Soil Mass Research Articles

Energy required to cut the soil with No.4 circumferential knives of the large rotor of the straight-through rotary ripper

Introduction. To solve the problem of the fast and high-quality road construction, when economic facilities and settlements are located at a considerable distance from each other, cannot be solved without the use of a complex of continuous units. The continuous ditch forming unit and the tunneling unit contain straight-through rotary rippers. Insufficient theoretical studies in this area do not enable to calculate the interaction of the elements of a direct-flow rotary ripper with the soil. Therefore, there is a need for theoretical studies to determine the energy parameters of the large rotor, in particular, that which is necessary for cutting the soil with the No.4 circumferential knives of the large rotor.The research method. The methods for calculating the required energy inputs: to separate the reservoir from the soil mass; separation of the reservoir into fragments; creating a gap in the soil mass; deformation of a part of the soil mass; overcoming the friction of the ground on the edge of the blade; overcoming the soil pressure on the front surface; movement of the soil by the front surface; overcoming the friction of the ground on the front surface have been developed.Results. On the basis of the developed methods, the parameter calculations were made. From the plane models and the spatial model of the forces of interaction with the soil of the circumferential knives No.4 of the large rotor, resultant forces, their components, normal forces were revealed. The force of friction of the soil on the edge of the blade and the front surface of No4 circumferential knives was calculated. The volumetric energy required for cutting with No.4 circumferential knives when mining one cubic meter of soil with a straight-through rotary ripper is calculated.Conclusion. The energy required to drive the circumferential knife includes separating the seam from the soil mass; separation of the reservoir into fragments; creating a gap in the soil mass; deformation of a part of the soil mass; overcoming the friction of the ground on the edge of the blade; overcoming the soil pressure on the front surface; movement of the soil by the front surface; overcoming the friction of the ground on the front surface. As a result of the calculations, the total energy required for cutting with No.4 circumferential knives, when mining one cubic meter of soil with a straight-through rotary ripper, was 9110 joules.

Mechanical and hydraulic characteristics of unvegetated or vegetated loess soils amended with xanthan gum

With the development of western and central China, the increasing construction of transportation infrastructures (e.g., roads, railways, etc.) has been producing a large number of man-made slopes in loess regions. Biopolymer as an eco-friendly stabilizing material, has a great potential to amend soils for the purpose of ground improvement and slope stabilization, with its application in vegetated soils particularly at the initial growing stage to support vegetation growth as well as offer reinforcement to unprotected soils being reported recently. In the current study, the contribution of xanthan gum (XG) to both mechanical and hydraulic behaviors of the unvegetated and vegetated loess soils subjected to climatic wetting–drying cycles under the impacts of degree of compaction and biopolymer content are explored, whilst the effectiveness of the two XG-based soil reinforcing methods (with and without vegetation) are compared. Results indicate that XG treatment improved the water-retention capacity of loess soils to an extent that even the degradation of water retention upon initial wetting–drying cycles could be mitigated particularly at higher degrees of compaction. The strengthened shear resistance of loess soils was observed, mainly attributed to the increased soil cohesion, whilst the friction angle remained almost constant. The unvegetated loess soils basically had an increased cohesion proportional to the XG content up to 1.00% of the dry soil mass, whilst the vegetated soils had the highest soil cohesion at a fixed XG content of 0.50% which corresponded to the mostly promoted vegetation growth. Although a dense soil structure inhibited the seed germination and growth of sprouts and roots, it contributed to the overall shear strength of the vegetated soils similar to its effect on the unvegetated soils. XG amendment outperformed planting vegetation at enhancing soil shear strength at a degree of compaction of 95% (comparable to those adopted for design of highway subgrade), whilst providing XG in combination with vegetation was able to result in a more sizable strength increment over the summation of gains in strength by utilizing XG and vegetation separately, suggesting the considerable potential of XG in assisting vegetated soils for ecological slope stabilization. The results obtained from the current research support the broader usage of biopolymers (either used alone or in combination with vegetation) as reliable geotechnical engineering materials in practical implementations.

