• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.10a
• /
• pp.577-584
• /
• 2002

We have employed two methods to remove slime at the end of the sampler in clay layers. The first method is a sampling process that harnesses low pressure to clean up the ground around the sampler tip. The second method, in consideration of a disturbed layer, involves a technique of inserting the sampler 50 cm deep into the ground before cleaning up the verge of the sampler by using high pressure. Physical and mechanical properties of these two methods have been compared and analyzed to investigate how different sampling methods affect degree of disturbance. The first method shows little disturbance since the unconfined compression test results in quite greater E$\_$50//q$\_$u/ in the first method than in the second method. On the other hand, the consolidation test results in a slightly greater compression index in the second method than in the first method, when their indexes are compared in the same depth. This suggests that the second method demonstrates less disturbance than the first method does. It is assumed that the second method may reduce disturbance slightly, However, we suspect that choosing any of the two methods would not obtain a considerable difference in sampling.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.762-765
• /
• 2008

Shotcrete is NATM technique after tunnel excavation as major tunnel support for ground stability, curtail of execution period and reduction of execution expenses instead of general lining method. It is trend using constantly shotcrete lining. This high-strength shotcrete is require to use as constantly shotcrete lining. This brought out the solution of environmental pollution and harmfulness about human. Accordingly, in this study Specimens of strength measurement was made to develop shotcrete possible to develop in early materials with Cement Mineral Accelerator as NATM method construction. It's compared with existing shotcrete material, Unconfined Compression test, flexural strength test were experimented. The fish poison test was experimented to evaluate an influence of environment. On results of test, Unconfined Compressive Strength and flexural strength was equivalent with 28-day strength of existing material. On results of fish poison evaluation research subject material was founded environmentally friendly for existing shotcrete.

• Journal of Ocean Engineering and Technology
• /
• v.22 no.4
• /
• pp.51-58
• /
• 2008

The objective of this study was to investigate the mechanical characteristics of fiber-reinforced lightweight soil using waste fishing net or monofilament for recycling both dredged soils and bottom ash. Reinforced lightweight soil consists of dredged soil, cement, air foam, and bottom ash. Waste fishing net or monoiament was added the mixture in order to increase the shear strength of the lightweight soil. Test specimens were fabricated with various mixing conditions, including waste fishing net content and monofilament content. Several series of unconfined compression tests and direct shear tests were carried out. From the experimental results, it was found that the unconfined compressive strength, as well as the stress-strain behavior of reinforced lightweight soil was strongly influenced by mixing conditions. In this study, the maximum increase in shear strength was obtained with either a 0.5% content of monofilament or 0.25% waste fishing net. The unconfined compressive strength of reinforced lightweight soil with monofilament was greater than that of reinforced lightweight soil with waste fishing net.

• Journal of the Korean Geotechnical Society
• /
• v.27 no.8
• /
• pp.31-37
• /
• 2011

In order to evaluate the effect of matric suction on the strength and deformation characteristics, the unsaturated unconfined compression test is performed for the statical1y compacted silty sand. Specimens used were made under conditions with various initial degrees of saturation. The initial matric suction, matric suction at the peak shear strength and the volumetric deformation during the shear process were measured. From these results, it was found that the initial degree of saturation exerts the influence on the behaviors of suction, peak shear strength and the volumetric deformation. Furthermore, the suction stress($P_s$) which means the apparent cohesion due to matric suction in the unsaturated shear strength could be derived.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.5C
• /
• pp.183-190
• /
• 2009

It is necessary to predict the deformation and stresses on soils to establish the nonlinear stress-strain relationship of geomaterials at various strain levels. Especially, a need exists to establish the pre-failure nonlinear characteristic of cemented granular geomaterials used in road constructions. In this paper, therefore, conventional granular soils were mixed with various cementing materials, such as cement and fly ash from coal combustion by-products. Then, the normalized nonlinear behavior of cemented geomaterials was assessed using unconfined compression test. In addition, various constitutive models of soils were evaluated for estimating pre-failure non-linear behavior of cemented geomaterials from the test results.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.22 no.3
• /
• pp.60-74
• /
• 1980

