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Field measurements of frozen soil creep in the upper 3.0 m of permafrost indicate that creep occurs in both winter and summer. Between 1992 and 1993, the mean rate of creep ranged from 0.44 cm at 1.6 m depth to 0.16 cm at 2.8 m depth but there was extreme variability. Creep parameters n and A, as defined by the power flow law, were calculated from field data. Parameter n ranged between 1.96 and 2.29 and increased with depth, while A decreased with depth. Comparisons of creep rates for different permafrost environments suggest that ground temperature largely controls the magnitude of permafrost creep. Key words : permafrost, creep parameters, Tibet Plateau.

Development trends of the modern city imply a reduction in the number of inhabitants in its centre, and thus the construction of dormitory suburbs on the outskirts of the city. One of the potential areas for the development ofSzczecinis its northern part, i.e. the so-called Warszewo Hills. This area has both latitudinal and meridional extents of about 8 km, and is characterized by complicated engineering-geological conditions. It lies at altitudes ranging from the sea level (OdraRiver) to 130.9 m a.s.l. (Wielecka Góra), and has very varied relief. Its landscape consists of hills and flat plateaux, which are cut by deep small valleys, some of them with streams (e.g. the Warszewiec stream). Geological structure is characterized by the occurrence of glacitectonically disturbed moraine deposits mixed with the Tertiary sands and clays. Taking into account geodynamic processes and their intensity, the wide edge zone of the Warszewo Hills can be divided into three main parts: plateau with the upper edge of slope (area of precipitation infiltration), slope, which is cut by small erosion valleys in places (area of surface water and groundwater flow), slope foot (area of water flow and accumulation of slope deposits). One of the most important tasks of the design-investment process is to take action in such a way as to interfere as little as possible in the natural environment and at the same time to achieve the intended purpose. Predominant occurrence of cohesive deposits in the described area (Oligocene scaled clay mixed with moraine disturbed material) results in a high susceptibility of ground to moisture changes. Strength parameters of stable slopes built of clays considerably decrease under the influence of increasing moisture and thixotropy phenomenon. Then landslide processes are triggered, as well as very slow, hardly noticeable in a short time, soil creep. The complicated arrangement of deposit layers results in spatial variability of groundwater level, and proper design of building foundation is difficult, even in the case of a small, detached house. Too much interference in the landform features (through macro-levelling, construction of streets and routes in the area with steep slopes), the decrease of water retention and increase of surface runoff contribute to an intensification of some geodynamic processes.

The weathered profile over the Posse gold deposit results from the modification of a complete lateritic profile related to the Velhas surface of lower Pleistocene age. Lateritic and postlateritic weathering has affected the distribution of gold in the profile. Mass balance studies show that during postlateritic weathering all levels of the profile have been absolutely enriched in gold and that the gold-bearing overburden has been eroded from the upper part of the profile. Gold enrichment has taken place by chemical and mechanical processes. In the saprolite, chemical reprecipitation of gold by reduction of complexes below the water table has resulted in homogenization of the gold grades and supergene enrichment. Gold is also chemically reprecipitated onto the surfaces of the coarse ferruginous quartz particles, probably by iron adsorption. This process is very important in the stone line, resulting in a strong gold enrichment there. Downward mechanical accumulation of the coarse gold, facilitated by pedogenetic processes, has also contributed to this enrichment. Lateral dispersion is mostly related to soil creep and is more pronounced in the top soil, from where the smaller gold particles have been preferentially eroded. Low gold concentrations in pisoliths suggest that the gold concentration in the ancient iron crust was low. A model is presented to describe the weathering evolution and the mechanisms of gold redistribution in the Posse profile. This is compared to other areas in Western Australia and west Africa. The implications for gold exploration in lateritic terrains are also discussed.

This paper presents a new method proposed for the prediction of long term settlement of very heavy structures based on a numerical interpretation of long term pressuremeter creep tests. The constitutive model used for the modelling of the soil creep is described. The constants of the constitutive model are determined by fitting a simulated curve, given by a simple Finite Element Method, to the results of a long term pressuremeter creep test. The calculation of long term settlement under nuclear power plants, using the soil parameters defined by this method, is presented and compared with the in situ measured values.

A series of numerical experiments on the failure process of homogeneous rock slope has been performed using Boundary Element Method and Displacement Discontinuity Method, and then the effect of initial rock stress on the stability of homogeneous rock slope has been discussed.Firstly, the distribution of tangential stress along the surface of rock slope has been analysed and the condition of fracture initiation has been formulated. The stability factor at the fracture initiation.of rock slope is affected by not only the slope angle and the rock strength but also the initial rock stress. Increasing the ratio of horizontal to vertical stresses at the pre-excavation, the value of the stability factor decreases and the location of fracture changes from the toe of slope to the upper surface.Secondly, failure process of rock slope has been analyzed on the basis of the Fracture Mechanics. It is made clear that the failure process and the failure mode are also affected significantly by the initial stress state as well as the rock strength, the frictional characteristics of the crack surface and the slope angle. Furthermore, it is pointed out that the critical value of the stability factor is rather independent of the initial stress state.

[1] We present analytical solutions for the steady state topographic profile of a soil-mantled hillslope retreating into a level plain in response to a horizontally migrating base level. This model applies to several scenarios that commonly arise in landscapes, including widening valleys, eroding channel banks, and retreating scarps. For a sediment transport law in which sediment flux is linearly proportional to the topographic slope, the steady state profile is exponential, with an e-folding length, L, proportional to the ratio of the sediment transport coefficient to the base level migration speed. For the case in which sediment flux increases nonlinearly with slope, the solution has a similar form that converges to the linear case as L increases. We use a numerical model to explore the effects of different base level geometries and find that the one-dimensional analytical solution is a close approximation for the hillslope profile above an advancing channel tip. We then compare the analytical model with hillslope profiles above the tips of a groundwater sapping channel network in the Florida Panhandle. The model agrees closely with hillslope profiles measured from airborne laser altimetry, and we use a predicted log linear relationship between topographic slope and horizontal distance to estimate L for the measured profiles. Mapping 1/L over channel tips throughout the landscape reveals that adjacent channel networks may be growing at different rates and that south facing slopes experience more efficient hillslope transport.