A Machine Learning-Driven Approach to Uncover the Influencing Factors Resulting in Soil Mass Displacement

For most landslides, several destabilising processes act simultaneously, leading to relative sliding along the soil or rock mass surface over time. A number of machine learning approaches have been proposed recently for accurate relative and cumulative landside displacement prediction, but researchers have limited their studies to only a few indicators of displacement. Determining which influencing factors are the most important in predicting different stages of failure is an ongoing challenge due to the many influencing factors and their inter-relationships. In this study, we take a data-driven approach to explore correlations between various influencing factors triggering slope movement to perform dimensionality reduction, then feature selection and extraction to identify which measured factors have the strongest influence in predicting slope movements via a supervised regression approach. Further, through hierarchical clustering of the aforementioned selected features, we identify distinct types of displacement. By selecting only the most effective measurands, this in turn informs the subset of sensors needed for deployment on slopes prone to failure to predict imminent failures. Visualisation of the important features garnered from correlation analysis and feature selection in relation to displacement show that no one feature can be effectively used in isolation to predict and characterise types of displacement. In particular, analysis of 18 different sensors on the active and heavily instrumented Hollin Hill Landslide Observatory in the north west UK, which is several hundred metres wide and extends two hundred metres downslope, indicates that precipitation, atmospheric pressure and soil moisture should be considered jointly to provide accurate landslide prediction. Additionally, we show that the above features from Random Forest-embedded feature selection and Variational Inflation Factor features (Soil heat flux, Net radiation, Wind Speed and Precipitation) are effective in characterising intermittent and explosive displacement.

Forest soil carbon storage in 10‐year‐old Douglas‐fir plantations of western Oregon and Washington remains similar to pre‐harvest

AbstractForests around the world, and in the case of this study, the coastal Pacific Northwest United States, store large amounts of carbon, both above ground in the trees and below ground in soils. Understanding the effects of forest disturbance, including timber harvesting, is important in order to evaluate the role that forestry plays in the global carbon cycle. Soil carbon can be difficult to assess with enough precision to detect the kinds of changes that are expected, yet a series of small changes over time in the same direction could have important cumulative effects. In this study, eight randomly selected Douglas‐fir forest stands in Oregon and Washington were sampled at 300 points each using a fixed‐depth sampling approach to attempt to detect a 5% or higher change in soil carbon storage to 1 m, longitudinally from pre‐harvest to 10 years post‐harvest. There was moderate variability in results over time at individual sites, with some sites decreasing slightly and others increasing slightly. Only two sites achieved lower than the 5% minimum detectible difference target. The remaining six sites were able to detect 5.7%–10.7% differences. In one case, an unexpectedly large increase in mineral soil carbon 10 years post‐harvest occurred without clear explanation. On average, forest floor carbon stores were 20% larger 10 years post‐harvest than pre‐harvest. Even with the large increases excluded, both the fixed‐depth approach and equivalent soil mass correction showed there was no significant change in mineral soil carbon stores to 1 m at 10 years post‐harvest in the region.

Enhancing Dynamic Shear Resistance and Efficient Micro-Void Reduction of Expansive Soil Using Activated Nano-Desilicated Fly Ash

Excessive swelling and high compressibility of soil have posed countless challenges such as poor dynamic shear strength for engineers dealing with cyclic loading in pavement structure. To address this challenge, the durability and mechanical properties of the investigated subgrade were treated with 10%, 20%, and 30% of activated nano-disilicate fly ash (NDFA) to the dry mass of the subgrade soil. A series of swelling pressure tests, One-dimensional compression tests, and dynamic triaxial (DT) tests were conducted on the samples fabricated using altered moisture content. The findings demonstrated that the swelling pressure and compressibility of the NDFA-treated specimens significantly decreased to an average of 15.3% and 18.4% respectively upon 20% inclusion of NDFA beyond which the swelling stress and compressibility values further decreased signifying the impact of NDFA on the expansive subgrade. The consolidation results also revealed that the treated soil’s consolidation parameters greatly decreased compared to the untreated soil with a high void ratio and compression index (Cc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{c}$$\\end{document}). The dynamic shear resistance of the subgrade soil increased by 36% upon the addition of 10% NDFA content compared to the untreated soil which portrayed a very low resistance against dynamic shear modulus (Gmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${G}_{max}$$\\end{document}) with a corresponding high damping ratio. The investigation revealed a strong correlation between Cc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{c}$$\\end{document} and dynamic shear modulus which is closely correlated to a coefficient determination of 0.99 due to the parameter’s dependency on porosity, particle shape, and stiffness.

