Liquefaction Susceptibility of Silty Sands and Low Plastic Clay Soils

2019 ◽  
Vol 10 (2) ◽  
pp. 1-17
Author(s):  
Akhila M. ◽  
Rangaswamy K. ◽  
Sankar N.
Keyword(s):  
Axial Strain ◽  
Clay Fraction ◽  
Fine Sand ◽  
Cyclic Stress ◽  
Clay Soils ◽  
Liquefaction Resistance ◽  
Plastic Clay ◽  
Liquefaction Susceptibility ◽  
Soil Mixtures ◽  
Plastic Clays

The present study evaluates the liquefaction susceptibility of non-plastic silty sands and low plastic clay soils at different cyclic stress levels under undrained triaxial loading conditions. Six different types of soil combinations were prepared after blending the silt and clay fractions into the fine sand. Silty sands contain up to 40% non-plastic fines and low plastic clays comprise 10-20% clay fraction. The cylindrical soil specimens were constituted at the medium relative density and isotropically consolidated at 100 kPa pressure. The consolidated specimens were subjected to cyclic stress amplitudes of 0.127, 0.152 and 0.178 using sinusoidal wave loading at a frequency of 1 Hz. Results were presented in terms of pore pressure build-up and axial strain propagation with load cycles, and liquefaction resistance curves. It was found that the non-plastic silty sands and soil mixtures with plasticity indices up to 15 are more susceptible to liquefaction than the fine sands. The criterion on liquefaction susceptibility of low plastic soil mixtures shows that the soil mixtures with plasticity indices up to 15 containing 20% plastic fines exhibit a sand-like behavior and show higher liquefaction susceptibility than fine sands. It is worthy to note that the low plastic soil mixtures with PI ≥ 10 are more resistant to liquefaction than the silty sands (those contain up to 40% non-plastic fines).

scholarly journals Effect of Plasticity on Liquefaction Susceptibility of Sand-Fines Mixtures

2015 ◽  
Vol 773-774 ◽  
pp. 1407-1411 ◽  
Author(s):  
Aminaton Marto ◽  
Choy Soon Tan ◽  
Ahmad Mahir Makhtar ◽  
Shu Wen Ung ◽  
Mei Yen Lim
Keyword(s):  
Clay Fraction ◽  
Clay Content ◽  
Confining Pressure ◽  
Plasticity Index ◽  
Plastic Limit ◽  
Liquefaction Resistance ◽  
Liquefaction Susceptibility ◽  
Cyclic Behaviour ◽  
Triaxial Apparatus ◽  
Controlling Parameter

The usability of the clay fraction as one of the criteria in the assessment of liquefaction susceptibility is questionable since year 2001. The use of plasticity index to replace clay fraction as a controlling parameter in the criterion is proposed. This paper aims to compare the usability of different parameter in describing the cyclic behaviour of sand-fines mixtures with various plasticity characteristics. The sand-fines mixtures were reconstituted by mixing clean sand with two types of plastic fines at different percentages by weight, at a standardized ratio of 80% of clean sand with 20% of plastic fines. All soil samples were mixed using the dry tamping method to achieve a constant relative density of 20% throughout the specimen. The soil specimens are tested with stress controlled cyclic triaxial apparatus under consolidated undrained condition, with an effective confining pressure of 100kPa. The soil specimens were considered liquefy when the value of pore pressure is equivalent to the initial cell pressure, resulting zeroes effective stress in soil specimen. The results showed that the liquefaction resistance of the sand-fines mixtures increased as the value of plasticity index increased. The plasticity index is a better indicator to describe the liquefaction susceptibility of sand-fines mixtures compare to clay content, plastic limit and activity.

