Liquefaction Behavior Research Articles

Coupled influence of content, gradation and shape characteristics of silts on static liquefaction of loose silty sands

Static liquefaction is a challenging problem of geotechnical engineering as its consequences are generally catastrophic when they occur on site. Previous laboratory studies focused on various factors that could influence the static liquefaction potential of silty sands. Most popular of those investigated factors are stress conditions, deposition method and fines content. The purpose of the present study is to investigate the other possible factors, of which very little is known, mainly focusing on the silt characteristics including grain size distribution, relative size, and shape effects of the silt grain matrix within the sand. Undrained monotonic triaxial compression tests were conducted on thirty sands with varying fines contents, which were prepared by mixing three base sands (Sile Sands 20/30, 50/55, 80/100) with same geologic origin but with different gradations and three different non-plastic silts (IZ, SI and TT silts) with different gradations and shape characteristics. The experimental results revealed that each of the mentioned factors had their own influence on static liquefaction behavior of sands. The static liquefaction potential of all the three sands in this study was observed to increase with decreasing coefficient of uniformities of the silt grain matrix (CUsilt) in sands. For a particular base sand, static liquefaction potential was observed to increase with decreasing mean grain diameter ratio (D50-sand/d50-silt) due to change of silt gradation. However, shape characteristics of the silt grains are also found to be another important factor, in certain cases observed to have a greater influence than mean grain diameter ratio criterion. As an example, it was shown that at the same FC, base sand, depositional energy and consolidation stress, angular nature of TT silt potentially caused more meta-stable contacts (weaker grain contacts that promote excess pore pressure generation during shearing) within the specimens than sub-rounded SI silt, which caused specimens with TT silt to be more liquefiable than their counterparts with SI silt. Moreover, it was found that there is a coupled relationship between the fines content and investigated silt characteristics (gradation, mean size, shape effects) on the static liquefaction behavior of sands. The unexpected trend regarding the last finding is that the mentioned influence of silt characteristics (i.e. gradation, size and shape) on static liquefaction of sands becomes more considerable with decreasing fines content at loose states.

Microscopic Mechanism Analysis on Liquefaction of Dredged Silty Sand in Land Reclamation Based on Discrete Element Method

Cyclic consolidation-undrained triaxial tests were performed to investigate the liquefaction behavior of dredged silty sand in land reclamation. The liquefaction behavior of dredged silty sand in the triaxial tests was simulated using discrete element method. Constant volumetric method and initial liquefaction standard were introduced in the simulations. The micro-parameters of dredged silty sand were inversed. The liquefaction micro-mechanism of dredged silty sand was analyzed based on the numerical simulations. The pore water pressure of samples reached effective consolidation pressure and average coordination number decreased quickly when the initial liquefaction was reached.

Evaluation of Liquefaction Potential in Sand–Tire Crumb Mixtures Using the Energy Approach

This research explores performance of the energy approach for evaluating the liquefaction potential of sand–tire crumb mixtures. Thirty-six stress-controlled undrained cyclic torsional tests were performed under three different confining pressures on samples with different rubber contents. The effect of such parameters as the rubber content and confining pressure on liquefaction behavior of sand–rubber mixtures was studied using the energy approach. Test results indicated that, unlike the observations made on the pure sand sample, in the case of sand–rubber mixture with 25% rubber content, when the initial liquefaction is triggered, the dissipated shear energy increases with continued cyclic loading. The increasing trend is stopped when the pore water pressure reached the initial consolidation stress (Ru = 1). This observation indicates that for the case of sand–tire crumb mixture, the dissipated energy per volume is associated only with the progression of pore water pressure. Moreover, the results show that the required energy for liquefaction occurrence decreases with the increase in the rubber content. The minimum amount of required energy is determined for mixtures with 10% rubber content. As the result, the inclusion of crumb rubber decreases the liquefaction resistance of sand. However, when the rubber content increases from 10 to 25%, the resistance to liquefaction improves. The generation rate for mixture with 25% rubber content is somewhat faster than that of the clean sand and the mixture with 10% tire crumbs, as it is expected.

