Cyclic Liquefaction Resistance Research Articles

Effect of the Interaction of Fines and Granular Particles on Cyclic Liquefaction Resistance Using the Equivalent Granular Void Ratio and Capacity Energy Approach

Effect of the Interaction of Fines and Granular Particles on Cyclic Liquefaction Resistance Using the Equivalent Granular Void Ratio and Capacity Energy Approach

Cyclic liquefaction resistance of MICP- and EICP-treated sand in simple shear conditions: a benchmarking with the critical state of untreated sand

AbstractIn the present study, the undrained cyclic behaviour of biotreated sands using microbial and enzyme-induced carbonate precipitation was investigated for a wide range of initial void ratio after consolidation ($$e_{0}$$ e 0 ), initial effective normal stress ($$\sigma^{\prime }_{{{\text{N}}_{0} }}$$ σ N 0 ′ ) and calcium carbonate content (CC) under direct simple shear (DSS) testing conditions. The critical state soil mechanics framework for untreated sand was first established using a series of drained and undrained (constant volume) tests, which served as a benchmark for evaluating the undrained cyclic liquefaction behaviour of untreated and biotreated sands. The results indicated that the modified initial state parameter ($$\psi_{{{\text{m}}_{{0}} }}$$ ψ m 0 ) in DSS condition showed a good correlation with instability states and phase transformation under monotonic shearing. In undrained cyclic DSS loading condition, samples displayed cyclic mobility indicated by an abrupt accumulation of large strain or $$\sigma^{\prime }_{{N_{0} }}$$ σ N 0 ′ transiently reaching zero or a sudden build-up of excess pore water pressure. The linkage between static and cyclic liquefaction was established for untreated and biotreated sand specimens based on the equivalence of characteristic soil states. The number of cycles before liquefaction (NL) for the biotreated sand specimens was mainly controlled by the cyclic stress ratio, $$e_{0}$$ e 0 , $$\sigma^{\prime }_{{{\text{N}}_{{0}} }}$$ σ N 0 ′ and CC. For a similar initial state prior to undrained cyclic loading, the biotreated specimens required a larger NL compared to the untreated sand. The cyclic resistance ratio at NL = 15 (CRR15) increased with decreasing $$\psi_{{{\text{m}}_{{0}} }}$$ ψ m 0 for the untreated sand, while the CRR15 for biotreated sand increased with increasing CC and decreasing $$\sigma^{\prime }_{{N_{0} }}$$ σ N 0 ′ .

Effect of particle shape on cyclic liquefaction resistance of granular materials

Effect of particle shape on cyclic liquefaction resistance of granular materials

Model prediction of cyclic liquefaction resistance of gassy soils

Model prediction of cyclic liquefaction resistance of gassy soils

Experimental Study on Liquefaction Characteristics of Coral Gravelly Soils with Different Particle Size Distributions

Many laboratory studies have shown that particle size distribution (PSD) affects the liquefaction susceptibility of granular materials. However, few studies have focused on the impact of PSD on coral particles. In this study, two different soil families were prepared: one with three levels of mean particle size (D50) with identical uniformity coefficient (Cu)and the other with four levels of Cu with the same D50 for coral gravelly soils. In addition, a series of undrained cyclic triaxial tests were conducted on coral gravelly particles with two groups of PSDs at a relative density of 40% and an adequate confining pressure of 100 kPa. The test results indicated that D50 with identical Cu can affect the undrained cyclic behavior of coral gravelly particles. In contrast, Cu with identical D50 does not impact the undrained cyclic behavior of coral gravelly particles. The developing pore water pressure was uniform when the sample was subjected to the same cyclic loading. For samples with changing D50 values of 2.35, 4.70, and 7.05 mm, increasing D50 improved the cyclic liquefaction resistance. For samples with changing Cu, increasing Cu in the range of 1.06–5.00 first increased and then decreased the liquefaction resistance.

