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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Engineering Geology
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Journal DOI :
The Korea Society of Engineering Gelolgy
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Volume & Issues
Volume 16, Issue 4 - Dec 2006
Volume 16, Issue 3 - Sep 2006
Volume 16, Issue 2 - Jun 2006
Volume 16, Issue 1 - Mar 2006
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Homogenization Analysis for Calculating Elastic Modulus of Composite Geo-materials
Seo Yong-Seok ; Yim Sung-Bin ; Baek Yong ; Kim Ji-Soo ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 227~233
Bedrock is inhomogeneous for its genetically diverse origins and geological conditions when it forms, and especially, conglomerates and core-stones are one of these typical composite geo-materials composed of weak matrixes and strong pebbles. Mechanical properties of these composite bedrocks, like a conglomerate, generally vary depending on the mechanical properties and distributions of pebbles and the matrix. Therefore, regarding the consequence of understanding mechanical property of bedrocks in the designing slopes, tunnels, and other engineering facilities, empirical rock classification methods generally applied in the mechanical property modeling may not be suitable and rather, we may need some other classification methods, or tests more specific for these inhomogeneous composite bedrocks. This study includes a series of analyses to see elastic behaviors and modulus of composite geo-materials using homogenization theory. Forty nine case models were made for the elastic analysis with considering 5 factors such as gravel content, gravel size, strength of matrix, sorting and dip angle. The results analyzed are applicable to calculate elastic modulus of composite geo-materials as conglomerates and core-stones.
Acoustic Emission Property and Damage Estimation of Rock Due to Cyclic Loading
Jang Hyun-Shic ; Ma Yon-Sil ; Jang Bo-An ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 235~244
Granite cores were sampled within Korea Atomic Energy Research Institute and cyclic loadings up to 1550 cycles were applied. Microcrack development in samples due to cyclic loading was estimated using Acoustic Emission(AE) method. AE showed two different types depending on numbers of cycle. Type 1 appeared at low cycles and had low energy and diverse frequencies, while type 2 appeared at high cycles and had high energy and uniform frequency. AE property of type 1 indicates voids and pre-existing microcracks in samples may close or propagate up to certain length. Microcracks may be sheared or closed during loading and are recovered from shear or opened during unloading when AE of type 2 were measured. P wave velocities and Felicity ratios were measured at 50, 150, 350, 750, 1550 cycles. P wave velocities were almost the same regardless of number of cycles applied. However, Felicity ratios were much lower than 0.9, indicating that microcracks were developed within samples. This result indicates that Felicity ratio is a better tool than P wave velocity to estimate the damage of rock.
Characteristics of Hydrodynamic Dispersion Using a Natural Gradient Tracer Test in a Fractured Rock at the Jwacheon-dong, Busan City
Chung Sang-Yong ; Kang Dong-Hwan ; Kim Byung-Woo ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 245~254
Using a natural gradient tracer test, the characteristics of hydrodynamic dispersion according to each depth of a fractured rock were studied, and the effective porosity and longitudinal dispersivity of the fractured rock were estimated. The difference of vertical hydrodynamic dispersion was identified by concentration breakthrough curves linear regression analyses of bromide concentrations according to depths versus time, and hydraulic fracture characteristics at two intervals of the monitoring well. Higher concentration and faster arrival time at GL- 18 m depth (RQD 13%, average joint spacing 2 cm, TCR 100%) than at GL- 25 m depth (RQD 41%, average joint spacing 7 cm, TCR 100%) resulted from shorter distance and more fractures. Tracer was transported through the 1 st fractures until the arrival of its peak concentration and through the 2nd fractures or matrix diffusion after the arrival of its peak concentration. The increase/decrease slopes of bromide concentration versus time were 3.46/-1.57 at GL-18 m depth and 3.l9/-0.47 at GL- 25 m depth of the monitoring well. So the faster bromide transport was confirmed at GL- 18 m depth with more fractures. The concentration increment of bromide was fitted by a Gaussian function and the concentration decrement of bromide was fitted by an exponential function. Effective porosity and longitudinal dispersivity estimated by CATTI code were 10.50% and 0.85 m, respectively.
Resistivity Tomography in an Inclined Borehole to Surface Purvey Using a Pole-dipole Array
Park Jong-Oh ; Kim Hee-Joon ; Park Chung-Hwa ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 255~263
In an electrical tomographic survey using an inclined borehole with a pole-dipole array, we must consider several factors: a singular point associated with zero potential difference, a spatial discrepancy between electrode and nodal point in a model due to a inclined borehole, and a variation of geometric factors in connection with a irregular topography. Singular points which are represented by the normal distance from current source to the ground surface can be represented by serveral regions due to a irregular topography of ground surface. The method of element division can be applied to the region in which the borehole is curved, inclined or the distance between the electrodes is shorter than that of nodal points, because the coordinate of each electrode cannot be assigned directly to the nodal point if several electrodes are in an element. Test on a three-dimensional (3-D) synthetic model produces good images of conductive target and shoves stable convergence.
