• Title/Summary/Keyword: unconsolidated sediments

Search Result 42, Processing Time 0.026 seconds

Clay Mineral Assemblage and Their Origin of Unconsolidated Sediments of Youngjong Island, Western Part of Korea (영종도 비고화 퇴적물의 점토광물 조성 및 기원에 관한 연구)

  • Moon, Ji-Won;Moon, Hi-Soo;Song, Yungoo;Lee, Gyoo Ho
    • Economic and Environmental Geology
    • /
    • v.30 no.6
    • /
    • pp.531-541
    • /
    • 1997
  • Unconsolidated sediments of Youngjong Island were investigated to consider the vertical distribution of clay minerals and their origin. At least three sedimentation units can be recognized by color, magnetic susceptibility, and pH. X-ray diffraction analysis of clay size fraction reveals that illite is the most abundant phase (52.06%), and chlorite (27.16%), kaolinite (16.92%), smectite (3.86%) occur next to it. Detailed XRD study suggests that illitic materials contain fairly large amount of ordinary muscovite derived from the mica schist in Youngjong Island and adjacent area. The relative amount of kaolinite and chlorite is less than those of samples from estuary mouth of several rivers that flow to Yellow Sea and South Sea. Especially smectite content of the present sample is much higher than those of estuary sediments. These indicate that the unconsolidated sediments of tidal-flat deposit in Youngjong Island are largely affected by marine influence and partly affected by sediment in influx from China. However, some degree of source of this unconsolidated sediments is inland origin from adjacent estuary sediment and in situ or nearby weathered materials.

  • PDF

Shear Wave Velocity in Unconsolidated Marine Sediments of the Western Continental Margin, the East Sea

  • Kim, Gil-Young;Kim, Dae-Choul
    • The Journal of the Acoustical Society of Korea
    • /
    • v.22 no.4E
    • /
    • pp.167-175
    • /
    • 2003
  • Shear wave velocity was measured and grain size analysis was conducted on two core samples obtained in unconsolidated marine sediments of the western continental margin, the East Sea. A pulse transmission technique based on the Hamilton frame was used to measure shear wave velocity. Duomorph ceramic bender transducer-receiver elements were used to generate and detect shear waves in sediment samples. Time delay was calculated by changing the sample length from the transducer-receiver element. Time delay is 43.18 μs and shear wave velocity (22.49 m/s) is calculated from the slope of regression line. Shear wave velocities of station 1 and 2 range from 8.9 to 19.0 m/s and from 8.8 to 22 mis, respectively. Shear wave velocities with depth in both cores are qualitatively in agreement with the compared model〔1〕, although the absolute value is different. The sediment type of two core samples is mud (mean grain size, 8-9Φ). Shear wave velocity generally increases with sediment depth, which is suggesting normally consolidated sediments. The complicated variation of velocity anisotropy with depth at station 2 is probably responsible for sediment disturbance by possible gas effect.

Usability Evaluation of Tertiary Unconsolidated Sediments for Reclamation (미고결 퇴적층의 재료원 평가)

  • Kim, Sung-Wook;Choi, Eun-Kyoung;Lee, Kyu-Hwan
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2010.03a
    • /
    • pp.699-704
    • /
    • 2010
  • Tertiary unconsolidated mudstones spread throughout the eastern coast of Pohang area. Recently, the demand for high quality filling materials is increasing due to harbors and large-scale residential land development. But the features of the reclaimed land using soft mudstones have not been made clear yet. Unconsolidated rocks are diversely considered according to a different method of the applied geotechnical investigation. This study is examined that the applicability of mudstone as a harbor reclamation material through the laboratory test and pilot test. Expecially, it must be considered that the environmental characteristics of mudstone as a reclaimed materials.

  • PDF

부산 녹산-가덕도 지역에 분포하는 점토퇴적물의 광물조성과 공학적 특성에 대한 비교연구

  • 이선갑;황진연;정성교;김성욱;김국락
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
    • /
    • 2003.09a
    • /
    • pp.107-111
    • /
    • 2003
  • Estuary of Nakdong river area is composed of unconsolidated sediments including clays that are deposited varying from 40 to 70m thick. The purpose of research is the knowledge of the correlation between engineering properties and mineralogy of clay sediments. The correlation analysis carry out multiple regression that have independent variables (Engineering properties) and dependent variables (mineralogy, geochemistry). Engineering properties of clay are correlated with the mineral compositions and geochemical characteristics. The result of the analysis is Wn=-0.6 Feldspar + 1.1 pH + 0.01 TDS + 27.5, Ip=0.36 Clay + 1.44 Vermiculite + 0.94 clay mineral-22.88, P$_{L}$=0.005 TDS - 0.31 Feldspar + 22.43, e$_{o}$=0.02 Vermiculite - 0.01 Quartz + TDS + 0.93, E$_{50}$=1.94 Vermiculite-0.96 Kaolinite -0.53 silt + 49.64, SR=-0.25 Kaolinite + 1.5 pH - 2.3 Conductivity, CC = 0.03 pH + TDS - 0.2, LL = 0.5 Clay + 1.3 Vermiculite + 5.5 Conductivity + 0.8 Caly mineral-20.4.4.4.4

