Process Of Soil Deformation Research Articles

Peculiarities of using the hypothesis of S.O. Kulon for soil dispersed sediments

The publication is devoted to the outstanding French scientist Charles Auguste Coulomb, who 250 years ago (1773) proposed a hypothesis that relates tangential and normal stresses through the angle of internal friction of soils. This hypothesis provides reliable results while maintaining Hooke's law. Beyond this law, it is necessary to take into account the property of the soil medium, namely the change in volume during shearing or displacement of soils, which requires the introduction of additional dilatancy parameters.
 It is known that there are two types of friction in nature: sliding and rolling friction. At certain values of deformation in the soil medium, sliding friction, which is characterised by the traditional value of the internal friction angle, initially appears in certain zones of the soil medium at low deformations. Further increase in deformation causes rolling friction, which is characterised by a different value of the internal friction angle, almost one third less than the traditional value of the internal friction angle of the soil. This fact must be taken into account when performing numerical modelling of a dispersed soil medium from the beginning of loading to its failure. In this publication, we discuss the methodology for finding the parameters of the dilatancy theory to reveal the elastic-plastic deformation of cohesionless soils based on experimental results. Recommendations are given on the use of the Coulomb hypothesis in engineering calculations and on the relationship between tangential and normal stresses through the angle of internal friction of soils. For a correct description of the nonlinear process of soil deformation, it is necessary to use the parameters of the dilatancy theory, which can be investigated on an axisymmetric shear tester.
 The results of tests of sand of medium size, medium density, low-moisture, homogeneous on several devices showed that the values of the angle of internal friction of soils differ depending on the design of the device. This fact is recommended to be taken into account when designing geotechnical facilities.

Influence of Stump-Root System of Trees on Rut Formation During Forwarder Operation on Peat Soils

To explain the soil deformation processes under the influence of logging machines, average values of various indicators are often used. One of these indicators is the rut depth formed during tractor passages. The average values do not fully describe the consequences of passages on the skidding trails, for example, the rut depth varies along the track. This variability includes both random and regular components. The stump-root systems of trees located on the skidding trail and along its border act as a factor that introduces a pattern. To determine the degree of influence of stumps on 8 sections of skidding trails with the length of 25 and 50 m, located on peat soils (the average mass fraction of water is 82.3%), the rut depth was measured at intervals of 0.5 m and the locations of stumps were noted. The resulting arrays of vertical marks represent the microprofiles of the experimental sections. Measurements were taken after 2 harvester passages and 2 forwarder passages. The stumps were divided into two groups: located inside the tractor track and outside it. Statistical processing of the data showed a wide spread of the rut dimensions in each array. Average values at the sections (standard deviations) in cm were: 21.6(17.7); 30.6(21.6); 37.7(22.7); 46(20.3); 36.4(15.0); 36(15.4); 30.6(21.0); 34(21.0). The autocorrelation functions, constructed for the series of values, showed surges with moderate correlation coefficients on the lags where stumps were noted. An increase in stumps per a length unit of the skidding trail shows an increase in the number of such surges. A decrease in the rut dimensions, in relation to the places where the influence of the roots was absent, averaged: in points 0.5 m away from the stump – 44% (22.6); 1 m away – 32% (20.4); 1.5 m away – 22% (14.2). The spatial influence factor of the roots explains 21% of the variability of the rut dimensions along the skidding trail. The factor of the stump location relative to the track is 19%. The combined influence of these factors is 25%. Further identification of regularities in the rut formation processes is associated both with the continuation of studies of the root system influence, but with the inclusion of factors of the stump size and variety, and with the study of the variability of the soil physical properties along the skidding trails, analysing how this is found in the microprofile structure.

Temporal evolution of soil deformations around monopile foundations subjected to cyclic lateral loading

Cyclic lateral loading on a monopile in windfarms has been found to cause bed subsidence and convective motions of sediment particles around its foundations. These soil deformations may affect the bearing capacity of the foundation and safety of the structure. This paper presents a 2-dimensional (2D) experimental study on the temporal evolution of bed subsidence and sediment convective-area around vibrating monopiles. The experiments were carried out in a sandbox with a transparent front wall, through which the temporal development of soil deformations around the vibrating monopile can be observed and recorded by using a high definition web camera. The characteristics of the soil subsidence and convective cells are examined with the recorded images, and the influence of the applied force and cyclic loading frequency on the soil deformation process are discussed. The experimental data show that increasing either the force or loading frequency can increase both the temporal development rates and the final size of the subsided bed and convective cells. Empirical equations for depicting the temporal evolution of the subsidence (depth and width) around monopile foundations are proposed.

