Factors affecting liquefaction of soil pdf

Nonundrained condition and strain paths an undrained condition can be represented mathematically as dedei 0 and a nonundrained condition as dedei i 0. Compositional factors that influence liquefaction susceptibility include particle size, shape and gradation. Significant factors affecting the liquefaction or cyclic mobility potential of sands during earthquakes are identified, and a simplified procedure for evaluating liquefaction potential which will take these factors into account is presented. Recent developments of soil improvement methods for seismic. Other factors affecting the liquefaction susceptibility of different soil types are discussed. The factors influencing this kind of liquefaction are studied. No correct answer many variables useful index on expected performance. It is identified that generation of pore water pres sure is the key factor affecting the liquefaction. In the different phenomenon related to the soil, the liquefaction of sandy and silty soils, as.

Soils, soil characteristics and factors affecting management. Soil liquefaction description and protection measures i. Recent developments of soil improvement methods for. These provide a base on which the active soil forming factors work or act for the development of soil. Finally, methods for improving insitu soil conditions to. The factors affecting the prefailure liquefaction are also studied. Liquefaction studies as the problem of liquefaction became important in the sixties, research was vigorously taken up and included a investigation of. If a soil layer is within 50 feet of the ground surface, it is more likely to liquefy than deeper layers. Assessment of postliquefaction consolidation settlement. Soil liquefaction an overview sciencedirect topics. This structurefooting soil interaction sfsi can cause the seismic response of a structure to be different from that of an identical structure with an assumption of an idealised fixed base. Pdf factors affecting liquefaction and cyclic mobility. Paper open access control methods and influence factors of. Jul 06, 2015 soil liquefaction seminar and ppt with pdf report.

Jan 09, 2010 influence of soil conditions on liquefaction potential 24. Liquefaction has been abundant in areas where ground water lies within 10 meters of the ground surface hussain et al. Bretz, jr, lt col, usaf 00 january 1990 final report. Soil liquefaction occurs when waterlogged soil behaves like a liquid. Some people refer to it as earthquake liquefaction. We have provided soil liquefaction seminar and ppt with pdf report.

Paper open access control methods and influence factors. Soil liquefaction describes the behavior of soils that, when loaded, suddenly go. If a soil layer is a fluvial, lacustrine or aeolian deposit of holocene age, a greater potential for liquefaction exists than for till, residual deposits, or older deposits fines content and plasticity index. Liquefaction risk assessment using geostatistics to. Liquefaction is often described in the literature as the phenomena of seismic generation of excess porewater pressures and consequent softening of granular soils.

Fundamental factors affecting liquefaction susceptibility of sands. Introduction the cyclic strength of sands and other cohesionless soils e. Land damage mapping and liquefaction potential analysis of soils. Researchers have designed various types of laminar boxes in the past.

Key factors affecting improved ground performance are the type, size, and location of the treated ground. Variations of soil liquefaction safety factors depending. Liquefaction is a phenomenon wherein a saturated mass of sand loses a large percentage of its shear resistance and flows in a manner resembling a liquid until the shear stresses acting on the mass are as low as its reduced shear resistance. New stress reduction factor for evaluating soil liquefaction. Factors affecting liquefaction potential have been studied exten. Liquefaction phenomena, stress strain behavior of sands. Model geometry and soil properties a series of numerical analysis were carried out to investigate various factors affecting the liquefaction potential of saturated sandy soil. The correlation between corrected n1, 60values and the intensity of cycling required to trigger liquefaction is also a function of fines. Many factors govern the liquefaction process for in situ soil and the the most important are intensity of earthquake and its duration, location of ground water table, soil type, soil relative density, particle size gradation, particle shape, depositional environment of soil, soil drainage conditions, cofining pressures, aging and cementation. Analysing and preventing the problems of liquefaction in soils. Liquefaction of dilating granular soils school of civil and. Liquefaction potential in a soil layer increases with decreasing fines content and plasticity of the soil. Ground improvement for liquefaction mitigation at existing. Evaluation and mitigation of liquefaction hazard for.

Soil liquefaction is a major cause of site damage to an earth dam in the. Soil characteristics age, stress history, fines, etc. Sensitivity of the derived probabilistic relationship to the key assumptions is examined, and issues affecting the application of probabilistic liquefaction triggering models in practice are discussed. This may be initiated by either monotonic loading i. The resistance of soil deposits to liquefaction is usually determined using insitu testing comprising one or more of penetration tests, such as the standard penetration test spt or the. Soil liquefaction can also exert higher pressure on retaining walls, which can cause them. Keeping in view, damages of public life and infras tructure roads, life lines, etc. Origin of cptbased methods all methods have similar origins. Liquefaction risk assessment using geostatistics to account for soil spatial variability jack w. Pdf liquefaction is a phenomenon wherein a saturated mass of sand. Liquefaction and related phenomena have been responsible for tremendous amounts of damage in historical earthquakes around the world.