Increasing the strength of potato digger elevator rods

Abstract Currently, high-quality steels are used to increase the reliability of potato digging machines and the durability of elevator rods. Recently, new materials, new technologies and non-metallic materials that are not inferior in strength to steel have been used in agricultural machines. Such materials significantly reduce the mass of the working parts. This article examines the deformation of a new elevator rod design due to the action of soil and tuber-bearing mass. The rods, covered with double-cavity rubber profiles, vibrate the component of the potato heap. During vibrations, in addition to static deformations, dynamic deformations occur, depending on the magnitude of the impact force. As a result, it was found that to eliminate the loss of tubers between the bars of the separating elevator, given the maximum deflection value of 0.03 m and the weight of the soil-tuber-bearing mass, the rubber bar must have the following parameters: elasticity model E = 50 N/mm2; rod perimeter 11x11 mm; the maximum jump height of a mass weighing 130 kg is no more than 0.6 m.

Accurate Analysis of Stand-up Time Rock Collapse When Inlet Tunnel Excavation is Carried out in there are Cracked and Broken Rock Formations and a Poorly Silty-clay Soil Profile

The condition of the rock formation and the poor stability of the type of soil mass (problematic soil) in the tunnel excavation route greatly influence the achievement of the collapse (stand-up time) that will occur. The thickness of the overburden pressure above the tunnel opening is often difficult to meet, so in the inlet zone as well as in the out-let zone, slope collapse often occurs and disrupts the work implementation schedule. On the slope of the inlet excavation location, there are also silt formations with outcroppings. Rocks from small to large sizes and there are even rock masses that are cracked so that the quality or strength of the rock is unstable when exposed to the equipment used when tunnel excavation work is carried out. This research method was carried out using an approach that corresponds to the Rock Quality Designation (RQD) value with the Rock Mass Rating (RMR) value which will provide a classification of rock classes and excavation methods. The data used in this research is rock data at the tunnel inlet of the Rukoh Dam Steering Building. From the RQD and RMR data and soil physical properties obtained in this research, analysis was carried out using the empirical approach introduced by Bieniawski. The results obtained from the in-situ test drilling work, the results of which were stored in the core box at the tunnel inlet, obtained an RQD value equal to 32.5% and an RMR value equal to 15. The RMR value shows that the rock at the tunnel inlet falls into the very category poor. With a tunnel opening as wide as 6.60 M, the stand-up time at the tunnel in-let is less than 30 minutes.

Application of the Discrete Element Method to Landslides

Civil engineering is defined as all construction related to the ground. In other words, civil engineering is only possible where there is soil. Construction professionals should not face any obstacles when building sustainably in any soil context. Knowledge of the altimetric state, including hills, mountains, valleys, etc., and the subterranean state, including obstacles such as compressible soil, holes, water tables, and rock masses, is crucial to consider before designing infrastructure. This includes the buried part of a structure and the angle of the natural slope in the superstructure to avoid landslides in the infrastructure. Landslides are natural disasters that have had a devastating impact on several populated areas in Cameroon, resulting in numerous fatalities. The most recent landslides recorded in our country occurred in NGOUACHE, MBANKOLO, MOBIL GUINNESS, among others. Preventing disasters requires an understanding of the relationship between construction and landslides to minimize their occurrence and impact. It is important to campaign for sustainable construction that respects the environment. Understanding landslides involves both destructive and non-destructive approaches. This article presents numerical methods for analysing and predicting phenomena. Among these methods, we focus on the discrete element method, which represents the medium as an assembly of circular, rigid particles. We examine three cases to observe the behaviour of the supporting soils and determine the fracture surface. Additionally, we compare our results with those found in the literature.

