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卷 54, 编号 2 (2017)
- 年: 2017
- 文章: 12
- URL: https://journals.rcsi.science/0038-0741/issue/view/15193
Soil Mechanics
Analysis of Strip Pile Footing Behavior Caused by Sinkhole Formation
摘要
The paper presents the results of investigation of pile strip footing behavior over a karst sinkhole. Analytical decisions based on the adapted contact model of pile-subsoil interaction were obtained to evaluate the pile stiffness coefficient and maximal loads acting on the piles.
71-75
Geometrically Nonlinear Buckling Stability Analysis of Axially Loaded Underground Pipelines
摘要
The paper presents an analysis of buckling stability of underground engineering life-support systems, located in water-saturated soils. Analytical and numerical(FEM) solutions are presented and shown to agree well. The influence of soil rheological properties, as well as pipeline geometrical and mechanical parameters on the system dynamic stability, was numerically simulated.
76-80
Effect of the Stress-Strain State of Sandy-Clay Soils on Their Thermally Stimulated Acoustic Emission
摘要
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.
81-86
Settlement of Soft Clay Subgrade Under Coupled Effects of Vibration Frequency and Dynamic Stress Ratio Caused by High-Speed Train Loads
摘要
Settlement regularity of soft clay subgrade under cyclic principal stress rotation caused by high-speed train loads is investigated. In laboratory tests, it is found that, with increasing vibration frequency at a fixed dynamic stress ratio, the increase of axial plastic cumulative strain in saturated soil is restricted at mid-high frequencies (0.5-2 Hz), and the changes in pore-water pressure are not evident. Combined with the empirical settlement formula and analysis of the dynamic amplification equation of German standard, a simplified settlement calculation method accounting for resonance is obtained.
87-96
Experimental Investigations
Increased Bearing Capacity of Piles Driven In Clay
摘要
This paper investigates the increase in bearing capacity of a pile immersed in clay soils. It is shown for nonsaturated soils that such growth is mainly caused by capillary shrinkage during pile driving, followed by expansion of soils exposed to atmospheric humidity. For the case of saturated soils, the increase in piles bearing capacity can be explained by the influence of an air-gas component occurring with instantaneous soil compaction caused by filtration of highly viscous gas-saturated water under the conditions of a "closed system." New reliable methods for evaluation of the change in pile bearing capacity with time were developed.
97-101
Laboratory Investigation of Deformation and Strength Characteristics of Saline Frozen Silty Sand
摘要
A series of triaxial compressive strength tests was conducted to investigate the effect of Na 2 SO 4 and confining pressure on the deformation and strength characteristics of frozen silty sand at 6°C. The initial elastic modulus increased with increases in the salt content, whereas the confining pressure had only a slight effect. An increase in the confining pressure resulted in an increase in strength. The results illustrated that the cohesion of the frozen soil initially increased and then decreased with increase in the Na2SO4 content, whereas the internal friction angle as well as the strength exhibited a decrease followed by an increase with increase in the Na2SO4 content.
102-109
Mechanism of Downdrag for Floating H-Pile Subjected to Surcharge
摘要
This paper investigates the mechanism of downdrag for floating H-piles subjected to surcharge loads by performing three-dimensional numerical comparative analyses. The constitutive models and model parameters were calibrated using a centrifuge test. The downdrag of the H-pile can be reduced efficiently by enlarging the web properly, but enlarging the flanges was inefficient.
110-116
Improvement of Gypsiferous Soil Strength by Silicone Oil
摘要
Gypsiferous soils are usually stiff when dry, mainly because of the cementation of soil particles by gypsum. However, significant loss in strength and sudden increase in compressibility can occur when these soils are fully or partially saturated, and the dissolution of the cementing gypsum causes a high degree of softening of such soils. The problem becomes more complex when water flows through gypsiferous soil, causing leaching and movement of gypsum. This study examines the improvement of gypsiferous soil properties by using silicone oil to minimize the effects of moisture and gypsum loss. The work was conducted on artificial gypsiferous soil (30% Silber sand and 70% pure gypsum) treated with silicone oil in different percentages. Silicone oil was selected as an additive because of leakages of oil-related products from an oil refinery north of Iraq built on gypsiferous soil. Thus, this oil product provides a suitable analogue for that which has infiltrated the foundation soil of the refinery buildings. The results show that the silicone oil is a suitable material for modifying the basic properties of the gypsiferous soil, such as collapsibility and shear strength.
117-121
Design
Stability Express-Assessment of Landslide Prone Slopes During Pre-Design Development Work on Engineering Protection for Gas Pipeline and Power Transmission Line Routes
摘要
The object of the present investigations is a landslide prone slope along the route of Russia-Turkey power transmission and gas lines. The basic combinations of technogenic and native factors resulting in soil displacement with entrainment of the supports of the electric power transmission lines and endangering the gas line as well as variants of the interaction of the landslide with the pipes and supports are analyzed. Research on determining the working strength indices of the shifting soils landslide prone slope which interact with the pipeline is presented. An express procedure for slope stability assessment is developed; its use made it possible to propose variants of engineering protection for the gas pipeline and the electric power transmission lines.
122-127
Ecology in Construction
3D Transport of Solute in Deformable Soils with Different Adsorption Modes
摘要
Additional loading due to the weight of the waste in landfills results in consolidation and deformation of clay liners beneath, which will induce changes in the inner structure and permeability of the clay liners. Based on combination of Biot consolidation theory and solute transport theory, a three-dimensional coupled model describing solute transport in deforming soil has been proposed, taking account of the effect of consolidation on solute transport processes. The consolidation and transport equations are linked by choosing the permeability coefficients as the coupled parameter. The effects of different adsorption modes on solute transport processes in deforming soil under two conditions are studied: the solute source concentration remains constant or degrades with time. The solute concentration versus space with degraded-concentration source increases gradually and reaches a peak value at a certain depth in the vertical section or at a certain position in the horizontal section, and then decreases, which is very different from that with the constant-concentration source.
128-136
Geotechnical Monitoring
Structural Safety Security of Objects with an Underground Part by Transformation of Soil Properties: Alabyano-Baltic Tunnel in Moscow
摘要
Design and technological decisions aimed at ensuring the structural stability of a tunnel, built under complicated engineering-geological conditions, after a prolonged interruption of the construction work are examined. The measures taken to restore the carrying capacity of the reinforced concrete structures and eliminate water shows in the tunnel as well as the results of geotechnical monitoring are analyzed.
137-141
Erratum
Erratum to: Control and Reduction of Dynamic Disturbances During Vibratory Driving of Sheet Pile into Soil
142-142