Modeling soil liquefaction hazards for performancebased. Evaluation of soil liquefaction potential for level ground. Parent material it is that mass consolidated material from which the soil has formed. Ground water and degree of saturationlevel of groundwater is another factor affecting the rate of liquefaction. Dec 14, 2017 the presence of silt and clay particles has long been thought to affect the behavior of a sand under cyclic loading.

Liquefaction is most commonly observed in shallow, loose, saturated cohesionless soils subjected to strong ground motions such as during earthquakes. The traditional factors of safety were computed in addition to the computation of the factors of safety after liquefaction. Finally, methods for improving insitu soil conditions to reduce liquefaction susceptibility are discussed. Available field data concerning the liquefaction or nonliquefaction behavior of sands during earthquakes is assembled and compared with evaluations of. Ground lowering may be sufficient to make the surface close to or below the watertable, creating ponds. Liquefaction is the process that leads to a soil suddenly losing strength, most normally as a result of ground shaking during a large earthquake. The liquefaction mechanism of soil and its influencing factors have always been a vital. Seed and idriss 1967 illustrated that relative density is the main factor affecting the liquefaction strength of soil. Soil liquefaction has been observed in almost all large earthquakes, and in some cases it has caused much damage. Analysis of soils from the epicentral region of 2017. In terms of liquefaction mitigation, some relatively new concepts have been proposed such as passive site. The assessment of potential liquefaction of soil deposits at a site must consider two basic types of hazard. Several definitions of soil liquefaction are in basic agreement with this con cept.

Finally, the influence of the presence of nonplastic fines might have on the methods for. Finally, liquefaction susceptibility depends on the initial stress state and density of the soil. Soil liquefaction has attracted considerable attention from geotechnical engineering researchers over the past 35 years. Jun 18, 2018 soil liquefaction induced by earthquake shaking is also a major contributor to urban seismic risk. Standard penetration testbased probabilistic and deterministic assessment of seismic soil liquefaction potential k. Case histories each summarized to 1 data point csr7. Request pdf fundamental factors affecting liquefaction susceptibility of. Liquefaction research has been undertaken from several different perspectives, which has led to some ambiguity and inconsistency in the terminology used to describe various liquefaction related phenomena. The internal influencing factors of soil liquefaction and the external dynamic factors. A summary report, author seed, h b and arango, i and chan, c k, abstractnote the results of a threeyear research program conducted to investigate the settlement and liquefaction of sands under multidirectional shaking are evaluated. Control methods and influence factors of silt liquefaction. The more the soil is saturated the chances for it to liquefy are more. Jun 21, 2015 cyclic mobility is a liquefaction phenomenon, triggered by cyclic loading, occurring in soil deposits with static shear stresses lower than the soil strength. Soil liquefaction occurs when the effective stress shear strength of soil is reduced to essentially zero.

Passive soil forming factors the passive soil forming factors are those which represent the source of soil forming mass and conditions affecting it. Lowering of ground levels where liquefaction and soil ejection has occurred. During an earthquake, the movement of soil causes movement of structures and this structural response, in turn, influences the movement of soil. Theory criteria of liquefaction factors affecting liquefaction laboratory studies evaluation of liquefaction potential criteria of liquefaction evaluation of liquefaction hazards is the soil susceptible to liquefaction. A very simple laminar box was utilised by latha and krishna 2008. Guidelines for evaluating liquefaction hazards in nevada i. This paper presents new correlations for assessment of the likelihood of. The city of catania, in southeastern sicily, was affected by several destructive. Some factors affecting the liquefaction and flow of saturated. Soil liquefaction and related ground failures are commonly associated with large earthquakes. The liquefaction phenomenon develops mainly in loose to medium compact sandy soils due to the development of interstitial pressures induced by seismic actions. If the soil is susceptible, will liquefaction be triggered. Since liquefaction phenomena arise because of the tendency of soil grains to rearrange when sheared, any factor that prevents the movement of soil grains will increase the liquefaction resistance of a soil deposit.

The liquefaction mechanism of soil and its influencing factors have always been a and vital challenging point in liquefaction research. Criteria of soil liquefaction with spt and fines content. Liquefaction triggering assessments are often performed for individual locations, providing little information in regard to the expected spatial extent of liquefaction. Background on october, 8, 2005, kashmir area of pakistan was struck by a 7.

