Liquefaction Potential Of Sands Research Articles

Assessment of liquefaction potential of sand distributed in the coastal area of Ninh Thuan based on SPT values

The liquefaction potential of sandy soil has been widely investigated in the world for many years, especially after the Niigata and Alaska earthquakes in 1964. In which, the SPT values were mostly used for the evaluation of liquefaction potential. In Vietnam, the potential for soil liquefaction has been recently investigated. In the coastal area of Ninh Thuan province, the sand is widely distributed and often exposed on the surface. Additionally, many wind power farms have been built in this area. Thus, it is necessary to evaluate the liquefaction potential of sand distributed in this area. In this study, the potential for sand liquefaction in the coastal area of Ninh Thuan will be evaluated based on SPT values. Two common methods for evaluation of liquefaction potential proposed by Seed and Idriss; Idriss and Boulanger were employed. The research results show that at peak ground acceleration (amax) = 0.07 g and M = 5.5, the sand in the study area is non-liquefiable (safety factor against liquefaction, FS ( 1.48). However, at amax = 0.18 g and M = 7.5, the FS varies from 0.78 to 3.66 for the Seed and Idriss method and from 0.68 to 2.05 for the Idriss and Boulanger method. In general, the FS obtained from the Seed and Idriss method is higher than that obtained from Idriss and Boulanger method. Nevertheless, this insignificantly affects the overall assessment of liquefaction potential. At amax = 0.18 g and M = 7.5, the sand distributed in the study area can be liquefied at a depth of 17 m. However, it is not liquefied when the Nspt is higher than 28 ((N1) 60cs > 20).

A predictive model for determination of sand liquefaction potential based on energy method

The prediction of liquefaction potential of sand under earthquake action is a complicated problem in civil engineering. In this study, gene expression programming (GEP) was used to establish the relationship between the capacity energy required to trigger sand liquefaction and several major parameters. By collecting 85 experimental data and six main parameters, a GEP model was established and the empirical prediction equation was obtained. Three statistical indices were used to evaluate the performance of the GEP model and 11 other existing capacity energy models. The results show that the coefficient of determination (R2), mean absolute error (MAE) and root mean squared error (RMSE) values of all datasets predicted by the GEP model are 0.924, 0.061 and 0.087, respectively. While the R2, MAE and RMSE values of all datasets of the 11 existing capacity energy models are 0.510–0.777, 0.149–0.468 and 0.196–0.653, respectively. It can be concluded that the proposed GEP model has the potential to accurately predict the capacity energy required to trigger sand liquefaction.

Investigation of sand liquefaction potential in cyclic triaxial test and some premilinary research results in Vietnam

In the world, cyclic triaxial tests are widely used to evaluate the liquefaction potential of soil and determine the cyclic parameters for seismic design. However, the application of cyclic trixial test for evaluation of soil liquefaction is still limited in Vietnam. This paper introduced the cyclic triaxial apparatus, method and testing procedure to access the liquefaction potential of sand under cyclic loading. The research on some saturated sandy soils with high fine-grained content in Vietnam showed that the research results of soil liquefaction potential is reliable. In which, the liquefaction characteristics of sand are evaluated based on the changes of stress, strain and pore water pressure according to the cyclic cycles, thereby determining the liquefaction point and liquefaction boundary for fine sandy soils at different density levels.

A numerical approach for simulation of stress-controlled cyclic shear loading in a soil column considering partial drainage

Liquefaction strength curves (LSCs) are commonly generated based on undrained stress-controlled cyclic testing to define the liquefaction potential of sands. However, these LSCs do not consider the effect of partial drainage on liquefaction potential. This is mainly because there are very limited experimental techniques to run stress-controlled tests for partially drained sands. This manuscript proposes a procedure to numerically simulate a saturated sand column with a free drainage boundary at the top (or top and bottom), accelerated horizontally at the bottom with constant acceleration cycles of duration designed to generate constant cyclic shear stress histories in the column. This is done for columns subjected to low and high overburden pressures. The paper starts with numerical simulations of a typical undrained cyclic direct simple shear, CDSS tests by applying a stepped velocity wave to a single soil element, an already established approach. This approach only works for a single element in undrained condition which is fixed at the base. Then, the proposed procedure is implemented by applying stepped acceleration time histories at the base of soil columns having one or two drainage boundaries. In these stepped acceleration runs, the durations of the acceleration cycles are controlled to achieve a partially drained stress-controlled CDSS kind-of-loading at specific elevations within the soil columns. The technique is used to show the effect of partial drainage on sand liquefaction behavior at both low and high overburden pressures. The results show that the effect of drainage is much more significant at higher overburden. The existence of both top and bottom drainage boundaries resulted in less liquefaction vulnerability, as compared to having only one drainage boundary at the top of the sand column. The results show that liquefiable sand layers in the field may be less prone to liquefaction under high overburden pressure than predicted by the current state-of-practice, which relies mainly on undrained small-scale cyclic tests.

