Soil Mechanics Method Research Articles

Explicit consideration of geomaterial uncertainties in the load resistance factor design of piles driven into rock-based intermediate geomaterials

The study presents a method for estimating the end bearing of piles driven into rock-based intermediate geomaterials (IGMs). Existing design methods, rooted in soil mechanics, often fall short when applied to IGMs. Moreover, the geomaterial (geological and ground properties) uncertainties are neglected and the piles are designed based on subsurface information from distant boreholes. To address this gap, the study introduces an approach that explicitly considers geomaterial uncertainties by combining empirical models and geostatistical simulation to predict end bearing. Using data from 87 piles driven into various rock-based IGMs with dynamic load testing as the construction control technique, this study introduces the Proposed Design Method (PDM) for the prediction of end bearing. PDM is compared to the Current Design Method (CDM), which is based on traditional soil-mechanics methods. Predictions from these methods are subsequently evaluated against the measured end bearings. The results demonstrate that while the PDM yields comparable predictions to the CDM, it offers a more robust consideration of geomaterial uncertainties. The PDM leads to an approximate 13.60% to 19.35% increase in uncertainties compared to CDM across various IGMs. These findings advance the understanding of pile behavior in the presence of geomaterial uncertainties and inherent variability.

Расчет коэффициента сцепления колесного движителя лесной машины с почвогрунтом

The issues of operational and ecological efficiency of wheeled and tracked forest machines have been addressed within the framework of the direction, and previously a separate scientific specialty “Technology and machines of logging and forestry” for a long time now. This direction originated from the works of specialists in the field of agricultural mechanization, who studied the interrelationships in the “mover-soil-harvest” system in detail. Both in agricultural and logging production, when considering the interaction of forest machine movers with the driving surface, the methods of soil mechanics were and are widely used. However, forest soils are a much more complicated environment for theoretical and experimental study, as they have a pronounced layered structure, including organic and inorganic components, and, moreover, are penetrated by the root system of woody and shrubby vegetation. At present, wheeled forest machines of various traction classes dominate in logging production and forestry, which is due to their versatility, high operating speeds, the ability to move between harvesting areas on their own, including moving on public roads. Despite the considerable amount of theoretical and experimental research carried out by domestic and foreign scientists in the field of interaction of wheeled machines with forest soils, the issues of interrelation between the pitch of the ground hooks and the coupling of the mover with the soil have remained poorly worked out so far. This is due, first of all, to the fact that the evaluation of the machine’s passability by traction is given after evaluating the indicators of rutting and resistance to movement. This article is aimed at the theoretical solution of this issue, at the development of the approach to the theoretical assessment of the coefficient of adhesion of the wheeled mover of a forest machine with a soil. For citation: Khitrov E.G., Dolzhikov I.S., Dmitriev A.S., Kalyashov V.A., Grigorev I.V., Grigoreva O.I. Calculation of the Coefficient of Adhesion of the Forest Machine Wheeled Mover with Soil. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 126–134. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-126-134

МОДЕЛИРОВАНИЕ ПРОЦЕССА ДЕФОРМИРОВАНИЯ И ДВИЖЕНИЯ ПОЧВЫ В ЗОНЕ ВОЗДЕЙСТВИЯ ГЛУБОКОРЫХЛИТЕЛЯ

Analysis of available literature shows that nowadays an advanced scheme of the technological process and new designs of operating elements of the subsoiler working in conditions of deblocked cutting has been developed. The aim is to improve the quality and to reduce the energy consumption by machines and equipment during deep tillage. However, at present, the theory of vibrations and strength loading of the units of subsoiler, when its operating elements interact with soil, is not sufficiently developed. This paper highlights the issues regarding the modeling of soil during interaction with operating elements of a subsoiler. Based on the use of the Rakhmatulin model of a compressible plastic medium and the Ilyushin «flat cross-section hypotheses», the equation of the soil motion is formulated, and the dynamic phenomena occurring in the soil and subsoiler elements under variable traction are described. The calculation results are obtained in the Maple-8 programming environment using the methods of solid mechanics and soil mechanics.

