A comparison between the Casagrande cup method and the Fall cone penetrometer devices for determining the liquid limit(LL)was conducted on lateritic soils developed on basalt,granite,and gneiss in the northeast area o...A comparison between the Casagrande cup method and the Fall cone penetrometer devices for determining the liquid limit(LL)was conducted on lateritic soils developed on basalt,granite,and gneiss in the northeast area of Dschang city.The goal was to identify which device provides more reliable results.A total of 133 soil samples were collected and tested using both methods.Additionally,nine representative samples from each parent rock type underwent geotechnical analysis.The granulometric analysis combined with the Atterberg limits enabled soil classification for each substrate.Soils on basalt and gneiss are classified as high plasticity clays,while those on granite are low plasticity clays.Data were analyzed using Microsoft Excel and SPSS version 26.The findings indicated that the Fall cone device produced more accurate results than the Casagrande apparatus,although the difference was not statistically significant.A correlation analysis showed a strong positive relationship between the two methods for soils on basalt,expressed as:LLc=0.78 LLp+16.50,with an R²of 0.60.The correlation was moderate(R^(2)=0.4)for soils on granite and weak(R²=0.1)for soils on gneiss.This relationship should not be generalized to specific soil types,as it is affected by soil plasticity and device configuration.展开更多
Preconsolidation stress （ σP） is the maximum effective stress that a soil has suffered throughout its life. From a geotech- nical point of view, pre-consolidation stress has great importance because it separates el...Preconsolidation stress （ σP） is the maximum effective stress that a soil has suffered throughout its life. From a geotech- nical point of view, pre-consolidation stress has great importance because it separates elastic and reversible deformations from inelastic and only partially irreversible deformations and marks the starting point of high compressibility. In this study we calculated the preconsolidation stress for 72 undisturbed soil samples from the Yellow River Delta, using the oedometer test and applying the method proposed by Casagrande. The results showed that the over-consolidation ratio （OCR-the ratio of pre-consolidation stress to current natural overburden stress） values of the soil from soil surface to 6m depth varied from 1.72 to 15.34 and the maximum pre- consolidation stress was above 200 kPa. In consequence, the soils of the Yellow River Delta are highly over-consolidated within the upper 6m, the OCR decreasing gradually with depth from 6 to 12m. For samples from deeper than 12m the soils were found to be under-consolidated, which was proved by standard penetration tests （SPTs）. The main causes of this type of consolidation are the mineral composition and the designability of the soil body.展开更多
文摘A comparison between the Casagrande cup method and the Fall cone penetrometer devices for determining the liquid limit(LL)was conducted on lateritic soils developed on basalt,granite,and gneiss in the northeast area of Dschang city.The goal was to identify which device provides more reliable results.A total of 133 soil samples were collected and tested using both methods.Additionally,nine representative samples from each parent rock type underwent geotechnical analysis.The granulometric analysis combined with the Atterberg limits enabled soil classification for each substrate.Soils on basalt and gneiss are classified as high plasticity clays,while those on granite are low plasticity clays.Data were analyzed using Microsoft Excel and SPSS version 26.The findings indicated that the Fall cone device produced more accurate results than the Casagrande apparatus,although the difference was not statistically significant.A correlation analysis showed a strong positive relationship between the two methods for soils on basalt,expressed as:LLc=0.78 LLp+16.50,with an R²of 0.60.The correlation was moderate(R^(2)=0.4)for soils on granite and weak(R²=0.1)for soils on gneiss.This relationship should not be generalized to specific soil types,as it is affected by soil plasticity and device configuration.
基金supported by the National Natural Science Foundation of China (Nos. 40472137 and 40606020)
文摘Preconsolidation stress （ σP） is the maximum effective stress that a soil has suffered throughout its life. From a geotech- nical point of view, pre-consolidation stress has great importance because it separates elastic and reversible deformations from inelastic and only partially irreversible deformations and marks the starting point of high compressibility. In this study we calculated the preconsolidation stress for 72 undisturbed soil samples from the Yellow River Delta, using the oedometer test and applying the method proposed by Casagrande. The results showed that the over-consolidation ratio （OCR-the ratio of pre-consolidation stress to current natural overburden stress） values of the soil from soil surface to 6m depth varied from 1.72 to 15.34 and the maximum pre- consolidation stress was above 200 kPa. In consequence, the soils of the Yellow River Delta are highly over-consolidated within the upper 6m, the OCR decreasing gradually with depth from 6 to 12m. For samples from deeper than 12m the soils were found to be under-consolidated, which was proved by standard penetration tests （SPTs）. The main causes of this type of consolidation are the mineral composition and the designability of the soil body.
