Evaluation of Relative Density and Friction Angle Based on SPT-N Values

Hassan Mujtaba,Khalid Farooq,Nagaratnam Sivakugan,Braja M. Das 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.2

This study is an attempt to evaluate relative density and friction angle of sands on the basis of SPT-N values. In order to develop the relationships among relative density (Dr), friction angle (φ ) and SPT-N value, field and laboratory test results from sixty boreholes executed in sandy deposit were used. The field tests include the SPTs conducted in the boreholes and the determination of in-situ density at various depths in the boreholes using the pitcher sampler whereas the laboratory tests include routine classification, direct shear box, maximum and minimum density and specific gravity tests. The SPT-N values were observed to vary between 4 and 100 and the in-situ bulk density of undisturbed samples as recovered through pitcher sampler are in the range of 13.24 ~ 18.44 kN/m3. The soil samples are classified as poorly graded sand (SP), poorly graded sand with silt (SP-SM) and silty sand (SM) on the basis of Unified Soil Classification System. The values of minimum dry unit weight fall in the range of 12.22~14.95 kN/m3 and maximum dry unit weight varies in the range of 14.64~19.17 kN/m3 as obtained through vibratory table. Based on the test results, correlation analysis was performed to identify the parameters that affect relative density. The parameters include SPT-N value corrected for field procedures (N60), relative density (Dr), void ratio range ( ), effective overburden stresses and in-situ dry density (γdf). Based on the results of correlation analyses, it was observed that SPT-N values alone cannot be related to Dr. Therefore, multiple regression analysis was carried out using Statistical Package for the Social Sciences (SPSS) software and relation between relative density, corrected SPT-N value and effective overburden stress is being proposed. The variation between experimental and predicted values falls within ± 10% at 95% confidence interval. Validation of the proposed correlation was also performed by using an independent data set which indicated that the prediction by using the proposed correlation also falls within ± 10%. Further, comparison of the proposed correlation with other similar relationships already available in the literature was also performed. In addition to the above, correlation between φ and SPT-N60 has also been proposed. It has been observed that the experimental and predicted values of friction angle fall within ± 10% with 95% confidence interval. The proposed correlations may be very useful in the field of geotechnical engineering during feasibility/preliminary design stage for rapid estimation of relative density or friction angle based on the field SPT-N60 values.

휴대용콘의 선단저항값을 이용한 모래의 상대밀도 및 내부마찰각 추정

박재성,손영환,노수각,봉태호,Park, Jae-Sung,Son, Young-Hwan,Noh, Soo-Kack,Bong, Tae-Ho 한국농공학회 2012 한국농공학회논문집 Vol.54 No.4

Sand is one of the essential materials used for social infrastructure construction such as embankment, landfill and backfill. It was known that mechanical properties and shear strength of sand are closely related to relative density. Therefore it is very important to determine accurate relative density. In this study, Portable Cone Penetration Tester (PCPT) was used to estimate the relative density and the internal friction angle of sand. PCPT cone-tip resistance ($q_c$) was measured changing the relative density of the two soil samples.Standard sand (JMJ) and Busan sand (BS). Also, a direct shear test was performed to investigate relationship between relative density and internal friction angle. The size and shape of soil particles were confirmed by using Scanning Electron Microscope (SEM). As a result, the log value of $q_c$ was linearly correlated with relative density and internal friction angle. In particular, the internal friction angle of BS sample was greater than that of JMJ, which was due to difference of the shape and mean size of particles. This result shows that it is important to determine the shape and size of particles as well as relative density to define mechanical property of sand. Through this study, it can be more effectively and conveniently to investigate relative density and shear strength of sand by using PCPT in situ.

