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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Civil Engineers
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Korean Society of Civil Engeneers
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Volume & Issues
Volume 15, Issue 6 - Nov 1995
Volume 15, Issue 4 - Jul 1995
Volume 15, Issue 3 - May 1995
Volume 15, Issue 2 - Mar 1995
Volume 15, Issue 1 - Jan 1995
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Three Dimensional Dynamic Response Analysis of Tunnels by Boundary Elements
Lee, Chan-Woo ; Kim, Moon-Kyum ; Hwang, Hak-Joo ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 743~743
In this work 3D dynamic response of uderground tunnels due to trains is numerically obtained using boundary elements under non-relaxed boundary conditions. The problem is formulated in the time domain using the boundary elements. The fundamental solutions used in this work are the Stokes solutions of the three dimensional transient elastodynamics. Linear and constant elements are used in order to compare the efficiency of these elements. The effects of the truncated boundary are examined through the various free surface modellings.
Analysis of Reactor Containment Building under Accident Pressure-Temperature Leading
Park, Yong-Myung ; Bae, Hwan-Chul ; Lee, Lee-Hwan ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 755~755
In this study, the prestressed concrete cylinderical shell and hemispherical dome of YongGwang 3 & 4 reactor containment building has been analyzed by two different methods under LOCA pressure-temperature loading history. The first method uses usual RC member design method which performs individual elastic analysis for mechanical and thermal loadings, and evaluates the stresses of reinforcing bar and concrete by using a existing RC section stress analysis program. The second approach performs material nonlinear analyses for evaluation of stresses under combined mechanical and thermal loadings, and uses a layered model to represent concrete, bar and liner plate. The first method has been performed by exing programs, and the second method by CONSHELL developed in this study The loading combination considered is 'Abnormal Condition
'. The results by two approachs indicate that the stresses of bar show relatively coincident at geometrically continuous area such as mid-height of cylinder, but are somewhat different at basemat-cylinder junction with discontinuity and dome with double curvature.
Analytic Studies on the Fluid-Structure Interaction Effects in Rectangular Liquid Storage Tanks
Koh, Hyun-Moo ; Kim, Jae-Kwan ; Park, Jung-June ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 765~765
Analytic solution procedures are presented for evaluating dynamic responses of rectangular liquid containers under the horizontal and/or vertical seismic excitations incorporating fluid-structure interaction effects due to the wall flexibility. The liquid containers with rectangular plane are assumed to be fixed to the ground. Solutions for both two dimensional and three dimensional models are obtained by applying Rayleigh-Ritz method. Beam vibration modes are employed as assumed mode shape functions for 2-D analysis and approximate plate vibration modes for 3-D model respectively. It is demonstrated that by increasing the number of modes the solution converges rapidly. It is found that responses of 3-D model show quite different aspects compared to those of 2-D model. Therefore use of a 3-D model may have to be considered for the dynamic analysis of flexible rectangular liquid containers.
Mechanical Behavior of Separately-Placed Reinforced Concrete Bridge Slabs under Low Cyclic Loading
Oh, Byung-Hwan ; Lee, Hyung-Joon ; Lee, Myung-Gue ; Baik, Shin-Won ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 777~777
The flexural and horizontal shear behavior of two-layered concrete slabs under cyclic loadings is investigated in the present study. An experimental program was set up and several series of separately-placed concrete slabs have been tested to study the effect of different interface surface conditions between old slab and overlay under cyclic loading. The cracking and ultimate load behavior under cyclic loadings for various cases including acryl emulsion treatment and doweled joints have been studied. The present study indicates that the horizontal interfaced slabs with less amount of dowel bars show layer separation under cyclic loadings. However, the two-layered slabs with proper dowel bars showed good performance under cyclic loadings. The present study provides basic data for realistic design of separately-placed RC slabs. Further studies are necessary to propose a reasonable fatigue-design guide for two-layered reinforced concrete slabs.
Assessment of Response Reduction Factor Based on Linear Statistical Model
Hong, Won-Kee ; Jang, Il-Young ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 787~787
The statistics of uncertainty in structural engineering materials can be obtained by experiments. In this study structural engineering materials were tested to help quantify the uncertainty. Additional random variables are introduced to incorporate both the confidence in the analytical accuracy of engineering mechanics associated with structural response quantities and the uncertainty in the construction quality control. This paper, recognizing engineering problems with high level of uncertainties both due to the engineering materials and engineering equations derived from principles of structural mechanics, proposes reliability based evaluation methodology of the reinforced concrete masonry shear walls. Linear statistical technique has been considered to treat the uncertaines that practicing engineers often face.
