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The geotechnical characteristics of hydrocarbon-contaminated soils have been concentrated heretofore due to the alarming frequency of hydrocarbon contaminations and also their significant consequences. Over the past three decades, numerous research studies have been conducted in order to investigate hydrocarbon-induced changes in geotechnical properties of soils. The present article is aimed at extensively reviewing almost all relevant academic literature to this subject, and, due to various kinds of soils and hydrocarbon compounds, it tries to provide a brief summary of each research study along with its key findings as well. By this review, it was revealed that geotechnical characteristics of soils such as particle size distribution, Atterberg limits, permeability, optimum moisture content, maximum dry density, compression index, coefficient of consolidation, over-consolidation ratio, cohesion, angle of internal friction, unconfined compression strength, shear strength, and so on can be remarkably influenced by hydrocarbon contaminations. However, the amount of these hydrocarbon-induced changes were highly dependent on various factors including soil and hydrocarbon properties, environmental and operation conditions, weathering process, etc. so that, for each specific geotechnical property, various alterations were reported in scientific literature.Response: With regard to this reviewer's comment ("years from old to new"), it should be stated that the authors used EndNote X8 software for organizing the references along with the specific EndNote style available in the journal's website (www.springer.com/earth+sciences+and+geography/engineering+geology/journal/1006 4?detailsPage) which determines/implements all the references automatically. However, the reference of UNEP was corrected throughout the manuscript.2. P5L31-32, why a symbol (a) here?Response: "Benzo (a) pyrene" was replaced by "benzo[a]pyrene". Benzo[a]pyrene is a polycyclic aromatic hydrocarbon with the formula of C20H12 which is one of the benzopyrenes, formed by a benzene ring fused to pyrene.3. P6L29-30, delete the term "by the authors" and "Precisely speaking" in L34.Response: These phrases were omitted. 4. P7L46-47, delete the sentence "Based on the information presented by Chang et al. (2014)" and add the referee (Chang et al. 2014) at the end of the sentence.Response: Thanks to this reviewer's comment, the mentioned phrase was deleted, and the relevant reference was embedded at the end of the paragraph. 5. P8L7-15, try to simply this long sentence here.Response: The long sentence was properly outlined. 6. P11L2-3, do not use the term "something along those lines." Response: The phrase was deleted. 7. P24, please number the equations and add () for the unit (%). Response: The number and parentheses were added. 8. P26L34-36, delete "see also," and replace (Jia et al. 2010) by (2010).Response: The mentioned corrections were implemented 9. P27L53-54, delete "see also," and the outer ().

The elastic behaviour of compacted soils subjected to very small strains (smaller than 10 -5 ) is essential, because the serviceability of most geotechnical structures depends on soil elastic properties. Small-strain stiŠness of soils was studied in the past years using diŠerent experimental devices (mainly resonant columns). However, the results have been relatively inconsistent. The bender elements technique, now extensively used in soil mechanics, oŠers an e‹cient non destructive alternative, since it is based on the propagation of shear waves. To enrich the common bender elements testing results providing only shear modulus values, an evolution of the bender elements technique, named bender-extender element's is used in this paper. This device allows the simultaneous measurement of the shear and compression wave velocities. As a result, the two independent elastic constants are measured for the same sample in order to avoid indirect estimations. Also, for unconˆned sample's the GrindoSonic test is performed: this test is based on the transient vibrational response of the sample to a slight shock. The present study provides new results about the elastic properties of intermediate unsaturated soils made of mixtures of sand and clay. The results for the elastic properties are presented as a function of the suction level. Finally, a model relating the elastic behaviour of these unsaturated soils is proposed.

The engineering characteristics of hydrocarbon-contaminated soils have been precisely concentrated so far. However, besides influential effects of weathering on hydrocarboncontaminated soils, a substantial majority of these studies have been devoted to short-term analyses. By the same token, the present paper aims at comparing short-and long-term effects of light crude oil contamination on maximum shear modulus (G max) of two sand (Ottawa and Firoozkooh sand). To this aim, a series of bender element tests was conducted on both newly and aged contaminated sand samples under identical circumstances so as to characterize short-and long-term influences of the hydrocarbon contamination on G max. In the short term, G max of Firoozkooh sand was more sensitive to the contamination compared to Ottawa sand; however, the tendency of their responses was almost similar so that presence of 4 wt.% of crude oil into both sand types could greatly increase the value of G max , and adding further contamination made markedly negative changes in G max to some extent that G max of both 8 wt.% contaminated sand types was lower than that of clean ones. Furthermore, G max of both sand types were not sensitive to adding more crude oil (≥8 wt.%). Generally, in the long term, weathering process could obviously increase the value of G max of both sand types such that the changes were more detectable during the first 6 months, and more importantly, the majority of these alterations took place in the first 2 months. Additionally, in contrast to short-term findings, contaminated Ottawa sand samples were more sensitive to weathering process, and the degree of weathering effects on G max was more observable in 4 wt.% contaminated samples of both sand types in comparison with specimens containing 8 and 12 wt.% of crude oil.

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Click here to view linked References velocity of 4 wt.% contaminated sand (V s−4 wt.%) was about 1.2 times higher than clean one (V s−clean), and contrastingly adding further crude oil up to 6 wt.% made a significant reduction in value of shear wave velocity to some extent that V s−6 wt.% was slightly lower than V s−clean (V s−6 wt.% =0.95-0.97V s−clean). Moreover, adding more contaminant (8-12 wt.%) into sand had negligible influences on shear wave velocity. In this paper, the effects of crude oil contamination on sand microstructure were also evaluated using scanning electron microscopy.

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