scholarly journals Numerical analysis of methods for calculating the soil base and methods for determining bed coefficients

2020 ◽  
pp. 64-71
Author(s):  
Iryna Zhupanenko
Keyword(s):  
Poisson’S Ratio ◽  
Strain State ◽  
Deformation Modulus ◽  
Calculation Model ◽  
Poisson's Ratio ◽  
Soil Conditions ◽  
Soil Base ◽  
Stress Strain ◽  
Stress Strain State ◽  
Pasternak Model

Despite significant progress in the development of methods for calculating the soil base in a single calculation model with structures and the ability to perform calculations in three dimensions, the most popular in the community of design engineers remains the calculation model of the slab on an elastic basis. This is due to the simplicity of such a model. Probably, the greatest difficulty in applying such a model is to determine the coefficients of flexibility of the base (bed coefficients). In this paper, a study of the reliability of different methods for determining the coefficients of the bed under different variants of soil conditions The paper determines and compares the characteristics of the stress-strain state (sedimentation values, reactive pressure and forces) in three foundation slabs of different geometry and under different engineering and geological conditions of the construction site. A homogeneous base composed of loess soils, an inhomogeneous base composed of alternating layers of both cohesive (loam and sand) and incoherent (fine sand) soils and a close to homogeneous base composed of sand and soils are considered. The research was conducted using the software and computer system LIRA SAPR 2016. Implemented three methods for determining the coefficients of the bed (the flexibility of the base): - Pasternak model with two bed coefficients, which for inhomogeneous soils are determined by the values of the deformation modulus and Poisson's ratio averaged within the depth of the compressible thickness; - Winkler model with one bed ratio; - Pasternak model with two bed coefficients, which are determined by the average values of the deformation modulus and Poisson's ratio when introducing the correction factor to the deformation modulus. The convergence of the absolute values of the controlled parameters obtained using the above methods, depending on the type of soil base and the nature of soil layers within the compressible layer, is analyzed. The dependence of the convergence of the characteristics of the stress-strain state of the slab obtained by different methods on the homogeneity of the base soils is established.  

scholarly journals Investigation of hydrogeomechanical parameters of loess massifs in conditions of technogenic underflooding and development of technical recommendations for strengthening of bases of foundations

2019 ◽  
Vol 28 (1) ◽  
pp. 173-179 ◽  
Author(s):  
I. O. Sadovenko ◽  
A. M. Puhach ◽  
N. I. Dereviahina
Keyword(s):  
Strain State ◽  
Quantitative Estimation ◽  
Residential Buildings ◽  
Finite Element Approximation ◽  
Element Approximation ◽  
Soil Base ◽  
Stress Strain ◽  
Elastic Mode ◽  
Stress Strain State ◽  
Water Saturated

Based on the analysis of actual data and the results of numerical modeling, dependencies of deformations of the investigated residential complex due to technogenic moistening of a loess massif of soils are investigated. It was established that a dynamics of subsidence of bench marks in time is closely correlated with a moistening mode. In order to form a picture of dynamics of development of moistening phases of the massif and a quantitative estimation of main factors of their formation, a numerical model of the loess massif was built, based on the finite element approximation of the section of built-up area of the residential complex. Stability of a soil massif was estimated by the character of development of plastic deformation zones. Analysis of a stress-strain state of a rock massif indicated that water-saturated soils are partially in a state of plastic flow in a base. The development of shear deformations is most characteristic within a zone of the main moistening, as well as a boundary of its front. Development of rupture disturbances at the edge of the contour of buildings corresponds with the formation of tear cracks. An intensification of subsidence of buildings with simultaneous frontal and subvertical technogenic moistening of loess soils can be noted. Model estimations of a stress-strain state of the pile foundation, considering the uneven subsidence that occurred along the perimeter of residential buildings, show that the elastic mode of their deformation has not been exhausted. Options of redistribution of loads from residential sections onto an additional pile field, regulated base moistening and grouting of soils are considered as engineering measures to prevent further deformation of the residential complex. Stabilization of a soil base by means of high-pressure cementation is the most acceptable in the present conditions. Technological scheme of cementation of the soil base is recommended, as well as measures after the base stabilization, such as monitoring of further deformations of the complex itself and parking structures, and possibilities of constructing auxiliary drainage.

