Surface Heave Research Articles

Validation of Photogrammetric Monitoring for TrenchlessConstruction Applications

A primary concern of owners specifying trenchless installation and rehabilitation methods are surface movements during construction. Surface heave or settlement can occur as a result of contractor methodology, design, or geotechnical conditions. Performing quality assurance during and after construction provides owners with an understanding of what surface movements have occurred and if remedial action may be required. Traditional methods utilized to measure ground surface movements include surveying triangulation, geometric leveling, and global positioning system (GPS) surveying. This paper presents a procedure to utilize photogrammetry in the measuring of ground movements and examines its precision and accuracy in simulated field conditions. Utilizing consumer-grade digital single lens reflex (SLR) cameras, photogrammetry does not require highly trained personnel, takes less time, and costs less money than traditional methods. Accuracy is determined by comparing measurements taken with photogrammetry to those taken with traditional rod and level. The results are compiled and analyzed to determine the accuracy and precision of photogrammetry in measuring ground movements.

Estimation of Reservoir Hydraulic Property From Surface Heave Monitoring During Subsurface Fluid Injection

Summary Subsurface fluid injections, such as wastewater disposal, waterflooding, and CO2 sequestration, cause reservoir dilation. The reservoir dilation induces displacements in the overburden extending up to the ground surface and resulting in surface heave. Previous studies have illustrated that it is possible to delineate the extent of the reservoir dilation from the surface heave measurement using an inverse technique. This paper proposes that the inverse technique can be extended to estimate the growth and propagation of the reservoir dilation during the fluid injection if the surface heave is monitored continually. Then, the reservoir pressure distribution and hydraulic properties could also possibly be determined from the fluid-flow equations. The results obtained from the proposed technique were compared with those obtained from a fully-coupled finite element (FE) simulation of a fluid injection problem. It was found that the numerical tool could be successfully adopted to estimate an approximate value of the reservoir permeability.

Geomechanical modeling for CO2 Storage in Wabamun Lake Area of Alberta, Canada

Abstract Based on experience gained from existing sequestration pilot projects and enhanced oil recovery practices, geologic storage is a technically viable means to significantly reduce anthropogenic emissions of CO2. During CO2 injection, increasing pore pressure and temperature reduction create geomechanical deformation of both the reservoir and surrounding rocks. One of the most important concerns with respect to the long term CO2 storage is that stress changes caused by injection could lead to formation fracturing or reactivation of fracture networks and fault movements which could potentially provide pathways for CO2 leakage through previously impermeable rocks. The cumulative CO2 emission from power plants located in Wabamun lake area in central Alberta, Canada reaches 30 Mt/year. Nisku geological formation located in Wabamun lake area was chosen as storage target based on storage capacity, expected ease of injectivity, leakage risks and interference with current petroleum production in the area. In order to determine whether the post-injection stress changes affect the viability of this target formation to act as an effective storage unit, the geomechanical assessment model of the formation has been developed, which couples the flow model and geomechanical model covering all layers from the basement to the surface. This work was a part of a comprehensive feasibility study of large scale CO2 storage potential in the Wabamun area, called the Wabamun Area CO2 Sequestration Project (WASP). The model used rock mechanical properties, reservoir characterization and flow properties of the Nisku provided by extensive work in other teams of the WASP project. The present modeling work focused on evaluation of a single well injecting 1 Mt/year for 50 years, followed by simulation of 50 years of shut-in. The pressure and stress variations were modeled during and after CO2 injection utilizing geomechanical software, GEOSIM, commercial code of Taurus Ltd. In order to increase the well injectivity, the case of allowing fracture initiation and propagation in Nisku was considered. The results show that injection above the fracture pressure will have the potential to increase the well injectivity (to at least 2 Mt/year) but also create the possibility of fracturing the caprock. The possible upward fracture propagation strongly depends on the caprock stress state and mechanical properties. However, the results of the simulation of vertical propagation have been obtained under the most unfavorable assumption of constant minimum stress gradient and are only preliminary. Since injected CO2’s temperature is considerably lower than the formation temperature, thermal effects were incorporated into the models. Decreasing temperature due to CO2 injection will result in stress reduction and smaller surface deformations compared to the isothermal model. Thermal effects of cold CO2 injection will also reduce the fracture (injection) pressure and enhance the horizontal fracture propagation through Nisku. CO2 injection in the Nisku zone is not likely to cause any significant surface heave and is not likely to have any environmental impact associated with surface deformations. Surface deformation data can be used in conjunction with seismic measurements to validate mechanical properties of Nisku and overlying layers. It also can help to plan for the location of the instrumentation and surface monitoring. Given the best estimates of cohesion and friction angle, the probability of reaching shear failure in Nisku or in the caprock is low. However, the likelihood of fracturing due to thermal effects is high. The importance of modeling of thermal effects in CO2 storage is the most important contribution. The results of this study are in agreement with our research on CO2 storage in Ohio River Valley.

