11. Effect of saturation on liquefaction resistance of iron ore fines and two sandy soils

Prévia do material em texto

<p>H O S T E D B Y The Japanese Geotechnical Society</p><p>Soils and Foundations</p><p>Soils and Foundations 2016;56(4):732–744</p><p>http://d</p><p>0038-0</p><p>(http://c</p><p>nCor</p><p>E-m</p><p>Peer</p><p>x.doi.org/1</p><p>806/& 201</p><p>reativecom</p><p>respondin</p><p>ail addre</p><p>review un</p><p>www.sciencedirect.com</p><p>journal homepage: www.elsevier.com/locate/sandf</p><p>Technical Paper</p><p>Effect of saturation on liquefaction resistance of iron ore fines</p><p>and two sandy soils</p><p>Hailong Wanga,n, Junichi Kosekib, Takeshi Satoc, Gabriele Chiarod, Jaylord Tan Tianb</p><p>aOYO Corporation, Formerly Research fellow of Institute of Industrial Science, The University of Tokyo, Japan</p><p>bDepartment of Civil Engineering, The University of Tokyo, Japan</p><p>cIntegrated Geotechnology Institute Ltd., Japan</p><p>dDepartment of Civil and Natural Resources Engineering, University of Canterbury, Christchurch, New Zealand</p><p>Received 19 April 2015; received in revised form 3 March 2016; accepted 20 May 2016</p><p>Available online 18 August 2016</p><p>Abstract</p><p>Over the past several years, the International Maritime Organization (IMO) has become increasingly concerned about the liquefaction of</p><p>unsaturated solid bulk cargo (e.g. iron ore fines) during maritime transportation. This concern has arisen due to several accidents including the</p><p>capsizing of vessels. In addition, although the resistance against liquefaction of ordinary unsaturated soils is higher than for saturated soils,</p><p>possible key parameters governing the liquefaction resistance of unsaturated soils (RL,unsat) have not yet been clearly identified. Therefore, in this</p><p>study, undrained cyclic loading tests of saturated and unsaturated iron ore fines and two sandy soils were conducted using a triaxial apparatus to</p><p>reveal the liquefaction behavior of iron ore fines and to find the key parameters governing RL,unsat. Through comparisons, it was found that the</p><p>liquefaction behavior of iron ore fines is similar to that of sandy soils. The degree of saturation and potential volumetric strain, which have been</p><p>proposed as the governing parameters of RL,unsat, were examined based on experimental data obtained in this study and by other researchers. It</p><p>was shown that neither of the two parameters correlate with the liquefaction resistance ratio (LRR), a ratio of RL,unsat to the liquefaction resistance</p><p>of the saturated soils (RL,sat) with a unique relationship, especially when considering soils with considerable fines content. Following the concept</p><p>of potential volumetric strain, which considers the compressibility of pore air in the unsaturated soils, volumetric expansion due to the reduction</p><p>in confining pressure during cyclic loading is further considered, and a new index, the volumetric strain ratio (Rv) is proposed in this study.</p><p>According to the experimental data obtained in this study, Rv exhibits a much better correlation with LRR than the two former parameters.</p><p>& 2016 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND</p><p>license (http://creativecommons.org/licenses/by-nc-nd/4.0/).</p><p>Keywords: Iron ore fines; Unsaturated soils; Liquefaction; Volumetric strain ratio; Triaxial test</p><p>1. Introduction</p><p>Awareness was recently raised among the International</p><p>Maritime Organization (IMO) due to the substantial losses</p><p>caused reportedly by liquefaction of solid bulk cargo e.g. iron</p><p>ore fines, nickel ore, sinter feed bauxite etc. during maritime</p><p>0.1016/j.sandf.2016.07.013</p><p>6 The Japanese Geotechnical Society. Production and hosting by</p><p>mons.org/licenses/by-nc-nd/4.0/).</p><p>g author.</p><p>ss: whlxy2002@gmail.com (H. Wang).</p><p>der responsibility of The Japanese Geotechnical Society.</p><p>transportation (Isacson, 2010a, b; LPC, 2011; Gard, 2012 etc.).