• Magazine of the Korean Society of Agricultural Engineers
• /
• v.34 no.4
• /
• pp.48-58
• /
• 1992

This study was conducted to investigate the consolidation characteristics of the marine clay, treated with predetermined ratios of lime and briquette ash. The standard consolidation test was performed for the sample of mixture remoulded under the condition of optimum moisture content. The results obtained were as follows ; 1.The increase of the consolidation coefficient due to load increament was larger in the lime treated soil and briquette ash treated soil than in the untreated soil. The decrease of the compression index due to admixing ratio of additives was smaller in the former than in the latter. 2.The increase of the secondary consolidation coefficient of the untreated soil due to load increment was minimal, while that of lime treated soil and the lime-briquette ash treated soil was conspicuous and that of briquette ash treated soil was slight. 3.The $C\alpha$/Cc relationship of untreated soil was represented by colsely distributed points. That of briquette ash treated soil, lime treated soil and the lime-briquette ash treated soil was represented by linear distribution. The $C\alpha$/Cc values of untreated soil, briquette ash treated soil and lime treated soil were approximately 0.049, 0.044 and 0.031, respectively. 4.The maximum consolidation coefficient was obtained with lime and briquette ash (lime : briquette .h 2 :1) mixture ratio of 15%. And the minimum secondary consolidation coefficient, compression index was obtained with same mixture ratio. The required quantity of lime could be reduced and the consolidation was accelerated by applying the above mixture ratio.

• Korean Journal of Agricultural Science
• /
• v.10 no.1
• /
• pp.110-117
• /
• 1983

This study was conducted to investigate the influence of load increment ratio on the secondary consolidation for the marine clay at Asan bay by the hyperbola method. The results were summarized as follow: 1. Calculated secondary consolidation by the hyperbola method was slightly less than the value of Casagrande's log t method, but the difference was very little, and the secondary consolidation could be easily calculated by the hyperbola method even if load increment ratio was small. 2. The secondary consolidation ratio was increased with the decrement of load increment ratio, and the creep phenomenon of the settlement curve occurred under the condition of small load increment ratio seemed to be caused by the secondary consolidation. 3. The secondary consolidation ratio occurred during the primary consolidation was irregular in the overconsolidated range, but it was increased with the decrement of load increment ratio in the normally consolidated range. 4. The coefficient of secondary consolidation was increased with the increment of the consolidation load, made a point of the inflection near preconsolidation. And the coefficient of secondary consolidation was decreased from consolidation load $2kg/cm^2$, showed independent of load increment ratio. 5. The coefficient of secondary consolidation was showed in proportion to compression index.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.16 no.1
• /
• pp.18-26
• /
• 2004

In order to accelerate the rate of consolidation settlement, to reduce settlement, and to increase bearing capacity for soft ground under quay, sand compaction pile method (SCP) has usually been applied. SCP-reinforced ground is composite soil which consists of the sand pile and the surrounding soft soil. One of main important considerations in design and analysis for SCP-reinforced soils is stress concentration ratio according to area replacement ratio. In this paper, the numerical analysis was conducted to investigate characteristics of stress concentration ratio in composite ground. It was found that stress concentration ratio of composite ground is not constant as well as depends on several factors such as area replacement ratio, depth of soft soil, and consolidation process. The values of stress concentration ratio increase during loading stage due to stress transfer of composite soil, and reach up to 2.5∼12 according to area replacement ratio at the end of construction. After the end of consolidation, however, these values are converged to 2.5 to 6.0 irrespective of area replacement ratio due to increase in effective stress of soft soil during consolidation process.

• Geomechanics and Engineering
• /
• v.19 no.5
• /
• pp.447-462
• /
• 2019

The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.

• Geomechanics and Engineering
• /
• v.25 no.2
• /
• pp.159-170
• /
• 2021

Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.

• Geotechnical Engineering
• /
• v.11 no.1
• /
• pp.41-50
• /
• 1995

In situ clay soils with Ko condition have anisotropic characteristics, varying the response according to the principal stress direction upon loading. But because of their practicality and simplicity, consolidated isotropic undrained compression tests are commonly used in practice to determine the behavior of cohesive soils. In this study to investigate the anisotropic characteristics and the effects of consolidation stress states on the response of normally consolidated clay soils during shearing, triaxial compression and extension tests after consolidating the undisturbed clay soil samples, which are obtained as a block sample to normalized consolidation states under isotropic or Ko state, were carried out. As a result of tests, the anisotropy of the undrained strength was confirmed. Comparing the soil responses between isotropic and Ko consolidation, the undrained strength by isotropic consolidation is overestimated because of its higher mean consolidation pressure. And isotropic consolidation reduces the anisotropy of soil response and influences on the stress-strain behavior and pore pressure response because the animotropic soil structure is partially collapsed during isotropic consolidation process. Also, OCR in overconsolidated soils is decreased by isotropic consolidatiorL Friction angle in eztension is higher than that in compression, but regression analysis shows that friction angle with cohesion in extension is almost the same as that without cohesion in compresslon.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.7
• /
• pp.75-80
• /
• 2008

When a saturated clay is sampled in an undisturbed manner from a bore hole, the sample extends vertically and shrinks horizontally under undrained conditions due to stress release. The conventional consolidation test specimen is trimmed from the expanded sample so that its diameter is equal to the inner diameter of the consolidation test ring, and this test procedure does not reproduce the actual consolidation behavior. The measurement of sample extension was conducted by means of overcoring method showed that the extension strains were 1 to 2%. To simulate the in-situ consolidation behavior, we proposed the consolidation test method that uses a specimen with a slightly smaller diameter than the inside diameter of consolidometer so that the specimen expands laterally to the inside of the ring.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2006.11a
• /
• pp.661-664
• /
• 2006

Under a VMI (Vendor Managed Inventory) system, the vendor holds a certain level of control over not only inbound replenishment decisions on stocking but also outbound re-supply decisions. In this situation, vendor faces a better opportunity to synchronize the inventory and transportation decisions. However, shipment consolidation can reduce transportation expenses, but delivery time about the customer comes to be long and a customer service is fallen. Thus, a stock and transportation decision must consider this correlation. This study look into the relevant literature and suggest about further research direction.

• The Korean Journal of Rheology
• /
• v.7 no.1
• /
• pp.42-49
• /
• 1995

항공용 프리프레그의 기체 투과와 creep 변형 현상을 실험과 모델링을 통하여 autoclave 공정의 주요 공정변수인 시간, 온도 그리고 consolidation 압력에 대하여 연구하였 다. 적층된 프리프레그를 이용한 실험을 통하여 진공/autoclave 압력이 프리프레그에 가해졌 을 때 프리프레그의 두께는 선형 점탄성 변형을 나타내며 in-plane 기체 흐름은 투과 hysteresis 와 함께 non-Darcian flow 현상을 나타냄을 보여주었다. 이러한 현상은 bulk dimensional relaxation 그리고 미시적 기공의 구조 재배열이라는 두 가지 점탄성 완화현상 으로 관찰되고 분석되어졌다. Modified Standard Linear Solid (SLS) 점탄성 모델을 사용하 여 실험결과를 분석한 결과 creep relaxation 과 기체투과 속도를 대표하는 모델상수를 결정 할수 있었다.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.1210-1224
• /
• 2009

The present paper illustrates the outcome of the monitoring of the consolidation behavior of a soft foundation soil under a large submerged sand embankment. Measurements of settlements and excess pore water pressures showed a good agreement with predictions evaluated using the large strain consolidation theory. Soft soil improvement by means of deep mixing has been optimized. Moreover, the principles and developments of underwater geosynthetics applications are discussed.