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5CENTRAL ASIAN RESEARCH JOURNAL FOR INTERDISCIPLINARY STUDIES (CARJIS) ilmiy jurnali bilan hamkorlikda. IMPROVING THE METHOD OF CALCULATING THE STRENGTH OF AN UNDERGROUND PIPELINE ON THE BASIS OF WAVE PROPAGATION
THEORY. Baratov Nuriddin Maxmudjonovich, student, NamECI, Namangan nurik8823@mail.ru ANNOTATION
A brief analysis of the calculation methods for assessing the earthquake resistance of underground pipes, their advantages and disadvantages are presented in the article. The analysis of soil interaction models under the seismic (dynamic) influence of underground pipes is presented. Underground Pipe-Soil Problems the interaction is established in the propagation of seismic waves in the installed tubular soil environment. One-dimensional The method solves a number of non-stationary wave problems for the soil environment and the pipeline characteristics and method of finite differences. Digital solutions are obtained in the form of change.
Keywords: Engineering, underground, problem, economic, especially, seismic, currently, SNiP 2.05.06-85* (RF) and in Uzbekistan (KMK 2.01.03-96).
Introduction. Usage of underground pipelines, which make up some of the most important backbone systems for any population, including water, gas, and oil pipelines, has been on a rise all over the world. Their stability under various conditions (seismic ones, landslides, mudflows, transport and sea accidents, etc.) becomes a particularly urgent problem, since a rise in accident rate of underground pipelines leads to large economic and environmental losses. To prevent this damage, it is necessary to determine the causes of underground pipeline damage under dynamic loads of different nature. Studies of underground pipeline strength and stability under static and dynamic loads have a long history and have been carried out by many researchers all over the world. The most significant results of the studies are given in. Based on the results given in, the process of the stress state formation, which affects the strength of underground pipelines under dynamic (especially, seismic) loads, is a very complicated one as there are a lot of factors which define the basic determinant indices of this process. In the life support system for the population, the pipes made from various materials and of various configurations are widely used as water pipelines, gas pipelines, oil pipelines, for transportation of toxic and explosive substances in various industries and manufactures. Pipelines are widely used in the cities, between the cities and populated localities and in the recent decades have been widely used between the countries. Therefore, pipelines are often called "life lines" and this shows, that pipelines play an important role in human life. Due to the enormous length and wide geographical distribution, the pipelines are located at different laying depths in complex ground conditions and under water, in cross profile areas with tectonic faults
CENTRAL ASIAN RESEARCH JOURNAL FOR INTERDISCIPLINARY STUDIES (CARJIS) ilmiy jurnali bilan hamkorlikda. and in zones of different seismic intensity; they are exposed to great exploitative and seismic hazard. Due to the fact that pipelines play a significant role in country's economy, much attention has been paid to their reliable operation, ensuring their seismic safety during the exploitation.
Methods. Currently, there are three basic methods to determine longitudinal seismic stresses in underground pipelines. As described in [9] the first method is based on the hypothesis of the equality of longitudinal strains in the pipeline and soil under seismic loading. Here, the seismic load is taken in the form of plane elastic wave propagating in soil, changing according to a sinusoidal law. Such a statement allows analytical determining the maximum elastic strain in soil [9]. It is assumed that an underground long pipeline receives the strain equal to the maximum elastic strain of soil. Longitudinal stress is determined from Hooke's Law at a known longitudinal pipeline strain. This simple method is laid as the basis for determining longitudinal seismic stresses in the regulatory documents (Building Code) in the Commonwealth of Independent States countries (SNiP 2.05.06-85* (RF) and in Uzbekistan (KMK 2.01.03-96). It is obvious that under seismic waves propagation in soil medium with embedded pipeline, the longitudinal strain of the pipeline cannot be equal to the soil strain, as it is assumed in.
Analysis and results: The results of experimental studies of physico-mechanical properties of the centrifuged and vibrated samples were given in. The properties of inhomogeneity of a fresh concrete mix were evaluated to determine the changes in water-cement ratio, residual water content and density along the thickness of the centrifuged sample, as well as the changes in strength properties of hardened concrete. As a result, a numerical experiment to study the carrying capacity of the centrifuged supports of the power lines was conducted, taking into account the obtained dependence of the change in concrete strength along the wall thickness of the product. In, an issue of temperature wave propagation along the wall of the hollow cylinder with an abrupt change in temperature of internal medium arising from the motion cessation or circulation of a heated flow was considered. An algorithm for calculating the temperature field by a numerical method was shown using an explicit finite-difference scheme of enhanced accuracy under cylindrical symmetry conditions, under boundary conditions of the first kind. The results of calculation of the temperature wave penetration depth were given by the considered algorithm depending on time passed after thermal effect. The results of numerical solutions of underground and aboveground structures spatial problem taking into account the work of the surrounding infinite massif in homogeneous and inhomogeneous areas were given by a combined method.
Conclusion. Experimental studies of polymer pipes under temperature effect have been carried out on a modernized centrifugal installation of the Institute of
CENTRAL ASIAN RESEARCH JOURNAL FOR INTERDISCIPLINARY STUDIES (CARJIS) ilmiy jurnali bilan hamkorlikda. Mechanics and Seismic Stability of Structures of the Academy of Sciences of the Republic of Uzbekistan. The existing measuring complex based on the light-beam oscillographs was replaced by a new recording system "sensor + amplifier + analogous digital converter + personal computer + software". The created program of sensor signals registration allowed us to avoid the use of photographic paper and chemical processing, to significantly reduce the processing time and to observe the experiment in real time on the computer monitor. The results of instrumental measurements in numerical and graphical form are given immediately after the end of the experiment. The data obtained during the experiment are saved as files and can be reused later.
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