Application of SPH in rheology model for the submerged landslide

The seafloor environment is prone to rapid changes caused by landslides, which can result in significant human, financial, and environmental consequences. Previous research efforts have primarily focused on studying rigid submerged landslides using physical experiments and mesh-based numerical simulations. However, there is a need to investigate deformable soil masses due to their inherent complexity. In the current study, a smoothed particle hydrodynamics (SPH) method was developed to examine the behavior of submerged landslides. Three rheological models, namely Bingham, Herschel–Bulkley (H–B), and μ(I), were applied to characterize the properties of the sediment materials. The SPH governing equations were modified at the interface between the water and sediment phases to account for the density discontinuity between them. The viscosity term at this interface was determined using the Owens equation. The effective pressure, a crucial parameter in rheological models, was appropriately modified to reflect the influence of the water column on the sediment particles, utilizing a simple algorithm. For the μ(I) rheology, separate equations were applied to describe the behavior of dry and saturated conditions. Additionally, the Mohr–Coulomb criteria were utilized in the Bingham and H–B models to determine the yield stress. To validate the effectiveness of the proposed modeling approach, a column failure scenario was first simulated. Subsequently, a rigid submerged landslide was investigated to assess the capability and validity of the proposed framework in accurately capturing surge wave generation and calibrating the boundary friction factor. Finally, two deformable submerged landslides involving different materials, namely sand and glass beads, were simulated and compared with previous experimental and numerical studies at different time steps. Through these comprehensive investigations, the current understanding of the complex behavior exhibited by submerged landslides is enhanced, and valuable insight into landslide dynamics is provided.

UCS and microscopic experimental study of coconut coir fiber-waterborne epoxy resin composite modified calcium sand

To address the issues of high porosity and low strength in calcium sand of artificial islands, this study focuses on improving the calcium sand’s mechanical properties. The effects of WER curing methods and coconut fiber modification on the UCS and microscopic mechanisms of calcium sand are investigated. The results indicate that both fiber incorporation and the increase in WER ratio can enhance the unconfined compressive strength of calcareous sand, with the addition of a certain amount of coconut coir fiber showing a more significant strength increase. The optimal recommended dosage of WER is 15%, which results in an UCS of 1218 kPa, an increase of nearly 4.27 times compared to 9% WER dosage. Coconut coir fiber has good tensile strength that can improve the compressive strength of calcareous sand after curing. The UCS of calcareous sand cured with a fiber content of 0.3% to 0.5% is increased by 1247 kPa to 1792 kPa compared to cured soil with no fiber. The strong binding nature of WER addresses the issue of large porosity in calcareous sand. Together with the penetrating coconut coir fibers, it forms a three-dimensional reticular framework structure, thereby enhancing the compressive performance of the calcareous sand-cured soil mass.

Analysis of Tribological Properties of Hardfaced High-Chromium Layers Subjected to Wear in Abrasive Soil Mass.

This article presents the results of abrasion wear resistance tests of wear-resistant steel and surfacing under laboratory conditions and natural operation. Abrasion wear resistance determined on the basis of the study by determining geometrical characteristics of the alloying additives using computer image analysis methods, as well as examining the changes occurring on the surface of the workpieces and their wear intensity. Based on the results obtained from laboratory tests, it was noted that AR steel exhibited 14 times greater wear than the padding weld. This wear is affected by alloy additives, which, for the padding weld, are chromium additives. The microstructure image shows that soil mass had a destructive effect mainly on the matrix of the material, whereas in the areas with high concentrations of chromium precipitates, this effect was significantly weaker. The operational test results showed that within the area of the tine subjected to hardfacing, the material loss was lower than that for the same area of the tine in the as-delivered state. For the hardfaced tine, a 7% loss of volume was noted in relation to the operating part before testing and following the friction process. However, for the operating part in the as-delivered state, this difference amounted to 12%.

