Stress-strain State Of Soil Research Articles

ПРОЕКТИРОВАНИЕ ГРУНТОВЫХ АНКЕРОВ. УЧЕТ ТОРЦЕВОГО СОПРОТИВЛЕНИЯ УШИРЕНИЯ ГРУНТОВОГО АНКЕРА ПРИ РАСЧЕТЕ ЕГО НЕСУЩЕЙ СПОСОБНОСТИ ПО ГРУНТУ.

Currently, ground grouted anchor systems are widespread in geotechnical construction. One of the stages of anchor system designs is ultimate load-holding (bearing) capacity calculation. To date, a clear methodology for calculation the bearing capacity of a ground anchor is not presented by the current regulatory documents. On the other hand, the existing calculation methods for determining the bearing capacity of the anchor (which are presented in SP 381.1325800, VSN 506-88, TSN-50-302-2004 and others) do not take into account all geometric parameters and technological factors. Therefore, the results of determination bearing capacity are significantly lower than the actual ones. Also, the calculation of the bearing capacity is reduced to determination the lateral surface resistance of the anchor’s cylindrical body only. An end-bearing resistance component of the fixed anchor is not taken into account by calculation. This article raises the issue of reliable determination of the ground grouted anchor’s calculated bearing capacity, taking into account all geometric and technological factors, and also considers the stress-strain state of soil and the destruction mechanics.

Influence of pipe jacking excavation in overlying quicksand layer on surface settlement and numerical analysis

The cause of quicksand in soil depends on the nature of soil. Under the action of permeability, quicksand is easy to occur when the pore ratio of soil is large, the water content is large, the clay content is small, the silt content is large, the permeability coefficient is small and the drainage performance is poor. Therefore, quicksand phenomenon is easy to occur in fine sand, silt and loam, but whether quicksand phenomenon occurs or not also depends on certain external conditions, that is, the hydrodynamic pressure (permeability) generated by the seepage of groundwater in the soil. When the upward seepage force of unit granular soil is greater than or equal to its own gravity, the soil will suspend and move. In the process of underground engineering construction, if the problem of quicksand is not solved, the structure will displace with the flow of sand layer, which will change the bearing layer of the foundation and do great harm to the structure. This phenomenon should be eliminated. Practice shows that many accidents of underground structures are related to quicksand caused by the change of seepage conditions during construction. The disturbance of soil in pipe jacking construction is the fundamental cause of soil deformation. It destroys the original natural equilibrium state of soil, changes the stress-strain state of soil, and makes the undisturbed soil experience complex stress paths such as extrusion, shear and deformation. In this paper, a numerical model is established to analyze the surface settlement trend of pipe jacking in quicksand covered stratum, and the methods of grouting behind pipe jacking wall and excavation surface stability measures are verified to control the settlement measures in the construction process.

Stress-Strain State of Soils Under Thin Shell Structures with Infill

Stress-Strain State of Soils Under Thin Shell Structures with Infill

Determination of technological parameters of soil compacting process

The article is devoted to determine the technological parameters of soil compaction by rollers according to soil properties in construction. The compaction of the soil occurs due to certain force loads on the soil. Nowadays, there are enough methods to determine the technological parameters of soil compaction process, however, there are few research methods that consider the system of soil-machine-technological parameters. The urgency of the soil compaction process, which ultimately determines the quality of construction products, was emphasized. The basic physical and mechanical properties of soil and technological parameters of the compaction process were given. Analysis of discrete mathematical model of interaction between roller and soil was carried out in order to determine the technological parameters of soil compaction process in the field of construction technologies. A rheological model to describe the soil properties was used. The differential equations of the interaction between roller and soil have been made. A numerical calculation method to solve the differential equations has been proposed. The basic technological parameters of soil compaction process by rollers have been determined - the thickness of soil layer to be compacted, the number of the roller passes, and the speed of the roller movement. The methodology of theoretical and experimental researches of interaction between roller and soil has been proposed in order to clarify the mathematical model and to find the technological parameters of the compaction process. Experimental research methods are based on the determination of the stress-strain state of soil and on the Fourier analysis of the experimental data. Fourier analysis of the experimental data makes it possible to analyze the qualitative energy spectrum of the interaction between roller and soil to determine the rational amplitude-frequency characteristics of the compaction process. Experimental studies allow obtaining such rheological properties of soil as elasticity, viscosity, coefficient of elastic resistance, etc. The main recommendations for the choice of compaction method depending on the type of soil have been proposed.

