Differential Heave Research Articles

Behavior of Slab-on-Grade Resting on Expansive Soil

Abstract This paper discusses a case study of a residential building in Benghazi that features slab-on-grade foundations supported by expansive soils. Although such structures are uncommon in the area, they can suffer serious damage due to volumetric changes in the soil caused by wetting and drying. The building has a total plan area of 200 m², with tie beams located 1.2 m above the formation level, and expansive soil used as backfill. After being moistened and lightly compacted, 100 mm thick concrete slabs were poured between the tie beams, resulting in varying slab sizes. Following a month of heavy rainfall, significant cracking—longitudinal, diagonal, and warping—occurred in the slabs due to uneven deformation from the expansive soil. The paper includes photographs of these deformations and cracks, along with an analysis of the geotechnical properties of the expansive soil, including its swelling and shrinking characteristics. It also employs an approach to predict the pressure exerted on the slabs due to differential heave.

Comparative Analysis of Foundation Systems in Expansive Soil: A Three-Dimensional Model Approach to Moisture Diffusion and Volume Changes

This study compares the performance of various foundation systems in expansive soils, such as mats, granular anchor piles, and concrete piles. Expansive soils experience volumetric changes due to moisture fluctuations, which can lead to structural damage. Abaqus software, in conjunction with the SCV approach, is used to analyze soil-foundation interactions. A custom subroutine enhances simulation accuracy by incorporating empirical data on unsaturated clay behavior, matric suction, and variations in effective stress. The method’s accuracy is validated by comparing simulation results to field and laboratory experiments. The findings indicate that increasing the applied load on mats decreases overall heave but increases the differential heave. Additionally, higher soil permeability dereases the differential heave of mats. Granular anchor piles outperform concrete piles by more than 50% in highly expansive soils, suggesting a preference for these foundations. This study provides insights into the behavior of expansive soils, which will assist engineers in designing resilient foundation systems for structures.

Effectiveness of Hybrid Geosynthetic Systems in Controlling Differential Heave in Flexible Pavements over Expansive Soils

The challenge of maintaining ride quality and serviceability in flexible pavements built over expansive soil deposits remains a critical concern for transportation agencies. These expansive subgrades exhibit swell-shrink behavior in response to moisture fluctuations, leading to differential heaving and subsequent costly maintenance. This paper explores the effectiveness of a Hybrid Geosynthetic Reinforcement System (HGRS)—a composite of geocell and geogrid—as a targeted mitigation strategy for differential heaving induced by expansive soils. A large-scale box test was designed to simulate a flexible pavement section, consisting solely of a base course layer and the underlying expansive subgrade. Four test conditions were investigated: an unreinforced control, a geocell-reinforced section, a geogrid-reinforced section, and an HGRS-reinforced section. Vertical displacements on the surface of the base course layer were longitudinally monitored and compared against the control. The results reveal that the use of geosynthetic reinforcements, and HGRS in particular, significantly mitigates both maximum surficial heave and differential swelling. Among the systems tested, flexible pavements featuring HGRS demonstrated the most effective performance in alleviating the challenges posed by expansive soil deposits.

Numerical simulation of replacement method to improve unsaturated expansive soil

AbstractIn this paper, a parametric study is done with various removal and replacement materials to study the effectiveness of the removal and replacement method on the wetting depth in the expansive soil and the amount of differential heave caused by climate conditions and common irrigation scenarios for the southern region of Syria. Soil suction changes and associated soil deformations are analyzed using finite element codes, VADOSE/W and SIGMA/W. The paper concludes that the optimum thickness for replacement with high permeability soil should be at least 1 m. In addition, it concludes that replacing soil with a permeability coefficient lower than the permeability coefficient of the site soil contributes to a 56% and 79% reduction in total and differential heave, respectively.

