• Computers and Concrete
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• 제7권2호
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• pp.191-202
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• 2010

A laboratory investigation was conducted to characterize the constitutive property behavior of Cor-Tuf, an ultra-high-performance composite concrete. Mechanical property tests (hydrostatic compression, unconfined compression (UC), triaxial compression (TXC), unconfined direct pull (DP), uniaxial strain, and uniaxial-strain-load/constant-volumetric-strain tests) were performed on specimens prepared from concrete mixtures with and without steel fibers. From the UC and TXC test results, compression failure surfaces were developed for both sets of specimens. Both failure surfaces exhibited a continuous increase in maximum principal stress difference with increasing confining stress. The DP tests results determined the unconfined tensile strengths of the two mixtures. The tensile strength of each mixture was less than the generally assumed tensile strength for conventional strength concrete, which is 10 percent of the unconfined compressive strength. Both concretes behaved similarly, but Cor-Tuf with steel fibers exhibited slightly greater strength with increased confining pressure, and Cor-Tuf without steel fibers displayed slightly greater compressibility.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.7-23
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• 2007

The shear wave velocity is directly related to the deformation characteristic of soils which is an engineering property represented by the shear modulus. This feature presents an opportunity of advantageous utilization of the shear wave velocity for deformation analysis in geotechnical engineering applications, since the deformation modulus is determined on strong theoretical basis, whereas penetration resistances such as N by SPT or qc by CPT rely on empirical relations. Furthermore, it is an engineering property that can be evaluated by performing the same basic measurement in the laboratory and field, and various problems in geotechnical engineering can be dealt with economically and reliably when the field and laboratory methods are combined effectively. In this article, assessment of nonlinear deformation characteristic of soils based on synergic use of the field and laboratory test results is described, and representative case histories of geotechnical applications of the shear wave velocity are illustrated.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.243-246
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• 2009

Localized rainfall due to abnormal climate has caused extensive damages killing several tens to hundreds of people for yearly basis. The typhoon 'Lusa' of year 2002 has resulted 5,400 billion won of property damage and the damages for roads were approximated to be 2,860 billion won at 12,377 locations holding 53% damage of total. The recent typhoon, 'Aewinia' of yeat 2006 caused the 1,400 billion-won property damage including sweeping and flooding of 127 roads and 65 rivers, respectively. There are needs to minimize the damages for important structures for repeated heavy rainfalls every year and, especially, because debris flow might be a main cause of road damage, the design criteria and guideline for roads are required to be improved. Therefore, this paper presented design method of debris-flow control structure for road protection.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1996년도 가을 학술발표회 논문집
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• pp.115-122
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• 1996

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.151-151
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• 2011

Large amounts of natural gas, mainly methane, in the form of hydrates are stored on continental margins. When gas hydrates are dissociated by any environmental trigger, generation of excess pore pressure due to released free gas may cause sediment deformation and weakening. Hence, damage on offshore structures or submarine landslide can occur by gas hydrate dissociation. Therefore, geotechnical stability of gas hydrate bearing sediments is in need to be securely assessed. However, geotechnical characteristics of gas hydrates bearing sediments including small-strain elastic moduli have been poorly identified. Synthesizing gas hydrate in natural seabed sediment specimen, which is mainly composed of silty-to-clayey soils, has been hardly attempted due to their low permeability. Moreover, it has been known that hydrate loci in pore spaces and heterogeneity of hydrate growth in specimen scale play a critical role in determining physical properties of hydrate bearing sediments. In the presented study, we synthesized gas hydrate containing sediments in an instrumented oedometric cell. Geotechnical and geophysical properties of gas hydrate bearing sediments including compressibility, small-strain elastic moduli, elastic wave, and electrical resistivity are determined by wave-based techniques during loading and unloading processes. Significant changes in volume change, elastic wave, and electrical resistivity have been observed during formation and dissociation of gas hydrate. Experimental results and analyses reveal that geotechnical properties of gas hydrates bearing sediments are highly governed by hydrate saturation, effective stress, void ratio, and soil types as well as morphological feature of hydrate formation in sediments.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 지반조사 세미나
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• pp.69-106
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• 1999

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1399-1406
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• 2009

Probability distribution of geotechnical properties is very useful information and it is used for evaluating the geotechnical properties itself and calculating probability of failure. In this study, probability distribution of compression index, recompression index, and void ratio are evaluated, and analysis results show that all property distributions satisfy normal and log-normal distribution.