Experimental Study on the Combined Effect of Cyclic and Static Loads on the Mechanical Properties of the Saturated Soft Clay Material

2016 ◽  
Vol 723 ◽  
pp. 843-848
Author(s):  
Yi Wei ◽  
Ying Zhu ◽  
Jing Ni
Keyword(s):  
Mechanical Properties ◽  
Cyclic Load ◽  
Stress Ratio ◽  
Axial Strain ◽  
Soft Clay ◽  
Cyclic Stress ◽  
Excess Pore Pressure ◽  
Static Loads ◽  
Cyclic Stress Ratio ◽  
Excess Pore

The combined effect of cyclic and static loads on the mechanical properties of the soft clay was experimentally investigated by conducting undrained cyclic triaxial tests on Shanghai clay. The results show that an increment in either static or cyclic load increases excess pore pressures and axial strains. For a given value of combined cyclic and static loads, the mechanical properties of the soft clay are more sensitive to the cyclic load. Furthermore, the accumulated excess pore pressure and axial strain for a larger cyclic stress ratio and a lower combined stress ratio might overcome that for a lower cyclic stress ratio and a higher combined stress ratio. The mechanical properties of the soft clay after the cyclic load was unloaded were also discussed. It was observed that the excess pore pressure and axial strain under the static load alone decrease gradually with time. The trend of them largely depends on the ratio of cyclic load to static load.

The implications of reworking on the mineralogy and chemistry of Lower Carboniferous K-bentonites

Clay Minerals ◽  
1996 ◽  
Vol 31 (3) ◽  
pp. 377-390 ◽  
Author(s):  
T. Clayton ◽  
J. E. Francis ◽  
S. J. Hillier ◽  
F. Hodson ◽  
R. A. Saunders ◽  
...  
Keyword(s):  
Trace Element ◽  
Volcanic Ash ◽  
Clay Fraction ◽  
Trace Element Content ◽  
Element Content ◽  
Heavy Minerals ◽  
Lower Carboniferous ◽  
Greenish Yellow ◽  
Trace Element Contents ◽  
Plastic Clays

AbstractPotassium-bentonites have been found in the Courceyan Lower Limestone Shales near Burrington Combe and Oakhill, Somerset, consisting of thin, greenish yellow, plastic clays interbedded within a mudrock and limestone sequence. Mineralogically, the clay fraction is composed of virtually monomineralic interstratified illite-smectite containing 7–10% smectite layers. The clay fraction of the surrounding mudrocks, however, consists of an illite-chlorite dominated assemblage. Their mineral composition, trace element content, and the relative abundance of zircon crystals suggest an origin from burial of montmorillonite originally formed from volcanic ash. The presence of anomalously high trace element contents with both euhedral and rounded zircon grains in the Oakhill K-bentonites suggests a secondary or reworked origin for these samples. In contrast, the presence of a non-anomalous trace element content and large (>100 μm) euhedral zircon grains suggests that the Burrington K-bentonite is primary in origin. Modelling of whole-rock rare-earth element (REE) patterns shows that the Oakhill REE pattern can be derived from the Burrington pattern by the addition of small contributions from zircon and monazite, two major heavy minerals present. These K-bentonites probably represent the oldest Carboniferous K-bentonites so far recorded in the British Isles.

scholarly journals Calcium, magnesium and potassium in mineral soils from the southern half of Finland

1973 ◽  
Vol 45 (3) ◽  
pp. 254-261
Author(s):  
Armi Kaila
Keyword(s):  
Clay Content ◽  
Total Content ◽  
Fine Sand ◽  
Clay Soils ◽  
Surface Layers ◽  
Surface Soils ◽  
Exchangeable Ca ◽  
Heavy Clay ◽  
Southern Half ◽  
Mineral Soils