</p><p>Though such solid bulk cargo is usually loaded into the vessels</p><p>under the unsaturated condition, the capsizing of vessels due to</p><p>the liquefaction of such cargo subjected to ocean wave motion,</p><p>for example, cannot be prevented in some cases due to a lack</p><p>of knowledge about the liquefaction of these materials.</p><p>In addition, in earthquake-prone countries, such as Japan,</p><p>the liquefaction resistance of unsaturated soils is a much-</p><p>researched topic in the field of geotechnical engineering. A</p><p>great number of liquefaction sites were reported in the Tohoku</p><p>Elsevier B.V. This is an open access article under the CC BY-NC-ND license</p><p>http://crossmark.crossref.org/dialog/?doi=10.1016/j.sandf.2016.07.013&domain=pdf</p><p>http://www.sciencedirect.com</p><p>www.elsevier.com/locate/sandf</p><p>http://dx.doi.org/10.1016/j.sandf.2016.07.013</p><p>http://dx.doi.org/10.1016/j.sandf.2016.07.013</p><p>http://dx.doi.org/10.1016/j.sandf.2016.07.013</p><p>mailto:whlxy2002@gmail.com</p><p>http://dx.doi.org/10.1016/j.sandf.2016.07.013</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>Nomenclature</p><p>CSR cyclic stress ratio (¼qcyclic/2s00)</p><p>Dc compaction degree before applying cyclic loading</p><p>Dr relative density before applying cyclic loading</p><p>e void ratio</p><p>emax maximum void ratio</p><p>emin minimum void ratio</p><p>DA¼5% 5% double amplitude of axial strain</p><p>DA¼5% criterion criterion for liquefaction based on the</p><p>condition of DA¼5%</p><p>Fc fines content</p><p>Gs specific gravity</p><p>IMO International Maritime Organization</p><p>LRR liquefaction resistance ratio, a ratio of RL,unsat to</p><p>RL,sat</p><p>LRRDA¼5% LRR, in which RL is determined based on</p><p>DA¼5% criterion</p><p>LRRΔu¼0.9s00 LRR, in which RL is determined based on</p><p>Δu¼0.9s00 criterion</p><p>NDA¼5% number of cycles to trigger liquefaction based on</p><p>DA¼5% criterion</p><p>NΔu¼0.9s00 number of cycles to trigger liquefaction based</p><p>on Δu¼0.9s00 criterion</p><p>p total mean principal stress</p><p>p-constant condition a condition to maintain p constant</p><p>during applying vertical cyclic loading</p><p>p�ua net mean principal stress of unsaturated soil</p><p>p�uw effective mean principal stress of unsaturated soil</p><p>p�u effective mean principal stress denoting either</p><p>p�ua or p�uw</p><p>qcyclic single amplitude of vertical cyclic stress</p><p>RL resistance against liquefaction</p><p>RL,sat RL of the saturated soil</p><p>RL,unsat RL of the unsaturated soil</p><p>Rv volumetric strain ratio (¼εν,air/εν,s0)</p><p>S matric suction (¼ ua�uw)</p><p>Sr degree of saturation</p><p>ua pore air pressure</p><p>uw pore water pressure</p><p>wopt optimum water content</p><p>Δu excess pore pressure, denoting either Δua or Δuw</p><p>Δua excess pore air pressure</p><p>Δuw excess pore water pressure</p><p>Δu¼0.9s00 a condition when Δu equals 90% s00</p><p>Δu¼0.9s00 criterion criterion for liquefaction based on the</p><p>condition of Δu¼0.9s00</p><p>εν,air volumetric strain caused by pore air compression</p><p>εν,0.9air volumetric strain caused by pore air compression</p><p>when Δua¼0.9s00</p><p>ε*ν,air potential volumetric strain, namely, εν,air when</p><p>Δua¼s00</p><p>εν,s0 volumetric strain caused by reduction of s0</p><p>εν,0.9s0 εν,s0 due to reduction of s0 by 90%</p><p>εν,τ volumetric strain caused by contraction (or nega-</p><p>tive dilatancy)</p><p>ρdmax maximum dry density obtained from</p><p>compaction test</p><p>s0 confining pressure</p><p>s00 initial confining pressure</p><p>sh cell pressure</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744 733</p><p>district (Yamaguchi et al., 2012) and the Kanto district,</p><p>including the Tokyo Bay area (Yasuda et al., 2012; Towhata</p><p>et al., 2014) after the Great East Japan Earthquake Disaster in</p><p>2011. Severe damage to houses (e.g. tilting, cracking etc.),</p><p>roads and lifeline facilities was incurred in the liquefaction</p><p>affected areas. As a possible countermeasure against liquefac-</p><p>tion, which can be applied to the narrowly constructed</p><p>residential areas, ground desaturation by either dewatering</p><p>the ground or the injection of micro air bubbles has been given</p><p>particular attention in recent years due to its low cost</p><p>(Okamura et al., 2006; NILIM, 2011, 2013).