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 Influence of the sequence of erection of build-ings on the formation of the stress-strain state of the system «base-foundation-overhead structures»

2020 ◽  
pp. 32-44
Author(s):  
Liudmyla Skochko ◽  
Artem Shabaltun
Keyword(s):  
Strain State ◽  
Design Parameters ◽  
Soil Base ◽  
Stress Strain ◽  
High Rise ◽  
Stress Strain State ◽  
Subsequent Section ◽  
The Impact ◽  
Ground Structures ◽  
Formulation Of Problems

The influence of the order of construction of houses on the formation of the stress-strain state of the system "foundation-foundation-above-ground structures" is investigated For this purpose, several options for setting tasks for the phased construction of multi-section building sections are considered. With this in mind, it should be noted that the construction of each subsequent section has an impact on the built entirely or partially adjacent section. That is why this effect should be investigated to predict how serious this impact may be, and to draw appropriate constructive decisions. Thus, the main objectives of the study are: Creation of SEM without taking into account the stages of construction of the house; Calculation of a house with a phased loading of 5 floors. Taking into account changes in the order of construction of sections; Formation of SEM taking into account the sequence of erection of sections without including the sequence of erection of floors within the boundaries of the current section; Research of the impact of the calculation of sections of a multi-section building without and taking into account the summary of subsequent sections. The research of the impact of the sequence of construction and installation of the object will allow us to assess the stress-strain scheme at all stages of construction, so changes in the behavior of the scheme will be recorded at all stages of construction specified by the designers. To do this, the change in the stress-strain state (VAT) of the system "foundation - foundations - above-ground structures" must be modeled with different options for stages of construction, taking into account the real parameters of the soil base and so on. The interaction of piles in different zones of sections, the work of grids in the foundations of high-rise buildings are considered. The research was carried out with the help of numerical modeling of the system "foundation - foundations - aboveground constructions". The redistribution of forces in the piles depending on the formulation of problems on the stages of construction of sections and design parameters (location of piles in characteristic zones, the influence of the stiffness of the aboveground part on the redistribution of forces). Characteristic zones in the foundation are distinguished: they are central, lateral, angular and especially at the joints of adjacent sections. The redistribution of efforts between piles and a grid is revealed.  

scholarly journals Strength assessment of earth dams

2019 ◽  
Vol 265 ◽  
pp. 04015 ◽  
Author(s):  
Tokhirjon Sultanov ◽  
Bakhtiyor Yuldoshev ◽  
Elyor Toshmatov ◽  
Javlonbek Yarashov ◽  
Rustam Ergashev ◽  
...  
Keyword(s):  
Spatial Model ◽  
Strain State ◽  
Static Load ◽  
Comparative Method ◽  
Calculation Model ◽  
Earth Dams ◽  
Stress Strain ◽  
Strength Assessment ◽  
Stress Strain State ◽  
Assessment Of Stress

A comparative method for estimating the stress-strain state of earth dams under the effect of static load is given in the paper using spatial and plane-strain models. The results of assessment of stress-strain state of several earth dams using these methods are given. Analysis of the results obtained allows us to conclude that a plane calculation model gives results almost identical to the ones obtained with spatial model; in future that can be the basis for developing recommendations on the use of certain calculation models. Some features of stress state in a spatial case are revealed, indicating the occurrence of dangerous areas with the greatest stresses.

scholarly journals Modeling of a piled foundation in a Femap with NX Nastran

2020 ◽  
Vol 16 (4) ◽  
pp. 250-260
Author(s):  
Elvira R. Kuzhakhmetova
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Pile Foundation ◽  
Strain State ◽  
Calculation Model ◽  
The Finite Element Method ◽  
Stress Strain ◽  
Foundation Soil ◽  
Stress Strain State ◽  
Building Foundation