Оценка ущерба, наносимого загрязняющими веществами от выхлопных газов транспортных средств при реконструкции автомобильной дороги

Purpose: assessment of damage caused by pollutants from vehicle exhaust gases during highway construction. The roadbed is one of the most important elements of a highway structure, presented in the form of a mass of soil and receiving static and dynamic loads from vehicles. The increasing intensity of road transport has a negative impact on the environment. The main causes of environmental damage are overloads at intersections, and their effects are delayed in time. For example, when a city highway is laid through an uninhabited area, the damage incurred is less than when the highway passes through densely populated residential areas and is adjacent to urban areas. Poor traffic management leads to environmental damage. The volume of emissions of harmful substances is determined by the mileage of vehicles, depends on various factors and is related to the total fuel consumption. An urgent task is to supplement the Methodological Recommendations for the selection of rational roadbed structures and their feasibility study with an indicator that takes into account environmental pollution, including greenhouse gas emis such as this is required in accordance with [1]. Methods: Taking as a basis the existing methodological recommendations for the selection of rational subgrade structures on weak foundations and their feasibility study [2], calculations were made on the basis of which it is possible to draw a conclusion about the amount of exhaust gases emitted by reducing the flow rate during activities for the reconstruction of the highway. The main concept underlying the methodological document is the optimization of design solutions based on their comprehensive technical and economic assessment, carried out in terms of capital and operating costs, significant socio-economic effects and the duration of the construction period. Results: a feasibility study and a technical and economic comparison of design solutions for the reconstruction of the highway were carried out in terms of widening the roadbed built on soft soils. Practical significance: Calculations are included in the basis of practical recommendations for the use of design solutions for the construction of roadbeds on soft soils, which gives a clear idea of the technical and economic feasibility oftheir use in various operating conditions.

APPROACHES TO ASSESSING THE STABILITY OF BANK PROTECTION STRUCTURES OF WATERBODIES: ANALYSIS OF CONSTRUCTIONS AND MODELS FOR THEIR CALCULATION

The article analyzes the theoretical foundations for determining the stress state in a soil mass and the design of fastening the bank slope of reservoirs. Scientific research and theoretical principles on determining the forces that act on a bank protection structure have been systematized. Methodological approaches to the static calculation of bank protection for indirectly vertical structures are proposed, taking into account the relationship between the load on the structure and its deformation. The purpose of the research is to ensure the stability and reliability of bank protection structures and to substantiate directions for improving technical solutions in modern conditions. The work analyzes the use of various types of slope fastenings for bank protection structures in accordance with the requirements of State construction standards. It is proposed to focus research on sheet piling shore fastenings, as a modern and progressive technology for bank protection. The "soil massif - fastening structure" system is considered as a calculation model in the form of a one-sided type, which is an elastic element, which makes it possible to apply the modern apparatus of the theory of elasticity in considering this problem. This makes it possible to accept a linear relationship between stress and strain and obtain sufficient accuracy, which is confirmed by the available results of domestic and foreign research. For calculations of deformations, and assessment of the strength and stability of soil massifs and foundations, it is proposed to pay direct attention to the characteristics of the mechanical properties of soils, while three stages of foundation deformation are considered. The formulated differential equations of the equilibrium of the soil massif make it possible to solve a wide range of issues related to the limit equilibrium and to obtain the calculated parameters of the pressure of earth masses on the retaining walls of shore fortifications of the oblique-vertical type. The results of the research analysis are recommended for use in determining the main loads on hydraulic structures, substantiating technical solutions for the development and improvement of slope and slope-vertical types of bank protection of reservoirs.