Effect of initial relative density on the post-liquefaction behaviour of sand

Understanding the behaviour of soils under cyclic/dynamic loading has been one of the challenging topics in geotechnical engineering. The response of liquefiable soils has been well studied however, the post liquefaction behaviour of sands needs better understanding. In this paper, the post liquefaction behaviour of sands is investigated through several series of multi-stage soil element tests using a cyclic triaxial apparatus. Four types of sand were used where the sands were first liquefied and then monotonically sheared to obtain stress-strain curves. Results of the tests indicate that the stress-strain behaviour of sand in post liquefaction phase can be modelled as a bi-linear curve using three parameters: the initial shear modulus (G1), critical state shear modulus (G2), and post-dilation shear strain (γpost−dilation) which is the shear strain at the onset of dilation. It was found that the three parameters are dependent on the initial relative density of sands. Furthermore, it was observed that with the increase in the relative density both G1 and G2 increase and γpost−dilation decreases. The practical application of the results is to generate p-y curves for liquefied soil.

Liquefaction characteristics of gravelly soil under cyclic loading with constant strain amplitude by experimental and numerical investigations

In order to investigate the liquefaction behavior and meso-mechanism of gravelly soil under cyclic loading with constant strain amplitude, the undrained dynamic triaxial test, CT scan test and numerical simulations by discrete element method (DEM) are performed. Effects of gravel content and the evolution of liquefaction nmeso-mechanism are analyzed respectively. Test Results show that the liquefaction resistance of gravelly soil increases considerably with the increasing gravel content due to growing in number of gravel-to-gravel contact. DEM simulations reflect the macro mechanical property of saturated gravelly soil in the cyclic triaxial test, and show anisotropy is the most important mechanical properties of gravelly soil liquefaction under cyclic loading with constant strain amplitude. In process of the liquefaction, the backbone force-chain is gradually destroyed, and magnitude of normal contact force decreases to zero until initial liquefaction. Both of the fabric and force-chain evolution demonstrate a consistent deflection of the principal stress axis.

3D Methods for Examining Soil–Building Interaction for Nonlinear Soil Behavior Based on an Input Wave Field

AbstractThis paper proposes three-dimensional (3D) simplified nonlinear methods for examining the soil–building interaction for nonlinear behavior of soils based on an input seismic wave field. A seismic wave field is defined as seismic waves propagating in a 3D medium. The proposed 3D methods were developed on the basis of the 3D linear method, which was recently proposed to adequately treat seismic surface waves trapped by a several-kilometer-deep underground structure. To demonstrate the feasibility of the proposed methods, interaction analyses of a midrise RC building and a wood building were performed in the reclaimed zone of Tokyo Bay in the cases of soils with linear, nonlinear, and liquefaction behavior for the 1923 Kanto earthquake. These interaction analyses provide a reasonable evaluation of building performance. In particular, building responses became excessively large, following extremely large increases in the amplitudes of surface waves in liquefied soils. The building responses provide si...

Investigation of the Relationship Between Reed Liquefaction Behavior and Thermodynamic Properties of Epoxy Resin Based on Liquefied Reed

Although epoxy resin was developed from liquefied sustainable resources, such as wood, corn bran, bagasse, etc., the use of liquefied biomass for manufacturing high performance epoxy resin has been limited because of the effects of these materials on properties of epoxy resin were unclear. Thus, the liquefied reed-based epoxy resin was synthesized by glycidyl etherification between liquefied reed and epichlorohydrin in this study. The relationship between reed liquefaction behavior and thermodynamic properties of liquefied reed-based epoxy resin was investigated by Gel permeation chromatography (GPC) and Thermogravimetric analysis (TGA), as well as by determination of residue content, phenol content, epoxy index and mechanical performance. The results indicated that not only high content of bound phenol, but also broad molecular weight distribution of liquefied reed would widen molecular weight distribution of synthetic epoxy resin, which was a major cause of low adhesive shear strength and great thermal stability of cured resin.