Graph-analytical optimization of the transverse vertical cross-section of a contact zone between soil and an elastic wheeled mover

The intensification of agricultural production under modern conditions implies the use of super-powerful mobile technical means, which leads to an increase in the levels of technogenic impact on soil and, consequently, deteriorates its fertility. Therefore, the most acute issue related to current agricultural production is aimed at resolving the task on improving the operational indicators of wheeled running systems of mobile technical means. This necessitates an analytical study into the processes of soil deformation under the elastic motors of mobile wheeled agricultural machinery. We have proposed a procedure of the graph-analytical step-by-step modeling of the process of soil deformation under pneumatic tires of mobile agricultural equipment taking into consideration the changing shape of an elastic tire sheath. Using appropriate graphic models makes it possible to explore, in stages, the process of soil compaction inside the profile of the track it formed. It has been found that in the contact area «deformed soil – the surface of an elastic wheeled mover of the mobile vehicle» the highest level of compaction is observed in the soil layer, which is directly in contact with the elastic mover. The depth of the recompacted soil layer on the «track bottom» depends on the dimensions of a tire of the wheeled mover and does not exceed the value of 0.075 width of the tire. The highest soil compaction level is observed in the area directly adjacent to the gauge. It has been established that the most dangerous design of a pneumatic tire, in terms of soil overcompaction in the track, is the shape of an elastic tire sheath that is described by the curve of the Cassini oval with four points of inflection. We have outlined distinctive features of recommendations to determine the operational values of tire working pressure depending on specific physical-mechanical and agro-technological properties of soil and the character of performed technological operations

Analysis of Penetration Depth of Pipeline on Cohesive Soil Seabed

This paper conducts laboratory tests to investigate detailedly the soil deformation law around the pipeline and its penetration depth under self-gravity. The seabed model is prepared by consolidating saturated soil using vacuum pressure technology, and the pipeline models are specifically designed to possess different radii. Based on the experimental results and digital images, the soil deformation process is analyzed and summarized, a kinematic admissible velocity field is given and an upper bound solution of pipeline penetration depth and soil reaction force is derived and proposed in this paper. In order to verify the accuracy of the upper bound solution deduced in this paper, a comparison is made among some published results and the solution suggested in this paper, the comparison results confirm that the upper bound solution and the soil failure mode are reasonable. Finally two empirical formulas are given in this paper to estimate the soil reaction force of seabed and the penetration depth of pipeline. The empirical formulas are in agreement with the upper bound solution derived in this paper, and the conclusion of this paper could provide some theoretical reference for the further study of the interaction between the pipeline and the soil.

ФАКТОРЫ УПРАВЛЕНИЯ КАЧЕСТВОМ И ЭНЕРГОЗАТРАТАМИ ПРИ РЫХЛЕНИИ ПОЧВ

The process of soil deformation is a trajectory in a multidimensional space of principal stresses and principal deformations, as well as time, that is, the speed of application of deformer forces. Consequently, it is possible to achieve its destruction at various energy costs. With more rational technologies, volume deformations are minimal, and vice versa. The destruction of the soil massif should be along lines and planes characterized by the least strength. More preferred are working elements, the elements of which are executed in such a way that the sizes of the compaction zone inevitably arising as a result of their action on the soil layer are minimized. The dynamics of this process is influenced by the shape of the loading curve, the after-effect speed. The evaluation of efficiency with continuous oscillation by constant amplitude and frequency did not reveal the maximum of the energy efficiency. A promising direction is the additional oscillation of the working organ by single impulses. The construction of a soil-working working organ, self-adapting to changing operating conditions, is proposed. On the basis of the equation of motion, factors influencing the quality and energy costs of the loosening of the soil are established. Design changes are proposed to improve efficiency.