</p><p>To the authors' knowledge, starting from the early work by</p><p>Sherif et al. (1977), it has been repeatedly shown that soils</p><p>under the unsaturated condition show higher resistance against</p><p>liquefaction than those under the saturated condition. How-</p><p>ever, the governing parameters determining the liquefaction</p><p>resistance of unsaturated soils remain unclear. Attempts were</p><p>made to determine the role played by the degree of saturation</p><p>Sr (Yoshimi et al., 1989; Goto and Shamoto, 2002), pore-</p><p>pressure</p><p>coefficient B value (Yoshimi et al., 1989; Unno et al.,</p><p>2008; Arab et al., 2011), elastic wave velocity (Huang et al.,</p><p>1999; Ishihara et al., 2001; Tsukamoto et al., 2002; Yang,</p><p>2002; Yang et al., 2004) and potential volumetric strain</p><p>(Okamura and Soga, 2006). It seems that the first three</p><p>parameters can work well only for a given soil under similar</p><p>test conditions, and the last parameter needs to be verified on</p><p>soils with considerable fines content.</p><p>In this study, undrained cyclic loading tests were conducted</p><p>on one type of iron ore fines and two types of sandy soils by</p><p>employing a stress-controlled triaxial apparatus. The liquefac-</p><p>tion behaviors of iron ore fines were compared with those of</p><p>ordinary sandy soils. Based on the test data obtained in this</p><p>study and that reported in the literature, two parameters</p><p>proposed to be the governing factors of liquefaction resistance</p><p>of the unsaturated soil are discussed. Finally, following</p><p>relevant findings from past studies, a new governing index is</p><p>proposed.</p><p>2. Apparatus</p><p>Both saturated and unsaturated specimens were tested on the</p><p>same apparatus, while extra components were added to the</p><p>apparatus for the unsaturated tests as schematically illustrated</p><p>in Fig. 1. Sinusoidal vertical cyclic loading with frequency of</p><p>0.1 Hz is applied by a double action cylinder controlled by a</p><p>function generator and an E/P regulator. There is another set of</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>Fig. 1. Layout of the apparatus employed for undrained cyclic loading tests on unsaturated specimens.</p><p>Fig. 2. Particle size distribution of tested soils.</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744734</p><p>function generator and E/P regulator to control the cell</p><p>pressure (sh) in order to maintain the total mean principal</p><p>stress (p) constant (i.e. p-constant condition: Huang et al.,</p><p>1999; and Tsukamoto et al., 2002). By introducing the</p><p>membrane filter technique (Nishimura et al., 2012; Wang</p><p>et al., 2014) to the pedestal instead of the traditional ceramic</p><p>disk for unsaturated specimens, the test duration can be</p><p>reduced and the pore water (uw) can be measured promptly</p><p>by the connected pressure transducer. The pore air pressure</p><p>(ua) is measured by another pressure transducer connected to</p><p>the top cap, on which a hydrophobic filter is glued. Volume</p><p>change of the unsaturated specimens is monitored by the inner</p><p>cell system. A detailed description of the apparatus can be</p><p>found in Wang et al. (2015).</p><p>3. Testing programs</p><p>As testing materials, Iron ore fines type B (IOF-B), Toyoura</p><p>sand and Inagi sand were used. Their gradation curves are</p><p>shown in Fig. 2. Iron ore fines (IOF) is tentatively defined by</p><p>the IMO as iron ore containing 10% or more particles less than</p><p>1 mm and 50% or more particles less than 10 mm (IMO,</p><p>2013). IOF-B (fines content Fc¼24%) used in this study and</p><p>Inagi sand (Fc¼30%) can be classified as non-plastic sands.