[1] Past studies of hillslope evolution have typically assumed that soil creep processes are governed by a linear relationship between local hillslope angle and transport distance. The assumption of “linear diffusion” has fallen out of favor because, when coupled with an expression of mass continuity, it yields unrealistic hillslope profiles. As a consequence, a better understanding of the mechanics of sediment transport is needed. Here we report results from a series of flume experiments performed to investigate sediment transport by dry ravel, a common soil creep process in arid and semiarid environments. We find that, at gentle slopes, transport distances follow distributions characteristic of local transport. As gradients steepen, a fraction of the particles begins to exhibit nonlocal transport, and that fraction increases rapidly with slope. A stochastic discrete element model that couples an effective friction term with a shock term reproduces the results from the flume experiments, suggesting that it can be used to explore the nature of particle transport on rough surfaces. The model predicts that exponential distributions of transport distances on gentle slopes evolve into quasi-uniform distributions on steep slopes, and the transition occurs as slopes approach the angle of repose. Our results support previous findings that the angle of repose represents a threshold between friction and inertial regimes. In addition, we propose that the angle of repose represents a fuzzy boundary between local and nonlocal transport.

A parametric study is carried out to investigate the applicability of limit equilibrium method for analyzing reinforced embankment on soft soil in this paper. The effect of vertical spacing of geotextile layers, slope inclination, and tensile strength of PET (Polyester) and PP (Polypropylene) geotextile behavior on reinforced flyash and clay mixed embankment, over a soft clay layer is studied. For present investigation study, a 8 m high embankment with 20 m crest width and slopes of 58°, 64°, 72°, and 78° are considered. Analysis was performed using the GEO5 – slope stability software version 12 after modeling the above standard geometry. Results divulge that use of full length of geotextile covering whole width of embankment can increase factor of safety (F.S) at steeper slope inclination. Also decreasing the slope inclination and vertical spacing of geotextile gives safer designs. From this study it is seen that reinforced embankment with PET geotextile gives economical and safe design, compared to PP geotextile when the creep phenomenon is considered as a governing factor.

The safety of high-speed railway over areas with serious regional land settlement is further concerned by more and more engineers. However, there is few research concerned about the influence on bearing behaviour of pile foundations by regional land settlement in high-speed railway bridge construction at present. This paper presents a new method using the numerical method to simulate underground water level’s annual variations in the situation of continuous pumping based on the limited site measurement data and studying the influence on bridge pile foundations by regional land settlement on that basis, finally obtaining the relationship between regional land settlement and bridge pile foundation settlement. The result shows that increase of land settlement lags behind pumping due to soil creep effect, in early phase the land settlement is mainly affected by the consolidation of soil mass and in late phase affected by creep. The associative relationship of regional land settlement and bridge pile foundation settlement is very obvious which generally expresses as a logarithmic form.

As a result of the scarcity of land for construction, number of projects to construct man-made islands or to expand lands over soft grounds keeps increasing. Consolidation and creep are significant in the soft soil and hence, their long term deformation must be taken into account in engineering design and practice. Soil creep has significant impacts on the stability of the structures constructed on the soft ground. In this paper, a case study of an embankment constructed in stages in north Boston over a thick layer of Boston Blue Clay is numerically investigated in order to consider the effects of the soil creep. The behaviour of the ground is simulated using a finite element program associated with and without soil creep. A parametric study on the soil creep ratio is conducted to evaluate its effects on the predictions of the excess pore water pressure and lateral displacement. It is observed that the increase in the value of creep index causes the increases in both of the horizontal displacements and excess pore water pressures of the ground. In addition, the factor of safety against slope instability decreases with the creep ratio. Thus, the effects of soil creep should be earnestly considered in predicting the ground performance under embankments.

Diverse non-invasive seismic techniques are used to gain a fundamental knowledge of a complex unstable slope in the Italian Central Alps. A recen t detailed geomorphological survey has proved the slope is affected by a deep gravitational deformati on accompanied by superficial landslide phenomena, debris avalanches, soil creep and infrastructure da mages. As the unstable slope directly threatens the popular ski resort of Madesimo, the risk associated to a possible collapse may be very high. Hence new efforts are required to define the geological and p hysical model of the slope, and to comprehend its dynamic and cinematic behavior. Recently, preliminary 2D seismic investigations hav e been carried out at the slope toe, where a supposed sliding surface can be more easily detecte d, the slope is more gentle and a road offers the possibility to bring the seismic equipment close to the survey line. A shotgun and a 72-channel system assembled by combining equipment from two different manufacturers have been used to perform a reflection/refraction survey. P-wave first arrivals have been inverted with the main purpose of delineating the interfaces between weathered and ma ssive rock and the velocity gradients associated with different fracturing degrees of the rock slope . The same dataset has been also processed accordin g to the Multi-channel Analysis of Surface Waves (MASW) methodology. Surface wave analysis has been used to characterize the slope with S-waves, thus p roviding complementary information with respect to the refraction survey, as well as to verify the pre sence of velocity inversions. Reflection data have been processed to better identify the acoustic discontin uities within the slope and to extend the penetrati on depth of the previous seismic techniques. The proce ssing sequence involves basic steps with no multichannel operations to avoid introducing artifa cts in the seismic section. Seismic results have been jointly interpreted with the support of the geological information gathered by superficial surveys.

bryan.mccabe@nuigalway.ieIt is widely accepted that granular (stone) columns can reduce settlement andimprove bearing capacity in soft cohesive soils. The extent to which stone columnsreduce settlement is known as the ‘settlement improvement factor’, and much ofthe research to date has focused on quantifying the improvement factor for pri-mary settlement. However, secondary settlement (or creep) can be significant, ifnot dominant, in soft normally consolidated (especially organic) cohesive soils,and some effort needs to be diverted towards identifying the improvement factor,if any, for secondary settlement. To this end, two-dimensional axisymmetric finiteelement analyses of a unit cell have been carried out using PLAXIS 2D to deriveseparate ‘settlement improvement factors’ for the primary and secondary phasesof settlement. The Soft Soil Creep Model is used to simulate the behavior of thehost soft clay while the stone is modeled using the Hardening Soil Model. Thispreliminary study has shown that the columns result in a significant improvementto primary settlement (in line with predictions using well-known analytical designmethods); whereas the effect on secondary settlement, although positive, appearsto be significantly less.Keywords: Stone columns, Primary consolidation, Secondary settlement (Creep),Settlement improvement factor.

