Forecasting the Compressibility Parameters of Gypseous Soil using Artificial Neural Networks

To ensure safe design of structures against settlement, it is necessary to determine the compressibility parameters of the underneath soil especially compression and rebound indices. In this paper, an approach to forecast the compressibility parameters of gypseous soils based on index parameters was developed using Artificial Neural Networks technique. Two equations were developed to estimate compression and rebound indices using back propagation algorithm to train multi-layer perceptron, in which good agreements were achieved. The input parameters used were: the depth, gypsum content, liquid limit, plastic limit, plasticity index, passing sieve No.200, dry unit weight, water content and initial void ratio. Two output parameters were determined including compression index and rebound index. A parametric study was also conducted to investigate the generalization and robustness of both models. The findings indicate that both models were reliable within the range of utilized data. It was found that gypsum content has the highest effect on the compressibility index followed by water content, plasticity index, dry unit weight and plastic limit, while other parameters have lower effect. The gypsum content has the highest effect again on the rebound index followed by passing sieve No.200, initial void ratio, plastic limit and plasticity index, while other parameters have lower effect.

Geotechnical Properties of Soft Marine Soil at Chan May Port, Vietnam

Soft marine soil deposit is distributed under the sea with many special properties. This type ofsoil is rarely researched in Vietnam because of the difficult geotechnical investigation under the sea level.In this paper, the experimental laboratories were performed to investigate the geotechnical properties ofsoft marine soil at Chan May port, Vietnam. The field investigation results indicate that the thickness ofsoft soil varies from a few meters to more than ten meters. Soft soil has a high value of water content,void ratio, and compressibility and a low value of shear strength. The compression index has a goodrelationship with water content, liquid limit, and dry unit weight. The unit weight, shear strength, and preconsolidationpressure increase with the increase of depth. These results show that the soil in the studyarea is unfavorable for construction activities.

Experimental Study of Bearing Capacity Effect in Swelling Soil

The current study aims to investigate the effects of swell pressure on the bearing capacity of swelling soil. A model and some laboratory tests have been created to investigate the swell pressure effect on the bearing capacity variation of soil swelling due to swelling pressure. The influence of varying water content w/c and dry unit weight (γ d ) on the shear strength and swelling pressure was studied. The soil has been taken from Diwan Residential Compound-Mosul. It is classified as highly swelling soil. The swell pressure of soils at their natural water content reached 385 kN / m2 . Experiment results show that the parameters of shear resistance decreased with the w/c increase at the constant value of (γ d ), increased with the (γd ) increase when the w/c was constant. Results show that the swelling pressure decreased with the w/c increase, while it increased with the (γ d ) increase. Also, the results obtained using was model show that the resistance of bearing capacity of pre-saturated selected soil was 196 kN / m 2, while the bearing capacity was 620kN / m 2 when taking into account in the generation of swelling pressure.

Prediction of undrained shear strength and correlation in between soil parameters

Correlation of soil parameters has undeniable benefit in the determination of engineering properties of soil to solve problems in geotechnical Engineering area. The tests were conducted within geotechnical laboratory. These tested soil parameters, used in the correlation analysis are unconfined compressive strength, bulk unit weight and dry unit weight. The aim of this study is proposing a relationship in between the strength parameter with some of the index properties of soils using statistical regression analysis. The linear regression analyses have been done for prediction of unconfined compressive strength (qu ) from bulk and dry unit weight as model-1 and model-2 respectively. And dry unit weight was predicted from bulk unit weight as model-3. Model-4 represents the multiple linear regression analysis to predict qu . The health of developed models is measured by coefficient of determination (R 2) values. Though, model-1, model-2, model-3 and model-4 have R – squared values of 0.9112, 0.9333, 0.9109 and 0.9452 respectively. Therefore, they are correlated strongly and positively. The prediction of unconfined compressive strength of these soils correlated in linear regression, are fairly determined with Model-2 compared with model-1 and model-4 (MLR).

