Water-saturated Soil Research Articles

Revisiting the concept of 'enzymic latch' on carbon in peatlands.

Peatlands are long-term sinks of atmospheric carbon (C) largely due to water-saturated soil conditions, decay-resistant plant litter, and the presence of biochemical compounds such as soluble phenolics. As phenolics are known inhibitors of microbial enzymes in soils, the concept of the 'enzymic latch' on peat C was introduced, assuming that phenolics accumulate in peat water due to protection from degradation by oxidative enzymes as a result of anoxia. However, their inhibitory role in peat has not been unambiguously confirmed. We aimed to verify whether peat phenolics inhibit microbial and enzyme activities in laboratory-incubated Sphagnum litter, and bog and fen peat. Soluble humic substances were extracted from bog water as a source of natural phenolics and separated into two molecular-weight fractions. We tested the effects of (1) phenolics concentration, (2) their molecular weight and (3) anoxia on the activity of hydrolytic and oxidative enzymes, and on microbial respiration rate. The added phenolics did not suppress hydrolytic enzyme activities nor microbial respiration. Quite the contrary, phenolics addition (up to 1000mgL-1) sometimes supported enzyme and microbial activities, indicating that phenolics (or another constituent of peat humic substances) served as a source of C. The activities of hydrolytic enzymes did not vary between oxic and anoxic peat but were double in oxic than anoxic conditions in Sphagnum litter. Differences in enzymatic and microbial activities were driven by peat type with about three times greater microbial respiration rates and enzyme activities in fen peats. Our results do not support the concept of the enzymic latch, particularly its key assumption that peat phenolics inhibit hydrolytic enzymes. While the concept was established on oceanic peatlands with low phenolic concentrations, the peat microbial community in our experiments seemed acclimated to the naturally high phenolic concentrations, characteristic for other, non-oceanic northern peatlands. Thus, the enzymic latch should not be considered as a determinative mechanism preserving the global C store in peatlands.

TO DETERMINE THE PHYSICAL AND MECHANICAL PROPERTIES OF THE SOIL OF LANDSLIDE SLOPES FROM THE DEGREE OF POROSITY AND HUMIDITY

The results of theoretical and experimental works devoted to the determination of the physical and mechanical properties of water–saturated soil are analyzed. On the basis of a comprehensive analysis, conclusions are formulated, and a method is proposed for determining the Young’s modulus and Poisson’s ratio for water-saturated soil, depending on humidity (degree of saturation) and porosity. Tables of data on the physical and mechanical properties of water–saturated soil are proposed. The study established the places of formation of local stress concentrations along the inclined layer. The values of dangerous stress concentrations found in various areas of the mountain slope that are vulnerable to collapse are shown in the tables.

Plants jamming on water-saturated soils during contact with the supporting elements (feet) of walking machines

Walking machines when working on waterlogged soils can be more efficient than wheeled machines. They provide increased ground passability and destroy the soil to a lesser extent. The paper discusses the results of studies of plant jamming by the feet of walking machines. Stamp tests of contact interaction of feet of various shapes with water-saturated soil were carried out. It was found that the greatest damage to the plant is obtained along the perimeter of the foot. This was the case at any depth of the footprint. Plants damaged by the foot, even in the case of small-sized feet, continued to grow after a period of depression. Wheeled and tracked movers, due to slipping and milling effect, are damaging plants to a higher extent. Mathematical modeling of the contact interaction of the foot with weak-bearing soil by the methods of finite element modeling has been carried out. Dimensional contact model for rigid feet of various shapes interacting with elastoplastic soil is formulated. The task was solved under conditions of large deformations of the supporting surface. The regularities of the stress-strain state of the soil in the zone of its contact with the foot under simple normal loading are obtained. Modeling shows that the greatest stresses occur along the perimeter of the foot, and the soil inside the perimeter is less loaded. This explains the nature of the plant jamming. Thus, the walking mode of movement in irrigated agriculture can provide lower plant jamming in comparison with traditional machines. Considering the smaller area of soil compaction and the absence of a continuous track, which is one of the causes of water erosion of the soil, it can be concluded that it is advisable to use small-sized feet.

