• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.32-37
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• 2010

Recently, the land area for many people has been limited because of industrialization and modernization in Korea. The large-scale constructions like the reclamation development projects have been progressed to resolve this problem mentioned above. Therefore, as many of the usefulconstruction materials as possible are needed to perform the large-scale construction projects. Many studies for the utilization of pond ash which has a similar characteristic of sand have been conducted and there has been often occurred many structural problems on roadbed in winter. Therefore, the characteristics of the freezing and thawing for Controlled Low-Strength Material (CLSM) using pond ash were analyzed and evaluated by unconfined compressive strength test in this study. As a result of this study, it was confirmed that new CLSM using pond ash with cement (8.2% by weight)was able to stand for the freezing and thawing behavior.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.53-60
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• 2010

The natural soils are classified in saturated soils and unsaturated soils according to level of ground water but the research for only saturated soils has been conducted by this time. However, there are many proble.ms which are not solved by using the concept and principle of saturated soils on the natural soils. In fact, it is known that unsaturated soils represent the behavior characteristic unlike completely saturated soils because of the adhesion under the influence of negative pore water pressure, the high angle of friction and the low water permeability by the air entry. So it needs to conduct the various researches on insufficient unsaturated soils. In this paper, unsaturated triaxial compressive tests are conducted in order to do research on shear strength characteristic on sands and silty sands of Nakdong river. As a result of the tests, the cohesion is increased in non-linear type according to the change of the matric suction, but the angle of internal friction is not changed much.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.434-443
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• 2009

Slope stability analysis is an essential part of rock slope design. For highly fractured rock, the limit equilibrium method (LEM) based slope stability analysis with a circular failure surface is often carried out assuming the rock mass behaves more or less as a continuum. This paper examines first, the applicability of the finite-element method (FEM) based shear strength reduction (SSR) technique for highly fractured rock slope, and second the use of Mohr-Coulomb (MC) failure criterion in conjunction with generalized Hoek-Brown (HB) failure criterion. The numerical results on a number of cases are compared in terms of the factor of safety (FS). The results indicated that the FEM-based SSR technique yields almost the same FSs from LEM, and that the MC and HB failure criteria yield almost identical FSs when the strength parameters for MC failure criterion are obtained based on the modified HB failure criterion if and only if value of the Hoek-Brown constant $m_i$ is smaller than 10 and slope angle is smaller than 1:1, otherwise MC failure criteria over-estimate the factor of safety.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.341-348
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• 2009

Various types of micro cone penetrometers have been developed by using strain gages for the layered soil detection. Strain gages, however, are affected by several factors such as temperature, self heating and lead wire length. In this study, micro cone penetrometers with 3~7mm in diameter, are developed by using FBG sensor to overcome the defects of the strain gage, and compensate the effect of temperature during penetration. In order to verifiy the accuracy and reliability of the developed FBG cone, the cone penetration test is performed on the layered soil. The tip resistance of FBG snesor shows excellent sensitivity, and can detect the interface of the layered soils with higher resolution. In addition, the 3mm micro cone penetrometer which is impossible cone diameter by using strain gages presents much higher sensitivity than the 7mm cone penetrometer. This study suggests that FBG sensor is a useful sensor for manufaturing the ultra small sized cone, and effectively detects the interface of the layered soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1107-1112
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• 2009

Ground anchor should not be used in soft clay, because anchor resistance can not be guaranteed. However, there is a way to increase the capacity of anchors. The pulse powered anchor is an underreamed anchor by using high voltage electrokinetic pulse energy. In this study, a series of field test were carried out in order to find expansion rate related in number of pulse charge. and Anchor pull-out tests were performed at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea. Data were analyzed in order to define a relation between expansion rate and ultimate pullout load.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1183-1189
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• 2009

The sedimentation rate of particles in a suspension is a function of particle size, initial slurry water content and salinity. Many researches conducted on the behavior of dredged soils have centered on such factors. However, there have been few attempts to assess another important influence factor of seasonal water temperature on designing the placement of dredged materials. In this paper, the effect of seasonal water temperature on sedimentation characteristics of dredged clay was investigated with consideration of three different water temperatures, that are $5^{\circ}C$, $15^{\circ}C$, $35^{\circ}C$, which represent critical water temperatures in winter, spring or fall, and summer, respectively. A series of experimental results reveal that the sedimentation rates for the water temperature of $15^{\circ}C$ and $35^{\circ}C$ are very similar each other, but that of $5^{\circ}C$ that represents a winter season leads to a considerably delayed sedimentation compared to the others. This may be attributable to the retardation of ion-leaching from clay particles at low water temperature.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.634-639
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• 2009

The response displacement method is the most frequently used method for the seismic design of underground structures. Underground structures under seismic loading will tend to deform with the surrounding ground, and thus the structure is designed to accommodate the free-field deformation without loss of its structural integrity. This method is pseudo-static method, and response displacement of surrounding ground are most important steps. In this study, the single cosine method and the equivalent linear analysis are applied to estimate the response displacement of the real sites, and the results of the each method are compared. Response analysis was also performed with respect to bedrock depth. As a results, Equivalent linear analysis result was larger than single cosine method. And, the relative displacement becomes lager according to depth of the bedrock.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.993-998
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• 2009

This study was conducted to propose the model that is able to predict long-term settlement of sands containing carbonates. We can observe that in addition to the initial elastic compression, a considerable additional compression occurs with long-term period in some sands. The compressibility of sands is significantly dependent on particle characteristics. Some sands have many pores and particularly has an angular shape. To predict of long-term settlement of these sands which contain carbonates, first of all a variety of tests which are to assess chemical, physical and compression characteristics of these sands were conducted. Second, in order to know settlement with time, the time parameter was determined by analyzing the measured data obtained from $\bigcirc\bigcirc$ area. The measured settlement of this area shows that in addition to the initial elastic compression, a considerable additional compression occurring with time. It was caused by the crushing, shattering, and rearrangement of particles, which were real phenomena in sandy soils under loading condition. Based on this case study, we proposed that a simple method is able to predict settlement with time of sandy soil containing carbonates.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.30-37
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• 2009

In doing the foundation work in the downtown, the popular complaints by means of Noise and vibration have been became heavy burden. Therefore, the noise & vibration-free screw PHC pile method will contribute to the foundation work by removal of the popular complaints and improvement of the constructability. In this paper, the load bearing capacity and displacement characteristics of the noise & vibration-free screw PHC pile were analyzed. The noise & vibration-free screw PHC pile's behavior was better well than the existing PHC pile's one.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1113-1124
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• 2009

The limit equilibrium method and finite element method have been commonly used to assess the stability of anchored slope. However, the existing limit equilibrium methods do not consider the load transfer of anchor and, if the potential failure surface crosses the bonded zone of anchors, the anchor loads are not included in computing the factor of safety. In this paper, simplified bishop method, one among several methods based on the limit equilibrium is used to develope the Excel Sheet program and the working load of anchor along the failure surface is calculated by Flamant's formula, proposed by Morlier and Tenier(1982). Additionally, the finite element analysis of anchored slope considering the load transfer is performed in order to compare with the result from the limit equilibrium analysis and analyze the reinforced effect of anchor. From this study, new modelling method that limits the reinforcing range and considers the load transfer is proposed and Excel Sheet program is developed. The factor of safety for several cases between PC STABL and Excel Sheet program is also compared for verification of the program.