Relationship Between Compressive Strength and Splitting Tensile Strength of Palm Kernel Shell Concrete

The use of palm kernel shell (PKS) has gained acceptance in the production of concrete. Compressive strength is the mostly used strength characteristics of concrete. The compressive strength CS of concrete should provide a good basis for predicting the splitting tensile strength STS. The aim of this study is to establish a mathematical relationship between the CS and STS of concrete produced with PKS. In this study, coarse aggregates was fully replaced with PKS at varying water-cement ratios (w/c) for concrete mix ratios 1:1½:3 and 1:2:4. Unit weigth of the PKS, slump, compressive and splitting tesnsile strength were determined. A relationship between CS and STS was developed for the different w/c ratios using exponential function aproximation. Physical property tests carried out on the PKS characterized it as lightweight aggregate with saturated surface dry unit weight of 1.27. The slump revealed that PKS concrete at 0.3 and 0.4 w/c is stiff and not workable. CS and STS at 28day for mix ratio of 1:1½:3 at w/c of 0.3, 0.4, 0.5 and 0.6 were respectively 3.2 and 1.2; 9.4 and 2.1; 10.8 and 2.6; 9.0 and 2.4 N/mm2. The corresponding values obtained for mix ratio 1:2:4 were 3.0 and 1.0, 1.7 and 1.3, 4.5 and 1.6, 7.7 and 1.9N/mm2, respectively. Equations relating CS and STS at 0.3, 0.4, 0.5 and 0.6 w/c were established. It was concluded that PKS concrete produced with mix ratios 1:1½:3 and 1:2:4 performed better in compression and splitting tensile strength at w/c of 0.5 and 0.6.

Empirical Models to Predict Compaction Parameters for Soils in the State of Ceará, Northeastern Brazil

This work developed prediction models for maximum dry unit weight (γd,max) and optimum moisture content (OMC) for compacted soils in Ceará, Brazil, ba M Winnie the Pooh sed on index and physical properties. The methodology included data from soils used in the construction of 15 dams in Ceará, with available information regarding laboratory tests of interest. Correlations were developed using non-linear regression, from 169 laboratory results (83 for training and 86 for validating the models), which presented a R2 of 0,763 for MoPesm (prediction model for γd,max) and 0,761 for MoTuo (model for OMC). A posteriori, the same physical indexes used to train and validate MoPesm and MoTuo were used as inputs of other prediction models available in the literature, whose outputs differed considerably from laboratory results for the evaluated soils. MoPesm and MoTuo were able to satisfactorily predict compaction parameters, with outputs close to those obtained in the laboratory for tested soil samples. Their performance justifies their use for predicting compaction parameters in geotechnical structures that use compacted soils when there are financial restraints, short timeframes, or unavailability of test equipment, particularly in early design stages and preliminary studies, before appropriate soil sampling and field investigation can be conducted, thus saving substantial time and financial resources.

Effect of Fly Ash on Compaction Behavior of Alluvial Soil

Low plasticity, high bearing capacity, low settlement, etc. are the preferred properties for most engineering projects. Alluvial soils are problematic soils because of low bearing capacity, high organic matter content, and high void ratio so they do not meet the preferred condition for engineering projects. It has been necessary to improve unsuitable materials to make them acceptable for construction. Fly ash (FA) has earlier been used for stabilizing roads due to its high content of calcium and silicate oxides which give puzzolanic properties and thus high compression strength. In this research, fundamental engineering properties, compaction behaviors of three types of (fine, medium, and coarse) alluvial deposits, and the effect of fly ash on compaction behavior of these alluvial soils are presented. Alluvial soil is taken from Çiğli, Balatçık (Izmir, Turkey). To determine geotechnical index properties; wet sieve analysis, plastic limit, liquid limit, specific gravity, standard compaction tests were conducted. In order to determine the effect of fly ash on compaction behavior of alluvial deposits, three different samples (fine < 0.425mm, medium < 2mm, and coarse < 4.75 mm) are prepared and 10%, 15%, 20% fly ash by dry weight of soil is mixed and standard proctor test is performed. As a result of laboratory tests, the liquid limit, plastic limit, and plasticity index values obtained as 38.3%, 25.7%, and 12.6%, respectively. The specific gravities for fine, medium, and coarse samples are 2.68, 2.67, and 2.66, respectively. According to the results of wet sieve analysis and consistency limit tests, it was stated that the soil contains large amounts of sand and clay. The washed sieve analysis and consistency limit tests results were evaluated according to USCS. The conducted test results have shown that maximum dry unit weight for fine, medium, and coarse soils are 16.9, 19.35, and 19.55 (kN/m3), and optimum moisture content for fine, medium, and coarse samples are 17, 11, 10.5% respectively. Generally, by increasing the content of FA, maximum dry unit weight decreased and optimum moisture content increased for all three types of alluvial soil. By increasing FA to 20%, maximum dry unit weight of medium and coarse soils decreases 1.5% and 2%, respectively.

