scholarly journals Estimation of Pressuremeter Modulus and Limit Pressure in Weathered Granite Based on the SPT-N Value and Chemical Weathering Index: A Case Study in South Korea

2021 ◽  
Vol 11 (8) ◽  
pp. 3411
Author(s):  
Seung-Hwan Lee ◽  
Tae-Young Kwak ◽  
Ka-Hyun Park
Keyword(s):  
South Korea ◽  
Chemical Weathering ◽  
Regression Analyses ◽  
Weathering Index ◽  
N Value ◽  
Weathered Granite ◽  
Limit Pressure ◽  
Simple Regression ◽  
Pressuremeter Modulus ◽  
Spt N Value

A pressuremeter test (PMT) is a representative and highly reliable in situ test for assessing the stress–strain behavior of weathered granite. Its application, however, is restricted by its cost and time requirements. Many researchers have also investigated the correlations between the SPT-N value and the pressuremeter modulus (Em) and limit pressure (PL) of soils, but they have mostly focused on sand, silt, and clay and have employed simple regression analysis. In this study, equations for Em and PL were derived for weathered granite through multiple nonlinear regression analyses using a chemical weathering index that quantitatively represents the degree of weathering. Nonlinear multiple regression analyses were conducted by combining the allometric models that produced the optimal correlations between Em, PL, energy corrected SPT-N (SPT-N60), and normalized VR (Vogt’ ratio) with vertical effective stress. The obtained equations for Em and PL had higher R2 values (0.76 and 0.46, respectively) compared with the simple regression equations reported in previous studies. Because local characteristics are important determinants of the engineering properties of geo-materials, the Em and PL equations proposed in this paper are intended for use in geotechnical surveys of weathered granite in South Korea.

scholarly journals Relationship between Chemical Weathering Indices and Shear Strength of Highly and Completely Weathered Granite in South Korea

2021 ◽  
Vol 11 (3) ◽  
pp. 911
Author(s):  
Seung-Hwan Lee ◽  
Choong-Ki Chung ◽  
Young-Woo Song ◽  
Sang-Inn Woo
Keyword(s):  
Shear Strength ◽  
South Korea ◽  
Chemical Weathering ◽  
Friction Angle ◽  
Standard Penetration Test ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Weathered Granite ◽  
Weathering Indices ◽  
Chemical Index Of Alteration

In South Korea, weathered granite is widely distributed and has been used as a bearing stratum for various structures. Therefore, it is important to determine the shear strength of the weathered granite. However, it is difficult to obtain reliable shear strength parameters with laboratory tests or standard penetration test (SPT) because weathered granite is easily crushed during the sampling process, and the penetrability of SPT is not secured. On the other hand, it is well known that weathering affects the variation of geotechnical properties. Based on this concept, this study reports a correlation between the shear strength parameters and the chemical weathering indices of the weathered granite. In this study, the pressuremeter test (PMT) was adopted to determine the friction angle of the weathered granite. For the identical granite, the chemical weathering indices (Vogt’s Ratio (VR), Chemical Index of Alteration (CIA), and Mobiles Index (Imob)) were measured by X-ray fluorescence (XRF). An estimating model considering both site-specific characteristics and degree of weathering was used, and the CIA showed the best correlation (R2 = 0.66) with friction angle among the weathering indices. Since the ratio of measured friction angle over the predicted one was distributed in the range from 0.8 to 1.2, it is more reasonable to predict friction angles based on CIA comparing to using the SPT-N value. It can contribute to a better estimation of friction angles of weathered granite.

scholarly journals Provenance and weathering index of the Upper Cretaceous São Carlos Formation and its tectonic significance in the eastern Bauru Basin, SE Brazil

2019 ◽  
Vol 19 (3) ◽  
pp. 77-94
Author(s):  
Lara Ferreira Neves ◽  
Alessandro Batezelli
Keyword(s):  
Trace Elements ◽  
Chemical Weathering ◽  
Upper Cretaceous ◽  
Source Area ◽  
Sedimentary Basins ◽  
Major And Trace Elements ◽  
Published Data ◽  
Weathering Index ◽  
Se Brazil ◽  
Eastern Border

Geochemistry of major and trace elements has been used as an important tool for the study of provenance and tectonic and climatic evolution of sedimentary basins. The São Carlos Formation is an Upper Cretaceous unit that lies on the eastern border of the Bauru Basin. Despite the paleontological and paleodepositional studies performed in this unit in the last years, little is known about the correspondence between tectonic and climatic conditions acting during the first stages of sedimentation. The hypothesis of this paper is to evaluate São Carlos and Araçatuba formations and understand the evolution of the eastern border of the basin. Thus, were conducted geochemical studies using X-ray fluorescence on sandstones, siltstones, and shales from the São Carlos Formation. According to the chemical weathering index, which presented values ranging from 57.12 to 71.58%, the oxides of major elements indicate that moderate weathering processes affected the source area, possibly associated with the arid-semiarid climate. Alkaline rocks, granites, gneisses, and metasediments were the main lithotypes of the source area. Ternary diagrams show that the tectonic environment was equivalent to the passive continental margin, coinciding with the Serra do Mar and, secondarily, Alto Paranaíba Uplift regions. Based on major and trace elements, their ratios, and published data on the basin, was elaborated a paleogeographic model of the eastern border of the Bauru Basin, concluding that the source area of the sediments was constituted by intermediate and felsic rocks, sometimes recycled by sedimentary processes.

scholarly journals Estimating SPT-N Value Based on Soil Resistivity using Hybrid ANN-PSO Algorithm

2018 ◽  
Vol 995 ◽  
pp. 012035
Author(s):  
Mohd Nur Asmawisham Alel ◽  
Mark Ruben Anak Upom ◽  
Rini Asnida Abdullah ◽  
Mohd Hazreek Zainal Abidin
Keyword(s):  
Pso Algorithm ◽  
Soil Resistivity ◽  
N Value ◽  
Spt N Value

Regression model for evaluating liquefaction potential by discriminant analysis of the SPT N value

2005 ◽  
Vol 42 (3) ◽  
pp. 856-875 ◽  
Author(s):  
Sheng-Yao Lai ◽  
Ping-Sien Lin ◽  
Ming-Jyh Hsieh ◽  
Hoi-Fung Jim
Keyword(s):  
Discriminant Analysis ◽  
Standard Penetration Test ◽  
Cyclic Stress ◽  
Soil Liquefaction ◽  
Liquefaction Resistance ◽  
Multivariate Statistical ◽  
Liquefaction Potential ◽  
Cyclic Stress Ratio ◽  
N Value ◽  
Spt N Value

Discriminant models are developed for evaluating soil liquefaction potential, using standard penetration test (SPT) data for 592 occurrences of liquefaction and nonliquefaction. The discriminant model used is a multivariate statistical method. The square root of the SPT N value, (N1)601/2, and the logarithm of the cyclic stress ratio, ln CSR7.5, are adopted as the major parameters for analyses. Two models measuring liquefaction resistance through the SPT N value are also established in this study, which allows calculated results to be compared with the empirical curves. Key words: liquefaction, discriminant analysis, misclassified probability.

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