Double Integration Method for Dynamic Analysis of Structures under Earthquake Load
Kim, Jin-Ho ; Kim, Dong-Ok ; Lee, In-Won ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 797~797
The computational time in direct integration method depends on the integration time interval directly. The integration time interval is often restricted by the rapidity of variation in excitation, or by yielding and unloading in the structural members. Especially in case of structural analysis under earthquake load or non-linear problems, quite a small time interval must be used to assure high precision. In the proposed method, original equation of motion is transformed into equivalent equation of motion through double integration and an efficient numerical integration method for solution is employed. The proposed method permits larger time intervals to be used than usual techniques, and eliminates the difficulties for solution at yielding and unloading in structural dynamic analysis. The proposed method expects the reduction of computational time with high accuracy.
Free Vibration Characteristics of Rectangular Plates with Initial Curvature
Shin, Dong-Ku ; Lee, Ho-Hyung ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 809~809
The effects of initial curvature on the free vibration characteristics of rectangular isotropic plates are investigated. The equations of motion are derived as a function of displacements by using von Karman's finite strains. The nonlinear equations of motion is subsequently linearized by neglecting the higher order terms and the typical linear eigenvalue problem is obtained. The free vibration analysis based on the Mindlin type shear deformation plate theory is performed by the finite element method. The double sinusoidal form of initial imperfection is introduced and both simply supported and fixed boundary conditions are considered. Numerical examples are presented to observe the free vibration characteristics of rectangular plates with various aspect ratios, boundary conditions and imperfection shapes.
Inelastic Analysis Considering Effects of Gravity Loads for Steel Framed Structures
Park, Chang-Ho ; Lee, Dong-Guen ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 821~821
Most of large structures are designed with strong column-weak beam steel frame type of having good seismic performance Inelastic deformations of the structures are concentrated in beams governed by flexural moment. Therefore to accurately evaluate inelastic behaviors of the structure, first inelastic behavioral characteristics of the beams should be estimated. Most of beams are subjected to constant gravity load and cyclic moment due to seismic excitations. Moment gradient influencing inelastic behavior is determined by bending moment due to gravity load and the directions of seismic load. Therefore objective of this paper is to estimate the effects of gravity load on inelastic behavior of beams and to develop plastic hinge model considering the effects of gravity load. First, using layer model inelastic behaviors of beams are esimated. The effects of types and magnitude of gravity load, section shape and beam length on the inelastic behaviors of beams are investigated, the results using layer model are verified by quasi-static tests, and the effects of gravity loads are experimentally evaluated Plastic hinge properties of plastic hinge model which can consider the effects of gravity load are modelled by based on analytical and experimental results. Using proposed plastic hinge model, seismic analyses for steel framed structures are performed and, then, the effets of gravity load on inelastic behavior of steel frames are estimated by evaluating ductility demand and damage index.
Efficient Analysis of Framed Structures for Vertical Vibration
Chung, Gil-Young ; Song, Jong-Keol ; Lee, Dong-Guen ; Kim, Woo-Bum ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 835~835
The effect of the first mode vibration is predominant in seismic response of a framed structure while vertical vibration of a beam is significantly influenced by higher modes of vibration. Therefore, a beam can be modeled using only one element for seismic analysis of framed structures while several elements must be used to represent a vibrating hem As a result, analysis of a framed structure for vertical vibration requires increase number of elements leading to more complicated model with many degrees of freedom which requires large amount of computing resources for dynamic analysis. An efficient analysis method for vertical vibration of framed structures are proposed in this paper which is presented in three steps. The first step is to determine minimum nodes required to obtain dynamic response for vertical vibration. The second step is reduction of degrees of freedom through matrix condensation for efficient dynamic analysis of the structure. In this stage, the most effective selection of master degrees of freedom is pursued. The third step of this study employs the substructuring technique for local vertical vibration analysis. Efficiency and accuracy of the method proposed in this paper is verified comparing the analysis results to those of experiments performed using a three story framed structure.