A State-of-the-Art Review and Numerical Study of Reinforced Expansive Soil with Granular Anchor Piles and Helical Piles

Expansive soils exist in many countries worldwide, and their characteristics make them exceedingly difficult to engineer. Due to its significant swelling and shrinkage characteristics, expansive soil defies many of the stabilization solutions available to engineers. Differential heave or settlement occurs when expansive soil swells or shrinks, causing severe damage to foundations, buildings, roadways, and retaining structures. In such soils, it is necessary to construct a foundation that avoids the adverse effects of settlement. As a result, building the structure’s foundations on expansive soil necessitates special consideration. Helical piles provide resistance to uplift in light structures. However, they may not fully stabilize foundations in expansive soils. A granular anchor pile is another anchor technique that may provide the necessary resistance to uplift in expansive soils using simpler methods. This review and numerical study investigate the fundamental foundation treatments for expansive soils and the behavior of granular anchors and helical piles. Results indicate that granular anchor piles performed better than helical piles for uplift and settlement performance. For heave performance, the granular anchor and helical piles perform nearly identically. Both achieve heave reductions greater than 90% when L/H > 1.5 and D = 0.6 m.

Centrifuge modelling of the effect of base slab stiffness on long-term heave and swell pressure

Long-term heave of basement slabs is a significant problem in cities with overconsolidated clay, such as London. There is a dearth of data to calibrate the methods commonly used by designers to predict heave displacement and swell pressure. This paper presents results from two centrifuge tests aimed at reproducing the phenomenon of long-term basement heave. Reduced scale models of rectangular basements with different slab thicknesses underlain by overconsolidated clay were tested, to investigate the effect of base slab stiffness on heave behaviour. The centrifuge tests provided measurements of the profiles of vertical displacement, bending moments in the slab and contact pressure at the slab–soil interface. This is the first geotechnical centrifuge study to provide simultaneous measurements of vertical displacement and swell pressures during long-term basement heave. Whereas the flexible basement underwent significant differential heave and almost complete relaxation of swell pressures, the stiff basement generated large swell pressures and consequently large bending stresses. These results confirm that the prediction of high heave pressures is a self-fulfilling prophecy: a basement slab with high stiffness will beget large swell pressures. The experimental measurements of swell pressure and heave were compared to predictions by a simplified non-linear method of heave calculation. The simplified non-linear method produced acceptable predictions of total heave.

Evaluating the Performance of Wicking Geotextile in Providing Drainage for Flexible Pavements Built over Expansive Soils

The longevity and performance of a pavement section depend on the characteristics of the subgrade soil. A majority of the pavements in North Texas, U.S., are constructed on expansive soils. The deterioration of the pavement performance because of rutting, cracking, and differential heaving is a regular phenomenon in the regions predominantly distributed with expansive soils. The pavements, particularly those built for low-volume traffic conditions, experience distress because of the high swelling and shrinkage characteristics of the underlying problematic soils. Geosynthetics have been traditionally used to improve such poor subgrades because of their many benefits, such as ease of installation, and ample mechanical and hydraulic properties. In the last decade, a newly available wicking geotextile, with a moisture redistribution capacity, has been developed to improve the performance of pavements constructed over expansive and frozen soils. In this study, small-scale laboratory and full-scale field studies were conducted to comprehend the wicking ability of this innovative geotextile in an expansive soil environment. Full-scale test sections were constructed with reclaimed asphalt pavement aggregate and traditional crushed stone aggregates in the base layer near North Texas. Details of the construction and instrumentation procedure are discussed in this paper. A comparative study between the performance of the pavement sections subjected to traffic loads and moisture intrusion was also performed. Furthermore, the rutting life of the sections, estimated using a linear elastic model, was compared and validated using the in situ data. The observations during the initial phase indicated that the wicking geotextile has the potential to improve the long-term pavement performance.

Polyurethane Grout Injection as Remedial Measure to Reduce Differential Heave in Pavement Sections Constructed over Expansive Soils

AbstractFlexible pavement sections constructed over expansive soil deposits often undergo significant damage due to volume changes in the underlying soil strata. When expansive soil deposits are co...

Full Scale Modeling of Footing Supported on Expansive Soil using Concrete Pile Anchor Foundation (CPAF).

Buildings constructions over expansive soils are exposed to many problems and cracks. The most damaging issues occur due to differential heave displacements, which cause excessive deformations to the overlying structure up to and beyond its serviceability limit state and, in the worst cases, its ultimate limit state. A site investigation is performed for the study area at Tabuk University, Kingdom of Saudi Arabia. The geotechnical soil properties and swelling characteristics were determined. Visual observations of samples obtained from drilled boreholes at study area revealed reddish brown to grey thinly laminated weathered shale followed by shale formation, the subsurface formation is classified (CH) according to USCS. The research study is aimed at measuring the contact pressure at field and studying the efficiency of concrete pile anchor foundation (CPAF) system in reducing heave of footings constructed on expansive soil. In the field, two full scales reinforced concrete footings with and without concrete anchor piles were constructed on top of the expansive shale. After construction of field prototypes, the test area is wetted for 64 days. Monitoring of the footing movement indicated that the footing upward movement using CPAF system caused a 62% less than the footing constructed directly on expansive shale.

