scholarly journals INFLUENCE OF CLAYEY SOIL STRUCTURE ON ITS MODULUS OF STIFFNESS

1999 ◽  
Vol 5 (2) ◽  
pp. 108-115
Author(s):  
Antanas Alikonis
Keyword(s):  
Soil Structure ◽  
Clayey Soil ◽  
Deformation Modulus ◽  
Natural Soil ◽  
Logarithmic Scale ◽  
Compression Curve ◽  
Engineering Structures ◽  
Compacted Soil ◽  
Deformation Properties ◽  
Compressibility Coefficient

Disturbance of soil structure influences its density, strength and deformation properties. Among other cases soil structure could be disturbed by compacting it. It is possible to increase deformation properties of sand or gravel by compacting them. However, for clay soils deformation properties may increase if they are compacted. Differences of settlements of a building depends on the different deformation properties of the artificially placed and compacted soils beneath the foundations. Different values of stiffness modulus are used for the structural design of the buildings which are constructed on the soils with different compressibility. Coefficient of changeability of soil compression (1) was used. It may be calculated as a ratio of maximum and minimum values of deformation modulus, or according to the maximum and minimum values of coefficient of relative compressibility (3). Coefficient of the relative compressibility of soil can be calculated depending on the maximum and minimum values of tip resistence from CPT test (5). According to the coefficient of the relative compressibility we could estimate whether the soil is uniform, nonuniform or extremely non-uniform. It is important for the design of civil engineering structures. Mechanical properties of soils may be back-calculated using theoretical values of settlements and loads. Most frequently within the building layout area soils are natural and artificially compacted. For a compacted soil it is possible to draw compression curve in semi-logarithmic scale using compression curve of the same natural soil and the void ratio of the artificially placed and compacted soil. Thus we can determine compressibility of the soil with disturbed or undisturbed structure. Using parameters of soil compressibility, we can determine the coefficient of the relative compressibility, maximum and minimum values of settlement and modulus of stiffness.

scholarly journals INFLUENCE OF CHANGE OF COMPACTED SAND STRUCTURE ON THE DESIGN STRENGTH OF SUBSOIL

1998 ◽  
Vol 4 (4) ◽  
pp. 283-291
Author(s):  
Antanas Alikonis
Keyword(s):  
Bearing Capacity ◽  
Void Ratio ◽  
Deformation Modulus ◽  
Physical And Mechanical Properties ◽  
Natural Soil ◽  
Cylindrical Shape ◽  
Foundation Design ◽  
Design Strength ◽  
Compacted Soil ◽  
Tip Resistance

The values of deformation modulus and strength properties of subsoil increases during compaction. The increase depends on the content, grading of the soil, mechanical influence on the soil and other properties. The influenced space with changed soil properties may be formed by tamping the pits for the foundation. It is very important by using physical and mechanical properties of natural soil to forecast the density of compacted soil. For this purpose we have to determine the maximum density value of dry soil and calculate the void ratio of the compacted soil. Change of sand soil density is low. Thus its mean value is commonly used in engineering calculations. The tip resistance CPT of sand can be calculated according to correlation between tip resistance CPT and void ratio (7), (8). When tip resistance CPT is obtained, it is possible to calculate the bearing capacity of the compacted subsoil and to design the foundation. The assumption is made, that the design bearing capacity of foundation installed in the tampered pits is equal to the stresses in the subsoil when the settlement of the foundation is equal to 1…3% of the foundation diameter. According to the tests, the correlation between tip resistance CPT and the bearing capacity of subsoil was made. It should be pointed out that the design bearing capacity of the foundations in the tampered pits are different depending on the shape of foundation. Design bearing capacity of the pyramidal foundations according to the tests results: R sn = 0,04nq c . Design bearing capacity of the cylindrical foundations according to the tests results: R sn = 0,16nq c . It is obvious that bearing capacity of the cylindrical shape foundation installed in tampered pits of sandy soil is bigger than the pyramidal one. The reason is that the main part of the bearing capacity of pyramidal shape foundation is realised by the foundation side bearing capacity. The foundation side bearing capacity of the cylindrical shape foundation is smaller. Design bearing capacity of the foundation in tampered pits may be calculated according to the equations (15), (16), (18). The value of the bearing capacity of the sandy subsoil may be increased up to five times by tampering the pits.

