Expansive Shale Research Articles

Chemical Stabilization of Expansive Shale Using Natural Bagasse Fibers: A Case Study from Qena Area, Egypt

Chemical Stabilization of Expansive Shale Using Natural Bagasse Fibers: A Case Study from Qena Area, Egypt

Geotechnical modelling and subsurface analysis of complex underground structures using PLAXIS 3D

In this study, analysis of complicated underground structure of Horemheb tomb (KV57) at Luxor, Egypt by using the software PLAXIS 3D is adopted and the deformation that occurs in the body of the underground structure after applied the failure load detected; the failure loads are obtained from the series of laboratory tests. Then, the structure is modelled by using finite element code to perform accurate three-dimensional analysis of deformation and stability in complex geotechnical engineering and rock mechanics. These underground monumental structures have been analyzed by finite element method FEM to obtain the deformation that accrued into the structure and so beneath of the surface and calculated the effective stress, shear stress and horizontal displacements. In order to modeling requires the soil parameters obtained from laboratorial tests. In the analysis elastic–plastic Mohr–Coulomb model is used as material model. It involves five parameters namely, Young’s Modulus (E) and poison’s ratio (ν) for soil elasticity, friction angle (φ) and cohesion (c) for soil plasticity. To set up the boundary condition, the standard fixities option is used. As a result a full fixity at the base and free condition at the horizontal side of geometry are generated. Numerical Engineering analysis for Horemheb tomb (KV57) in the valley of kings at the west bank of Luxor was carried out through the following four main steps: (1) Evaluation of surrounding rocks (marl limestone and marl shale) by experimental research and Roclab program to obtain the Hoek Brown and Mohr- Coulomb fit classification criterion and rock mass standards in particular the global strength and deformation coefficient. Also to specify the main characteristics of the Esna Shale using different methods such as swelling test, swelling potential, swelling pressure, in addition, discussion of the role of the expansive Esna Shale in the deterioration of archaeological buildings and sites. (2) Quantitative and qualitative estimates of the relevant factors affecting the stability of the tomb, especially overloading, fixed, geographic, and dynamic. (3) Integrated 3D geotechnical modeling of the cemetery environment for stress and displacement analysis and identification of volumetric strains and plastic points using advanced symbols and programs such as PLAXIS 3D. (4) The rapeutic and retrofit policies and techniques and the fixed monitoring and control systems needed to strengthen and stabilize the cemetery, where the rock mass classification refers to the rock mass where KV57 is excavated and it is poor rocks. The mechanical behavior of the rocks is simulated by assuming a foundational model to soften the elastic stress of the flexible plastic that captures fragile failure and the mechanisms of progressive substrate failure. In addition, rock pillar treatments and ground support strategies are discussed. This article represents the second phase of the numerical analysis of KV57 using PLAXIS 3D.

Compaction Characteristics and Permeability of Expansive Shale Stabilized with Locally Produced Waste Materials.

Waste is available in an abundant form and goes to landfill without any use, creating threats to the environment. Recent and past studies have used different types of waste to stabilize soil and reduce environmental impacts. However, there is a lack of studies on the combined use of marble dust, rice-husk ash, and saw dust in expansive shale soil. The current study tries to overcome such a gap in the literature, studying the effect of marble dust, rice-husk ash, and saw dust on expansive shale’s compaction characteristics and permeability properties. According to unified soil classification and the AAHTO classification system, the geotechnical properties of natural soil are classified as clay of high plasticity (CH) and A-7-5. Several tests are performed in the laboratory to investigate the compaction characteristics and permeability properties of expansive shale. Moreover, permeability apparatus is used to investigate the permeability properties of soil. In addition, due to the accuracy of the apparatus, the conventional apparatus has been partly modified. The experimental results show that the addition of waste to the soil has significantly improved soil stabilization, increasing permeability and decreasing plasticity indexes. In addition, there is a gradual decrease in the dry density of soil and an increase in the permeability of stabilized soil. Based on the outcomes of the current study, it claims and concludes that these waste materials can be used as soil stabilizers or modifiers, instead of being dumped in landfill, which will provide a green, friendly, and sustainable environment. The current study recommends that future researchers use various wastes in the concrete and soil to improve their compaction and mechanical properties.

