Development of new tables of transition factors from the results of compression tests to the plate-bearing modulus

2019 ◽  
Vol 13 (1) ◽  
pp. 18-30
Author(s):  
A. N. Trufanov
Keyword(s):  
Effective Stress ◽  
Linear Equations ◽  
Deformation Modulus ◽  
Compression Modulus ◽  
Anomalous Behavior ◽  
Compression Tests ◽  
Starting Point ◽  
Porosity Coefficient ◽  
Modulus Of Deformation ◽  
Soil Flow

The article is devoted to the issue of developing new tables of transition factors relating the results of compression and plate-bearing tests. As is known, the normative value of the modulus of deformation is directly determined from the most reliable plate-bearing tests. However, they are quite laborious and expensive. In contrast to plate bearing tests, compression tests are much cheaper, but they give underestimated values of the deformation modulus. In this connection, a table of transition coefficients from a compression module to a plate-bearing deformation modulus was developed (Agishev – Ignatova table). The article shows that the initial stress ranges selected for the determination of the compression and platebearing deformation modulus differ significantly. The compression module, as well as the odometric modulus of deformation in the latest version of the table, was determined in a fixed pressure range, and the plate-bearing test curve for the linear section, the starting point of which is an alternating natural effective stress. To eliminate this contradiction, when developing new tables, instead of a compression modulus, a tangential odometric modulus of deformation was used, determined for the corresponding value of the natural effective stress. The algorithm for determining new transition coefficients is described in detail. In the new tables, in addition to the porosity coefficient, the soil flow rate is also taken into account. The effect of consistency on the definition of the plate-bearing modulus and the absence of such an effect on the results of compression tests are noted. Anomalous behavior of clay of solid consistency is shown during compression tests. In addition to the tables of transition coefficients, a table of linear equations is provided for a direct transition from the results of compression tests to a plate-bearing deformation modulus. New tables are proposed to be used to determine the standard value of the modulus of soil deformation at the stage of preliminary calculations for the foundations of buildings and structures of the II and III geotechnical categories.

scholarly journals Filter leaching of salt soils of automobile roads

2021 ◽  
Vol 264 ◽  
pp. 02032
Author(s):  
Rashidbek Hudaykulov ◽  
Dilfuza Makhmudova ◽  
Dilshod Kayumov ◽  
Olmos Zafarov
Keyword(s):  
Water Saturation ◽  
General Scheme ◽  
Salt Content ◽  
Deformation Modulus ◽  
Sharp Change ◽  
Study Results ◽  
Salt Crystals ◽  
Porosity Coefficient ◽  
Modulus Of Deformation ◽  
Water Saturated

Globally, in arid regions, due to the irrational use of water resources for irrigating plants, salinization of soils occurs, which causes significant damage to the country's economy. In particular, recently in some regions of Uzbekistan, there has been a rise in groundwater and flooding of territories. In these areas, where the soil bases of highways contain such readily soluble salts as: NaCL, Na2SO4·10H2O, MgSO4·7H2O, MgCL2·6H2O, CaCL2·6H2O, NaHCO3, Na2CO3·10H2O, CaCO3 and CaSO4·2H2O, additional suffusion precipitation is often observed which lead to deformations of road surfaces. Additional precipitation is due to the dissolution of salt crystals upon ingress of moisture during filtration leaching. Filtration leaching of soils was carried out in the F-1M device according to the upward flow pattern. To determine the amount of leached salts during the experiment, the infiltrate was taken, its volume and mineralization were recorded. At the end of the tests, the soil was tested according to the general scheme. To assess the influence of the leaching process on the strength indices of the studied soils by the methods of consolidated and fast shear, tests of pre-leached samples were performed. When testing soils, samples were cut, pre-compacted with the same specified load, and leached for a month. In laboratory conditions, the deformation modulus was determined by performing compression experiments. In connection with a sharp change in the modulus of deformation of soils during moistening, the tests were carried out at two values of humidity: at natural and after water saturation without the possibility of swelling. The study results show that the deformation modulus of water-saturated loams satisfactorily correlates with the value of the initial porosity coefficient and decreases as a result of water saturation and leaching. The degree of decrease depends on the value of the initial deformation modulus: the higher it is, the more significant its change. The value of the coefficient of weakening of the soil structure depends on the effective average pressure. The criterion for the permissible salt content in the base of the roadbed of highways should be taken not only the value of the degree of salinity but also the change in the indicators of the mechanical properties of soils used in the design of the construction of the roadway during soaking and leaching.