Analysis of the Stress-Strain State of the Pipeline in the Areas of Frost Heaving of the Soil Using the SCAD Software Package

The article is devoted to the actual problem of construction and operation of pipelines in difficult geological conditions. The paper analyzes the interaction of permafrost soils with underground structures. One of the main problems is considered the soil heaving - the ability of water-saturated soils to increase its volume when frozen. The authors analyzed one of the existing calculation methods for determining the stress-strain state of a pipeline laid on heaving soils; the dependences of the determination of the normal forces of frost heaving have been investigated; calculated the values of stresses and displacements in the SCAD software package. It was revealed that the problems associated with the phenomenon of changes in the volume of soils with temperature drops depend both on the rate of soil freezing and on the length of the heaving section.

Calculation model of the “building-foundation” system on anisotropic base and deformation calculations

In the construction of new buildings and facilities although the requirements of construction laws, building codes are observed, the heeling process and the collapse of the urban high-rise buildings are continuing at different speeds. Unfortunately, the number of such collapses and destruction in the world continues to this day. The purpose of this article is to show the mechanisms of collapse and patterns of deformation of loose and water-saturated soils of the construction site, which often have anisotropic structures by creating a calculated mechanical and mathematical model. A brief overview shows the state of the issue on the scale of the consequences of the collapse of modern high-rise buildings in the world. Attention is drawn to the lack of knowledge of the soil bases of structures of anisotropic structure. A computational model of a soil ground of complex anisotropic structure and algorithms for its application in practical calculations are proposed. The results of studies and their analysis, the regularities of the deformation state of the system consisting of foundation and buildings base, depending on the angle of inclination of the inclined layered base are developed in the study as well. In the form of tables and a large number of drawings there are the elucidated basic laws of inclination of buildings and structures that took place in large cities of Kazakhstan.

Calculation model of the “building-foundation” system on anisotropic base and deformation calculations

In the construction of new buildings and facilities although the requirements of construction laws, building codes are observed, the heeling process and the collapse of the urban high-rise buildings are continuing at different speeds. Unfortunately, the number of such collapses and destruction in the world continues to this day. The purpose of this article is to show the mechanisms of collapse and patterns of deformation of loose and water-saturated soils of the construction site, which often have anisotropic structures by creating a calculated mechanical and mathematical model. A brief overview shows the state of the issue on the scale of the consequences of the collapse of modern high-rise buildings in the world. Attention is drawn to the lack of knowledge of the soil bases of structures of anisotropic structure. A computational model of a soil ground of complex anisotropic structure and algorithms for its application in practical calculations are proposed. The results of studies and their analysis, the regularities of the deformation state of the system consisting of foundation and buildings base, depending on the angle of inclination of the inclined layered base are developed in the study as well. In the form of tables and a large number of drawings there are the elucidated basic laws of inclination of buildings and structures that took place in large cities of Kazakhstan.

Natural attenuation of large anthropogenic nitrate loads in a subtropical stream revealed by δ15N and δ18O