Effect of saturation on liquefaction resistance of iron ore fines and two sandy soils

Over the past several years, the International Maritime Organization (IMO) has become increasingly concerned about the liquefaction of unsaturated solid bulk cargo (e.g. iron ore fines) during maritime transportation. This concern has arisen due to several accidents including the capsizing of vessels. In addition, although the resistance against liquefaction of ordinary unsaturated soils is higher than for saturated soils, possible key parameters governing the liquefaction resistance of unsaturated soils (RL,unsat) have not yet been clearly identified. Therefore, in this study, undrained cyclic loading tests of saturated and unsaturated iron ore fines and two sandy soils were conducted using a triaxial apparatus to reveal the liquefaction behavior of iron ore fines and to find the key parameters governing RL,unsat. Through comparisons, it was found that the liquefaction behavior of iron ore fines is similar to that of sandy soils. The degree of saturation and potential volumetric strain, which have been proposed as the governing parameters of RL,unsat, were examined based on experimental data obtained in this study and by other researchers. It was shown that neither of the two parameters correlate with the liquefaction resistance ratio (LRR), a ratio of RL,unsat to the liquefaction resistance of the saturated soils (RL,sat) with a unique relationship, especially when considering soils with considerable fines content. Following the concept of potential volumetric strain, which considers the compressibility of pore air in the unsaturated soils, volumetric expansion due to the reduction in confining pressure during cyclic loading is further considered, and a new index, the volumetric strain ratio (Rv) is proposed in this study. According to the experimental data obtained in this study, Rv exhibits a much better correlation with LRR than the two former parameters.

Liquefaction of Torrefied Wood using Microwave Irradiation

Torrefaction is an effective pretreatment method to improve the uniformity and quality of lignocellolosic biomass before further thermal processing (e.g., gasification, combustion). The objective of this study was to determine the impacts of torrefaction as a pretreatment before liquefaction. Wood chips were torrefied for 2 h at three different temperatures (230, 260, 290 °C) and then subjected to microwave-assisted liquefaction, as was the untreated wood control. The dielectric properties of liquefaction materials, including the biomass samples and liquefaction reagent, were measured to evaluate their abilities to convert electromagnetic energy to heat. The effects of liquefaction time, temperature, and catalyst concentration on the liquefaction efficiency were also investigated. It showed that torrefaction temperature had significant influence on the liquefaction behavior of wood materials. Wood treated at the lowest torrefaction temperature (230 °C) retained the most structural/compositional characteristics of untreated wood and therefore they both exhibited similar liquefaction behaviors. The higher treatment temperature (290 °C) led to higher liquefaction residue contents, attributed to the increase in carbon content and hydrophobicity from torrefaction.

Plasticity modeling of liquefaction effects under sloping ground and irregular cyclic loading conditions

The formulation of the constitutive model PM4Sand [7] is modified to improve simulations of liquefaction-induced deformations of sloping ground subjected to uniform and irregular cyclic loading. Existing laboratory test data on the response of liquefiable sand under sloping ground conditions subjected to uniform cyclic loading are reviewed and additional experimental data from undrained cyclic direct simple shear (DSS) tests of liquefiable sand under sloping ground conditions subjected to irregular cyclic loading are presented. The previous version of the PM4Sand model (Version 2) and its limitations in modeling liquefaction effects in sloping ground with uniform and irregular cyclic loading are described. Evidence from the laboratory tests show that it is the effect of loading history on the dilation and stiffness characteristics of the response that is not properly captured by Version 2 of the model. The modifications made in Version 3 include a revised dependency of dilation and plastic modulus on the fabric tensor and its history. These modifications are introduced using irregular cyclic DSS test results to illustrate the motivations for the changes in the constitutive equations. Finally, two examples of calibration are presented: one against a specific laboratory test result for a single sand and one against an engineering correlation describing trends observed for many sands across a broader range of relative densities, confining stresses, and loading conditions. The updated formulation in Version 3 of the model is shown to better approximate liquefaction behaviors for sloping ground and irregular cyclic loading conditions.