Damping Ratio of Sand Containing Fine Particles in Cyclic Triaxial Liquefaction Tests

Sand liquefaction triggered by earthquakes is a devastating geological disaster and has emerged as an engaging topic in earthquake engineering. With an enhanced understanding of pure sand liquefaction promoted by laboratory research, there is a growing concern, following filed investigations, over the influence of fine particles on the liquefaction potential of sand containing inclusions. Efforts have been devoted to clarifying the significance of certain physical indicators (e.g., plasticity index, particle shape and gradation characteristics), and fruitful conclusions can be found in the published literature. However, the relationship between the content of fine particles and the cyclic degradation in liquefaction process seems still unclear. To fill this knowledge gap, three sets of cyclic triaxial tests were performed on various sand–fines mixtures with the dry tamping method. The experimental results revealed that (i) fine particles provided a negative contribution to the global soil structure; (ii) however, the damping ratio measured from the obtained stress–strain loops manifested its independence from the fines content during cyclic degradation. In this paper, we propose a shearing mechanism on the microscopic scale to explain the above contrasting observations. For a given soil fabric, the fine particles around sand-to-sand contact points probably break strong force chains, intensifying the threat of liquefaction. By contrast, these fines play the same role in favouring relative sliding between sand grains during both the loading and unloading stages. As the maximum stored energy and the energy loss per cycle are amplified with the same scaling factor, the damping ratio, defined as the ratio between them, should display a macroscopic invariance in triaxial tests.

Effect of Relative Density on Liquefaction Potential of Sand in Small Laboratory Machine Base Model

Effect of Relative Density on Liquefaction Potential of Sand in Small Laboratory Machine Base Model

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 of Sandy Soil Distributed in Wind Power Farms, Soc Trang Province, Vietnam

Wind power has been widely utilized and has become a safe and renewable energy source in many countries. In Vietnam, many wind power farms have been built in coastal provinces such as Soc Trang, Bac Lieu, Ninh Thuan, Binh Thuan, Ca Mau, Vung Tau, and the Central Highlands. For onshore wind power farms, the dynamic loads generated from wind and the operation of the turbine will act on soil ground and affect the long-term strength and liquefaction potential of soil, especially for sandy soil. Thus, it is necessary to investigate the potential for liquefaction of the sandy soil layer in wind power farms. In this study, the liquefaction potential of sand distributed in onshore wind power farms in Soc Trang province, Vietnam was evaluated using the undrained cyclic triaxial test. The sand specimens were remolded using dry pluviation and moist tamping methods to simulate the field density. The analysis of test results showed that the very fine sand with a loose state distributed at the depth of less than or equal to 11.5 m could be liquefied under the testing conditions. While the fine sand specimens with a dense to very dense state distributed deeper than 30 m were not liquefied under testing conditions. However, for these specimens, the pore water ratio could be increased by 11.3 to 18.6% and this increase can lead to a decrease in soil strength.