Nitrogen pollution in subtropical waters is rapidly increasing due to land-use change, but specific sources, transformations, and attenuation rates remain understudied compared to cooler temperate catchments. Here, we quantify high-resolution nitrate (NO3−-N) loads, sources and natural attenuation in a subtropical creek in Australia over contrasting hydrological conditions. We observed large creek NO3−-N loads (ranging from 44 to 2938 μmol m−2 catchment d−1) exceeding the bottom-up estimates of nitrogen input to the catchment at the most upstream sites. Stable isotope natural abundances (δ15N and δ18O in NO3−-N) and Bayesian analysis revealed that greywater was the dominant source accounting for ~55% of NO3−-N in the upper creek, but fertilisers (~29%) and rainfall (~16%) were also relevant NO3−-N sources. NO3−-N loads at the most downstream site were only 0.2–9.7% of loads at the most upstream site. The resulting NO3−-N attenuation efficiency (mainly via denitrification) was 52–84% of original upstream load per km of creek, depending on hydrological conditions. This large capacity to attenuate NO3−-N during dry and first-flush events exceeds the attenuation found in temperate creeks subject to several decades of pollution in the northern hemisphere. During periods of high water flow and saturated soils, high NO3−-N loads were exported downstream, turning the creek from a natural bioreactor to a system resembling a flow-through pipe. In spite of effective natural nitrogen attenuation providing a valuable ecosystem service, concentrations and loads remained well above expected for natural systems and water quality guidelines. Overall, our results highlight the need for modifying fertiliser use, capturing nitrogen on farms and reducing greywater nitrogen to prevent significant losses to subtropical waterways.

Assessment of the size selectivity of eroded sediment in a partially saturated sandy loam soil using scouring experiments

Infiltrating water accumulates in the plough pan because of the low permeability of this layer, which results in saturation or partial saturation (soil water contents between the field water capacity and saturated water content) of the cultivated layer during continuous rainfall. Even in sloping farmlands, soil infiltration via large pores created by roots, wormholes and straw rot continuously increases, and the infiltrating water forms subsurface flow above the plough pan, causing the soil in the cultivated layer to become partially saturated. The processes and characteristics of soil particle sorting and transport in partially saturated soil were investigated in the laboratory using scouring experiments. The results showed that the stability of the aggregates was destroyed when the soil was in a soaking state and tended to be saturated, which produced a unimodal distribution of eroded sediment finer than 0.021 mm, and the main transport mechanism along the partially saturated soil was suspension/saltation. The eroded sediment in the erosion process was mainly composed of silt-sized particles, accounting for approximately 44–60% of the sediment load. Destruction of aggregates during erosion can easily enrich the soil in fine particles, especially clay-sized particles. Most fine and coarse sand-sized particles were predominantly aggregates of other finer particles; the aggregation of fine sand-sized particles was relatively poor, and a certain number of fine sand-sized particles were transported as single particles. The results reported in this study have important implications for an in-depth understanding of sediment transport in partially saturated soil.

Estimation of soil water retention curves from soil bulk electrical conductivity and water content measurements

Measurement of soil water retention curves (SWRCs) is time consuming, and there is no single laboratory device available to measure a SWRC over an entire range of relevant pressures. The van Genuchten (vG) model is commonly used to characterize the shape of the SWRC. Bulk soil electrical conductivity as a function of water content, σ(θ), has been used to estimate hydraulic properties of unsaturated soils, thus making it possible to relate σ(θ) and SWRC. The saturated and residual water content values, θs and θr, can be estimated from soil bulk density and particle size distribution. In this study, we present an approach to estimate vG parameters m and α from σ measured at saturated and residual soil water contents, as well as σ(θ) values measured at intermediate water contents. A thermo-time domain reflectometry (thermo-TDR) sensor is used to measure σ and θ of the same soil sample volume. SWRCs for three soils (Glassil 530 sand, Tennessee silt loam and Illinois clay loam with bulk densities ranging from 1.52 to 1.67 g cm−3, 1.05 to 1.25 g cm−3 and 1.05 to 1.2 g cm−3, respectively) are estimated from σ(θ) measurements and compared with direct SWRC measurements obtained with a tension table and pressure plate extractors. Additional comparisons are made using data obtained from the literature. The proposed method to estimate SWRCs performs well when compared to direct SWRC measurements (with an average RMSE and an average bias of 0.041 cm3 cm−3 and 0.008 cm3 cm−3, respectively). Results indicate that the new σ(θ) based method accurately estimates SWRCs.