Application of High Energy Dynamic Compaction in Coastal Reclamation Areas

High energy dynamic compaction (HEDC) is adopted in a coastal reclamation area because the grain size of backfilled soil mostly ranges between 20 cm and 100 cm. The in situ tests for evaluating the effectiveness of HEDC were performed on the backfilled soil ground. The crater depth per drop and the whole test zone elevations before and after HEDC were measured and analyzed. Dynamic penetration tests and spectral analysis of surface wave (SASW) tests were used for investigating the improvement depth. Furthermore, the allowable bearing capacity of HEDC treated ground was determined based on the results of plate-load tests. It was found that HEDC did not cause the ground surface heave during construction, and was more effective than low energy dynamic compaction (LEDC) in terms of applied energy utilization. Based on the test results, the improvement depth of HEDC at this site was not less than 14 m, and there was no obvious weak layer within the range of improvement depth. The allowable bearing capacities were larger than 160 kPa. The investigation results indicate that the HEDC technique is an effective way for improving backfilled coarse-grained soil in coastal reclamation areas. This technique helps to achieve both greater improvement depths and higher ground bearing capacities as compared with LEDC.

Field studies of variation scales of gravitational capillary waves and near-water wind in the Black Sea shelf area

In this study we present the results of data processing from the 2004 Gelendzhik Bay expedition on the Akvanavt research vessel. The data were processed using the method of wavelet analysis. We found an emerging kilometer-scale variation in the surface heaving and near-water wave over the shelf area. This effect was shown to be possibly caused by the inhomogeneity of current in the depth-drop area.

Relationship between ground ice and solifluction: Field measurements in the Daisetsu Mountains, northern Japan

AbstractSoil temperature, surface heave and downslope movements were monitored continuously for one year (1998–99) within a solifluction lobe developed on seasonally frozen ground in the Daisetsu Mountains, northern Japan. Observations were also made of soil moisture and ice segregation. Seasonal freeze‐thaw cycles produced both frost creep and gelifluction. In layers shallower than 60 cm, ice segregation during the freezing season induced seasonal frost heave, and ice melt at the same depths during the thaw season promoted gelifluction as well as seasonal frost creep. At greater depths, gelifluction did not occur even when the thaw plane reached the ice‐rich layers. The results at the study site demonstrate that segregated ice plays an important role in gelifluction, but only at shallower depths. Copyright © 2010 John Wiley & Sons, Ltd.

Interplay between Field Measurements and Soil Behavior for Capturing Supported Excavation Response

Instruments are installed during the construction of urban excavations to monitor ground response at discrete locations to various construction activities, to verify design assumptions and to effectively apply the observational approach. Inverse analysis approaches are often used to develop improved soil models suitable for representing soil response during excavation from these measurements. We propose that through the integration of inverse analysis and instrument measurements, it is possible to provide information on excavation performance at locations where no instrumentation is available. Therefore, this study examines the relationship between various instruments typically used on an excavation project and the quality of information that can be extracted for excavation modeling. A synthetically generated set of instrument measurements that include inclinometers, surface settlement points, extensometers, heave gauges, piezometers, and strain gauges, using an idealized soil profile are initially used. The analyses show that in addition to the measurements of lateral wall deflections and surface settlement, inclinometers placed some distance behind the wall and measured forces in the struts significantly improve the quality of the extracted soil behavior. These findings are further demonstrated with a well instrumented deep excavation case study in Taipei. The inclinometers at the wall and at farther distance from the wall are used to extract the soil behavior. The extracted soil model used in a numerical analysis provides a good prediction of excavation behavior elsewhere around the excavation including surface settlements.