Numerical Modelling of Shallow Foundations on Expansive Shale: A Case Study of Jamshoro, Pakistan

This study analyzes expansive soil swelling under the shallow foundation using the Plaxis 2D FEM software. Under the impact of changing water conditions, expansive soil undergoes obvious volumetric changes, which often cause differential movements of the shallow foundations resting on it, which may lead to structural damage if no special precautions had been taken during the design process. In previous studies, the swelling of soil was simulated in Plaxis by applying the swelling potential with a positive volumetric strain, without considering water level changes, which proved to be not practical. This study demonstrates the time-dependent deformation (swelling) in expansive soil using the Plaxis 2D user-defined Swelling Rock Model in different soil and parametric conditions. The geotechnical properties of expansive shale were determined in the laboratory and by field testing, using parameters of the collected soil as input for the numerical model. Swelling of soil increased due to the increase of water level and decreased with the load. The heave was minimum in the center of the foundation (20 mm), attaining the maximum value at the corner (16 cm). The increase in the modulus of elasticity does not have much effect on soil swelling compared to soil settlement. The effect of matric suction-related changes on the swelling of soil due to the rise of the water table is not significant compared to the inherent soil swelling behaviour.

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.

Engineering Geology, History and Geography of the Pittsburgh, Pennsylvania Area

ABSTRACTThe City of Pittsburgh, PA is located west of the Appalachian Mountains in the Appalachian Plateaus Province. The relatively flat surface of the plateau is dissected by drainage from the three principal rivers of the region, the Allegheny, Monongahela, and Ohio. The formation of Pittsburgh’s three rivers and drainages has a long history dating back to before the Pleistocene Epoch, linked closely to the advance and retreat of continental glaciation.Western Pennsylvania is associated with the westernmost formation of the Appalachian Mountain chain with deformation in the form of a series of nearly flat-lying, gently warped Paleozoic sedimentary rocks. Rocks cropping out in the region range in age from Devonian to Permian. Pennsylvanian strata are dominated by thin cyclic sequences of sandstone, shale, claystone, coal, and limestone. Most of the geologic hazards present in the region include slope instability, expansive shales and slags, mine subsidence, acid mine drainage, pyritic acid rock and flooding. The region also has an abundance of natural resources including coal, natural gas, oil, salt, limestone, sand and gravel and water.Pittsburgh's strategic location helped shape westward expansion during the formation of the Nation, largely because of the rivers, which served as an inexpensive, yet efficient means of transportation. Infrastructure was always significant in Pittsburgh. However, the existing aging infrastructure are deteriorating. Today, Pittsburgh has transcended the legacy name, “Steel City” and has revitalized itself with nationally-recognized universities and medical centers and a resurgence in natural gas exploration. However, many environmental legacy issues still burden the area.

Integrating Geotechnical Investigation with Hydrological Modeling for Mitigation of Expansive Soil Hazards in Tabuk City, Saudi Arabia

Due to global climatic changes, flash floods are followed as a yearly disaster with high magnitude of influence. During the years 1981, 1988, 2010, 2012 and in January 2013, Tabuk city, northwest of Saudi Arabia suffered huge flash floods. These are major factors affecting on the swelling behavior of expansive Tabuk shale. The examined geotechnical properties of the surface and subsurface lithology of the sedimentary deposits distinguished Tabuk city into three zones. The expansive zone is spread in the middle and the non-expansive zones are distributed in the east and west of the city. The Watershed Modeling System (WMS) and Hydrologic Engineering Center (HEC-1) models were used to delineate and identify the drainage system and basin morphometry, where flash floods and accumulation of water might take place. Integration between geotechnical distribution maps of the expansion soil and surface hydrological data in terms of runoff maps was done. It has been identified the whereabouts the soils which have expansion characteristics and areas prone to flooding and surface runoff. They are helpful in defining the hazard zones map. Based on this map, it can be avoided constructions on the risk neighborhoods such as Al Qadsiyah, Al Maseif, Arrwdah, Al Nakhil and Al Rajhi. Also, it can suggest that the western side of Tabuk city is suitable for future urban extension. These results will help planners and citizens to create alternative development scenarios and determine their impact on the future urbanization patterns. Moreover, the direction of surface runoff flow or storm water discharge should be away from the expansion soil areas. Therefore, constructing dams on the outlet of the high-risk basins, south of Tabuk city is an important solution to control flash flood events, as well as increase groundwater recharge.