Optimizing biochar application to improve soil physical and hydraulic properties in saline-alkali soils

Biochar application has been a promising approach to improve soil quality but their optimal amount in improving physical and hydraulic properties remains contradictory and inconclusive. The objective of this study was to examine and propose an optimal biochar application amount in saline alkali soil considering their impact on soil physical and hydraulic properties. A three-year field experiment was conducted in the saline-alkali soils under plastic film-mulched drip irrigation in Xinjiang, China. The studied physical and hydraulic properties included bulk density, soil porosity, saturated soil water content (θs), permanent wilting point (PWP), field capacity (FC), plant available water (PAW), spatial distribution of soil water content, planar soil water storage (PSWS), and soil evaporation. The treatments included biochar application amounts of 0 (CK), 10 (B10), 50 (B50), and 100 t ha−1 (B100) in 2018. Additional two treatments with 25 t ha−1 (B25) and 30 t ha−1 (B30) were added in 2019 and 2020, respectively. A four-parameter Gaussian function was fitted to the single-peak curves of the studied hydraulic properties vs. biochar application amounts to determine the most optimal biochar application amount. The results indicated that: (1) All of the biochar treatments significantly decreased bulk density and increased soil porosity over CK; (2) B10 and B25 treatments significantly increased θs, FC, PAW, PWP, and PSWS of root zones in the film-mulched zones over CK, but reverse results were observed in the B50 and B100 treatments; (3) Daily and cumulative soil evaporation were increased in no mulch zones of all biochar treatments over CK; (4) A dose of 21.9 t ha−1 was recommended as the most optimal biochar application amount for improving physical and hydraulic properties of saline-alkali soil. This research provided useful information on biochar application amounts for improving physical and hydraulic properties in saline-alkali soil.

Infiltration models and soil characterisation for hemispherical and disc sources based on Green-Ampt assumptions

In the present paper a set of physically based expressions for estimating the infiltrated volume and the flow rate from hemispherical and disc sources are presented. The proposed formula depends on four parameters: the initial and the saturated soil water contents, the saturated hydraulic conductivity and the wetting front suction head. The developed models allow the accurate estimation of the infiltrated flow when compared with the same phenomena simulated with Richardś equation. Dimensionless expressions were also deduced which help draw general conclusions on the infiltration processes. Taking advantage of the small number of parameters included in the developed expressions, it was proposed a simple procedure for soils characterization. The method requires measuring both the initial and saturated soil water content and the infiltrated volume over time from a disc source and, aided with the developed expressions, allows deducing both the saturated hydraulic conductivity and the wetting front suction head.

An experimental study of the relationship between the matric potential, unfrozen water, and segregated ice of saturated freezing soil

Frost heave damage is caused by the in situ freezing of pore water and segregated ice due to moisture migration. Previous studies have shown that in freezing soil, moisture migration is related to the pore water pressure gradient, and moisture migration is the dominant reason for the formation of an ice lens. However, the essential relationship between ice segregation and the matric potential is still controversial. Using a pF meter sensor, a 5TM volume water content sensor, and a digital image capture system, the relationship between the matric potential and the unfrozen water in saturated freezing soil was monitored in real time, and digital images of the formation of segregated ice were collected. Furthermore, the time space coupling relationships between the unfrozen water, the matric potential, the frost-heaving amount, the moisture migration, and the formation of an ice lens were systematically analyzed during soil freezing. The results demonstrate that there is an internal relationship between the moisture migration driven by the matric potential (from the micro-perspective) and the segregated ice layer effect (from the macroscopic perspective). In addition, the unfrozen water and the matric potential in the frozen area have a significant impact on the distribution of the segregated ice lenses.

