Liquefaction Resistance Research Articles

Fabric characteristics of in situ sand with/without liquefaction verified by anisotropy of magnetic susceptibility

It is well known that fabric of sand may significantly affect mechanical behaviors and liquefaction resistance of sand. Various optical techniques are currently utilized to visualize the fabric, especially the distribution of the long axis of soil particles. However, none of these methods provides an ideal solution in laboratory tests and in situ observation. In this study, anisotropy of magnetic susceptibility (AMS) was first proposed as a convenient and efficient way to evaluate the liquefaction of clean sand. At first, investigations with scanning electron microscopy (SEM) and AMS were simultaneously conducted on two groups of soil specimens with different initial fabrics to verify the feasibility of the AMS technique. Then, 80 in situ samples were collected to analyze the feature of liquefied and non-liquefied sand layers through AMS tests. It is clearly known from the test results that the natural sedimentary fabric was destroyed during liquefaction and the fabric anisotropy was greatly changed after liquefaction. The feasibility of evaluating soil fabric using the AMS survey was verified by the laboratory tests. Furthermore, the applicability of AMS in detecting liquefied layer in situ was confirmed for the first time. • Anisotropy of magnetic susceptibility (AMS) was proposed to evaluate liquefaction. • Feasibility of AMS was verified by comparing with an optical method in laboratory. • AMS was used on in-situ samples to detect the anisotropic fabric for the first time.

Effects of membrane compliance on the normal-scale triaxial cyclic liquefaction test results of saturated coral sand

Correctly evaluating the membrane penetration and compliance effects in the element liquefaction test of saturated coral sand is important for test result applications. Therefore, the penetration volume measurement and triaxial cyclic liquefaction testing of saturated coral sand and quartz sand samples with the same grading and relative density were conducted for relatively loose and dense states, and the liquefaction resistance test results before and after membrane compliance correction were analyzed. The results showed that under the same conditions, the influence of the penetration and compliance of coral sand samples was more significant than that of the quartz sand samples. The general practice of ignoring the effect of membrane compliance in normal-scale triaxial tests is inapplicable in coral sand tests and will result in relatively unsafe analysis results.

Study on Inhibition Range of Liquefaction of Saturated Sand by Load Using a Shaking Table Test

As a novel, renewable, and efficient source of energy, offshore wind power has attracted many scholars across the globe. Studies show that offshore wind power significantly enhances the liquefaction resistance of marine saturated sand foundations exposed to seismic waves as loads. In the present study, a series of shaking table tests were conducted to study the load-induced enhancement of the liquefaction resistance of the sand. To this end, the excess pore pressures of soil mass at different buried depths were monitored in real time and the variations were analyzed. Moreover, a liquefaction constant was proposed and its influencing range was quantified. The obtained results demonstrated that load inhibits sand liquefaction at the near-end area, while it facilitates sand liquefaction at the far-end area. It is found that in soil under load at a buried depth of zero to two times the diameter, the liquefaction resistance increases linearly with the load value. Furthermore, the range of vertical inhibition and the lateral load wall end is 2.55 times and 2.36 times greater than the load diameter, respectively. The present study provides a basis to study the load-induced inhibition range of sand liquefaction, which is of significant importance for the development and optimization of offshore wind farms.

Effect of soluble salts in electrolytic manganese residue on its geotechnical characteristics

Electrolytic Manganese Residue (EMR) is a solid waste containing soluble sulfate, discharged by electrolytic manganese industries. The accumulation of EMR in ponds poses a significant hazard to both safety and the environment. This study utilized innovative geotechnical test techniques to conduct a series of tests, investigating the effect of soluble salts on the geotechnical characteristics of EMR. The results revealed that soluble sulfates had a significant impact on the geotechnical characteristics of the EMR. In particular, the infiltration of water leached away the soluble salts, causing a non-uniform particle size distribution and decreasing the shear strength, stiffness, and liquefaction resistance of the EMR. Nevertheless, an increase in the stacking density of EMR could improve its mechanical characteristics and inhibited the dissolution of soluble salts. Therefore, increasing the density of stacked EMR, ensuring the effectiveness and non-obstruction of the water interception facilities, and reducing rainwater infiltration could be effective measures to enhance the safety and reduce the environmental hazard of EMR ponds.