Improved Controlled-Strain Diametral Fatigue Testing Procedure in Asphalt Concrete : Development and Application
Kim, Nak-Seok ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 845~845
This paper presents the development of a new controlled-strain diametral fatigue testing procedure and the comparison of test results from the controlled-stress and controlled-strain diametral fatigue tests. It has to be noted that the controlled-strain and controlled-stress tests in this paper actually means the control of deformation and vertical load on the specimens. respectively The resilient modulus testing future developed by MTS Systems Corp. in accordance with ASTM D 4123 was used with the MTS closed-loop servohydraulic system. The development of controlled-strain diametral fatigue testing procedure was accomplished by controlling the recoverable horizontal deformation. The recoverable horizontal deformation wave forms were created by the computer program and sent to the Microprofiler in the U which is a programmable function generator acting as a circular buffer. The fatigue test results showed that the dissipated energy increased with increasing number of load repetitions in the controlled-stress diametral fatigue tests, whereas, for the controlled-strain diametral fatigue tests, the dissipated energy decreased with increasing number of load repetitions. Also, the increase in total cumulative dissipated energy with increasing number of load cycles to failure was more noticeable in controlled-stress diametral fatigue test than that in controlled-strain diametral fatigue test.
Distribution of Surface Water Using Optiaml Operation Model
Yoon, Yong-Nam ; Kim, Chung-Hoon ; Kim, Tae-Kwen ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 855~855
The objective of this study is to develop an optimal model for the distribution of surface water resources in an agricultural river basin which has a nulti-purpose dam. The optimization model consists of two models : normal period model and abnormal period model. The normal period model minimizes the difference between the cost and benefit under the condition of satisfying all the agricultural water demands. When the water level in the dam becomes lower than a certain level for current period, or when the normal period model is infeasible, abnormal period model is call upon, and it gives the first priority to satisfying the agricultural water demands rather than to maximizing the hydropower generation benefits. The normal period model is a nonlinear programming problem due to the nonlinearity inherent in the objective function which takes the hydropower generation into account. Since the model has too many variables to be solved directly by an existing NLP solver, a successive linear programming technique using the Frank-Wolfe algorithm is utilized for the approximate solution. The abnormal period model is an LP problem. Since the model recursively computes the water resources supplies to demand from any operation period to the end of the water year. it requires a sequences of reservoir inflows and agricultural demands to be synthetically generated. A stochastic model is employed to generate the sequences of the variables. Dongiin Agricultural Unit. which includes Sumjin multi-purpose dam and Donjin river basin. is selected for the application of the model. The results showed that hydropower generated was significantly increased. and that all the agricultural demands were satisfied for the duration of analysis. which was not the case for the past real system operation.
An Analysis of Standing Wave Pressure Acting on Mixed Type Breakwater
Oh, Young-Min ; Lee, Kil-Seong ; Chun, In-Sik ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 865~865
The standing wave pressure is very important to the design of vertical breakwater. Thus, a numerical model to calculate the standing wave pressure accurately is essential in the design of coastal structures like breakwater in addition to hydraulic model tests and simple wave pressure formula. The wave pressure acting on the mixed type breakwater was calculated with the numerical model which generates the double-peaked standing wave pressure which occurs in highly nonlinear waves near to breaking limit. The model was calibrated by hydraulic experiment and Goda's formula and the stability of breakwater was ·also analyzed. From the application to the mixed type breakwater. it is found that the sliding is more critical to the stability of breakwater than the overturning. and a conservative design condition is provided by the numerical model in the case of small waves but by the Goda's formula in the case of high waves.
A Study on the Variation of Bed Elevation in Main Channel of the Han River
Lee, Jae-Soo ; Yoon, Yong-Nam ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 875~875
The accurate prediction of the variation of bed elevation is very difficult because of the complex mechanics of sediment movement during runoff Models to simulate the variation of bed elevation have been developed and CHARIMA model which was developed at the lowa Institute of Hydraulic Research is one of them. The purpose of this study is to apply the CHARIMA model to the Han River (from Indo bridge to Kwangjang bridge) and to compare the simulated results with the observed bed elevation. In this study tong and short term variations of bed were simulated. From the results of this study the CHARIMA model can be applicable to the Han River. and TLTM and Engelund-Hansen methods show better results than Power Law and Ackers-White methods in the estimation of bed elevation. Also the results show severe degradation of bed at rho Dongiak bridge and between the Hannam bridge and the Gumho bridge.