Kinetic and product composition study on the cellulose liquefaction in polyhydric alcohols

The liquefaction process of cellulose in polyhydric alcohols (PEG 400 and glycerol) was studied by TG-FTIR. Three stages were observed during the solvolysis process and the main liquefaction stage could be further divided into two zones. The differences of liquefaction behavior of cellulose in the two solvents were compared, and the functional groups of volatiles produced by solvolysis were also evaluated. A step-wise procedure based on iso-conversional and Master-plots methods was used for the kinetic and mechanism analysis of the main liquefaction stage. The calculation results based on the kinetic model were in agreement with the experimental data of the conversion rate. The kinetic parameters and mechanism functions between cellulose liquefaction in PEG400 and in glycerol were quite different, which verified that solvolysis behavior and reaction process were seriously influenced by solvent species. Finally, the detailed types of volatiles and product distribution were measured by Py–GC–MS.

EFFECT OF FINES ON LIQUEFACTION USING SHAKE TABLE TEST

Earthquake is one of the most disastrous natural calamities resulting into considerable damages. One of the most detrimental effects caused due to earthquake is liquefaction. This paper deals with experimental investigation of effects of fines content on liquefaction behavior using shake table test. A test program consisted of total 19 tests conducted on saturated cohesionless sand with varying amount of non-plastic silt. The behavior of such silty sand in the relative density range 30 to 60% has been studied by subjecting the specimens to a specific acceleration of 0.54g. Effect of silt content and the relative density on generation of pore pressure and thereby initiation of liquefaction has been studied. The results obtained from the present study showed that cyclic stress ratio (CSR) values decrease with the increase in fines content for lower relative densities. Delay in development of pore pressure is observed with the increasing fines content. This indicates that higher silt contents at higher densities offer better resistance to liquefaction. Further, for lower densities and lesser silt contents liquefaction occurred at pore pressure ratio even less than one. The trend observed for CSR and relative density is similar when compared with triaxial test reported in literature. The points where liquefaction has occurred in the field, when checked in the present study, they lie in ‘YES’ zone of liquefaction.

Co-seismic and post-seismic behavior of an existed shallow foundation and super structure system on a natural sand/silt layered ground

Purpose – The purpose of this paper is to evaluate the co-seismic and post-seismic behaviors of an existed soil-foundation system in an actual alternately layered sand/silt ground including pore water pressure, acceleration response, and displacement et al. during and after earthquake. Design/methodology/approach – The evaluation is performed by finite element method and the simulation is performed using an effective stress-based 2D/3D soil-water coupling program DBLEAVES. The calculation is carried out through static-dynamic-static three steps. The soil behavior is described by a new rotational kinematic hardening elasto-plastic cyclic mobility constitutive model, while the footing and foundation are modeled as elastic rigid elements. Findings – The shallow (short-pile type) foundation has a better capacity of resisting ground liquefaction but large differential settlement occurred. Moreover, most part of the differential settlement occurred during earthquake motion. Attention should be paid not only to the liquefaction behavior of the ground during the earthquake motion, but also the long-term settlement after earthquake should be given serious consideration. Originality/value – The co-seismic and post-seismic behavior of a complex ground which contains sand and silt layers, especially long-term settlement over a period of several weeks or even years after the earthquake, has been clarified sufficiently. In some critical condition, even if the seismic resistance is satisfied with the design code for building, detailed calculation may reveal the risk of under estimation of differential settlement that may give rise to serious problems.

Influence of solvent type on microwave-assisted liquefaction of bamboo

Microwave-assisted liquefaction of bamboo in glycerol, polyethylene glycerol (PEG), methanol, ethanol, and water were comparatively investigated by evaluating the temperature-dependence for conversion and liquefied residue characteristics. The conversion for the liquefaction in methanol, ethanol, and water increased with an increase in reaction temperature, while that for liquefaction in glycerol and PEG was converse. The results of Fourier transform-infrared spectra for the liquefied residues revealed that cellulose was the main resistance to bamboo liquefaction in methanol, ethanol, and water. Glycerol could be selected as a commendable liquefacient for the solvolysis of bamboo components at low temperature using microwave energy. Moreover, liquefaction behaviors in glycerol and methanol under different temperatures were also distinguished by scanning electron microscopy images.