Analysis of the Dynamic Stability of Tailing Dams: An Experimental Study on the Dynamic Characteristics of Tailing Silt

With the improvement in tailing mining-grade requirements and in mineral processing technology, tailing materials tend to be fine-grained. Under the action of earthquakes, a tailing dam is prone to liquefaction, which endangers the safety and stability of the dam. To further explore the dynamic properties of tailing silt under cyclic stress, through a series of dynamic triaxial experiments, we investigated the growth of the hysteresis curve, the development of pore pressure, and the energy dissipation law of tailing silt. The experimental findings indicated that increasing the density of the sample significantly improves its liquefaction resistance and the pore pressure development curve can be fitted using the BiDoseResp function. At the same cyclic stress ratio, the sample’s anti-liquefaction strength did not rise monotonically with increasing confining pressure but changed variably at values near a specified low confining pressure; when the sample density rose under the same settings, the specific confining pressure reduced. We also further discussed the evolution law of the stress–strain curves of tailing silt. The results further explored the dynamic characteristics of tailing silt, which can provide some reference for the seismic design and reinforcement measures of many fine-grained tailing dams.

Understanding fabric evolution and multiple liquefaction resistance of sands in the presence of initial static shear stress

Recent field observations have shown that mainshock and subsequent aftershock events can induce multiple-liquefaction events, in which soil liquefies several times at the same site. However, the fundamental mechanism of multiple liquefaction in most previous studies is under level ground conditions, and the cyclic loading condition is symmetric under such conditions. In this study, we conduct 3D DEM simulations of multiple-liquefaction processes considering initial static shear stress. 14-sphere clumped models are used to reconstruct the realistic grain shape of Toyoura sand particles. Cyclic liquefaction and reconsolidation tests are carried out alternately five times. The soil samples with various initial static shear stresses are sheared up to different maximum shear strains in each liquefaction stage. We investigate the liquefaction behavior and volumetric compression during multiple-liquefaction stages considering initial static shear stress. In addition, the evolution of contact-based fabrics, including coordination number (Z) and degree of fabric anisotropy (ac), are analyzed during the whole liquefaction and reconsolidation tests. Furthermore, we establish the relations among contact-based fabrics (Z and ac), volumetric compression and liquefaction resistance. The results reveal that in stress reversal cases, the maximum shear strain is the governing factor that influences the multiple-liquefaction resistance. Conversely, the static shear stress becomes the dominant factor affecting the multiple-liquefaction resistance in non-stress reversal cases. Moreover, changes in multiple-liquefaction resistance are attributed to the microstructure of soils represented by Z after reconsolidation.

Liquefaction behavior of inherently anisotropic sand under cyclic simple shear: Insights from three-dimensional DEM simulations

Inherent fabric anisotropy has been widely recognized to have significant effects on the liquefaction behavior of sand. A discrete element method (DEM) study was conducted to investigate the liquefaction behavior of inherently anisotropic sand under cyclic simple shear conditions. In the DEM model, the under-compaction method was modified to generate uniform and inherently anisotropic specimens. A series of DEM simulations of undrained cyclic simple shear tests were performed to investigate the effects of bedding plane angles with a full spectrum ranging from −90° to +90°. The relative magnitudes of the three effective normal stress components were compared and analyzed. The internal structure evolution was quantified through a contact-normal-based fabric tensor that could describe the load-bearing structure of granular specimens. The simulation results show that the effect of bedding plane angle on the liquefaction resistance of anisotropic sand is not monotonic. For example, as the bedding plane angle of specimen increases from 0° to 90°, the liquefaction resistance first decreases and then increases, with the most detrimental scenario occurs at 45°. This could be explained by correlating the magnitudes of shear modulus with the discrepancy between the loading direction and the direction of fabric during each cycle.