Improvement of cyclic liquefaction resistance induced by partial saturation: An interpretation using wave-based approaches

Methods to estimate the liquefaction resistance in sandy soils have been proposed in the literature, involving correlations between cyclic resistance ratio and seismic wave velocities measured by in situ and laboratory tests. However, the applicability of these correlations has not been validated in sands improved with the induction of partial saturation. This study addresses the assessment of cyclic liquefaction resistance improvement induced by partial saturation using wave-based approaches. For this purpose, an experimental plan comprising cyclic triaxial and bender elements was carried out in a Portuguese natural sand. The studied soil is TP-Lisbon sand, a historically liquefiable soil collected in the ‘Terreiro do Paço’ site — next to the Tagus River in the centre of Lisbon. Notwithstanding, the results presented herein are compared against other liquefiable sands from Japan. The induced partial saturation was controlled by P-wave velocity measurements, which were contrasted against theoretical predictions performed in the light of Biot’s theory. The results confirmed the increase in liquefaction resistance by inducing partial saturation. Experimental results revealed that P-wave velocity provides a reliable prediction of liquefaction resistance in partially saturated conditions rather than S-wave velocity. The suitableness of these approaches was attributed to the presence of occluded air bubbles in partially saturated soils, which can be detected by the P-wave and not by the S-wave.

Experimental study on dynamic behavior of polyacrylamide-reinforced tailings.

Earthquakes are a significant factor that contributes to tailings dam failure. Generally, the seismic stability of a tailings dam can be increased by improving the dynamic properties of tailings. The dynamic properties of tailings can be improved effectively using polymers. In this study, the dynamic properties of polyacrylamide-reinforced tailings were investigated via a sequence of dynamic triaxial tests. The content of polyacrylamide in the test sample was 0.3%. Test results show that the cyclic liquefaction resistance, initial dynamic shear modulus, dynamic shear modulus, and dynamic shear modulus ratio of polyacrylamide-reinforced tailings were slightly greater than those of unreinforced tailings. The damping ratio of polyacrylamide-reinforced tailings was lower than that of unreinforced tailings when the dynamic shear strain exceeded 0.038%. The increase in the dynamic pore water pressure of polyacrylamide-reinforced tailings during cyclic loading decelerated significantly compared with that of unreinforced tailings. The revised Zeng model can effectively described the changes in dynamic pore-water pressure of unreinforced and polyacrylamide-reinforced tailings. The polyacrylamide can improve the structural stability of the tailings specimen and also improve the dynamic properties of the tailings, thereby enhancing the seismic stability of the tailings dam.

Exploring packing density, critical state, and liquefaction resistance of sand-fines mixture using DEM

A series of monotonic and cyclic triaxial shearing tests are simulated by discrete element method (DEM) to explore packing density, critical state, and liquefaction resistance of sand-fines binary mixtures. It is found that there is a threshold fines content (FCth) that makes void ratio reach the minimum value and it is affected by the relative density of the mixture. A unique critical state line (CSL) is obtained in equivalent skeleton void ratio-mean effective stress (e*-p') plane regardless of the fines content. The critical stress ratio of the mixture slightly increases as fines content increases, and its average value is around 1.20. The e* and ψe* (state parameter based on e*) can unifiedly characterize the cyclic liquefaction resistance of the mixtures with different fines contents. The active particles of binary mixtures that participate in the force chains are explored from a microscope perspective. It reveals that there is a unique micro CSL in the mechanical coordination number-mean effective stress (MCN-p') plane despite of fines contents, and the micro state parameter (ψMCN) can also successfully and unifiedly characterize the cyclic liquefaction resistance of sand-fines mixtures.

Effect of coefficient of uniformity on cyclic liquefaction resistance of granular materials

Using three-dimensional discrete element method, we analyze the particle size distribution (PSD) effect on the cyclic liquefaction resistance of spherical particle assemblies. For the same mean particle size and log-linear type PSD, the coefficient of uniformity (Cu) is chosen as a descriptor of the PSD. Samples with five levels of Cu are isotropically compressed to the same pressure and two relative densities (Dr) informed by the maximum and minimum achieved void ratios determined for each Cu. The ten samples are subjected to constant volume cyclic simple shearing at different cyclic stress ratios until reaching initial liquefaction, in 56 simulations. The simulations suggest that at each Dr the evolution pattern of excess pore pressure ratio against the number of loading cycles normalized by the number of cycles to liquefaction is minimally affected by the Cu. For the samples with lower Dr, increasing the Cu in the range 1–3 first increases and then decreases the liquefaction resistance; this trend reverses at the higher Dr. Two critical state parameters based on the void ratio and the coordination number at the pre-shearing state of the samples correlate well with the cyclic liquefaction resistance for the ranges of Cu and Dr considered in this study.