Diffusion mechanism of fracture grouting in rock mass with flowing water

Grouting is a widely used geotechnical procedure known for its strong empirical properties. It has been extensively utilized for sealing subterranean water and strengthening soil and rock masses in their original locations in underground mining and underground space development. The diffusion mechanism of grouting in fractured rock is affected by the geological environment and slurry performance, which should be better revealed and characterized. In this paper, we take the surrounding rock of the roadway as the research object, consider the stress condition of the injected rock and time-dependent viscosity of the slurry, and establish fracture grouting diffusion model based on the rock composite fracture criterion. The grout strengthening mechanism is discussed based on a transparent fracture replica grouting test. According to the different transport characteristics of the slurry interacting with flowing water, it is divided into the following four areas grout-water balance area, grout loss area, stagnation area and water passage. The grout plugging mode is divided into two categories according to its final diffusion pattern: cross-section type water plugging mode and water-drop plugging mode. The pressure monitoring data of the test verified the two grout plugging modes. The diffusion distance of cis-reverse water derived in this study was in good agreement with the experimental results in grouting early stage. The research results can provide a theoretical basis for grouting engineering design.

Development of Tools for the Direct Measurement of Shear Stress and Shear Strain within a Soil Mass

Abstract This article describes the development of sensing tools designed and applied to the direct measurement of shear stresses and shear strain within a soil mass. The importance in the development of these tools is in their ability to measure shear stresses and shear distortions within soil without any a priori information of the stress and strains applied at the boundaries of the system. These tools may be applied to element testing, testing of physical models, and field applications. The sensors were used in the testing of a sand in a large simple shear apparatus, under both constant height and constant vertical pressure conditions. Testing demonstrated that shear stresses smaller than 0.1 kPa are easily resolved. Shear strains smaller than 10−5 (abs) were reliably measured. Measurement of shear stress and shear distortion within the soil mass allows for direct determination of the shear stiffness of the soil. Shear stiffness measured in this fashion is significantly greater than that determined from the globally measured shear stress and shear strain. The stiffness degradation curve illustrates a constant shear stiffness over the range of 10−5 through 5·10−4.

On the Outflow Boundary Opening Size for Internal Erosion Testing of Widely Graded Sand and Gravel

Abstract Permeameter testing of a widely graded soil to evaluate its potential for internal instability requires the opening size of the outflow boundary to allow unstable finer fraction particles to pass while retaining the stable coarser fraction. Results from a parametric study, on three widely graded soils and five outflow boundaries, yielded paired-data for opening size Om and d85,e of eroded soil mass passing through the outflow boundary. Gradation shape analysis established d85′ of the finer fraction of each soil used in testing. An opening size ratio 5 ≤ Om/d85′ ≤ 10 correlates with a grain size ratio 1 ≤ d85,e/d85′ ≤ 2 and thus an eroded soil mass believed representative of the finer fraction of the widely graded soil. The novel Om/d85′ criterion for sizing the outflow boundary in permeameter testing is found consistent with an alternate criterion using concepts of base-filter incompatibility.

Investigating the Influence of Lemon Grass Root on Soil Stability and Slope Erosion: A Case Study in the Nilgiris District

This study investigates the significant impact of lemongrass root on stabilizing the soil in the hilly slopes of Nilgiris. Lemongrass provides hydrological and mechanical support to the soil mass and also helps enhance the shear strength. The crop is grown as a support against sliding since its roots contribute to slope stability. However, the plant’s usage in the soil stabilization process is still in early stage. This work was conducted to ascertain the utilization of Indian lemongrass plant, which is capable of enhancing the mechanical strength, which was studied using a pull-out resistance equipment. As a means of reducing the cost of field experiments and labour involved, a simulation study was undertaken with the help of Geostudio to analyse the root topology. Even though it is a preliminary study with numerous boundary conditions, the results are promising. The total shear strength and safety factor of the test soil increased when lemongrass was used.

Freeze-thaw effects on pore structure of clay by 3D X-ray computed tomography and mercury intrusion porosimetry