[1] In mountainous terrain, deep‐seated landslides transport large volumes of material on hillslopes, exerting a dominant control on erosion rates and landscape form. Here, we develop a mathematical landscape evolution model to explore interactions between deep‐seated earthflows, soil creep, and gully processes at the drainage basin scale over geomorphically relevant (>10 3 year) timescales. In the model, sediment flux or incision laws for these three geomorphic processes combine to determine the morphology of actively uplifting and eroding steady state topographic profiles. We apply the model to three sites, one in the Gabilan Mesa, California, with no earthflow activity, and two along the Eel River, California, with different lithologies and varying levels of historic earthflow activity. Representative topographic profiles from these sites are consistent with model predictions in which the magnitude of a dimensionless earthflow number, based on a non‐Newtonian flow rheology, reflects the magnitude of recent earthflow activity on the different hillslopes. The model accurately predicts the behavior of earthflow collection and transport zones observed in the field and estimates long‐term average sediment fluxes that are due to earthflows, in agreement with historical rates at our field sites. Finally, our model predicts that steady state hillslope relief in earthflow‐prone terrain increases nonlinearly with the tectonic uplift rate, suggesting that the mean hillslope angle may record uplift rate in earthflow‐prone landscapes even at high uplift rates, where threshold slope processes normally limit further topographic development.

A geophysical study was carried out in the vicinity of two collapsed and concealed septic tanks to delineate the structures responsible for their failure. Two-dimensional resistivity and seismic refraction tomography data were collected along a profile laid across the septic tanks. The data were collected using ABEM Terrameter SAS 4000, aided with LUND imaging equipment and seismograph, Terralloc MK6 respectively. The data were processed using REFLEX-W and RES2DINV software respectively. Pseudosections obtained show that the vicinity of the septic tanks is characterized by resistivity of 10–5200 Ωm and p-wave velocity of 320–2400 ms-1. Results show that these ranges encompass those of clay and sandy clay at shallow depths, and granite and gneiss in a shallow and undulating basement. The zones where the tanks were apparently sited show very low p-wave velocity of < 600 ms-1 and on the contrary, very high electrical resistivity of >5000 Ωm which suggest the presence of trapped air column. Based on the interpreted results, the tanks are estimated to be with lateral extent of about 6.5 m and depth of about 2.9 m. The delineated clayey soils at shallow depths suggest that there could be seasonal soil swelling and shrinkages due to seasonal variation in moisture content of the clay. These most likely led to annual ground movements, cumulative soil creep and the subsequent collapse of the septic tanks.

There are many civil engineering projects in Taiwan that utilize geosynthetic reinforced soil retaining walls (GRSRW). Usually, a reduction factor is used to avoid creep from the reinforcements over the duration of the structure's lifetime at the designing phase. However, GRSRW are composed of reinforcements and backfill soils, which are relatively complicated in considering the soil-structure interactive creep behavior. Questions are consequently rising: If there is creep deformation of a GRSRW, is it coming from soil creep? What would be the total amount of the deformation after years? Is the amount acceptable by civil engineers? Are the tensile forces in the reinforcements increased with time? The complex soil-reinforcement interactive creep behavior of GRSRW can be analyzed by using finite element method to get more know-how. With the aim of understanding the creep behavior of GRSRW, the PLAXIS finite element computer program, which contains suitable models for time-dependent behavior, is employed in this study to simulate the creep behavior of a 5 meter standard designed GRSRW. The predicted results obtained from the PLAXIS simulation can be used to evaluate and to handle the creep behavior of GRSRW.

1. The effect of three-dimensionality of the site on the distribution of stressesσy above the tunnels is considerable; the narrower the site, the greater this effect. 2. A deficit of the values ofσy relative toγsy is noted in all stages of constructing the dam. 3. The maximum stressesσy above the tunnels are reached in the middle sections of the tunnels and are slightly less thanγsy, which can be considered equal to the latter. 4. Near the tunnel walls are noted zones having a practically zero value, which is an important factor that must be taken into account when calculating the strength of the tunnels. 5. The levels of stressesσy near the canyon walls considerably lag behindγsy, which applies to all construction stages. On the basis of calculating the SSS of the dam in a three-dimensional rheological formulation, we can propose a stepped scheme of the acting vertical loads, which leads to a saving of tunnel concrete.

Slow, shallow ground movements in a slope near Yellowknife caused excessive tilting of timber piles that supported an engineering structure. To avoid damage to the structure, the pile foundations had to be replaced by rigid concrete piers that were designed to resist the forces of the moving soil mass. Downhill movements were rather slow and, during an initial inspection, were indicated only by soil that was pushed up against a series of piles on their uphill sides, while gaps had formed on their downhill sides. No open cracks or bulging was observed on the slope. A stability analysis indicated that the slope was not in a state of limit equilibrium. To obtain a better understanding of the creep movements in the slope and their effect on the rigid concrete piers, extensive instrumentation was carried out after the construction of the piers. This included slope indicators, piezometers, thermistors, and total-pressure cells against one of the concrete piers. In addition, a triaxial testing program was undertaken in which the effect of cyclic pore-water pressure changes on the long-term deformations of the shallow clay layer was investigated. From the data collected in the field and laboratory, it could be concluded that (i) tilting of the original timber piles was caused by downslope movements related to cyclic pore-water increases; (ii) the lateral soil movements increased almost linearly with depth from 2 m below the ground surface, with no indication of a slip surface; and (iii) the pressures exerted by the moving soil mass against the rigid concrete piers within the soil mass were equal to the passive resistance activated within the moving soil mass. Key words : soil creep, slope movements, soil pressures, pore-water pressures, freezing pressures, permafrost, cyclic loading.

Soil exhibit viscous creep behavior, and the creep strain rate is known to change greatly with time. Various possible reasons for the changing creep rate are considered. The writers propose a mechanism for interparticle sliding that is both viscous and frictional. The mechanism is based upon rate process theory and leads to an expression for the sliding velocity of two contacting particles in terms of the ratio between the tangential and normal contact force components. This interparticle sliding mechanism was incorporated into a numerical discrete element model of a large assembly of circular particles. Numerical simulations with the assembly displayed creep behavior that is very similar to soils. The creep rate increased with greater applied stress, decreased rapidly with time, and exhibited creep rupture at large stress levels. Changes in the creep rate are shown to result from the changes in contact forces that accompanied deformation of the entire assembly. Such deformation‐dependent changes are thou...