Role of smectite-rich shales in frequent foundation failures in southeast Nigeria

This paper investigated the geotechnical properties of smectite-rich shale, and its implications as foundation material. Ten expansive shale samples were collected from foundation materials at Akpugo in Nkanu West L.G.A. of Enugu State, southeast Nigeria. Samples were subjected to grading, Atterberg limits-cum-compaction tests, slake durability, specific gravity, permeability, undrained triaxial tests and x-ray diffraction scan. Fines and sand contents of the soil samples range from 51–97% and 3–49% respectively. Liquid limit, plastic limit and plasticity index have average values of 60.7, 19.1 and 43.3% respectively. Linear shrinkage and free swell showed average of 16.3% and 76%. These results are indicative of predominant clay soil with high plasticity, compressibility and water holding capacity. XRD scan established presence of smectite and illite clay minerals, confirming soil high plasticity, capable of causing instability in foundation soil. The shale achieved maximum dry density range between 1.79 and 1.94 kg/m3 at optimum moisture content range of 6.9–12.8%, indicating poor to fair foundation materials. The shale cohesion ranges from 15 to 30 kPa while the angle of friction ranges between 10° and 18°, signifying an average strength soil material. Samples slake durability index and specific gravity fall within 24–55% and 2.50–2.58 respectively, suggesting non-durable and weak soil. Permeability of the samples ranges between 7.36 ×10−6 and 4.77 ×10−8 cm/s which suggested low drainage capable of causing water-log at sites. Therefore, the shale could be generally classified as poor to fair foundation material, which on moisture influx experience reduction in strength due to deterioration of its constituent minerals, especially clay and cement materials during the lifespan of engineering structures. Authors therefore recommend modification of foundation soil, appropriate foundation design and good drainage control as ways of improving stability of engineering structures underlain by expansive shale.

Structural reform and petroleum (environment) regulations in the Northern Territory

The opportunity for onshore oil and gas development in the Northern Territory (NT) has grown exponentially in recent years, driven by the NT’s expansive shale gas resources in the McArthur Basin and elsewhere. Such resources provide many potential benefits to the territory’s economy, including job creation and clean, cost-effective energy generation opportunities. Critical to the successful development of the industry is a legitimate social licence to operate with the community, for which strong environmental regulation is a key enabling factor. Communities must be assured that oil and gas activities can provide ecologically sustainable development, and a transparent, evidence- and risk-based framework is the best way to achieve this. Following the NT Inquiry into Hydraulic Fracturing by Dr Allan Hawke in November 2014, and further review of the environmental assessment and approval processes in May 2015, the NT Government has implemented structural reform and developed contemporary outcome-focused Petroleum (Environment) Regulations to balance environmental protection with the economic development benefits offered by the onshore gas industry. Those objectives include that petroleum development in the NT: is consistent with the principles of ecologically sustainable development; reduces risks and impacts to levels that are as low as reasonably practicable and acceptable; ensures meaningful engagement with stakeholder; and, provides for transparency of decision-making and publication of approved environment management plans in full. This extended abstract provides an update of the reform of the regulatory framework, the regulatory objectives, the regulations by which they’re achieved, and the consultation process followed to gain wide stakeholder support. It will also highlight that strong regulations alone do not provide a robust regulatory framework, and the steps the NT Government is taking to achieve its objective. The regulations are planned to come into force in the third quarter of 2016. Meanwhile, a full review of the NT Petroleum Act and development of Petroleum (Resource Management) Regulations that takes into consideration the recommendations from the Hawke Inquiry into Hydraulic Fracturing in the NT is underway.