함수비를 고려한 모래의 상대밀도 추정을 위한 Fall Cone 관입량의 적용

최우석,손영환,박재성,노수각,봉태호,Choi, Woo-Seok,Son, Young-Hwan,Park, Jae-Sung,Noh, Soo-Kack,Bong, Tae-Ho 한국농공학회 2012 한국농공학회논문집 Vol.54 No.5

Relative density, used to express dynamics condition of sand quantitatively, is measured by RI Test, Standard Penetration Test and Cone Penetration Test. Each measurement method has demerits, which is complicated or needs a specific analysis instrument and an analysis of expert. Also the ground is in wet condition commonly because of an unsaturated zone between a saturated zone and a surface, so the behaviour of the ground has different engineering properties unlike the dry ground and it diminishes accuracy of measuring relative density. In this study, the correlation between relative density and penetration of fall cone test in dry condition and wet condition with variation of water content was analyzed and a simple measuring method for relative density was suggested. As a result, there were difference of penetration between dry sands and wet sands, the correlation between relative density and penetration showed linear expression and relative density could be measured by the linear relation.

Usefulness of Quantitative Analysis Using Relative Electron Density-Based Image of Subsolid Nodule in Chest HRCT

김효서(Hyo-Seo Kim),김성관(Sung-Kwan Kim),조장우(Jang-Woo Jo),서은희(Eun-Hee Seo),대창민(Chang-Min Dae),채희창(Hee-Chang Chae) 대한CT영상기술학회 2023 대한CT영상기술학회지 Vol.25 No.2

흉부 고해상도 CT로 발견되는 반고형결절의 진단에 있어 상대적인 전자밀도 기반 영상을 이용한 정량적 분석의 유용성에 대해 연구하고자 하였다. 팬텀 연구는 흉부 팬텀에 인공 결절들을 위치시키고 CT number(HU)와 상대적인 전자밀도(%EDW) 및 결절의 최대 직경을 측정하였다. 임상 연구는 2022년 04월부터 2023년 01월까지 반고형결절이 있는 172명의 환자를 대상으로 하였다. 두 그룹(부분고형결절, 순수간유리결절)으로 나눈 후 CT number 기반 영상과 상대적인 전자밀도 기반 영상에서 반고형결절의 영역별 용적과 직경을 측정하였다. 관심영역을 설정하여 측정된 CT number(HU)와 상대적인 전자밀도(%EDW)의 상관관계를 연구하였다. 팬텀 연구에서 측정한 CT number(HU)와 직경은 인공 결절 본래의 값들과 유의한 차이를 보이지 않았다.(P>0.05) 임상 연구 결과, 두 그룹 모두 반고형결절의 용적과 직경이 CT number 기반 영상 보다 상대적인 전자밀도 기반 영상에서 증가하는 유의한 차이를 보였다.(P<0.05) 팬텀과 임상 연구에서 측정한 CT number(HU)와 상대적인 전자밀도(%EDW)는 강한 양의 상관관계를 나타냈다.(P<0.05) CT number 기반 영상과 상대적인 전자밀도 기반 영상을 함께 이용하여 시각적인 영상 정보를 제공한다면 반고형결절의 정확한 정량적 분석을 통해 향후 치료 계획을 수립하는데 많은 이점이 될 수 있을 것으로 사료된다. To study the usefulness of quantitative analysis using the relative electron density-based image in the diagnosis of subsolid nodule by chest high-resolution CT. The phantom study measured the CT number(HU), relative electron density(%EDW) and maximum diameter of the nodules by placing artificial nodules in the chest phantom. The patient study was conducted on 172 patients with subsolid nodules from April 2022 to January 2023. The volume and diameter of subsolid nodules in the CT number-based image and relative electron density-based image were measured separately after dividing the two groups: mixed ground-glass nodule and pure ground-glass nodule. The correlation studied between measuring the CT number(HU) and relative electron density(%EDW) by setting the region of interest. The CT number(HU) and diameter values in the phantom study were not significantly different from the actual values of the artificial nodules.(P>0.05) As a result of the patient study, the volume and diameter of subsolid nodules were increased in the relative electron density-based image compared to the CT number-based image for both the mixed ground-glass nodule and pure ground-glass nodule groups.(P<0.05) The CT number(HU) and relative electron density(%EDW) showed a strong positive correlation in both the phantom and patient study.(P<0.05) Providing visual imaging information using CT number-based and relative electron density-based images simultaneously can offer many advantages in establishing future treatment plans through accurate quantitative analysis of subsolid nodules.