Cyclic failure characteristics of silty sands with the presence of initial shear stress

Liquefaction of silty sands remains an outstanding issue since it continues to lead to catastrophic consequences in recent earthquake events. The cyclic characteristics, such as cyclic failure pattern and cyclic resistance, are the fundamental aspects of liquefaction analysis. The difficulty and uncertainty of characterization and evaluation of cyclic behavior and liquefaction resistance of silty sand mainly come from the complicated interactions of various influencing factors, such as packing density, confining pressure, initial shear stress, cyclic loading amplitude, soil properties, and soil fabric. This study presents a series of laboratory testing results to identify the cyclic failure patterns of silty sands considering different soil states, fines contents, initial static shear stress, etc. It is found that the failure patterns are related to the states of soils and the cyclic loading characteristics, i.e., the combination of initial shear stress and cyclic loading amplitude for silty sands with similar soil fabric, and that the cyclic resistance of silty sands is also a function of soil states and initial static shear stress for similar soil fabric. Critical state soil mechanics is implemented to characterize the cyclic failure patterns and cyclic resistance. Implications of the present study to the existing liquefaction assessment methods are also discussed.

Constitutive modelling of fabric effect on sand liquefaction

Sand liquefaction under static and dynamic loading can cause failure of embankments, slopes, bridges and other important infrastructure. Sand liquefaction in the seabed can also cause submarine landslides and tsunamis. Fabric anisotropy related to the internal soil structure such as particle orientation, force network and void space is found to have profound influence on sand liquefaction. A constitutive model accounting for the effect of anisotropy on sand liquefaction is proposed. Evolution of fabric anisotropy during loading is considered according to the anisotropic critical state theory for sand. The model has been validated by extensive test results on Toyoura sand with different initial densities and stress states. The effect of sample preparation method on sand liquefaction is qualitatively analysed. The model has been used to investigate the response of a sand ground under earthquake loading. It is shown that sand with horizontal bedding plane has the highest resistance to liquefaction when the sand deposit is anisotropic, which is consistent with the centrifuge test results. The initial degree of fabric anisotropy has a more significant influence on the liquefaction resistance. Sand with more anisotropic fabric that can be caused by previous loading history or compaction methods has lower liquefaction resistance.

Pre- and Post-Liquefaction Behaviors of Manufactured Sand Considering the Particle Shape and Stress History Effects

As the substitution of natural quartz sand (QS), manufactured sand (MS) is highly demanded in the filling and reclamation of foundations in geotechnical engineering, which may be subjected to cyclic shear stresses induced by wave, seismic, and traffic loadings. One of the noticeable distinctions between MS and QS is their particle shape, which has a significant effect on their shear and liquefaction behaviors under the monotonic and cyclic shear stresses, and needs to be further investigated. In this study, the particle shapes of MS and QS were quantitatively characterized by metallurgical microscope tests and digital image processing. Their pre- and post-liquefaction behaviors were evaluated by a series of direct shear tests, cyclic simple shear tests (CSS), and post-liquefaction monotonic shear tests (PMS). The results show that in the CSS test, samples with irregular particles showed stronger liquefaction and shear resistances, indicating that MS was more stable under cyclic shear loadings. In the PMS tests, it was found that the liquefaction and shear resistances of the samples not only increased with the increasing particle irregularity but also with the increasing shear amplitude in the pre-liquefaction stage. Furthermore, quantitative relationships between the particle shape, shear history, and indexes of shear and liquefaction behaviors of the samples were proposed by regression analysis. The research findings could guide the application of MS in offshore and foundation engineering and provide a reference for the selection of MS and its foundation design.