Energy-based assessment of cyclic liquefaction behavior of clean and silty sand under sustained initial stress conditions

In practical engineering, sand deposits containing some finer particles usually sustain an initial static shear stress. This study investigates the sustained initial stress effect on liquefaction response of saturated sand through conducting cyclic undrained triaxial tests. The obtained response of sand samples containing a small amount of silty fines is compared to that of clean sand under similar relative densities. The results exhibit that various stress conditions result in two response patterns named as cyclic mobility and residual deformation accumulation. It is shown that the addition of silty fines can either enhance or reduce the cyclic liquefaction resistance of sand, depending on the fines content, while the sustained initial stress plays a beneficial role in resisting cyclic failure for samples with or without the addition of fines under otherwise identical testing conditions. It is also found that the dissipated energy accumulated in both the silty and clean sand follows a power-law relationship to the generated residual pore pressure during cyclic loading. A unified relationship is further established between the liquefaction resistance and dissipated energy, which may be useful for developing an energy-based assessment of in-situ soils using strength data from laboratory experiments.

Cyclic liquefaction resistance of sand under a constant inflow rate

Cyclic resistance curves, derived through undrained element tests, are central to the study of liquefaction. Their use implies that water drainage is negligible during an earthquake. Nevertheless, a growing body of evidence suggests that this hypothesis is not realistic. In proximity to the interface of a liquefiable layer with an overlying lower permeability layer, upwards water flow can lead to localised, co-seismic pore volume increase. The aim of this paper is to quantify the effects of pore volume increase on cyclic resistance curves. Cyclic triaxial experiments are presented, performed under undrained conditions and under conditions of volumetric expansion. A constant inflow rate is chosen for the sake of simplicity. Results show that even small inflow rates have a detrimental effect on cyclic resistance. A simplified methodology is developed, which can estimate cyclic resistance under constant water inflow rates, by assuming a superposition of isotropic unloading and undrained cyclic shearing. The results presented add to increasing evidence on how current liquefaction susceptibility assessments might not be conservative for layered deposits. In addition, they highlight significant aspects of soil response under partially drained conditions.

Influence of plastic fines content on the liquefaction susceptibility of sands: cyclic loading

The paper presents an experimental study on the effect of plastic fines content on the undrained behavior and liquefaction susceptibility of sand-fines mixtures under cyclic loading. The results of undrained cyclic triaxial tests conducted on mixtures of Hostun sand with varying amounts (0–20%) and types (kaolin and calcigel bentonite) of plastic fines are presented. The specimens were prepared with different initial densities using the moist tamping method, consolidated at the same isotropic effective stress of 100 kPa and subjected to different deviatoric stress amplitudes. From the experimental observations, it was found that sand-clay mixtures with 10% or 20% clay content showed a lower cyclic liquefaction resistance than pure sand. Furthermore, the reduction in the cyclic stress ratio resulting in liquefaction after twenty cycles was found larger for sand-kaolin mixtures than for the sand-calcigel ones. Possible explanations are provided.

Using different state parameters for characterizing undrained static and cyclic behavior of sand with non-plastic fines

An experimental study was undertaken to identify the most suitable state index to be introduced for predicting both undrained static and cyclic strength of sand with non-plastic fines. The experimental work was based on an extensive program that includes 41 undrained monotonic triaxial compression tests and 78 cyclic simple shear tests. The respective critical state lines (CSLs) of the mixtures were used to define several state indices, namely state parameter (Ψ), pressure index (Ip) and modified state parameter (Ψm). Using the concept of equivalent granular void ratio, e*, a modified equivalent granular state parameter (Ψ*) was also introduced in terms of e*. The relationships of key features of undrained monotonic and cyclic behavior (i.e. liquefaction potential, instability stress ratio, normalized critical state resistance and cyclic liquefaction resistance) with the state indices were defined and discussed. The results showed that Ψ*, among others, could be used for characterizing and modeling both undrained static and cyclic features of tested soils more effectively. The derived correlations in terms of Ψ* appear to work very well, regardless of fines content, stress level and density state.