Analysis of differential heaving distress in soil-structure interactions due to degradation of founding soil by chemical contaminations

In the process of rapid industrialization, land degradation is being observed in presence of chemical or other alterations in the natural soil. Expansive soil resulting from penetration of liquor in to the ground creating differential heaving stress in the foundation of the structures. Present paper deals a case study of distressed structure founding on the soil which is being contaminated with caustic liquor resulting from the process of manufacturing of Alumina. A reinforced cement tertiary thickener structure of Alumina plant (in India) rests on concentric columns got distress features in the form of upheaval of footings after four year of commissioning. The concrete and soil in the foundation area got contaminated with caustic liquor resulting in to the expansion of materials near to the foundation and creating differential heaving distress in the foundation and columns. This paper also deals the remedial measures and a methodology to make the structure stable and durable.

Evaluation of UAV–CRP Data for Monitoring Transportation Infrastructure Constructed over Expansive Soils

Application of unmanned aerial vehicles (UAVs) for civil infrastructure monitoring has gained impetus owing to the advancement of aerial platforms paralleled with the development of sophisticated sensors. Photogrammetry is the science of measuring distances from two or more images, and close-range photogrammetry (CRP) is a part of photogrammetry that involves calculating measurements of an object within a maximum distance of 305 m away from the inspecting sensors. Geotechnical problems including differential heaving and related cracking of expansive soils cause extensive damage to pavement infrastructure. Feasibility of using UAV–CRP technology in health monitoring of pavement infrastructure constructed over problematic soils has been comprehensively studied, and this paper presents an overview of these results. Pavement performance data including longitudinal and transverse slopes, as well as distress conditions such as pavement surface cracking, pothole formation, and rutting or excessive deformation, are monitored via UAV–CRP technology, and these data sets are comprehensively analysed. UAV–CRP-interpreted performance indicators showed a very good agreement with those obtained from traditional methods surveys and profiler studies. With the further research, the UAV–CRP technology will play an important engineering role in safe, inexpensive and comprehensive health monitoring of infrastructure built over problematic soil conditions.

ANALYSIS OF REPLACEMENT LAYER PROPERTIES AND ITS EFFECTS ON A TYPICAL BUILDING ON SWELLING CLAY

Extensive damage to the structures founded on expansive soils can be reduced using different techniques. Among these techniques, replacement of the expansive soil with a non-expansive soil is considered as one of the most popular. The main objective of the present work is to investigate the effectiveness of the replacement method under typical buildings. The finite element software ABAQUS was implemented in the present study in order to analyze the surface heave and the differential heave between the footings of a typical building. The present investigation considers the variation in replacement layer thickness, stiffness, and permeability. The soil-structure interaction was also considered. The present numerical results show a significant effect of the replacement soil thickness and permeability on the heave and differential heave. Reducing the replacement soil permeability results in significant reduction of the heave and the differential heave under different replacement soil thicknesses.

Dynamic analyses of buoyant leg storage and regasification platform: numerical studies

Present study highlights dynamic response behaviour of a buoyant leg storage and regasification platform (BLSRP), which is one of the recent developments in the domain of offshore structural engineering. This is a hybrid platform, which has combination of flexible and stiff degrees-of-freedom by virtue of design. A large deck is supported by six buoyant leg structures (BLS), which are connected to the deck by hinged joints. Hinged joints absorb rotational response of BLS units from transferring it to the deck, while translational responses are transferred like a monolithic structure. Detailed numerical investigations are carried out on a scaled model of BLSRP. Results of the conducted studies showed that heave response of the deck is lesser in comparison with that of the buoyant legs. The presence of roll and pitch responses of the deck, despite the hinged joint at each buoyant leg is due to the differential heave response that occurred from the dynamic tether tension variations. Response of the deck is less influenced by the wave action on buoyant legs due to the presence of hinged joints. Hinged joints isolate the deck from buoyant legs and thereby improve operational comfort and safety of the platform. It is also observed that maximum variation in tether tension is within the permissible limits. Geometric design of the buoyant legs, as attempted in the present study ensures a good recentering capability of the deck in all the translational degrees-of-freedom. Phase plots of both the deck and a typical buoyant leg confirm that the motion is stable and periodic.

