Influence of the Zinc and Fibre Addition in the Diet on Biomechanical Bone Properties in Weaned Piglets

The effects of the zinc and fibre source in piglets’ diet on the bone mineral content, density, and strength parameters of the femur were investigated using 24 piglets fed a diet supplemented with either lignocellulose (LC) or potato fibre (PF). Half of each group of piglets consumed a diet with ZnSO4 monohydrate or with zinc glycinate (ZnGly). The diets contained similar amounts of lysine, energy, and fibre. Bone mineral content and density were over 9% higher in pigs receiving diets with ZnGly than in animals fed diets with ZnSO4. Moreover, ZnGly strongly improved maximum and elastic strength (by 25.7 and 20.0%, respectively, p < 0.0001) and bone stiffness (by 29.4%, p < 0.0001). Only the mass of the femur was affected by the type of fibre in the diet, as the femurs of piglets fed diets with LC were over 7% (p < 0.0001) heavier than in piglets fed diets with PF. The intake of digestible zinc and the zinc content in the blood serum were positively correlated with the measured bone parameters and, depending on the parameter, “r” ranged from 0.749 to 0.866 and from 0.400 to 0.479, respectively. It can be concluded that bone parameters are affected more strongly by the organic than inorganic source of zinc.

Influence of calcareous nodules content on scaling effect in shear strength of cohesive soil containing calcareous nodules

The difference in the shear strength and other characteristics of the cohesive soil containing calcareous nodules (CSCN) between samples with large size and corresponding scaling size, which is called scaling effect, is significantly affected by its calcareous nodule content (CNC) of the gradation composition. However, current researches rarely reveal the influence of the CNC on the scaling effect in shear strength of samples. In this study, how and why the CNC affects the scaling effect in shear strength were explored. Then a method to reduce the scaling effect based on the reason for influence was proposed. Results show that the correlation between the scaling effect in shear strength and the CNC presents a step curve. This is attributed to that it is easier to form a skeleton effect in samples with scaling size for the same CNC. Considering the skeleton effect, a calculation model for the shear strength parameters of CSCN samples with large size is proposed to reduce the scaling effect. This paper demonstrates that the proposed calculation model provides an access to obtain calculated shear strength parameters of CSCN samples with large size by using measured results of samples with corresponding scaling size.

Slope stability calculation method for highwall mining with open-cut mines

Slope stability is a prominent problem for the efficient application and promotion of highwall mining technology, especially when mining residual coal under high and steep end-slope conditions. This study proposes the concept of target time pillar strength based on the required coal pillar service time. Creep tests were performed to measure the time-varying properties of coal shear strength parameters under different loads, and a time-varying function was established by regression. The highwall mining length is divided into three categories based on discontinuous structural plane theory, including goaf, yielding, and elastic zones, all of which are considered to have resistances against shear stress. The basal coal seam is prone to weakening owing to the weight of overlying strata, which may shift the slope failure mode from circular to sliding along the weak layer. Numerical modeling was used to study the influence of the bearing stress and target time strength on the development of the yielding zone at the coal pillar ribs. The coefficients of the three zones were determined, and the temporal and spatial evolution patterns of the shear strength parameters of the weak layer were acquired. A slope stability calculation method is proposed based on rigid body-limit equilibrium theory that can quantify the influence of highwall mining operations on slope stability, which is significant for popularizing highwall mining technology.

Effect of UV-Irradiation and Ozone Exposure on Thermal and Mechanical Properties of PLA/LDPE Films

The mechanical properties of polymer composites based on polylactide vary significantly over a wide range of values. It has been established that photodegradation of low-density polyethylene – polylactide blends occurs both in the amorphous and in the crystalline phase of the PLA matrix, which leads to deterioration of the mechanical properties of the studied mixtures. Ozonolysis affects the strength parameters of polylactide-polyethylene samples as well as photodegradation. By the differential scanning calorimetry it is determined that the melting point of polylactide decreases by 2-4 °C, the glass transition temperature - by 1-3 °C, while the degree of crystallinity increases by 3-6%. In the process of ozonolysis, the thermophysical characteristics of PLA/LDPE have changed.

