Elastic Modulus Of Soil Research Articles

Response analysis of subgrade soils using signal phase shift obtained from laboratory lightweight deflectometer (LWD) tests

Over the past decades, the use of fast and reliable measurement techniques of soil mechanical properties has gained popularity. The lightweight deflectometer (LWD) is among the tools developed that can allow one to determine the elastic modulus of soil. Viscosity response components in pavement or soil typically induce phase shifts between stress and strain peaks, which can be translated to phase angle. Subgrade soil may exhibit varying response types depending on its nature and characteristics. Using large laboratory subgrade samples, an experiment was designed to measure the elastic modulus and phase angle with an LWD in different stress and humidity conditions. A model associating the elastic modulus inferred from LWD tests with parameters describing stress, water content, and soil properties was proposed. This model is fundamentally inferred from the relationship between elastic modulus and phase shift, and was used to assess the relative contribution of varying conditions on soil stiffness.

Effect of Pile Driving on Ground Vibration in Clay Soil: Numerical and Experimental Study

In this study, peak particle velocity (PPV) values for driving three piles with diameters of 40 cm, 50 cm, and 70 cm in a clayey soil through the impact piling method are investigated by an experimental study and a numerical simulation. An experimental study is carried out on a scale of 1:20 of the operation. Numerical simulation is performed by using an axisymmetric model in PLAXIS 2D finite element software. Properties of the soil and the piles used in the experimental study are obtained from geotechnical tests and employed in the numerical simulation. The model has been verified by comparing the acquired PPV values with those measured in the experimental study. The results show a good agreement between the computed values and the experimental data. Moreover, measured peak particle velocities in the experimental study indicate that an increase in the diameter of the pile can increase the level of ground vibration. Some sensitivity analyses have been performed by numerical modeling to determine the effect of soil and pile properties on the changes of PPV. Also, increase in friction angle of the soil and pile diameter and reduction in elastic modulus of soil will increase the level of ground vibration. The results indicate that the amount of PPV at a distance of 100 cm is about 10.33% of the amount of PPV at a distance of 25 cm from the impact site to the pile with a diameter of 3.5 cm. In addition, this amount of reduction for pile with a diameter of 2.5 and 2 cm is equal to 8.31% and 12.77%, respectively.

Mindlin solution on ground deformation caused by the trench excavation during installation of concrete diaphragm wall panels

Concrete diaphragm walls (CDWs) are widely used as support of deep excavation in soft ground in urban areas. Ground deformation occurs during the excavation of trenches for the installation of the CDW panels due to ground stress release. This paper investigates the ground deformation during slurry trenching using Mindlin solution. The pressure of slurry used to protect the trench stability during excavation is simulated as a triangularly distributed load on the trench walls, the soil stress state is solved using Mindlin solution, and the horizontal and vertical ground displacement are obtained through integral transformation of ground strain. The rationality of the solution is verified through comparison between the analytical solution and field measurement. Sensitivity analyses are performed on soil elastic modulus, Poisson's ratio, trench excavation depth and panel length. Simplified formulation is proposed for the prediction of horizontal ground deformation. The impact of excavation stages and adjacent panels on the ground deformation is explored. The study finds that the Mindlin solution is able to provide an approximate solution on the ground deformation during slurry trenching, and the simplified formulation can be used to provide a fast estimate of the horizontal ground movement in engineering practice.

Pipe-soil vibration characteristics of natural gas pipelines during the pigging process