Porous Plate를 이용한 개선된 레이닝 시스템

최성근,이문주,추현욱,홍성진,이우진 한국지반공학회 2007 한국지반공학회논문집 Vol.23 No.6

Raining method has been widely used for preparing sand specimen because of its ability to reconstitute the homogeneous specimen with desired relative density and its reliability established by the numerous experiments on diverse influential factors. In conventional raining methods, adjustment of relative density is achieved by controlling the shutter porosity and the whole system is required to be re-adjusted to achieve the target relative density when the granular characteristics are changed. It is also observed from conventional methods that certain degrees of spatial variation in density exist and the limited range of relative density is reproduced. In this paper, raining system with porous plate is proposed. It is shown that the wide range of relative density can be achieved by controlling falling height only. This enhanced system is able to obviate the subtle control of shutter porosity and minimize the effect of falling distance, which in turn ensures the homogeneity of the specimen, especially for low relative density.

통계적 분석에 의한 정상상태조건을 만족하는 교통량-밀도 관계 도출

김영호 대한교통학회 2006 대한교통학회지 Vol.24 No.5

교통류 이론에서 fundamental diagram이라고 불리는 교통량-밀도 관계는 stationary 상태에서의 교통량과 밀도사이의 평형관계 (equilibrium relation)를 나타낸다. 본 연구에서는 개별차량 데이터를 이용하여 교통량-밀도 관계의 전제조건인 stationary 조건을 만족하는 데이터를 추출하는 방법을 제시하였고, stationary 조건을 만족하는 데이터를 교통량-밀도 평면에 도시하였다. 개별차량의 흐름이 자유교통류상태와 혼잡교통류상태에서 상이하며 지점에서 관측된 데이터가 서로 다른 특성의 시계열특성을 보인다는 점에 근거하여 두가지 상태에 따라 서로 다른 stationary 조건을 제시하였다. 본 논문에서 제시된 stationary 조건을 실제로 관측된 데이터에 적용한 결과 자유교통류상태의 stationary 조건을 만족하는 데이터는 현재까지 알려진 바와 같이 교통류-밀도 관계의 왼쪽가지에 위치하고, 혼잡교통류상태의 stationary 조건을 만족하는 데이터는 교통류-밀도관계의 오른쪽 가지에 위치한다. 또한 본 연구에서 제시된 방법론에 따라 교통류-밀도관계의 전범위에 걸쳐 stationary 조건을 만족하는 데이터를 구별하여 교통류-밀도평면에 도시한 결과 교통류의 거의 전영역에 걸쳐 재현가능한 관계가 나타나는 것을 확인할 수 있었다. The flow-density relations represent equilibrium relations between flow and density in the stationary state. Using individual vehicle data this paper proposed a method to filter traffic data in the stationary state and showed flow-density relations produced by the traffic data in the stationary state. The proposed method is based on the idea that free flow and congested flow show totally different traffic behaviors and time series of the traffic data observed at detection stations. The traffic data collected from the stationary state in the free flow using this filtering method consist in the left branch of the flow-density relation and the traffic data collected from the stationary state in the congested flow consist in the right branch of the flow-density relation. The traffic data in the stationary state show reproducible flow-density relation in the almost whole range of the traffic flow.