Numerical Modeling of Shallow Foundation Behavior Using Soft Soil Model

This study discusses the results of simulation a finite element analysis of the load-settlement curve using soft soil model of shallow foundation subjected to axial load rested on three different types of clayey soils, it was considered different shear strength parameters (C=16, C=25, and C=70). It was concluded for clayey soil of C=16, there was a match to the experimental load – settlement curve using the soft soil model. It was also observed increase in the foundation width led to an increase in bearing capacity, however, bearing capacity increased by around (79 %) for an increase in footing width of (6.25), so it was about (144%) for (12.5).

PROPERTIES MEASUREMENT AND APPLICATIONS OF SOME GEOPOLYMERS IN DRY AND WET SAND

The interest in reducing carbon emissions due to the large number of industrial wastes led to the civil engineering sector’s interest in using these products for easy access and for their unique advantages in improving raw materials after mixing them and determining their optimal use ratios. Through experiments and continuous studies, three types of geopolymers were used for this study based on poor sandy soil and mixing it in certain proportions with geopolymers, recording and analysing the results and using it in the practical experiment by using a special model to shed the loads on a square footing and drawing the load - settlement curve that showed the improvement of the sandy soil’s ability to resist shear by increasing the loads and reducing the settlement in the foundations. the laboratory test proved improvement in the shear strength parameters in sandy soil after blending with geopolymers.

Investigation of Changes to Triaxial Shear Strength Parameters and Microstructure of Yili Loess with Drying–Wetting Cycles

This research examined the drying–wetting cycles induced changes in undrained triaxial shear strength parameters and microstructural changes of Yili loess. The drying–wetting cycles were selected as 0, 1, 3, 5, 10, 20 and 30. Then, we collected Yili loess samples and performed unconsolidated-undrained (U-U) triaxial shearing tests to ascertain the variation in shear strength parameters with drying–wetting cycles. Additionally, we investigated the microstructural changes of Yili loess samples under drying–wetting cycles simultaneously via nuclear magnetic resonance (NMR) and scanning electron electroscopy (SEM). Finally, we established a grey correlation model between shear strength and microstructural parameters. Under U-U conditions, the prime finding was that the loess’s shear strength parameters changed overall after drying–wetting cycles; in particular, the internal friction angle φ dropped significantly while the cohesion c changed only slightly during cycles. For all the cycles, the first cycle gave the highest change. Soil morphology deterioration was evident at the initial stage of cycles. During the entire drying–wetting cyclic process, pore size distribution showed progressive variance from two-peak to a single-peak pattern, while both porosity and the fractal dimension of pores increased gradually towards stability. Soil particle morphology became slowly simple and reached the equilibrium state after 20 drying–wetting cycles. Under cyclic drying–wetting stress, the shear strength parameter changes were significantly correlated to microstructural modifications. This investigation was related to loess in the westerly region. The findings were expected to provide new insight into establishment of the connection between microstructure and macro stress–strain state of loess. To some extent, it provided a theoretical basis for the prevention and control of loess engineering geological disasters in Yili, Xinjiang and other areas with similar climate and soil types.

CHANGE IN STRENGTH PARAMETERS OF DISPERSED SOILS AFTER HIGH-FREQUENCY VIBRATION

The use of the technology of high-frequency sheet piles driving or extraction in conditions of weak, structurally unstable soils inevitably leads to a change in the structure of the soil. This is especially true for buildings which fall into the zone of influence. Often, foundation for historical buildings is water-saturated sands, spread by fluid and fluid-plastic clay soils. In the process of external dynamic action, the soil foundation is been destructing, so their strength and deformation parameters are reduced. In this case, the result of vibration effects on a dispersed water-saturated sample can be both compaction for sandy soil and decompaction of clay soils. These changes lead to additional deformations of buildings and structures of the surrounding area. Therefore, the issue of assessing the limits of applicability of vibration technology in certain conditions is relevant. The object of the study is the changes in the properties of clay soils of various consistencies after exposure to vibration. The results of laboratory studies to determine the strength parameters of dispersed soils after high-frequency vibration are presented. The results of field measurements by CPT "before", "after" vibration immersion and vibration extraction of sheet piles are considered. Comparison of the results of field and laboratory studies is carried out to identify patterns of change in the strength characteristics of weak soils under the influence of vibration loads. A tendency towards a decrease in the strength parameters of dispersed soils is shown. Currently, due to the insufficient number of laboratory and field studies to study the effect of high-frequency vibration on the change in the strength parameters of weak water-saturated clay soils, it is not possible to identify a clear dependence of the change in parameters on the time and frequency of vibration.