  • PDF

A Refraction Seismic Survey of Unconsolidated Sediments Adjacent Lake Soyang (굴절파 탐사를 이용한 소양호 주변의 미고결 퇴적물 연구)

  • Hong, Myung-Ho;Kim, Ki-Young
    • Journal of the Korean Geophysical Society
    • /
    • v.9 no.4
    • /
    • pp.343-349
    • /
    • 2006
  • In order to study unconsolidated sediments upstream of the Soyang Dam, seismic refraction data were recorded along five profiles of 94 m length. Receiver interval and record length were 2 m and 204 ms, respectively. Recorded data were analyzed using the traveltime tomography and delay-time methods in order to reveal sediment distribution in the investigation site. The acoustic basements are buried at approximately 14 m deep and their thickness shallows to southeast approaching to a hill. On the basement, pre-existing sediments deposited before construction of the Soyang dam lies. This sedimentary layer is composed of paleo-soil and sandy sediments. Above this layer, recent sediments comprise the top layer which is believed to have been deposited since the formation of the dam. Average thickness of this uppermost layer is approximately 1.6 m, which is much thicker than in the downstream.

  • PDF

The Characteristics of Hydrogeological Parameters of Unconsolidated Sediments in the Nakdong River Delta of Busan City, Korea

  • Khakimov, Elyorbek;Chung, Sang Yong;Senapathi, Venkatramanan;Elzain, Hussam Eldin;Son, JooHyeong
    • Journal of Soil and Groundwater Environment
    • /
    • v.22 no.3
    • /
    • pp.27-41
    • /
    • 2017
  • This study dealt with the characteristics and the interrelations of hydrogeological parameters such as hydraulic conductivity, dispersivity and effective porosity of unconsolidated sediments for providing the basic data necessary for the planning of the management and preservation of groundwater quality in the Nakdong River Delta of Busan City, Korea. Groundwater quality in this area has been deteriorated due to seawater intrusion, agricultural fertilizer and pesticide, industrial wastewater, and contaminated river water. The physical properties (grain size distribution, sediment type, sorting) and aquifer parameters (hydraulic conductivity, effective porosity, longitudinal dispersivity) were determined from grain size analysis, laboratory permeability test and column tracer test. Among 36 samples, there were 18 Sand (S), 7 Gravelly Sand (gS), 5 Silty Sand (zS), 5 Muddy Sand (mS), and 1 Sandy Silt (sZ). Hydraulic conductivity was determined through a falling head test, and ranged from $9.2{\times}10^{-5}$ to $2.9{\times}10^{-2}cm/sec$ (0.08 to 25.6 m/day). From breakthrough curves, dispersivity was calculated to be 0.35~3.92 cm. Also, effective porosity and average linear velocity were obtained through the column tracer test, and their values were 0.04~0.46 and 1.06E-04~6.49E-02 cm/sec, respectively. Statistical methods were used to understand the interrelations among aquifer parameters of hydraulic conductivity, effective porosity and dispersivity. The relation between dispersivity and hydraulic conductivity or effective porosity considered the sample length, because dispersivity was affected by experimental scale. The relations between dispersivity and hydraulic conductivity or effective porosity were all in inverse proportion for all long and short samples. The reason was because dispersivity was in inverse proportion to the groundwater velocity in case of steady hydrodynamic dispersion coefficient, and groundwater velocity was in proportion to the hydraulic conductivity or effective porosity. This study also elucidated that longitudinal dispersivity was dependent on the scale of column tracer test, and all hydrogeological parameters were low to high values due to the sand quantity of sediments. It is expected that the hydrogeological parameter data of sediments will be very useful for the planning of groundwater management and preservation in the Nakdong River Delta of Busan City, Korea.

Velocity Anisotropy of Unconsolidated Sediment in the Ulleung Basin, East Sea (동해 울릉분지 미고결퇴적물의 속도비등방성)

  • 김길영;김대철
    • The Journal of the Acoustical Society of Korea
    • /
    • v.20 no.4
    • /
    • pp.87-93
    • /
    • 2001
  • Velocity anisotropy of unconsolidated sediments in the Ulleung Basin, East Sea were studied by using 22 piston cores. Velocity anisotropy shows about 0.4 and 1.2% in the Plain and Slope sediments, respectively. Horizontal velocity is greater than vertical velocity. It is resulted in positive anisotropy. Thus, bedding must be regarded as the principal cause of acoustic anisotropy in the Ulleung Basin sediments. The differences of the value are different from 5 m/s to 18 m/s in the Plain and Slope area, respectively. The relationships between physical properties and velocity anisotropy are clearly grouped. This result suggests that the slope sediments are probably affected by sedimentological (esp. physical properties) changes resulting from diagenesis.