Deformation of Porous, Nanostructured Silver at Room Temperature and 150 °C

2013 ◽  
Vol 1513 ◽  
Author(s):  
Guillaume Noiseau ◽  
Michael F. Becker ◽  
John W. Keto ◽  
Desiderio Kovar
Keyword(s):  
Room Temperature ◽  
Local Strain ◽  
Direct Write ◽  
Compression Tests ◽  
Sufficient Energy ◽  
Starting Point ◽  
Mean Size ◽  
Constant Displacement ◽  
Patterned Films ◽  
Porous Silver

ABSTRACTPorous, nanostructured silver samples were produced using a direct-write method where a nanoparticle aerosol consisting of particles with a mean size of approximately 5 nm were accelerated to speeds of approximately 1000 m/sec and impacted onto a translating substrate [1]. The impacting particles have sufficient energy to stick to the substrate, allowing patterned thick films to be directly written from the aerosol without a mask. Unlike other low temperature processing routes for achieving patterned films, no organics are added that can interfere with postdeposition processing. Typical films are 5- 100 μm thick, up to several centimeters long, and have an as-deposited relative densities as high as 70% of bulk Ag. Compression tests were carried out in steps at room temperature and at 150°C under constant displacement rates. Local strain and densification were measured by optical profilometry between each compression step. The results can be used as a starting point to better understand the mechanisms that govern plasticity, creep, and sintering in nanostructured, porous silver at low processing temperatures.

scholarly journals Compression Characteristics of Solid Wastes as Backfill Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Meng Li ◽  
Jixiong Zhang ◽  
Rui Gao
Keyword(s):  
Large Diameter ◽  
Testing Machine ◽  
Deformation Modulus ◽  
Compression Tests ◽  
Initial Portion ◽  
Filling Materials ◽  
Backfill Materials ◽  
Material Testing Machine ◽  
Compression Characteristics ◽  
The Relationship

A self-made large-diameter compression steel chamber and a SANS material testing machine were chosen to perform a series of compression tests in order to fully understand the compression characteristics of differently graded filling gangue samples. The relationship between the stress-deformation modulus and stress-compression degree was analyzed comparatively. The results showed that, during compression, the deformation modulus of gangue grew linearly with stress, the overall relationship between stress and compression degree was approximately nonlinear, and the deformation of gangue was rather large during the initial portion of the test. Gangue sample mixed with Talbot Formula provides the best deformation resistance capacity, followed by fully graded and single-graded gangue samples. For applications, with adjustment of the gradation of filling materials and optimal design of compacting equipment, surface subsidence may be better controlled.

scholarly journals Calculation of a beam on an inhomogeneous basis

2018 ◽  
Vol 251 ◽  
pp. 04023
Author(s):  
Nikolaj Atarov
Keyword(s):  
Numerical Calculation ◽  
Power Law ◽  
Modulus Of Elasticity ◽  
Strain Energy ◽  
Deformation Modulus ◽  
Bending Moment ◽  
System Of Differential Equations ◽  
Total Potential ◽  
Modulus Of Deformation ◽  
Symmetric Load

The questions of analytical calculating the beam on the base with the modulus of deformation (modulus of elasticity), which is changed by thickness of the layer by power law, was deals in the article. The purpose of work was receiving finite expressions for reactive pressure of the basе on a beam and internal efforts in a beam when using model of the base with two characteristics (coefficient of subgrade resistance). A system of differential equations second-order with respect to the displacements of points the surface of a layer with a continuously changing modulus of elasticity was obtained based on the minimum of the total potential strain energy. The calculation of the rigid beam on the base on the action of the symmetric load was performed and the formulas for the reactive pressures of the base were got. Numerical calculation is executed and the analysis of influence of change of the module of deformation of a layer by the amount of reactive pressure and the bending moment in a beam was given. It is shown that with increase in the module of deformation on layer thickness the basе with two characteristics on nature of work is approaching vinklerovsky.

