Abstract:ASTM Test Method for Classification of Soils for Engineering Purposes (D 2487) was significantly revised in 1983. The revisions require that soil is to be classified by using both a symbol and a name, and the group names were standardized. Organic silts and clays were redefined to recognize that organic soils occur that plot above the “A” line on the plasticity chart. More precise guidelines were established, particularly with regard to plasticity, so that only one particular classification will result. If boa… Show more
“…2(a)]. • Organic soils may be found above or below the A-line (Howard 1984). • The classification of mixtures made of plastic and nonplastic grains may be determined by the weight of the coarse nonplastic fraction, whereas the sediment hydraulic and mechanical properties remain controlled by the high-plasticity fines (further details are discussed subsequently).…”
The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil "electrical sensitivity." Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems.
“…2(a)]. • Organic soils may be found above or below the A-line (Howard 1984). • The classification of mixtures made of plastic and nonplastic grains may be determined by the weight of the coarse nonplastic fraction, whereas the sediment hydraulic and mechanical properties remain controlled by the high-plasticity fines (further details are discussed subsequently).…”
The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil "electrical sensitivity." Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems.
“…The gradation parameters of the soil, namely, the uniformity coefficient (Cu) and the coefficient of curvature (Cc), are tabulated and reported in Table 2 . For both samples, the fraction of fines is less than 5%, the uniformity coefficient (Cu) > 6, and the coefficient of curvature lies between 1 < (Cc) < 3, classifying both debris samples as SW, i.e., well-graded sands, gravelly sands, with little or no fines ( Selig and Howard, 1984 ). Figure 4 Particle-size distribution curve of the debris materials.…”
Slope stability assessment is essential for safe and sustainable development widely applied in mining, civil, and environmental engineering projects around the world. This study aimed to conduct a stability analysis of a selected Himalayan road cut slope from two different sections, named sections (A) and (B). The strength reduction factor (SRF) based on the finite element method was used to simulate the slope sections using Phase2 software. A mesh pattern of six node triangle elements was used during the numerical simulation. The Mohr-Coulomb parameters and other inputs used in the numerical modelling of the investigated slope were estimated by different geotechnical tests, namely, the direct shear test, density analysis test, rock hardness test, and Brazilian test. The results indicated that the critical SRF of the completely weathered slope profile section (A), with a relatively low overall angle, was found to be 1.25, which is approximately 50% lower than the value obtained in the moderately to highly weathered profile section (B), equal to 2.53. These results are in agreement with other published studies, which revealed that the geometry of a slope influences the weathering grade, which in turn destabilizes the slope. The results of this study will help in engineering slope design considering the influence of weathering.
“…Prior to preparing these slurry samples for consolidation testing, we conducted preliminary investigations. According to the Unified Soil Classification System ASTM D2487 (Howard 1984), the dredged soil samples were categorized as Low Plastic Clay (CL). We determined the specific gravity (GS) following ASTM D854 (ASTM 2016) and assessed the Atterberg limits in accordance with the ASTM D4318 (ASTM 2018) standard.…”
This study delves into the consolidation behavior of Louisiana marsh soil, employing a one-dimensional nonlinear approach and leveraging data from ongoing wetland restoration projects and a series of laboratory experiments. A precise model is developed to accurately predict slurry/marsh consolidation, guided by tactful interpretations of oedometer test results and incorporating specific parameters tailored for large strain consolidation. The research draws on Gibson's nonlinear consolidation theory, implemented in MATLAB, which accounts for essential factors such as the finite strain coefficient of consolidation (𝑔), variable compressibility coefficients (λ), and other soil properties. The study reaffirms the model's robustness through validation against laboratory and field data. The findings, encompassing settlement-time curves, degree of consolidation-time profiles, and void ratio fluctuations along with depth, provide indispensable tools for field engineers in estimating allowable loads, predicting settlement, and designing coastal restoration projects. This contribution enhanced the understanding of self-weight consolidation in geotechnical engineering practices. This research has significant implications for advancing coastal restoration strategies and the sustainable management of wetlands.
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