In 1877, G. K. Gilbert reasoned that bedrock erosion is maximized under an intermediate soil thickness and declines as soils become thinner or thicker. Subsequent analyses of this "humped" functional relationship proposed that thin soils are unstable and that perturbations in soil thickness would lead to runaway thinning or thickening of the soil. To explore this issue, we developed a numerical model that simulates the physical weathering of bedrock by root fracture and tree throw. The coupled biogeomorphic model combines data on conifer population dynamics, rootwad volumes, tree throw frequency, and soil creep from the Pacific Northwest (USA). Although not hardwired into the model, a humped relationship emerges between bedrock erosion and soil thickness. The magnitudes of the predicted bedrock erosion rates and their functional dependency on soil thickness are consistent with independent field measurements from a coniferous landscape in the region. Imposed perturbations of soil erosion during model runs demonstrate that where bedrock weathering is episodic and localized, hillslope soils do not exhibit runaway thinning or thickening. The pit-and-mound topography created by tree throw produces an uneven distribution of soil thicknesses across a hillslope; thus, although episodes of increased erosion can lead to temporary soil thinning and even the exposure of bedrock patches, local areas of thick soils remain. These soil patches provide habitat for trees and serve as nucleation points for renewed bedrock erosion and soil production. Model results also suggest that where tree throw is a dominant weathering process, the initial mantling of bedrock is not only a vertical process but also a lateral process: soil mounds created by tree throw flatten over time, spreading soil over bedrock surfaces.

In order to assess the net effect and relative importance of geomorphic processes at two natural woodland sites in southeast Australia, 100 small tiles were placed on the soil surface in 1979 and their movement was monitored over the course of nearly three decades. Rates of tile burial and other tile displacement were considerable but also markedly random, being largely inconsistent with expected patterns of displacement by orthodox creep and rainwash processes. This included substantial upslope displacement and burial depths that ranged from zero to 5 cm. We suggest that such turbulent transport in the topsoil has mostly been caused by the direct and indirect transfer of soil and clasts by animals and plants (i.e. bioturbation). In addition to direct evidence of biota interacting with tiles, the effectiveness of bioturbation at our sites has been well established and the overall tile burial rate of 0·25 to 0·4 mm yr−1 is comparable to rates of surface mounding. Patterns of tile movement are generally consistent with soils-geomorphic theory regarding the biomantle and bioturbation-driven stonelayer formation, and provide further evidence that soil transfer and slope movement, in many situations, are markedly random and complex processes. Copyright © 2010 John Wiley & Sons, Ltd.

Denudation rates of small tributary valleys in the upper Rhone valley of the Swiss Central Alps vary by more than an order of magnitude within a very small distance (tens of kilometers). Morphometric data indicate two distinct erosion processes operate in these steep mountain valleys. We determined the rates of these processes using cosmogenic beryllium-10 (10Be) in pooled soil and stream sediment samples. Denudation in deep, glacially scoured valleys is characterized by rapid, non-uniform processes, such as debris flows and rock falls. In these steep valleys denudation rates are 760–2100 mm kyr−1. In those basins which show minimal previous glacial modification denudation rates are low with 60–560 mm kyr−1. The denudation rate in each basin represents a binary mixture between the rapid, non-uniform processes, and soil creep. The soil production rate measured with cosmogenic 10Be in soil samples averages at 60 mm kyr−1. Mixing calculations suggest that the debris flows and rock falls are occurring at rates up to 3000–7000 mm kyr−1. These very high rates occur in the absence of baselevel lowering, since the tributaries drain into the Rhone trunk stream up-stream of a knickzone. The flux-weighted spatial average of denudation rates for the upper Rhone valley is 1400 mm kyr−1, which is similar to rock uplift rates determined in this area from leveling. The pace and location of erosion processes are determined by the oscillation between a glacial and a non-glacial state, preventing the landscape from reaching equilibrium. Copyright © 2010 John Wiley & Sons, Ltd.

The analysis of consolidation in organic soils. This paper is devoted to the specifi c diffi culties connected to construction on problematic soils. Different type of structures like: road embankments, fl ood control levees, dykes and dams are often located in soft subsoil areas, which consists mainly of peat, calcareous soil with a very high content of calcium carbonate and other high plasticity organic and no organic soils. These soils can be characterized as highly deformable with low initial shear strength and an insuffi cient bearing capacity. Soft soils show a large deformation, both vertically and horizontally, under load. The settlements often appear very quickly and can also continue for a long time. The consolidation process consists here of two main stages: primary settlement and secondary (and tertiary) settlement (creep). It is essential to have a good quality description of physical and mechanical properties of soil before the calculation and construction stage. For calculations of each stage of settlement the different physical and mechanical parameters of problematic soil are applied. In this paper the analysis of organic soils deformation process is presented. The deformation characteristics were defi ned on the basis of laboratory tests results. Soil investigations were performed on peat samples taken from test site located in Olsztyn region. Laboratory test of physical properties and consolidation tests in oedometer were carried out. Based on laboratory test results the empirical relationships between stress and deformation as well as stress and time were elaborated in order to describe the primary consolidation in organic soils.

A model has been developed for creep due to viscous flow in a material containing a non-Newtonian, amorphous grain boundary phase. The model describes the process whereby glass is squeezed out from between grain boundary layers in compression, and flows toward grain boundary layers under tension. A pseudo steady state, in which the creep rate is constant, is seen at small strains. However, beyond a critical strain, the strain rate starts to decrease rapidly, and no creep is possible once adjacent grains come into contact. The maximum possible strain is twice as large in tension as in compression. This leads to a form of anisotropy which may explain the shift in neutral axis which occurs during flexural creep.

We report concentrations of cosmogenic 10 Be ( t 1/2 = 1.5 × 10 6 yrs) in soil excavated from a soil-mantled hillslope in Black Diamond Mines Regional Park, Contra Costa County, California. The most striking features of the data are: (1) the similarity in the downward decreasing trends of 10 Be concentrations in two soil profiles collected 75 m apart, (2) the coincidence in each soil profile of the soil/bedrock interface (as defined by visual inspection of soil pits) and the level at which 10 Be concentrations attain very low values ( ∼4 × 10 6 atoms/g), and (3) the extremely low 10 Be concentrations in the underlying regolith (0.5 × 10 6 atoms/gram). The inventory of 10 Be in these soils is low, equivalent to about 6000 yrs of 10 Be accumulation in a soil initially containing no 10 Be. On the basis of these measurements, and with the aid of simple models of soil ( 10 Be) motions on the hillslope, we conclude that 10 Be loss from the surface is dominated by its removal in soil by creep. We calculate local rates of bedrock-to-soil conversion of between 0.15 and 0.27 km/10 6 yrs. Comparing these with uplift rates determined for coastal regions of California indicates that soil creep alone is capable of removing soil from the local geomorphic system at a rate equivalent to the rate of uplift of much of the coast.