Estimation of Optimum Moisture Content and Maximum Dry Unit Weight of Fine-Grained Soils using Numerical Methods

Soil compaction is one of the basic engineering techniques, which is carried out to guarantee the stability of soils dependent on specified strength. Nonetheless, in large-scale construction projects, the estimation of compaction features required tremendous effort and time that can be saved utilizing empirical relationships at the initial phases. It becomes critical to develop models to predict the compaction features, namely the maximum dry unit weight (γdmax) and optimum water content (WOP). This article attempts to develop models to predict the γdmax and WOP of fine-grained clay soils. Geotechnical tests such as grain size distribution, Atterberg limits, specific gravity, and proctor compaction tests are performed to assess soil samples' physical and hyro-mechanical characteristics. Multivariate analysis is conducted using MINITAB 18 software to develop the predictive models. The validation process of developed models includes the determination coefficient, probability value (p-value), comparison of the predicted values with experimental values, comparison of the models proposed in this study with other existing models found in the recent literature, and employing a different soil data set. The predicted values obtained from the models proposed in this research project are more accurate than other models developed recently. The proposed models estimate the compaction features of fine-grained clay soils with acceptable precision. HIGHLIGHTS Soil compaction is one of the basic engineering techniques perform to guarantee the stability of soils dependent on specified strength In large-scale construction projects, the estimation of compaction parameters required tremendous effort and time that can be saved utilizing empirical relationships at the initial phases This study has developed semi-empirical models to predict the compaction parameters (maximum dry unit weight and optimum water content) of fine-grained soils GRAPHICAL ABSTRACT

Study on effect of laboratory roller compaction on unconfined compressive strength of lime treated soils

Expansive soils are problematic due to their swell—shrinkage behavior and low compressive strength. They are modified generally with additives such as lime, fly ash, and various other inorganic and organic materials. Chemical stabilization treatments can improve expansive soil properties for its reuse in geotechnical applications. The present study investigates the properties of two types of subgrade soil treated with Lime and compacted by three different methods in the laboratory. The study is mainly focused to bring out the effect of different methods of compaction on the unconfined compressive strength of Lime treated soils and untreated soils. Laboratory investigation included pH, Atterberg limits, cation exchange capacity (CEC), compaction, unconfined compression strength (UCS), California Bearing Ratio (CBR), Scanning Electron Micrographs (SEM) and EDAX before and after lime treatment. Tests were performed on lime treated soils (2, 4, 6 and 8% of lime). The soil samples for unconfined compressive strength test were prepared by static, dynamic and roller compaction methods in the laboratory. Roller compaction was performed using indigenously fabricated Roller compactor cum Rutting Analyzer (RCRA). The results indicate that dry unit weight and UCS of roller compacted lime treated soil is lower than that of dynamic compacted soil. However, dry unit weight and UCS of lime treated roller compacted soil are closer to that of statically compacted soil. Cation exchange capacity of both soils before and after treatment with lime were examined, CEC reduced with increase in lime content.