A Cross-shore Profile Model in Wave-current Coexisting Fields
Park, Il-Heum ; Lee, Jong-Sup ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 885~885
For the prediction of beach evolutions in wave-current coexisting fields, the model of process-based approach proposed by van Rijn is applied. The total sediment transport rate is defined as the sum of current-related and wave-related ones, and each transport rate by waves or current is divided into the suspended load and the bed load. To reduce the run time in the calculation of external forces of the sediment transport, the nonlinear hyperbolic wave theory that need not an iterative scheme and the analytical solutions of return flow in and outside the surf zone are applied. And the transition zone related to the turbulence development in the surf zone is considered. The model results are verified with the laboratory data, and compared with those of 5 other morphological models. The present model predicts the bar formation near the breaking point well.
An Efficient Application of Moisture Content and Hydraulic Conductivity Hysteresis in Analyzing Unsaturated Flow
Park, Chang-Kun ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 899~899
The water retention function and the unsaturated hydraulic conductivity which indicate the hydraulic characteristics of the interesting soil are required in analyzing the unsaturated flow. An efficient method to consider the not-negligible moisture content and conductivity hysteresis is proposed, and its validity is investigated through the comparison of the experimental data. The proposed method is such that van Genuchten(1980)'s water retention function and the conductivity model obtained from Mualem(1976)'spore-structure model are used, and the values of the parameters of the above two models are used as the same values which are estimated from the experimental data of the water retention function hysteresis. The simulated values by this method are relatively well agreed with the experimental data of the Dune Sand and the Caribou Silt Loam.
A Study on Stable Alluvial Channels Based on Bed Evolution in Main Channel of the Han River
Paik, Joong-Cheol ; Cho, Won-Cheol ; Heo, Jun-Haeng ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 907~907
Main channel of the Han river has been changed artificially due to the continuous improvement of low water channel and dredging. Analysis of the long term effects of artificial bed change has been done in 23-km reach of the Han river, using CHARIMA, the one dimensional numerical simulation model for unsteady water and sediment movement. And determination of hydraulic geometry based on rational method has been conducted to present base of stable channel management. The results show that the test river reach is generally stable and artificial changes may be the main factors of bed evolution. After stable channel geometry is determined based on rational method by considering sediment discharge and median size. the modifications of low water channel width and slope are required for stable alluvial channel.
Basin Level Unit Commitment for Hydropower System Using Mixed Integer Programming
Yi, Jaee-Ung ; Cho, Won-Cheol ; Heo, Jun-Haeng ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 917~917
Unit commitment scheduling model using Mixed Integer Programming (MIP) that improves the operational efficiency for hydropower systems is developed in this study This model consists of three different models. The first model develops an hourly water release schedule for water driven plants. Based on this water release schedule, the second and the third models decide the unit commitment schedules for all hydropower plants in the basin. A case study, using data from Lower Colorado River hydropower plants, is provided to illustrate applicability of model. The results showed that this model provided generation control tool that regulates the power system while improving the average basin efficiency over 3 percent. The memory and computation requirements are small to apply to practical sized system and any changes in schedules or demands can be adapted in real time.
A Development of Integrated NAS Model System for Estimating and Scheduling
Park, Hong-Tae ; Lee, Bae-Ho ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 929~929
An essential function for the effective performance of project constructions may broadly be divided into project scheduling and control of schedule and cost. Of late, in project construction fields, various computer softwares of project scheduling and control of schedule and cost are being used for introduction of scientific network method. It was, however, found impossible to apply in practice the optimal schedule. because functions of scheduling and estimating are separated and analyzed. and as a result. progress analysis could not be timely performed and thus the effectiveness of field applications was not satisfactory to the input investment. The present study aims to present a conceptual model to be incorporated in developing a computer of project scheduling and control with all necessary informations covering project schedules and project costs by each work item. The model comprises the modules of estimating of scheduling and control of schedule and cost. By doing this. it is expected to attain standardization and simplification of the system performance with all necessary informations put into computer This will further produce an effective construction management together with estimating and scheduling, and the results will be fed back various information to estimating and scheduling for control purposes. For the ease of construction and management of the network a standard procedure was introduced with by stored framed standard subnetwork information based on standard work breakdown structure-WBS to make it possible to reframe the network only through modification of work items in the computer systems in connection with design modifications etc. The study also presents the details of the model systems by each function and maps out the modules of estimating, scheduling and control systems in a form directly applicable to system development in an automated evirorment. The methodology adopted in the present study will be able to use not only for the civil works but also buildings in common.
