Liquefaction Of Sand Research Articles

Study on Sand Liquefaction in the Anning River Area of Youjun Town

In order to find out the structural characteristics of the substance of the Quaternary, the liquefaction grade of sandy soil, the distribution of sandy soil liquefaction and the influence on the buildings and fields in the liquefaction area in the Anning River valley within the map area of Youjun Town, the liquefaction of sandy soil and pulverized soil layers distributed in the Anning River Valley is judged according to the requirements of relevant specifications. The main research means include collecting relevant engineering data in the region, arranging exploration holes on both sides of the river valley, hydrogeological investigation, etc. , obtaining the regional distribution and grade of sand and soil liquefaction through in-situ tests, indoor experiments and analysis, and drawing the sandy soil liquefaction contour sheet. The results show that the distribution of surface sandy soil in the region is mostly lenticular and interbedded, most of the sandy soil is buried deeper than 10m, and the distribution of sandy soil layers is regional from north to south. It is also ascertained that there is less sandy soil on the north side and no sandy soil layer in most of the area, the distribution of sandy soil layer on the south side is obviously concentrated, most of them are buried deeper; and the liquefaction area and the area with serious liquefaction grade are mainly concentrated in the southern part of the river valley (Yangjiaheba-Lisuo area) , which is oval-shaped and distributed along the Anning River Valley, while the liquefaction grade in the rest of the area is in the range from slight to moderate. The study of sand and soil liquefaction in this area will provide the theoretical basis for the subsequent engineering construction planning in this area.

Laboratory investigation on liquefaction of sands and cemented sand mixes

ABSTRACT Liquefaction is considered one of the most common phenomena resulting in serious damage during earthquakes. Appropriate estimation of liquefaction potential, damping characteristics and shear modulus of soil under dynamic loading is crucial for precise dynamic response analysis and soil modelling problems. The present paper emphasises the influence of relative density, confining pressure, and shear strain on the cyclic response of sand specimens. A parametric study comprising varying relative densities (35–65%), confining pressures (100–150 kPa), and shear strain (0.015–1.3%) under 1 Hz loading frequency was conducted in the laboratory. The sand samples were subjected to a series of consolidated undrained cyclic triaxial tests. It is observed that with an increase in confining pressure and relative density, the pore pressure ratio reduced; whereas an increase in pore pressure ratio was witnessed with an increase in shear strain. The influence of cement inclusion on the cyclic response of the specimens is evaluated for varying cement contents (1–4%). The addition of 4% cement considerably enhanced the strength of sand and arrested the liquefaction instigation.

Liquefaction Potential of Saturated Sand Reinforced by Cement-Grouted Micropiles: An Evolutionary Approach Based on Shaking Table Tests

Cement-grouted injections are increasingly employed as a countermeasure material against liquefaction in active seismic areas; however, there is no methodology to thoroughly and directly evaluate the liquefaction potential of saturated sand materials reinforced by the cement grout-injected micropiles. To this end, first, a series of 1 g shaking table model tests are conducted. Time histories of pore water pressures, excess pore water pressure ratios (ru), and the number of required cycles (Npeak) to liquefy the soil are obtained and modified lower and upper boundaries are suggested for the potential of liquefaction of both pure and grout-reinforced sand. Next, adopting genetic programming and the least square method in the framework of the evolutionary polynomial regression technique, high-accuracy predictive equations are developed for the estimation of rumax. Based on the results of a three-dimensional, graphical, multiple-variable parametric (MVP) analysis, and introducing the concept of the critical, boundary inclination angle, the inclination of micropiles is shown to be more effective in view of liquefaction resistivity for loose sands. Due to a lower critical boundary inclination angle, the applicability range for inclining micropiles is narrower for the medium-dense sands. MVP analyses show that the effects of a decreasing spacing ratio on decreasing rumax are amplified while micropiles are inclined.