Cyclic resistance and liquefaction behavior of silt and sandy silt soils

The liquefaction behavior and cyclic resistance ratio (CRR) of reconstituted samples of non-plastic silt and sandy silts with 50% and 75% silt content are examined using constant-volume cyclic and monotonic ring shear tests along with bender element shear wave velocity (Vs) measurements. Liquefaction occurred at excess pore water pressure ratios (ru) between 0.6 and 0.7 associated with cumulative cyclic shear strains (γ) of 4% to 7%, after which cyclic liquefaction ensued with very large shear strains and excess pore water pressure ratio (ru>0.8). The cyclic ring shear tests demonstrate that cyclic resistance ratio of silt and sandy silts decreases with increasing void ratio, or with decreasing silt content at a certain void ratio. The results also show good agreement with those from cyclic direct simple shear tests on silts and sandy silts. A unique correlation is developed for estimating CRR of silts and sandy silts (with more than 50% silt content) from stress-normalized shear wave velocity measurements (Vs1) with negligible effect of silt content. The results indicate that the existing CRR–Vs1 correlations would underestimate the liquefaction resistance of silts and sandy silt soils.

Effects of Fibre Reinforcement on Liquefaction Behaviour of Poorly Graded Sands

The objective of this study is to evaluate the liquefaction behaviour of fibre reinforced sand concerning the lower and upper limits of medium relative densities of 50% and 70%, respectively. A systematic testing program of the stress-controlled cyclic triaxial tests was performed on saturated sand samples with and without fibre reinforcements under undrained conditions. The confining pressure for all test cases was 100kPa reflecting the actual overburden pressure in field conditions. The effect of parameters such as fibre content (0.25%, 0.50%, and 1%) and fibre length (6 mm and 12 mm) on the liquefaction behaviour of unreinforced and reinforced specimens was studied. Upon increasing the fibre content and fibre length, the number of loading cycles leading to liquefaction increased. Pore water pressure and shear strain curves are obtained for the fibre reinforced medium dense sands. Furthermore, the boundaries presented in the literature on the sands are shown in comparison with the results of fibre reinforced sands of this study. As a conclusion, the outcomes of this study are useful to develop insight into the behaviour of clean and fibre-reinforced medium dense sands under seismic loading conditions. Based on the test results, it was found that the number of loading cycles has significant influence on the generation of excess pore pressure.

Influence of saturation degree and role of suction in unsaturated soils behaviour: application to liquefaction

The effect of the pore fluid compressibility on liquefaction has been studied by various authors. But few papers have been published about the role of suction in cyclic behavior of unsaturated soils. Most of these works use Skempton coefficient B as a reference in terms of saturation degree to analyze their results. The use of B in experimental conditions is convenient, but is not accurate when studying liquefaction behavior, since effects of suction are neglected. In this paper, the influence of saturation degree on mechanical behavior of a soil under dynamic loads is studied. Cyclic undrained triaxial tests were performed on sand samples, under various levels of saturation. Soil-water characteristic curve was used, in order to study influence of suction. The first results confirm that when the degree of saturation decreases, the resistance increases. Initial positive suction tends to stiffen the soil. It also appears that the presence of air delays the occurrence of liquefaction, but doesn’t prevent it. Indeed, liquefaction is observed, whether the soil is saturated or not.