A Study on the Characteristic of Bessel Geoidal Height Using the Deflection of Vertical and GPS/leveling
Kang, Joon-Mook ; Park, Woon-Yong ; Kim, Hong-Jin ; Choi, Jong-Hyun ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 945~945
In determination of 3-dimensional coordinates using the GPS, coordinate transformation and determination of orthometric height are based on geoidal height. Thus the accuracy improvement of geoidal height model on Bessel ellipsoid or WGS 84 ellipsoid has an effect on the accuracy improvement of coordinate transformation and determination of orthometric height. In this paper, difference between Bessel ellipsoidal height and WGS 84 ellipsoidal height is derived from least square method of surface fitting for deflection of vertical that is based on Bessel and WGS 84 ellipsoid. Also, Bessel geoidal height model is resulted from combining GPS/leveling method with difference between Bessel ellipsoidal height and WGS 84 ellipsoidal height. This paper suggests efficiency of coordinate transformation between WGS 84 datum and Bessel datum from Bessel geoidal height model.
A Characteristic Analysis of Edge Detectors to Extract the Information of Topography and Buildings from Aerial Images
Yoo, Hwan-Hee ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 953~953
Detecting or extracting edge of the topography and the man-made objects in aerial images is important in Geo-Spatial Information System or Real-Time Mapping System that needs a data of digital format. In this report Sobel detector. Prewitt detector, Compass detector, Roberts detector among various edge detectors were selected and results of applying these edge detectors to test image with various edge styles and SNR values were presented and analyzed. In the case of vertical and diagonal edge displaced from the center of the mask, the variation in sensitivity for the Sobel detector is much less than those for other detectors. Also, another important property that edge detectors should have is low sensitivity to random noise. The results for noise sensitivity analysis show that Sobel detector and Prewitt detector which are the so-called "differential operators" are far better than Compass detector which is "templates matching operator" at defecting edges in the presence of noise.
A Study on the Application of Rapid Measurements with Global Positioning System for Precise Geodetic Surveying
Park, Woon-Yong ; Nim, Young-Bin ; Lee, Jae-One ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 961~961
The Global Positioning System was primarily designed for military navigation system by the US Department of Defense (DoD) in 1973. It has been successfully used in civilian geodetic surveying since 1983. Thereafter, it has been proved that GPS is the most valuable and excellent method, that ever exist in positioning system. Previous application of GPS was mainly based on the time-consuming static measurement which is combined with the results of existing triangulation or trilaterlation. Presently, however, new rapid methods are developed by using the experience of static method. These satisfy the most advantage of GPS in aspect of rapidity, accuracy and economy In the relative kinematic methods, one antenna is always fixed at reference station and the other one travels sequentially to measuring points. Although rapid measurement method takes a few seconds or minutes, it cope with the accuracy of static method. In this paper, the characteristics of new methods are presented Also many experiences are discussed about the coastal GPS experiment where the Kinematic Differential GPS is needed to detect the morphologic changes.
Microscopic Analysis of the Effects of Water Contents and Pore -Size on Shape Factor
Lee, Kwang-Yeol ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 975~975
circular shape of pores. But the actual shapes of pores are not in circular and are of random shapes. In this study, however, ten random shapes of pores were generated using Auto-Cad. and a method for determining the hydraulic radius for the random pores at various modes in size was developed. Analysis of the effects of pore shapes on the
relationship were conducted and illustrated graphically. Also, three pore modes (single. hi-modal, multi-modal) were utilized for the microscopic analysis of the effects of pore-modes on the
relationship. The results of this study can be utilized to evaluate the behavior of contaminants in soils for a remediation of contaminated soils.