Simulation Monitoring for Rainfall Infiltration in Soil Based on High Density Electrical Method

Rainfall infiltration is a porous medium flow problem with variable saturation. Based on the theoretical analysis of the flow field, electrical conductivity of rocks, the electrical field, the paper simulates the coupling relationship between the water saturation in soil and the apparent resistivity distribution. It combines the Richards equation, the Archie formula and the Laplace equation. The experiment simulates the potential field data by the Wenner setting in electrical exploration on a two-layer geologic model with continuous rainfall during 5 days, which shows that the effective saturation in soil is increasing with the rainfall time, while the apparent resistivity is decreasing. This can provide a theoretical basis for the analyzing the rainfall infiltration and porosity of the soil by using high-density electrical method in the future.

Validation of a thermo-hydro-mechanical model of freezing of water-saturated soil based on laboratory tests results

Frost heave of freezing water-saturated soils is an important worldwide problem from an engineering point of view. In cold regions, this phenomenon significantly affects foundations of buildings and road pavements. Application of artificial ground freezing to underground construction due to frost heave can cause an undesirable uplift of the ground surface and an increase in pressure acting on a lining and frozen wall. In the present paper, a mathematical model of soil freezing enabling one to predict soil deformation due to phase transformation of pore water into ice is proposed. The model is based on a set of nonlinear equations of water transfer, heat transfer, and equilibrium which are solved relative to porosity, temperature, and displacement variables. Constitutive relations of the poromechanics theory along with Bishop-type effective stress are used to simulate the mechanical behavior of soil during the process of pore water freezing and to evaluate pore pressure depending on a changein porosity and volumetric strain. Moreover, equations of the associated flow rule of plasticity are incorporated into the model to describe an inelastic volumetric expansion of the freezing soil induced by pore ice pressure. The ability of the model to capture essential features of the freezing process of water-saturated soils is demonstrated by numerical simulation of two laboratory tests. For the first test, a comparison between results of the numerical simulation and experimental measurements of variations of temperature and uplift of the top surface of silty clay specimens with time has been conducted. It has been shown that the numerical results are highly consistent with the measurements when the soil specimen is frozen with the growth of a massive cryogenic structure. In the numerical simulation of the second test, the calculated radial deformation of freezing soil is in good agreement with the experimental measurements, obtained by a fiber-optical sensor during the radial freezing of the quartz sand sample in a closed system.

Responses of phreatophyte transpiration to falling water table in hyper-arid and arid regions, Northwest China

Quantitative assessment of the impact of groundwater depletion on phreatophytes in (hyper-) arid regions is key to sustainable groundwater management. However, a parsimonious model for predicting the response of phreatophytes to a decrease of the water table is lacking. A variable saturated flow model, HYDRUS-1D, was used to numerically assess the influences of depth to the water table (DWT) and mean annual precipitation (MAP) on transpiration of groundwater-dependent vegetation in (hyper-) arid regions of northwest China. An exponential relationship is found for the normalized transpiration (a ratio of transpiration at a certain DWT to transpiration at 1 m depth, Ta*) with increasing DWT, while a positive linear relationship is identified between Ta* and annual precipitation. Sensitivity analysis shows that the model is insensitive to parameters, such as saturated soil hydraulic conductivity and water stress parameters, indicated by an insignificant variation (less than 20% in most cases) under ± 50% changes of these parameters. Based on these two relationships, a universal model has been developed to predict the response of phreatophyte transpiration to groundwater drawdown for (hyper-) arid regions using MAP only. The estimated Ta* from the model is reasonable by comparing with published measured values.© 2021 China Geology Editorial Office.

Conditions of soils dilution of dams under seismic impacts

This report presents the results of the author's research on the dilution of water-saturated cohesive soils in the conditions of concussions. The nature of the weakening of the soil connectivity during vibration and the dynamic pressure that occurs in the thickness during the compaction of the disturbed soil structures, which contribute to the liquefaction and spreading of the soil from the body of the structure, is described. The criterion of the possibility of violation of the soil structure in the conditions of concussions is given. A theoretical method for determining this important indicator of the seismic strength of the soil is given.