Relative density influence on the liquefaction potential of sand with fines

Liquefaction is a loss in soil’s resistance which can lead to disastrous and expensive consequences in terms of human lives and material damages, hence the interest of this laboratory study. The article explores the relative density influence in addition to the main parameter of the fines content on the liquefaction potential of soils. The study is based on a very large number of undrained monotonic triaxial tests undertaken on samples of reconstituted saturated sand and silt mixtures with 6 levels of initial relative density ranging from 15 to 90%. The materials used are levied from different level of deepness in the coastal region of Kharouba in the wilaya of Mostaganem. In this experiment, the sand-silt mixtures were separated to form the study samples. The aim of this work is, on one hand, to confirm and update the results of previous works (Bensoula et al., 2018) and on the other hand the study of the influence of relative density on the liquefaction potential of soils and the introduction of the concept of relative density threshold. The results of the tests confirm that the studied soil is most likely to be liquefied at a fines content between 0 and 30% depending on the equivalent intergranular voids and the equivalent relative density. These parameters are primordial for the characterization of soils sensitivity to liquefaction. In this study, the results showed that the resistance to liquefaction increases in a linear way with the relative density up to a threshold relative density value according to the fines content, which means that increasing the relative density improves the liquefaction resistance but only up to a threshold value of relative density given according to fines content

Liquefaction analysis of sandy soil during strong earthquake in Northern Thailand

Northern Thailand has experienced several earthquakes which led to soil liquefaction in the past few decades. Traditional methods of evaluating liquefaction potential involve standard penetration test (SPT) or cone penetration tests. This research augmented experimental results with numerical methods to evaluate the liquefaction potential of Mae Lao Sand in Chiang Rai province of northern Thailand. SPT and downhole seismic test data collected during a field investigation at the Mae Lao site were compared to a 1D site response model analysis of the site. A series of undrained monotonic and cyclic triaxial tests was conducted on Mae Lao Sand specimens with different initial void ratios and confining pressures. Cyclic triaxial test results with varying deviator stress amplitudes were used to draw liquefaction resistance curves. Results from numerical simulation of sand liquefaction were used to characterise the stress–strain-pore water pressure response of Mae Lao Sand. 1D site response analysis determined seismic responses with different geological and groundwater conditions. All put together, the results showed that pore water pressure ratio decreases with increasing sand stiffness, the thickness of a soil layer significantly increases its liquefaction potential, and in-situ conditions and groundwater depths have major influences on the liquefaction potential of sand layers.

Assessment of Soil Liquefaction Potential Based on SPT Values at Some Ground Profiles in the North Central Coast of Vietnam

The North Central Coast of Vietnam has a wide distribution of loose sand which is often exposed on the surface. The thickness changes from a few meters to over ten meters. This sand with the loose state can be sensitive to the dynamic loads, such as earthquakes, traffic load, or machine foundations. It can be liquefied under these loadings, which might destroy the ground and buildings. The Standard Penetration Test (SPT) is widely used in engineering practice and its values can be useful for the assessment of soil liquefaction potential. Thus, this article presents some ground profiles in some sites in the North Central Coast of Vietnam and determines the liquefaction potential of sand based on SPT and using three parameters, including the Factor of Safety against Liquefaction (FSLIQ), Liquefaction Potential Index (LPI), and Liquefaction Severity Number (LSN). The research results show that the FSLIQ, LPI, and LSN values depend on the depth of sand samples and the SPT values. In this study, the sand distributed from 2.0 to 18.0m with (N1)60cs value of less than 20 has high liquefaction potential with FSLIQ<1, LPI is often higher than 0.73, and LSN is often higher than 10. The results also show that many soil profiles have high liquefaction potential. These results should be considered for construction activities in this area.

A SIMPLE SHAKING TABLE TEST TO MEASURE LIQUEFACTION POTENTIAL OF PRAMBANAN AREA, YOGYAKARTA, INDONESIA

This paper presents the experimental study of liquefaction potential for sandy soil in Prambanan Area, Yogyakarta, Indonesia, which underwent liquefaction due to the Mw 6.3 Jogja Earthquake on May 27, 2006. Shaking table tests considering the variation of acceleration and shaking duration were performed to investigate the liquefaction potential of sand. The liquefaction time stages including time to start liquefaction, time to start pore pressure dissipation, and liquefaction duration were observed. The percentage of liquefaction duration increase, the excess pore water pressure ratio and the required time to generate liquefaction, and the effect of applied acceleration to cyclic stress ratio, were also presented. The results showed that the sand could undergo liquefaction under the variation of dynamic load. The variation of dynamic load significantly influenced the time stages of liquefaction, the increase of liquefaction duration percentage and cyclic stress ratio. The results also exhibited that the larger applied acceleration and the longer shaking duration means the longer liquefaction duration and the larger liquefaction potential. In general, the result could bring the recommendation to the liquefaction countermeasure for Prambanan Area.

