• 산업기술연구
• /
• 제20권A호
• /
• pp.113-122
• /
• 2000

Column tests in the laboratory were preformed to investigate characteristics of settling process of dredged soil sampled from in-situ. Test results were analyzed by using the existing theories on discrete settling and hindered settling. From column tests of monitoring the interface with time, settling was found to be a linear process with time and the settling rate was increased with initial water content of slurry. The settling rate was also observed to decrease with increasing initial height of slurry. Most of settling process were composed of flocculation, hindered settling and self-weight consolidation. On the other hands, flocculation of soil during settling was observed and it was found that the size and density of flocculated particles could be analyzed by using the method proposed by Richardson and Zaki.

• 한국농공학회지
• /
• 제45권1호
• /
• pp.63-73
• /
• 2003

The settling of the dredged soil may vary with mineral composition, grain size distribution, initial water content and salt concentration of suspension of the site. A series of settling column test was performed to investigate the behaviour of solid suspension material from dredging and reclamation. Settling mode was divided into four types from the observation of interface and settling curves of clay minerals and marine clay samples, and the relationship charts of salt concentration and the initial water content were established to use in the dredging operation with any salt concentration. The critical initial water content which was defined as a threshold of zone settling and the consolidation settling was varied with salt concentration of water and was proportional to the plasticity of soil in sea water.

• 상하수도학회지
• /
• 제22권6호
• /
• pp.627-632
• /
• 2008

It is necessary to investigate methods for improvement by diagnosing sludge settling characteristics on inflow of slurry to thickener. The results of the settling tests are correlated to determine zone settling velocities at the various sludge solids concentrations. Conditioning of WTP residuals is generally done by either chemical or physical treatment. The settling test was conducted with 1m columns dosing polymer to WTP residuals at various solids concentration. The estimated results for dosing to WTP residuals for a sludge of 2,100 ~ 16,012 mg/L solids concentration were the zone settling velocities of 48.38 ~ 6.8 m/day, supernatant solid concentration of 3.2 ~ 19 mg/L and solid flux of $101.6{\sim}317.61kg/m^3{\cdot}day$. The values for non-polymer treatment were the zone settling velocities of 28.37 ~ 0.12 m/day, supernatent solid concentration of 8.5 ~ 108 mg/L and solid flux of $59.58{\sim}1.92kg/m^2{\cdot}day$. The limiting solid flux value by Yoshioka methods was $4.0kg\;TS/m^3{\cdot}day$ for Non-polymer and $228.0kg\;TS/m^3{\cdot}day$ for dosing polymer. These results are to indicate a possibility of improvement on the thickening characteristics and the quality of supernatant as increasing the settling velocities by dosing polymer to WTP residuals.

• 한국농공학회논문집
• /
• 제47권1호
• /
• pp.51-59
• /
• 2005

The settling rate of the dredged soil may vary with mineral composition, grain size distribution, initial con contration and salt concentration of suspension of the site. A series of settling column test was performed to investigate the settling rate characteristics of solid suspension material from dredging and reclamation. The settling rate of soil mixed with various size of particles depended on clay fraction which showed a inherent flux. A model was developed to predict the particle flux of mixed soil from the clay flux and its applicability was verified.

• 한국해안해양공학회지
• /
• 제18권3호
• /
• pp.179-188
• /
• 2006

본 연구의 목적은 시화호 점착성 퇴적물의 침강 및 침식특성을 정량적으로 분석하는 것이다. 침강특성은 특수 제작된 1.8 m의 침강수주를 이용하여 multi-depth 부유사 농도 채취방법으로 수행하였고, 침식특성은 전북대 환형수조를 이용하여 각기 다른 밀도를 갖는 균일저면 조건하에서 수행하였다. 침강실험의 결과로서, 시화호 점착성 퇴적물은 부유사 농도값이 0.1$0.002의 침강속도 값을 갖는 것으로 확인되었다. 또한, 침식실험의 결과로서 저면밀도를 $1.14{\sim}1.32g/cm^{3}$로 변화 시켰을때, 침식한계전단응력은 $0.19{\sim}0.55N/m^{2}$으로 증가하였으며, 침식률계수는 $18.4{\sim}3.9mg/cm^{2}{\cdot}hr$의 범위로 감소하였다.

• 산업기술연구
• /
• 제24권A호
• /
• pp.251-261
• /
• 2004

A series of column test with a silty marine soil mixed with Jumunjin Standard Sand were performed to investigate the characteristics of settling and consolidation of non-plastic dredged soils. Column tests were carried out by using the separable column to measure the grain size distribution of consolidated layer. Column tests were performed with changing the mixing ratio of Jumunjin Standard Sand to the silty marine soil, initial water content of slurry and initial height of slurry. Height of interface of slurry was monitored during tests and grain size distribution tests were carried out after finishing tests. Influencing factors on the particle segregation, eventually to the characteristics of settling and consolidation of non-plastic soil, were analyzed on the thesis of test results. As results of column tests, the mixing ratio of sand to the silty marine soil and the initial water content of slurry were known to affect the characteristics of settling and consolidation resulted in significant particle segregation of slurry. Initial height of slurry was found not to affect seriously to particle segregation.