Enhancing the seismic performance of piles in liquefiable soils by slag powder

Case studies show that earthquake-induced soil liquefaction can cause large lateral deformation of piles, leading to bridge damage. In this study, an iron and steel manufacturing by-product, slag powder, was utilized for the first time to mitigate soil liquefaction, thereby reducing the lateral deformation of piles during earthquakes. First, the liquefaction resistance of soil improved by slag powder was analyzed by cyclic triaxial tests. The results indicate that as the slag powder content increased, the soil liquefaction resistance increased. When the cyclic stress ratio is 0.2, the number of liquefaction cycles of the reinforced soil increases by 30 compared with that of the unreinforced soil. Second, a numerical modeling method of slag powder reinforced sand was proposed and validated by the cyclic triaxial test results. Third, the seismic response of piles in liquefiable soils enhanced by slag powder was evaluated using finite element analyses, and slag powder was determined to be effective in decreasing the lateral deformation of piles in liquefiable soils, the maximum displacement of the pile was reduced by 45 %. Last, an empirical formula that can easily evaluate the mitigation effect of slag powder on the lateral deformation of piles is proposed and verified by the results of finite element analysis.

Effects of non-plastic fines on liquefaction properties of saturated silt using discrete element modeling

This paper presents a numerical investigation using the three-dimensional discrete element method (DEM) to evaluate the macro-scale properties of saturated silt in a cyclic triaxial test. The three-dimensional particle model generated based on scanning electron microscopy (SEM) images of silt was imported into the discrete element program PFC3D and a rigid block model with different fines content was established. The effect of non-plastic fines content on the liquefaction properties of silty rigid block model was studied. The DEM results show that: (1) In the initial stage of dynamic stress loading, the axial strain of the sample develops slowly, and the stress-strain hysteresis loops almost overlap. With the increase of the number of cycles, the axial strain fluctuates violently, and the hysteresis loop becomes larger and develops toward the transverse axis. After the initial liquefaction, the dynamic elastic modulus and strength of the sample decrease significantly. (2) When the fines content increases from 0 to 30%, the liquefaction resistance of silt decrease with the increase of fines content. When the fines content increases from 30% to 100%, the liquefaction resistance of silt increases with the increase of fines content. (3) Under the same cyclic stress ratio, the number of cycles required for silt to liquefy decreases initially and then increases with the increase of fines content, and the critical fines content is 30%. The DEM results were compared with experimental results from the laboratory cyclic triaxial tests to provide insights into the underlying mechanism that governs the effects of fines content value on the liquefaction properties of silt.

Numerical Investigation of Liquefaction Resistance of Buried Pipelines with Sand-Tire Mixture Using Critical State Two-Surface Plasticity Model

Numerical Investigation of Liquefaction Resistance of Buried Pipelines with Sand-Tire Mixture Using Critical State Two-Surface Plasticity Model

Liquefaction triggering of non-saturated sandy soils

In saturated sandy soils liquefaction triggering is generally well-identified according to stress or strain criteria. On the contrary, the attainment of liquefaction in non-saturated sandy soils is still a cause of discussion in the scientific community. Even if the liquefaction resistance of non-saturated soils is higher than that of saturated ones, these soils may liquefy, as well. The increasing interest for cyclically mechanical behaviour of non-saturated sandy soils is due to the fact that desaturation or induced partial saturation can be used as useful mitigation techniques against soil liquefaction. Therefore, it is important to define, as accurately as possible, the attainment of liquefaction, on which depends the estimation of liquefaction resistance. The relevance of the apparent viscosity as a physically based parameter for the correct identification of the liquefaction triggering for fully saturated soils has been already demonstrated. In this paper, the viscous triggering approach has been used for non-saturated soils, processing some cyclic triaxial tests carried out on different sandy soils. The results confirm the reliability of the apparent viscosity as a liquefaction triggering parameter, showing a tight correlation with the strain liquefaction triggering criterion. Therefore, strain criterion should be preferred in non-saturated sandy soils.

Evaluation of Liquefaction Possibility of Ground Based on Grain Size Distribution and Soil Plasticity

Interest in liquefaction has increased owing to the increasing occurrence of liquefaction in the country. According to previous studies, factors that influence liquefaction include the grain size distribution, plasticity, relative density, overconsolidation ratio, and confining conditions. In this study, the liquefaction possibility was evaluated based on grain size distribution and soil plasticity. Based on the grain size distribution, a clear correlation between the liquefaction resistance of the two samples could not be identified because both samples showed similar grain size distributions. In contrast, in terms of soil plasticity, the liquefaction resistance value increased with increasing plasticity index value. These results indicate that soil plasticity has a significant effect at a similar grain size distribution.