Thaw settlement of soils is a comprehensive reflection of multiscale pore changes induced by freeze-thaw (F-T). In this study, three-dimensional (3D) X-ray computed tomography (CT) tests were utilized to investigate alterations in the macropore and mesopore structures, while mercury intrusion porosimetry (MIP) tests were used to examine the micropore structure in clay due to F-T influenced by different freezing temperatures without water supply. The maximum increase in CT transverse-sectional porosity after F-T can be used to identify where ice lenses formed most abundantly in the clay after thawing, and the diameter and horizontal orientation of the macropores exhibit the most significant increase after thawing. As the freezing temperature decreases, the location becomes farther from the cold end. Macropores are significantly more affected by F-T compared to mesopores, and changes in macropore porosity and diameter can be attributed to moisture migration and freezing shrinkage, with lower freezing temperatures amplifying the influence of freezing shrinkage and weakening the impact of moisture migration. Considering the small size of samples, the MIP porosity was defined to analyze the effects of F-T on the micropores. Compared to the CT volumeratic porosity, the influence of F-T on micropore porosity is less significant. As the freezing temperature decreases, the changes in micropore diameter become smaller. Overall, the lower the freezing temperature, the smaller the changes in macropores, mesopores and micropores. Lastly, a method is proposed for predicting the mass porosity based on the CT volumetric porosity and MIP porosity. This study demonstrates that changes in soil mass porosity reflect a comprehensive representation of multiscale pore variations and provides important theoretical support for thaw settlement control in artificial freezing engineering.

Numerical modelling of the pit wall stability while optimizing its boundaries to ensure the ore mining completeness

Purpose is to assess changes in the stress-strain state of walls along the whole periphery of a super-deep open pit while optimizing its current and final boundaries for the complete ore excavation. Methods. Finite element 3D analysis of stress-strain state (SSS) of the soil and rock mass relies upon the models varying in their scales. Macrolevel model includes the full pit helping perform initial evaluation of its stability depending upon changes in the general wall slope along the pit periphery. Then, the macromodel is separated into sectoral models with smaller scales oriented radially in such a way to include potentially unstable wall areas. The sectoral models make it possible to show the complex bench line in more detail after the peripheries were optimized in terms of economic factor and simulate layered structure of the rock mass. Elastoplastic model of the medium as well as Mohr-Coulomb strength criterion has been implemented using RS3 (Rocscience) program codes. Findings. An indicator of wall strength (safety factor) distribution along the pit periphery has been identified; potential sliding surfaces within each of the separated open pit sectors have been localized based upon the shear strength reduction (SSR) procedure. Influence by the general wall slope as well as by the indicator of the ore excavation completeness on the stripping ratio has been demonstrated. Originality. For the first time, two-level modelling has shown difference in a safety factor depending upon a model scale and a reflection degree of the soil-rock mass structure. In the context of the actual mining and geological conditions of Kacharsky open pit, changes in the safety factor along the pit periphery have been identified depending on the general slope of the wall. Practical implications. Based upon the pit wall stability along the whole periphery, the possibility has been substantiated to optimize its design boundaries for the excavation of those amenable ore reserves, occurred near them, inclusive of ore, occurring in a bottom, which mining is impossible due to inaccessibility.

Interpretation of the data of modern methods of field soil research

This study examines modern in-situ testing methods for soils; it investigates the impact of interpreting these methods on the calculated strength and deformation parameters of soils and compares them with tabulated values according to the DSTU (Standard of Ukraine). In today's world, there is an urgent need for accurate and prompt soil investigations, which are crucial for design and construction. Although laboratory methods are reliable, they often require significant time and resources. The advantage of in-situ methods lies in the fact that testing is performed directly in the soil mass, meaning that the results are not influenced by the transportation and preparation of samples. Conducting tests directly in the soil massif allows for the acquisition of information about soil characteristics and their classification, providing data on soil stratification. This publication reviews modern methods of in-situ soil investigations, specifically CPTu (Cone Penetration Test) and DMT (Dilatometer Test) [1, 2]. These methods are widely used in Europe, while in Ukraine, they are relatively new and are just beginning to gain popularity. Therefore, it is relevant to compare these methods with the tabulated values provided in Ukrainian reference guides. The deformation and stress values were compared using three calculation models based on CPTu, DMT, and DSTU data. A comparative analysis of the foundation slab deformations was conducted using models with elastic and elastic-plastic model. For this purpose, a foundation slab was designed, and a finite element model of the building was developed, examining the foundation on a soil massif with inclined stratification, using both elastic and elastic-plastic soil models.