Soil Heave Research Articles

Study on use of chemically stabilized native expansive soil as cohesive non-swelling material

The growing infrastructural need requires extensive construction activities in various parts of the world. The problems posed by the expansive soils have caught the attention of the academia and industry at several work sites. Several remedies were suggested by various researchers like replacement of soils, physical, hydraulic & chemical modification of the local problematic soils, inclusion of cushion materials and other reinforcing materials etc. Among the various methods, inclusion of cushion materials under the foundations seemed to be economical and simple. Availability of cohesive non-swelling (CNS) materials to be used as a cushion at some work sites could not be very easy. This study utilizes the local expansive material stabilized with chemical and industrial wastes to prepare a suitable CNS material. Model tank studies with varied thickness of the CNS cushion prepared from this study was placed on the expansive soil were performed to find the efficacy of the CNS material in arresting the heave of the expansive soil. Four cycles of wetting and drying was carried out to check the stability of CNS materials under continuous swelling and shrinking. Results obtained from the model test results indicate that the CNS material prepared from the native expansive soil seem to be an effective CNS material that arrests considerable amount of heave when the thickness of the native CNS material was half of the soil thickness.

Design and Testing of Reverse-Rotating Soil-Taking-Type Hole-Forming Device of Pot Seedling Transplanting Machine for Rapeseed

To address the problem whereby the size of the hole formed by the existing hole-forming device of hole-punching transplanters is significantly inconsistent with the theoretical size as it is impacted by the inserting and lifting methods, a scheme for eliminating the forward speed of the whole machine by the horizontal linear velocity of reverse rotation of the hole-forming mechanism is proposed to vertically insert and lift the hole-forming device in accordance with the working characteristics of hole-punching transplanting and the agronomic requirements of rapeseed transplanting. In addition, a novel type of reverse-rotating soil-taking-type hole-forming device for the pot seedling transplanting machine for rapeseed was developed. A test bench for the hole-forming device was set and its effectiveness was verified in the soil bin. It was found, from the test results, that, when the forward speed of the hole-forming device was between 0.25 m/s and 0.45 m/s, the average qualified rates of hole forming of the device were 95.2%, 94.0% and 93.3%, respectively; the average change rates of the hole size were 2.3%, 2.9% and 5.5%, respectively; and the average error between the theoretical value of effective depth and the experimental value was between 2.0% and 5.6%. The average angle between the hole-forming stage trajectory of the hole opener and the horizontal direction at different forward speeds was higher than 88.0°; the coefficient of variation was between 0.16% and 0.64%; the perpendicularity of the hole-forming operation was high; the change rates of soil porosity of the hole wall were between 8.2% and 9.3%; and the average soil heave degrees at the hole mouth after the completion of the hole-forming operation were 3.9%, 4.1% and 4.2%, respectively. The average soil stability rates of the hole wall were 91.9%, 91.2% and 91.0%, respectively. The different performances of the hole-forming device were confirmed to meet the requirements of rapeseed pot seedling transplanting. This study can provide a reference for the structural improvement and optimization of the hole-punching transplanter for rapeseed pot seedlings.

Frost heave and frost susceptibility of soils on the projected railway Moscow–Kazan

Frost heave and factors which affect it are considered on the projected railway Moscow– Kazan. That region is intensively developed; however, frost heave hasn’t been well studied in there, especially at the present climatic conditions. Results of field studies of frost heave properties of grounds on monitoring sites along the railway Moscow–Kazan are presented; they include physical properties of grounds, depth of seasonal freezing, grounds thermal mode, groundwater dynamics, snow cover thickness and basic characteristics of frost heave.

