Showing papers in "International Journal of Geotechnical Engineering in 2018"

Experimental and phenomenological study of the effects of adding shredded tire chips on geotechnical properties of peat

Abstract: Due to the high values of organic and water contents, and other poor geotechnical properties of peats, it is essential to stabilise peat deposits. Moreover, in recent decades, accumulation of waste tires has caused myriad environmental problems all around the world. To tackle both issues, a reasonable remedy is to use scrap tires for stabilisation of peat soils. Since some of geotechnical properties of tire stabilised peats have been not reported yet, the aim of this study is to investigate the effects of adding different weight percentages of shredded tire chips (0, 5, 10, 15 and 20%) along with constant amount of sand (400 kg/m3) on some of geotechnical properties of stabilised peat such as unconfined compressive strength (UCS), secant modulus (Es), failure strain (ef), brittleness index (IB), deformability indexes (ID), resilient modulus (Mr), bulk modulus (K), shear modulus (G), cohesion (C) and angle of internal friction (φ) using UCS and direct shear tests. Moreover, to chemically characterise sand ...

Effect of Polypropylene Fibre Reinforcement on the Consolidation, Swell and Shrinkage Behaviour of Lime-Blended Expansive Soil

Abstract: In this article, synthetic fibres in the presence of lime stabilisation are proposed as an alternative to overcome the issues related to shrink-swell distress in expansive soils. Two types of synth...

Prediction of vertical pile capacity of driven pile in cohesionless soil using artificial intelligence techniques

Abstract: Piles are used in substructures of different infrastructural constructions. Due to the complex nature of soil, there are different empirical models to predict the bearing capacity of piles. The objective of the present study is to develop prediction models for vertical loaded driven piles in cohesionless soil using a novel artificial intelligence (AI) technique multi-objective genetic programming (MOGP). Two other recent AI techniques, multivariate adaptive regression spline (MARS) and functional network (FN), are also used to compare the efficacy of different AI techniques. The results MOGP, MARS and FN models are compared in terms of different statistical parameters such as correlation coefficient (R), absolute average error, root-mean–square-error, overfitting ratio and P50. A ranking criteria approach has been implemented to assess the performance of the prediction models developed in this study along with other AI and empirical models available in the literature. The predictive model equation...

Laboratory study on undrained shear behaviour of overconsolidated sand–silt mixtures: effect of the fines content and stress state

Abstract: The post-liquefaction stability analysis of silty sand soil deposits that are prone to liquefaction becomes a major challenge in Geotechnical Earthquake Engineering. The objective of this laborator...

Study on pile ultimate capacity criteria and CPT-based direct methods

Abstract: Due to the variety of current Cone Penetration Test (CPT)-based methods of estimating the pile bearing capacity, for optimum design, it is necessary to evaluate the performance of such methods in various geotechnical conditions. Geotechnical databases including piling and in situ testing records have been recognised as useful tools for analysis, design and economical construction. In order to evaluate current CPT-based pile bearing capacity methods, AUT-CPT and Pile database has been compiled including 450 full scale pile load tests and CPT sounding records. This database consists of different pile types with a relatively wide range of geometries and various soil conditions. Forty-three records of piles driven in sand deposits were then employed to evaluate effects of ultimate capacity interpretation criteria from load displacement diagrams. The Brinch Hansen 80% criterion and the load at the displacement of 10% of the pile diameter were compared to estimated capacities from 10 CPT-based design methods cu...

Laboratory study of using biopolymer to reduce wind erosion

Abstract: This investigation is aiming to evaluate the effectiveness of biopolymer material in the suppression of wind erosion. Four different types of biopolymer (xanthan gum, guar gum, carrageenan and modified starches) were used in this study in three different concentrations (0.25, 0.50 and 0.75%). The effectiveness of the biopolymer on reducing soil erosion was measured from the mass loss of the specimens after being exposed to air device to simulate wind speeds similar to field conditions. Shear strength and liquid limits for treated specimens were measured and used to predict the loss of soil mass. Also, the effect of durability of biopolymer was studied through cycles of wet and dry. A neural network model was successfully used to predict the soil loss mass under different concentrations and cycles. The study verified the ability of biopolymer to reduce wind erosion; however, the erosion resistance varies according to the type of biopolymer used and its concentration. Although the effectiveness of biopolyme...

