Relationship between granitic soil particle-size distribution and shrinkage properties based on multifractal method

Soil particle size distribution (PSD) essentially determines the soil's physical characteristics, including aggregate stability and porosity. Evaluating the PSD of sodic soils altered by reclamation is beneficial to the development of strategies for addressing land degradation. However, it remains unclear how to extract the features of PSD of sodic soils sensitively under gypsum reclamation. In this study, a total of 108 soil samples collected from a reclaimed sodic field were measured for PSD along with other soil properties, including hydraulic conductivity. Almost all the reclaimed sodic soil was measured to be silt loam, which was not obviously different from their original texture. The concentration, uniformity and symmetry of PSD of sodic soils have been quantified by fractal and multifractal geometry methods, in which the multifractal method provided more parameters than the fractal method to characterize the features of PSD more sensitively. The multifractal method offering predictive parameters (i.e., D1, D2, αmin and α0‐αmin) was able to significantly (p < 0.05) differentiate the features of PSD. The multifractal results indicated that the heterogeneity of PSD at 0–60‐cm depth was increased by reclamation, whereas the major particle size (silt) in these sodic soils decreased, and the combined treatment (i.e., using flue gas desulphurization [FGD] gypsum plus leaching water) created the most heterogeneous PSD. The redistribution of soil particle size caused by reclamation treatments resulted in the improvement of soil physical and chemical properties, showing increased soil aggregate diameter, raised total porosity, enhanced saturated hydraulic conductivity and decreased pH. The findings of this study bring a new opportunity to evaluate the effects of gypsum on the quality of sodic soils from the PSD perspective, which also provides a reference for evaluation of reclamation of other poor soils.Highlights The quantification of soil particle size distribution (PSD) of sodic soils remains unclear. A field evaluation using the multifractal method to characterize the PSD of sodic soil. With the reduction of silt particles, the heterogeneity of PSD was increased by reclamation. This study provides a new perspective for evaluation of the effects of gypsum on quality of sodic soils.

Plasticity characteristics of the soils (fine-grained) assume greater importance in view of engineering behaviour. It mainly depends on the clay mineralogical composition, predominantly controlled by physico-chemical phenomenon. This is due to the fact that the contradictory behaviour of the presence of the least active clay mineral kaolinite to most active montmorillonite in addition to Illite and other clay minerals, in different proportion. The contradictory behaviour of kaolinite and montmorillonite makes the study more complex. Shrinkage limit, among the Atterberg limits (plasticity characteristic) of the soils (fine-grained), associates with degree of packing, while the liquid and plastic limits classify the soils more qualitatively. The shrinkage and expansion of fine-grained soils lead to distress of foundation. The study related to volumetric behaviour of montmorillonite soils assumes a greater practical significance. Role of compaction energy on shrinkage behaviour of soils with particular reference to soil fabric also plays a vital role in the design of earthen-related structures. The potential shrinkage of soil is quantitatively described by the newly proposed method for testing expansive clayey soils, known as the ring shrinkage test. The measurements of lateral, vertical and linear shrinkages are provided by the test. Volumetric shrinkage and shrinkage limit along with compaction energy are determined alternatively by this method. The present experimental study mainly focuses on the effects of placement conditions, role of clay minerology and compaction effort on the shrinkage (linear, lateral and volumetric) behaviour of compacted fine-grained soils using ring shrinkage test. Correlations were developed between characteristics of compaction, i.e. optimum moisture content (OMC), maximum dry density (MDD), volumetric (VS) and lateral shrinkage (LS) with compaction energy (CE).KeywordsCompaction energyLateral shrinkageVolumetric shrinkage

Soil particle size distribution characteristics of different land-use types in the Funiu mountainous region