Injection Compositions for Creating Impervious Screen for Roadbed Foundation

In order to limit the access of ground waters into the freezing zone and to reduce the value of frost heaving of the road bed soils to the maximum permissible values, the creation of impervious screens by injection method is proposed. Impervious screens are proposed to be made both by "horizontally-inclined" injectors from the slopes and by "vertically-inclined" injectors from the slopes and roadsides, depending on particular soil and hydrological conditions and using different types of injectors. Versatility of the proposed designs of impervious screens and injectors enables the use of various injection solutions and technologies of soil injection (pressure injection, injection in impregnation mode, jet injection, etc.). According to the laboratory research results, exponential dependences of the relative deformation of frost heaving have been established εfr (%) from the relative stabilization height hs/h of the freezing zones. It was established that the average relative strain of frost heave of specimens without stabilization was εfr = 6.2%. Stabilization of this soil with an aqueous solution of sodium silicate (Na2SiO3) enables to reduce the determined index to εfr = 0.7%, with Portland cement (M400) up to εfr = 0.5%, cationic-type surfactants on average up to εfr = 3.6%. The presence in the laboratory sample of an impervious screen in the lower frost zone made of silicified soil or soil stabilized with Portland cement, with a relative thickness of 1/3, reduces the frost heave of the samples to the values εfr = 1.9-3.5%, which is almost half as much as (Na2SiO3) and Portland cement (M400) for the control samples without stabilization. Such additives as an aqueous solution of sodium silicate have shown the greatest effectiveness within the framework of the problem to be solved. The decision to use a stabilizer depends on the specific soil conditions and the injection method and equipment to be used.

Unified Elastic Modulus Characteristic Curve Equation for Variably Saturated Soils

A soil’s elastic modulus is a fundamental property defining the soil’s reversible stress-strain relation under mechanical and environmental loadings. It has been observed that a soil’s elastic modulus can increase up to several orders of magnitude from fully saturated to dry conditions due to two distinct soil water retention mechanisms: adsorption and capillarity. Adsorption affects interparticle stress through van der Waals and electrostatic attraction and interparticle friction coefficient through water film retained by soil sorptive potential. Capillarity governs interparticle stress through capillary pressure and surface tension. The onset and scaling laws of the two mechanisms depend on the soil properties of specific surface area, pore-size distribution, cation exchange capacity, and soil mineralogy. These mechanisms are unified by a proposed elastic modulus characteristic curve (EMCC) equation. It is demonstrated that the proposed EMCC equation can well describe the moisture-dependent elastic modulus of a wide array of soils. Further, an interrelation among the EMCC equation, suction stress and soil shrinkage curves is established, which can greatly facilitate predicting suction stress from soil shrinkage curves and vice versa, further validating the EMCC equation in capturing soil’s hydromechanical behavior. The practical importance of the EMCC equation is demonstrated through prediction of ground heave of various soils due to a hypothetical flooding event.

Cryogenic Heaving of Peat and Peaty Soils

Cryogenic Heaving of Peat and Peaty Soils

Опытное определение скорости морозного пучения для различных типов грунтов по степени пучинистости

The present study was aimed at assessing in an experimental way the values of heaving rate for the Russian system of soil heaving classification. Based on the laboratory study of the frost heaving process of 25 different soil samples, there were obtained the values of heaving degree and frost heaving rate for each of them. Based on the analysis of the obtained data, the authors proposed values of frost heaving rates at the boundaries between different soil classes to be included in the Russian system of soil classification by heaving degree. In addition, there is proposed an approximation function that makes it possible to transfer from the value of the relative deformation of frost heaving to the frost heaving rate, which helps harmonizing the experience of Russian and foreign scientists and engineers.

Testing Deformation and Compressive Strength of the Frozen Fine-Grained Soils with Changed Porosity and Density

Abstract Current paper focuses on the laboratory experiments performed wit aim to test the deformation in the frozen loam soil specimens. Loam frozen soils are subject to the external effects, such as climate and environmental impacts including temperature changes. Soil heave is one of the key features restraining possible area development: construction of buildings, roads and railways. Necessarily, this requires the improvements of methods of the assessment of heave. This research evaluated the compressive strength and deformation in several specimens of the frozen soil. The approach included varying load and physical properties of soil specimens: porosity, pore filling, moisture, density of soil particles and dry soil density. Besides during the experiment, the external conditions were changed: decreased temperature and increased load pressure. The experiment is based on the UPG-MG4-01. The paper presented the laboratory tests of heave and compressive strength of the frozen soils using applied geotechnical methods.