Quantification of desiccation cracks using image analysis technique

Abstract: This paper portrays a neoteric methodology for quantifying surface cracks and shrinkage that appears in the soil after desiccation under certain atmospheric conditions using image analysis technique. Soils over a wide range of plasticity are prepared by mixing high plastic sodium bentonite with non-plastic fly ash. Cylindrical specimens with different thickness, initial moisture content and densities were prepared and allowed to desiccate at an average temperature of 25 °C and relative humidity of 40%. The ImageJ software is used for image processing and Matlab for quantification of surface cracks and shrinkage in the specimens. The effect of different parameters like plasticity of soil, sample thickness, and initial moisture content on surface cracks and shrinkage are expressed in terms of crack density factor (CDF) and crack intensity factor (CIF). The result shows that both CDF and CIF increase with an increase in the plasticity index of the soil and initial moisture content of the specimens. In contra...

Effects of reinforcement on mechanical behaviour of cement treated sand using direct shear and triaxial tests

Abstract: The mechanical behaviour of artificially cement-treated Babolsar sand reinforced with sack, polyethylene terephthalate (PET) and polypropylene (PP) fibres is studied in this paper. Tests were conducted on cemented sand samples prepared at a relative density of 70%, with and without reinforcements on direct shear and triaxial apparatuses. Effects of parameters such as fibre content (FC), fibre type and normal or confining pressure (NP or CP) have been studied. Test results revealed that the addition of fibres had a significant effect on the behaviour of cemented sand. However, PP fibres are much more effective reinforcing materials than sack and PET fibres. A comparison between the results of direct shear tests and triaxial tests indicated that the fibre efficiency and its effect on soil behaviour is much more significant in triaxial tests compared with those in direct shear tests.

Monopile head stiffness for servicibility limit state calculations in assessing the natural frequency of offshore wind turbines

Abstract: Monopiles are used as foundations for offshore wind energy towers. These large diameter monopiles (4–6 m) which result in extremely stiff short monopiles do not follow the same elastic deformation patterns as those exhibited by small diameter (0.5–1.5 m) monopiles usually used for supporting structures in offshore oil and gas industry. Design recommendations (API and DNV among others) which have been developed on the basis of full-scale load tests on long, slender and flexible piles are not suitable for designing foundations for offshore wind turbine structures. Furthermore, as these facilities are very sensitive to rotations and dynamic changes in the soil-pile system, the precise prediction of monopile head displacement and rotation constitutes a design criterion of great importance. In this article, the semi-analytical finite element analysis which combines the conventional finite element method with Fourier series representation of displacements is used for the study of monopiles for offshore wind tur...

Experimental characterization of the undrained instability and steady state of silty sand soils under monotonic loading conditions

Abstract: This laboratory study aims to analyse the effects of gradation on the undrained instability using the undrained instability stress and steady-state ratios of silty sand soils. In this context, series of undrained compression triaxial tests were carried out on Fontainebleau (France) sand mixed with low plastic fines (I p = 5%) range F c = 0–30%. The samples were prepared at an initial relative density (D r = 52%) and subjected to three different confining pressures ( = 100, 200 and 300 kPa). The test results indicate that the gradation has a significant influence on instability stress and steady-state ratios of sand–silt mixtures. Moreover, the obtained data confirm the existence of simple correlations between undrained instability stress, steady-state ratios, fines content, void ratios and grading characteristics (D 10 , D 30 , D 50 , D 60 and C u ) of the materials under consideration. The introduced grading characteristics ratios (D 10R , D 50R and C UR ) and the equivalent state parameter a...

Clogging potential of tunnel boring machine (TBM): a review

Abstract: Tunnel boring machines excavating through soft soils face different challenges, one of which occurs when the soil sticks to the cutter face or the conveyor band and obstructs the machine. This phenomenon, commonly referred to as clogging, leads to wearing of the cutting wheel and transportation system, delays in the time schedule and economic loss. Although several laboratory devices can evaluate the adhesion mechanism of soil to metal, the method to measure adhesion has not been standardised. As clogging is also directly related to the construction phase, engineers are more concerned with methods to avoid this problem during construction. In this regard, the application of soil conditioners has become useful, the benefits of which include torque reduction, easier soil manageability and clogging reduction. However, the effectiveness of the soil conditioners is difficult to evaluate. To provide some insight into the topic, this paper describes the basic mechanism of clogging, the key parameters for its eva...