A Photographic Method for Measuring Soil Deformations during Internal Erosion under Triaxial Stress Conditions

Abstract Internal erosion involves the migration of soil particles under seepage flow and is a primary cause of dam failure and distress. With the loss of soil particles, the remaining soil grains will rearrange, resulting in soil deformations and significant settlement. In this research, a photographic method was developed to measure the soil deformations caused by internal erosion on a modified triaxial apparatus. Photos were taken by a high-resolution camera at a certain time interval. By comparing image data between any two snapshots, the process of soil deformation can be obtained. In the experiments, the soil specimen experienced marked deformations during internal erosion. Heterogeneous soil deformations also developed across the specimen because of the nonuniformity of the soil pores and the nonuniform migration of fine particles. Both the global and local soil deformations during the whole internal erosion process were obtained using the photographic method. The maximum lateral deformation occurred at the middle part of the soil specimen, whereas the soil deformations along the vertical direction were relatively uniform.

Modeling of traction-coupling properties of wheel propulsor

In conditions of operation of aggregates on soils with low bearing capacity, the main performance indicators of their operation are determined by the properties of retaining the functional qualities of the propulsor. Therefore, the parameters of the anti-skid device can not be calculated by only one criterion. The equipment of propellers with anti-skid devices, which allow to reduce the compaction effect of the propulsion device on the soil, seems to be a rational solution to the problem of increasing traction and coupling properties of the driving wheels. The mathematical model is based on the study of the interaction of the driving wheel with anti-skid devices and a deformable bearing surface, which takes into account the wheel diameter, skid coefficient, the parameters of the anti-skid device, the physical and mechanical properties of the soil. As a basic mathematical model that determines the dependence of the coupling properties on the wheel parameters, the model obtained as a result of integration and reflecting the process of soil deformation from the shear stress is adopted. The total value of the resistance forces will determine the force of the hitch pressure on the horizontal soil layers, and the value of its deformation is the degree of wheel slippage. When the anti-skid devices interact with the soil, the traction capacity of the wheel is composed of shear forces, soil shear and soil deformation forces with detachable hooks. As a result of the interaction of the hook with the soil, the latter presses against the walls of the hook with the force equal to the sum of the hook load and the resistance to movement. During operation, the linear dimensions of the hook will decrease, which is not taken into account by the safety factor. Abrasive wear of the thickness of the hook is approximately proportional to the work of friction caused by the movement of the hook when inserted into the soil and slipping the wheel.

Dynamic stress measurements and the impact of timber harvesting on physical soil properties

ABSTRACTThe stress impacts of forestry machinery were determined and compared with internal soil strength to evaluate soil stability and identify soil compaction processes. In order to simulate a typical timber harvest, we analysed the soil deformation processes of one harvester (HA; 24 tonnes (Mg)) and one timber hauler (TH; 28 tonnes (Mg)) at three different sites in Germany, on soils derived from loess. The 1st pass was carried out with the HA and the 2nd to 5th passes were carried out with the TH. To determine stress impacts, the major principal stress (σ1) was measured using a stress-state transducer system installed at three different depths (20, 40 and 60 cm). Before and after wheeling, soil samples were taken to determine the precompression stress (PC)—as the fundamental parameter for internal soil strength—and the hydraulic parameters saturated hydraulic conductivity (Ks) and air capacity (AC). The combination of stresses at the various depths and the internal soil strength forms the basis for the proposed quantification of induced soil deformation processes. Soil stability can thus be derived from both parameters, and negative consequences for soil functions can be predicted if the ratio PC/σ1 is <0.8). These changes were quantified by comparing changes in Ks, AC and PC. Results for stress impacts revealed decreasing values of σ1 with increasing soil depth, and maximum values (σ1 > 600 kPa) during the 1st pass with HA. The PC/σ1 ratio described unstable soil conditions for almost all soil horizons, including that at 60 cm. PC was significantly increased in the topsoil after the 1st pass with HA and even more so after the 5th pass with TH, whereas both Ks and AC values decreased. Significant decreases in Ks were determined for almost all measurements at all depths, as well as for AC in topsoil and after the 5th pass with TH at 40 cm soil depth.