Anti-frost heave design method for a parabolic canal based on the hydraulic optimal solution set in seasonally frozen regions

Parabolic canals are commonly used in seasonally frozen regions because of their excellent hydraulic characteristics and frost heave resistance. However, severe frost damage can still occur, mainly because the design of canals is based on experience, and the analytical mechnical models and design methods are limited. First, the frost heave characteristics of parabolic canals were analysed, and the canal lining was simplified as an arched thin shell structure under the normal frost heave force, tangential freezing force, and gravity. Second, an analytical mechanical model of frost damage to the lining was established, and the equations for the axial force, bending moment, tensile stress were derived; the accuracy of the model was verified by field measurements and numerical simulations of a canal case. Third, the effects of groundwater depth and canal size were analysed, and the frost damage mechanism was investigated. Fourth, the anti-frost heave design method of a canal based on the hydraulic optimal solution set was proposed, and the method was encapsulated into digital design software with Python language. This mechanical model can explain the frost damage of the canal, and the nonuniform frost heave of foundation soil caused by different groundwater depths in different parts of the canal is the cause of lining damage. The bi-objective optimization design method can consider the hydraulic performance and anti-frost heave performance of the canal, and the digital design software can assist engineers with developing a quick and accurate design approach. The research results can provide a theoretical basis and technical means for cold-region canal design.

Experimental investigation on frost heave characteristics of saturated clay soil under different stress levels and temperature gradients

The frost heave of soil has a significant influence on the stability and durability of various infrastructures. It is necessary to investigate the occurrence mechanism and development law of soil frost heaving. In this research, a triaxial frost heave experimental setup was developed, and a series of frost heave experiments were carried out by considering different confining pressures, deviator stresses, temperature gradients, and water supply conditions. The research found that the temperature gradient was the core driving force of soil frost heave. The increase of deviator stress and confining pressure would limit the development of frost heave by inhibiting water absorption. The growth of warm end temperature would increase the temperature of both water supply and soil near the warm end, which restrained the development of soil frost heaving. Finally, an improved prediction model for saturated clay soil's frost heave ratio was developed based on Takashi's one-dimensional frost heave ratio model, considering the effects of stress level and temperature gradient.

Inner soil heave of stiffened caisson during installation in soft-over-stiff clay

The identification of soil heaves inside a caisson during installation is important for the caisson’s design length, since the inner soil heave during the caisson installation affects the final effective caisson penetration depth, hence caisson capacity. This paper reports an extensive parametric study of stiffened caissons penetrating in double-layer of soft-over-stiff clay using large deformation finite element (LDFE) analyses. The LDFE analysis was first validated against the existing results from centrifuge tests and numerical analyses. Then the parametric study was carried out to explore the inner soil movements during stiffened caisson installations with various influencing factors, such as caisson diameter, caisson stiffener width, top-layer soil strength, double-layer soil strength ratio, and roughness of soil-caisson interface. It is found that the caisson diameter, stiffener width, and top-layer soil strength have significant influences on the inner soil behaviors. Besides, the movements of both soil surface and soil layer interface were also investigated. Based on the LDFE results, design formulas are proposed to estimate the inner soil heaves for soft-over-stiff clay. A design formula to estimate the movement of the soil layer interface for soft-over-stiff clays is also reported.

The cryogenic structure and texture of seasonally freezing soil in the steppe zone of the Trans-Volga-Urals region

The formation of ice lenses and associated frost heave were found in soils the steppe environment with positive mean annual air temperature. The ice lenses due to soil freezing occur in soils with expressed microrelief when they have additional ground moistening. In soils formed on quaternary loam with shallow groundwater the formation of ice was not differentiated across the microrelief; the morphology of the microrelief is similar to thufur. Soils formed on fine-dispersed limestone (chalky polygons) and on the material of ancient weathering crust (frost mounds) do not have clear evidence of subsoil extramoisterning exhibit the differentiated formation of cryotexture according to microrelief. The ice lenses were found in soils of microhights. The formation of cryogenic lenticular and platy structures occur after to the melting of ice lenses in soils. Local frost heave in steppe soils determines the small-scale differentiation of soil processes and the formation of the complex soil cover.