During the pigging process in long-distance natural gas transportation pipelines, the pig is easy to block and cannot be located accurately, resulting in serious economic losses. The analysis of pipe and soil vibration rule can be used as the basis for pig positioning. How to locate accurately the pig has become an urgent problem. In this study the coupled pipe-soil vibration model under the pigging action is proposed, and a three-dimensional symmetric pipe-soil vibration finite element model is established through ABAQUS. The influence of the pig running velocity and the friction coefficient of the inner surface on the vibration of the pipeline, as well as the influence of the propagation direction and the soil elastic modulus on the vibration propagation of the soil are studied. The research results show that the displacement amplitude of pipeline vibration increases with the increase of the running velocity of the pig, and at 0.8 m/s, the displacement reaches a peak of 27 μm. At the same time, the amplitude of pipe displacement increases as the friction coefficient between the pig and the pipeline increases. In the soil different directions, it is concluded that at 200 mm, the maximum displacement amplitude in the 45° direction can reach 15 μm. For the soil elastic modulus, when the propagation distance is 200 mm in soil with an elastic modulus of 10 MPa, the vibration velocity is significantly higher than that in other soils, and the maximum can reach 70 μm/s. Under the same conditions, the elastic modulus in the soil with an elastic modulus of 50 MPa, the maximum vibration velocity is 27 μm/s, indicating that the elastic modulus of the soil has a greater influence on the vibration velocity.

Predicting the seismic response of the short structures by considering the Whale Optimization Algorithm

This paper presents a newly improved version of the Whale Optimization Algorithm based on quantum theory by optimizing the Artificial Neural Network for the ground response approximation problems in short buildings. Based on the literature, Artificial Neural Network does not provide a proper response of ground surface prediction in seismic load applications. Hence, the main idea of this study is to assess the utilization of the whale optimization algorithm for calculating the columns’ horizontal deflection in the short structure under notable considered seismic loading. The input database utilized in this paper is the Chi-Chi earthquake that is occurred in 1999 in Taiwan. To provide the train and test databases for the artificial neural network algorithm and whale optimization algorithm, Finite Element models are used. The inputs contain the Chi-Chi earthquake’s dynamic time, soil elastic modulus, dilation angle, Poisson’s ratio, unit weight, friction angle, bending stiffness and axial stiffness. Also the columns’ horizontal deflection in their highest level is considered as the output. The results showed the higher reliability of the proposed WOA in calculating the ground response and the column’s horizontal deflection in short buildings subjected to the earthquake loading.

Cross-sectional thermo-mechanical responses of energy piles

Despite the widespread research on energy piles, there remain critical knowledge gaps in the cross-sectional thermal responses of concrete energy piles. This paper implements a unique research approach by developing and validating a numerical model with cross-sectional temperatures and strains measured in a field-scale energy pile (diameter = 0.6 m and length = 10 m), strengthening the reliability of modelling for energy piles. The numerical model was used to investigate the influences of inlet fluid temperature, soil thermal conductivity, soil elastic modulus, soil thermal expansion coefficient, and the presence of a nearby energy pile at a centre-to-centre distance of 3.5 m on the cross-sectional thermal responses of an energy pile. These investigations demonstrate the practical significance of the above parameters on the cross-sectional thermal responses of energy piles. The results show that the temperature and thermal stresses were largest at the centre of the pile and reduced with increasing radial distance to the pile's edge, with differences up to 4 °C and 2.2 MPa, respectively, between the centre and the edge. A comparison of the cross-sectional results with existing stress estimation methods in the cross-section of the piles, commonly based on average cross-sectional temperature and temperature measured at a single spot, reveals that existing methods lead to an overdesign of 2 MPa. Therefore, the actual temperature and stress variations in the planar cross-section of energy piles should be accounted for in the design of energy piles.

Nonlinear lateral displacement of the single pile – A seismic analytical investigation

In the construction industry, pile uses to enhance seismic stability of infrastructure and tower, if the soil faces insufficient bearing capacity and unallowable nonlinear lateral and vertical displacements. In this study, I assume that the nonlinear lateral displacement mechanism and its prediction were analyzed and developed based on the non-linear seismic load. (i) The nature of seismic load, (ii) length of pile, and (iii) soil elastic modulus become model parameters to assess the nonlinear lateral displacement and vibration mechanism of a single pile. In analytical processes, instead of using the whole seismic load for calculation nonlinear lateral displacement of the pile, a method was suggested for minimization of the analytical process. The statistical models and analysis have been applied for evaluating the accuracy of the analytical results and monitoring distribution probability of nonlinear lateral displacement of pile concerning different factors. The results illustrate the effect of the directions of seismic load, more specifically their combination, as it provides the non-linearity nature of seismic load, length of pile, and soil elastic modulus govern nonlinear lateral displacement mechanism and, these factors are important for predicting nonlinear displacement and monitoring mechanism vibration of the pile. The suggested method minimizes the analytical process, provides acceptable single pile seismic response prediction, and enhances the accuracy of the analytical results. The presented method can apply to solve many nonlinear dynamics problems, and it is not limited to single pile seismic analysis and design.

