BIOTIC COMPONENT OF CLAYSOILS

All kinds of micro- and macroorganisms live in the massifs of clay soils: plants living in (or on) clay soils are called pelitophytes (from the Greek πηλός - “clay” and phyton - “plant”), micro- and macroorganisms living in clays, or associated with clays, they are called pelitophiles (from the Greek πηλός - "clay" and φιλία - "love"), that is, "loving clays" or "prone to clays." The article analyzes these groups of organisms and describes their role in the formation of the properties of clay soils and ecological-geological systems.

ON STANDARDIZATION OF LABORATORY SOIL TESTING IN OFFSHORE GEOTECHNICAL SURVEY

Issues of laboratory soil studies standardization in offshore geotechnical survey are discussed in connection with the end of expertise of two new regulative documents – new edition of the Code of practice and Russian national standard developed on the basis of international ISO standard. Since these documents of different level belong also to different categories (geotechnical survey and oil and gas industry), the authors analyze their interrelation and consistency, from one hand, and the preparedness of Russian soil testing practice to implementation of the new standard which results from harmonization with international ones, from the other. Complete section of the standard draft related to soil laboratory testing is presented, preceded by commentary on some important issues regarding the implementation of its specific methodic statements. It is concluded that the new national GOST draft «Petroleum and natural gas industries. Specific requirements for offshore structures. Marine soil investigations» developed on ISO basis will be a useful document supported in general by Russian normative base but expanding a possible range of voluntary methods into well time-tested foreign approaches. This documents can be considered to be a toolkit annex to the Code of practice describing testing approaches beyond the scope of typical tasks

CONE PENETRATION TESTING AND SAMPLING OF FROZEN SOILS

The article provides the analysis of the results of the permafrost soils field and laboratory tests. The undisturbed permafrost samples were collected using cone penetration testing (CPT) equipment and MOSTAP sampler. The sampling technology using CPT equipment was applied on permafrost soils for the first time. The full scope of tests for physical properties were carried out on the collected samples. Based on the test results, several engineering-geological elements (EGE) were identified and confirmed, one of which is composed of frozen silty clay. The results of statistical data processing were compared. The data on the coefficient of variation of the values of the ultimate long-term resistivity of soils against cone penetration (characteristic of long-term strength) for the frozen EGE are presented.

METHODIC ISSUES OF VIBRATIONS MEASUREMENTS FOR EVALUATION OF THEIR IMPACT ON SOIL MASSIFS

The paper is aimed at the attraction of attention of geologists, project engineers and those who operate engineering structures to the necessity of considering real parameters of technical vibrations from various sources in evaluation of the existing and designed soil bases as well as in methodic questions of these parameters’ measurements. In this connection the paper discusses present state of knowledge in measurement and evaluation of vibrations impact on natural and artificial soil massifs along with a brief presentation of theoretical basis of modern vibrometry. It also presents a variant of vibrations classification and discusses engineering geological and geophysical research methods for evaluation of soil behaviour under the influence of vibrations. Information from such studies is analyzed on the example of vibration loads from railway. In conclusions the paper also mentions some important issues of standards for vibration measurements development.