Improvement of the Mechanical Characteristics of Soil Contaminated with Lubricant Oil – Cal Mix

The demographic and technological evolutions are confronted by geo-environmental problems. When chemicals or contaminants are introduced into the soil, they affect the soil properties such as the grain size curves, the structure, compressibility and stress-strain behaviour. However, the classical soil mechanics models and methods to incorporate the effects of contaminants have not yet been developed. In this study the proposed analysis of geotechnical structure involving effect of chemicals contaminants such as a wasted lubricate oil with lime on the main factors affecting the behaviour of a compacted soil mass and the analysis of a granite residual soil involving effect of the moisture on the compressibility and shear stress behaviour. These concepts can improve the use of these kinds of soils in geotechnical engineering works.

Analysis and Finite Element Modelling of Water Flow in Concrete

Due to the construction of underground structures and hazardous waste storages, understanding and modelling of seepage in concrete has become an important issue in life-span analyses. The theories and calculation methods of unsaturated soil mechanics provide an opportunity to analyze water flow in other types of porous media (e.g. concrete) as well. This study deals with the determination of the permeability for unsaturated and saturated concrete and modelling the water flow in concrete. The direct measurement of the saturated permeability, the preparation of the drying water retention curve and determination of the depth of penetration of water under pressure are involved in the series of tests. For the fitting method of the experimental water retention curves were used Fredlund and Xing (1994) and van Genuchten (1980) model. The theory of lateral shift was applied to estimate the wetting water retention curve from the drying WRC. Thus, we could calculate the unsaturated permeability functions with Fredlund et al. (1994) and van Genuchten (1980) model. The finite element modelling of the standard test for watertightness were performed with Midas GTS using the measured and calculated unsaturated property functions.

THE IMPORTANCE OF GEOLOGICAL AND HYDROGEOLOGICAL KNOWLEDGE IN JUSTIFYING PORE PRESSURE PREDICTION: THE CASE STUDY OF THE PECIKO FIELD, LOWER KUTAI BASIN

One significant factor affecting pore pressure prediction is choosing a method of calculation. If we choose the inappropriate method, the result may not refl ect not only pore pressure condition in an area, but also geological processes operating in the whole basin. In this research, two methods are applied to wireline-based pore pressure calculation in the Peciko Field: the Eaton Method and the Soil Mechanics Method. The results of the calculation show a signifi cant difference between these methods. The Eaton Method resulted in reservoir-shale pressure discrepancy (by over-predicting the reservoir pressure) at shallower depth, and reservoir-shale pressure equilibrium at depth. On the contrary, the Soil Mechanics Method resulted in reservoir-shale pressure equilibrium at shallower depth and an under-predicting at depth. It seems that, in terms of processes operating in this fi eld which affect pore pressure regimes, i.e. lateral reservoir drainage and rapid mud-dominated deltaic sedimentation, the result of the Eaton Method is more plausible than that of the Soil Mechanics Method. This research also reveals an important inference: if there is a pressure discrepancy, then it is likely that a hydrodynamic condition is present.

Analysis on the influence of heavy rainfall on slope stability

A total of 200 rainfall models were constructed with the slope ratio, rainfall intensity and rainfall duration as the variables for the stable state changes of the loess slope under rainfall conditions. Based on the Fredlund theory combined with the finite element numerical simulation software and the soil mechanics method, the changes of the volume water content and pore water pressure of the slope slope with the rain intensity and the rainfall time were analyzed, and the limit equilibrium theory was obtained. The results show that the rainfall time of the lower slope is different in different rainfall intensity. In the case of slope gradient, the corresponding stability coefficient will decrease with the increase of rain intensity. With the increase of rainfall, the contours of the volume water content and pore water pressure of the slope shoulder and slope foot are becoming more and more intensive.