210 samples of mineral soils from the southern half of Finland with mainly an acid precambrian bedrock, were analysed for the total contents of Ca, Mg and K, and for the portion of these nutrients which could be exchanged by N NH4OAc (pH 7), dissolved by 0.1 N HCI at room temperature, or released by N HCI at 50° C. The total content of Ca was lowest in samples of heavy clay, 0.78±0.14 % in the surface soils and 0.92±0.10 % in the deeper layers. The mean content in the groups of other soils was at least about 1.1 %. The total content of Mg increased with an increase in the clay content (r = 0.81***). It ranged from 0.6±0.1 % in the sand and fine sand samples to 1.53±0.19 % in the heavy clay soils of the surface layers and to 1.89±0.12 % in those of the deeper layers. Also in the groups of loam and silt soils and of the coarser clay soils, respectively, the Mg content was in the deeper layers higher than in the surface soils. The total content of K also increased with the clay content (r=0.73***) from 1.7±0.1 % in the sand and fine sand soils to 2.74±0.21 % in the heavy clay soils of the surface layers and to 3.10±0.07 % in those of the deeper layers. The portion of exchangeable Ca was relatively high: in the groups of surface soils from more than one tenth to one third of the total amount. The corresponding average amounts released by even the more drastic treatment with acid were not markedly higher. Only a few per cents of total Mg were exchangeable and slightly higher amounts were dissolved by 0.1 N HCI, whereas the treatment with N HCI at 50° C released about half of the total Mg. Exchangeable K and K dissolved by 0,1 N HCI did not exceed 1 % of the total K, except slightly in the heavy clay soils; the average amounts released by N HCI ranged from 5 to 18 % of the total K. The plant availability of these nutrients was discussed.

scholarly journals Effect of Variable Confining Pressure on Cyclic Triaxial Behavior of K0-consolidated Soft Marine Clay

2018 ◽  
Vol 4 (4) ◽  
pp. 755
Author(s):  
Lei Sun
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Confining Pressure ◽  
Stress Path ◽  
Cyclic Stress ◽  
Marine Clay ◽  
Stress Ratios ◽  
Variable Confining Pressure

The effect of variable confining pressure (VCP) on the cyclic deformation and cyclic pore water pressure in K0-consolidated saturated soft marine clay were investigated with the help of the cyclic stress-controlled advanced dynamic triaxial test in undrained condition. The testing program encompassed three cyclic deviator stress ratios, CSR=0.189, 0.284 and 0.379 and three stress path inclinations ηampl=3,1 and 0.64. All tests with constant confining pressure (CCP) and variable confining pressure (VCP) have identical initial stress and average stress. The results were analyzed in terms of the accumulative normalized excess pore water pressure rqu recorded at the end of each stress cycle and permanent axial strain, as well as resilient modulus. Limited data suggest that these behavior are significantly affected by both of the VCP and CSR. For a given value of VCP, both of the pore water pressure rqu and permanent axial strains are consistently increase with the increasing values of CSR. However, for a given value of CSR, the extent of the influence of VCP and the trend is substantially depend on the CSR.

scholarly journals The effect of confinement in liquefaction tests carried out in a cyclic simple shear apparatus

2019 ◽  
Vol 92 ◽  
pp. 08002 ◽  
Author(s):  
Lucia Mele ◽  
Stefania Lirer ◽  
Alessandro Flora
Keyword(s):  
Simple Shear ◽  
Initial Conditions ◽  
Confining Pressure ◽  
Cyclic Stress ◽  
Shear Tests ◽  
Liquefaction Resistance ◽  
Pressurized Water ◽  
Cyclic Stress Ratio ◽  
Complex Behaviour ◽  
Continuous Rotation

The cyclic simple shear tests can be used to reproduce in laboratory the complex behaviour of the soil during an earthquake, simulating the continuous rotation of the principal stress axes. In this research a comparison of results between cyclic simple shear tests carried out with confining pressure or confining rings is reported. A cyclic simple shear apparatus is used to carry out tests with confining rings (the conventional way to carry out cyclic simple shear tests) and with a confining pressure applied to the specimen through pressurized water, where the K0 condition during consolidation is guaranteed by a sophisticated control system. The apparatus, in both the configurations, is described in detail. All tests were carried out on reconstituted specimens of an Italian sand with similar initial conditions, such as low relative density and confining pressure. All experimental results are reported in the plane cyclic stress ratio (CSR) and number of cycles where liquefaction occurs (Nliq) in order to evaluate the effect of confinement on the liquefaction resistance of the studied sand.

scholarly journals Characterization, agricultural potential, and perspectives for the management of light soils in Brazil