Cryogenic disturbance and its impact on carbon fluxes in a subarctic heathland

Differential frost heave, along with the associated cryogenic disturbance that accompanies it, is an almost universal feature of arctic landscapes that potentially influences the fate of the soil carbon (C) stored in arctic soils. In this study, we quantify how gross ecosystem photosynthesis (GEP), soil respiration (Re) and the resulting net ecosystem exchange (NEE) vary in a patterned ground system (non-sorted circles) at plot-scale and whole-patterned ground scales in response to cryogenic disturbances (differential heave and soil surface disruption). We found that: (i) all studied non-sorted circles (n = 15) acted as net CO2 sources (positive NEE); (ii) GEP showed a weaker decrease than Re in response to increased cryogenic disturbance/decreased humus cover, indicating that undisturbed humus-covered sites are currently the main source of atmospheric CO2 in the studied system. Interestingly, Re fluxes normalized to C pools indicated that C is currently respired more rapidly at sites exposed to cryogenic disturbances; hence, higher NEE fluxes at less disturbed sites are likely an effect of a more slowly degrading but larger total pool that was built up in the past. Our results highlight the complex effects of cryogenic processes on the C cycle at various time scales.

Modeling biogeophysical interactions in nonsorted circles in the Low Arctic

We investigate biogeophysical processes that cause differential frost heave in nonsorted circles north of the Alaska's Brooks Range. The main objective is the development of a numerical thermo‐mechanical model of a nonsorted circle. The presented model includes mass, momentum and energy conservation laws for water, ice and soil. We applied this model to simulate differential frost heave at the Franklin Bluffs site and obtained a good quantitative agreement with measured dynamics of soil temperature, water content, and frost heave. For other locations such as at the Sagwon Hills and Howe Island sites we obtained qualitative agreement with frost‐heave measurements. Sensitivity analysis shows that the most active development of differential frost heave occurs for nonsorted circles within waterlogged areas, as observed in field measurements. For well drained sites, model results and field observations show that the differential frost heave is much smaller in magnitude comparing to that of the water‐logged sites. Sensitivity of the model to alternation of the vegetation cover shows that a strong heterogeneity in the vegetation cover promotes active development of the differential frost heave. For nonsorted circles with vegetation on top of the circle, the computed differential heave is less pronounced. The radius of the nonsorted circle influences the magnitude of the frost heave. The computed maximum frost heave in the center of the circle corresponds to 1–1.5 meter diameter nonsorted circles. For nonsorted circles with larger diameters, computed frost heave in the center of a circle is smaller compared to the heave at the circle circumference.

Involutions resulting from annual freeze–thaw cycles: a laboratory simulation based on observations in northeastern Japan

AbstractA pilot laboratory experiment using a reversed two‐layer soil model simulated small‐scale involutions formed in a seasonal frost environment during the last glacial period. At the modelled site, the interface between the upper aeolian sandy loam and the lower volcanic pumice constitutes small‐scale involutions that display upward‐extending tapered projections and downward‐extending round hollows. Two scale‐reduced laboratory models were subjected to three accelerated annual freeze–thaw cycles with monitoring of frost heave, soil temperature, moisture and pressure. Ice segregation near the layer interface induces upheaving of coarse pumice grains on freezing and earlier settlement of mobilised loam on thawing, resulting in deformation of the interface. A reconstructed 3‐D interface displays mounds and depressions with a diameter of 15–20 cm and a height increasing with freeze– thaw alternations. The experimental results imply that the repetition of differential heave and soft‐loam settlement promotes decimetre‐scale involutions in near‐saturated soils subject to deep seasonal frost penetration. Copyright © 2007 John Wiley & Sons, Ltd.

