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This work presents an analysis of the relationship between strength parameters determined in the laboratory and the results of a cone penetration test with pore water pressure measurement (CPTU) of waste soils in the “White Seas” area in Cracow. Anthropogenic soil is an alkaline waste formed during the production of soda ash and deposited in the area of the former Solvay Sodium Plant factory in Cracow, Poland. Due to the large area of the land and numerous investment plans and completed buildings, there was a need to identify reliable functional relationships enabling the determination of the strength parameters of these soils based on the results of the CPTU. Statistical analysis showed that the best correlation with the test results was provided by two logarithmic functions in which the dependent variables were the effective friction angle and effective cohesion. The dependent variable for both cases was the corrected cone resistance qt. The functional relationship combined data from labour-intensive, long-lasting and costly laboratory measurements with quick and less expensive measurements, i.e., in situ CPTUs. The obtained relationships enable the determination of the strength properties of the subsoil of these anthropogenic soils.

Transportation demands in developing countries necessitate the use of underground infrastructure, notably tunnels, which also serve as storage spaces for vehicles and military equipment, expanding their utility. Mega Tunnels, defined as those with a diameter exceeding 10m, offer diverse functionalities, including facilitating the storage and movement of large equipment and establishing comprehensive operational systems for urban areas. However, ensuring the stability of these tunnels’ faces poses a significant challenge due to their larger diameter, making it a crucial research focus. This study investigates the impact of various geological strength variables, such as Young’s modulus and coefficient of lateral earth pressure, on Mega Tunnel face stability. Employing the numerical analysis-based computational tool Midas Gts Nx, three-dimensional modelling was conducted to analyze Mega Tunnels. A parametric study involving approximately 40 models was undertaken, focusing on key locations including the crown, invert, and vertical sidewalls. Variable parameters such as critical cover-to-diameter ratio (C/D), Young’s modulus, and coefficient of lateral earth pressure were examined. The findings highlight the significant influence of geological strength characteristics on tunnel face stability prediction. This research offers valuable insights for the planning and design of Mega Tunnels in urban areas during the preplanning phase, enhancing their efficiency and effectiveness.

The changes in the mechanical properties of collapsing walls under the influence of natural factors in the hilly area of southern China need to be determined. We systematically studied the influence of the interaction of dry density ρ (1.0, 1.1, 1.2, 1.3, 1.4 g/cm3) and moisture content ω (0.05, 0.1, 0.15, 0.2, 0.25 g/g) on the stability of four soil layers in a collapsing wall. The soil cohesion decreased with increasing soil depth. The cohesion force initially increased and then decreased with increasing ω and increased with increasing ρ; the internal friction angle was mainly affected by ω and decreased with increasing ω. The cohesion could be used to effectively characterize the stability of the collapsing wall. The shear strength index was modeled based on interaction between the dry density and moisture content (R2 > 0.95). The optimal combination of moisture content and dry density was obtained, and the collapsing wall was in the most stable state at a moisture content of 0.12–0.19 g/g and a dry density of 1.40 g/cm3. Based on the analysis of the critical height and safety factor (FS), the FS values of the sandy layer (C) was 0.53 and 0.57 for ω values of 0.25 g/g and 0.05 g/g, respectively. In the alternating process of soil wetting and drying, the basic properties of the soil changed; caused traceback erosion, and thereby affected the stability of the collapsing wall. Our study provides a theoretical basis for the investigation of the factors influencing the stability of collapsing walls.

The aim of this study is to determine the effect of changes in the phase composition of Al2O3–Si3N4 ceramics that were obtained using the method of mechanochemical solid-phase grinding on their resistance to the process of long-term thermal exposure, accompanied by the processes of oxidation and softening. The relevance of this research consists of determining the influence of the phase composition of ceramics on the change in their strength and thermophysical parameters, on the basis of which, we can draw a conclusion about the optimal composition of composite ceramics that have great prospects in the field of fire-resistant, heat-resistant, or radiation-resistant structural materials. During this study, the dynamics of the changes in the phase transformations of the xAl2O3–(1−x)Si3N4 ceramics, with variations in the ratio of the components, initiated by the thermal annealing of the samples, was established. According to the assessment of the phase transformations with variations in the ratio of the components, it was found that thermal annealing in an air environment at an Al2O3 concentration in the order of 0.3–0.5 M leads to the formation of an orthorhombic Al2(SiO4)O phase and an elevation in its contribution at concentrations above 0.5 M, which causes a rise in the thermophysical parameters and resistance to high-temperature degradation. During the heat resistance tests, it was found that the formation of the composite ceramics with the Si3N4(SiO2)/Al2(SiO4)O/Al2O3 phase composition results in an increase in the stability of their strength properties when exposed to thermally induced oxidation, which has a negative impact on their resistance to softening and a decrease in hardness. Moreover, the presence of the Al2(SiO4)O phase in the composition of the ceramics causes a slowdown in the processes of thermal oxidation of the Si3N4 phase under prolonged temperature exposure, alongside an increase in the degradation resistance of strength properties by more than 4–7 times, in comparison with the softening data established for single-component ceramics.