EXİSTİNG MODELS OF SOİL RESİSTANCE AND THEİR CONSİDERATİON DURİNG THE OPERATİON OF AN UNDERWATER OİL AND GAS PİPELİNE

Searching for all the parameters of the problem allows you to consider a solution to the contact problem. The purpose of solving the problem is to determine the stress strain state of soils and aggregates, as well as the characteristics of their load capacity.

Проявления акустической эмиссии в мерзлых грунтах при одновременном влиянии на них переменных механических и термических воздействий

The subject of the research is to establish the fundamental laws of acoustic emission in frozen soils, which allow to create ways to control (monitor) their stability under the influence of variable temperature fields and quasistatic mechanical stress from engineering objects located on these grounds for various purposes. The applied importance of such methods is to increase the speed and reduce the complexity of engineering geological surveys in the northern regions of Russia, carried out with the aim of predicting the loss of stability of the bases of buildings and structures to ensure their safe operation. The study was performed on the original instrumental complex. Its description and characteristics are given. With the use of this complex, thermoacoustic emission effects arising from the repeated alternation of freezing and thawing cycles of the soil during the development of its deformed state, starting from the normal compaction phase and up to the final stage of destruction (the bulging phase), have been studied. It is shown that on the basis of such informative parameters as thermally stimulated activity and duration of acoustic emission pulses, an indicator can be obtained that quantitatively characterizes the stages of the stress-strain state of soils. An experimental dependence of the field of values of this indicator as a function of the mechanical stress and the fractional composition of the test soil is given. The qualitative convergence of this dependence with the classical soil deformation diagram obtained by N.M.Hersevanov is shown, where the stages of compaction, loss of stability (shifts) and destruction are highlighted. Possible physical mechanisms and features of the formation of an acoustic emission response at each of these stages are considered and substantiated. It is noted that the approaches to receiving, processing and interpreting acoustic emission measurement information, which are grounded within the framework of the study, allow to control and monitoring of the carrying capacity and stress-strain state of soils directly in the field.

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

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.

Wave processes in determining mechanical characteristics of soils

Mechanical characteristics of soils under dynamic and static loads are determined in laboratory conditions on special devices. Dynamic loads in the devices are initiated by an impact on a soil sample. Under the impact the waves are initiated in soil; they significantly affect the stress-strain state of soil samples placed in the device. Depending on the parameters of the impact load in the device, in different sections of soil sample there arise the stress-strain states, different in quality and quantity. Mechanical characteristics of soil, determined by this stress-strain state, also differ. The effect of stress-strain state of soil on its mechanical characteristics can be estimated theoretically. The initiation of the wave process and dynamic stress-strain state in soil sample placed in the device can be theoretically examined in detail. In this regard, the wave problem is set, which corresponds to the statement of experiments on the device of dynamic loading of soil. The law of soil strain is taken as an elastic-viscoplastic one. Numerical solution of wave equations is obtained by the finite difference method. Based on the analysis of stress-strain state of soil in various sections, obtained by numerical calculations, the condition is derived under which the effect of wave processes on mechanical characteristics of soils is eliminated. This condition (formula) establishes the relationship between the wavelength, the velocity of wave propagation in soil, the thickness of the soil sample in the device and the duration of dynamic load.