Assessment of sulphates effect on the classification of soil–lime–natural pozzolana mixtures based on the Unified Soil Classification System (USCS)

Abstract: According to the Unified Soil Classification System (USCS), fine-grained soils, such as clays and silts, can be classified by plotting the values of their plasticity index and liquid limit on a plasticity chart. However, soil classification can be affected by mineral additives and sulphates. The effect of both sodium (Na2SO4) and calcium (CaSO4·2H2O) sulphates on the soil classification of soil–natural pozzolana, soil–lime and soil–lime–natural pozzolana mixtures has been studied. The results showed that in the absence of sulphates, the addition of lime and lime‒natural pozzolana to both clayey soils improved considerably their soil classification. However, a negligible change in soil classification was recorded when natural pozzolana was used alone. The presence of sulphates influenced significantly the soil classification of these mixtures, especially with the curing period. The modification in the soil classification was more pronounced with the Na2SO4 than with the CaSO4·2H2O. Furthermore, the sensiti...

Swelling and compressibility characteristics of bentonite and kaolin clay subjected to inorganic acid contamination

Abstract: Increasing number of failures of industrial structures due to distress caused by acid contamination of foundation soils prompted the present study. This study examines the effect of highly concentrated inorganic acids on the swelling and compressibility characteristics of commercially available bentonite and kaolin clay. Two concentrations of sulphuric acid and phosphoric acid are used as pore fluids. Experimental results showed that bentonite specimens contaminated with both acids exhibited significantly lower swelling and compressions than uncontaminated bentonite. Decrease in double layer due to replacement of sodium cations by hydrogen ions is responsible for lower swelling and compressions. On the other hand, kaolin clay exhibited higher swelling with both acids than uncontaminated kaolin clay. However, compressibility marginally increased with both sulphuric acid and phosphoric acid. Formation of flocculant fabric along with mineral dissolution is responsible for deviations in compressibility behavi...

Soft soils improvement by granular piles reinforced with horizontal geogrid strips

Abstract: The present paper investigates the effect of geogrid, as horizontal strips, on the ultimate load intensity and bulging of floating as well as end bearing granular piles. The laboratory model tests ...

Effect of matric suction and initial static loading on dynamic behaviour of unsaturated cohesive soil

Abstract: Unsaturated soils are frequently encountered in various civil engineering projects; however, their dynamic behaviour is still unexplored. Present study evaluates the influence of matric suction, initial static loading, and load repetition on dynamic response of unsaturated cohesive soil (CH type). A series of cyclic triaxial tests have been performed on Ahmedabad-based cohesive soil under as-compacted conditions (unsaturated). Matric suction of soil is obtained using filter paper method at varying dry density and water content to characterise the behaviour of unsaturated soil. Application of initial static axial strain exhibited a unique stiffness response in loading and unloading phases of cyclic testing, and significantly impacted the cyclic strength response of unsaturated cohesive soil. The initial static axial strain in cyclic triaxial testing represents the conditions of a highway/railway embankment, where the embankment load on soil acts like initial static loading and passing vehicles like cyclic ...

Analysis of slope using modified pseudo-dynamic method

Abstract: Seismic design of slope is an important aspect in earthquake-prone areas to resist devastation due to earthquake load. This study presents the seismic stability analysis of homogeneous soil slope in which modified pseudo-dynamic method adopting limit equilibrium approach has been used. Results are presented in tabular form, which will serve as essential design parameters. Parametric studies show effects of soil properties and seismic forces on safety of slope. In addition, the required reinforcement strength against failure under seismic loading is evaluated and presented in figures that are useful to design reinforced slope.

Laboratory testing and numerical modelling on bearing capacity of geotextile-reinforced granular soils

Abstract: This paper summarises the details of an experimental work and numerical simulation on the bearing capacity of geotextile-reinforced granular soils with different fine grain contents (10 and 15%) which are mostly used in pavement design. The effects of position and number of geotextile layer(s) on the bearing capacity of reinforced specimens were investigated. The standard laboratory California Bearing Ratio (CBR) test was conducted to investigate the load-penetration behaviour of the unreinforced granular soils as well as reinforced ones with nonwoven geotextile layer(s). The reinforcements have been placed in samples in seven different scenarios (one, two and/or three layers of reinforcement in the bottom, middle and/or top compacted soil layers). The results indicated an increase in bearing capacity for most of the scenarios due to placing the geotextile layer(s); however, it was seen that increasing the number of reinforcement layers will not necessarily increase the reinforced soil mass bearing capaci...