A Study on the Estimation of Blast Vibration Velocity Using R.Q.D
Chun, Byung-Sik ; Oh, Min-Yeoul ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 983~983
The main purpose of this study is the estimation of blast vibration for controlling blast vibration during subway tunnel excavation. The theoretical value derived from the previous study and measured value during tunnel excavation was compared. According to the result of comparison between the previously reported value of vibration velocity and the experimental value measured in subway tunnel blasting. the blast vibration velocity showed similar range and the deviation was large in case of Granite in Seoul area. In case of Gneiss, both the range of blast vibration velocity and the deviation showed relatively large. The relations between blast vibration and Rock qualify Designation (R.Q.D) can be represented as V=0.0014 R.Q.D+0.170, correlation (r)=0.65 for Granite, and that of a Gneiss was represented as V=0.049 R.Q.D+0.112, correlation (r)=0.90 respectively.
A Study on the Stability of Anchored Retention Walls for Underground Excavation
Hong, Won-Pyo ; Yun, Jung-Mann ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 991~991
When deep excavations are performed in urban areas, sufficient investigation should be prepared for the stability of excavated ground and the influence on adjacent structures. Especially, the excessive deformation of retention walls, which causes ground settlement at behind ground of the walls, may induce a considerable danger on the stability of adjacent structures and excavation construction. Recently, for prevention of construction disaster and safe construction of retention walls, construction management based on the field measuring has been increased. However, since available judgement criteria are not prepared, it is difficult to make correct judgement on the field measuring results. The purpose of this paper is to establish a quantitative criterion which can be applied on judgement of the stability in deep excavation according to the condition of construction of anchored retention walls. It was possible to evaluate the quality of construction management by investigating the relations between lateral earth pressure acting on the retention walls and horizontal displacement of the walls. And also quantitative safe criterion to judge stability of retention walls was established from the relations between horizontal displacement measured by inclinometer installed behind retention walls and excavation depth as well.
A Study on the In-Situ Adaptability of Shallow and Deep Mixing treatment Method by Solidifying Agent
Doh, Duk-Hyun ; Kong, Kil-Yong ; Oh, Chang-Mok ; Yu, Chan ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 1003~1003
Five marine soft clays from south-western coastal area were tested for improvement with three solidifying agents and varying water contents. Unconfined strength test was performed at the laboratory after standard curing and the result was applied to the field as a pilot study. Generally about 9% weight ratio of solidifying agent to the dry soil was considered as an optimum economically although it varies slightly with clays. According to the test result with solidifying agent ESC, mixing and spreading solidifying agent to the sand mat to improve the strength for the traffic of heavy equipment is believed to be an feasible alternative. The Jinhae-bay clay treated with ESCA showed more strength for both the brown and green colors than other solidifying agents. but soaking after 14 days of standard curing showed low strength improving rate compared to the continuous standard curing.
A suggested Method to Predict Uniaxial Compressive Strength of Korean Granites by Point Load Strength
Lee, Su-Gon ; Lee, Song ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 1015~1015
Point load test has proved an easy and proper method to quantify the stage of weathering of Korean granites. It also produces a fairly reliable strength index tp estimate uniaxial compressive strength. Meanwhile, the size correction formulae commonly adopted in the process of the test were proven rather unsuitable to predict the size-corrooted point load strength of Korean granites. Point load strength values have a well-defined direct linear relationship with uniaxial compressive strength values of Korean granites, The inclination of the straight line for Korean granites is 15.8 and 18.2. by using the minimun cross-sectional area and actual fracture area methods respectively. Both inclinations are lower than the widely adopted value of 24. Point load strength values are influenced by the grain size of granite. thus their reliability for predicting uniaxial compressive strength values can be improved by considering seperately the Cretaceous and Jurassic granites. It is recommended however that before using the published formulae. their reliability with respect to rock type should be studied.
Stress-Strain Relation of Remolded Clay Using Intermediate Principal Stress Control Test
Park, Byong-Kee ; Jeong, Jin-Seob ; Kang, Kwon-Soo ; Lee, Kang-Il ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 1029~1029
Point load test has proved an easy and proper method to quantify the stage of weathering of Korean granites. It also produces a fairly reliable strength index tp estimate uniaxial compressive strength. Meanwhile, the size correction formulae commonly adopted in the process of the test were proven rather unsuitable to predict the size-corrooted point load strength of Korean granites. Point load strength values have a well-defined direct linear relationship with uniaxial compressive strength values of Korean granites, The inclination of the straight line for Korean granites is 15.8 and 18.2. by using the minimun cross-sectional area and actual fracture area methods respectively. Both inclinations are lower than the widely adopted value of 24. Point load strength values are influenced by the grain size of granite. thus their reliability for predicting uniaxial compressive strength values can be improved by considering seperately the Cretaceous and Jurassic granites It is recommended however that before using the published formulae. their reliability with respect to rock type should be studied.