scholarly journals Geotechnical Evaluation of Diesel Contaminated Clayey Soil

2021 ◽  
Vol 11 (14) ◽  
pp. 6451
Author(s):  
Christian E. Hernández-Mendoza ◽  
Pamela García Ramírez ◽  
Omar Chávez Alegría
Keyword(s):  
Contaminated Soils ◽  
Clayey Soil ◽  
Friction Angle ◽  
Geotechnical Properties ◽  
Natural Soil ◽  
Osmotic Suction ◽  
The One ◽  
Available Information ◽  
The Impact ◽  
Diesel Contamination

Soil contamination by different hydrocarbons has rapidly expanded worldwide, surpassing the self-purification capacity of soils and increasing the number of contaminated sites. Although much effort has been devoted to study the effects of diesel contamination on the geotechnical properties of soil, there is still limited available information about it. Moreover, there is no available information about the maximum diesel retention that soil can have and its effect on the geotechnical behavior of the soil. Thus, in this paper, we determined the maximum diesel retention by an unsaturated clayey soil and evaluated the impact of diesel contamination on its geotechnical properties. The results showed that the soil could only retain 12.6% of the added diesel and the excess was expulsed. At such a diesel concentration, the saturation rate of the soil was lower than 80%. Diesel contamination increased the plasticity and the internal friction angle of the soil, while its cohesion was considerably decreased. It should be noted that the matric suction of contaminated soil was lower than the one obtained for natural soil. However, its osmotic suction was considerably higher. This indicates that osmotic suction must be considered to evaluate the shear strength of contaminated soils.

scholarly journals Deformation of rockfill in bodies of rockfill dams

2019 ◽  
pp. 5-5
Author(s):  
Mikhail Sainov
Keyword(s):  
Reinforced Concrete ◽  
Deformation Modulus ◽  
Deformation Model ◽  
Observation Data ◽  
Linear Deformation ◽  
Laboratory Test Results ◽  
Wide Range ◽  
Deformation Properties ◽  
Non Linear ◽  
The Impact

Introduction. The main factor determining the stress-strain state (SSS) of rockfill dam with reinforced concrete faces is deformability of the dam body material, mostly rockfill. However, the deformation properties of rockfill have not been sufficiently studied yet for the time being due to technical complexity of the matter, Materials and methods. To determine the deformation parameters of rockfill, scientific and technical information on the results of rockfill laboratory tests in stabilometers were collected and analyzed, as well as field data on deformations in the existing rockfill dams. After that, the values of rockfill linear deformation modulus obtained in the laboratory and in the field were compared. The laboratory test results were processed and analyzed to determine the parameters of the non-linear rockfill deformation model. Results. Analyses of the field observation data demonstrates that the deformation of the rockfill in the existing dams varies in a wide range: its linear deformation modulus may vary from 30 to 500 МPа. It was found out that the results of the most rockfill tests conducted in the laboratory, as a rule, approximately correspond to the lower limit of the rockfill deformation modulus variation range in the bodies of the existing dams. This can be explained by the discrepancy in density and particle sizes of model and natural soils. Only recently, results of rockfill experimental tests were obtained which were comparable with the results of the field measurements. They demonstrate that depending on the stress state the rockfill linear deformation modulus may reach 700 МPа. The processing of the results of those experiments made it possible to determine the parameters on the non-linear model describing the deformation of rockfill in the dam body. Conclusions. The obtained data allows for enhancement of the validity of rockfill dams SSS analyses, as well as for studying of the impact of the non-linear character of the rockfill deformation on the SSS of reinforced concrete faces of rockfill dams.

scholarly journals DEFORMATION MECHANISM OF STRUCTURAL BODY COMPRESSION

2018 ◽  
Vol 17 (1) ◽  
pp. 29-41
Author(s):  
О. N. Protasenya ◽  
L. V. Larchenkov ◽  
M. L. Protasenya
Keyword(s):  
Deformation Mechanism ◽  
Nuclear Physics ◽  
Soil Structure ◽  
Integrated Approach ◽  
The Other ◽  
Soil Tillage ◽  
Cultivated Plants ◽  
Technical Equipment ◽  
Soil Physics ◽  
Engineering Structures