Ecological safety of buildings depending on the inaccuracies of engineering investigations

The ecological safety of buildings and structures built on deformable soils depends largely on the settlement calculation. A classic example of unaccounted influence of differential settlement is the Leaning Tower of Pisa. Its analogues are numerous among the monuments of Russian architecture. The issue of modern builders to exclude the repetition of defects of old masters, who did not have calculating methods of soil mechanics. The accuracy of modern calculations largely depends on the accuracy of engineering investigations’ materials. In the overall assessment of the system's work, the building-base is currently making a large inaccuracy in the incompleteness of survey information, especially definition the location of geological boundaries directly under the foundation. Two examples show the dependency of the geological soil profile inaccuracy on the distance between the wells and it gives a quantitative assessment of the relationship between the magnitude of the inaccuracy and the distance between the drilling wells of geologists. The numerical modeling method shows the influence of such an investigation inaccuracy on the result of the settlement calculation.

Design and development of a new transformable wheel used in amphibious all-terrain vehicles (A-ATV)

Conventional ground-wheeled vehicles usually have poor trafficability, low efficiency, a large amount of energy consumption and possible failure when driving on soft terrain. To solve this problem, this paper presents a new design of transformable wheels for use in an amphibious all-terrain vehicle. The wheel has two extreme working statuses: unfolded walking-wheel and folded rigid wheel. Furthermore, the kinematic characteristics of the transformable wheel were studied using a kinematic method. When the wheel is unfolded at walking-wheel status, the displacement, velocity and acceleration of the wheel with different slip rates were analyzed. The stress condition is studied by using a classic soil mechanics method when the transformable wheel is driven on soft terrain. The relationship among wheel traction, wheel parameters and soil deformation under the stress were obtained. The results show that both the wheel traction and trafficability can be improved by using the proposed transformable wheel. Finally, a finite element model is established based on the vehicle terramechanics, and the interaction result between the transformable wheel and elastic–plastic soil is simulated when the transformable wheel is driven at different unfold angles. The simulation results are consistent with the theoretical analysis, which verifies the applicability and effectiveness of the transformable wheel developed in this paper.

DETERMINATION OF BUILDINGS BASIS SUBSIDENCE FOR SOIL COMPRESSION INDICATOR

Purpose. To improve the methodology for determining the soil base settlements from the foundation pressure on the parameters of compressibility compressible soil depth strata. Methodology. Laboratory methods for determining the physical and deformation properties of soils; soil mechanics methods; subsidence calculation based on the foundation of layer summation method. Findings. Comparative calculations settling foundations by summing layered methods for using DBN V.2.1-10-2009 deformation modulus of soil and PoltNTU method by using soil compressibility index to improve soil subsidence prediction foundations of buildings. Increased accuracy of forecasting methods of settling base building foundations by using soil compressibility index and the effect of pressure on the deformation parameters of soil and its porosity changes the depth of compressible strata. The calculation results by an improved and normative techniques compared with the data of field observations. Subsidence of foundations bases defined by this index, to 27 % higher than calculated by the soil deformation modulus Originality. Increased accuracy of prediction methods of settling base building foundations by using soil compressibility index and the effect of pressure on the deformation parameters of soil depth compressible strata. Practical value. Increased reliability prediction of subsidence soil base building foundations.

Research on Cracks Zone of Clay Aquiclude in Overburden

The mining induced cracks in aquiclude are major factor of water resisting property and mining safety under water. The aquiclude is composed by loess layer and red clay layer in Yushuwan coal mine. The water reaction property of clay and loess of aquiclude is tested by soil mechanics method. The permeability coefficient of loess will be 0.856 m/d and clay will be 0.434 m/d in Yushuwan mining condition. The dilatability coefficient of loess is 16.1% and the clay is 14.6%. Through physical solid-liquid simulation with whole stress-stain similarity for Yushuwan shallow coal seam mining, the distribution of “downward crack zone” and “upward crack zone” is found to be the major factors of aquiclude stability and the “downward crack” is the main channel of the subsurface ground water flowing down. Furthermore, the downward crack closing in wet clay is revealed and the closing length is about 30% of the downward crack length. The expanding of clay and loess with water are principal factors of downward crack closing. This work will provide the theoretical base for aquiclude stability research.