Effect of Base Roughness of Strip Footing on Settlement and Ultimate Capacity in Sandy Foundation
Yoo, Nam-Jae ; Lee, Sang-Duk ; Park, Byung-Soo ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 1041~1041
This research is an experimental and numerical study of investigating effects of base roughness of strip footing in sandy foundation on load-settlement characteristics, ultimate bearing capacity, and failure mechanism. For model foundation. Jumunjin Standard Sand was used and prepared in the specially built model container to simulate loading conditions of the strip footing in field. Parametric experiments under plane strain conditions were performed by changing properties of interface between foundation and footing such as placing vinyl. aluminum. sand paper, and sand itself beneath the model footing. Relative densities of sandy foundation was also changed during tests. Ultimate values obtained from tests were compared with estimated values by using limit equilibrium methods. The load-settlement behavior of footing obtained from tests was also compared with results from using a numerical technique of Finite Element Method with hyperbolic constitutive relation.
Comparison of Soil Characteristics between the Downstream Area of Nakdong River and Sea-Bed of Osaka Bay
Park, Sung-Zae ; Jeong, Gyeong-Hwan ; Seiji, Suwa ; Mitsuhara, Fukuta ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 1055~1055
It is desirable to express the ground information through preparing a GIS (Ground Information System) for the easy utilization of soil characteristics depending on the site. While in the preceeding of performing a research to make a GIS, characteristics of Nakdong River clay and Osaka Bay clay were compared through performing consistency tests, X-Ray diffraction analyses, and powder state non-oriented samplc analyses on samples from both countries. Some differences in soil characteristics between them were found. Based on consistency test results, characteristics of Nakdong River clay were very similar to those of Japanese middle soil. However, results from X-Ray diffraction analyses and analyses of powder state non-oriented samples exhibited that Nak-Dong River clay contains more quartz and feldspar compared to Osaka Bay clay.
Comparative Evaluations of Three-Dimensional Turbulence Models of Surface Thermal Jet
Jung, Tae-Sung ; Lee, Kil-Seong ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 1065~1065
Three-dimensional tubulence models of surface buoyant jet with variable density were established. The models include two 2-equation models (
model and k-1 model) and one 1-equation model (TKE model). The models were applied for thermal jets discharging into a stagnant waters and the simulation results were compared with an hydraulic experimental data set. TKE model gave unstable results and k-1 model has shown the results which velocity is overestimated and temperature is underestimated. In the case of k-1 model. the simulation results were dependent on the model constant
and Prandtl number strongly.
Modelling Vortex Movement Using SOLA Method
Jeong, Shin-Taek ; Kim, Hyo-Seob ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 1077~1077
The SOLA method was applied for the numerical calculation of the time-dependent flows of incompressible fluid. This method is a numerical one, using a high-speed computer for the solution of a finite-difference approximation to the partial differential equations of motion The applications described here are to the development of a vortex-street behind a plate which has impulsively accelerated to a constant speed in a channel of finite depth. and to the movement of vortices over seabed ripples. In the latter case calculated flows agree well with measured flows. The application results demonstrate the model's capability to simulate the related topics in fluid dynamics.
Analysis of Advanced RBC Process for Organics, Ammonia Oxidation and Nitrogen Removal in Sewage
Kim, Eoung-Ho ; Oh, Jung-Woo ;
Journal of The Korean Society of Civil Engineers, volume 15, issue 4, 1995, Pages 1083~1083
This paper presents experimental results in the advanced Rotating Biological Contactor (RBC) process which is designed to oxidate organic compounds and ammonia and to remove nitrogen in sewage. The experimental ranges of the hydraulic loading rate, the organic loading rate and the ammonia nitrogen loading rate are
respectively. Substrate removal rate is explored with hydraulicloading rate and substrate loading rate. respectively Kornegay model is applied to estimate the kinetic parameter of the area capacity constants, p, the Monod half-velocity coefficient, Ks, the yield coefficient, Y and the decay coefficient,
. The test results shows the advanced RBC process promises for future medium or small wastewater treatment process.