Solvolytic Liquefaction of Bark: Understanding the Role of Polyhydric Alcohols and Organic Solvents on Polyol Characteristics

Bark was liquefied in polyhydric alcohols of various functionality, equivalent weight, and hydroxyl type, and organic solvents of varying polarity to determine how these features impact liquefaction behavior and polyol characteristics. It was found that the liquefaction yield was highly tunable with the use of polyhydric alcohols with primary hydroxyl groups, with low equivalent weight alcohols providing the highest liquefaction yield (59.3%). This showed that the highly polar hydroxyls (primary) and short chains created a highly protic solvent that improved conversion and protected the biopolymers from degradation. This was corroborated by 1H NMR analysis that indicated a greater amount of sugar degradation products were observed when polyhydric alcohols with secondary hydroxyl groups were used. Regarding organic solvents, ketonic solvents showed the greatest increase in the liquefaction yield. The composition and carbon content analysis of the residues suggested that the highly polar carbonyl group of k...

Insight into the Effect of Granulometric Characteristics on the Static Liquefaction Susceptibility of Silty Sand Soils

Silty sands are the most common type of soil that is involved in monotonic or dynamic loading induced liquefaction. It is associated with a sudden drop of the shear strength of the soil leading to important damages to civil engineering and hydraulics structures. Therefore, it is of great importance to identify the influencing parameters on the liquefaction of soils for the purpose to develop design strategies and therefore mitigate earthquake damages due to liquefaction phenomena. Published literature indicates that particle shape and gradation are the most important parameters that would affect the liquefaction behavior of granular sandy soils. For this purpose, a series of undrained compression triaxial tests were carried out on reconstituted Chlef sand (Algeria) and Fontainebleau sand (France) samples with low plastic fines ranging from 0 to 40 % and initial relative density (Dr = 52 %) to study the liquefaction susceptibility of these soils. All the samples under study were subjected to an initial confining pressure of (\(\upsigma_{c}^{'}\) = 100 kPa). The evaluation of the obtained data indicates that the gradation and particle shape have a significant influence on the undrained shear strength (liquefaction resistance) of different silty sand soils under study. Moreover, test results confirm the existence of simple correlations between liquefaction resistance and different grading characteristics (D10, D30, D50, D60, and Cu) of the soils under consideration. New soil granulometric ratios (D10R = D10sand/D10mixture , D50R = D50sand/D50mixture, and CUR = Cusand/Cumixture) were introduced to discuss the sand–silt mixture liquefaction resistance susceptibility response. The used grading characteristics ratios (D10R, D50R and CUR) appear as pertinent parameters to predict the undrained shear strength response of the sand–silt mixtures for soil gradation under study.

Cyclic liquefaction behaviour of a moderately cemented grouted sand under repeated loading

The aim of this paper is to provide an insight into the effects of a previous cyclic history “triggering” full liquefaction on the subsequent undrained cyclic behaviour of a moderately cemented grouted sand in terms of strength, deformability and pore pressure response. The research was conducted on sand specimens stabilized by a commercial mineral based chemical grout (“Silacsol”), capable of imparting unconfined compression strength (UCS) values ranging between 500kPa and 700kPa. Monotonic shear strength parameters of treated specimens were preliminary assessed through a series of isotropically consolidated drained triaxial tests (TX-CID). Afterwards, stress-controlled undrained cyclic simple shear (SS) tests were conducted on both treated and untreated sand specimens in order to evaluate the improvement provided by the grout on the liquefaction resistance of the sand. A significant beneficial effect of the grout was observed, regardless of the initial density of the pure sand. Finally the influence of a cyclic large preshearing on the undrained cyclic behaviour of the grouted sand was investigated by subjecting the specimens to a sequence of two cyclic loadings with the same stress ratio (CSR). After the first loading in which specimens were brought to full liquefaction, they were allowed to reconsolidate in approximately K0 conditions and then subjected to the second loading. An increase in liquefaction resistance induced by cyclic history was clearly apparent on treated specimens.Excess pore pressures build-up during the first cyclic loading on treated specimens followed a different trend compared to that observed on untreated ones. A significant difference was also observed on the excess pore pressure trends developed in the second loading compared to that developed in the primary loading. A simple model for the prediction of pore water pressure build-up of grouted sands during cyclic loading is proposed.