• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.331-340
• /
• 2009

This study evaluates the relationship between cone tip resistance ($q_c$) and small-strain shear modulus ($G_{max}$) of cemented sand. For this purpose, a series of miniature cone penetration and bender element tests are performed in calibration chamber specimens with various gypsum contents. Experimental results show that both $q_c$ and $G_{max}$ of sand increase with increasing cementation level as well as relative density and vertical confining stress. However, the relative density and vertical confining stress has more significant influence on $G_{max}$ and $q_c$ of uncemented sand than those of cemented sand. It is observed that the $G_{max}/q_c$ ratio of cemented sand decreases with increasing relative density. This result means that state variables have more affect on $q_c$ than $G_{max}$ of cemented sand. Test results also show that the effect of vertical stress on $G_{max}-q_c$ relation is reduced by cementation effect.

• Journal of the Korean GEO-environmental Society
• /
• v.7 no.5
• /
• pp.13-20
• /
• 2006

We have conducted standard penetration tests and static cone penetration tests that are widely used the land base examination on the soft ground subsurface of Yongdong area, and examined the correlation between them. We have also made a comparative analysis of the correlation between the indoor tests on the materials collected on the site and on-the-spot penetration tests. The results are as follows : The relationship between Standard Penetration Test N-value and Dutch Cone Tset show $Q_c=1.93N+0.29$ for organic soil, $Q_c=2.19N+0.20$ for clay, $Q_c=2.34N+1.06$ for silt, $Q_c=3.02N+0.54$ for silty sand, and $Q_c=3.47N+0.46$ for sand. In this case of sand $Q_c/N$ increases when the soil particles are larger. The relationship between standard penetration test N-value and Unconfined Compression Strength $q_u$ show $q_u=0.11N+0.03$ for organic soil, $q_u=0.11N+0.25$ for clay, and $q_u=0.18N-0.03$ for silt.

• 기술발표회
• /
• s.2006
• /
• pp.261-269
• /
• 2006

Recently, piezocone penetration test is frequently used in order to estimate the characteristics of soft ground with standard penetration test; generally used in the past In this study, standard penetration test, piezocone penetration test, driving resistance of vertical drain were used in order to increase the confidence for determination of soft ground depth. And the compressible layer was determined by the comparison between the preconsolidation pressure and the designed increase pressure. As the results, the relation between standard penetration test and piezocone penetration test shows $q_c$=(1.09~1.63)N at the soft ground, determined by 5/30 N value. And $q_c$(1.21~1.98)N was shown at the point of compressible layer, evaluated by the preconsolidation pressure. And driving resistance of vertical drain is 70 f/$cm^2$ which is equal to 10kgf/$cm^2$ cone penetration resistance.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.1159-1166
• /
• 2005

In the present study, a series of laboratory tests with sands of different silt contents, are conducted and methods to assess non-linear behaviors based on in-situ test results are proposed. Modified hyperbolic stress-strain model is used to analyze non-linearity of silty sands in terms of non-linear degradation parameters f and g as a function of silt contents and relative density $D_R$. Stress-strain relationship results were obtained from a series of triaxial tests on sands containing different amounts of silt. Initial shear modulus which was applied to normalize modulus degradation of silty sands were determined based on the resonant column test results. From the laboratory test results, it was observed that, as the relative density increases, values of f decrease and those of g increase. Cone resistance $q_c$ for silty soil condition used in the triaxial tests were estimated based on the cavity expansion analysis. A suggestion to make an estimation of degradation parameters f and g as a function of fine contents is addressed in terms of cone resistance $q_c$ .