Development of a Stand Density Management Diagram for Teak Forests in Southern India

Tewari, Vindhya Prasad,Alvarez-Gonz, Juan Gabriel Institute of Forest Science 2014 Journal of Forest Science Vol.30 No.3

Stand Density Diagrams (SDD) are average stand-level models which graphically illustrate the relationship between yield, density and mortality throughout the various stages of forest development. These are useful tools for designing, displaying and evaluating alternative density regimes in even-aged forest ecosystems to achieve a desired future condition. This contribution presents an example of a SDD that has been constructed for teak forests of Karnataka in southern India. The relationship between stand density, dominant height, quadratic mean diameter, relative spacing and stand volume is represented in one graph. The relative spacing index was used to characterize the population density. Two equations were fitted simultaneously to the data collected from 27 sample plots measured annually for three years: one relates quadratic mean diameter with stand density and dominant height while the other relates total stand volume with quadratic mean diameter, stand density and dominant height.

Development of a Stand Density Management Diagram for Teak Forests in Southern India

Vindhya Prasad Tewari,Juan Gabriel Álvarez-Gonz 강원대학교 산림과학연구소 2014 Journal of Forest Science Vol.30 No.3

Stand Density Diagrams (SDD) are average stand-level models which graphically illustrate the relationship between yield, density and mortality throughout the various stages of forest development. These are useful tools for designing, displaying and evaluating alternative density regimes in even-aged forest ecosystems to achieve a desired future condition. This contribution presents an example of a SDD that has been constructed for teak forests of Karnataka in southern India. The relationship between stand density, dominant height, quadratic mean diameter, relative spacing and stand volume is represented in one graph. The relative spacing index was used to characterize the population density. Two equations were fitted simultaneously to the data collected from 27 sample plots measured annually for three years: one relates quadratic mean diameter with stand density and dominant height while the other relates total stand volume with quadratic mean diameter, stand density and dominant height.

모래지반의 상대밀도에 따른 횡방향 반복재하 시 말뚝의 극한지지력 평가

정충기,백성하,김준영,이승환 한국지반공학회 2016 한국지반공학회논문집 Vol.32 No.4

Pile foundations used as offshore support structures are dominantly subjected to cyclic lateral loads due to wind andwaves. In this study, a series of cyclic lateral load tests were performed on a pre-installed aluminum flexible pile insandy soil with three different relative densities (40%, 70% and 90%) in order to evaluate the effect of cyclic lateralloads on lateral load capacity of a pile. The cyclic lateral loads increased the lateral load capacity of a pile at 40%relative density, whereas they decreased it at 70% and 90% relative densities. This can be explained by the fact thatthe cyclic lateral loads slightly densified the surrounding soil in relatively loose sand (40%), while the surrounding soilwas disturbed in relatively dense sand (70% and 90%). These effects were more obvious as the cyclic lateral loadamplitude increased, being independent with the saturation. Also, from the test results, an empirical equation for thelateral load capacity of a cyclic laterally loaded pile in sandy soil was developed in terms of relative density of thesoil and the cyclic lateral load amplitude.

Effect of relative density on the shear behaviour of granulated coal ash

Yoshimoto, Norimasa,Wu, Yang,Hyodo, Masayuki,Nakata, Yukio Techno-Press 2016 Geomechanics & engineering Vol.10 No.2

Granulated coal ash (GCA), a mixture of the by-product from milling processes with a small amount of cement added, has recently come to be used as a new form of geomaterial. The shear strength and deformation behaviours of GCA are greatly determined by its relative density or void ratio. A series of drained triaxial compression tests were performed on cylindrical specimens of GCA at confining pressures of between 50 kPa and 400 kPa at initial relative densities of 50%, 70% and 80%. Experimental results show that a rise in relative density increases the peak shear strength and intensifies the dilation behaviour. The initial tangent modulus and secant modulus of the stress-strain curve increase with increasing initial relative density, whereas the axial and volumetric strains at failure decrease with level of initial relative density. The stress-dilatancy relationships of GCA at different relative densities and confining pressures display similar tendency. The dilatancy behaviour of GCA is modelled by the Nova rule and the material property N in Nova rule of GCA is much larger than that of natural sand.