Calibration of an elastoplastic model of sand liquefaction using the swarm intelligence with a multi-objective function

According to post-seismic observations, spectacular examples of engineering failures can be ascribed to the occurrence of sand liquefaction, where a sandy soil stratum could undergo a transient loss of shear strength and even behave as a “liquid”. Therefore, correct simulation of liquefaction response has become a challenging issue in geotechnical engineering field. In advanced elastoplastic models of sand liquefaction, certain fitting parameters have a remarkable effect on the computed results. However, the identification of these parameters, based on the experimental data, is usually intractable and sometimes follows a subjective trial-and-error procedure. For this, this paper presented a novel calibration methodology based on an optimization algorithm (particle swarm optimization (PSO)) for an advanced elastoplastic constitutive model. A multi-objective function was designed to adjust the global quality for both monotonic and cyclic triaxial simulations. To overcome computational problem probably appearing in simulation of the cyclic triaxial test, two interrupt mechanisms were designed to prevent the particles from wasting time in searching the unreasonable space of candidate solutions. The Dafalias model has been used as an example to demonstrate the main programme. With the calibrated parameters for the HN31 sand, the computed results were highly consistent with the laboratory experiments (including monotonic triaxial tests under different confining pressures and cyclic triaxial tests in two loading modes). Finally, an extension example is given for Ottawa sand F65, suggesting that the proposed platform is versatile and can be easily customized to meet different practical needs.

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.

Assessment of liquefaction potential of sand distributed in the 1 District, Ho Chi Minh city

Liquefaction of sand is not a rare geological phenomenon. When it happens, it causes great damage to people. However, 1 District, Ho Chi Minh city where despite being a leading economic and political zone of Ho Chi Minh city, where many buildings with different loads and metro lines have been and will be rebuilt, but liquefaction potential has not been assessed. This paper presents a study on liquefaction potential of sand belonging to the Pleistocene sand lithological complex of marine origin on amSQ13 in 1 District, Ho Chi Minh based on standard penetration test (SPT) with different peak ground acceleration scenarios. Research results show that, when the peak ground acceleration amax = 0.0848 g, few points in this area occur liquefaction. However, when peak ground acceleration increased, specifically amax = 0.1 g and amax= 0.15 g, there were 8% and 68% of the survey points in the area where liquefaction occurred, respectively. The study also shows that, with a depth of about 20m, liquefaction in 1 District is still possible with amax = 0.1 g and amax = 0.15 g. The research results contribute to additional references for researchers and urban spatial planning in this area.

Liquefaction characteristics in triaxial tests under various gravity environments – DEM analyses

Liquefaction of sands occurs when the effective stress becomes zero during undrained loading, and the state of liquefaction is often considered that individual particles do not transmit contact forces. In shaking table model tests, seepage flows towards the surface occur during liquefaction; this potentially maintains individual particles floated as the gravitational forces can be cancelled out by the upward seepage forces. In laboratory element tests, however, undrained conditions induce no seepage flows during liquefaction. This raises a key question of how the individual particles behave during liquefaction in element tests, and how the macroscopic mechanical response is affected due to gravity. To answer these questions, this contribution conducts a series of triaxial loading simulations using the discrete element method (DEM) considering the effect of gravity on the mechanical response of spherical particle assemblies. The results reveal that the presence of gravity affects both packing properties and liquefaction characteristics. Inter-particle contacts are maintained during liquefaction under non-zero gravity conditions. Although the liquefaction resistance is merely affected due to gravity, the stress–strain relation and stress path are measurably altered. This contribution highlights the importance of considering the potential effect of gravity when laboratory or DEM results on liquefaction phenomena are interpreted.

Performance of a Subgrade-Embankment-Seawall System Reinforced by Drainage PCC Piles and Ordinary Piles Subjected to Lateral Spreading

Coral sand is widely distributed in coastal areas and used as a soil foundation in an increasing number of projects. Historical records show that the liquefaction and lateral spreading of coral sand foundations occurred many times during earthquakes, resulting in serious geological and engineering disasters. Based on a rigid drainage pile, a PCC pile (Large Diameter Pipe Pile by using Cast-in-place Concrete) and drainage body are innovatively combined into a new drainage PCC pile, to reduce the harm caused by liquefaction and lateral spreading of the coral sand foundation. In this study, the seismic response of the subgrade-embankment-seawall system on the coral sand liquefaction site was simulated using a shaking table. The excess pore water pressure ratio, acceleration, average foundation settlement, seawall displacement, embankment deformation, and pile body bending moment of the ordinary pile foundation and new drainage PCC pile foundation under seismic loads of PGA peak ground acceleration = 0.05 g , PGA = 0.1 g , and PGA = 0.2 g on the coral sand site were analyzed and compared. Compared with ordinary pile foundations, the excess pore water pressure ratio, pile bending moment, seawall displacement, foundation settlement, and embankment deformation of the new drainage PCC pile foundation were markedly reduced, while acceleration increased, which showed that the new drainage PCC pile had a positive anti-liquefaction effect on the coral sand foundation.