Characteristics of Acoustic Emissions from Soil Subjected to Confined Uniaxial Compression

Core IdeasAcoustic emissions (AEs) reveal information on soil deformation processes.We studied AEs during loading–unloading–reloading cycles under confined compression.The number of AE hits reflected well the soil deformation regimes.Soil compression and swelling indices correlate with AE parameters.The Gutenberg–Richter power lawbvalue varied with wet soil yield stress.Application of mechanical stresses to soil results in deformation, microfracturing, particle motion, and liquid reconfiguration that may release measurable amounts of stored elastic energy in the form of acoustic emissions (AEs). This study aimed to systematically study AE characteristics during confined uniaxial compression of soil samples and link various AE parameters to soil deformation regimes. We hypothesized that variations in AE characteristics could offer new insights into the transition between elastic and plastic soil deformation and noninvasively identify the onset of yield stress. We subjected soil samples at known water contents to a loading–unloading–reloading cycle under uniaxial compression using an oedometer coupled with an AE monitoring system. The soil was a sandy loam equilibrated with two initial gravimetric water contents (12 and 25%) and two initial bulk densities (1.3 and 1.55 Mg m−3) for each water content. Observed AE event numbers (hits) and their energy content (E) varied during stress application to soil samples. Close agreement was found between soil yield stress deduced from normalized cumulative AE parameters and measured stress–void ratio curves (precompression stress, σpc) for the dry soil; however, the yield stress deduced from AE parameters was significantly larger than σpcfor the wet soil. Swelling and compression indices were strongly correlated to AE hits andE, respectively. The preliminary results illustrate the potential of monitoring passive AE during load application to characterize soil mechanical parameters (potentially in situ). Nevertheless, additional studies with controlled pore water pressure and a range of soil types would be required to generalize these findings to offer a robust AE‐based method.

A Laboratory Study on the Use of Optical Fibers for Early Detection of Pre-Failure Slope Movements in Shallow Granular Soil Deposits

Although landsliding is the macroscopic effect of slope failure, it is only the final stage of an often time-consuming process of soil deformation. In many cases, slope movement remains extremely slow and undetected for a long time; in other cases, failure is abrupt, preceded by small deformations and followed by rapid, destructive movements. This is the case of slope failure in granular soils of pyroclastic nature, which involve an extensive mountainous area surrounding Mt. Vesuvius in southern Italy. Given that the area around Vesuvius is highly urbanized and densely populated, the detection and interpretation of pre-failure slope deformations are of great importance for risk mitigation. To this aim, Brillouin optical time-domain analysis (BOTDA), a distributed fiber optic sensing technique, may represent an efficient new tool. This paper illustrated the results of laboratory experiments on small-scale slopes instrumented with optical fiber sensors, showing the main features of this technique for early detection of slope failure.

OCR and POP Parameters in Plaxis-based Numerical Analysis of Loaded over Consolidated Soils

The paper discusses deformation of over consolidated soils in Hardening Soil Model in terms of their initial stress state. When carrying out numerical analysis in Plaxis, it has been stated that Hardening Soil Model “remembers” the history of previous loadings. In forming the initial stress state of over consolidated soils with the pre-overburden pressure POP, there occurs the more reliable description of the soil deformation process than with the over consolidation ratio OCR. These findings are valid for odometer conditions and for real geotechnical calculations.

Measuring the Dynamic Soil Response During Repeated Wheeling Using Seismic Methods

Our understanding of soil deformation processes, especially its dynamics, remains limited. This hampers accurate predictions of the impact of soil management practices such as agricultural field traffic on (physical) soil functions. The main objective of this study was to investigate whether seismic measurements could be used to assess the dynamic soil behavior during repeated loading. Moreover, we aimed at linking the velocity of P‐waves, Vp, to traditionally measured soil properties associated with soil compaction, namely bulk density (ρb) and penetrometer resistance. A wheeling experiment was performed with an agricultural tire (60 kN wheel load) on a gleyic Cambisol. We measured Vp using an acoustic (microseismic) device at various depths before, during (i.e., below the tire), and after wheeling. In addition, we measured bulk density and penetrometer resistance before and after wheeling, and simulated the evolution of bulk density due to the wheeling using a soil compaction model. The dynamic soil response during loading–unloading–reloading cycles could be well captured with the seismic method. The measured Vp related to bulk density, and the compaction‐induced increase in Vp correlated with the increase in penetrometer resistance. The seismic measurements seem a promising in situ method for gaining new insights into the dynamics of soil behavior. The method may be especially powerful when combined with traditional measurements and with modeling of soil deformation.

