"Вестник МГСУ"

The article covers the problem of applicability of finite-element and engineering methods to the development of a model of interaction between pipeline structures and the environment in the complex conditions with a view to the simulation and projection of exogenous geological processes, trustworthy assessment of their impacts on the pipeline, and the testing of varied calculation methodologies. Pipelining in the areas that have a severe continental climate and permafrost soils is accompanied by cryogenic and exogenous processes and developments. It may also involve the development of karst and/or thermokarst. The adverse effect of the natural environment is intensified by the anthropogenic impact produced onto the natural state of the area, causing destruction of forests and other vegetation, changing the ratio of soils in the course of the site planning, changing the conditions that impact the surface and underground waters, and causing the thawing of the bedding in the course of the energy carrier pumping, etc.
The aforementioned consequences are not covered by effective regulatory documents. The latter constitute general and incomplete recommendations in this respect. The appropriate mathematical description of physical processes in complex heterogeneous environments is a separate task to be addressed. The failure to consider the above consequences has repeatedly caused both minor damages (denudation of the pipeline, insulation stripping) and substantial accidents; the rectification of their consequences was utterly expensive. Pipelining produces a thermal impact on the environment; it may alter the mechanical properties of soils and de-frost the clay.
The stress of the pipeline is one of the principal factors that determines its strength and safety. The pipeline stress exposure caused by loads and impacts (self-weight, internal pressure, etc.) may be calculated in advance, and the accuracy of these calculations is sufficient for practical implementation. Stress and strain caused by other factors (groundwater supports, anchors, fixing elements) may only be identified on location. The impact of other factors (temperature, permafrost thawing, karst phenomena and landslides, etc.) may be identified as approximate values.

It has been known that the use of karst stability categories classified by sinking diameter and the rate of its occurrence creates contradictions between researchers and designers. These contradictions are most discernable when implementing special projects such as construction of linear objects. The article provides an example of risk management when placing linear objects on karsted territories as exemplified by trunk line submerged crossings in a valley of a large transit river. The conditions of the regional karst development were identified, as well as the features determining sink risk. The authors provide the factual material analysis using the concepts that describe the reasons for the formation sink mechanism. The risk assessment is carried out during the analysis of necessary and sufficient conditions for the occurrence of sink mechanisms forming the karst hazard. The research results showed that the seasonal variations influence the possibility of karst risk. It is proposed to use an algorithm of karst management based on the variability approach, taking into account the changes in environmental conditions that affect the essence of the danger existence.

The authors consider theoretical issues of the present-day interpretation and applicability of
the terms and concepts of the engineering geology and geoecology. The authors propose a new
approach to the formulation of definitions of the founding concepts of major categories of the engineering
geodynamics as the constituent part of the engineering geology. At the current stage of
development of the geoecology, the processes and phenomena typical for the geological environment
considered from the viewpoint of civil engineering are regarded as geoecological rather than
engineering and geological.
Examples of incorrect interpretation of these concepts of engineering geology replace the
study of the processes and phenomena of the engineering geology by the study of exogenous
processes in the upper zone of the earth crust. Negative processes underway in the geological environment
that are considered within the framework of the engineering geology should be assessed
as geoecological. The assessment of the present-day use of the term "geoecological processes and
phenomena" is based on the principle of indecomposability and unity of the geosphere. This fact
serves as the basis for the modern interpretation of concepts of engineering geology or geoecology
that relate to the geological environment and its use as the setting of construction works.
The authors demonstrate that the pollution of the atmospheric air or its transparency affect
structures. It causes changes in the hydrogeological conditions that may cause a flood or reduction
of the level of underground waters that influence the behaviour of bases of constructions.
Anthropogenic impacts that cause the temperature and chemical pollution of the subterranean hydrosphere
can lead to the dissolution of rocks, trigger karst processes, boost the speed of underground
waters, and, thus, trigger the mechanical suffosion in the sands. The concept of geoecological
processes and phenomena as the basic categories needs the assessment of the geological
environment when exposed to the anthropogenic impact.