  • PDF

A Study on Geotechnical Properties of Deep-sea Sediments in Clarion-Clipperton Fracture Zone of NE Pacific (북동태평양 클라리온-클리퍼톤 지역 심해저 표층 퇴적물의 지질공학적 특성 연구)

  • Chi, Sang-Bum;Oh, Jae-Kyung;Lee, Hyun-Bok;Kim, Ki-Hyun
    • Ocean and Polar Research
    • /
    • v.25 no.2
    • /
    • pp.133-145
    • /
    • 2003
  • Deep-sea surface sediments were collected using a multiple corer at 20 stations of Clarion-Clipperton fracture zone in the northeast equatorial Pacific to understand latitudinal and longitudinal variations of geotechnical properties. There was a distinct latitudinal variation of geotechnical properties in the study area. The northern sediments showed finer grain size, lower water content and porosity, higher bulk density and specific grain density, lower liquid limits and plastic limits than their southern counterparts. The northern sediments are classified into inorganic clays of low plasticity (fat clays) on plasticity charts and normal to active clay on activity chart, whereas, the southern sediments are classified into fine-grained, highly-plastic, inorganic and biogenic silt or organic clays on plasticity chart and normal to very active clay on activity chart. When shear strength are considered, the northern sediments were found to be in unconsolidated states, while the southern ones to be normal to over-consolidated states. These latitudinal variations in sediment characteristics are likely caused by differences in productivity of surface water that controls sediment compositions, sedimentation rates, and grain solubility.

Acoustic and Elastic Properties of the Southeastern Yellow Sea Mud, Korea

  • Kim, Gil-Young
    • The Journal of the Acoustical Society of Korea
    • /
    • v.25 no.2E
    • /
    • pp.49-55
    • /
    • 2006
  • Compressional wave velocity (Vp), shear wave velocity (Vs), elastic and physical properties, and electrical resistivity for two core sediments obtained from Southeastern Yellow Sea Mud (SEYSM) were measured and computed. The sediments consist of homogeneous mud (mostly silt and clay) with shells and shell fragments. As a result, the mean grain size is uniform ($7.5-8.5{\Phi}$ throughout the core sediments. However, physical properties such as wet bulk density and porosity show slightly increasing and decreasing patterns with depth, compared to the mean grain size. The compressional (about 1475 m/s in average) and shear wave (about 60 m/s in average) velocities with depth accurately reflect the pattern of wet bulk density and porosity. Electrical resistivity is more closely correlated with compressional wave velocity than physical properties. The computed Vp/Vs and Poisson's ratios are relatively higher (more than 10) and lower (approximately 0.002) than Hamilton's (1979) data, respectively, suggesting the typical characteristics of soft and fully water-saturated marine sediments. Thus, the Vp/Vs ratio in soft and unconsolidated sediments is not likely sufficient to examine lithology and sediment properties. Relationships between the elastic constant and physical properties are correlated well. The elastic constants (Poisson's ratio, bulk modulus, shear modulus) given in this paper can be used to characterize soft marine sediments saturated with seawater.

Improvement of Well Efficiency through Well Development in a Pumping Well (충적층 양수정에서 우물개량을 통한 우물효율의 개선)

  • Kim, Gyoo-Bum;Kim, Byung-Woo;Kim, Sung-Yun
    • Journal of Soil and Groundwater Environment
    • /
    • v.15 no.1
    • /
    • pp.39-49
    • /
    • 2010
  • Drilling at unconsolidated layer can make the aquifer disturbed and reduce a productivity of groundwater well. Surge block and air surging were applied to a pumping well located in Jeungsan-ri, Changnyung-gun, to improve a well efficiency by removing clogging and fine-grained slime. Two experimental log-linear equations, $y_1=-0.1769\;ln(x_1)+0.4960$ and $y_2=-84.3358\;ln(x_2)+512.8162$, were proposed in this site, in which $x_1$ and $x_2$ are the number of surging event, $y_1$ is the amount of slime, and $y_2$ is a recovery time of groundwater level after air surging. Well loss exponent (P) decreased after surging, from 3.422 to 1.439, and the groundwater inflow from aquifer happened in all directions around a well with gradually increasing the homogeneity in a local aquifer's hydraulic property. It was revealed that long-term well development should be done in the pumping well which is located in unconsolidated sediments to increase a well productivity.