Numerical modeling of keying of vertically installed plate anchor in sand

Pile driven plate anchors are typically oriented vertically during installation. To function properly in a mooring system they must be rotated, or keyed, to an angle normal to the mooring line load. Keying involves reduction in anchor embedment, with concomitant reduced load capacity, so realistic prediction of embedment loss during keying is essential to design. This study investigates the kinematic behavior and load capacity of a vertically installed strip plate anchor embedded in uniform cohesionless soil using large deformation finite element (LDFE) analysis. Embedment loss during keying is evaluated as a function of load eccentricity, load angle, and plate thickness. The model indicates that the plate angle at which maximum pullout resistance occurs increases with increasing eccentricity. The finite element simulations also show the embedment loss during keying decreases with increasing load eccentricity. Loss of anchor embedment increases with increasing pullout angle. The model also predicts that the loss in anchor embedment increases with decreasing anchor thickness, especially when eccentricity is small. The simulations show anchor during keying was essentially independent of the soil elastic modulus to have virtually no effect on keying behavior for shallow anchors, but elastic effects can be significant for deeply embedded anchors.

An Investigation on the Settlement of Shallow Foundations Resting on Cross-Anisotropic Soil Deposits

Natural soil deposition process results in formation of anisotropic planes with different properties along different directions, and hence, such natural deposits possess inherent anisotropy. On the other hand, an estimate of the elastic settlement of surface foundations placed on such anisotropic deposits is very important. In this research, the effect of anisotropy (in fact, cross-anisotropy) on the elastic settlement of shallow foundations resting on anisotropic granular soils, often sands, has been investigated. The most important properties in this work, in addition to the geometry of the footing, are the soil modulus of elasticity, Poisson’s ratio and the ratio of these moduli along anisotropic planes in a cross-anisotropic medium. The governing equations of deformation in such media are first presented. Then, the elastic settlement of shallow foundations resting on such media has been estimated using the finite difference method, and then, some influence factors are presented. The factors are useful in estimating the elastic settlement of shallow foundations on cross-anisotropic soils, when the soil properties along two perpendicular directions are known. A series of design charts are provided in non-dimensional form so as to avail their practical use in a general form.

The effect of stem and root-plate defects on the tree response during static loading—Numerical analysis

Despite continual development of the tree pulling test, there is no systematic study on the interaction of stem and root-plate stiffness in relation to tree assessment results. New methods involving numerical modelling and optical techniques provide tools for effective and deeper understanding of the interaction of stem and root-plate stiffness. Within this study, a finite element (FE) model of the tree response to static loading was developed, and the interaction between the stem and root-plate stiffness was analysed on three levels: longitudinal stem strains, root-plate inclinations and stem deflection curve. The model was validated at all three levels by comparison with experiment. Sensitivity analysis of the validated model showed a significant correlation of root-plate stiffness represented by the root volume and soil elastic modulus to the tree response. By analysing the defects in tree response, the importance of proper location for detection of strains and inclinations was demonstrated, especially regarding asymmetrical defects. A numerical estimate of the second derivative of displacement based on the Taylor approximation, was used to analyse the stem deflection curve.

