A Liquefaction Study Using ENN, CA, and Biogeography Optimized-Based ANFIS Technique

In any construction projects,assessment of liquefaction potential induced due to seismic excitation during earthquake is a critical concern.The objective of present model development is to classify and assess liquefaction potential of soil.This paper addresses Emotional Neural Network(ENN), Cultural Algorithm(CA) and biogeography optimized(BBO) based adaptive neuro-fuzzy inference system (ANFIS) for liquefaction study.The performance of neural emotional network and cultural algorithm has been also discussed. BBO-ANFIS combines the biogeography features to optimize the ANFIS parameters to achieve higher prediction accuracy.The model is trained with case history of liquefaction databases.Two parameters are used as input such as the cyclic stress ratio and standard penetration test (SPT) value.The performance of these models was assessed using different indexes i.e. sensitivity, specificity, FNR, FPR and accuracy rate.The performance of all models is compared.Among the models, the BBO-ANFIS model has been outperformed and can be adopted as new reliable technique for liquefaction study.

Liquefaction Vulnerability Analysis using N-SPT Value and Grain Size Analysis on Gumbasa Irrigation Canal in the Post-Disaster Petobo Area, Sulawesi

Strong earthquakes occurred in Central Sulawesi, Indonesia, in late 2018, causing an inheritance disaster, soil liquefaction on Gumbasa Irrigation Canal at Petobo, Sulawesi. Soil liquefaction is a phenomenon of a decreasing soil bearing capacity triggered by strong vibrations in certain soil conditions. It immediately changes the soil characteristic from solid to liquid. Liquefaction vulnerability analysis was done using Idriss-Boulanger’s simplified procedure based on SPT value in several spots. The Petobo liquefaction zone has seven boreholes, five of which are located near the Gumbasa Irrigation Canal. The soil sample at those boreholes was taken to the laboratory for further soil testing using grain size analysis. The simplified procedure is intended to calculate the safety factor using Cyclic Resistance Ratio, Cyclic Stress Ratio, and Magnitude Scaling Factor. The liquefaction vulnerability analysis resulted in the AB 1 – AB 3 area near Gumbasa Irrigation Canal, which liquefied. Meanwhile, LP 1 and LP 4 are contrary. LP 1 is located upstream of the canal, whereas LP 4 the downstream. Grain size analysis yields a consistent result that AB 1 – AB 3 soil is quite scattered inside the liquefiable constraint.

Deformation Behavior of Saturated Marine Silt under Principal Stress Rotation as Induced by Wave Loading

An experimental study aimed at providing insights into the cyclic deformation behavior of saturated marine silt under principal rotation, as induced by wave loading, is presented. Using the GDS hollow cylinder apparatus, a series of undrained tests are performed and the specimens at identical initial states are subjected to combined axial–torsional cyclic loading that imposes different levels of stress rotation. The cumulative generalized shear strain γg is used to describe the deformation of the silt under complex stress paths. The test results show that the cumulative generalized shear strain is significantly dependent on the cyclic stress ratio (CSR) and cyclic loading amplitude ratio δ. The cumulative generalized shear strain increases with the increase in CSR and decreases with the increase in δ. The development trend of γg can be well predicted through the correct Monismith model in the non-liquefaction silt, with a low error that is generally less than 10%.

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.

STABILITAS TIANG PANCANG AKIBAT LIKUIFAKSI PADA PROYEK GEDUNG SANGGALA JAKARTA

Liquefaction is an incident where the soil losses its shear strength due to increased porewater stress due to the incident of very fast cyclic loading in a short time. Liquefaction event due to earthquakes can cause structural failure of the building. In this case, the Sanggala Building Project in Jakarta exists at location of liquefaction potential susceptible area, and design analysis only uses the data of Cone Penetration Test (CPT). Stability analysis of pile due to liquefaction potential is aimed to determine the value of the factor of safety (FS) in the area, which is analyzed by comparing the value of Cyclic Stress Ratio (CSR) due to the earthquake and Cyclic Resistance Ratio (CRR) as the soil resistance to resist liquefaction potential. Based on the analysis and calculations performed, was obtained the value of FS > 1, which means actually the soil does not have the liquefaction potential. However, this study still takes into consideration the liquefaction potential as one of requirements of local regulation when the analysis of bearing capacity of pile foundation analyzed by the method of Schmertmann (1978) in a depth of 25 m and the results was indicated by 1660,27 kN for single pile and 12081,63 kN for the group piles. Furthermore, all these results from several stability calculations, the pile foundation system stable from liquefaction potential.