Simple Tests for the Design Parameters and Sinkage Algorithm for Eco-bags Slope

The slope surface protective structure of eco-bags has a great difference with the conventional ones, mainly because the eco-bags slope is a flexible structure, fillers may mostly be the soils with large plastic deformation, and therefore they have some compressibility. So far, there has not been an effective algorithm for its structural sink or stability. In this paper, based on the simple onsite tests for an actual project, a practical algorithm for the sinkage amount of slope eco-bags is proposed. The algorithm and relevant calculation parameters can be obtained by simple onsite tests and the methods of soil mechanics. By results from the tests, the soils with the proposed percentage of filling materials and compaction process can be directly used in engineering practice. The calculation process of the algorithm is simple, and it has been verified by some practical projects. Thus, its accuracy is satisfactory.

Research on downward crack closing of clay aquiclude in shallow coal seam safety mining

The water resisting property of aquiclude is the key factor of water conservation and safety mining, and the mining induced cracks in aquiclude is major factor of water resisting property. The aquiclude is composed by loess layer and red clay layer in Yushuwan Coal Mine, and the water reaction property of clay and loess of aquiclude was tested by soil mechanics method. The permeability coefficient of the loess is 0.856 m/d and the clay is 0.434 m/d. The dilatability coefficient of the loess is 16.1% and the clay is 14.6%. Through physical solid-liquid simulation with whole stress-stain similarity, the distribution of “downward crack zone” and “upward crack zone” was found to be the major factor of aquiclude stability. The downward crack closing length is about 30% of the downward crack length. The expanding of clay and loess with water are principal factors of downward crack closing. At last, the mechanical model of downward crack closing was constructed, and the criterion of crack closing was put forward at all. This work will provides the theoretical base for aquiclude stability research and safety mining in shallow seam.

Settlement Analysis of Municipal Solid Waste Landfill

In conventional soil mechanics method, the soil particle is known as rigid and its size remains unchanged during a compression. With regard to waste landfill, however, the degradation can decrease the volume of solid particle, produce new gases and liquids. Settlement character, excessive settlement and differential settlement of waste landfill might lead to all kinds of pipelines rupture, and then percolate cannot be expelled and result in rising ground water level. This will threaten seriously the stability of the landfill. It is fundamental to the landfill recycle to calculate the stability of settlement after closure of landfill. Based on the landfill site engineering in Langfang of North China, this article explores a new computing method of the landfill settlement with layering filling and organic matter degradation. Different factors influences on settlement are analyzed by the computer numerical simulation to offer evidence to the landfill recycle.

How to calculate the effect of soil conditions on tractive performance

The paper presents an analysis and quantitative evaluation of the effect of soil conditions on tractive performance of off-road wheeled and tracked vehicles. The results of this study indicated that to accurately calculate the tractive performance of a vehicle in a given soil condition, soil properties and parameters and their changes as functions of soil moisture content and density should be taken into account. An effective Tractive Performance Analytical (TPA) model which takes into consideration the effect of soil conditions on tractive performance of the vehicles is developed. The TPA model uses invariant soil parameters that can be given or measured before the calculations by routine methods of classical soil mechanics. Soil parameters can also be obtained by recommended empirical equations using four physical soil parameters measured in the field with hand held instruments without time consuming and costly plate or vehicle tests. The model was validated in different soil conditions and compared with other models used in terramechanics for tractive performance predictions. The paper includes also an analysis of capabilities and limitations of the observed models.