In order to prepare soil for sowing of agricultural crops it is necessary to have a number of engineering structures that ensure its qualitative treatment and protection from erosion. Modern equipment do not fully meet the whole complex of specified requirements. Application of tillage machinery being used for main soil cultivation is directed on suppression (destruction) of natural vegetation which is considered as the strongest competitor to cultivated plants. From the other side, vegetation on the Earth’s surface plays an important role for reliable protection of soil from erosion. Destruction of vegetation throughout the whole period of crop tending leads to the fact that the remaining cultivated plants are not able to protect soil from erosion by such natural aggressive factors as rain storms and strong winds. As a consequence, processes of soil structure destruction and losses of entire soil strata and its fertility occur in the geographical (landscape) envelope. Thus, equipment for primary and secondary soil tillage exerts double impact: from one side, killing of weeds takes place, and on the other hand, there is destruction (erosion) of soil structure and profiles of its geographical envelope. The soil, in the understanding of the earth, is the perfect place that gives life to plants and organisms, has a fertility. For the last 50 years analytical scope of physical processes occurring in the soil has been extended, physical methods for investigation of soil properties and application of technical equipment for assessment of physical-mechanical soil characteristics have got widespread use. However, there is no summative investigation on soil physics which includes and reveals thermodynamics, electrophysics and nuclear physics of soils. At the same time an integrated approach for studying such complicated object makes it possible to understand important nature of some processes occurring in the soil and to develop practical measures for fertility improvement and erosion reduction. The paper considers problems pertaining to deformation mechanism while forming soil structure and its compression under influence of external loadings: magnetic, electric, physico-chemical, gravitational and thermal fields and working organs of tillage tools.

scholarly journals Laboratory Plate Loading Test on Calcareous Sands from a Hydraulic fill Reef Island

2021 ◽  
Author(s):  
Xing Wang ◽  
YANG WU ◽  
Jie Cui ◽  
Chang-qi Zhu ◽  
Xin-zhi Wang
Keyword(s):  
Bearing Capacity ◽  
Deformation Modulus ◽  
Fine Sand ◽  
Medium Sand ◽  
Calcareous Sand ◽  
Loading Test ◽  
Moisture Condition ◽  
Hydraulic Fill ◽  
Deformation Properties ◽  
Plate Loading

Abstract The landforms and vertical strata distribution characteristics of Yongxing Island show that the reclaimed reef island is characterized by soft upper strata (calcareous sand) and hard lower strata (reef limestone). In this study, a series of plate loading tests was conducted to examine the influences of particle gradation, compactness, and moisture condition on the bearing mechanism and deformation properties of the calcareous sand foundation. When the foundation is shallowly buried, the relative density range corresponding to a calcareous sand foundation exhibiting local shear failure is narrower than that of a terrigenous sand foundation. For the same compactness, dry calcareous medium sand has a much larger bearing capacity and deformation modulus than dry calcareous fine sand. The effect of water on the bearing capacity of the calcareous medium sand is greater than the effect on calcareous fine sand. Its weak cementation and low permeability make the initial deformation of saturated calcareous fine sand slightly smaller than that under dry conditions. The stress dispersion angle of the calcareous medium sand foundation is 52°, which is larger than that of terrigenous sand. A larger stress dispersion angle leads to a higher bearing capacity and deformation modulus than those of terrigenous sand.

Influence of a localized plastic layer on embankment stability

1977 ◽  
Vol 14 (4) ◽  
pp. 524-530 ◽  
Author(s):  
C. D. Thompson ◽  
J. J. Emery
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Clayey Soil ◽  
Plastic Material ◽  
Plastic Layer ◽  
Natural Soil ◽  
General Terms ◽  
Clayey Silt ◽  
The Stability ◽  
Embankment Stability

Conventional stability analyses of a 47 ft (14.3 m) high embankment constructed of clayey silt fill indicated a satisfactory design with 2:1 slopes. However, cracking of the fill and movements of the embankment occurred when its height reached 32 ft (9.8 m). Investigation revealed that, in general terms, the geotechnical profile employed for the stability analysis was satisfactory. There was a localized layer of firm clayey soil at the interface between the fill and natural soil, which coincided with the observed cracks and the zone of high pore pressure.Construction scheduling was critical, and an initial wedge analysis showed that a 17 ft (5.2 m) high berm would ensure adequate safety during completion of the fill. A detailed investigation followed to determine the actual deformation mechanism responsible for the cracking. This included plane strain finite element runs using estimated moduli values. It was concluded that the cracking was caused by ‘spreading’ of plastic material at or near the base of the embankment. This case history illustrates that localized layers of weaker soil can be critical even when construction has been carefully controlled.

e-p curve-based structural parameter for assessing clayey soil structure disturbance