We monitored the occupancy of a functionally important non-coordinated water molecule in the distal heme pocket of sperm whale myoglobin over the pH range 4.3-9.4. Water occupancy was assessed by using time-resolved spectroscopy to detect the perturbation of the heme visible band absorption spectrum caused by water entry after CO photodissociation ( Goldbeck, R. A., Bhaskaran, S., Ortega, C., Mendoza, J. L., Olson, J. S., Soman, J., Kliger, D. S., and Esquerra, R. M. (2006) Proc. Natl. Acad. Sci. U. S. A. 103, 1254-1259 ). We found that the water occupancy observed during the time interval between ligand photolysis and diffusive recombination decreased by nearly 20% as the pH was lowered below 6. This decrease accounted for most of the concomitant increase in the observed CO bimolecular recombination rate constant, as the lower water occupancy presented a smaller kinetic barrier to CO entry into the pocket at lower pH. These results were consistent with a model in which the distal histidine, which stabilizes the water molecule within the distal pocket by accepting a hydrogen bond, tends to swing out of the pocket upon protonation and destabilize the water occupancy at low pH. Extrapolation of this model to lower pH suggests that the additional increase in ligand association rate constant observed previously in stopped-flow studies at pH 3 may also be due in part to reduced distal water occupancy concomitant with further His64 protonation and coupled protein conformational change.

A new fractional-order hyperchaotic memristor oscillator: Dynamic analysis, robust adaptive synchronization, and its application to voice encryption

Soil as a building material has been used in different forms such as mud, adobe, rammed earth and bricks. The present study focuses on producing Compressed Stabilized Earth Blocks (CSEBs) giving attention to the particle size distribution in the soil mixture. The literature established that compressive strength significantly depends on clay and silt content and 25% of clay and silt produce optimum results while no attention has been given to the amount of other, larger particles. Soil grading refers to the combination of different-size particles in a soil mixture. The correct selection of sizes in the correct proportion may cause improvements in CSEB properties. This paper explains the application of particle packing technology for the improvement of CSEB properties. The theoretical concepts provide a continuous particle size distribution, and the soil used for the experiments also has a continuous particle size distribution. The soil used in the experiments was subjected to washing to reduce the clay and silt content. Separated clay and silt and large particles of different sizes were added to the mixture to match particle size distribution to the optimization curves as explained in particle packing theories. The experimental results show that the CSEB properties can be significantly improved by modifying particle size distribution to fit the suggested optimization curves. According to the results, the compressive strength improved by more than 50% with different amounts of cement stabilization. Significant improvements in the dry densities and water absorption ratios of blocks were observed with this particle size modification.

Abstract. The objective of this research was to reveal the spatial variability of soil particle-size distribution heterogeneity. The farmland (48 m × 48 m) used in this study is located in the black soil region of northeast China and was divided into sixty-four 6 m × 6 m squares for sampling. The soil particle-size distribution was measured with a Mastersizer 2000. Soil particle-size distribution heterogeneity, the spatial variability of soil particle-size distribution heterogeneity, and the relationships between soil particle-size distribution heterogeneity and the clay, silt, and sand contents were studied by applying multifractal, geostatistical, and joint multifractal methods, respectively. The soil particle-size distribution had multifractal characteristics. Local information causing soil particle-size distribution heterogeneities were mainly low values of soil particle-size distribution; heterogeneities from the low-value side of the particle-size distribution were larger than those from the high-value side of the particle-size distribution. In the different soil layers, the degree of variation in soil particle-size distribution heterogeneities was moderate, with spatial correlation ranges of 37.82 m and moderate spatial dependences. At the single scale and multi-scale, the impacts of the clay, silt, and sand contents on the soil particle-size distribution heterogeneity changed with soil layer depth. The clay, silt, and sand contents had different degrees of influence on the spatial variability of soil particle-size distribution heterogeneity at the single scale and multi-scale. Multi-scale analysis could better reveal the degrees of influence of the above soil properties on the spatial variability of soil particle-size distribution heterogeneity. The results of this study enrich the knowledge of the spatial variability of soil properties and provide a reference and additional information for the quantitative characterization of soil particle-size distribution heterogeneity and soil management in this research area. Keywords: Geostatistics, Multifractal analysis, Relationship, Soil property.