Understanding the interface shear strength is crucial for the design of geotechnical structures. This study investigates the effect of surface roughness on the interface friction angle, peak interface friction coefficient, and interface shear strength through direct interface shear tests. The experiments were performed on 10 samples of concrete and steel with the level of roughness varying and soil. The objective is to provide soil parameters for a site that is located around 6 km away to the south of Al-Amarah city, Southeast of Iraq where earthquakes hit frequently. The research is intended to investigate the effect of earthquakes on objects that are built in that particular region, by putting emphasis on the interaction between the soil structure and the roughness of the contact surface between the structural parts and the soil. In order to evaluate the roughness nature of structural materials, a test program was conducted using the SRT-6210 Digital Surface Roughness Tester. The average roughness parameter (R a) had the strongest association with shear parameters, and so it is the indicator to explain the shear behavior of sand‒concrete and sand‒steel interfaces. The direct shear box test was employed to find out the soil’s shear strength parameters as well as the interface shear strength parameters. The test shows a profound change in the shear strength characteristics of sand‒concrete and sand‒steel indispensable interfaces. As the roughness index increased. It depicted an upward slope of apparent shear strength and friction coefficient taken at the interface. The shear strength had increased by 25.13% when the roughness of the concrete was below 20 μm20{\rm{\mu }}{\rm{m}} and by 36.26% when the roughness of the steel was below 30 μm.\hspace{0.25em}30{\rm{\mu }}{\rm{m}}.\hspace{0.25em} Moreover, sand‒steel samples interface friction angle increased by approximately 31.5% with increasing surface roughness and sand‒concrete samples by 21.54%. The results also revealed that the peak interface friction coefficient (μp)\left(\mu p) increased with the increase in R a.

In this research, a multilayer feed-forward backpropagation error neural network has been used to predict the strength parameters of a concrete sample containing different additives. To achieve the most optimal neural network structure, the strength parameters of the concrete have been evaluated for different neural network arrangements. Control criteria are the use ofnumerical values of performance, the correlation between training functions, validation and,testing in the neural network, gradient and results of regression diagram to determine the most optimal neural network structure. It was found that the function of the neural network largely depends on its geometric structure. Revealed by the research findings, the most optimal prediction of the neural network has occurred in the case of using three layers with 30 neurons in each layer in the neural network. In this case, the numerical value of the neural network performance and the regression were obtained as 58.5 × (10-9) and 0.9846 , respectively. By determining the optimal neural network, different percentages of concrete raw materials based on the pre-performed experimental study are introduced to the selected neural network and the considered resistance parameters are predicted through residual analysis. According to the results, the differences between the predicted values of the neural network and the numerical values of the experimental study concerning the parameters of compressive, flexural, and tensile strength were also found to be equal to 1.68%, 1.92%, and 0.21%, respectively. Such a slight difference reflects the optimal accuracy of the chosen neural network in predicting the strength parameters.

This paper aims to determine the relationship between parameters of lower limb strength and balance in 5-8-year-old children practicing dance. Methods. So, an exploratory study was organized with a group of 24 children aged 5-8 years from the National Palace of Children of Bucharest. Tests used: Test 1 (15 jumps free arms), Test 2 - static balance (SB), Test 3 – lateral dynamic balance (LDB) and Test 4 vertical dynamic balances (VDB). Parameters: performance, front and back inside (LDB), left and right inside (VDB), avg. deviation. In this regard, establishing the relationship degree between lower limb strength parameters and balance in 5-8-year-old dancers depends on the number of negative correlations, especially between average deviation parameters.