Efficiency of quicklime in reducing the swelling potential of pulverized expansive shale, Northern Jeddah, Saudi Arabia

Expansive shale has been found extensively all over the world, especially in tropical and sub-tropical regions. The ground heave that results from shale swelling potential is a multi-factorial phenomenon. Remarkably, the expansive shale of Saudi Arabia varies considerably due to variations in its ancient environmental climatic conditions. The studied shale of Bathan Formation at Al-Rehaili northeastern Jeddah is considered a problematic expansive material and classified as clayey shale of high plasticity (CH). Clay mineral species of these lacustrine sediments are composed mainly of smectite, kaolinite, and smectite-illite mixed layered. Exchangeable sodium percentage values of the Bathan Formation, northern Jeddah are very low. Addition of quicklime (up to 3 %) decreases consistency limits. The destructive effect of quicklime addition (up to 3 %) on the swelling potentiality of these clayey-rich sediments is due to the formation of highly swell ettringite. Mechanical properties, such as unconfined compression strength, have been improved due to the cementation effect of lime as well as the creation of new crystalline compounds such as calcium silicates and ettringite. Adding quicklime percent should not exceed 3 % to prevent increasing pH value and to avoid formation of ettringite which has higher ability to swell.

Swelling Characteristics of Saudi Tayma Shale and Consequential Impact on Light Structures

Expansive soils in Saudi Arabia have received wide attention in recent decades, following the rapid urbanization of rural and agricultural parts of the country. Tayma expansive shale inflicted serious damages to light structures, roads and boundary walls. This research is aimed at studying the engineering characteristics of the shale at this area including the basic geotechnical parameters as well as swelling behavior under oedometric loading conditions. The engineering properties were determined and compared to the local and international characterization charts. Mineralogy study using x-ray diffraction was conducted to investigate clay minerals present. The swell percent and the swelling pressure of the shale were investigated for samples prepared at different initial moisture contents and various dry densities. A close-up view of damages caused by the expansive shale in the town is highlighted and measures to reduce the risk of potential swelling distress for future constructions are presented.

Unsaturated characteristics of undisturbed expansive shale from Saudi Arabia

The aim of this paper is to evaluate the soil water characteristic curves (SWCC) of undisturbed expansive shale identified at different locations of Kingdom of Saudi Arabia. The SWCCs were evaluated for suction ranging from 0.5 to 400 MPa. Based on test results, all SWCCs reveal a bimodal curve indicating the presence of two distinct pore size distributions referred to as small and large micropores. Volume change measurements were performed to evaluate void ratio–suction relationships which confirmed the expansive nature of shale. Similarities between measured SWCCs and void ratio–suction relations developed for expansive shale originating from same geological formation suggests the impact of geological and environmental conditions on the unsaturated behavior of shale samples. Finally, a modified approach based on Mckeen’s classification methodology was proposed to assess the swelling potential using bimodal SWCCs. The modified approach was used to assess the relative contribution of different micropores on the swelling potential of shale.

Support of Structures in Expansive Shale Using Recycled Plastic Piles

Expansive soil formations can be found throughout the United States. When subjected to wetting, these formations have the potential to swell and exert large uplift forces on buildings and foundations. Lightly loaded structures, such as single family residences founded in areas of expansive soils, can be significantly damaged due to uplift movement from swelling actions. Designing an economical deep foundation that can resist uplift forces is critical to prevent damage to these structures. The current solutions to control uplift due to swelling soils, such as over-excavation and replacement of the expansive material or the use of drilled shafts can be costly. Piles made from recycled polymer materials could provide a solution. Due to a lower coefficient of friction along the interface of the soil-pile interface compared to traditional pile materials, solid recycled plastic piles can allow expansive soils to move nearly independently from the pile when wetted. This results in a much smaller magnitude of uplift force being transferred to the structure, which minimizes the risk of significant structural damage from excessive movements. This paper presents the results of research conducted on the use of recycled plastic piles in an expansive shale environment. The preliminary phase of the project involved the installation of six recycled plastic piles at a test site on the South Dakota School of Mines and Technology campus. Two of the piles were subjected to a full-scale compression load test in order to determine ultimate capacity. The remaining four piles were subjected to long-term monitoring of uplift movement during the course of the project. A concrete anchor was also installed at the test site for uplift monitoring. Data gathered during the field and laboratory testing was utilized in a non-linear soilstructure interaction model to predict the displacement behavior and internal stresses within a plastic pile and concrete anchor subjected to uplift forces from the swelling shale. While more research is needed to further understand the application for recycled plastic piles, the results from this research indicate that their use is a viable alternative for support of lightly loaded structures in expansive soil environments.