Development of relationships between swelling and suction properties of expansive soils

Abstract: In this paper, an attempt is made to correlate swelling properties of expansive soils with their suction properties. To achieve this, both swelling, using a conventional oedometer apparatus, and su...

Compaction and swelling behavior of black cotton soil mixed with different non-cementitious materials

Abstract: A series of compaction tests and one-dimensional swell tests were conducted to study the effect of addition of various percentages of rice husk ash, fly ash, and stone dust on compaction and swelling behaviour of black cotton soil. Specimens were prepared by adding 4, 8, 12, 16 and 20% by weight of various industrial waste materials to the black cotton soil. Standard proctor test was adopted to study the compaction behaviour of mix. For swelling behaviour one-dimensional swell test was performed by fixed ring consolidometer. Test results have shown that the optimum moisture content (OMC) increases due to addition of rice husk ash while maximum dry density (MDD) decreases. However, slight decrease due to the addition of fly ash and no significant change due to the addition of stoned dust in MDD have been observed. Decrease in the OMC was observed due to the addition of fly ash and stone dust. Swell potential and swell pressure of the soil decrease with the increase in percentage of additives. It is found f...

Stresses in cast iron water mains subjected to non-uniform bedding and localised concentrated forces

Abstract: A number of water main breaks occur every year in municipalities due to ageing, aggressive environmental conditions and undesirable soil conditions. However, the failure mechanism observed in cast ...

Swelling behaviour of expansive clay beds reinforced with encased granular pile anchors

Abstract: Granular pile anchor (GPA) system is a simple and cost-effective foundation technique for resisting the uplift of foundation caused by swelling of expansive clay. This paper presents the heave resu...

Finite element modelling of undrained vertical bearing capacity of piles adjacent to different types of clayey slopes

Abstract: The bearing capacity of shallow foundations on slopes is commonly calculated from the existing design charts or using empirical equations. This paper presents the results of numerical studies carri...

Investigation on geomechanical behaviour and microstructure of cement-stabilized fly ash

Abstract: Present laboratory study investigated the geomechanical behaviour of cement-stabilised fly ash Class F fly ash collected from two different power plants in India was used in the study Fly ash was

Effect of reinforcement form on the behaviour of coir geotextile-reinforced sand through laboratory triaxial compression tests

Abstract: Use of natural products as reinforcement material offers various advantages such as availability, biodegradability, cost-effectiveness and environmental friendliness. Among the various natural products, coir is said to have the most desired engineering properties, i.e., tensile strength, stiffness and durability required for soil-reinforcement purposes. This paper studies the behaviour of sand reinforced with coir products in various form, as a reinforcement material through a series of triaxial compression tests. Improvement in strength and stiffness characteristics were obtained for sand reinforced with various coir products. The quantity of material used in terms of area is kept same in order to compare the reinforcement benefits of various forms of coir geotextile. The results show that coir geocell reinforcement provides superior performance compared to planar and discrete forms.

Lateral force–displacement prediction for buried pipe under different effective stress condition

Abstract: The aim of the present study is to elucidate the soil–pipe interaction in saturated sand with different effective stress. A force–displacement curve that took into account the variation of the effective stress was formulated based on the results of lateral loading experiments on a model pipe. To reproduce liquefaction experimentally, the effective stress of the soil bed was controlled by the upward seepage induced by a hydraulic gradient. The model pipe was pulled laterally under either displacement or load control. The experimental results indicate that the normalised force–displacement relationships can be well approximated by hyperbolic curves under each hydraulic gradient. When the variation in effective stress is reflected in the submerged unit weight of the soil, the two coefficients of the hyperbolic curves also show a hyperbolic dependence on the unit weight, and the ultimate resistive force increases in proportion to the unit weight. The predicted force–displacement curve fits relatively well to ...