Cyclic soil-root mechanical interaction

<p>Plant roots have been considered to be effective to reinforce shallow soil slopes under rainfall conditions. Recent evidence from geotechnical centrifuge modelling shows that plant roots could improve earthquake-induced slope stability and reduce slope crest settlement. However, the underlying fundamental mechanisms of soil-root mechanical interaction against seismic loading are unclear. Although there has been a large volume of studies focusing on root reinforcement, cyclic soil-root mechanical interaction has rarely been investigated. Moreover, whether plant roots could reduce the liquefaction potential of rooted soil. This presentation will present some new test data and evidence about (1) cyclic root biomechanical behaviour and (2) cyclic responses of root-reinforced soil. In part (1), results of cyclic uniaxial tensile tests on roots of a wide diameter range will be presented, including any root hardening or softening and change in the size of hysteresis loops under displacement-controlled loading condition. Special attention will be paid on any observation of cyclic-induced root mechanical fatigue. In part (2), results of a comprehensive set of monotonic and cyclic triaxial tests on rooted soil will be presented. The cyclic behaviour observed will be interpreted through the monotonic behaviour observed along both the triaxial compression and extension paths. Any change in soil failure mechanism from limited flow failure to cyclic mobility due to plant roots, and how/when this change occurs at different root volume and cyclic stress ratio, will be discussed in detailed. A new attempt to interpret the liquefaction resistance through an energy-based approach will be made to evaluate the energy dissipation mechanism in rooted soils.</p>

The Effect of Cyclic Loading of Liquefaction on Palu Sands

<p>Liquefaction is a phenomenon where soil loses its strength. The phenomenon of liquefaction occurs on non-cohesive soils with medium to fine grains. The phenomenon of liquefaction occurs during an earthquake, the ground experiences shaking vibrations. Palu, Central Sulawesi, Indonesia is one of the areas affected by the liquefaction phenomenon which causes damage to infrastructure in the area. The Palu earthquake that occurred on September 28, 2018, at 18:02:44 WITA with a magnitude of M<sub>w</sub> = 7.4, centered on 26 km north of Donggala, Central Sulawesi. One aspect of the assessment for soil susceptibility to potential liquefaction is laboratory tests. One common laboratory test that can be performed is the cyclic triaxial test. The factors affecting the liquefaction resistance of saturated sand are the relative density and cyclic stress ratio (CSR). The susceptibility of each relative density (30%, 50% and 70%) of the soil experiencing liquefaction and the cyclic stress ratio (0.15, 0.20 and 0.25) will be varied to see the amount of cyclic load needed until the soil experiences liquefaction, the load frequency to represent the earthquake load is 1 Hz with sinusoidal waves. This study will test the fine sands from Palu, Central Sulawesi, Indonesia, to determine their respective behavior when the soil is given a cyclic load.</p><p>Keywords: Cyclic Triaxial, Liquefaction, Cyclic Stress Ratio, Relative Density, Fine Sands.</p>

Liquefaction and Reliquefaction Resistance of Saturated Sand Deposits Treated with Sand Compaction Piles

To mitigate liquefaction and its associated soil deformations, ground improvement techniques were adopted in field to reinforce saturated sand deposits. Sand Compaction Pile (SCP) is one such popular proven treatment to improve liquefaction resistance of sandy deposits. Installation of sand compaction piles improves soil density and rigidity which further enhance seismic resistance against liquefaction and this was well evident from past field observations. However, studies involving SCP performance during repeated shaking events were not available/limited. In this study, using 1-g uniaxial shaking table a series of shaking experiments were performed on SCP treated and untreated sand deposits having 40% and 60% relative density subjected to repeated incremental acceleration loading conditions(i.e. 0.1g – 0.4g at 5 Hz frequency).Parameters such as improvement in soil resistance and relative density, generation and dissipation of excess pore water pressures, maximum observed foundation settlement and soil displacement and variation in cyclic stress ratio were evaluated and compared. Seismic response of liquefiable sand deposits found to be improved significantly due to SCP installation together with occurrence of continuous soil densification under repeated loading. The experimental observations suggested that SCP can perform better even at repeated shaking events.