Evaluation of different representations of the particle-size distribution to predict soil water retention

Fractal evaluation of particle size distributions of chromites in different comminution environments

Estimation of reference bulk density from soil particle size distribution and soil organic matter content

Runoff sediment from disturbed soils in the Lake Tahoe Basin has resulted in light scattering, accumulation of nutrients, and subsequent loss in lake clarity. Little quantified information about erosion rates and runoff particle‐size distributions (PSDs) exists for determining stream and lake loading associated with land management. Building on previous studies using rainfall simulation (RS) techniques for quantifying infiltration, runoff, and erosion rates, we determine the dependence and significance of runoff sediment PSDs and sediment yield (SY, or erodibility) on slope and compare these relationships between erosion control treatments (e.g., mulch covers, compost, or woodchip incorporation, plantings) with bare and undisturbed, or ‘native’ forest soils. We used simulated rainfall rates of 60–100 mm h−1 applied over replicated 0·64 m2 plots. Measured parameters included time to runoff (s), infiltration and runoff rates (mm h−1), SY (g mm−1 runoff), and average sediment concentration (SC, g L−1) as well as PSDs in runoff samples. In terms of significant relationships, granitic soils had larger particle sizes than volcanic soils in bulk soil and runoff samples. Consequently, runoff rates, SCs, and SYs were greater from bare volcanic as compared to that from bare granitic soils at similar slopes. Generally, runoff rates increased with increasing slope on bare soils, while infiltration rates decreased. Similarly, SY increased with slope for both soil types, though SYs from volcanic soils are three to four times larger than that from granitic soils. As SY increased, smaller particle sizes are observed in runoff for all soil conditions and particle sizes decreased with increasing slope. Copyright © 2008 John Wiley & Sons, Ltd.

The need for better characterizing the properties of field compacted soils during construction is important in ensuring the quality of construction. Standard laboratory compaction tests for soil, a three-phase material, are often viewed as the compaction standard for earthen fills. However, these laboratory tests were developed to simulate the compaction energy of a particular compactor-soil-lift combination. For this study, a field compacted CL soil (liquid limit of 42) with several properties (dry unit weight-moisture relationship, maximum dry unit weight, optimum moisture content, void ratio and air void content) was compared to the Standard Proctor (SP) and Modified Proctor (MP) tests. In the field, the CL soil was compacted at 200 mm (8-in) lift thickness using a popular compactor. Nuclear density gauges was used to measure the lift densities and moisture contents. The dry unit weight-moisture content relationships for SP and field compacted curve didn’t overlap at all. The maximum dry unit weight of field compacted CL soil was 8 to 9 pcf higher than the SP compacted soils. All the other properties studied showed notable differences between the field compaction and laboratory compaction. The void ratio and air void contents had the highest differences in the SP and field compacted CL soil. A new surface penetrometer (SP-CIGMAT) was developed and used to evaluate compacted soil undrained shear strength (su) and CBR during the construction. This device can be easily attached to any construction vehicle to perform tests on compacted soils during construction. Based on the limited field data and laboratory tests, non-linear and linear correlations between the SP-CIGMAT deflection and compacted soil properties have been developed.

Effects of diatomite on soil consistency limits and soil compactibility

A microseismic (MS) monitoring system in a mine can monitor the MS signals generated by coal rock rupture and blasting waves and can distinguish the two types of waves more clearly to monitor and analyze the rupture and evolution process of coal rock. According to the nonlinearity characteristics of the waveform, the fractal characteristics of a mine’s MS and blasting waves are analyzed by simple fractal and multifractal theory, and the simple fractal dimension [Formula: see text] and multifractal parameters are obtained, respectively. Results show that the simple fractal dimension [Formula: see text] reflects the complexity and frequency structure of the wave. The simple fractal dimension [Formula: see text] of a blasting wave is larger than that of a mine MS wave, which indicates that the blasting wave is relatively complex with higher frequency, while the mine MS wave is relatively simple with lower frequency. However, the simple fractal dimension [Formula: see text] can only describe the wave integrity features, not the local features. The multifractal parameters can describe the local characteristics of the wave more finely, and the multifractal spectrum describes the probability information of the singularity exponent [Formula: see text]. The singularity exponential range and multifractal spectral width [Formula: see text] of the blasting wave are smaller than those of the mine MS wave, which indicates that the probability measure of distribution unevenness and the degree of partial parameter fluctuation of the blasting wave are more severe than those of the mine MS wave. Wave signal analysis based on simple fractal and multifractal methods can not only obtain the characteristics of the wave strength and spectral structure but also other important information, such as local singularity. Therefore, it is possible to more clearly and conspicuously identify mine MS and blasting waves, so that coal rock rupture can be monitored more accurately.

Separating provenance and palaeoclimatic signals from particle size and geochemistry of loess-palaeosol sequences using log-ratio transformation: Central European loess belt, Czech Republic