Some factors affecting the liquefaction and flow of. The main factors which affect liquefaction occurrence are the degree of soil compactness, particle size and degree of water saturation. Factors affecting the cyclic loading strength of soil. Translational site instability sliding, edge failure, lateral spreading, flow failure, etc. Some factors affecting the liquefaction and flow of saturated sands in. Analysing and preventing the problems of liquefaction in. Variations of soil liquefaction safety factors depending on. The vibrations of earthquake shockwaves in watersaturated soils trigger the phenomenon. Feb 12, 2021 factors affecting liquefaction and cyclic mobility. Grain size distribution and soil type earthquake intensity and durationthe most important factor needed to be considered for the hazard of liquefaction is the shaking of the ground due to earthquake or any other type of activities creating such jolts or vibrations in the ground. Soil liquefaction is a major cause of damage during earthquake 1. Estimates of ground motions are primarily a function of rate of earthquake occurrence and rate of attenuation of ground motions away from the epicenter. The excess pore water pressures induced by the seismic action are generated by both a simple stressbased model implemented on a nonlinear.

Seed and idriss 1971 introduced use of a liquefaction triggering curve to relate the cyclic strength of a soil to the normalized standard penetration test spt blow count, which was used as a proxy for the dr and other factors affecting the cyclic strength of the soil. Improved understanding of liquefaction effects on shallow. Most of the boxes are made of high strength aluminium alloy. A method for determining the possibility of liquefaction has also been developed which uses the laboratory test data on large soil samples gupta, 4, gupta 5, gupta 6. The mechanism of liquefaction of soil is very controversial in history. Along with earthquake magnitude, several other factors affect the liquefaction. In the first phase of the study of liquefaction, the cyclic stress ratio approach was applied for all data to analysis of soil liquefaction.

Saturationreadily drained water field capacity water managed by irrigation scheduling minimum balancewater available to plant under stress permanent wilting. Identifying significant influence factors of seismic soil liquefaction. The improved ground behavior is influenced by excess pore water pressure migration, ground motion amplification, inertial force phasing, dynamic component of liquefied soil pressure, presence of a supported structure, and lateral spreading. Apr 18, 2015 liquefaction is a phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking or other rapid loading. Earthquakes are a very common origin of soil liquefaction damage, but other vibrationcreating events can be a factor.

Soil porosity and permeability porosity is the total amount of pore space in the soil 30 to 60% affects the storage of air and water affects the rate of movement of air and water permeability is the ease in which water, air, and plant roots move through the soil ease of air, water and root movement affects rate of water intake and drainage. Two major impacts during shaking are soil liquefaction i. Spt nvalue of sands without significantly affecting shear strength. A more precise definition of soil liquefaction is given by sladen et al. The type of soil most susceptible to liquefaction is one in which the resistance to deformation is mobilized by friction between particles. The destructive effects ofsoil liquefaction were forcibly brought to the attention ofengineers by the disastrous 1964 earthquake in niigata, japan. Thus, the response of soil under the nonundrained conditions can be studied by controlling the ratio of dedti. Poorlygraded sands with rounded particles are more susceptible to liquefaction than wellgraded sands with angular particles. Liquefaction susceptibility of finegrained soils preliminary. Deformations due to cyclic mobility develop incrementally because of static and dynamic stresses that exist during an earthquake. Dec 21, 2014 although traditional methods of liquefaction mitigation have been widely applied in engineering practice, some prominent problems remain such as limits on the size of the treated areas, disturbance of existing structures sensitive to deformation or vibration, and environmental impact. Introduction liquefaction is the phenomenon which is observed when there is loss of strength in saturated and cohesionless soils because of increased pore water. The liquefied soil that is not ejected onto the ground surface redensifies and regains. It shows, both safety factors for the two cases, liquefied and not liquefied, and their percentages, i.

American society for testing materialsstandard test method for relative density of cohesionless soils. Evaluation of liquefaction susceptibility for microzonation. Department of civil engineering, north eastern regional. In common usage, liquefaction refers to the loss of strength in saturated, cohesionless soils due to the buildup of pore water pressures during dynamic loading. Effect of moist tamping water content on the shear strength of soil. Organization of the lecture damages due to liquefaction liquefaction. Ground failure due to earthquakeinduced soil liquefaction may manifest. According to many researchers report and literatures, many factors affect the soil liquefaction. Risk analysis of soil liquefaction in earthquake disasters. Particle cementation, soil fabric, and again are some of the important factors that can hinder soil particle movement. Earthquakeinduced soil liquefaction liquefaction is a leading cause of earthquake damage worldwide. The latter variable has been termed the cyclic stress ratio or the cyclic stress ratio required to generate liq.