Interactional Effect of the Influential Parameters on Seismic Behaviour of the Concrete Surface Tanks

Given to the importance of the tanks and their various applications in different industries, studying the seismic behaviour of these facilities is essential. In such structures, obtaining exact theoretical solution for the seismic behaviour of the tanks is very difficult due to the existence of the soil-structure interaction. In this study, seismic behaviour studying has been taken into account and in addition to considering three-dimensional model of finite element model of a surface rectangular tank and its beneath soil given to SSI and FSI effect, we have done required analysis and Drucker–Prager nonlinear model has been used to investigating more exactly to describe soil behaviour. Euler–Lagrange view with optional mesh displacement has been used for modelling tank-water interaction. According to the obtained results from this modelling, soil beneath the tank and soil-structure interaction affect highly on seismic behaviour of the surface tanks. Meanwhile, the response of the structure to the density changes and soil modulus of elasticity is more sensitive and changes in the coefficient of friction coefficient between the foundation surface and the soil and the internal friction angle do not have tangible effect on the response. The results reveal that the liquid containers response is more sensitive to the changes of the density and the soil modulus of elasticity more than friction coefficient between the surfaces and foundation and internal angle friction.

Reliability analysis of laterally loaded piles in marine environments considering the degradation of flexural rigidity

In this paper, the governing equation of chloride diffusion in reinforced concrete square piles is presented. The deterioration process of a pile caused by chloride-induced reinforcement corrosion is analyzed. The time-varying degradation coefficient of the flexural rigidity of piles induced by reinforcement corrosion is obtained. The time-varying failure probability and reliability index under the displacement failure criterion are calculated by using the Monte Carlo simulation method. The sensitivity of the coefficient of variation (COV) and mean value of the significant parameters for the time-varying probability density function (PDF) curves is analyzed. The results indicate that the degradation coefficient of the flexural rigidity and the reliability index decrease with increasing service time, while the failure probability increases with increasing service time. The peak value of the PDF curve of the pile head displacement decreases as the COV of the lateral load, soil elastic modulus and mean value of the lateral load and bending moment increase. The displacement of the pile head corresponding to the peak value increases substantially with increasing lateral load and bending moment, and decreases significantly with increasing soil elastic modulus and concrete elastic modulus.

Settlement Response of a Multi-Story Building

The settlement calculation of a multi-story building is a challenging task due to the variation of soil properties and the use of an appropriate constitutive model for the reliable representation of soils’ stress-strain behaviors. In this study, the settlement response of a multi-story building was calculated with the simple Mohr-Coulomb Model (MCM) and the Hardening Soil Model (HSM). The effect of soil modulus of elasticity using both models was investigated on the overall settlement response of the building. Results indicated that MCM overestimated immediate settlement in a range of 50 to 65% compared to HSM. The settlement response of the building calculated with both models was within the allowable range. The results of this study can be helpful for geotechnical engineers working on reliable predictions of the settlement of multi-story buildings.

Modeling of energy transfer and parameter effects on it of a vibrator-ground system

The amount of energy transferred to the ground truly represents the performance of the seismic vibrator. So, it is crucial to investigate the transfer of energy in the vibrator-ground system and how parameters affect it. For this purpose, a model of vibrator-ground system considering frequency change is developed based on half-space theory, and methods of calculating energy transfer is innovatively proposed. Results show that the total energy done by the hydraulic force on the vibrator-ground system in the frequency band of 3–200 Hz is 3.156×105 J, and 9.11% of the energy is transferred to the ground. In addition, effects of structural parameters and soil parameters on energy transfer are carried out. It is concluded that lightweight reaction mass can significantly increase the total energy, but heavier reaction mass generates more ground energy. Baseplate with small mass not only helps the vibrator to transmit energy uniformly but also generates more ground energy above 100 Hz. Larger baseplate area can improve the baseplate-ground interaction to transfer more energy to the ground. For the effects of soil on energy transfer, the ground energy in low-frequency band is mainly dominated by soil elastic modulus, and both elastic modulus and density of soil have great effects on energy transferred to ground at high frequencies.