Monotonic and cyclic undrained behaviour and liquefaction resistance of pumiceous, non-plastic sandy silt

Experimental data related to the mechanical behaviour of crushable pumiceous soils are limited compared with those for hard-grained soils. The main focus of previous studies has been on pumiceous sands, whereas pumiceous silts have not been investigated to date. In this paper, several series of monotonic and cyclic triaxial tests were performed to investigate the undrained behaviour and liquefaction resistance of a natural volcanic-ash derived, non-plastic pumiceous silt from northern New Zealand. Particle crushing due to sample reconstitution and triaxial testing was analysed by quantifying the changes in grain-size parameters and pumice contents. The main results can be summarized as follows. (1) The pumiceous silt showed a contractive response, even at medium to high relative densities, leading to high flow liquefaction susceptibility. (2) When subjected to cyclic undrained loading, the silt exhibited similar trends in terms of excess pore water pressure and axial strain accumulation to those established for hard-grained soils as opposed to those for pumiceous sands. (3) The liquefaction resistance of both medium-dense and dense samples was within the lower range compared to published cyclic resistance curves of both hard-grained soils and pumiceous sands. (4) The material did not undergo significant particle crushing after testing. Result (4) was considered to be the main factor that contributed to the fact that, in general, the cyclic undrained behaviour of the pumiceous silt was close to the trends established for those of hard-grained soils.

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 Liquefaction Characteristics of Saturated Sands Mixed with Fly Ash and Tire Crumb Rubber

The liquefaction of saturated sandy soils during dynamic loading can inflict excessive damage on the structures, leading to significant human and economic losses. Recycling and reusing industrial waste materials may offer a sustainable and economic solution to this problem. This study investigates the influence of two waste materials, namely, recycled fly ash and tire crumb rubber, on the liquefaction characteristics of sand. For this purpose, loose and medium-dense triaxial specimens were prepared using sand–fly ash mixtures containing 0–40% of fly ash and sand–tire crumb rubber mixtures containing 0–30% of crumb rubber. The liquefaction characteristics of the specimens were examined through a series of stress-controlled, undrained, dynamic triaxial tests. The tests were conducted at 1 Hz loading frequency and under initial effective confining stresses of 50 and 100 kPa. The experimental results showed that, at a similar relative density, the liquefaction resistance of the sand–fly ash specimens decreased as the fly ash content (FA) increased up to about 20%; then, it slightly increased until FA reached 40%. Sand-only specimens showed greater liquefaction resistance than sand–fly ash specimens. The liquefaction resistance of the sand–tire crumb rubber specimens was enhanced by increasing the rubber content (RC) in the mixtures. It was found that the increasing liquefaction resistance of sand with the addition of tire crumb rubber was more noticeable under higher confining stresses.

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.

Experimental study on liquefaction characteristics of saturated marine coral sand based on dissipated energy evaluation

The liquefaction of saturated marine coral sand is of a great issue for the safety of ocean engineering. A series of undrained cyclic torsional shear tests on saturated coral sand are carried out to further explore the liquefaction characteristics of coral sand. Based on the energy method, the effects of relative density (D r), effective mean principal stress (), and cyclic stress ratio (CSR) on undrained responses of saturated coral sand are investigated. Two failure criteria are discussed to evaluate the dissipated energy required to cause initial liquefaction (W l). The test results show that the W l is significantly affected by D r and The generation patterns of excess pore water pressure (EPWP) and single amplitude torsional strain amplitude (γ SA) along with cumulative dissipated energy (W c) are described, and the unified generation model of both u e and γ SA along with W c are established. The liquefaction resistance curves for various D r and are strongly related to W l. Analyzing the cumulative dissipated energy required to trigger liquefaction, a modified stress level index termed CSR e is proposed to normalize the liquefaction resistance curves of saturated coral sand under different D r and The test data in literature also verify the applicability of CSR e.