scholarly journals Increasing the Accuracy in Determining the Basis Foundation Compressibility

2018 ◽  
Vol 7 (3.2) ◽  
pp. 209
Author(s):  
Nataliia Kostochka ◽  
Iryna Miroshnychenko ◽  
Oleksandr Nalyvayko
Keyword(s):  
Soil Sample ◽  
Prediction Accuracy ◽  
Soil Deformation ◽  
Compression Tests ◽  
Lateral Expansion ◽  
Deformation Parameters ◽  
Compressibility Index ◽  
Porosity Coefficient ◽  
Soil Compressibility ◽  
Relative Change

The disadvantages of the standard soil deformation characteristics are analyzed. Impact of different factors on the determination accuracy of soil characteristics is estimated. Devices to determine soil deformation parameters in the conditions of one axial compression aimed at increase in reliability of the soil compressibility evaluation results are improved; the mentioned improving eliminate disadvantages of the compression device that is absence of the soil sample lateral expansion and friction with ring walls decreasing the soil sample lateral expansion and reduces real soil compressibility. Results of the soil tests in the standard and improving device are compared with each other. Soil compressibility index is based. Such index represents the relative change in the soil sample porosity coefficient during the compression tests. There is increase in prediction accuracy of the building soil foundations settlements. To increase prediction accuracy soil compressibility index and account of the influence of pressure on the soil deformation parameters and soil porosity changing from the compressible thickness depth are used. Statistical analyze of the random variables of the soil base settlements, which are predicted by the both methodic are made.  

scholarly journals Improvement of settlement calculations of building foundations by increasing the reliability of determining soil compressibility indices

2019 ◽  
Vol 1 (52) ◽  
pp. 115-123
Author(s):  
Yuriy Vynnykov ◽  
Muhlis Hajiyev ◽  
Aleksej Aniskin ◽  
Irina Miroshnychenko
Keyword(s):  
Soil Compaction ◽  
Deformation Modulus ◽  
Summation Method ◽  
The Body ◽  
Soil Deformation ◽  
Deformation Parameters ◽  
Complex Approach ◽  
Magnitude Variation ◽  
Soil Compressibility ◽  
Soil Compression

Ways to improve the methods of calculating the foundations bases’ settlements by increasing the reliability of determiningthe soil compressibility indices are substantiated. The complex approach to refinement of the buildings bases' settlements calculationby the layer summation method is investigated by accounting for the soil deformation modulus variability in the fullpressure range perceived by the base at loading; soil strength coefficient βZ; soil deformation anisotropy by elastic orthotropicmodel; tendencies to magnitude variation in the soil deformation modulus in depth of the body under the foundations andwithin the artificial bases built with the soil compaction. There was also proved the possibility of increasing the accuracy ofthe predicting method for the buildings' foundations base settling using the soil compression index and accounting for thepressure effect on the soil deformation parameters in depth of the compressible strata.

scholarly journals EVALUATION OF DISTURBED PARAMETERS OF THE NATURAL STRUCTURE OF THE LABORATORY SAMPLES OF CLAY DEPOSITS DURING ENGINEERING AND GEOLOGICAL SURVEYS IN SAINT-PETERSBURG TERRITORY AND NEAREST AREAS

2018 ◽  
Vol 13 (6) ◽  
pp. 48-65 ◽  
Author(s):  
V. A. Vasenin
Keyword(s):  
Statistical Analysis ◽  
Soil Mechanics ◽  
Natural Structure ◽  
Technical Standards ◽  
Geological Surveys ◽  
Clay Deposits ◽  
Porosity Coefficient ◽  
Relative Change ◽  
And Storage

In Russian technical standards there are no criteria for the natural structure disturbance degree of laboratory samples of coherent dispersed soils. At the same time, such soils are widely represented in various regions of the country, in particular, in St. Petersburg. The paper discusses various criteria for estimating the degree of natural structure disturbance of laboratory samples, and also considers various methods for restoring the strength of samples. The main attention is paid to the evaluation of the degree of violation of the natural structure of laboratory samples when performing odometric tests. The statistical results of such an assessment are given for more than 3,000 oedometer tests of quaternary soils of different genesis based on deformation criteria. The quality assessment of laboratory samples was evaluated at 130 sites performing engineering and geological surveys (by various organizations) in St. Petersburg from 2003 and 2018. According to the results of statistical analysis, it was shown that the quality of samples by the criterion of the relative change in the porosity coefficient at the effective household stress corresponds to "poor" or "very poor" (according to the scale proposed by Т. Lunne and others). The main causes of the violation of the natural structure of the samples (sampling without primers, violation of sampling and storage rules, as well as transportation of samples) are described. Based on the results of a statistical analysis of the deformation parameters of laboratory soil samples during the implementation of complex geological survey in St. Petersburg, it was concluded that it is impossible to use the test results of these samples for performing geotechnical calculations using modern models of soil mechanics without special correction procedures.

