Construction and Geotechnics

The object of the research is the compressibility of the marine soft clayey soils from the coastal territory of the White Sea. Such soil types are widespread at the coastal territories around the world. The study is devoted to analysis of dependence of a compression index сс on a void ratio and a water content. Statistical data analysis of the long-term oedometer tests of 59 undisturbed samples taken from a depth of 12-18 meter was performed. The following intervals of a compression index for three types of soils with different content of particles d < 0.05 mm was defined: 20-30 % - 0.067-0.087; 30-40 % - 0.072-0.332; 50-60 % - 0.109-0.439. The linear correlation of the compression index with an initial void ratio e0 and a natural water content W was obtained: cc = 0.351 e 0 - 0.226 ( R 2 = 0.75); cc = 0.896 W - 0.188 ( R 2 = 0.73). The latter equation is more useful for soil exploration because the auger boring can be used for sampling of disturbed probes. The review of more than 30 empirical equations showed that the parameters of linear relationships obtained by us are typical for coastal soft clayey soils. The obtained equations can be used in a numerical simulation and to estimation an oedometer modulus for the traditional methods of settlement calculation. The secant oedometer modulus and tangent oedometer modulus are computed through a compression index at the end of article.

At present, our country is actively engaged in the development of the natural resources of the Far North. In this regard, the issues of construction in harsh climatic conditions and the issues of ensuring the safety of workers' residence become important. In the Far North, the construction of stationary buildings is not economically profitable. Therefore, the priority is given to the use of block-containers, since most of the work is carried out on a rotational basis. They are easy to transport to the place of installation, they are adapted for operation at low outdoor temperatures. The outer enclosing structures of such containers are made of foam materials with a thickness of 150-200 mm. A significant disadvantage of such containers is that in the event of an accident or shutdown of the heating system, the temperature in the container drops very quickly, which leads to emergency situations. The article proposes a new way to increase the thermal inertia of an external enclosing structure designed for operation in harsh climatic conditions. It is proposed to place moisture with a high heat capacity inside the outer enclosing structure made of foam material. At the point where the zero isotherm passes, which is determined by calculation, a heat-accumulating insert is placed in the plane of the wall panel, made of plastic pipes of a rectangular or square section of a certain size. The pipes are filled with water, forming in the wall panel, as it were, an additional layer of pipes filled with water. In the event of an accident or shutdown of the heating system, the water in such pipes will play the role of a damper to restrain the heat flow into the environment. In this case, the heat of the phase transition inside the pipes will be used. The calculations show that the use of a heat storage insert can significantly increase the survivability of the container unit and gain time to repair the heating system, and, consequently, make the work and living of workers in low temperatures safer.

The object of research is the stress-strain state of protective and decorative coatings of external enclosing structures. The purpose of the research is to evaluate the stress-strain state of protective and decorative coatings under the action of temperature, depending on the porosity of the substrate, the thickness of the coating. The article presents the results of the calculation of stresses depending on the thickness of the paint coating, the size of the pores in the contact zone "coating-substrate". The SCAD Office software module was used to assess the stress state of the coatings. A comparison is made of the stresses in the coating when pores of different radii are filled with a paint composition and in the absence of pore filling. It has been established that under the action of an alternating temperature in the coatings, a change in the deformed state occurs, characterized by alternation of compressive and tensile stresses. The magnitude of internal stresses decreases with decreasing coating thickness. With a decrease in the radius of the pores filled with the ink composition, the stresses in the zone of contact between the coating and the substrate decrease, and in the center of the pore filled with the ink composition they increase. As the pore radius decreases, the difference between the stress values on the coating surface and in the zone of contact between the coating and the substrate decreases. There is a change of signs of stresses in the zone of contact between the coating and the substrate and in the center of the pore filled with the ink composition. Recommendations are given for choosing the type of paint.

This publication raises the currently relevant problem of the surfacing of trunk pipelines. The main methods of ballasting pipelines passing through water barriers are considered. According to the requirements of the regulatory documentation, formulas for the dependence of the required volume of materials on the length of the section, as well as formulas for the dependence of the cost of the materials in question on the length of the section of the main pipeline, are derived analytically. These dependencies are presented graphically. The analysis was carried out for pipelines with a cross section of 325 ´ 8, 720 ´ 10 and 1440 ´ 12. This pipeline passes through water barriers. Calculations were performed for reinforced concrete weights of the ring type UTK, cast-iron weights of the ring type UCHK, as well as solid concreting with concrete of strength class B15. As a result, the most economical method of pipeline ballasting was obtained under the considered engineering and geological conditions.