Effect of fabric anisotropy on the cyclic liquefaction of sands: Insight from DEM simulations

To interpret the effects of fabric anisotropy on the cyclic liquefaction of sands, undrained cyclic triaxial tests on the vertical and horizontal specimens were simulated using the discrete element method with ellipsoidal clumps. The simulation captured the anisotropic cyclic responses of sands observed experimentally: (a) the vertical specimen is more prone to liquefaction than the horizontal one under symmetrical cyclic loading conditions; (b) the axial strain is accumulated at the extension side for the vertical specimen and at the compression side for the horizontal specimen. At the particle scale, the mechanical coordination number, redundancy index, contact-normal and particle-orientation based fabrics were investigated to provide insight into the macro response. It is found that at the onset of liquefaction, the redundancy index is equal to 1, the mechanical coordination number is equal to 3.3, and the contact-normal based fabric anisotropic variable is always negative. Furthermore, the anisotropic critical state theory was applied to investigate the relationship between the macro-mechanical behavior and the evolution of contact-normal based fabric, which facilitates the development of constitutive models for simulating cyclic liquefaction behavior of anisotropic sands.

Effect of Fines on Static Liquefaction of Sand

Effect of Fines on Static Liquefaction of Sand

Classification and Semiquantitative Evaluation of Paleoearthquake Identification From Trenches on Normal Faults: A Case Study of Holocene Paleoearthquake Events From the Northern Margin of the Hetao Basin, China

AbstractLong paleoearthquake series are crucial for understanding the recurrence patterns of active faults and evaluating the seismic hazards of faults. In this study, the first semiquantitative evaluation of paleoearthquake events from trenches was applied to normal faults, and classification criteria for identifying paleoearthquakes in trenches on normal faults are proposed to demonstrate the feasibility of semiquantitative evaluations of paleoearthquake events on normal faults. In this study, 72 paleoearthquake trench sites on normal faults around the world were analyzed, and the main indicators for identifying paleoearthquakes on normal faults include the presence of vertical offset (VO), collapse wedge (CW), fissure (FIS), buried paleosol (BP), angular unconformity (AU), upward termination (UT), and sand liquefaction (LF) features. To describe and apply this semiquantitative evaluation method for paleoearthquake events on normal faults, 33 trenches for paleoearthquakes on a fault system in the northern margin of the Hetao Basin were comprehensively analyzed to determine Holocene paleoearthquake events on the Sertengshan, Wulashan, and Daqingshan piedmont faults, and the reliability of paleoearthquake events is discussed. The integrity of the paleoearthquake events obtained was tested by the displacement limit method. The Holocene paleoearthquake recurrence on the three faults was quasiperiodic; the coefficients of variation (COVs) were 0.44, 0.58, and 0.4.

Probability Liquefaction On Silty Sand Layer On Central Jakarta

Indonesia has a strong earthquake risk. The effects of saturated silty sand liquefaction during earthquakes can be very damaging. Liquefaction is the threats to the safety of structures, and the evaluation of liquefaction potential is essential in locations with silty sand layers. Research was performed at BPJS Branch Office building project in CentralJakarta with 7 floors when conducted the substructure or deep foundation design. This research uses cone penetration test (CPT) data to evaluate the potential and probability of liquefaction. At the same time, this research also predicts the bearing capacity (Qu) of single pile embedded on silty sand layer at conditions of Non-Liquefaction (NL) and Liquefaction (L) due to an earthquake. The research results showed that silty sand layers were classified as the susceptible layers to the liquefaction potential after plotted of CPT data into the graphic from Robertson & Campanella method [1] and signed by zone A. However, bearing capacity (Qu) when condition of NL and L was only different around 10 to 11%, it can be considered that the single pile remains stable during occurrence the liquefaction and capable to support the upper structure system. This assumption is also strengthened by the analysis result of probability liquefaction (P[L]) for sand and silty sand layers, the average of (P[L]) based on the maximum earthquake acceleration (PGA) T = 50 years exists in the range < 5 % to 10 % and it can be stated that [P(L)] is very low to low [2] and it can be concluded that the sand and or silty sand layers at study area is hard to category as a liquefiable layer.