Hot Deformation Studies of a Low Carbon Steel Containing V

2013 ◽  
Vol 554-557 ◽  
pp. 1224-1231 ◽  
Author(s):  
Cecilia Poletti ◽  
Martina Dikovits ◽  
Javier Ruete
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Flow Instability ◽  
True Strain ◽  
Low Carbon Steel ◽  
Dynamic Effect ◽  
Rate Sensitivity ◽  
Low Carbon ◽  
Compression Tests ◽  
Deformation Parameters

Low alloyed steels produced by continuous casting are thermomechanically treated to achieve final high mechanical properties, meaning a good combination of strength and toughness. The hot deformation mechanisms of a micro-alloyed steel containing up to 0.1wt% of V is studied by means of hot compression tests using a Gleeble®3800 device. Austenitization of samples is carried out at 1150°C during 2 minutes followed by cooling to the deformation temperature at 1Ks-1in the range of 750 – 1150°C. The studied strain rate range is from 0.01 to 80 s-1and the total true strain achieved is of 0.7. In situ water quenching is applied after the deformation to freeze the microstructure and avoid any post dynamic effect. The Ar3temperature is determined by dilatometry experiments to be 725°C for the used cooling rate. The stress values obtained from the compression tests are evaluated at different strains to determine the strain rate sensitivity and flow instability maps and thus, to predict the formability of the material in the range of studied deformation parameters. These maps are correlated to the microstructure at specific deformation parameters.

Effect of Hot Deformation Parameters on Flow Behavior and Microstructure of Ti-6Al-4V-0.2O Alloy

2017 ◽  
Vol 898 ◽  
pp. 137-143
Author(s):  
Lin Xiang ◽  
Bin Tang ◽  
Hong Chao Kou ◽  
Jie Shao ◽  
Jin Shan Li
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Dynamic Recovery ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Strain Rates ◽  
Compression Tests ◽  
Height Reduction ◽  
Deformation Parameters

Isothermal compression tests were conducted to investigate the effect of hot deformation parameters on flow behavior and microstructure of Ti-6Al-4V-0.2O alloy. The experimental results show that the strain rate and height reduction have little effect on the volume fraction of primary α at a deformation temperature of 860 ̊C. At a deformation temperature of 940 ̊C, the volume fraction of primary α at a high strain rate (10s-1) is about 10% less than that at low strain rates (0.01s-1~1s-1). It may be one of the reasons for the significantly discontinuous yielding phenomenon. Another reason is that the dislocation density decreased suddenly due to the dynamic recovery. With the increasing strain rate and the decreasing deformation temperature, the volume fraction of irregular secondary α increases and lamellar secondary α decreases. And with height reduction increasing, the irregular secondary α increases firstly and then tends to be steady because of dynamic recovery and recrystallization.

On the Indentation Testing of Articular Cartilage: Determination of the Effective Poisson’s Ratio Using Two Different-Sized Punches

2008 ◽  
Author(s):  
Eugene T. Kepich ◽  
Roger C. Haut
Keyword(s):  
Articular Cartilage ◽  
Poisson’S Ratio ◽  
Direct Determination ◽  
Collagen Fibers ◽  
Poisson's Ratio ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Collagen Network ◽  
Lateral Expansion

Effective Poisson’s ratio (EPR) of articular cartilage in compression is an important parameter, which is inversely correlated with stiffness of the collagen fibers [1]; and thus, if known, could provide valuable information about integrity of the collagen network in the tissue. Unfortunately, direct determination of the EPR by measuring lateral expansion during unconfined compression tests [2], while being effective, due to it’s destructive nature many times is not desired and/or hard to apply in practice. Optically-determined values of equilibrium EPR for bovine humeral articular cartilage using this method are reported to be in range 0.185±0.0065.