Relevance. The underground part of the building (foundation and soil) has a significant impact on its stress-strain state and behavior under the influence of operational loads. Therefore, the existing regulatory and technical documentation regulates the design of buildings (structures), taking into account the joint work of their aboveground and underground parts. In practice, such accounting becomes possible on the basis of a comprehensive engineering analysis of the building as a large mechanical system building - foundation - soil, which today can be carried out using the finite element method. In the case of pile foundations, the correctness of the result depends largely on the reasonable choice of the design model of the pile-soil subsystem. The article analyzes three design models of piles operating in an array of soil foundation. The first model is discrete. In it, the pile is modeled by bars and is based on elastic supports (Spring) with generalized stiffnesses. Second model - spatial, in which the pile and soil are typed in by volumetric elements (Solid). Third model - spatial-bar or combined, in which the bar pile is embedded in the mesh of the soil mass using a rigid substructure formed by bars of high rigidity. The aim of the work - to determine a rational calculation model of the pile - soil subsystem, which allows, on the one hand, to reduce the general order of the system of resolving equations, and, on the other hand, to maintain the accuracy of the assessment of the stress-strain state of the calculation model of pile - soil and the building as a whole. Materials and methods. The numerical results of the analysis of the pile foundation statics using the three pile - soil calculation models were performed in the CAE software package - the Femap with NX Nastran class, which implements the finite element method. Results. Comparative-numerical analysis of the stress-strain state of the pile foundation - soil subsystem made it possible to determine the advantages, disadvantages, and also the areas of rational use of bar, spatial combined calculation models. In the next articles, it is planned to consider the calculation of piles for vertical loads, as well as a comparative analysis of numerical results with experimental data (in the labo-ratory or in field conditions) for horizontal and vertical effects.

scholarly journals Research of stress-strain state and stability of a rokfill dam under seismic actions

Vestnik MGSU ◽  
2015 ◽  
pp. 157-166
Author(s):  
Vyacheslav Valentinovich Orekhov
Keyword(s):  
Strain State ◽  
Initial Conditions ◽  
The Body ◽  
Cohesionless Soil ◽  
Soil Base ◽  
Stress Strain ◽  
Stress Strain State ◽  
Soil Skeleton ◽  
Water Saturated ◽  
Seismic Impacts

One of the main factors determining the safety of earth sea and river hydraulic structures erected on water-saturated grounds is the process of consolidation, manifested under the action of static and seismic loads. A feature of cohesionless soils located in the structure itself or in its base, is their potential ability to liquefaction under seismic impacts. This paper describes the method of calculating the saturated soil’s environments under seismic actions based on the numerical solution of differential equations of the theory of consolidation by finite element method. The results of the static problem solving for the phased construction of the installation are used as the initial conditions. In order to describe the deformability of soil materials mathematical model formed by the theory of plastic flow with hardening is used. The parameters of this model are determined by the results of triaxial testing of soils. As an example, we study the interaction of a sea rockfill dam with a sandy base under seismic impacts, determined by the synthetic accelerograms. The results of calculations of the stress-strain state of the two sections of the dam (shallow and deep) are presented, and assessment is made of the possibility of liquefaction of sandy soil base. It is shown that the pore pressure that occurs in water-saturated cohesionless soil base and the body of the dam under seismic impacts, unloads the soil skeleton, which leads to a decrease in local shear safety factors. And, in the less dense soil base of the shallow section of the dam, the soil skeleton is unloaded to a greater extent, which negatively affects its overall safety factor.

scholarly journals The stressstrain state of low-head dams’ basis on stratified soil

2016 ◽  
Vol 3 ◽  
pp. 4-9
Author(s):  
Paluanov D.T.
Keyword(s):  
Hydrostatic Pressure ◽  
Strain State ◽  
Soil Base ◽  
Stress Strain ◽  
Stress Strain State ◽  
Low Head ◽  
Calculated Model

This article is considered stress-strain state of low-head dams’ basis on stratified soil. The peculiarities of construction of low-head dams on stratified soils are resulted. The calculated model for the solution of the stress-strain state of low-head dams’ basis is resulted. The calculations of the stress-strain state of soil base under the weight of the constructions and the hydrostatic pressure of water the upstream dam are established.

Sign in / Sign up

Export Citation Format

Share Document