Collapse behaviour of compacted red soil

Abstract: The phenomenon of collapse assumes significance in the geotechnical engineering applications such as earth dams and highway and railway embankments as the compacted soils in these applications are susceptible to wetting-induced failures. Therefore, the present study focuses to understand the influence of placement conditions and vertical stress on the wetting-induced collapse behaviour of compacted red soil through series of single oedometer collapse tests. The loading–collapse (LC) curves of compacted red soil for different dry unit weights were established over a large range of matric suctions in order to analyse the experimental results in the context of Barcelona basic model (BBM) elasto-plastic framework and also the experimental results were supported using the concept of LC curves defined in the BBM framework. The experimental results showed a path-dependent relationship of collapse potential with the water content at a given dry unit weight and vertical stress. The position of LC curves of the com...

Transport parameters of lead (Pb) Ions migrating through saturated lateritic soil–bentonite column

Abstract: This paper describes experiments and analyses conducted to determine the transport parameters of lead (Pb) ions diffusing through compacted lateritic soil–bentonite column. Experimental programme included the batch sorption tests and diffusion tests conducted in cells containing water-saturated lateritic soil treated with up to 10% bentonite by dry weight of soil. Specimens for diffusion tests were compacted at approximately 2% wet of optimum moisture content with British standard heavy (BSH) effort and exposed to municipal waste leachate placed on top of the specimens. Migration of Pb ions was monitored by measurement of pore water concentrations at various depths along the soil mixture columns together with the soil transport parameters (i.e. distribution coefficient, Kd, retardation factor, Rd and diffusion coefficient, D*). Based on sorption data, linear sorption isotherms were derived. Kd values of 2.0, 2.2, 2.5, 2.7, 3.9 as well as Rd values of 11.0, 11.1, 12.5, 12.5, 16.7 were recorded for 0, 2.5, ...

Effect of salt and NAPL on electrical resistivity of fine-grained soil-sand mixtures

Abstract: Electrical resistivity of soils are very important for various engineering projects, for example, subsurface transmission of either heated fluids or high-voltage buried power cables; storage and contamination of radioactive waste. Electrical resistivity mainly depends on the type of soil and its water content or saturation. The present study measures the electrical resistivity of commercially available kaolinite clay mixed with various percentages of sand & tried to establish a relationship between electrical resistivity and water content of the soil mixtures. Also, electrical resistivity has been measured with the addition of salts and non-aqueous phase liquid (NAPL) contamination into the kaolinite and/or kaolinite–sand mixture. The results show that electrical resistivity reduced drastically with the addition of salt but the resistivity increases with the addition of NAPL for kaolinite and kaolinite–sand mixtures.

Three-dimensional interaction diagram for the undrained capacity of inverted T-shape strip footings under general loading

Abstract: This paper presents new solutions of a three-dimensional (3D) interaction diagram for the undrained capacity of inverted T-shape strip footings under general loading. The two-dimensional plane strain finite-element analysis was employed to determine the stability of this problem. Parametric studies were performed to study the interactions of the combined vertical load (V), horizontal load (H) and bending moment (M) that were applied on top of the inverted T-shape footing. The combined action of vertical forces included both tensile (upward) and compressive (downward) loadings. The results of these analyses were summarised in terms of the dimensionless factors for V, H and M. Failure mechanisms associated with different locations on the 3D interaction diagram were compared and discussed. A closed-form approximate solution of the 3D interaction diagram for inverted T-shape strip footings under the V–H–M loading was proposed and compared with the finite-element solutions.

Influence of liquefaction on scour behind coastal dikes due to tsunami overflow

Abstract: In the present study, hydraulic model experiments were conducted to clarify the influence of liquefaction on the scour behind coastal dikes due to tsunami overflow. In particular, the variation of the scour profile (scour depth, scour length and scour area) due to liquefaction was discussed. Degree of liquefaction was controlled by upward seepage, which was induced by the head difference between a water tank and a sand bed. Six hydraulic gradients were applied to the sand bed. The experimental results showed that liquefaction had a significant impact on the scour profile. At high hydraulic gradient, slope failures occurred due to reduction of effective stress of the sand bed. As a result, scour length was increased by the slope failures. Furthermore, the maximum scour depth and scour area for high hydraulic gradient became smaller than that for low hydraulic gradient.