Steeply Dipping Heaving Bedrock, Colorado: Part 3 Environmental Controls and Heaving Processes

This paper examines the environmental processes and mechanisms that govern differential heaving in steeply dipping claystone bedrock near Denver, Colorado. Three potential heave mechanisms and causal processes were evaluated: (1) rebound expansion, from reduced overburden stress; (2) expansive gypsum-crystal precipitation, from oxidation of pyrite; and (3) swelling of clay minerals, from increased ground moisture. First, we documented the effect of short-term changes in overburden stress, atmospheric exposure, and ground moisture on bedrock at various field sites and in laboratory samples. Second, we documented differential heaving episodes in outcrops and at construction and developed sites. We found that unloading and exposure of the bedrock in construction-cut areas are essentially one-time processes that result in drying and desiccation of the near-surface bedrock, with no visible heaving response. In contrast, wetting produces a distinct swelling response in the claystone strata, and it may occur repeatedly as natural precipitation or from lawn irrigation. We documented 2.5 to 7.5 cm (1 to 3 in.) of differential heaving in 24 hours triggered by sudden infiltration of water at the exposed ground surface in outcrops and at construction sites. From these results, we interpret that rebound and pyrite weathering, both of which figure strongly into the long-term geologic evolution of the geologic framework, do not appear to be major heave mechanisms at these excavation depths. Heaving of the claystone takes two forms: (1) hydration swelling of dipping bentonitic beds or zones, and (2) hydration swelling within bedrock blocks accommodated by lateral, thrust-shear movements along pre-existing bedding and fracture planes.

Evolution of Pavement Winter Roughness

The functional service level of roads is quantified in terms of roughness. This parameter considers every road surface defect that causes passenger vehicle discomfort. Roughness is measured by a quality index, the international roughness index (IRI). Roughness gives an overall appreciation of road profile quality without, however, permitting a deeper analysis. The overall value of the IRI does not discriminate between the two main factors responsible for winter deterioration of roughness: the subgrade differential heave and crack heaving (winter tenting). Differential heave is the result of variability in frost susceptibility of subgrade. This phenomenon can be detected by isolating the long wavelengths produced at the road surface from the longitudinal profile. Crack heaving is a superficial phenomenon greatly influenced by the application of deicing salts. By isolating the short wavelengths from the profile, it is possible to highlight the influence of this phenomenon on deterioration. The goal of this research is to establish, with the use of a filtering technique of road profile, the contribution of these two main factors to winter deterioration of roughness on five road sections in the Quebec City, Canada, area. This study will then allow for the development of a tool to determine the dominant factor for longitudinal profile deterioration and therefore the use of the best technique to rehabilitate roads.

Evolution of Pavement Winter Roughness

The functional service level of roads is quantified in terms of roughness. This parameter considers every road surface defect that causes passenger vehicle discomfort. Roughness is measured by a quality index, the international roughness index (IRI). Roughness gives an overall appreciation of road profile quality without, however, permitting a deeper analysis. The overall value of the IRI does not discriminate between the two main factors responsible for winter deterioration of roughness: the subgrade differential heave and crack heaving (winter tenting). Differential heave is the result of variability in frost susceptibility of subgrade. This phenomenon can be detected by isolating the long wavelengths produced at the road surface from the longitudinal profile. Crack heaving is a superficial phenomenon greatly influenced by the application of deicing salts. By isolating the short wavelengths from the profile, it is possible to highlight the influence of this phenomenon on deterioration. The goal of this research is to establish, with the use of a filtering technique of road profile, the contribution of these two main factors to winter deterioration of roughness on five road sections in the Quebec City, Canada, area. This study will then allow for the development of a tool to determine the dominant factor for longitudinal profile deterioration and therefore the use of the best technique to rehabilitate roads.

Case History of Damage to a School Building Caused by Differentially Heaving Bedrock

This case study considers the question of whether settlement or heave is the principal cause of damage to a school building near Denver. The building, which was underlain by engineered fill in the center and shallow claystone bedrock beneath the outer wings, experienced progressive deformation and significant damage during a 15-year period. With several millions of dollars of rebuilding costs at risk, the most likely cause of failure needed to be ascertained to arrive at an optimum mitigation solution. The investigation described herein considers the regional geology and its known effect on various types of engineered structures in terms of characteristic damage patterns. The focus progressively narrows to concentrate on the geology and damage patterns of the local area and the site. The findings indicate that the major cause of damage to the building is associated with differential heaving of steeply dipping, expansive bedrock layers. This conclusion was adopted as a basis for subsequent remedial planning and design.