scholarly journals INTERACTION OF POST FOUNDATIONS AND FROZEN SOILS

2020 ◽  
Vol 17 (5) ◽  
pp. 96-113
Author(s):  
A. I. Marasanov ◽  
A. A. Sheikin ◽  
I. V. Sheikin
Keyword(s):  
Strain State ◽  
Soil Layer ◽  
Frozen Soil ◽  
Depth Range ◽  
Stress Strain ◽  
Engineering Structures ◽  
Frozen Soils ◽  
Railway Line ◽  
Stress Strain State ◽  
Behavior Study

The frozen soils’ stress-strain state varies with time due to the internal soil rheological processes. Those processes become active within the thawing period of the active soil layer causing increase in settlement of the engineering structures’ foundations. Hence, creep processes and thawing of frozen soils should be considered when designing the transportation facilities for regions of the Far North and Siberia.The objective of the research is to develop a procedure for evaluating the variation in time of the stress-strain state of the frozen soil under the post footing of a bridge pier’s foundation considering the frozen soil creep and thawing. The interaction of the bridge pier post foundations and frozen silt-loam soil is modelled and studied. The research is based on the example of an existing overpass over the M‑56 Lena motor road situated at Amga–Samyrdah stage of Tommot–Yakutsk section of the Berkakit–Tommot–Yakutsk railway line. This overpass has piers with post foundations. The above railway line is in the area of hard frozen soils.The study focuses on changes in principal normal compressive stresses with the course of time, as well as on the frozen soil movements under the post footing. The time allotted for the above system behavior study is limited to five months. There are two design cases: a) considering the frozen soil thawing up to a depth range of 1,5 to 4 m; b) without considering the frozen soil thawing.The research has shown that the thawing of the frozen soil up to a comparatively low depth as compared to natural level results in a significant increase (by 2÷2,5 times) in the values of post foundation settlement as compared with the design case without thawing. At the same time, it was found that small values of thawing have a subtle effect on the frozen soil’s stress state under the post footing. Besides, all reviewed design cases (with / without thawing revealed that stress of the frozen soil under the post footing decreases with time (stress relaxation).

scholarly journals MODELLING OF THE EFFECTS OF THE ENVIRONMENTAL-GEOPHYSICAL STATE OF SOILS ON ENGINEERING BUILDING OBJECTS

2020 ◽  
pp. 97-103
Author(s):  
Yu. Starodub ◽  
A. Havrys ◽  
O. Kozionova
Keyword(s):  
Strain State ◽  
Mathematical Formulation ◽  
Soil Layer ◽  
Soil Mass ◽  
Negative Influence ◽  
Stability Study ◽  
Bridge Engineering ◽  
Stress Strain ◽  
Engineering Structures ◽  
Stress Strain State

The article deals with the method of the reaction modelling of soil strata under engineering objects to ecological and geophysical state in the problems of studying the negative influence of loads on a stress-strain state of soil under engineering objects. The problem of stability study is considered and the behaviour of soil in a vicinity of bridge-engineering structures is investigated. To solve the problems of emergency protection, a method of modelling the reaction of the soil layer under the load on the engineering objects due to tectonic influences to study the stress-strain state of the ground crust in a vicinity of engineering objectsis used. An algorithm of the finite element method in the problem of studying the stress-strain state of soil base under engineering objects has been developed. The physical and mathematical formulation of the problem is carried out. The modelling problem is solved by test cases. Models of continuous environment of functioning engineering structures for which stress-strain characteristics of the soil massif modelled are developed. The theoretical definition and modelling of critical values of the stress-strain state of the soil mass under the influence of loads are carried out. Modelling allows to predict the nature of the influence of mechanical processes on the ecological and geophysical state of the environment and to study the stability of engineering structures. Stress-deformation processes of the rock massif are investigated, as a result of which emergencies of natural and man-made characters can arise.

scholarly journals SIMULATION OF DISPLACEMENT OF LANDSLIDES ON THE MATERIALS OF GEODESIC OBSERVATIONS AND ENGINEERING-GEOLOGICAL SURVEYS