Numerical Simulation of Digging Shovel Operation of Cassava Root

Based on the methods including modified Mohr-Coulomb yield criterion, Lagrange and smoothed particle hydrodynamics (SPH), the digging shovel - stem - root - soil system dynamics simulation model is established by ANSYS/ LS-DYNA. According to the model, the interaction mechanisms among the digging shovel, soil and root are discovered, and the processes of soil shearing and the changing processes of root's stress are analyzed. The mechanisms of shovel's soil loosening are discovered. The process of soil deformation, fracture and loosening and the changing process of root's stress on micro level are studied. The results show that (1) the main reasons for soil loosening in the digging shovel operation are that the soil on the wedge is bended fracture due to being squeezed and uplifted, and that the soil is sheared and broken in the direction of the wedge's normal, and that the soil has no supporting of the blade so that a lot of fractures appear on the soil and is separated by the shovel blade, and that the upper and lower soil can't be closed; (2) when the wedge's extrusion attains a certain value, the links of root and soil will be destroyed; (3) the soil stress value around the wedge is largest, and the soil shearing rupture develops from bottom to top, and the shearing rupture surface occurs in the widest place of shovel blade in the direction of wedge's normal; (4) when the blade's tail points at the root, the root's effective stress is largest and makes the bending deformation of root forward and upward in the meantime, and when the root's effective stress is too large, the root will be broken and the harvest will be lost.

The Model Test about Over-Consolidated Soils’ Stress and Deformation as Water Pressure Increasing

The main compression layer of Xi’an is over-consolidated. Based on the property, the physical model is designed as a steel cylinder which is 2.5m diameter,3m high. The soil layers are inter-bedded with silty clay and medium-fine sand. The consolidation pressure and overburden pressure is 295KPa. The process of soil deformation was simulated as the water recovering by increasing the water pressure in the medium-fine sand layer. Data monitoring test reveal that the deformation of the medium-fine sand layer and the silty clay layer is piecewise consequent，the consolidation will stop when the water pressure surpass a certain threshold value; During this test, the deformation of sand have the consistency with the variation of stresses in the medium-fine sand, but the deformation of the silty clay layer lagged to the variation of stress. The increase of water pressure in medium-fine sand cause compression pressure of others soil layers to increase. Based on the study of this test, we could predict that the land subsidence of Xi’an will not stop unless the confined water pressure surpasses the threshold value. What is more, we can reduce the subsidence through spasmodic pumping without cutback of pumping.

Experimental analysis of dynamic mechanical properties for artificially frozen clay by the split Hopkinson pressure bar

A device for impact compression experiments is the split Hopkinson pressure bar with a refrigerating attemperator. Data for incident and reflected waves are obtained by the measuring technique with strain gauges, and data for transmitted waves are obtained by the measuring technique with semiconductor gauges. Static compression tests of frozen clay are conducted at an identical temperature and different strain rates of 0.001 and 0.01 sec −1 . Dynamic stress-strain curves are obtained at strain rates of 360–1470 sec −1 . The low and high temperatures correspond to high and low strain rates, respectively. It is shown that both the temperature and strain rate affect the frozen soil deformation process. Different dynamic stress-strain curves obtained at the same temperature but different strain rates are found to converge. The test results indicate that frozen soil has both temperature-brittleness and impact-brittleness.

Non-invasive 3D analysis of local soil deformation under mechanical and hydraulic stresses by μCT and digital image correlation

Soil deformation is a perpetual process in the pedosphere where besides physicochemical stresses primarily alternating hydraulic and mechanical stresses continuously re-arrange the configuration of solid particles. In this study we present a local strain analysis and changes in soil structure resulting from hydraulic and mechanical stresses based on X-ray microtomography data. Digital image reconstructions were used to quantify local structural pore space characteristics and local soil deformation by 3D morphological and correlation analysis of grayscale tomograms. Swelling and shrinkage resulted in a complex heterogeneous soil structure which proofed to be very stable when mechanical loads were applied. The mechanism of soil deformation for both structure formation by internal hydraulic stresses and structure degradation by external mechanical stresses were in both cases controlled by pre-existing (micro)-structures. Especially during wetting such structures served as a nucleus for subsequent structure evolution. The results demonstrate the potential of more detailed non-invasive micromechanical analysis of soil deformation processes which could improve the conceptual understanding of the physical behavior of soil systems.