How far does surface heave propagate? A discussion on analytical and numerical modeling of the surface heave induced by subsurface fluid injection

Reservoir dilations occur due to variety of subsurface injection operations including waste disposal, waterflooding, steam injection, CO2 sequestration and aquifer storage recovery. These reservoir dilations propagate to the surrounding formations and extend up to the ground surface resulting in surface heaves. This paper discusses modeling of the surface heave by applying both analytical and numerical methods. Results of the study demonstrate that the lateral extent of a finite element model has a direct impact on the surface heave profile and if the lateral boundaries are too close to the line of symmetry, there will be significant errors in the finite element results. This paper proposes a rapid way of estimating a sufficient lateral extent for the finite element model by using a new chart. The chart contains a family of curves, which can be used to estimate the surface heave propagation distance under various injection depths, injection periods and soil properties.

New Mechanism-Based Design Approach for Spudcan Foundations on Single Layer Clay

Spudcan foundations for offshore mobile drilling rigs are large saucer-shaped foundations that can penetrate several tens of meters into soft sediments. The penetration depth is typically predicted by considering a wished-in-place foundation at different depths and following traditional bearing capacity approaches to assess the depth at which the estimated capacity matches the applied loading. However, the geometry of the spudcan and its progressive mode of penetration lead to soil failure mechanisms that differ markedly from those relevant to onshore practice. This paper presents a new rational design approach for assessing spudcan penetration in single layer clays based on a study combining centrifuge model testing and large deformation finite-element (FE) analysis. The design approach takes account of the evolving failure mechanisms in the soil, which start with cavity formation and surface heave at shallow penetration, gradually transforming to backflow of soil over the spudcan. A detailed FE parametric study has explored the relevant range of normalized strength, strength nonhomogeneity, and spudcan base roughness, with results validated against centrifuge model test data. The penetration response curves are presented in terms of profiles of bearing capacity factors, forming nondimensional design charts along with simplified expressions for convenient use in practice. Comparisons with approaches suggested in the SNAME design code suggest an urgent need to update current practice.

Effect of Surface Heave on Response of Partially Embedded Pipelines on Clay

The as-laid embedment of an on-bottom pipeline strongly influences the resulting thermal insulation, and the resistance to subsequent axial and lateral movement of the pipeline. Reliable assessment of these parameters is essential for the design of offshore pipelines. Static vertical penetration of a pipe into a soft clay seabed—which can be modeled as an undrained process—causes heave of soil on each side of the pipeline. The heaved soil contributes to the vertical penetration resistance and the horizontal capacity. This paper describes a series of large deformation finite-element analyses of pipe penetration, supported by a simple analytical assessment of the heave process. The conventional bearing capacity approach to the analysis of pipe penetration is reviewed, and modifications for the effects of soil weight and heave are presented. It is shown that in soft soil conditions—which are typical for deep water—the soil self-weight contributes a significant portion of the vertical penetration resistance a...

Detection of surface deformation related with CO2 injection by DInSAR at In Salah, Algeria

Surface deformation around CO2 injection wells at In Salah, Algeria was analyzed by satellite-borne SAR data. The surface heave rate up to 7 mm/year was detected around all of the three injection wells. The analysis of the deformation series has revealed that each injection well has different deformation history. The surface heave pattern shows a NW-SE trending elongation which is the direction of the anticline axis, suggesting certain relationship between the structural feature and the distribution of injected CO2. This technique will hopefully provide us with a powerful and a cost-effective tool for monitoring of behaviors of the injected CO2.