scholarly journals Krylov Subspace Solvers and Preconditioners

2018 ◽  
Vol 63 ◽  
pp. 1-43
Author(s):  
C. Vuik
Keyword(s):  
Iterative Methods ◽  
Krylov Subspace ◽  
State Of The Art ◽  
Linear Equations ◽  
Iterative Solution ◽  
Krylov Subspace Methods ◽  
Numerical Linear Algebra ◽  
Subspace Methods ◽  
Starting Point ◽  
Lecture Notes

In these lecture notes an introduction to Krylov subspace solvers and preconditioners is presented. After a discretization of partial differential equations large, sparse systems of linear equations have to be solved. Fast solution of these systems is very urgent nowadays. The size of the problems can be 1013 unknowns and 1013 equations. Iterative solution methods are the methods of choice for these large linear systems. We start with a short introduction of Basic Iterative Methods. Thereafter preconditioned Krylov subspace methods, which are state of the art, are describeed. A distinction is made between various classes of matrices. At the end of the lecture notes many references are given to state of the art Scientific Computing methods. Here, we will discuss a number of books which are nice to use for an overview of background material. First of all the books of Golub and Van Loan [19] and Horn and Johnson [26] are classical works on all aspects of numerical linear algebra. These books also contain most of the material, which is used for direct solvers. Varga [50] is a good starting point to study the theory of basic iterative methods. Krylov subspace methods and multigrid are discussed in Saad [38] and Trottenberg, Oosterlee and Schüller [42]. Other books on Krylov subspace methods are [1, 6, 21, 34, 39].

On the application of phase relationships to complex structures. XVI. A random approach to structure determination

1978 ◽  
Vol 34 (6) ◽  
pp. 883-892 ◽  
Author(s):  
R. Baggio ◽  
M. M. Woolfson ◽  
J. P. Declercq ◽  
G. Germain
Keyword(s):  
Complex Structure ◽  
Linear Equations ◽  
Phase Development ◽  
Starting Point ◽  
Good Starting Point ◽  
Refinement Process ◽  
Self Consistency ◽  
Random Approach ◽  
Better Than ◽  
Phase Relationships

With triple-phase relationships treated as linear equations it is possible to refine a set of phases from given initial values. Phases so obtained are better than those found by refining to self-consistency with the tangent formula. An investigation of the radius of convergence of the least-squares refinement process showed that a substantially correct solution may often be found even starting with random phases. Systems containing up to 300 phases have been investigated and the results and their implications are discussed. It is concluded that the random approach can, at the very least, be used to obtain 70--100 phases as a good starting point for phase development. There is also the possibility of obtaining a sufficient number of phases directly to define a reasonably complex structure, especially with a computer augmented by an array processor. A problem which can arise with linear equations, as with the tangent formula, is that the phases obtained do not adequately define the enantiomorph and give an E map with a pseudo centre of symmetry. Two methods of overcoming this problem are described.

Anisotropic shear strength of a residual soil of sandstone

2008 ◽  
Vol 45 (3) ◽  
pp. 367-376 ◽  
Author(s):  
Adriano Virgilio Damiani Bica ◽  
Luiz Antônio Bressani ◽  
Diego Vendramin ◽  
Flávia Burmeister Martins ◽  
Pedro Miguel Vaz Ferreira ◽  
...  
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Yield Surface ◽  
Triaxial Compression ◽  
Strength Properties ◽  
Triaxial Tests ◽  
Residual Soil ◽  
Compression Tests ◽  
Soil Stiffness ◽  
Particle Bonding