Ground deformation mechanism due to deep excavation in sand: 3D numerical modelling

In densely built areas, development of underground transportation system often involves excavations for basement construction and cut-and-cover tunnels which are sometimes inevitable to be constructed adjacent to existing structure. Inadequate support systems have always been major concern as excessive ground movement induced during excavation could damage to neighbouring structure. A detailed parametric analysis of the ground deformation mechanism due to excavation with different depths in sand with different densities (Dr=30%, 50%, 70% and 90%) is presented. 3D finite element analyses were carried out using a hypoplastic model, which considers strain-dependent and path-dependent soil stiffness. The computed results have revealed that the maximum settlement decreased substantially when the excavation is carried out in the sand with higher relative density. This is because of reason that sand with higher relative density possesses higher stiffness. Moreover, the depth of the maximum settlement of the wall decreases as the sandbecome denser.The ground movement flow is towards excavation in retained side of the excavation. On the other hand the soil heave was induced below the formation level at excavation side. The maximum strain level of 2.4% was induced around the diaphragm wall.

Monitoring of changes in the thermal regime in the road structure

Freezing of wet dispersed soils is accompanied by a number of physical, physicochemical and physicomechanical phenomena and processes. In soils, when water freezes, the properties of the soils themselves change abruptly and abruptly, and the volume of frozen soil increases significantly, and not evenly. It was revealed that during freezing conditions can arise under which an increase in soil volume due to moisture migration to the freezing front and its freezing can reach tens of percent. This process is usually called frost heaving of soils. This phenomenon refers to physical and mechanical processes, as a result of which, under the influence of thermodynamic changes, the freezing soil acquires a stress-strain state. To combat frost heaving, it is necessary to study the patterns of changes in the water-thermal regime of road structures. The article presents various methods for assessing the water-thermal regime of road structures. The developed system of temperature monitoring of the road structure to a depth of up to 3 m and some measurement results are described, which make it possible to assess the temperature change at different depths from the road surface.

Effect of freezing and thawing on soil permeability: newly equipment and experimental results

In a cold climate design of dams, clay barrier liners on landfills, and structures on frost-susceptible soils is a challenge for geotechnical engineers. During service life of the structures a frost heave may reach 15-20% of the depth of a frost penetration and an uplift movement are accompanied by the formation of layered or lattice cryogenic texture. When thawing, macro- and micropores are formed instead of ice lenses. Basically pores are oriented predominantly along frost front. They are a reason of horizontal water permeability increase, consequently, reduce of stability of the slopes and decrease of the effectiveness of the landfill clay barrier liners. The paper presents a new apparatus for studying water permeability and frost heave of soils which allows to carry out horizontal or/and vertical permeability tests (along and across layered cryogenic texture) after assigned number of freeze-thaw cycles without withdrawal of a soil sample from apparatus. The results for clay and fine sand samples are obtained. Clay and fine sand samples showed an increase of horizontal hydraulic conductivity after 2 - 4 freeze-thaw cycles. Relationship between water flow velocity and hydraulic gradient for non-Darcian and Darcian flow is obtained as a result of vertical permeability tests of clay samples in unfrozen state.

A study on frost heave and thaw settlement of soil subjected to cyclic freeze-thaw conditions based on hydro-thermal-mechanical coupling analysis

Frost heave and thaw settlement are the main cause for damaging the engineering structures in the region of seasonally frozen soil. The soil freeze-thaw (FT) deformation is a typical complex result of multiple physical fields and involves the process of water transfer, heat transfer, ice-water phase transition and stress redistribution. While the theory and model of frost heave have been studied for decades, less attention has been paid to the simulation for soil deformation under FT cycles. In this study, coupled equations for water, heat and the deformation of frozen soil are derived based on previous theories and are realized in numerical software. The volumetric water content of the frozen soil in the experiment was tested by nuclear magnetic resonance (NMR) technology, and the obtained data were imported into the model. Experimental soil samples were arranged in improved model equipment, and the temperature and frost heave at different heights of the soil column varied with time. The model validity and applicability based on the hydro-thermal-mechanical coupled equations is verified by comparing the results of both the experiment and numerical simulation. In this research, from the curves of the soil temperature change, water content distribution, water flux occurred at the soil bottom surface, as well as the displacement of frost heave and thaw settlement, and the pore size distribution, the characteristics of the soil subjected to cyclic FT conditions was analyzed. The existed theoretical model cannot well model the soil FT deformation. Therefore, this study may provide references for developing more accurate theoretical models on the soil subjected to FT cycles.