• 한국지반공학회논문집
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• 제33권12호
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• pp.127-139
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• 2017

고양 지역의 화강 풍화암 지층을 대상으로 시추조사 및 다양한 현장 시추공 시험(프레셔미터시험, 공내전단시험, Downhole test, Suspension PS 검층, 밀도검층)을 수행하였고, 채취한 풍화암 코어시료에 대한 X선 형광분석을 실시하여 풍화도를 평가하였다. 현장 시추공 시험 결과로부터 변형계수, 전단강도 정수, 전단파 속도 등을 평가하였고, 심도에 따라 각 지반특성 값이 증가하는 경향을 확인하였다. X선 형광분석을 통해 산정한 화학적 풍화지수는 심도에 따라 풍화도가 감소하는 일반적인 경향을 나타냈으며, 대표적 풍화지수인 VR과 풍화암의 지반특성과의 관계를 분석하였다.

• Geomechanics and Engineering
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• 제21권1호
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• pp.63-71
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• 2020

Strength anisotropy is a typical feature of thin-bedded rock masses and their strength will be degraded subjected to water immersion effect. Such effect is crucial for the operation of hydropower plant because the impoundment lifts the water level of upstream reservoir and causes the rock mass of nearby slopes saturated. So far, researches regarding mechanical property of natural thin-bedded rock masses and their strength variation under water immersion based on field test method are rarely reported. This paper focuses on a thin-bedded stratified rock mass and carries out field test to investigate the mechanical property and strength variation characteristics. The field test is highlighted by samples which have a large shear dimension of 0.5 m*0.5 m, representing a more realistic in-situ situation than small size specimen. The test results confirm the anisotropic nature of the concerned rock mass, whose shear strength of host rocks is significantly larger than that of bedding planes. Further, the comparison of shear strength parameters of the thin-bedded rock mass under natural and saturated conditions show that for both host rocks and bedding planes, the decreasing extent of cohesion values are larger than friction values. The quantitative results are then adopted to analyze the influence of reservoir impoundment of a hydropower plant on the surrounding rock mass stability of diversion tunnels which are located in the nearby slope bank. It is evaluated that after reservoir impoundment, the strength degradation induced incremental deformations of surrounding rock mass of diversion tunnels are small and the stresses in lining structure are acceptable. It is therefore concluded that the influences of impoundment are small and the stability of diversion tunnels can be still achieved. The finings regarding field test method and its results, as well as the numerical evaluation conclusions are hoped to provide references for rock projects with similar concerns.

• Geomechanics and Engineering
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• 제16권2호
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• pp.125-140
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• 2018

Tianjin, which is located on the west shore of the Bohai Sea, is part of China's Circum-Bohai-Sea Region, where very weak clay is deposited. From the 1970s to the early $21^{st}$ century, Tianjin marine clay deposits have been the subject of numerous geotechnical investigations. Because of these deposits' geological complexity, great depositional thickness, high water content, large void ratio, excessive settlement, and low shear strength, the geotechnical properties of Tianjin marine clay need to be summarized and evaluated based on various in situ and laboratory tests so that Tianjin can safely and economically sustain more infrastructure in the coming decades. In this study, the properties of Tianjin marine clay, especially its consolidation properties, are summarized, evaluated and discussed. The focus is on establishing correlations between the geotechnical property indexes and mechanical parameters of Tianjin marine clay. These correlations include the correlations between the water content and the void ratio, the depth and the undrained shear strength, the liquid limit and the compression index, the tip resistance and the constrained modulus, the plasticity index and the ratio of undrained shear strength and the preconsolidation pressure. In addition, the primary consolidation properties of Tianjin marine clay, such as the intrinsic compression line (ICL), sedimentation compression line (SCL), compression index, $C_c$, coefficient of consolidation, $C_v$, and hydraulic conductivity change index, $C_{kv}$, are evaluated and discussed. A secondary consolidation property, i.e., the secondary compression index, $C_a$, is also investigated, and the results show that the ratio of $C_a/C_c$ for Tianjin marine clay can be used to calculate $C_a$ in secondary consolidation settlement predictions.