Numerical Study of the Effect of Foundation Size for a Wide Range of Sands

This paper presents a numerical investigation of the effect of foundation size on the response of shallow circular foundations on siliceous and calcareous sands. The study is based on the predictive capabilities of the MIT-S1 soil model for simulating both the compression and shear behaviors of natural sands over a wide range of densities, K0 values and confining pressures. The paper highlights the variations in the deformation mechanisms for the siliceous and calcareous sands cases. The assessment of the bearing capacity factor, Nγ, is examined, showing a dramatic decrease in the values with increasing foundation size for the case of footings on calcareous sands, eventually converging to a terminal Nγ value. At this stage the sand resistance is insensitive to variations in initial density and foundation size because the sand tends to loose its initial characteristics due to grain crushing, leading the material rapidly toward ultimate conditions. In the silicious sand case, it is found that, eventually, for extremely large footing diameters, the deformation mechanism progresses toward a punching shear mechanism, rather than the classical rapture pattern accompanied by surface heave as employed in current bearing capacity equations. A dimensional transition between the failure mechanisms can clearly be defined, referred to as a “critical size” in the Nγ–D relationship.

Model Test on Inundation Swelling Deformation of Expansive Soil Foundation

AbstractA large model test of 10 m ×2.5 m ×4.1 m in length, width and height was carried out to study the swelling deformation and water content of expansive soil foundation under deep inundation. The water content, surface heave and deep heave were measured in the test. It is indicated that (1) the swelling deformation and water content are influenced by the dry density of soil and the foundation pressure; (2) the water content-time curves can be divided into initial, sudden and steady phases; (3) the larger the overburden pressure is, the less the surface heave is, so the swelling deformation decreases with the increase of overburden pressure; (4) the deformation characteristics of expansive soil foundation can be divided into compression, no deformation, swelling deformation or the composite; (5) the depth of swelling deformation is related to the pressure, size and shape of foundation.

Uplift Mechanisms of Pipes Buried in Sand

Reliable design against upheaval buckling of offshore pipelines requires the uplift response to be predicted. This paper describes a model-scale investigation into the mechanisms by which uplift resistance is mobilized in silica sand, and illustrates how the observed mechanisms are captured in prediction models. A novel image-based deformation measurement technique has been used. The results show that peak uplift resistance is mobilized through the formation of an inverted trapezoidal block, bounded by a pair of distributed shear zones. The inclination of the shear zone is dependent on the soil density, and therefore dilatancy. After peak resistance, shear bands form and softening behavior is observed. At large pipe displacements, either a combination of a vertical sliding block mechanism and a flow-around mechanism near the pipe or a localized flow-around mechanism without surface heave is observed, depending on the soil density and particle size.

Surface Heave Induced by Steam Stimulation in Oil Sand Reservoirs

Abstract Steam stimulation is one of the viable methods to extract heavy oil from oil sand reservoirs in Alberta. In this thermal process, steam is injected into the oil sand reservoir. The oil sand formation expands due to an increase in pore pressure and thermal heating. This expansion results in an upward movement of the overburden, and thus, heaving of the free ground surface. This paper proposes an analytical method to estimate the surface heave induced by steam injection. The method was used to investigate the surface heave profiles under horizontal well injection. It was found that the surface heave profile is governed by the mass and heat transfer and distribution within the oil sand reservoir. The effect of the increase in pore pressure (or decrease in net overburden stress) on the surface heave is also compared to that due to the thermal expansion of the oil sand. The paper also discusses the limitations on the use of surface heave monuments and tiltmeters in monitoring the thermal recovery process. Introduction Thermal recovery processes such as cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD) involve large volume fluid and steam injection into oil sand reservoirs. Steam injection produces a dilatation of the oil sand reservoir due to an increase in pore pressure and temperature of the reservoir. The overburden containing the reservoir responds to the steam injection by upward heaving of the free ground surface. Surface heave of up to 20 cm has been recorded(1). The profile of the surface heave reflects the distribution of the injected steam within the oil sand formation. Monitoring the surface heave evolution during the steaming operation may be used as an inverse method of monitoring the steam injection operation. This paper presents an analytical method to determine the surface heave profile induced by steam stimulation for a horizontal well. Parametric studies were conducted to investigate the important factors contributing to the surface heave profile. Problem Statement This study considers a steam stimulation operation using a horizontal well. Steam is injected into a horizontal well installed within an oil sand formation of finite thickness (Figure 1). Since the overburden serves as a competent hydraulic barrier to the fluid upward migration, it is assumed that the injected steam is contained within the oil sand reservoir, which results in an expansion of the reservoir. Thus, steam injection using a horizontal well can be treated as a two-dimensional plane strain problem. Figure 1 illustrates the problem statement. The objective of the exercise is to determine the surface heave profile as a function of the amount of steam injected into the horizontal well. Methodology Steam stimulation is a complex thermal hydraulic mechanical multiphase flow process. Determination of injected fluid distribution within the reservoir is not trivial. Since the shale overburden serves as a competent hydraulic barrier to the fluid upward migration, the geomechanical responses in the overburden are governed by the expansion pattern of the oil sand reservoir due to steam stimulation.