The Frost Heaving and Heave Properties of Soils on the Projected Moscow–Kazan Railway

The Frost Heaving and Heave Properties of Soils on the Projected Moscow–Kazan Railway

The Strength Assessment for T-bar Penetrometer Tests at Shallow Embedment in Clay considering Strain Softening

The undrained shear strength of clay is important for deep-sea foundation design. T-bar penetrometer as a key tool has been widely used in laboratory and offshore site investigation. To obtain a continuous soil strength profile, it is necessary to apply shallow corrections before the penetrometer reaching the full-flow state. Meanwhile, the actual soil strength may be underestimated if the strain softening behavior is not considered. In this study, the process of T-bar penetration is analyzed for the soil with strain softening. The buoyancy effect on the bearing capacity factor is studied, which shown that the buoyancy mainly has an effect on the test soils with extremely low strength, but have little effect in the field tests. The characteristics of soil heave in the T-bar tests are analyzed to estimate soil sensitivities. To estimate the soil strength at shallow penetration depth, a relation to correct the T-bar bearing factors is built both on the soil with strain softening and no strain softening.

Water and salt migration mechanisms of saturated chloride clay during freeze-thaw in an open system

Water and salt migration mechanisms are of great significance for understanding the frost heave and thaw settlement of saline soils during freeze-thaw (F-T). In this study, unidirectional open-system F-T tests were conducted on saturated clay specimens with various chloride salt contents to investigate water and salt migration mechanisms. Relevant parameters, including temperature, unfrozen water content, bulk electrical conductivity, matric suction, and water intake volume, were measured continuously during testing. Besides, the water molecule mobility was obtained by the Nuclear Magnetic Resonance relaxometry tests to help understand the water and salt migration mechanisms. The test results indicated that the freezing front development was highly dependent on salt content. The matric suction gradient was found to be the driving force of water-salt migration, which was larger in specimens with lower salt content and led to more water intake. The migration of water and salt was asynchronous due to their different driving mechanisms during F-T. Specifically, salt migration was affected by both convection and diffusion, while water migration was primarily driven by convection. This phenomenon was also confirmed by the different patterns in water and salt redistributions after F-T. Meanwhile, pore water in the frozen specimens with different salinity and the same unfrozen water content was found to have the same water molecule mobility. Both the matric suction and water molecule mobility were dependent on unfrozen water content but independent on salt content. However, the salt content has a significant effect on the soil freezing point depression, which further affects the matric suction and water molecule mobility.

Centrifuge modeling of effectiveness of protective measures on existing tunnel subjected to nearby excavation

Various countermeasures are adopted to mitigate nearby excavation-induced deformations and internal forces of an existing tunnel. The effectiveness and function mechanism behind the measures are not yet fully understood. In this study, three three-dimensional centrifuge tests are carried out to investigate the responses of the tunnel and ground due to a nearby excavation in dry sand. Soil improvement below the excavation base (cement-sand mixing column) and grouting around the tunnel (grouted body) are considered in these tests. It is found that, due to the excavation, earth pressures on the tunnel right springline and right heel decrease, while these on the left shoulder and left springline increase. Mindlin Green’s function underestimates the reduction magnitude of earth pressure on the right springline, but overestimates the tunnel heave and soil heave at the excavation base. Soil improvement, due to its restriction effects on the diaphragm wall and ground, achieves a desirable effectiveness on mitigating the ground settlements, earth pressure changes around the tunnel, soil heave at excavation base, tunnel heave and bending moments. In comparison, grouting around the tunnel also exhibits a certain degree of effectiveness, which might resulting from its effects on strengthing the tunnel-soil interactions.