Evaluation indicators of saturation on partially saturated sand induced by microbial gas

The induced partial saturation (IPS) technique introduces a certain amount of air/gas into soil voids to mitigate sand liquefaction. The microbial desaturation method utilises biological metabolic processes which are good for environmental protection and disaster prevention. Real time monitoring and quantitative analysis of the saturation after microbial bubble generation are the first step in the field application of the IPS method. In this study, shear wave velocity measurements were taken using the pre-vibration technique through an array of accelerometers at different depths on the basis of shaking table model tests. The shear wave velocity was obtained during the desaturation of microbial gas production. The arrival time of the first wave peak increased and the shear wave velocity decreased with the decreasing saturation. The shear wave velocity decreased with the saturation, and the rate of shear wave velocity decreased when the degree of saturation reduced to 90 %. This result indicates that the shear wave speed is effective as an indicator of saturation in microbial gas production. The shear wave velocity decreases with the saturation, and the relationship between the two satisfies the exponential functions. A quantitative relationship was established between the saturation and shear wave velocity during microbial gas production. The maximum shear modulus decreases with the saturation during the gas production process. Meanwhile, the relationship between shear wave velocity and resistivity was established using resistivity meters. The resistivity value decreases with the degree of saturation. The power function relationship between resistivity and saturation was satisfied in this experiment. The explicit analysis of the saturation data at each point in the desaturation method has significant research value for field trials using high-density electrical resistivity tomography. The research results obtained in this experiment can help in the quantitatively analysis of the uniformity and effectiveness of bubble distribution in the field test application of the microbial desaturation method and provide a basis for the engineering application of the microbial desaturation method in field tests.

Study on the liquefaction characteristics of saturated sands by millisecond delay blasting

The liquefaction in saturated sands under blast loading is an important research topic in geotechnical engineering. The effect of blast loading on the liquefaction characteristics of saturated sands was studied through a large-scale millisecond delay blasting (MDB) liquefaction field test. Based on the field test, a numerical model was established by the LS-DYNA finite element program to study the propagation of blast waves and the effects of explosive mass, scaled distance, and blast delay on the liquefaction characteristics of saturated sands. The results show that there was a significant sand boiling phenomenon in saturated sands under blast loading, and high values of the excess pore water pressure ratio were observed at monitoring points during the field test. The numerical simulation results show that the scaled distance and the blast delay significantly affected the excess pore water pressure. While the blast delay increased from 110 ms to 330 ms, the excess pore water pressure of the central area can increase by more than 18%. Based on the field and numerical tests, an empirical equation is established that can take into account both the scaled distance and blast delay, which provides a theoretical basis for future large-scale liquefaction sites by MDB.

Numerical Simulation of Stiffened Granular Pile

Abstract: Granular piles are suitable for increasing soft clay's strength and consolidation properties. Stone columns offer a practical, affordable solution for enhancing the earth and are crucial for stabilizing the soil. In order to carry higher shear stresses and prevent settlement, stone columns behaved as stiff elements, which enhanced the deformability and strength characteristics of the soft type of soil. The usage of granular piles has been shown to improve slope stability, increase bearing capacity, decrease differential and total settlements, decrease sand liquefaction, and lengthen settlement times. The present study studied the effect of stiffening on the granular pile using PLAXIS 2D. Mohr-Coulomb failure criterion was considered for the stone column, expansive soil, and granular material used for stiffening. The present study results are validated with the experimental results and are in good agreement. Numerical results show that stiffening in granular piles increases the load settlement response and stress transformation to a depth of granular pile and reduces the bulging

Acoustic emission induced by sand liquefaction during vibration loading

The article deals with the study of poorly graded sand samples of different grain content subjected to liquefaction. The research results show the V-shaped behavior of the AE parameters that correspond to the three-stage sand behavior: Phase A is associated with microfractures/displacements between sand grains caused by an increase in pore pressure before the liquefaction point. Phase B (the stage of AE silence just before the liquefaction point) reflects the equality between pore pressure and stress in the confining chamber. Phase C (the stage of increase in AE parameters’ values) is explained by intense friction between sand grains during their movement caused by liquefaction. Our results show that the AE behavior before, at, and after the liquefaction point is significantly affected by the sand grain content. The change in the sand composition from the poorly graded dune sand to "extremely poorly graded sand" significantly increases the time for the creation of the liquefaction state while the coarser the sand grains become, the longer duration of vibration loading is required to reach the liquefaction state.