Seasonal changes in groundwater levels affect the rate of downhill creep movements in slopes. This process has been studied in triaxial tests on undisturbed specimens of a natural clay from Bluefish Lake, 50 km north of Yellowknife, N.W.T. Specimens were first anisotropically consolidated to low stresses that correspond to conditions at shallow depths in creeping slopes. Pore-water pressures (back pressures) in the specimens were then cycled systematically (over periods lasting 4–48 h) with the drainage leads open. Resulting axial and volumetric strains were measured, and shear and lateral strains deduced from them. Strain rates decreased with increasing total times of testing. They increased with increasing values of the ratio Δu/Δuf, with increasing values of deviator stress q, and with decreasing values of [Formula: see text]. Systematically increasing the pore-water pressures in the specimens produced clear estimates of failure at low stresses. Key words : slope, clay, creep, cyclic loading, ground water, triaxial.

The discrete element method (DEM) was used to stimulate creep processes in granular materials. The authors present the main features of the numerical model, which include a new viscous mechanism for particle sliding, a new feedback technique for maintaining constant stress during creep, and a scaling technique that allowed monitoring the long‐term creep behaviour of a granular assembly. The creep behaviour of the numerical model exhibited the essential characteristics of soil creep—a creep rate that decreased rapidly with time, an increase in the creep rate with the applied deviator stress, and the beginning of creep rupture. The model's numerical performance is discussed, and representative results are presented.

[1] For hillslopes undergoing “diffusive” soil transport, it is often assumed that the soil flux is proportional to the local land-surface gradient, where the coefficient of proportionality is like a diffusion coefficient. Inasmuch as transport involves quasi-random soil particle motions related to biomechanical mixing and similar dilational processes, a slope-dependent relation arises from a balance between particle fluxes that tend to loft a soil and gravitational settling of particles into available pore space. A specialized form of the Fokker-Planck equation adapted to such particle motions clarifies how the particle flux involves advective and diffusive parts. This in turn contributes to a kinematic description of the diffusion-like coefficient. Ingredients of this coefficient include an active soil thickness, a characteristic particle size, the porosity in excess of a consolidated porosity, and the rate of particle activation as a function of depth. These last two ingredients, vertical porosity structure and activation rate, in effect characterize the magnitude and frequency of settling particle motions related to biological activity and thereby set the rate constant of the transport process. The significance of land-surface slope is that it is a measure of the downslope component of slope-normal lofting that is balanced by settling. Because the diffusion-like coefficient contains the soil thickness, the analysis suggests that the soil flux is proportional to the “depth-slope” product. The analysis is consistent with published profiles of soil creep displacement and with published estimates of soil flux obtained by downslope integration of soil production rates for hillslopes in California and Australia.

Due to the continual rainfall and creep deformation occurring to the slope on left bank of the new river in the flood control projects in Liye west of Hunan, and a serious landslide was likely to occur to the slope. Based on the analysis of the mechanism of landslide and slope stability, and the stratum layer parameter inversion carried by the Least Square method, the authors finally decided to use prestressed cable and anchor for the treatment to the slope. The monitoring result indicated that this treatment plan is reliable and safe.

The seepage situation of cutting slope groundwater is simulated and analyzed with the finite element software ANSYS. Comparing and analyzing the seepage field distribution of setup plan for hole diameter, hole long, hole distance to different drainage holes, it gets that the incidence and effect for changes of hole diameter, long hole, hole distance to drainage seepage field distribution. Combined with the real project, it discusses the distribution of slope seepage field under drainage holes laying double row along elevation, and draws that drainage holes laying multi-row along elevation can significantly improve drainage effect. So it determines the design project for drainage curtain of water-rich and high-steep cutting slope. Then, through the geological prospecting and the hydrological conditions survey in the real engineering, combined with the results of drainage pipes with finite element analysis, the specific buried project of deep drainage pipes is identified. Moreover, according characteristics of deep drainage, the technology and the control requirements of corresponding construction are established. Finally, slope surface deformation and internal displacement are monitored by using GPS and inclinometer. Monitoring results for many times in 18 months are analyzed. The largest surface deformation is 41.4 mm, and the largest internal deformation is only 10 mm, all are less than the first order of allowing deformation 123.75 mm of 0.0025h (h is the height of slope). Slope stability is got, and it is further validated the slope has a good stability after the deep drainage treating.

This article examines the landslide disasters of July 27, 2008. It was concluded that rock near the road was weakened by water causing creep deformation. Also, heavy long-term rains in the area contributed to conditions right for landslides. Each of the three areas affected along the roadside were approached with a different technique. The landslide on the left side of the road was managed by using bolt reinforcement. The area between roads was managed by changing the line. To the right of the road an anchor line and antiskid stick was used.

Effects of basin geometry Owing to the functional relations between boundary conditions and hydraulic head distribution in a flow domain (Eqs. 2.1 and 2.2, respectively), changes in the geometry of the unit basin modify the patterns of flow and fluid-dynamic parameters. Typically, the result is an increase in the complexity of the basic distributions. Regional flow patterns are sensitive to two principal aspects of a basin's geometry, namely, the configuration of the water table and the relative depth of the basin, i.e. its depth-to-width ratio (Toth, 1963). The analysis below follows Toth's (1963) original study. First, the linear upper boundary of the unit basin is replaced by an undulating sinusoidal surface superimposed on a linear regional slope. Next, the basin's depth is changed while keeping the width of the basin's flank constant. The effects of significant breaks in the regional slope are then illustrated by conceptual schemata of four major types of regional land forms: (a) V-notch canyons, (b) intracratonic broad upland basins, (c) intermontane broad valleys, (d) cordillera-cum-foreland basins. Finally, Zijl's (1999) analysis of the effect of scale of the water-table's relief on flow-system types and their depth of penetration, and of the relation between spatial and temporal scales is reviewed.

Since rock has the nature to creep, the high rock slope will continue creeping for a long time after excavation. If a building is constructed and completed during this period of time, a rigid structure will come into being to hold back the creep of high rock slope. Meanwhile, the high rock slope will exert on the building a strong force which will lead to deformation of the building. Therefore, regarding the high rock slope as a viscoelastic body, using the Kelvin-Volter model and adopting the full Newton-Raphson law, the adaptive decline iterative method and viscoelastic numerical calculation method, this paper makes a non-linear finite element analysis and calculation on the deformation of high rock slope after excavation, simulates the state of deformation throughout the whole proces and carries on a thorough study on the horizontal displacement and distribution over time. The result shows that, after excavation, the displacement over time can be divided into three phases: the 1st phase is the instant elastic deformation; the 2nd phase the developing period of creep deformation; the 3rd phase the stabilizing period of creep deformation. After a comprehensive analysis, the result provides an important reference to prevent the negative effects of creep deformation during the construction of entrance building.