LSA model for sinkage predictions

The paper presents a Load–Sinkage Analytical (LSA) model, its validation and comparison with other models used in Terramechanics. The LSA model predicts sinkage and penetration force as functions of soil parameters and plates (or traction devices) shape and dimensions. This model uses invariant soil parameters that can be given or measured before the calculations by routine methods of classical soil mechanics. Soil parameters can also be obtained by recommended empirical equations using four physical soil parameters measured in the field with hand held instruments without time consuming and costly plate tests. The paper includes also an analysis of capabilities and limitations of the observed models.

Abstract: A Neural Network and Soil Mechanics Method for Shale Porosity and Pore Fluid Pressure Estimation 

Abstract: A Neural Network and Soil Mechanics Method for Shale Porosity and Pore Fluid Pressure Estimation 

Fluid Flow and Sand Production in Heavy-Oil Reservoirs Under Solution-Gas Drive

Summary The production of heavy oil in Canada has led to a number of anomalous results, most of which have been excused as high-permeability channels resulting from sand production. The methods of soil mechanics predict gross formation failure resulting from high fluid compressibility, small cohesion, and high viscosity. Gross failure results in excellent productivity but reduced in-situ stress (and fracture stress). Solution-gas drive in these reservoirs involves simultaneous-mixture flow of gas as very tiny bubbles entrained in heavy oil. Stress, geometry, and permeability alteration resulting from matrix deformation combined with peculiar pressure-dependent multiphase-flow properties result in a new model of reservoir performance. A field observation of stress modification is discussed, as are the contributions of the four components discussed previously to the observed phenomena.

The sunken lanes of Southern England: Engineering geological considerations

Abstract This paper examines the geological, geotechnical and environmental planning problems of the sunken lanes, or hollow ways, of Southern England. Sunken lanes are generally ascribed to the downcutting action of wheeled traffic on the formerly un-made road, augmenting and accelerating the natural processes of weathering and erosion. The road may be at least several metres below general ground level with a cutting slope in the natural strata and which may be wholly, or partly, vegetated. Sunken lanes must have evolved before road surfacing but the banks are still subject to degradation and although the rate is extremely slow, failure by spalling, debris-sliding or debris-flow may occur. From a site investigation point of view they are difficult to investigate geologically because of a variable extent of weathered mantle and because trial pitting is usually impractical. The materials of the bank can range from loose sand of the weathered mantle, weakly locked or locked sands and harder, cemented rock bands or masses. In most cases, stability cannot be quantified by traditional soil or rock mechanics methods. Where failure of the bank occurs, the Highway Authority may have the problem of assessing stability from engineering geological considerations. The question posed in such cases, is whether the failure represents an isolated occurrence or will it mean an accelerating rate of degradation with further, more frequent and/or larger failures. Since sunken lanes are usually narrow and winding, the fallen material becomes a traffic hazard and a decision may be made that engineering measures are required. These could include re-grading, retaining walls, revetting, gabions or protection by nylon or steel mesh. Sunken lanes are an attractive feature of the landscape, providing scenic variety, a window on the solid geology and a reminder of the past. It would be a loss were all potentially unstable cuttings 'engineered' to provide a safe but purely artificial road bank. This is a problem for environmental planners: to what extent can some hazard be accepted in the interests of conserving a very characteristic feature in the landscape?

On the dynamics of scree slopes

On the Dynamics of Scree Slopes It is shown that the following dynamical phenomena occur on a scree slope: Collapse because of lack of stability, rapid slides of debris material, slow sliding of large blocks, jumping and rolling of large stones, and particle-separation due to a sieving effect. The mechanisms of these phenomena are investigated in detail; it is shown that the stability and the slow sliding of blocks can be explained by soil mechanics methods, the debris slides by the law of dry friction, the rolling of stones by the laws or rolling of spheres, and the sieving effect by a theory analogous to that encountered in the filtration of suspensions through porous media.