Improved artificial electric field algorithm based on multi-strategy and its application

Artificial electric field algorithm is a new swarm bionic optimization algorithm, which uses the interaction force of charged particles to create a mathematical model to solve the problem. In order to improve the global exploration ability and local development ability of artificial electric field algorithm, an artificial electric field algorithm based on opposition learning is proposed. The chaos strategy is used to strengthen the quality of the initial population, and the opposition learning strategy is used to increase the diversity of the population and the development ability of the algorithm. The excellent performance of the algorithm is proved by simulation experiments. The improved artificial electric field algorithm was combined with SVM to construct the sand liquefaction identification model by selecting seven measured indexes, including intensity, underground water level, overlying effective pressure, standard penetration hit number, average particle size, non-uniformity coefficient and shear stress ratio. Compared with traditional methods such as standard method and seed simplification method, the results show that IAEFA-SVM model has high prediction accuracy and provides an effective method for sand liquefaction identification

Spatial Distribution Characteristics of Microbial Mineralization in Saturated Sand Centrifuge Shaking Table Test.

Calcium carbonate induced by microorganisms can quickly fill and cement sand particles, thereby effectively reducing the potential for the liquefaction of sand. This process could represent a new green approach to the liquefaction treatment of saturated sand and has good prospects for application. However, owing to the diversity of microbial activities and the heterogenous spatiotemporal distribution of bacterial nutrient seepage in sandy soil foundations, the resultant complex distribution of calcium carbonate deposition in a sandy soil foundation can lead to differences in solidification strength and improvement effect. To understand the influence of earthquake action on the liquefaction resistance of saturated sand treated by microorganisms, and to evaluate the effect of microbial technology on sand liquefaction prevention under dynamic load, this study simulated the dynamic stress conditions of saturated sand under shear waves, using the world′s first centrifuge shaking table (R500B), which realizes horizontal and vertical two-way vibration. On the basis of spatial heterogeneity of microbial mineralization after centrifuge shaking table tests, the effect of microbial strengthening on liquefied sand was analyzed, and the spatial distribution of calcium carbonate mineralization was examined. The results showed that the distribution of microorganisms in the solidified soil exhibited obvious spatial heterogeneity with a significant edge effect. Although microbial mineralization effectively improved the liquefaction resistance of saturated sand, a sudden change in the process of calcium carbonate deposition altered the cementation of the sand with depth. Moreover, the curing strength had obvious complexity and uncertainty that directly affected the shear stiffness of the soil under dynamic load, and this constitutes one of the reasons for the degradation of shear stiffness of sand during liquefaction. The derived conclusions could be used as a reference for engineering applications of microbial treatment of a liquefiable sandy soil foundation.

Experimental Studies and Constitutive Modeling of Static Liquefaction Instability in Sand–Clay Mixtures

This paper examines static liquefaction phenomena in sand–clay mixtures from both experimental and theoretical perspectives. Consolidated undrained triaxial tests (CU tests) are implemented on a mixture of sand and clay to study the effects of initial relative density, confining pressure, and clay content on static liquefaction responses. By using the equivalent granular state parameter, a state-dependent hardening plasticity model is proposed to reproduce mechanical responses, as well as to replicate the observed static liquefaction phenomenon. In accordance with the second-order work theory, the criteria for predicting the potential instability and static liquefaction of sand–clay mixtures are obtained. The analyses show that (1) static liquefaction is prone to be promoted by low initial relative density and confining pressure; (2) even a small amount of clay particles can significantly increase the liquefaction susceptibility in loose sand–clay mixtures; (3) the proposed constitutive model can provide a satisfactory match between the test data and the simulations; and (4) even when the state of the soil is potentially unstable, soils can still remain stable unless second-order work vanishes, which indicates the inception of static liquefaction.

Sand liquefaction during the 2021 M 7.4 Maduo earthquake, China

Sand liquefaction during the 2021 M 7.4 Maduo earthquake, China