Geological engineering survey is performed to obtain information on the present-day geological conditions of the territory of the projected construction activity. Lithological composition, geomorphological and hydrogeological conditions, as well as the composition, quality and properties of subsoils and ground water, along with geological processes, occurring in the geological section, usually constitute the information which is obtained through the implementation of geological engineering surveys. These data are required for design documentary elaboration.
Geological engineering survey may comprise the following types of work:
- collection, analysis and integration of the archive survey data;
- geological and geomorphological surveys;
- conducting research on mine openings and pits by hand and mechanical methods;
- geological and geomorphological investigations;
- hydrogeological surveys;
- cone penetrometer tests;
- geophysical survey;
- dynamic penetration tests;
- fieldwork on geological horizons;
- laboratory research of physical and mechanical properties of rocks, including the permafrost rocks;
- laboratory research on chemical composition of the ground waters and soil-water extracts;
- assessment of geological engineering conditions of the survey territory;
- assessment and forecast of slope stability;
- geological engineering mapping;
- advanced geological and hydrogeological modelling;
- preparation of office documentation and compilation of the technical report.
In the preliminary stage of any survey to be conducted within Moscow city it is required to submit necessary documents and to receive permission on the geological engineering survey implementation in Geonadzor of Moscow and to ratify them in the underground facility Department GUP Mosgorgeotrest, MOESK or others. In the final stage the results of the survey undergo an inspection by experts where their compliance with the Russian government requirements is examined.
One of the main kinds of work which are performed during the geological engineering survey is the drilling of shallow boreholes by special geological equipment. Drilling operations are generally conducted by drilling devices UGB-50-M, complying with the regulations based on the preservation of the soil cover. Areas which are inaccessible for machinery are drilled by hand driller. In the majority of occasions mechanical drilling is used. The description and documentation of the geological profile as well as the sampling of the soils of undisturbed and disturbed structures are performed during the survey. The number and content of the samples taken are determined by the lithological variety of the subsoils and the potential variability of physical and mechanical characteristics both in plan and profile. All rocks extracted from the excavation are described.
Application of cable-tool drilling, core drilling and hand drilling provides the efficient study of rock composition and properties. It also gives the opportunity to establish boundaries between layers. Moreover, hydrogeological works, such as determination of ground water level and discovery of aquifers, are also implemented.
Along with the mechanical drilling, examination of relief and recent geological processes, which are the most influential in terms of the design and construction activity and environmental impact assessment, are performed during the survey work. It is not unusual that the results of such surveys become essential factors in reaching the design decisions or determining the viability of engineering measures in geomorphological conditions. They also allow surveyors to foresee natural and human-related risks. The main goal of these works is the compilation of geological and geomorphological descriptions and assessment of geological and engineering conditions of the survey area.
The cone penetration method is used for determination of rock durability characteristics within a survey area mainly formed by sand of great thickness. Adjustment of the layer boundaries of different lithological composition, indication of the average durability and deformational properties of the rocks as well as bearing power of the rocks in the natural deposits are conducted in compliance with the results.
The dynamic penetration test is meant to be used within difficult-to-reach areas. The data obtained through this tool is in line with the laboratory results and provide the information on bearing power rock properties in the natural deposits.
All types of work are implemented in compliance with the applicable regulations for reference documentation and meet the government standards of the Russian Federation (SNiP 11-02-96, SP 11-105-97; MGSN 2.07-01; SP 50-102-2003 and others), including the regulations concerning HSE requirements (SNiP 12-03-2001 and others).
Specialists of the «Institute of Environmental Survey, Planning and Assessment» participated in the following works:
- construction of the highway М-5 «Ural»;
- extension of Novomoskovskaya regional power station;
- construction of the power generating unit of CHP-20;
- reconstruction of airfield Uljanovsk «Vostochnij» (Uljanovskaya region);
- geological exploration of the deposits Novoportovskoy ploshady (the Yamal-Nenets Autonomous District).