Influence of water chemical potential on the swelling of water sensitive materials

A coupled formulation based on non-equilibrium thermodynamics is derived to model the behaviour of expansive shales. Darcy's law is derived from the dissipation process by using standard arguments of non-equilibrium thermodynamics. The chemical potential of water has been included in classical Biot theory. Thus, the swelling effects due to hydration can be analysed. Finally, finite elements are used to solve the governing equations. The numerical results are consistent with swelling stress and strain responses observed experimentally. The deformations due to swelling are shown to be strongly affected by the choice of swelling parameter.

破壊特性を考慮した軽量コンクリートRC床版の押抜きせん断耐荷力評価手法

Load-carrying capacity of reinforced concrete (RC) members with lightweight concrete is lower in comparison with that of RC members with normal-weight concrete with the same compressive strength. This phenomenon depends on the fracture behavior of which the lightweight concrete is comparatively brittle to the normal-weight concrete. For the load-carrying capacity of RC members with the lightweight concrete, several reduction factors, which are applied to that of RC members with the normal-weight concrete, have been investigated by some researchers so far. The authors have been studied on the punching shear capacity of reinforced lightweight concrete slabs with the expansive shale aggregate. In the past studies conducted by the authors, the proposed reduction factors were constant values without a multiplicity of uses. In this paper, therefore, the applicable reduction factor to some kinds of lightweight concrete is derived in consideration with the fracture characteristics of the lightweight concrete. Consequently, the proposed method on punching shear capacity of the reinforced lightweight concrete slabs gives appropriate predicting values.

Measured and Estimated Suction Indices for Swelling Potential Classification

McKeen’s expansive soil classification methodology relies on a parameter referred to as the “total suction-water content index” for describing the slope of the soilwater characteristic curve on a semilog plot. The swelling potential of expansive soils is qualitatively classified (e.g., “low” or “high”) based on the magnitude of the total suction-water content index. This study examines the validity of using a “benchmark intercept simplification” for indirectly estimating the total suction-water content index when complete soilwater characteristic measurements are not available or economical. Suction indices estimated using the benchmark intercept simplification are compared with indices measured directly using the noncontact filter paper technique for 80 undisturbed expansive shale specimens from the Colorado Front Range Corridor. The results show that the suction-water content index is consistently overestimated using the benchmark simplification by amounts ranging from negligible to 50%, and averaging 23%. For 49 of the 80 specimens (61%), the estimated indices fall in different swelling potential categories than the measured indices. In 44 of the 49 cases (90%), the estimated indices fall in higher swelling potential categories than the measured indices. These discrepancies reflect potential errors that may arise from the use of the benchmark intercept simplification in classifying expansive soils.

Swelling Behaviour of Expansive Shales from the Middle Region of Saudi Arabia

Severe and widespread damage in residential buildings, sidewalks and pavements in various parts of the middle region of Saudi Arabia is caused by the development of heave and swelling pressure in the expansive shales in the region. This paper presents the problems and the geotechnical and physicochemical properties of the tested shales. The swelling potential was determined using various methods. Swell tests were conducted under different loading conditions and following different procedures to quantify the amount of vertical swell and swelling pressure. The conventional one-dimensional oedometer swell tests were performed using three different procedures, namely, free swell, constant volume swell and swell overburden. In addition, swell tests were performed in the stress path triaxial apparatus. Tests under different vertical stresses and confinements were conducted. Vertical swell and swelling pressure obtained from the various methods were compared. The reliability of the different methods for estimation of swelling potential is discussed.

Simplified heave prediction model for expansive shale : Dhowian, A W Geotech Test JV13, N4, Dec 1990, P323–333

Simplified heave prediction model for expansive shale : Dhowian, A W Geotech Test JV13, N4, Dec 1990, P323–333

Discussion on “Simplified Heave Prediction Model for Expansive Shale,” by A. W. Dhowian

Discussion on “Simplified Heave Prediction Model for Expansive Shale,” by A. W. Dhowian

Simplified Heave Prediction Model for Expansive Shale

Abstract A model is suggested to predict heave of expansive shale formation based on soil suction change. The model satisfactorily described the field volume change where the anticipated heave is compared with direct measurement obtained from an instrumented field station. The prediction is further simplified by introducing a model that only uses the moisture content variation to determine the amount of heave. Close agreement is observed between measured and model-predicted shale behavior. Application of this simplified model eliminates the difficulty of recovering an undisturbed specimen of shale which is highly weathered and friable as well as laminated.