A case study for mapping of spatial distribution of free surface heave in alluvial soils (Yalova, Turkey) by using GIS software

A procedure for producing a surface heave map using GIS package in clayey alluvial soils is proposed. An active zone was first defined, and the layers in the active zone were subdivided according to their swelling characteristics. The free surface heave values for each cell of the digitized map of the study area were calculated by using the available equation in the literature, and a spatial distribution map was then constructed interpolating the data belonging to each borehole location. Soils having a high swelling capacity are widely distributed in the study area, and will cause serious heave problems on light structures. Clayey soils in the study area have generally moderate–very high swelling potentials, and swell pressures in many locations are much higher (up to 98 kPa) for low-rise structures. Moreover, differential movements sourced from surface heave are also expected in many locations. It was calculated that the minimum expected heave was 0.00 cm while the maximum was 12.24 cm, indicating “ very severe” differential movement. The results obtained in this paper can be used as basic data to assist surface heave hazard management and land use planning. The information derived from this study also has a special importance for assessing the probable deformations on intended light construction applications in Yalova city. The methods used in this study will be valid for generalized planning and assessment purposes; although they may be less useful on the site-specific scale, where local geology and geographic heterogeneities may prevail.

Casing Impairment Induced by Shear Slip Along a Weak Layer in Shale Due to Fluid (Steam) Injection

Abstract Thermal recovery processes such as cyclic steam stimulation and steam assisted gravity drainage involve large volume fluid and steam injection into oil sand reservoirs. Thermal expansion and dilatation of oil sand formation causes horizontal and vertical displacements in the overburden. These deformations may not exert detrimental effects on casings and facilities if the deformation properties of the overburden are homogeneous without drastic local variation along depth. However, if there exists some natural (clay seams) or induced weak layers (swollen and softened shale layer), shear slip could develop along these discontinuities, thereby impairing the nearby casings and facilities. This paper develops a semi-empirical analytical method for estimating the relative shear slip along a weak layer in shale due to fluid and steam injection. The magnitude of slip depends on the volume and distribution of fluid and steam injection, and the extent and location of the weak layer. Calculated results demonstrate that the shear slip along the weak layer could impose concerns regarding the steaming strategy and environmental protection. Introduction Heavy oil and bitumen are major energy resources in Canada, and have become a major focus for the oil and gas industry. The heavy oil deposits in Canada may contain about 30% of the world's recoverable oil(1). The challenge in developing this resource is the difficulty in recovering these highly viscous substances. Steam stimulation is one of the viable thermal recovery methods to extract bitumen from the oil sand ores buried in deep overburden. In this steam-based recovery method, a large volume of steam at high temperatures and pressures (300 °C and 10 MPa) is injected into the oil sand formation at depths of 400 ? 450 m through wells placed in rows(2, 3). Steam injection produces dilatation of an oil sand reservoir due to an increase in pore pressure and thermal expansion of the reservoir. Because oil sands are dense, uncemented sands, the resulting deformation induced during the recovery process could be excessive and detrimental to surface and subsurface facilities(4). Surface heave of up to 30 cm has been recorded(5) in some facilities. Overlaying the oil sand formation are low-permeability clay shales forming essentially an impermeable barrier to upward migration of the injected fluid. Weak layers such as clay seams and natural horizontal fissures are commonly found in these shale formations(6, 7). These weak layers retain no tensile strength or low residual strength. Wong and Chau(8) investigated the potential of propagation of these weak fractures in shale due to steam injection. They found that the propensity for occurrence of tensile and shear fracturing in discontinuous shale is low because the high overburden stresses are sufficient to limit the fracture initiation process. However, one of the potential geomechanics-related problems is if shear slip occurs along these weak layers due to fluid injection into the oil sand reservoir leading to casing impairment or rupture. The main objectives of this study are to:investigate if such a slip mechanism is admissible in natural weak layers confined by the competent overburden shale;