Water is the most sensitive factor affecting the mechanical characteristics of rock and soil mass. The increase in the water ratio of unsaturated soil mass reduces both instantaneous strength and long-term strength of soils and changes the soil’s creep property. In view of the close correlation of rock and soil mass with water action and effects over time, this chapter presents the concept of “unsaturated soil creep” based on the theories of unsaturated soil mechanics and creep soil mechanics. An unsaturated soil creep triaxial apparatus has been researched and developed based on the basic principles used in the application of unsaturated soil triaxial apparatus and triaxial creep apparatus. The law of the impact of matrix suction on the creep characteristics of the soil mass in the Qianjiangping landslide in the Three Gorges area has been applied, and an unsaturated soil creep model that can reflect the impact of matrix suction has been established through tests using the apparatus. The research result has facilitated a new approach for analyzing the long-term strength and deformation of unsaturated soils and predicting the long-term stability of the landslide under the action of reservoir water fluctuation or rainfall.

An observed log-log linear relationship between channel slope and contributing area is explained by the erosional physics that lead to catchment form. It is postulated that tectonic uplift is in balance with the fluvial erosion down wasting that dominates catchment erosion, and it is shown that this relationship results in the observed log-log linear relationship at dynamic equilibrium. In addition, it has been observed that there are deviations from this log-log linear relationship near the catchment divide, with observed slopes being lower than those predicted from the relationship. This is explained by noting that for small areas, fluvial erosion effects are dominated by soil creep and rain splash, modeled by diffusive physics. The area at which this deviation from log-log linearity occurs is that point on the hillslope at which diffusive physics, like soil creep and rain splash, begin to dominate fluvial erosion. These predictions are confirmed by numerical simulations using a catchment evolution model.

This study was initiated to determine the basic characteristics and genesis of soils on gentle to very steep slopes on two contrasting slope aspects. Two transects, a southwest (SW) and a northwest (NW) transect, were laid out on a sandstone ridge across the summit and steepest convex shoulder positions. The thickness of the O, A and E horizons was not related to slope gradient across soils on all slope gradients and aspects. This indicates that the present rate of soil formation is greater than erosion, the influence of erosion on steep slopes could be off-set by lateral movement of through-flow water above the B horizon, or the process of tree throw masks slope gradient effects. Solum depth, B horizon thickness, clay, Fe, and Al indexes decreased with increasing slope for both the NW and SW aspects. Organic carbon index decreased with increasing slope for the SW aspect. Decreases in effective precipitation over relatively larger surface areas at steep versus lower slope gradients, a longer influence of periglacial erosion following the Wisconsinan glacial advance, and present slow but significant soil creep could cause these differences in soil development across the slope. Solum depth, B horizon thickness, clay, Fe, and Al indexes showed a smaller decrease across the NW compared to the SW slope. Organic carbon did not decrease across the NW slope. The E horizon was also slightly thicker on the NW compared to the SW slope. These aspect differences were probably caused by less evaporation on “shaded” NW compared to “sunny” SW slopes which produce generally higher moisture levels and more effective eluviation and illuviation on the NW slope.

[1] Many landscapes are composed of ridges and valleys that are uniformly spaced, even where valley locations are not controlled by bedrock structure. Models of long-term landscape evolution have reproduced this phenomenon, yet the process by which uniformly spaced valleys develop is not well understood, and there is no quantitative framework for predicting valley spacing. Here we use a numerical landscape evolution model to investigate the development of uniform valley spacing. We find that evenly spaced valleys arise from a competition between adjacent drainage basins for drainage area (a proxy for water flux) and that the spacing becomes more uniform as the landscape approaches a topographic equilibrium. Valley spacing is most sensitive to the relative rates of advective erosion processes (such as stream incision) and diffusion-like mass transport (such as soil creep) and less sensitive to the magnitude of a threshold that limits the spatial extent of stream incision. Analysis of a large number of numerical solutions reveals that valley spacing scales with a ratio of characteristic diffusion and advection timescales that is analogous to a Peclet number. We use this result to derive expressions for equilibrium valley spacing and drainage basin relief as a function of the rates of advective and diffusive processes and the spatial extent of the landscape. The observed scaling relationships also provide insight into the cause of transitions from rill-like drainage networks to branching networks, the spatial scale of first-order drainage basins, the contributing area at which hillslopes transition into valleys, and the narrow range of width-to-length ratios of first-order basins.

Beds of size-sorted stones forming stripes perpendicular to the contour are conspicuous on hillsides of the Columbia Plateau. Stripes occur on terrain ranging from 0° to about 30° in steepness, often beginning among Mima-type mounds on mesa tops and extending downward onto steep, unmounded slopes. Four mechanisms of their origin have been hypothesized: 1) water erosion, 2) solifluction and soil creep, 3) weathering of rock outcrops, and 4) tunneling by pocket gophers. We measured characteristics of five stripes on slopes of differing exposure and steepness. These stripes were 58–124 m long, and widths showed a maximum range of 0.55–3.70 m. Data on physical and biotic characteristics of the stripes suggest that pocket gopher tunneling is a basic mechanism of stripe formation on gentle slopes, and that this mechanism is augmented by outcrop weathering and colluvial dynamics on steeper slopes, with erosion playing a secondary role.

