Swelling Pressure Of Soil Research Articles

The effect of initial water content on the swelling pressure of soils

Swelling soils cause serious damage to engineering structures, and they pose a problem worldwide. The fluctuation of water content is one of the most important factors that cause the swelling pressure of soils, especially for soils in arid and semi-arid regions. The swelling soils in these regions are exposed to cycles of volume increase and decrease in the rainy and dry periods. Thus, low-rise buildings and infrastructure constructed on or in these soils are exposed to potential damage. Although the relationship between swelling parameters and the physical-index properties of soils have been investigated in detail in previous research, the effect of variations in the initial water content on the swelling pressure of soils has not yet been sufficiently studied. For this reason, samples were prepared at the same dry unit weight and with different initial water contents to examine the effect of water content on the swelling behaviour of soils. According to swelling test results reported here, there is a statistically significant linear relationship between initial water content and swelling pressure. Some predictive empirical models with high correlation coefficients are obtained. In addition, a new approach called swelling pressure designation (SPD) is recommended for prediction of the swelling pressure of soils of any water content.

Experimental Evaluation of Swelling Pressure in an Unsaturated Kaolin by Direct and Indirect Methods

Various methods have been reported in the literature to measure the swelling pressure of clayey soils. These methods generally include experimental measurements of the swelling pressure of the soil using indirect methods by conventional oedometer apparatus; while the measurement of swelling pressure of compacted samples using direct method has been less considered. Direct methods involve constant volume swell method with initial vertical stress and without applying vertical stress. Indirect methods consist of swell-consolidation (Free-swell and Restricted-swell) and zero swell experiments. In the present study, in addition to using conventional oedometer, an experimental technique using a modified loading frame was employed to directly measure the swelling pressure. It is observed that the swelling pressure measured by direct method is greatly affected by the vertical stress at which the sample is inundated. The measured swelling pressures obtained from direct and indirect methods are compared with each other. The results indicate that zero swell method slightly overestimates swelling pressure compared to the direct method of constant volume swell without initial vertical stress. Furthermore, the methods of free swell-consolidation and restricted swell-consolidation excessively overestimate the swelling pressure. Regarding the actual conditions of the soil in practical works, it seems that the swelling pressure measured by the method of constant volume swell with initial vertical stress is closer to the true value. The effects of initial conditions such as dry unit weight and initial water content on the swelling pressure are also evaluated in all methods.

Swelling Pressure of Soil using a Predictive Tool

The characteristic of expansiveness represented by swelling pressure is considered as major parameter in design of engineering structures. In order to determine the potential expansion, the swelling pressure experiments are usually conducted. In the present study, neuronets have been used to predict swelling pressure of undisturbed as well as remolded soils from given geotechnical parameters such as grain-size distribution, consistency limits, activity, and deferential free swell. Neuronet models relating the potential expansiveness to some geotechnical properties are derived in order to overcome the need to perform lengthy swelling pressure determination experiments. While the remolded soil neuronets (Testing sets) developed in this study might be considered as specific, the remolded soil neuronets (Training sets) can be used to predict swelling characteristics for most soils in India or elsewhere in the world. Similarly the combined datasets used in training & testing may significantly assist earthwork engineers in designing the sub grades and control the detrimental effect caused by volume changes associated with swelling of soil for roads, canals, buildings etc. Moreover, a neural network used in the prediction of expansion may assist the designers in selection of the appropriate water content to compact clays.

Investigation of three methods for evaluating swelling pressure of soils

Abstract Determination of the swelling pressure of six types of clayey soils obtained from northern Jordan were measured using three methods, the Free Swell method, Different Pressure method, and the Zero Swell method. These methods show different values in swelling pressure of the soil. For all six soils, the Free Swell method provided the highest value, whereas the Different Pressure method provided the lowest. Discrepancy in the value of swelling pressure among the methods increases with lower initial water content, higher plasticity index, and clay content. This paper compares the three different methods for evaluating soil swelling pressure and presents mathematical models to predict the soil swelling pressure for each method.