Cyclic Liquefaction Resistance of an Alluvial Natural Sand: A Comparison between Fully and Partially Saturated Conditions

Earthquake-induced liquefaction is one of the major causes of building damage as it decreases the strength and stiffness of soil. The liquefaction resistance of soils increases significantly as the degree of saturation decreases, making soil desaturation an effective measure for the mitigation of this phenomenon. This paper presents a comparative analysis of liquefaction resistance of an alluvial sand from Aveiro (Portugal) under fully and partially saturated conditions. For this purpose, an in situ characterisation based on CPTu and a laboratory series of cyclic triaxial tests were carried out. The cyclic triaxial tests were conducted under undrained conditions on remoulded specimens with different degrees of saturation, including the full saturation. On the other hand, the triaxial apparatus was instrumented with Hall-effect transducers to accurately measure the strains during all testing phases. In addition, it was equipped with piezoelectric transducers to measure seismic waves velocities, namely P-wave velocity, for evaluation of the saturation level of the specimen in parallel with the Skempton’s B parameter. Hence, relations between the B-value, and P-wave velocity and cyclic strength resistance are presented. The number of cycles to trigger liquefaction, considering the pore pressure build-up criterion, is presented for the different degrees of saturation. Results confirmed the increase in liquefaction resistance for lower degrees of saturation in this soil.

Combined effect of fines content and uniformity coefficient on cyclic liquefaction resistance of silty sands

Cyclic liquefaction of silty sands remains to be very intriguing for both research and practice. Even though many factors are known to influence the liquefaction resistance of sands, the effect of fines content is perhaps one of the most studied yet still a controversial one. Effect of grain size distribution by means of uniformity coefficient is also studied in literature but not as much as fines content influence. Moreover, to date, no clear relationship has been established between the uniformity coefficient and cyclic liquefaction resistance of clean or silty sands. This study adopts a distinct methodology by considering the effects of fines content and uniformity coefficient together, which were typically considered separately as two isolated parameters in previous studies (i.e., typically, only one of them was considered or focused). A series of constant volume cyclic direct simple shear (CDSS) tests were performed on mixtures of two base sands and four non-plastic silts at different fines contents, which also enabled authors to observe the liquefaction response of silty sands with different gradations. Based on the analysis, a new equation was developed which predicts the cyclic liquefaction resistance of silty sand by considering the uniformity coefficients of the sand (CUsand) and silt (CUsilt) fractions forming the soil together with its fines content (FC). The proposed equation was also demonstrated to work very well on six distinct silty sands having different gradations and fines contents from literature. The level of the combined influence of fines content and uniformity coefficient on cyclic liquefaction resistance of silty sands is also shown to be considerably affected by the magnitude of relative density. Practical implications and limitations of the new equation are discussed as well.

Assessment of the loading waveform on the cyclic liquefaction resistance with Hostun 31 sand

This paper was aimed at highlighting the impact of loading waveforms on the cyclic liquefaction resistance of sand. The test specimens were reclaimed by the dry tamping method with Hostun 31 sand, and the density of sand matrix was controlled to be 0.70. Three sets of undrained cyclic triaxial tests were performed by altering the loading waveforms as follows: triangular, sine and rectangular waves. The impact of the loading waveform was experimentally observed as axial cyclic stress was applied. Under the same amplitude of loading, it was found that the rectangular wave led to the most severe liquefaction as a result of greater imposed force acting for a longer duration. The triangular wave led to the lowest liquefaction softening, and the sine wave was the case in between. Consequently, in terms of the cyclic strength curves, diverse curves related to the imposed waveform were observed, and the curve for rectangular wave was located in the lowest part of the graph, thereby reconfirming its higher liquefaction potential. An in-depth analysis of the dynamic properties suggested that the development of the damping ratio with the progression of shearing is intrinsic for a given sand fabric under a certain initial confining stress. A unique relationship between the damping ratio and the amplitude of shear strain could be roughly established. However, the number of cycles required to trigger a certain level of shear strain remained a function of the amplitude and waveform. A novel parameter was proposed in this paper on the basis of the Arias intensity in order to unify the sand liquefaction response. Compared with the conventional method, one of its advantages is its ability to express the combined influence of the amplitude and waveform through a time-integral for a given imposed loading.