A Study on Problems and Improvements of Face Mapping during Tunnel Construction
Kim Kwang-Yeom ; Kim Chang-Yeng ; Yim Sung-Bin ; Yun Hyun-Seok ; Seo Yong-Seok ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 265~273
Face mapping during tunnel construction is useful and critical to predict the characteristics and stability condition of following tunneling sections and to select optimum support pattern. Therefore, a detailed geological survey of the tunnel faces, as important as a routine underground survey and a RMR evaluation, should provide critical information of the tunnel face condition in terms of the engineering geological condition and the safety of working environment for the following tunneling section. But the results of the face investigation have not been applied satisfactorily during tunneling due to limitation of technique, experience and time. This study analyze problems of face mapping in tunnel construction site by using statistical results of face mapping sheets obtained from completed tunnels, and suggest several opinions to improve face mapping during tunnel construction.
A Test for Characterization on Landslides Triggering and Flow Features of Debris using a Flume test Equipment
Chae Byung-Gon ; Song Young-Suk ; Seo Yong-Seok ; Cho Yong-Chan ; Kim Won-Young ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 275~282
This study was conducted laboratory flume tests to identify landslide features and flow characteristics of debris using a flume test equipment. Under the several test conditions dependent on rainfall intensity and slope angle, the authors measured pore water pressure, slope failure and displacement, spreading area of debris on a regular time interval. The test processes were also recorded by video cameras and digital still cameras. According to the test results, pore water pressures have trends of direct proportion to the rainfall intensity and the slope angle, resulting in high potential of landslide triggering. The spreading area of debris is also increased with the slope angle and the rainfall intensity as well as the rainfall duration.
Evaluation of Support Requirements for the Single Shell Tunnels from the Case Study of Rock Mass Classifications
Kim Hak-Joon ; Lee Seong-Ho ; Shin Hyu-Seong ; Bae Gyu-Jin ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 283~291
Shotcrete is used as a permanent lining in single shell tunnels even though shotcrete has been used as a temporary lining in NATM tunnels. Therefore, the accurate evaluation of strength parameters is very crucial because the reliable estimation of loads acting on the shotcretes is necessary to maintain the stability of tunnels. The evaluation of strength parameters of the ground far the single shell tunnels should be investigated to adapt the method in Korea because the geological condition of Korea is different from that of other country. Rock classification and strength parameters obtained from 25 tunnel sites were investigated for this study. Support types fur the different rock classes are suggested for the single shell tunnels in Korea based on the NMT because Q-system has been widely used in Korea. The support types in terms of both Q and RMR values are given based on the correlation of Q and RMR values obtained from the case studies.
Analyses of Correlation Between Groundwater Movement and Tidal Effect in West Costal Landfill Area
Park Jong-Oh ; Song Moo-Yaung ; Park Chung-Hwa ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 293~300
The groundwater movement in the west costal landfill area was analyzed by measuring N value by Standard Penetration Test, coefficient of permeability by falling head method, linear structure analysis by Digital Elevation Method, groundwater flow direction and rate by flowmeter logging due to tidal variation in the each borehole. The coefficients of permeability of the weathered zone and of the marine deposit showed similar values although some values of weathered zone show smaller values than those of the marine deposit. The major groundwater flow and rate in the marine deposit observed as east-west direction due to tidal variation, but on the other hand it was observed as N45E in weathered zone which is the major direction of the linear structures in the area. 2 hours delayed changes of the groundwater flow direction was observed during the 24 hours observation, and it seems to be a travel time of the tidal wave which cause the continuous change of the hydaulic gradient of the groundwater.
Geotechnical Diagnosis System for Preventing a Ground Subsidence Relating with Cultural Heritage
Kim Man-Il ; Yang Dong-Yoon ; Lee Kyu-Shik ; Jeong Gyo-Cheol ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 301~306
Damages of cultural properties is caused by subsidence of foundation relating stone structures. To prevent of these structures, ground monitoring should be achieved certainly. Representative ground subsidence cause is saturated and unsaturated condition that is produced repeatedly by groundwater level fluctuations. It controls role that decrease porosity or effective porosity of soil media. Estimation of physical properties can predict from reaction of dielectric constant. Variations of dielectric constants are measured from physical characteristics change of pore, soil particle, air and water which are consisted to ground. Therefore, ground subsidence monitoring is thought that quantitative measurement is available using dielectric response of media.
Technique for Measuring Displacement ahead of Tunnel Face
Seo Yong-Seok ; Yim Sung-Bin ; Park Si-Hyun ; Ahn Myung-Woon ; Woo Sang-Baik ;
The Journal of Engineering Geology, volume 16, issue 3, 2006, Pages 307~313