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Application of the Random Forest Model to Predict the Plasticity State of Vertisols

Al Masmoudi Yassine, Bouslihim Yassine, Doumali Kaoutar, El Aissaoui Abdellah, Namr Khalid Ibno

Journal of Ecological Engineering

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2021

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Vol. 22, nr 2

36--46

EN

Vertisol plasticity is related to moisture content, and it requires an in-depth physicochemical characterization. This information allows us to use the land under the most adequate conditions and avoid soil physical degradation, especially its compaction. The objective of this study was to characterize the Vertisol in the Moroccan region of Doukkala-Abda and to predict soil plasticity based on the physicochemical parameters of soil, such as texture, electrical conductivity, Soil Organic Matter (SOM) and other chemical parameters for 120 samples. Determination of soil plasticity using Atterberg limits is a challenging and time-consuming method. Thus, this study aimed to develop a new model that can predict soil plasticity using the Random Forest algorithm. The soils presented homogeneity in the majority of physicochemical parameters, except a significant difference observed in the SOM and the electrical conductivity, which in turn influenced the soil plasticity state. The results showed significant and positive correlations between SOM, Soil Clay Content (SCC), Electrical Conductivity (EC), and plasticity in the Vertisol fields of the region. For the training phase, the model gave excellent results with a coefficient of determination of 0.995 and an RMSE of 0.164. Almost the same results were observed in the validation phase with a coefficient of determination of 0.974 and an RMSE of 0.361, which shows that the model succeeded in predicting plasticity in both phases. On the basis of these results, this model can be used for the plasticity prediction using other physicochemical parameters and the Random Forest Model. The prediction of soil plasticity is an important parameter to respect the timing of introducing machines/tools in the fields and avoid Vertisol degradation.

2

Estimation of unsaturated hydraulic conductivity function: implication of low to high suction measurements

Saha Abhisekh, Sekharan Sreedeep

Acta Geophysica

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2021

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Vol. 69, no. 2

547--559

EN

Establishment of the relationship between soil suction and water content, commonly termed as soil–water characteristic curve (SWCC), is of prime importance in the feld of unsaturated soil mechanics. There are several instruments available that can be used to measure the SWCC of soil, but every suction measuring device has its own limitations in terms of its suction measurement range. Therefore, the preciseness of the estimated unsaturated soil properties largely depends on the range of suction measurements and the type of instruments used. The primary objective of this study is to quantify the error that can occur during the estimation of unsaturated hydraulic conductivity function (UHCF) from SWCC for low plastic soils. Experiments were performed to investigate the infuence of diferent suction measurement devices on the estimated UHCF for four diferent soils with varying clay content. A dew point potentiometer (WP4) and a miniature tensiometer (T5) have been used in this study for the suction measurement. The SWCC of the selected soils were predicted mathematically using a commonly used pedo-transfer function (PTF). The experimental results clearly indicated that the sole use of WP4 overestimated the SWCC parameters, as well as UHCF (overestimation in the conductivity value is in order of 104 times). Rather, a combination of T5 and WP4 data, within their accurate range, provides a more precise estimation of UHCF. Further, the accuracy of the PTF was found very efective for low plastic soils with a relatively low percentage of clay (% clay < 10), in the absence of any experimental data.

3

The analysis of stresses and displacements beneath strip foundations in terms of FEM

Sternik K.

Foundations of Civil and Environmental Engineering

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2010

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No. 13

73--89

EN

Soil is a material dependent on the load history. The load history has a significant influence on stress distribution in the ground beneath the footing and the settlement of a foundation. In the paper the load history has been considered as the sequence of loading the ground with two strip footings. Differences in the distributions of stresses in the ground as well as the settlements of footings have been shown. Nonlinear load-settlement relationship does not allow the application of the principle of superposition.