Propagation of settlement in soft soils induced by tunneling

In practice, it is vital to know the propagation law of settlement in soil induced by tunneling. In this paper, a novel two-dimensional subsurface settlement propagation model is established based on the stochastic medium theory. The governing equation is solved with the assumed settlement profile at the tunnel crown using the Fourier transform method. Subsequently, the sensitivity of the subsurface settlement to the model parameters B and N is discussed. A database containing 12 case histories is used to establish the relationship between the elastic modulus of soil and the model parameters B and N by the linear fitting method. Results show that the model parameters B and N can reflect the vertical propagation ability and the compression (or swelling) performance of the overlying soil, respectively. Finally, the applicability of the proposed model is demonstrated with a case study of tunneling in clays. It is concluded that the model presented in this paper is highly effective and convenient for use in practice.

Effect of Additive Chemicals on Soil Characteristics

The occurrence of landslides in the hills of Walahir, Kidang Pananjung village, Cililin subdistrict. Bandung in May 2004 needed attention and research so that the causes of the landslide could be identified. This landslide took many lives and property, heaped around 5 hectares of rice fields and residents’ villages below and claimed 15 lives. Based on geotechnical investigations, the slip plane is at a depth of 4 meters from the ground surface and the area of the landslide ranges from 30,000 m2 leaving weathered rock beneath. Is the opening of agricultural land and fields followed by the use of chemical fertilizers is one of the causes of landslides? This study aims to determine the effect of a single chemical fertilizer (Urea, Za, SP36) and compound (Green Giant NPK, MKP) on the soil under conditions of optimum water content and water saturation or soaked which are carried out at the Chemical Laboratory of the Department of Energy and Mineral Resources of Bandung and Mechanics Laboratory Bandung Institute of Technology. Research on the influence of chemical fertilizers which is carried out using percentages of 1%, 2% and 3% with a relatively short ripening time intends to analyze the extent to which chemical fertilizers have an effect. Research is limited to the identification of minerals and chemical elements of original soil, soil physis properties, Atterberg boundaries, soil index properties, soil classification, soil elastic modulus. Hypothesis; The chemical content of fertilizers in the soil causes changes in soil characteristics. The method of taking original soil is by drilling original soil around the area where landslide disaster occurred at the same height as the height of the landslide slope, soil samples taken from depths of 1 meter and 3 meters from the surface of the land or the base layer between soil and rocks based on ASTM D-1452, 1587, 1586. Laboratory data from the original soil and chemical soil mixture of fertilizers is needed as input data for the study material and is an analytical proof of the hypothesis. Based on research that the presence of chemical fertilizers in soil samples with optimum water content causes the water content in the soil to decrease this is because chemical fertilizers absorb water while the soaked soil samples cause the water content in the soil to increase, the plasticity index decreases so that changing the soil classification in the area from OH-MH becomes ML-OL unified classification and the elasticity of the soil changes. Based on the analysis that the presence of chemical fertilizers showed an influence on the physical properties of the soil where soil minerals are very possible the replacement of cations of the chemical elements contained in the chemical fertilizers. The addition of chemical fertilizer by 3% and curing time for 14 days is a maximum condition compared to the percentage and age of other curing.

Stress–strain characteristics of landfill clay cover barriers under geogrid reinforcements

Low shear strengths in landfill clay cover barriers lead to the development of tensile cracks in the soil, thus decreasing the usefulness of the barrier to resist water inlet into the landfill system. As cracks begin to form, water infiltration increases, thus increasing the wastewater interaction, leading to the development of the excess amount of leachate. Usage of geogrids within the landfill clay cover barrier has found wide-scale applications in bolstering the shear strength of the soil and thus preserving its utility. In this paper, the shear behavior of landfill clay cover soil with geogrids has been analyzed using triaxial compression tests. Significant parameters such as geogrid properties, initial geogrid spacing, number of geogrids, confining pressure and spacing between the geogrids have been investigated. A soil mixture of kaolin clay and sand, in 4:1 ratio, respectively, representing the typical characteristics of landfill clay cover barrier soil found in the field, was compacted at OMC + 5% and was used in the present study. The study demonstrates the increase in shear strength of landfill clay cover barrier with geogrids and its interdependence on geogrid spacing and geogrid properties, number of reinforcement layers and confining pressure. The inclusion of geogrids improved the load-carrying capacity and the axial strain at failure of the soil, thus signifying the benefits of inclusion of geogrids in cover barriers, especially to prevent tensile cracks. The results obtained from the triaxial tests were used for the computation of elasticity modulus of the cover barrier soil. Significant parameters necessary for the computation of the elasticity modulus were chosen, and the model with a confidence level greater than 95% was presented to deduce the settlement in geogrid-reinforced landfill clay cover barriers.