2020 ◽  
Vol 79 (8) ◽  
pp. 4387-4398 ◽  
Author(s):  
Fanyan Meng ◽  
Renpeng Chen ◽  
Xin Kang ◽  
Zhongchao Li
Keyword(s):  
Soil Structure ◽  
Clayey Soil ◽  
Structural Parameter

scholarly journals Physical properties of soils under intensive agricultural management

2005 ◽  
Vol 62 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Jorge Luís Nascimento Soares ◽  
Carlos Roberto Espindola ◽  
Walcylene Lacerda Matos Pereira
Keyword(s):  
Soil Structure ◽  
Sequence Variation ◽  
Soil Bulk Density ◽  
Saccharum Officinarum ◽  
Management Systems ◽  
Vertical Profiles ◽  
Compacted Soil ◽  
Physical Attributes ◽  
Lower Slope

Pedologic alterations after long-term sugar cane (Saccharum officinarum) cropping cycles under traditional soil management systems were studied on a farm in Bariri, SP, Brazil. A toposequence was established to evaluate the effects of the soil position in the relief in changing soil physical attributes. Morphological field descriptions and laboratory analyses were carried out on vertical profiles of the upper, middle and lower thirds of a Typic Haplorthox slope. Soil bulk density and macroporosity changed along the toposequence reflecting on soil hydrodynamics, especially in the lower slope parts. At sites with high clay levels, empty spaces were filled forming block shaped structures together with the micro-aggregate structure. The intensive cultivation induced the greatest soil structure alterations, even at the deepest layers. The study pointed out the importance of performing detailed morphological observations in vertical profiles, due to the great variation on pedological attributes over short distances. Compacted soil sections were observed side-by-side with desaggregated mottles in the same soil profile. This fact evidenced that both vertical (in each profile) and horizontal gradients (along a toposequence) need to be considered in studies of time sequence variation of pedological parameters.

scholarly journals Complex approach to transport infrastructure of Arctic region calculations

2019 ◽  
Vol 265 ◽  
pp. 04002
Author(s):  
Vladimir Ulitsky ◽  
Elena Gorodnova
Keyword(s):  
Numerical Calculation ◽  
Soil Structure ◽  
Research Work ◽  
Arctic Region ◽  
Transport Infrastructure ◽  
Natural Soil ◽  
Northern Sea Route ◽  
Complex Approach ◽  
Permafrost Soils ◽  
Liquefied Gas

At present experts of «Base and Foundation» department of St. Petersburg Transport University do research work and design projects for transport infrastructure objects. Numerical calculation of subsoil in northern ports of Sabbeta and Tanalau settlements in Russian Arctic region is one of these successfully fulfilled projects. Specific features of these ports are the following: to construct building foundations and road embankments on permafrost soils, to predict functioning of compound sea berths and river piers when super heavy arctic vessels transport liquefied gas along the Northern sea route. Numerical calculation allowed defining soil thawing zone under the northern ports’ structures. Experience of experts permitted to choose the best solutions to preserve natural soil structure and exclude uneven deformations, which destroy objects and complicate roads functioning in permafrost zone.

Temperature effects on strength and deformation behaviour of rocks in Southern Ontario

1982 ◽  
Vol 19 (3) ◽  
pp. 307-319 ◽  
Author(s):  
Raymond S. C. Wai ◽  
K. Y. Lo
Keyword(s):  
Deformation Behaviour ◽  
Deformation Modulus ◽  
Temperature History ◽  
Granitic Gneiss ◽  
Experimental Procedure ◽  
Deformation Properties ◽  
History Of ◽  
Strength And Deformation ◽  
Effects Of Temperature ◽  
Increasing Temperature

A laboratory program to study the effects of temperature up to 350 °C on the strength and deformation properties of rocks was carried out. Particular attention was paid to the experimental procedure to avoid premature thermal cracking of the specimens. It was shown that the thermal–mechanical behaviour varies with the rock type. For granitic gneiss, the deformation modulus increases slightly with temperature up to 120 °C, then decreases at a rate of about 25% per 100 °C. Poisson's ratio generally decreases with increasing temperature up to 250 °C. The uniaxial compressive strength of granitic gneiss decreases with increasing temperature at a rate of the order of 30 MPa per 100 °C. The deformation properties of the granitic gneiss are also dependent on the temperature history of the specimen.In contrast, both the deformation and strength behaviour of the limestone appear to be insensitive to temperature change.

Sign in / Sign up

Export Citation Format

Share Document