Translational failures, with associated downslope earthflow components and shallow slides, appear to be the primary mechanism of hillslope denudation in the humid tropical forests of the mountains of eastern Puerto Rico. In-situ weathering of quartz diorite and marine-deposited volcaniclastics produces residual soil (saprolite; up to 21 m deep) / weathered rock profiles. Discontinuous zones of contrasting density and permeability particularly in quartz-diorite slopes at 0.5 m, and between 3 and 7 m, create both pathways and impedances for water that can result in excess pore pressures and, ultimately, aid in determining the location of failure planes and magnitudes of slope failures. In combination with relict fractures which create planes of weakness within the saprolite, and the potential significance of tensile stresses in the upper zone of saprolite (hypothesized to be caused by subsurface soil creep), shear failure can then occur during or after periods of heavy rainfall. Results of in-situ shear-strength testing show negative y -intercepts on the derived Mohr-Coulomb failure envelopes (approximately 50% of all tests) that are interpreted as apparent tensile stresses. Observation of tension cracks 1–2 m deep support the test data. Subsurface soil creep can cause extension of the soil and the development of tensile stresses along upper-slope segments. Shear-strength data support this hypothesis for both geologic types. Apparent values of maximum and mean tensile stress are greatest along upper slopes (16.5 and 6.29 kPa). Previously documented maximum rates of downslope movement coincided with local minima of shear strength, and the shear-strength minimum for all tests was located near 0.5 m below land surface, the shallow zone of contrasting permeabilities. These results indicate that subsurface soil creep, a slow semi-continuous process, may exert a profound influence on rapid, shallow slope failures in saprolitic soils. Data indicate that cove slopes in quartz diorite tend to be the most unstable when saturation levels reach 75%. Deep failures (7 m deep) appear the most critical but not the most frequent because pore pressure build-up will occur more rapidly in the upper perched zone of translocated clays before reaching the lower zone between 3 and 7 m. Frequent shallow failures could reduce the probability of deeper failures by removing overburden and reducing shear stress at depth. Deep failures are more likely to result from storm events of great duration and intensity. Sixty-six ‘naturally occurring’ and more than 100 ‘road-related’ landslides were mapped. Forest elevations exceed 1000 m, but the majority of these failures were found between 600 and 800 m in elevation. This appears to be the area where there is sufficient concentration of subsurface water to result in excess pore pressures. The high percentage of slope failures in the 600–800-m range, relative to the percentage at higher elevations, suggests that differences in soil-water processes are responsible for the form of these mountain slopes. Steep linear segments are maintained at higher elevations. Slope angles are reduced in the 600–800-m range by frequent shallow slides, creating a largely concave surface. In combination, slope segments above 800 m, and those between 600 and 800 m, produce the characteristic form of the mountains of eastern Puerto Rico.

Measurements of above and below-ground portions of woody plants ≤ m in height were made along a transect on a 31 ´ slope in tropical montane rain forest near treeline in northern Peru. Almost all stems were basally curved, and most of the belowground axes were curved and situated upslope relative to the stem base. Microscopic examination demonstrated that underground curvature, and the resulting aboveground basal stem curvature, was due to stem burial, followed by adventitious rooting. We suggest that it was litter creep and branch movements along the slope that caused this burial. A threshold model would best explain how and when these curvatures occur: plant form and growth will only be affected by soil creep and other noncatastrophic downslope forces when the plant is within critical size classes of stem diameter and rooting depth. [Key words: geomorphic processes, Peru, soil creep, tropical montane forest.]

The article presents the results of analysis of rheology properties of sandy-clay tailings (wastes) of kimberlite ore dressing of the diamond deposit (Russia, Arkhangelsk region). The coefficient of secondary compression as main parameter of soil's creep is defined by implementing standard one-dimensional consolidation test. The linear correlation between initial void ratio and coefficient of secondary compression of sandy-clay tailings were obtained. For numerical simulation of tailing's behaviour subject to its rheology properties in Soft Soil Creep (SSC) model (time independent behaviour) of PLAXIS software was used. According to laboratory tests calibration of SSC model was implemented. It allows predicting dam's safety and reliability for long-term outlook.

Pipelines in operation often experience various loadings due to operational and environmental conditions. Large strain may be accumulated in the pipes under these loadings, and it may eventually induce local buckling or even fractures on the pipes. It is a common practice that a stress relief procedure is applied to a pipe by removing the soil around the pipe, allowing the pipe to spring back to a zero load state. The frequency of stress relief procedure is dependent on the severity of loading and soil conditions. This project is intended to study the behavior of buried pipes subjected to repeated stress relief procedures. The buried pipeline at Pembina River Crossing in Lodgepole, Alberta was simulated using the finite element method and the results were compared with field measured data. The pipeline at Pembina River Cross is situated at the active soil movement locations. A finite element model was developed to simulate the slope movement and the pipeline response. The correlation between soil movement and precipitation was investigated. With shell elements for pipe, 3D-solid elements for soil, this model captures the global and local behavior of pipeline. Soil-pipe interaction was simulated by setting a weak layer of soil surrounding the pipeline. The model incorporates nonlinear material, slope soil creep and water table change. Modified Drucker-Prager Cap Model was applied to soils based on direct shear test results. The finite element model was calibrated by slope indicator data and strain gauge data with satisfactory agreement. The model was used to simulate the strain accumulation and the stress relief in the pipeline, before and after the stress relief operation. Reasonable agreement was achieved when compared to the field data. The model can be used to further understand the behavior of pipe under repeated soil movement and stress relief procedure. It can also be used to develop the optimum stress relief procedure and operating schedule.Copyright © 2006 by ASME

A fine-grained slope that exhibits slow movement rates was investigated to understand how geohydrological processes contribute to a consecutive development of mass movements in the Vorarlberg Alps, Austria. For that purpose intensive hydrometeorological, hydrogeological and geotechnical observations as well as surveying of surface movement rates were conducted during 1998–2001. Subsurface water dynamics at the creeping slope turned out to be dominated by a three-dimensional pressure system. The pressure reaction is triggered by fast infiltration of surface water and subsequent lateral water flow in the south-western part of the hillslope. The related pressure signal was shown to propagate further downhill, causing fast reactions of the piezometric head at 5Ð5 m depth on a daily time scale. The observed pressure reactions might belong to a temporary hillslope water body that extends further downhill. The related buoyancy forces could be one of the driving forces for the mass movement. A physically based hydrological model was adopted to model simultaneously surface and subsurface water dynamics including evapotranspiration and runoff production. It was possible to reproduce surface runoff and observed pressure reactions in principle. However, as soil hydraulic functions were only estimated on pedotransfer functions, a quantitative comparison between observed and simulated subsurface dynamics is not feasible. Nevertheless, the results suggest that it is possible to reconstruct important spatial structures based on sparse observations in the field which allow reasonable simulations with a physically based hydrological model. Copyright  2005 John Wiley & Sons, Ltd. KEY WORDS rainfall-induced landslides; soil creep; hydrological modelling; Vorarlberg; Austria; pressure propagation

In structural geology, viscous creep is generally recognized as the major deformation mechanism in the folding of rock layers through geological time scales of hundreds of thousands of years. Moreover, since deformation of rock salt by creep takes already place on relatively small time scales - weeks to months, say - creep is a relevant phenomenon when studying salt mining, notably the convergence of mine cavities and the land subsidence caused by it. While creep is the dominant process on relatively long time scales, elasticity plays a dominant role in processes that take place on relatively short time scales. The elastic response to a stress is a displacement; the shape of the rock is deformed instantaneously with respect to its initial shape. However, the viscous response of a rock to a stress is a relatively low velocity in the order of millimeters per months or years, say. In this paper we consider the two deformation phenomena creep and elasticity. In general, elasticity is a compressible phenomenon, while creep is incompressible. Here we approximate creep by the introduction of a negligibly small amount of compressibility, which makes creep velocity calculations similar to conventional elastic displacement calculations. Using this procedure, a standard finite element package for elasticity can be applied to viscous problems, also in combination with elasticity. The method has been demonstrated to upscaling of creep viscosities. © International Association for Mathematical Geology 2005.

