsang classification was higher, that of Taeeum-Bangkwang among the Sasang combined with Hyungsang was the highest. It would seem that Bangkwang-body, female were closely related to Taeeumin, Soeumin. Also, Dam-body were closely related to male. But when comparing groups, there was no statistically significant difference in prognosis and improvement.