Abstract Efficient and accurate acquisition of slope shear strength parameters is the key to slope stability analysis and landslide prevention engineering design. This paper establishes a back analysis method based on uniform design, artificial neural network, and genetic algorithm. It can obtain the shear strength parameters of slopes based on information such as the radius and center coordinates of the slip surface obtained from on‐site investigations. This method has been applied to engineering practice. The research results indicate that the stability of the waste dump slope is most sensitive to the response of the internal friction angle of the loose body, followed by cohesion, and least sensitive to the response of the soil volume weight. This method can effectively reduce the number of network training samples and efficiently and quickly determine the initial weights of the BP (abbreviation for back‐propagation) neural network. This method can efficiently and quickly conduct back analysis to obtain the shear strength parameters of slopes. Using the obtained shear strength parameters for slope stability calculation, the most dangerous slip surface abscissa error, ordinate error, and slip surface radius error are only 3.59%, 0.95%, and 1.83%. It is recommended to promote the back analysis method of shear strength parameters in engineering practice in the future.

A non-proportional reduction in strength parameters is widely used in slope stability assessment, but the current asynchronous reduction in strength parameters only considers the cohesion c and internal friction angle φ, which is suitable for slope stability assessment under static loads. Under seismic loads, however, tension at the rear edge of the slope often accompanies the appearance of ground cracks. In order to consider the relationship between tensile strength, cohesion, and the internal friction angle reduction coefficient, starting with the linear softening attenuation law of soil material strength parameters, a functional relationship between cohesion and internal friction angle is obtained. Then, considering that the failure of microelements in the tensile and shear zones conforms to the tension and shear of joint failure, the relationship between tensile strength, cohesion, and the internal friction angle reduction coefficient is derived. By establishing a homogeneous slope model and comparing and analyzing the progressive instability failure modes of slopes under static and seismic conditions, the stability and potential slip surface differences of slopes under two different working conditions are explored. The research results indicate that slope instability is a gradual, cumulative failure process under both static and dynamic conditions. The instability mode of the slope under static conditions is shear failure. In contrast, under dynamic loads, the instability failure of the slope is manifested as shear failure upward at the foot of the slope and tensile failure downward at the top of the slope. The stability coefficient of slopes under earthquake conditions is reduced by 17.3% compared to that under static conditions. Under earthquake conditions, the potential sliding surface under an asynchronous reduction in strength parameters is shallower than that under static conditions and deeper than that without an asynchronous reduction in strength parameters. Overall, the research results provide a reference for slope stability analysis and support design optimization under earthquake loads.

One of the prerequisites for the safe exploitation of surface mines is the stability of the working and final slopes of the mine. In order to ensure this, it is necessary to carry out detailed field and laboratory geomechanical tests of the soil and, based on the obtained results, make calculations related to stability analyses. The results obtained in this way are used for dimensioning the slope of exploitation slopes (excavation). Landslides occur when the ultimate shear strength is reached, and therefore, the adequate definition of shear strength parameters is one of the essential prerequisites for successfully solving the stability problem. Unlike earlier tests in Serbia, when the residual shear strength parameters were determined based on the usual conventional methods (direct shear apparatus, triaxial apparatus), this time, in addition to the direct shear apparatus, a ring shear apparatus was also chosen for testing. The paper shows the method of determining the residual shear strength parameters of high plasticity gray clays and siltstones of roof sediments from open pit mine Drmno, using direct and ring shear apparatus. The results show that the residual angle of internal friction for gray clays obtained with the ring shear apparatus is 9.9–10.8°, and for the siltstone, it is 11.8–12.9°, both of which are lower than the values obtained with the direct shear apparatus. In addition, correlations between the residual parameters of soil shear resistance and some physical indicators (plasticity index, clay content) are provided, showing high correlation coefficients. The proposed correlations should be used only when time and financial constraints prevent the execution of actual tests to determine residual shear strength, as concrete experimental procedures provide a much more reliable assessment of the residual strength properties of the soil.

The aim of the study is to examine the effect of functional threshold power training applied to young elite cyclists on power and strength parameters. 24 young elite level cyclists participated voluntarily. In our study, it was divided into two groups as Functional threshold training group (FTTG) and Traditional training group (TTG). Functional threshold training group n:12 (age 17 years, height 1,73±8,5 m., body weight 64,87±10.4 kg. and sports age 4,6±1.3), Traditional training group) n:12 (age 17 years, height 1,73±8,81 m., body weight 58,8±9,1 kg. and sports age 4,1 years). 30 sec Anaerobic power test, 20 min FTP test, 40 km. endurance and strength tests were applied to both groups as pre-post test. The obtained data were compared using the within-group Paired T test and the between-group Independent T test in the IBM SPSS Statistics 24.0 program. Traditional training group; Anaerobic power, 20 min FTP aerobics power, 40 km. endurance and strength pre-post test values improved. Functional threshold training group; Anaerobic power, 20 min FTP aerobic power, 40 km. endurance and strength pre-post test values were found to be more effective training development p