2016 ◽  
Vol 51 (9) ◽  
pp. 1003-1020 ◽  
Author(s):  
Guilherme Kangussu Donagemma ◽  
Pedro Luiz de Freitas ◽  
Fabiano de Carvalho Balieiro ◽  
Ademir Fontana ◽  
Silvio Túlio Spera ◽  
...  
Keyword(s):  
Cover Crops ◽  
Production Systems ◽  
Sandy Loam ◽  
Soil Depth ◽  
Clay Fraction ◽  
Fine Sand ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Agricultural Frontier ◽  
Agricultural Potential

Abstract Light soils occupy 8% of the Brazilian territory and are especially expressive in the new and last agricultural frontier in Brazil: the Matopiba region - in the states of Maranhão, Tocantins, Piauí, and Bahia -, where they represent 20% of the area. These soils fit into the textural classes of sand and loamy sand or sandy loam, down to 0.75-m soil depth or deeper, and they are mainly represented by Neossolos Quartzarênicos (Quartzipsamments) and, partly, by Latossolos (Oxisols) and Argissolos (Ultisols). The understanding of soil functioning depends on the establishment of distinguishing criteria for: organic matter dynamics; content and mineralogy of the clay fraction; coarse sand and total sand contents, in relation to those of fine sand; mean diameter of the sand fraction; and water retention capacity. These criteria can contribute for the zoning and for the conservation and fertility management of light soils, as well as for the estimation of their agricultural potential. Integrated production systems, such as crop-livestock and crop-livestock-forestry integration, besides no-tillage with crop rotation, mixed forestry planting with legumes, and the use of green manure and cover crops are relevant for the proper management of these soils. The objective of this review was to characterize light soils and to highlight the main challenges regarding their agricultural potential and their conservation and fertility managements, in face of the expansion and consolidation of the new Brazilian agricultural frontier.

Apparatus for strain and load cycling at elevated temperature with high-accuracy control during hold periods

1970 ◽  
Vol 5 (4) ◽  
pp. 284-291 ◽  
Author(s):  
D J White ◽  
G P Horwood ◽  
Z Czajkowski
Keyword(s):  
Load Capacity ◽  
Axial Strain ◽  
Testing Machine ◽  
Cyclic Stress ◽  
Hydraulic Testing ◽  
Gauge Length ◽  
Conic Section ◽  
Accuracy Control ◽  
Load Cycling ◽  
Better Than

A description is given of apparatus which has been developed to determine accurately the cyclic stress-strain behaviour of materials subjected to combined high-strain fatigue and creep at temperatures up to 700°C. The servo-hydraulic testing machine has a load capacity of ±20 000 lbf in push-pull and can operate in either a strain-cycling or a load-cycling mode. The specimen has a diameter of 0.5 in and a parallel gauge length of 1.5 in terminating in conic-section ridges on which extensometers are mounted for the measurement and control of axial strain. Strain is held constant to better than ±1 × 10−5 during hold times of up to 12 h and temperature control is better than ±0.5 degC.

Study of Variation of Soil Stress State Based on the Curve of Normalized Strain- Pore Water Pressure

2013 ◽  
Vol 275-277 ◽  
pp. 295-298
Author(s):  
Gang Yang ◽  
Qing Yang ◽  
Wen Hua Liu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Cyclic Stress ◽  
Cyclic Stress Ratio ◽  
Cycle Number ◽  
Soil Stress ◽  
Critical Cyclic Stress Ratio ◽  
Versus Strain

The cyclic behavior of normally consolidated silty clays was investigated by conducting a series of cyclic simple shear tests on one-dimensionally and isotropically consolidated reconstituted samples. The critical cyclic stress ratio was obtained by the normalized axial strain. Based on hysteretic curve of pore water pressure versus strain, dynamic characteristics of silty clay were investigated. The results showed that with increasing of cyclic loading, soil stress state can be divided into steady state, critical state and failure state based on the critical cyclic stress ratio. The hysteresis curve of pore water pressure versus strain was divided into two parts by cross point A. Compared with two parts, the variation law was obtained. When the upper part area was bigger than the lower part area, pore water pressure and axial strain continuously increase with cycle number; when the upper part area was smaller than the lower part area, pore water pressure and axial strain tended to be steady with cycle number.

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