Flow liquefaction potential of loose sand: stress path envelope and energy-based evaluation

Flow liquefaction, which is characterized by sudden collapse following the unstable behavior of saturated loose sand, may lead to the most catastrophic consequence of all liquefaction-related phenomena. This note presents a systematic experimental investigation into the flow liquefaction potential of sand under various initial and cyclic shear conditions. The cyclic flow liquefaction responses are compared with the monotonic shear results under an identical initial testing condition. It is found that the effective stress path of a monotonic test appears to envelop that of its corresponding cyclic test. The energy-based liquefaction potential evaluation indicates that the accumulative dissipated energy is uniquely correlated not only with the pore pressure and axial strain induced in sand, but also with the degraded stiffness during cyclic loading. Furthermore, the energy capacity for triggering the flow liquefaction appears to be intimately related to the cyclic resistance of sand; this signifies the potential applicability of energy-based liquefaction potential evaluation using strength data available in conventional analysis.

EVALUATING LIQUEFACTION POTENTIAL OF PUMICEOUS DEPOSITS THROUGH FIELD TESTING: CASE STUDY OF THE 1987 EDGECUMBE EARTHQUAKE

Pumice materials, which are problematic from an engineering viewpoint, are widespread in the central part of the North Island. Considering the impacts of the 2010-2011 Christchurch earthquakes, a clear understanding of their properties under earthquake loading is necessary. For example, the 1987 Edgecumbe earthquake showed evidence of localised liquefaction of sands of volcanic origin. To elucidate on this, research was undertaken to investigate whether existing empirical field-based methods to evaluate the liquefaction potential of sands, which were originally developed for hard-grained soils, are applicable to crushable pumice-rich deposits. For this purpose, two sites, one in Whakatane and another in Edgecumbe, were selected where the occurrence of liquefaction was reported following the Edgecumbe earthquake. Manifestations of soil liquefaction, such as sand boils and ejected materials, have been reported at both sites. Field tests, including cone penetration tests (CPT), shear-wave velocity profiling, and screw driving sounding (SDS) tests were performed at the sites. Then, considering estimated peak ground accelerations (PGAs) at the sites based on recorded motions and possible range of ground water table locations, liquefaction analysis was conducted at the sites using available empirical approaches. To clarify the results of the analysis, undisturbed soil samples were obtained at both sites to investigate the laboratory-derived cyclic resistance ratios and to compare with the field-estimated values. Research results clearly showed that these pumice-rich soils do not fit existing liquefaction assessment frameworks and alternate methods are necessary to characterise them.

Effect of grain shape to potential liquefaction

Earthqueke is one of the most frequent disaster in Indonesia, Earthqueke have caused losses both in terms of life and material. An earthquake also can trigger to soil liquefaction. Attention to liquefaction in Indonesia has raised after the Palu Earthquake in 2018. Liquefaction may happen in sandy soil in certain condition. Here, a series laboratory tests to study potentially liquefied in sandy soils is conducted. The liquefaction potential of sand are analyzed with the effect of the shape of the soil particles. The sandy sample is made up by special selected in three different shapes that are sharp, angular and round. Finally, it can be seen the effect of the shape of the soil grain on the liquefaction potential. The results of this study can be used to further investigation in order to mitigate the liquefaction.

Measurement of sand grain distribution to gauge liquefaction risks at six key coastal west sumateran sites

It is well known that earthquake-induced liquefaction can cause remarkable damage to buildings. A recent disaster involving liquefaction in Palu damaged buildings and infrastructure and has become the focus of many researchers. Detailed study of liquefaction is necessary in order to have a good understanding and direct mitigation efforts for the future. In this study, the liquefaction potential of sands with various grain size distributions was analyzed. The research was experimental using a laboratory sieve shaker. The samples were taken from six areas near important facilities. From this, the relationship between grain distribution and liquefaction potential could be plotted and this information could become an important input for liquefaction mitigation efforts in sandy sediment areas.