Soil-cement mixtures involve problems in it's durability in grain size distribution and mineral composition of the used soils as well as in cement content, compaction energy, molding water content, and curing. As an attempt to solve the problems associated with durability of weathered granite soil with cement treated was investigated by conducting tests such as unconfined compression test, it's moisture, immers, wet-dry and freeze-thaw curing, mesurement of loss of weight with wet-dry and freeze-thaw by KS F criteria and CBR test with moisture curing on the five soil samples different in weathering and mineral composition. The experimental results are summarized as follows; The unconfined compressive strength was higher in moisture curing rather than in the immers and wet-dry, while it was lowest in freeze-thaw. Decreasing ratio of unconfined compressive strength in soil-cement mixtures were lowest in optimum moisture content or in the dry side rather than optimum moisture content with freeze-thaw. The highly significant ceofficient was obtained between the cement content and loss of weight with freeze-thaw and wet-dry. It was possible to obtain the durability of soil-cement mixtures, as the materials of base for roads, containing above 4 % of cement content, above 3Okg/cm$_2$ of unconfined compressive trength with seven days moisture curing or 12 cycle of freeze-thaw after it, above 100% of relative unconfined compressive strength, 80% of index of resistance, below 14% of loss of weight with 12 cycle of wet-dry and above 1. 80g/cm$_2$ of dry density.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.10a
• /
• pp.263-270
• /
• 1999

In country, for 2002 World-cup the peak is to construct soccer playground. the stabilizing method by additives is mainly applied of permanent improvement for bearing capacity of structure foundation and for strength, durability and transformation of road pavement layer except for construction machine's trafficability and bearing capacity. This study is on soft ground improvement of $\bigcirc$$\bigcirc$ world-cup stadium field. construction field constitutes of very various layers and after construction the lawn grass should be planted on the surface of the earth and in addition, chemical effects should be limited from improved ground layer. Mixing soft clay in field with three domestic representative additives, it evaluated the unconfined compression strength. In the results, after curing during 28 days the objective strength has been obtained on about 5% combination ratio.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.45 no.6
• /
• pp.144-152
• /
• 2003

Laboratory experiments were carried out to investigate the influence of pore water contamination on the treatment effect of sandy soil which was solidified by Portland cement. In the experiments, setting time of hydraulic cement that was mixed with contaminated mixing water was measured using Vicat equipment and observed the tendency of setting process with the kind of contaminants, organic or inorganic components. It was shown that organic contaminants of the mixing water affect largely on the initial setting process of hydraulic cement and inorganics, expecially heavy metals, did not affect on the initial setting process, otherwise it was appeared that setting time of the sandy soil that was contaminated with inorganic components was apparently faster than the sandy soil that did not include inorganic components even though organic concentrations was relatively low level (COD=200∼300) in the mixing water. The results of unconfined compression strength test (UCST) were well consistent with the results of Vicat equipment test.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.1004-1011
• /
• 2008

In this study, obtained large block sample and piston sample of marine clay in korea were performed unconfined compression and consolidation test. Soil properties of two type samples such as failure strain, between two parameter's ratio($E_{50}$ and $q_u$), and volumetric strain were used to evaluate sample disturbance. The result, large block samples show a low disturbance than piston samples. Therefore, we suggest new sample disturbance evaluated method through the relation of OCR and volumaric strain at shallow of marine clay in Korea and suggest new sample disturbance classified method by subdivided grade for failure strain of unconfined compression test.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.353-360
• /
• 2000

We developed large diameter sampler (we called KICT type large diameter sampler) to obtain undisturbed clay and sand samples. In-situ test carried out in the In-Chon international airport and Kim-Hae. Also we obtained undisturbed sample with a hydraulic piston sampler in the nearly site and carried out unconfined compression test, consolidation test and triaxial test. The result, unconfined compression strength, secant modules, preconsolidation pressure and undrained shear strength of samples to obtain KICT type large diameter sampler are larger than that of samples to obtain hydraulic piston sampler. But failure strains and volume changes at the consolidation of samples to obtain KICT type large diameter sampler are smaller than that of samples to obtain hydraulic piston sampler