Scale effect study on the modulus of subgrade reaction of geogrid-reinforced soil

Both experimental and numerical investigations conducted on strip footing laying down over the geogrid reinforced fine sand bed. Firstly, an evaluation of the significance of geogrid reinforcement to enhance the soil’s strength is required to carry out a series of a small-scale model of reinforced and unreinforced soil beneath static loading. Next, the series of the large-scale numerical analyses were implemented to define the soil bed reaction modulus and bearing capacity ratio of reinforced sand soil in plane strain conditions. The Mohr–Coulomb soil constitutive model was used to represent the fine sandy soil and the linear elastic tension model was utilized for modeled geogrid reinforcement elements. One of the most beneficial outcomes in the unreinforced soil case, the ultimate bearing capacity progress occurs by developing the width of the strip footing. Then in reinforcing case, an uppermost geogrid layer’s depth under the footing and the fittest spacing between the reinforcing layers are not affected by the wide ranges of the footing widths. Their optimum values are similar to the works of literature (u/B = 0.3 and h/B = 0.4), but they are affected by soil friction angles. Finally, the achievement of this study indicates that the coefficient of soil reaction is associated with a nonlinear behavior with the relative ratio of tensile stiffness of the geogrid to the elasticity modulus of soil and enhanced by increased the number of geogrid layers. The influence of geogrid length on subgrade modulus is negligible and only the effective depth is affected it. The value of reaction modulus decreases when both the footing width and settlement increase. A simple new method is proposed to determine an approximate value of subgrade reaction modulus in reinforced soils.

Effects of backfill soil on pipeline’s mechanical response subjected to perilous rock impact

Perilous rock impact is one of the most serious geological disasters that threats to buried pipeline security. Mechanical behavior of buried pipeline in rock stratum impacted by perilous rock was simulated in this paper. And effects of impact velocity and backfill soil parameters on stress and strain of pipeline were discussed. The resluts show that cross section shape of pipeline is oval when impact velocity is small. Impact dent appears on pipeline with the increasing of impact velocity, buckling is more serious and plastic stain increases. Under low velocity impact, stress and plastic strain decrease with the increasing of soil's elastic modulus. Plastic strain increases first and then decreases with the increasing of soil's Poisson's ratio. With the increasing of soil's cohesion, plastic strain increases, but stress first increases and then decreases. Under high velocity impact, deformation and plastic strain increase with the decreasing of elastic modulus and Poisson's ratio. But cohesion has a small effect on buckling behavior of pipeline.

Soft computing approach for prediction of surface settlement induced by earth pressure balance shield tunneling

Estimating surface settlement induced by excavation construction is an indispensable task in tunneling, particularly for earth pressure balance (EPB) shield machines. In this study, predictive models for assessing surface settlement caused by EPB tunneling were established based on extreme gradient boosting (XGBoost), artificial neural network, support vector machine, and multivariate adaptive regression spline. Datasets from three tunnel construction projects in Singapore were used, with main input parameters of cover depth, advance rate, earth pressure, mean standard penetration test (SPT) value above crown level, mean tunnel SPT value, mean moisture content, mean soil elastic modulus, and grout pressure. The performances of these soft computing models were evaluated by comparing predicted deformation with measured values. Results demonstrate the acceptable accuracy of the model in predicting ground settlement, while XGBoost demonstrates a slightly higher accuracy. In addition, the ensemble method of XGBoost is more computationally efficient and can be used as a reliable alternative in solving multivariate nonlinear geo-engineering problems.