Evaluation of relative density and friction angle based on SPT-N values

Abstract

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 (D r ), 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/m 3 . 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/m 3 and maximum dry unit weight varies in the range of 14.64~19.17 kN/m 3 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 (N 6 0 ), relative density (D r ), void ratio range ( ), effective overburden stresses and in-situ dry density (γ d f). Based on the results of correlation analyses, it was observed that SPT-N values alone cannot be related to D r . 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-N 6 0 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-N 6 0 values.

Geotechnical Property Modeling and Construction Safety Zoning Based on GIS and BIM Integration

“…The authors used SPT-N information, because of the ease of correlation of SPT-N with other geotechnical properties. The proposed method is applied in the Peshawar region, Pakistan where ground response studies such as shear wave velocity profiles are typically calculated using SPT-Vs correlations [8,63]. On the other hand, the study uses geotechnical information which has been collected from the local consultants.…”

“…The advantage of using SPT-N information is the simplicity and utilization of its empirical correlation. It can be used to calculate the other geotechnical parameters of soil such as the angle of internal friction, relative density, shear modulus, shear wave velocity, Poisson's ratio, and shear strength [7][8][9]. The geotechnical modeling of the construction site can ensure the safe execution of the project and enhancing its feasibility, planning, and design phase [10,11].…”

Thematic Maps for the Variation of Bearing Capacity of Soil Using SPTs and MATLAB

“…All these conditions should be evaluated by the geotechnical engineer [1,5]. There are several studies correlating the corrected SPT values and different geotechnical properties of soil such density, undrained shear strength, shear wave velocity, and liquefaction potential, but the results of these correlations are still considered preliminary and cannot be used for detailed design of foundations [6][7][8][9][10][11][12][13]. Additionally, the correlation between the results of SPTs with some promising field techniques such as pressuremeter test (PMT) and cone penetration test (CPT) using statistical analysis have been presented, which gives support for the results of SPT by newly developed techniques [14][15][16].…”

“…The SPTs were conducted in 135 boreholes (BHs) extended to a depth of 10 m from the existing ground level and distributed over all the plane areas of Al-Basrah city. The soil of this city varies from soft clay to silty clay and sometimes become silty sand, and the results of the study provide a simple and easy tool for calculating the bearing capacity of shallow foundation in Al-Basrah city, which can be used for preliminary design without conducting tests in the field or laboratory [13,[17][18][19][20].…”

Estudio experimental y numérico del comportamiento de excavaciones ejecutadas mediante la técnica de suelo claveteado (soil nailing) en suelos de la ciudad de Quito (Ecuador).

“…El ensayo "in situ" más usado y económico es el de penetración estándar (Standard Penetration Test o SPT), el cual mide la resistencia del suelo a la penetración a determinada profundidad. También puede ser usado para estimar las propiedades de suelos granulares (Mujtaba et al, 2017), correlacionar la resistencia al corte no drenada de suelos cohesivos, calcular la capacidad del suelo de soporte y estimar los asentamientos.…”