The aim of the research are to measure the type of mass movement and landslide hazard zoning for settlement ite evaluation. Terrain unit and their characteristics are the main inputs. Terrain classification based on genetic, morphology, and lithology are important aspects in the mapping of terrain through aerial photo interpretation at scale 1 : 50.000. Sampling method is stratified random sampling. Data considered in this research consist of slope, soils, lithology, dissetion, lineament, land use, vegetation, morphometry of landslide. Laboratory analysis is done for soil physics determination. Scoring and addition method are applied in the landslide hazard zoning through GIS programme. The result of this research are that structural – denudational mountain unit shows highly landslide hazard with sil/debris slide, planar block slide as dominant processes, while in the structural – denudational hills and colluvial valley bottom and river terraces show moderately landslide hazard with soil/debris slide and soil creep as main processes and then in the peneplain and colluvial slope show low landslide hazard. The highly landslide hazard zone cover settlement at the area Krempong, Sucen, Karangseneng, Kedawung, and Margalelo.

[1] The long-term temporal evolution of soil thickness in hollows depends on the processes controlling the rates of colluvium accumulation and erosion. Accumulation is due to soil creep and mass-wasting processes from the adjacent slopes, while erosion of colluvial deposits is mainly due to debris flow and landsliding. An analysis of the long-term evolution of colluvial deposits is developed through a stochastic model of soil mass balance at a point accounting for colluvium infilling, expressed as a deterministic function of the deposit thickness, and soil erosion by shallow landslides, modeled as a random (Poisson) process. Landsliding is related to the characteristics of the triggering precipitation through an infinite-slope stability analysis, a kinematic model of hollow response to rainfall, and the intensity-duration-frequency curves characterizing the regime of extreme precipitation. This analysis provides a probabilistic representation of the long-term dynamics at a point of colluvium thickness as a function of the timescale of hollow infilling and of the frequency of triggering rainfalls. The model is solved both numerically and (under simplified conditions) analytically, showing the existence of different regimes in the temporal evolution of soil thickness. In the case of steep slopes (i.e., with slope angles, β, greater than the soil repose angle, ϕ) the hollow can be either in a supply-limited state or in event-limited conditions, depending on whether the dynamics are limited by the supply of sediment from the adjacent slopes or by the occurrence of rainstorms able to trigger landslides. Nevertheless, since the likelihood of landslide occurrence increases with increasing values of deposit thickness, colluvium accretion always leads to conditions favorable to landsliding. Vice versa, in the case of gentle slopes (i.e., β < ϕ) the probability of landsliding decreases with increasing values of soil thickness, and event-limited conditions may evolve into unconditionally stable states.

In contrast to other types of anchors, prestressed ground anchors (or tie-backs) are routinely used in clayey or cohesive soils. One of the problems that needs to be considered concerns soil creep (i.e. rheological properties). The load-deformation behavior of ground anchors has received considerable attention in recent years, but relatively little attention has been paid to the time dependency of deformation and pull out force of ground anchors embedded in creep-sensitive soils. Using the results of experimental investigations for ground anchors in clayey soils, a method of analysis is proposed to account for creep of ground anchors in tied-back structures.

In soil dynamics, the most common parameter for measuring soil damping is the equivalent viscous damping ratio, which is derived from the theory of a single-degree-of-freedom system with viscous dashpot. The results of a comprehensive literature review on the equivalent viscous damping ratio at small cyclic shear strain amplitudes, yc, between 0.0001% and 0.01% are presented and discussed. On the basis of the published data from different types of laboratory tests two important trends are established. The first is a significant increase of the scatter of the data points as the plasticity index of the soil, PI, decreases. This indicates that damping in low-plasticity clays and sands is more sensitive to factors such as confining stress, overconsolidation ratio and cyclic loading waveform than the damping in high-plasticity clays. The second trend is an increase of the damping ratio with PI. This trend with PI is opposite from the trend at yc > 0.01% established earlier, where damping ratio generally decreases with PI. An explanation is provided that the phenomena responsible for the increase of the damping ratio with PI at small yc are viscous creep and relaxation of the soil.

Variation in the nature of soils with topography can readily be appreciated by comparing thin, rocky soils of mountain tops with thick, fertile soils of lowland plains. However, even in relatively featureless lowlands, the nature of soil varies profoundly, depending on whether it is well or poorly drained. This aspect of soil formation is not completely independent of the others discussed here because vegetation, microclimate, and age of land surfaces vary in different parts of the landscape. In small areas, however, other factors may be limited to such an extent that variation across the landscape constitutes a well constrained set of soils (toposequence) for obtaining mathematical expressions for variations in topographically related soil features (topofunctions). The undulating till ridges abandoned from the last glacial advance (Cary Till, ca. 14 000 years old) in north central Iowa provide examples of toposequences that are all the more striking because of the subtle topography involved, i.e., a relief of only 5 m from well drained summit to boggy bottoms. Soils from the top of the ridge to the bog show marked decreases in gravel and mean grain size and increases in profile thickness and amounts of clay, organic matter, and carbonate (Fig. 11.1). As an example of a topofunction, the increase in thickness (y) of the soil with distance from the summit down the slope (x) can be expressed by a polynomial equation: y = 1.41 − 0.91x + 0.49x2 − 0.034x3 (Ruhe 1969).

For brittle solids microhardness testing may be the only means of producing plastic flow over a wide temperature range. Indentation creep is a possible method for assessing the time-dependent deformation of brittle materials, but the controlling mechanisms at lower temperatures are not well understood. Single crystal germanium is a good model material for a study of such behaviour, and Knoop indentation was carried out on n-doped material in the 〈110〉 and 〈100〉 orientations at temperatures between 20°C and 700°C with load times of 20 to 600 seconds. The results can be qualitatively explained by the different amount of slip interaction occurring beneath indentations at the two orientations. In the 〈110〉 orientation dislocations can move out into new undeformed material as the size of the indentations increases. The creep process is therefore controlled by the ease with which diverging slip can take place, and the creep exponent increases throughout the temperature range studied. However beneath 〈100〉 indentations the slip systems activated are continually becoming locked as creep takes place. Thus whilst the creep exponent initially increases with temperature, it becomes dominated by the rate at which recovery can take place and levels off to an approximately constant value.