2021 ◽  
Vol 26 (2) ◽  
pp. 5-17
Author(s):  
Alexandra A. Islyamova ◽  
◽  
Valery S. Khoroshilov ◽  
Keyword(s):  
Strain State ◽  
Open Pit ◽  
Published Data ◽  
Successful Implementation ◽  
Stress Strain ◽  
Engineering Structures ◽  
Stress Strain State ◽  
Geological Surveys ◽  
Landslide Body ◽  
Simple Slope

The article discusses the possibilities of applying modeling of the stress-strain state of slopes to predict landslide hazard, which is very important for the successful implementation of all subsequent stages of design, construction and operation of engineering structures. The article considers the exist-ing approaches and methods used in the process of solving the problem, and determines the study as the type of mathematical modeling of the stress-strain state of a landslide body by the finite element method. It is shown that the selection of specific mathematical expressions for all subsequent calcula-tions is carried out depending on the specific type of landslide. The mechanisms of deformation and destruction of the slope under the action of gravitational forces are shown using the data of geodetic observations and engineering-geological surveys. As a result of the studies performed, calculations were made on several models illustrating the behavior of the soil massif of a landslide-prone slope. Stress patterns were obtained for a simple slope with a steepness of 35°, which coincide with the pre-viously published data of the physical experiment for the real open pit slope.

scholarly journals Stress-strain state of the building foundations with taking into account the possible water saturation of loess soils

2020 ◽  
pp. 22-31
Author(s):  
Veronika Zhuk ◽  
Oleksandr Piatkov ◽  
Sergiy Tarambula
Keyword(s):  
Strain State ◽  
Water Saturation ◽  
Cost Effective ◽  
Loess Soil ◽  
Soil Base ◽  
Stress Strain ◽  
Engineering Structures ◽  
Load Bearing ◽  
Stress Strain State ◽  
Loess Soils

In Ukraine, the problem of construction on loess soils is relevant due to the widespread use of these soils and their negative property - the ability to give additional deformations of subsidence during water saturation. Flooding of territories by groundwater, emergency leaks from aquifers cause significant problems during the exploitation of buildings and engineering structures on such soils. Computer simulation of the interaction of the building with the soil base allows to investigate the influence of all negative factors on the change of the stress-strain state of both the soil base and the load-bearing structures of the building. The study of the interaction of the building with the foundation was performed using the software package LIRA-CAD. The interaction of the building with the soil base, the soils of which are able to reduce their mechanical properties with increasing humidity and give additional subsidence deformations, was studied. A variant design of the foundations was performed taking into account the occurrence of uneven deformations during subsidence of the loess soil due to its moistening in case of possible emergency losses from aquifers. The change of stress-strain state of the foundations of the building depending on the spatial rigidity of the foundation, the location of the soaking zone within the building spot, the shape and size of the zone of soil moisture is analyzed. It is shown that taking into account the possible water saturation of loess soils when calculating the collaborate of the building with the soil base, allows to obtain stress-strain state of foundations and load-bearing structures of the aboveground part of the building for the most unfavorable conditions that may occur. The search for the optimal variant of the foundation structures of the building, which, while remaining cost-effective, provides reliable operation of the building in conditions of possible occurrence of uneven deformations of subsidence of the soil base during water saturation of the layer of loess soils. According to the research results, a rational variant of the foundation structures has been designed taking into account the possible occurrence of non-uniform deformations.  

scholarly journals Calculation of thermal stress-strain state of soil base under the building on permafrost soil

2019 ◽  
Vol 97 ◽  
pp. 04056
Author(s):  
Mikhail Rabinovich
Keyword(s):  
Strain State ◽  
Negative Temperature ◽  
Frozen Soil ◽  
Permafrost Soil ◽  
Test Problems ◽  
Soil Base ◽  
Stress Strain ◽  
Temperature Spectrum ◽  
Stress Strain State ◽  
Permafrost Soils

Article presents problem statement and solution for joint calculation of temperature regime and stress-strain state of permafrost soils under building footing, with consideration of thermal impact from on-surface and buried high-temperature utilities. Based on a series of optimization tasks, a design model for stress-strain state has been developed, solutions of test problems have been obtained and analyzed to determine the degree of influence of temperature stresses and relation of the deformation characteristics of frozen soil in the negative temperature spectrum on the stress distribution and settlement values of frozen soil base under the building.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

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