This paper discusses results of laboratory tests carried out with a residual soil originated from the weathering of eolian sandstone from southern Brazil. Parent rock features, like microfabric and particle bonding, are remarkably well preserved within this residual soil. Stiffness and shear strength properties were evaluated with consolidated drained (CID) and consolidated undrained (CIU) triaxial compression tests. Undisturbed specimens were tested with two different orientations between the specimen axis and bedding surfaces (i.e., parallel (δ = 0°) or perpendicular (δ = 90°)) to investigate the effect of anisotropy. When CID triaxial tests were performed with δ = 0°, the yield surface associated with the structure was much larger than when tests were performed with δ = 90°. Coincidently, CIU tests with δ = 0° showed peak shear strengths much greater than for δ = 90° at comparable test conditions. Once the peak shear strength was surpassed, CIU tests followed collapse-type effective stress paths not shown by corresponding tests with remolded specimens. A near coincidence was observed between the yield surface determined with CID tests and the envelope of collapse-type effective stress paths for δ = 0° and δ = 90°.

3D marine magnetotelluric modeling and inversion with the finite-difference time-domain method

Geophysics ◽  
2014 ◽  
Vol 79 (6) ◽  
pp. E269-E286 ◽  
Author(s):  
Sébastien de la Kethulle de Ryhove ◽  
Rune Mittet
Keyword(s):  
Finite Difference ◽  
Frequency Domain ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Linear Equations ◽  
Time Domain Method ◽  
Domain Method ◽  
Frequency Domain Methods ◽  
Starting Point ◽  
Difference Time

Frequency-domain methods, which are typically applied to 3D magnetotelluric (MT) modeling, require solving a system of linear equations for every frequency of interest. This is memory and computationally intensive. We developed a finite-difference time-domain algorithm to perform 3D MT modeling in a marine environment in which Maxwell’s equations are solved in a so-called fictitious-wave domain. Boundary conditions are efficiently treated via convolutional perfectly matched layers, for which we evaluated optimized parameter values obtained by testing over a large number of models. In comparison to the typically applied frequency-domain methods, two advantages of the finite-difference time-domain method are (1) that it is an explicit, low-memory method that entirely avoids the solution of systems of linear equations and (2) that it allows the computation of the electromagnetic field unknowns at all frequencies of interest in a single simulation. We derive a design criterion for vertical node spacing in a nonuniform grid using dispersion analysis as a starting point. Modeling results obtained using our finite-difference time-domain algorithm are compared with results obtained using an integral equation method. The agreement was found to be very good. We also discuss a real data inversion example in which MT modeling was done with our algorithm.

scholarly journals Experimental Research on Deformation Characteristics of Waste-Rock Material in Underground Backfill Mining

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 102 ◽  
Author(s):  
Pengfei Zhang ◽  
Yubao Zhang ◽  
Tongbin Zhao ◽  
Yunliang Tan ◽  
Fenghai Yu
Keyword(s):  
Field Test ◽  
Axial Strain ◽  
Deformation Modulus ◽  
Rock Material ◽  
Waste Rock ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Slow Increase ◽  
Steel Cylinder ◽  
Backfill Mining

Waste-rock material used in underground backfill mining has a granular texture and acquires non-linear deformation characteristics when compressed. The deformation modulus of waste-rock measured by a laboratory compression test is significantly different from the true deformation modulus in the field, due to the complete confining effect of the loading steel cylinder. In this study, we performed a series of laboratory-based compression tests on waste-rock samples. The results showed that lab-acquired deformation modulus variations of waste rock could be divided into three stages: slow increase, accelerated increase, and rapid increase. We also measured the true deformation modulus of backfill waste rock by conducting a field test in gob areas of the Tangshan coal mine, China. The hardening process of backfill waste rock during the field test was analyzed, and could be divided into four stages: roof contact, rapid compression, slow compression, and long-term stable. With the increase of axial strain, the lab- and field-measured deformation moduli of waste rock both increased exponentially. A correction parameter was proposed to investigate the relationship between the field-generated true deformation modulus and the lab-tested deformation modulus. The correction parameter k positively correlated with the axial strain, in the form of an exponential function. The magnitude of k was between 0.5616 and 0.6531.

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