Deformation processes below a plate sinkage test on sandy loam soil: experimental approach

Mathematical models to predict the mode and extent of deformation occurring below sinkage plates are presented in the first part of this paper which encompasses the theoretical approach to the subject. These models are based on previous work by Earl (Earl R. Assessment of the behaviour of field soils during compression. Journal of Agricultural Engineering Research 1997;68:147–57)who developed a procedure to predict the likely mode of deformation using confined compression tests carried out alongside plate sinkage tests. This work suggested that soil behaviour, during increasing compression under a sinkage plate, is governed by three processes; (i) compaction below the plate with constant lateral stress, (ii) compaction with increasing lateral stress, and (iii) displacement and compaction of soil laterally. The aim of this second part to the paper is to observe soil deformation processes occurring below a circular sinkage plate to examine (i) whether the three phases of deformation referred to above occur in practice, and (ii) the accuracy of the models for predicting the soil deformation processes that occur. Tests were carried out on sandy loam soil under controlled conditions in a soil bin. Observations of deformation processes, recorded using long-exposure photography, revealed that during the initial stages of sinkage (a few millimetres), the corresponding disturbance of soil below the plate extended disproportionately further and was cylindrical in form. As sinkage progressed, the deformation process went through a transitional stage before reaching the more widely recognised form of the development of an inverted cone of compacted soil directly below the plate which moved with the plate causing lateral soil movement and compaction. Predictions for a medium density sandy loam were found to be in broad agreement with soil behaviour under a semi-circular sinkage plate observed behind a sheet of tempered glass under controlled conditions in a soil tank.

Behavior of soil under a brief dynamic load

1. The damping coefficients both of cohesive and noncohesive soils practically do not depend on the state of the soils relative to the limit state almost up to loss of strength by the soil specimen. An increase of the initial lateral pressure and dry density of the noncohesive soil as well as a decrease of the moisture content of cohesive soil noticeably reduce the value of the damping coefficients (from 0.6 to 0.05 for noncohesive and from 0.3 to 0.15 for cohesive). The interval of variations of the damping coefficients obtained under conditions of small values of the initial lateral pressure (within 0.1 MPa) and combined stress state leads to the need for an experimental determination of the damping coefficients, at least for similar conditions. 2. The shear moduli for small values of the initial lateral pressure and under conditions of a combined stress state for cohesive soil depend on the level of the initial lateral pressure and for the noncohesive on the change in the moisture content. In the interval of stresses created in the specimen, when the initial lateral pressure does not exceed 0.098 MPa and the average static stress does not exceed 0.3 MPa, the shear moduli are practically proportional to the average stress. 3. Both volumetric strains and distortional strains under a brief dynamic shear load and under conditions of a combined stress state are far less than the strains from an equal static load. In this case, whereas the volumetric strains in shear for noncohesive soil have the character of compacting, for cohesive soils they are always loosening. 4. The description of the process of soil deformation as a result of a brief dynamic load obtained shows the possibility of determining the nonlinear reaction of soil to this load by means of the linear acceleration method, if the system under consideration can be represented as a system with one degree of freedom.

Evaluating Penetration Resistance and Wheel Sinkage Response to Soil Water Suction Changes in a Draining Clay Soil

AbstractTo facilitate the development of subsurface drainage design criteria for the reduction of soil compaction, the relation between the bearing capacity of nearly saturated soil and its water suction(s) is analyzed for a cone penetrating into the soil and for a sinking tractor wheel. Approximate equations are developed, from basic soil mechanic theory, for certain soils under a limited range of suction and loading conditions. The main assumptions are attainment of plastic equilibrium during dynamic loading and independence of the soil deformation process and its shear failure pattern of suction. The penetration resistance‐suction model shows that a linear response to suction changes can be expected, characterized by a modified bearing capacity‐suction factor (Ns) which may be estimated from the mechanical and water properties of the soil. The wheel sinkagesuction model predicts the relative change in wheel rut depth in response to loading (inflation pressure) and suction changes, by means of the same Ns parameter. Tests were conducted in plowed (P1) and unplowed (P0) irrigated plots of a clay soil, utilizing a cone penetrometer and a tractor with differentially loaded and differentially inflated rear wheels. Variations in penetration resistance with suction were successfully predicted, assuming local, intermediate, and general shear failure in the subsoil, and in the plow‐layers of P1 and P0, respectively. The relative change in wheel rut depth with suction was found predictable, provided S &gt; Smin. The transition from S &gt; Smin to S &lt; Smin was characterized by an inversion of sinkage response in P0, and by a transition from vertical to horizontal soil compaction or flow in P1.