Abstract
The prominent performance of wave elimination and energy absorption makes calcareous sand important and useful in infrastructure construction and protection engineering. Due to the high compressibility induced by remarkable intragranular void and irregular shape, calcareous sand presents different mechanical behaviors from common terrestrial sands. Considerable efforts have been made to explore the static and dynamic mechanical properties of calcareous sand. In this paper, a series of monotonous experiments have been performed on calcareous sand utilizing the electrohydraulic servo-controlled test apparatus designed by the Global Digital Systems Ltd (GDS). The effects of confining pressure and relative density on the mechanical properties of dry, drained, and undrained saturated sand were studied, and the underlying micromechanism of deformation and failure was discussed. It can be found that the residual stress of dry calcareous sand is independent of the relative density, while the peak stress and residual stress of drainage saturated sand have a positive correlation with the relative density. The increase of confining pressure makes the strain softening more remarkable and heightens the peak stress and residual stress. The stress-strain curve of calcareous sand can be divided into two portions: prepeak portion and postpeak softening portion. For the dry sand and drainage saturated sand, the softened part can be partitioned into three phases, i.e., accelerated phase, steady phase, and degradation phase, while the undrained saturated sand tends to hyperbolic softening. A mathematical model composed of a hyperbolic function and an inverted S-shaped function was formulated to describe the multiphase characteristic, in which the setting of parameter p expands its applicability. The experimental result validated the model, showing that the model can better describe the monotonic stress-strain relationship of calcareous sand. Besides, the physical meanings of model parameters were discussed.
Highlights
In the past few decades, sea-sand as a building material has been getting more attention
According to the results of the triaxial compression test, the monotonic stress-strain curve of calcareous sand can be divided into two portions: prepeak portion and postpeak portion
For the dry sand and saturated calcareous sand under drainage condition, the postpeak softening portion can be further divided into three phases from the perspective of softening rate, i.e., accelerated phase, steady phase, and degradation phase
Summary
In the past few decades, sea-sand as a building material has been getting more attention. It is significant to establish an effective and simple model that can accurately describe the mechanical characteristics of calcareous-sand under monotonic loading. E models have been widely used in practical engineering and are generally suitable for strain hardening materials such as footings on sand and clay They cannot be applied to geotechnical materials with strain softening characteristics due to relatively large deviation of calculation results. E constitutive relations established can be expressed by simple mathematical expression, and the influence of stress path can be considered Since the concepts such as double yield surface and anisotropic hardening criterion are introduced, the practical ability of the models is strengthened, and the complex constitutive characteristics of soil are described.
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