华北山区典型人工林土壤水势动态和水分运移规律

大规模植树造林工程有效缓解了我国北方水土流失等问题，但伴随植被生长和降水格局变化，水循环过程发生明显改变。土壤水分运动是水循环的关键过程，研究变化环境下人工林植被土壤水分运移规律，对植被生态恢复具有重要意义。基于2014-2018年多时间尺度（半小时、天、月和年）华北山区崇陵流域典型人工侧柏林和荒草土壤剖面水势监测数据，阐明不同植被覆盖下土水势动态变化规律，提出土壤水分运移和植被水分利用模式。研究结果表明：侧柏林土壤水势日变幅显著低于荒草植被，但土水势日变幅随土壤深度增加而减小的速率90 a侧柏依次大于60 a侧柏和荒草；月、年尺度侧柏林不同深度土水势变化对降水的响应大于荒草地，其中60 a侧柏林年均土水势与年降雨量显著线性相关（P<0.05）。由水势梯度和零通量面多年平均变化可知，90 a侧柏林0-50 cm土壤水呈下渗趋势，根系水力提升促使50-100 cm土壤水向上蒸散；60 a侧柏林0-20 cm、70-100 cm以及枯水年30-70 cm土壤水均以蒸散为主，根系可同时吸收利用表层和深层土壤水分；荒草地0-20 cm土壤水分蒸发强烈，且为根系主要吸水深度，20-100 cm土壤水稳定下渗。相比60 a侧柏林和荒草，90 a侧柏林的土壤调蓄能力增强，与荒草互被可减少植被间水分竞争，充分利用土壤水，从而减少流域内地表径流和土壤侵蚀量。;Large scale afforestation alleviates soil erosion effectively in North China. The water cycle has been consequently modified under plant growth and changing precipitation regimes. Soil water dynamics is critical to investigate the water cycle of planted forests under changing environment for plant restoration. In this study, multi-time scale (i.e. half-hourly, daily, monthly, and annual scales) analysis of soil water potential (SWP) was conducted based on long-term measurement of the SWP between 2014 and 2018 under 60 a and 90 a arborvitae (Platycladus orientalis) planted forests as well as weeds as a reference in Chongling catchment in the mountain area of North China. The temporal variations in vertical gradients of SWP and zero flux planes (ZFPs) were analyzed to propose the patterns of soil water movement and plant water utilization for three representative vegetation types. Results showed that the diurnal variation of the SWP appeared as a unimodal curve with a peak occurring between 13:00 and 14:00. Daily variation in the SWP of arborvitae was significantly small compared to that of weeds. Daily changes of SWP decreased with the increase of soil depth, while the declining rate was larger under 90 a arborvitae than that under 60 a arborvitae and weeds. It was evident that the SWP decreased gradually from April to June, reaching a minimum value of -305.3 cm with the standard deviation (SD) of 58.3 cm. Nevertheless, the SWP increased rapidly from July to August ((-215.7±105.9) cm) and then remained high during September to October ((-210.6±51.9) cm). The responses of SWP at different soil depths to precipitation under arborvitae at monthly and annual scale were greater than those under weeds. There was a significant linear relationship between the annual mean SWP and annual precipitation under 60 a arborvitae (P<0.05). Based on the depth distributions of SWP gradients and ZFPs in the experimental years, soil water infiltration was estimated to mainly appear at upper 50 cm depth but root hydraulic lift facilitated soil moisture moving upwards in the 50-100 cm layer under 90 a arborvitae. The soil moisture in the 0-20 cm and 70-100 cm layers as well as that in the 30-70 cm layer in dry year mainly moved upwards and were taken up by plant roots under 60 a arborvitae. Strong evaporation and root water uptake primarily occurred at the top of 20 cm for weeds, while soil water infiltrated steadily in the 20-100 cm layer. It was found that soil water storage capacity under 90 a arborvitae was stronger than that under 60 a arborvitae and weeds, as it had smaller soil bulk density and increased the saturated soil water content. The planted forest of 90 a arborvitae coexisting with weeds could reduce water competition among different species and improve the water use efficiency. Surface runoff as well as soil erosion would be further reduced in the catchment. This study demonstrated the modifications of soil water dynamics and water utilization of the representative planted forests on the basis of long-term observations and multi-time scale analysis of SWP in Chongling catchment. It provided new insights into ecological restoration and water management in North China under changing environment.