Investigation of the effect of grain size on liquefaction potential of sands

Due to the permanent damage to structures during earthquakes, soil liquefaction is an important issue in geotechnical earthquake engineering that needs to be investigated. Typical examples of soil liquefaction have been observed in many earthquakes, particularly in Alaska, Niigata (1964), San Fernando (1971), Loma Prieta (1989), Kobe (1995) and Izmit (1999) earthquakes. In this study, liquefaction behavior of uniform sands of different grain sizes was investigated by using the energy-based method. For this purpose, a total of 36 deformation-controlled tests were conducted on water-saturated samples in undrained conditions by using the cyclic simple shear test method and considering the relative density, effective stress and mean grain size parameters that affect the cumulative liquefaction energy. The results showed that as the mean grain size decreases, the liquefaction potential of the sand increases. In addition, with increasing effective stress and relative density, the resistance of sand against liquefaction decreases. Multiple regression analysis was performed on the test results and separate correlations were proposed for the samples with mean grain size of 0.11-0.26 mm and for the ones with 0.45-0.85 mm. The recommended relationships were compared to the ones existing in the literature and compatible results were obtained.

Is There any Effect of Sample Sizes on Laboratory Liquefaction Tests?

Determination of liquefaction potential of sands in laboratory; dynamic three axial, hollow cylindrical torsional shear, resonance column, bender elements and cyclic simple shear tests are used. In this study, the effect of sample size on the determination of liquefaction energy of sandy soils in cyclic simple shear test apparatus was investigated. Uniform clean sea sand was used in the study. The cell inner diameter in which the samples to be tested is placed is 50 mm. Samples were prepared three different sizes with a length/diameter (H/D) ratio of 1, 0.5 and 0.25 and four varied relative densities (Dr: 40%, 50%, 60% and 70%). The samples were subjected to 1D cyclic loading at a frequency of 0.1 Hz under 100 kPa vertical stress and 50 kPa pore pressure. Each experiment was repeated 3 times, with equivalent or closer results considered significant. According to the test results, the liquefaction energy values per volume (J/m3) of the samples of different sizes are different from each other.

Briefing: Liquefaction potential of oil-contaminated silty sands

Oil spills may occur during exploitation and transportation or can result from accidents in oil pipelines or tanks. Such spills may cause environmental and ecological problems than can lead to changes in the mechanical properties of the affected soil. A series of cyclic triaxial tests was conducted to evaluate the effects of oil contamination on the liquefaction potential of sands and silty sands. The specimens were prepared by adding silt to Firouzkooh sand at ratios of 15, 30, 35 and 40%, mixed with crude oil (contents of 4, 8 and 12%). The results indicated that the liquefaction potential increases with an increase in silt content until a silt content of 35%, when the liquefaction potential starts to decrease. It was also found that, up to 30% silt content, the silt controls the liquefaction behaviour. Furthermore, when oil contamination exceeds 8%, the liquefaction resistance starts to decline.

Liquefaction potential of sands at the Krško-Brežice field, Slovenia

The Krsko-Brežice field is one of the most seismically active areas in Slovenia. The most damaging recorded earthquake with an intensity of VIII (EMS) occurred on 29th January 1917. It caused damage and claimed two lives. In the last 100 years, 9 earthquakes with intensity higher than VI (EMS) have been recorded. At the investigated area, a top layer up to 5 m thick, consisting of recent deposit of very loose silts and sands (ML, SM, SP), covers the medium dense to dense Quaternary gravel, beneath which there are over-consolidated, uncemented Miocene silts and marls. The top layer could be prone to liquefaction, as reported for the close surroundings of Brežice, where the liquefaction phenomenon was observed during the Zagreb earthquake in 1880 and during the Kupa Valley earthquake in 1909. The paper presents the results of laboratory index tests, cyclic simple shear tests and field investigations (SPT, CPT, (S)DMT, vs measurements), which were carried out to assess the liquefaction potential of the top layer at the location of the Brežice Hydroelectric Power Plant (HPP). All results show that the top layer is prone to liquefaction for an earthquake with a 475 year return period. Cyclic simple shear test results show that the liquefaction potential of horizontal ground for an earthquake with a 475 year return period can be reduced by the densification of the top layer to at least 95% of maximum Proctor density.