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.1083-1086
• /
• 2008

In this study, Estimate solutions of ultimate lateral resistances for lateral loaded piles are proposed using cone penetration values, $q_c$ values, as CPT results. Cone penetration values, $q_c$ values measured on clean sand layers, are represented by factors for relative densities, axial stresses, and lateral stresses which are important on analysis of sandy soil layers. Also, these factors are same factors to consider existed estimations of ultimate lateral capacity. In this study, estimation of ultimate lateral capacity for lateral loaded piles using CPT results is proposed, and this estimation is verified by adequate analysis for effective reliability.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.628-635
• /
• 2008

A series of cone penetration tests in large calibration chamber were performed to investigate the effect of cementation level, relative density and vertical confining stress on cone resistance. From the experimental results, it was observed that the cone resistance is increased with increasing gypsum content, relative density, and confining stress. The increasing ratio on cone resistance of cemented sand compared with that of uncemented sand, that is IR($q_c$), was increased with increasing gypsum content and relative density, whereas it was decreased as the vertical confining stress increases. It was also observed that the cementation of granular soil influences the behavior of ground at low level of confining stress and its effect is diminished with depth.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.7
• /
• pp.7-16
• /
• 2010

Stress history increases the residual horizontal stress of granular soil and, consequently, the penetration resistance. This study analyzes the effect of stress history on the cone resistance ($q_c$), horizontal stress index ($K_D$) and dilatometer modulus ($E_D$) of CPT and DMT from calibration chamber specimen in OC as well as NC state. Test results show that the normalized cone resistance by mean effective stress correlates well with the relative density and the state parameter, whereas the normalized cone resistance by vertical effective stress is a little affected by stress history. The influence of stress history is more reflected on $K_D$ than $E_D$ and $q_c$. The $K_D/K_0$, in which the effect of stress history on $K_D$ is compensated by the at-rest coefficient of earth pressure, $K_0$, is related to relative density, state parameter and the normalized cone resistance by mean effective stress. It is also observed that the normalized dilatometer modulus by mean effective stress ($E_D/{\sigma}_m'$) shows a unique correlation with the state parameter, regardless of stress history.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.1407-1414
• /
• 2009

In this study, a Jeju sand, which contains both siliceous and calcareous materials, was sampled from a beach in Jeju Island. It is observed that the Jeju sand has high extreme void ratios due to the angularity of grains and the intra-particle voids of hollow particles. From cone penetration test using calibration chamber system, it is found that the cone tip resistance($q_c$)-relative density(Dr)-vertical effective stress(${\sigma_v}'$) relation of Jeju sand almost matches to that of high compressible quartz sand. However, this correlation overestimates the relative density of a coastal sediments in Jeju Island maybe due to the cementation effect of this area. From analysis of the results of cone penetration and SPS tests at a coastal area in Jeju Island, it seems reasonable to assume that the coast of Jeju Island is a natural cemented sediments.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.11
• /
• pp.71-77
• /
• 2008

In this study, CPT-based methodology for estimating the ultimate lateral resistance, $p_u$, is proposed and verified for lateral loaded piles in sandy soil. Preexistent methods estimating the ultimate lateral resistance, $p_u$, and the ultimate lateral capacity, $H_u$, of pile have been based on the vertical effective stress, relative density, and the coefficient of lateral earth pressure. Similarly, cone resistance $q_c$ in pure sandy soil is expressed by those essential factors. As correlation between $p_u$ and $q_c$ are normalized with average effective stress ${\sigma}_m$, estimation methodology for the lateral loaded pile of $p_u$ in sandy soil is proposed. The method is verified by calibration chamber test results in pure sand. The standard derivation of estimated $p_u$ is 0.279, and COV (Coefficient Of Variation) of estimated $p_u$ is 0.272. These results showed that the estimated pus by the method are analogous with the measured $p_us$ in calibration chamber test.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.701-708
• /
• 2003

Recently, piezocone penetration test is frequently conformed in order to estimate the characteristics of soft ground with standard penetration test, generally used in the past. The soil characteristics, such as cone penetration resistance, friction resistence and excessive pore water pressure, can be evaluated continuously through the piezocone penetration test. In Incheon International Airport 2nd phase site preparation, standard penetration test and piezocone penetration test were used in order to increase the confidence for determination of soft ground depth. And the compressible layer was determined by the comparison between the preconsolidation pressure and the designed increase pressure. As the results, the relation between standard penetration test and piezocone penetration test shows q$_{c}$=(1.09~l.63)N at the soft ground, determined by 5/30 N value. And q$_{c}$=(1.21~l.98)N was shown at the point of compressible layer, evaluated by the preconsolidation pressure. These results were applied to determination for the depth of soft ground and to design the improvement for the soft clay.lay.