Исследование напряженно-деформированного состояния почвогрунта под гусеничной лесной машиной

Исследование напряженно-деформированного состояния почвогрунта под гусеничной лесной машиной

Geomechanical Substantiation of the Parameters of Injection Fixing of the Soil Bases During the Liquidation of the Emergency Condition of the Structure

The emergency condition of a structure that is complex in plan of and located in the mine development zone. As a result of a complex of engineering-geological and geophysical surveys it was established that the cause of significant deformations of the foundations of the structure are the zones of weakened and water-saturated grounds at the base of the foundations, formed due to changes in the hydrogeological regime and man-made accidents. The technique of substantiation of technological parameters of the injection method to soil consolidation is described, including computer modeling, forecasting of deformations of the naturaland fixing massif, analysis of the stress-strain state of soils in the most dangerous area. The effectiveness of the adopted scheme of injecting reinforcement was confirmed according to the approved methodology for liquidation of an emergency condition of a mining structure. It is proposed to create additional fixed zones within the formed zone.

Effect of the Stress-Strain State of Sandy-Clay Soils on Their Thermally Stimulated Acoustic Emission

The thermally stimulated acoustic emission of samples of sandy-clay soils under a mechanical load was studied experimentally. The characteristics of the acoustic emission upon freezing and thawing of soils as a function of their content of clay and sandy particles as well as the magnitude of the load were determined. It was shown that different stages of the stress-strain state of soils can be identified according to the thermally stimulated acoustic emission parameters. A numerical thermo-acousto-emission criterion for evaluating the rupture rate of structural bonds in frozen soils upon their warming and the change of the stress state was developed.

Increasing Stability of Mine Surface Facilities on the Fill-Up Ground

The emergency condition of the mine surface facilities including a coal wash plant, a crusher, a bunker and three galleries, is considered. As a result of a complex of engineering-geological and geophysical surveys, it is established that the significant deformations of the foundations of the structure are caused by the zones of weakened (unconsolidated) soil in the bases of the foundations formed due to landslide developments in the bulk ground mass. The article describes the techniques for justifying the technological parameters of the consolidation grouting of soil bases including computer modeling, forecasting of deformations of the natural and consolidated ground mass, analysis of the stress-strain state of soils in the most dangerous area. The effectiveness of the adopted scheme of consolidation grouting of soil bases according to the approved methodology for elimination of the emergency condition of the mine surface facility was confirmed. The limit values of the calculated horizontal deformations in the soil bases of one of the supports of the galleries are determined. To prevent the indicated deformations, it was recommended to provide an additional row of injection wells with a depth below the border of the loosened soil zone.

Bed – Structure System Analysis for Soil Freezing and Thawing Using the Termoground Program

A description is presented for a mathematical model to determine temperature patterns in structure beds that consider phase transitions in soil moisture, as well as the stress-strain state of soil over the course of freezing and thawing. Analysis examples are considered for various permafrost occurrence conditions and temperature exposures.

Resistance characteristics of soils in the beds of precast piles

Results are presented for experimental studies of the stress-strain state of soils in the beds of precast piles during their installation, and as they receive static loads. Laws governing phenomena that occur in the soils, which define the settlement of the piles and their bearing capacity, are established.

Monitoring of the stress-strain state of soils in the foundation beds of structures

The characteristic features of, and the prospects for geomonitoring in Saint Petersburg are presented.

ANALYSIS OF AXISYMMETRIC BORE-TYPE FOUNDATION IN RESPECT OF PLASTIC DEFORMATION/AŠIAI SIMETRINIO GRĘŽININIO PAMATO ANALIZĖ ĮVERTINANT PLASTINES DEFORMACIJAS

ANALYSIS OF AXISYMMETRIC BORE-TYPE FOUNDATION IN RESPECT OF PLASTIC DEFORMATION/AŠIAI SIMETRINIO GRĘŽININIO PAMATO ANALIZĖ ĮVERTINANT PLASTINES DEFORMACIJAS