Effects of base geogrid on geocell-reinforced foundation beds

The effect of a base geogrid layer below the geocell mattress in sand, sand overlying soft clay, and soft clay foundation beds has been studied using a series of laboratory scale load tests. A rigid circular model footing was used to apply static monotonic loading on the foundation beds with and without geocell reinforcement. The model test results show that the provision of an additional layer of planar geogrid at the base of the geocell mattress further increases the performance of the footing in terms of bearing capacity and reduction in surface heave of the foundation bed. It is also observed that the beneficial effect of the base geogrid layer becomes negligible with increasing height of the geocell mattress beyond the influence of the depth of the footing. Strain measurements in the base geogrid layer indicate that it is more effective with the limited heights of the geocell mattress. The earth pressure cells embedded in the subgrade soil provide evidence that when the base geogrid is provided below the geocell mattress, the footing pressure is distributed more uniformly over an extended area.

Chromite Ore Processing Residue (COPR): Hazardous Contaminated Soil or Solid Waste?

Abstract Chromite ore processing residue (COPR), which contains hexavalent chromium (Cr6+) at concentrations typically in the range of thousands of milligrams/kilograms, was deposited over a timeframe of 50 years as fill at a site referred to as SA7 in New Jersey. Significant surface heaving associated with COPR weathering-induced mineralogical expansion has been observed at the site over time. The current site owner is being required to remediate the site to mitigate both human health risks associated with the Cr6+ and site redevelopment problems associated with COPR heave. The owner is presently required to remediate the COPR by excavation and off-site disposal at a licensed hazardous waste landfill. This is a very expensive remediation option, one that may not be financially sustainable at other COPR impacted sites. The owner has undertaken a major investigation to better characterize the nature of COPR and to develop on-site treatment technologies to reduce Cr6+ concentrations and mitigate COPR heave potential. As one part of the investigation, the characteristics of COPR were evaluated with respect to the definitions of hazardous contaminated soil and hazardous solid waste under the toxicity characteristic waste provisions of the U.S. Resource Conservation and Recovery Act (RCRA). Remediation clean-up standards, and thus the potential costs and applicable methods associated with site remediation, under these two definitions are significantly different. This paper explains these differences and evaluates the COPR for conformance with each definition. This evaluation includes comparison of sampling, logging, and laboratory testing techniques for COPR compared to soil, geotechnical parameter comparisons, and mineralogical and total metals comparisons. Based on these comparisons, the authors conclude that COPR should classify as a hazardous contaminated soil from both regulatory and scientific perspectives. The bases for this conclusion are provided in the paper. The methodology presented herein to evaluate COPR classification may have applicability to other contaminated soil-like media from industrial processes that are potentially subject to the requirements of RCRA hazardous waste regulations or similar regulations in other countries.

Numerical characterization of surface heave associated with horizontal directional drilling

This paper presents the implementation of an artificial neural network to predict surface heave resulting from shallow subsurface utility installations conducted with horizontal directional drilling. Data gathered from a full factorial field experimentation examining the effects of drilling techniques is utilized in the network development, with the attempt to understand the relationship between construction techniques and resulting surface heave. The developed model is compared to a multivariate linear regression analysis conducted on the raw data, and a sensitivity analysis utilizing the trained network connection weights is conducted to determine which factor has the greatest effect on surface heave development. Further examination of the behavior of the system is provided through a trend analysis which studied the effect of each drilling factor on the predicted surface heave. The results indicate that a neural network would adequately model the relationship between drilling techniques and the resulting surface heave.