Experimental investigation on static recrystallization behavior of a low carbon Nb–V–Ti microalloyed steel

2021 ◽  
Vol 118 (2) ◽  
pp. 202
Author(s):  
Fei Li ◽  
Liwen Zhang ◽  
Chi Zhang ◽  
Qing Yang ◽  
Chaoqun Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Deformation Temperature ◽  
Static Recrystallization ◽  
Microalloyed Steel ◽  
Pipeline Steel ◽  
Low Carbon ◽  
Compression Tests ◽  
X70 Pipeline Steel ◽  
Deformation Parameters

The static recrystallization (SRX) behavior of a low carbon Nb–V–Ti microalloyed steel X70 was investigated by two-pass hot compression tests. The compression tests were carried out at deformation temperatures of 1000–1150 °C, strain rates of 0.01–5 s−1, pre-strains of 0.1–0.2 and interval times of 1–50 s. The effects of deformation parameters on SRX behavior were analyzed. The experimental results showed that deformation temperature, pre-strain and strain rate had significant influence on SRX fraction, while initial grain size had a smaller impact. The effects of deformation parameters on SRX microstructure were discussed, and the microstructure evolution process was analyzed. Higher deformation temperature, strain rate and pre-strain lead to larger SRX fraction. The kinetics and recrystallized grain size models for SRX of X70 pipeline steel were developed. Comparison between the predicted results and the experimental ones indicated that the established equations could give a reasonable description for SRX behavior of X70 pipeline steel.

DETERMINATION OF EXPANSIVE SOIL STRENGTH USING A FRACTAL MODEL

Fractals ◽  
2001 ◽  
Vol 09 (01) ◽  
pp. 51-60 ◽  
Author(s):  
YONGFU XU ◽  
DE'AN SUN
Keyword(s):  
Shear Strength ◽  
Soil Sample ◽  
Expansive Soils ◽  
Triaxial Compression ◽  
Expansive Soil ◽  
Fractal Model ◽  
Dry Density ◽  
Compression Tests ◽  
Surface Fractal ◽  
Strength Formula

The micropore surface fractal model for expansive soils is proposed in this paper. Based on the results of the mercury intrusion tests, it is found that the micropore surface fractal dimension is 2.40 for the soil sample with the dry density of 1.50 g/cm 3, and is 2.47 for the soil sample with the dry density of 1.60 g/cm 3. By using the micropore surface fractal model, the shear strength formula for expansive soils is obtained. All the parameters in the proposed shear strength formula are constant, and are independent of matric suction. The validation of the proposed shear strength formula is proven by the results of the triaxial compression tests on an expansive soil taken from Ningxia, China.

scholarly journals Comparison of Proctor and Uniaxial Compression Tests for Selected Soils

2018 ◽  
Vol 22 (1) ◽  
pp. 5-13
Author(s):  
Dariusz Błażejczak ◽  
Kinga Śnieg ◽  
Małgorzata Słowik
Keyword(s):  
Uniaxial Compression ◽  
Compression Test ◽  
Humus Content ◽  
Solid Particles ◽  
Dry Density ◽  
Uniaxial Compression Test ◽  
Compression Tests ◽  
Lateral Expansion ◽  
Soil Material ◽  
Uniaxial Test

AbstractThe objective of this paper was to compare the results of soil material compaction carried out with the use of the Proctor and uniaxial compression tests in order to find relations between these methods. Soil material in the form of loose mass was collected from the layer deposited at the depth from 35 to 60 cm in order to determine its typical properties (textural group, density of solid particles, humus content, reaction, plastic and liquid limits) and in order to compact it in the Proctor apparatus and in the uniaxial compression test. Results of both tests were used for construction of regression models reflecting the course of the unit stress (Pρdp), necessary to generate compaction equal to the dry density of solid particles obtained in the Proctor apparatus (ρdp) in relation to the sample moisture (ws). It was stated that the stress value Pρdp on the soil sample in the uniaxial compression test depends significantly on ws. It was proved that for the purpose of comparing the results of both tests, the uniaxial stress of samples must be performed in conditions of their lateral expansion. It was also proved that the use of the uniaxial test with possible lateral expansion of soil with a model sample, a diameter of which is 100 and the height is 30 mm, one may determine the obtained compaction with the use of the plate movement value.

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.

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