https://hal-enpc.archives-ouvertes.fr/hal-00629665/document

Desiccation and cracking behaviour of clay layer from slurry state under wetting-drying cycles

The efficiency of typical chemical and mechanical soil stabilization techniques in mitigating the swelling problem of an expansive soil is investigated through a comprehensive experimental study. Chemical stabilization was generated by traditional agents consisting of lime and cement, and by a commercially branded polymer (CBR PLUS). Mechanical stabilization was applied by means of fiber-reinforcement and swell–shrink cycles. Chemically-treated and fiber-reinforced soil samples were tested for swelling potential in a conventional oedometer apparatus; while swell–shrink cycles were applied using a modified temperature-controlled oedometer. Swell–shrink cycles were applied under room temperature for wetting cycles while the drying process was conducted under a constant temperature of 40 ± 5 °C, and swelling and shrinkage potential were recorded during successive cycles to a point in which swell–shrink equilibrium was attained. Typical strength tests were also conducted for each stabilization scenario which led to maximum reduction in swelling potential. In addition to the experimental program, the swell–time relationship for various stabilization scenarios was simulated using a two-parameter rectangular hyperbola function (2P-RH). Results indicated that all of the proposed stabilization scenarios can guarantee a significant reduction in swelling potential. In the case of lime and cement, reduction in swelling potential was observed to be a function of agent percentage and curing time; whereas for polymer-treated samples the effect of curing was found to be insignificant. Regarding fiber-reinforced samples, reduction in swelling potential was a function of fiber percentage, aspect ratio and fiber tensile strength. Overall, traditional agents proved to be more effective compared to non-traditional techniques. The proposed non-traditional methods, however, displayed promising results posing as great alternatives to lime and cement.

Swelling Potential of a Stabilized Expansive Soil: A Comparative Experimental Study

Long-term Non-linear creep and swelling behavior of Hong Kong marine deposits in oedometer condition

Leakage of oil and its derivatives into the soil can change the engineering behavior of soil as well as cause environmental disasters Also, recovering the contaminated sites into their natural condition and making contaminated materials as both environmentally and geotechnically suitable construction materials need the employment of remediation techniques Bioremediation, as an efficient, low cost and environmental-friendly approach, was used in the case of highly plastic clayey soils To better understand the change in geotechnical properties of highly plastic fine-grained soil due to crude oil contamination and bioremediation, Atterberg limits, compaction, unconfined compression, direct shear, and consolidation tests were conducted on natural, contaminated, and bioremediated soil samples to investigate the effects of contamination and remediation on fine-grained soil properties Oil contamination reduced maximum dry density (MDD), optimum moisture content (OMC), unconfined compressive strength (UCS), shear strength, swelling pressure, and coefficient of consolidation of soil In addition, contamination increased the compression and swelling indices and compressibility of soil Bioremediation reduced soil contamination by about 50% Moreover, in comparison with contaminated soil, bioremediation reduced the MDD, UCS, swelling index, free swelling and swelling pressure of soil, and also increased OMC, shear strength, cohesion, internal friction angle, failure strain, porosity, compression index, and settlement Microstructural analyses showed that oil contamination does not alter the soil structure in terms of chemical compounds, elements, and constituent minerals While it decreased the specific surface area of the soil, and the bioremediation significantly increased the mentioned parameters Bioremediation resulted in the formation of quasi-fibrous textures and porous and agglomerated structures As a result, oil contamination affected the mechanical properties of soil negatively, but bioremediation improved these properties

Effects of oil contamination and bioremediation on geotechnical properties of highly plastic clayey soil

This paper aims at the development of a regression-aided analytical framework for modeling and analyzing the compressibility behavior of over-consolidated soils. A three-parameter rectangular hyperbola function (3P-RH) was proposed for describing the void ratio-effective stress relationship. Validation of the 3P-RH was carried out by a compiled database gathered from the literature. Simple analytical solutions were then proposed for determining the compressibility curve variables including the compression (C-c) and recompression (C-r) indices and the preconsolidation pressure (P-c), which are intended to replace the current subjective graphical method by providing consistent results. Equations for the preconsolidation pressure were derived in accordance with four common graphical constructions covering various levels of geometrical complexity (slightly to highly subjective). A probabilistic comparison among the graphical constructions was then carried out. Furthermore, a sensitivity analysis with respect to the proposed preconsolidation pressure functions was considered to evaluate the influence of the 3P-RH fitting parameters (alpha and beta) on the preconsolidation pressure value. The proposed 3P-RH compressibility model accompanied by the suggested analytical solutions for solving the compressibility curve variables construct a unique framework for modeling the compressibility behavior of soils with an acceptable degree of accuracy and, more importantly, by a simple objective approach.

/pdf/a-framework-for-interpretation-of-the-compressibility-3gm3h5or7u.pdf

A Framework for Interpretation of the Compressibility Behavior of Soils

Volumetric changes (usually swell) of expansive soils in presence of water are undesirable from stability reasons. Swell and Swelling pressure of an expansive soil is primarily dependent on the ini...

M. Munnas

Papers

Swelling behavior of expansive soils