Liquefaction resistance of Christchurch sandy soils from direct simple shear tests

A series of cyclic direct simple shear tests are performed to investigate the liquefaction resistance of sandy soils from Christchurch, New Zealand. The study focuses on the combined effects of soil density and fines content on liquefaction resistance of sandy soils. Two sands, a non-plastic silt, and their mixtures prepared at different fines contents are tested at two sets of relative densities. Test specimens are reconstituted using a procedure for water sedimentation, yielding soil fabric and soil structure resembling those of fluvial soil deposits. Differences are observed between the two host sands in the sensitivity of the cyclic liquefaction resistance to changes in relative density. Differences are also seen in the effects of the addition of fines to the liquefaction resistances of the two sands. Monotonic undrained direct simple shear tests are employed to explore an interpretation of the liquefaction resistance of the tested soils within the critical state framework. The state-concept interpretation provides more consistent quantification of the effects of initial state on the liquefaction resistance; however, the relationship between the state parameter and liquefaction resistance is soil dependent. The results of cyclic direct simple shear tests for soils containing up to 30% fines show reasonably consistent liquefaction resistances relative to estimates from empirical CPT-based liquefaction triggering relationships.

Liquefaction resistance behaviours of gravel steel slag

Due to the continuous scarcity of sand and gravel under environmental protection policies, a new geo-backfill material with the good liquefaction resistance is urgently needed. Steel slag is a kind of industrial solid waste. The aged eight-month steel slag usually could be used as backfill material. It is important to investigate the liquefaction resistance behaviours of steel slag. According to the soil classification method, the waste steel slag is also divided into gravel steel slag, coarse steel slag and fine steel slag. Dynamic triaxial tests were carried out to investigate the liquefaction resistance of gravel steel slag in the paper by considering the effects of consolidation stress ratio, loading frequency, confining pressure and gravel-size particle contents. The variations of pore water pressure and cyclic shear resistance were analysed. The calculation model of pore water pressure of saturated sand proposed by Seed and Finn could be applied to analyse the dynamic pore water pressure development of gravel steel slag. Compared with conventional soils, the cyclic liquefaction resistance of gravel steel slag is better than that of fine sand, gravel soil, sand-gravel soils and sand pebbles. Gravel steel slag can be used to replace some conventional cohesionless soils as a geo-backfill material.

Effect of fine particles on cyclic liquefaction resistance of sands

ABSTRACT This paper presents an experimental study that investigates the influence of the fines on the initiation of instability of sands under cyclic loading. The materials used for this study and the experimental device are first presented, then the results of typical liquefaction tests for both loose and medium dense specimens are presented with emphasis on the exhibited behaviour. Loose samples have shown a total liquefaction phenomenon however the cyclic mobility phenomenon was initiated for medium dense samples. The results of a series of cyclic undrained tests that were done with the aid of a triaxial apparatus for different percentages of fines are also presented and analysed. The results reveal that the increase in the non-plastic fines content lead to an increase in the liquefaction resistance of sands whereas the increase in the plastic fines lead to a decrease in the resistance to liquefaction.

Recent advances in pore water pressure and liquefaction characteristics of low plasticity silty sands subjected to cyclic loading

Low plasticity sand-silt mixtures are very common in Italy either in natural depositional environment or in man-made earth-fill, hence the knowledge of their behavior is a crucial aspect in many practical applications. Due to higher compressibility features, significant strains and strength loss may be triggered by earthquakes. The results of a laboratory-based investigation undertaken on undisturbed samples of low plasticity silty-sandy soils recovered from a bank stretch after the 2012 Emilia Romagna earthquake in Italy, when serious damages and widespread liquefaction events were observed, are herein presented. Special emphasis was given to susceptibility to liquefaction and pore water pressure response in presence of an initial static shear stress. As part of the present work, the results of undrained cyclic simple shear (CSS) tests carried out on reconstituted specimens of sand-fines mixtures, covering a range of non plastic fines contents from 0% to 40%, were used for predicting undrained cyclic resistance through the concept of equivalent granular void ratio, e*. The conceptual framework based on e* appears appropriate for streamlining the effect of fines on cyclic liquefaction resistance of these intermediate soils, provided that fines content is less than a limiting value. Since an important stage in the assessment of liquefaction potential is to predict excess pore water pressure during cyclic loading, the results of CSS tests were also utilized for analysing pore water pressure generation models of silty sands over a wide range of fines contents.