• 대한환경공학회지
• /
• 제38권4호
• /
• pp.210-218
• /
• 2016

대전의 관평천에 설치된 1.8 m 높이의 침강 실험장치를 이용하여 총 4회에 걸쳐 강우 유출수를 채취하여 오염물질제거 효율 및 특성을 측정하였다. 오염물질 농도는 초기 4시간 동안 급격하게 감소하였으며 약 24시간 후 일정한 수준을 나타내는 경향을 보였다. 침전 실험 장치 내에서는 높이 별 농도가 크게 다르지 않은 것으로 관찰되었으며 이는 침전장치 내에서 대부분의 고형물질은 서로 방해하지 않고 독립적으로 침전하기 때문인 것으로 분석된다. 강우 유출수를 대상으로 분석한 입도는 $10{\sim}100{\mu}m$의 범위로 나타났다. 강우 유출수내에서 TP의 경우 입자성 물질이 평균 52.4%, TN의 경우 23.5%의 비율로 나타났으며 TN의 경우 침강에 의해 효율적으로 제거되기 어렵다는 것을 확인하여 주고 있다. 본 연구의 결과는 초기 강우 유출수에 포함되어 있는 TSS와 TP와 같은 오염물질이 단순한 침강에 의해 효과적으로의 제거될 수 있다는 것을 나타내고 있으며 하천수질을 보호하는데 적극적으로 활용될 수 있음을 시사한다.

• 한국지반환경공학회 논문집
• /
• 제12권5호
• /
• pp.29-36
• /
• 2011

본 연구에서는 침강압밀특성을 분석하기 위하여 준설투기가 예상되는 대표시료 중 점성토와 사질토를 대상으로 침강시험을 실시하였다. 분석결과 침강압밀계수($C_s$), 함수비와 계면고의 관계에서 점성토와 사질토는 뚜렷한 차이를 보이고 있다. 그러나 준설매립 직후 초기 체적변화 예측결과 점성토에서는 시간에 따른 함수비변화가 급감하였으나 사질토층에서 함수비변화에 따른 차이를 보이지 않았다. 또한 본 실험에서 적용한 실험조건에 대한 타당성 검토를 위해 실질토량고에 따른 침강압밀계수와 초기침강 속도를 분석한 결과 실험조건은 적정한 것으로 판단되며, 이와 같은 분석으로 재료 각각에 대하여 압밀침강특성치의 범위와 평균 및 대표적인 관계식을 제안하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1992년도 가을학술발표회 논문집
• /
• pp.55-60
• /
• 1992

Hydraulically filled ground is formed by the settling of soil grains from the mixture of soil grains and water. It was generally known that the settling speed of the soil grains in governed by Stokes low. In the case of clayed dredged material, the shape of soil grains is not round, the surface of the soil grains is relatively large compared to the weight of soil grains and inter-grain ionic force is relatively large compared to the wight of soil grains. By this reason the settling and consolidation behavior of hydraulically filled quite different from that of Stokes law. This study investigated the settling and consolidation behavior of hydraulically filled materials of Yeochon industrial complex by large scale laboratory settling & consolidation container. The test results showed tat actual settling speed of soil grains in quite large compared to that of Stokes law. It was turned out that this phenomenon was due to the aggregation of soil grains. Also, it was truned out that the void ration and water content after the completion of settling process was 8.7 and 322% respectively. The consolidtion settlement of clayey hydraulic fill material was predicated better by "incremental small strain" consolidation concept than classical Terzaghj's consolidation concept (infinitesimal strain).

• 한국물환경학회지
• /
• 제21권3호
• /
• pp.230-235
• /
• 2005

The main purpose of the flocculation process is to make flocs bigger to be removed easily in the following processes. The flow pattern and mixing intensity have a great influence on flocculation. In this study, the flow pattern was examined by a hydraulic tracer-test, where 3 water treatment plants having $800,000m^3/d$, $44,000m^3/d$ and $40,000m^3/d$ were employed. Also, the settling test was conducted to find out the relationship between the mixing intensity and the settling ability of flocs. The hydraulic tracer-test was conducted for the various flocculation processes that have different structures of flocculation basins. In the result, the retention time distribution (RTD) curves for the flocculation processes were quite different. In case of the inappropriate structure of the flocculation basin, the flow is not even so that the floc does not grow enough. To find out the relationship between mixing intensity and settleability of flocs, G-values were calculated and the settling test was conducted for two flocculation basins which have the same conditions except the G-value. For the flocculation basin with uneven G-value, the floc settleability was revealed poor. On the other hand, the flocculation basin with even G-value, the settleability was better than the previous one. From these experimental results, it is confirmed that the flow pattern is closely related to the structure of the flocculation basin and the settleability is affected by mixing intensity. Therefore the flow pattern and the strength of the mixing intensity should be examined sufficiently to design and operate flocculation basin.