Dynamic Characteristics of Transport Structures

There exists a great need to increase the bearing capacity of soils when building high embankments on a weak foundation in seismically hazardous areas. The article considers two methods for testing soils under dynamic conditions: 1) cyclic triaxial compression, which is used to determine the dynamic strength of water-saturated soils by cyclic triaxial tests with controlled load, as well as shear modulus and damping coefficient; 2) low-amplitude dynamic vibrations (resonance column) to determine the shear wave velocity, shear modulus and soil damping coefficient in a small range of shear deformations, which can be widely used in engineering seismology. In laboratory tests using the cyclic triaxial compression method, data are obtained with a high degree of accuracy for high strain levels, the results of which can be used in the integral Fourier transform. Spetras are used in engineering seismology and as a basic tool for assessing the spectral composition of recorded ground motion or structure response, as well as for assessing ground motion from fundamental seismological parameters in regions where ground motion records are not available. After carrying out these tests and analyzing the amplitude Fourier spectra of accelerations, velocities and displacements, the calculation results will be obtained.

Расчет консолидации грунтов с учетом всех основных параметров, влияющих на данный процесс

The search for ways of accelerating the preparation of bases on water-saturated boggy areas is an up-to-date problem and requires further scientific study. The conducted researches made it possible to establish that vibration can be an effective means of accelerating the consolidation of water-saturated soils of the bases. Using theoretical and experimental research, a method for numerical solution of the problem was developed.

Justification of dump parameters in conditions of high water saturation of soils

The object of research is the stability parameters of the massif of a single-tier dump of soft overburden rocks with a flooded slope when it is formed by a dragline excavator. One of the most problematic areas is determining the safe distance of the dragline excavator from the upper edge of the slope in the conditions of the formation of a single-tier dump of soft overburden rocks, flooded with water.The calculation of the width of the prism of possible shift was carried out using the Rocscience Slide software, which, taking into account the parameters of the slope and the physical and mechanical properties of the rock mass, automatically restores a number of curved sliding surfaces for individual safety factors. The obtained data were processed using the Microsoft Excel software, thanks to which, by the least squares method, graphs of the functions of the possible shift prism width from the height of the tier of a dump of soft overburden rocks and the level of its flooding were constructed.For the conditions of the formation of a single-tier dump of soft rocks of overburden with a height of 40–100 m and a flooding level of 0–30 m, the width of the prism of a possible shift was calculated for sliding surfaces with a safety factor of 1 and 1.2. These values are, respectively, 0–85.9 m and 0–122.6 m within the established calculation limits and depending on the method of constructing curved surfaces. The distance between the points of intersection of the horizontal surface of the tier with curved sliding surfaces with a safety factor of 1 and 1.2 is 16–52.5 m. The dependences of the width of the prism of possible shift (a) on the height of the tier of a dump of soft overburden rocks (Ho) and its level flooding (Hw), taking into account the physical and mechanical properties of the dumped mountain range, including saturated with water. The minimum deviation from the initial value of the coordinates of the points is achieved when setting the second-degree polynomial as the trend line for the function a=f(Hw), and for a=f (Hо) – a straight line.The obtained data for calculating the parameters of the possible shift prism suggest the possibility of forming a single-tier dump of soft overburden rocks with a height of 40–60 m with unloading of rock mass into the worked-out space and 70–100 m with loading the unstable part of the slope with an EK-11/70 excavator-dragline (Novokramatorsk Machine-Building plant, Ukraine).