</p><p>Their specific gravity (Gs), maximum dry density (ρdmax) and</p><p>optimum water content (wopt) are 4.444, 2.79 g/cm3 and 12%</p><p>for IOF-B, and 2.656, 1.66 g/cm3 and 20% for Inagi sand,</p><p>respectively (the compaction tests were conducted following</p><p>the method A of JIS A 1210 with the similar compaction</p><p>energy to the standard Proctor method, where JIS stands for</p><p>the Japanese Industrial Standard). On the other hand, Toyoura</p><p>sand is a clean sand with negligible fines content (Fco0.5%).</p><p>Its maximum void ratio (emax), minimum void ratio (emin) and</p><p>Gs are 0.989, 0.611 and 2.652, respectively (emax and emin were</p><p>measured based on JIS A 1224).</p><p>All the specimens were 50 mm in diameter and 100 mm in</p><p>height. The undrained cyclic loading test conditions are</p><p>described in Table 1. The specimens of IOF-B and Inagi sand</p><p>were molded by one-dimensional compression with an initial</p><p>water content of 12% and 22%, respectively. The double</p><p>vacuum method (Ampadu and Tatsuoka, 1993) was applied to</p><p>saturate the specimens. The unsaturated specimens of IOF-B</p><p>with Dc of 93%, s00 of 100 kPa and Sr of 72% were tested by</p><p>keeping the initial water content (12%) and all the other</p><p>unsaturated specimens of IOF-B were flushed by distilled</p><p>water (without de-airing) prior to the cyclic loading. For the</p><p>unsaturated specimens of Inagi sand, a pre-determined amount</p><p>of water was added from the top of the specimens to obtain the</p><p>desired Sr and curing of the specimens was undertaken for</p><p>approximately 10 h in the mold in order to achieve a uniform</p><p>water distribution in the specimens. Medium dense specimens</p><p>(Dr: 56–68%) of Toyoura sand were made by the air pluviation</p><p>method for the saturated specimens, while the moisture</p><p>tamping method was used for the unsaturated specimens to</p><p>prevent the dry sand from absorbing water from the membrane</p><p>filter fixed on the pedestal, which would result in difficulty</p><p>taking uw measurements. The effect of specimen preparation</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>Table 1</p><p>Conditions of undrained cyclic loading tests.</p><p>Types of</p><p>soils</p><p>Density s00 (kPa) Sr (%) RL (DA¼5%) RL (u¼0.9s00)</p><p>IOF-B Dc: 93%</p><p>(91�94%)</p><p>100 100a 0.315 0.315</p><p>84 0.475 0.508</p><p>72b 0.546 –</p><p>50 100a 0.334 0.324</p><p>81 0.532 0.579</p><p>Dc: 87%</p><p>(87�88%)</p><p>100 100a 0.228 0.228</p><p>85 0.400 0.408</p><p>Dc: 81%</p><p>(75�84%)</p><p>100 100a 0.121 0.118</p><p>76 0.201 0.204</p><p>50 100a 0.120 0.120</p><p>71 0.200 0.201</p><p>Inagi sand Dc: 76%</p><p>(73�77%)</p><p>60 100a 0.140 0.140</p><p>84 0.189 0.189</p><p>73b 0.266 0.273</p><p>68a,b 0.250 0.255</p><p>Toyoura</p><p>sand</p><p>Dr: 63%</p><p>(56�68%)</p><p>60 100a 0.160 0.160</p><p>92 0.351 0.351</p><p>Dr: �4%</p><p>(-2�-12%)</p><p>60 100a 0.079 0.079</p><p>79 0.221 0.223</p><p>Notes: Dr and Dc: average values and ranges (in parentheses) of relative density and compaction degree before applying cyclic loading (Dc¼ρdtest/ρdmax� 100,</p><p>ρdtest: dry density of the tested specimens); s00 and Sr: initial confining pressure and degree of saturation before applying cyclic loading; RL (DA¼5%) and RL</p><p>(u¼0.9s00): liquefaction resistance defined by DA¼5% and u¼0.9s00 criteria.</p><p>aThe tests were conducted without the p-constant condition.</p><p>bSuction of these specimens was measured before and during cyclic loading (the suction values for Inagi sand and IOF-B specimens were about 4 kPa and 1 kPa,</p><p>respectively before applying cyclic loading).</p><p>Fig. 3. Typical pore water, pore air and suction measurements on (a) Inagi sand and (b) Iron ore fines.</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744 735</p><p>methods on the resistance against liquefaction is discussed in a</p><p>later section. The extremely loose specimens (Dr:</p><p>�2��12%) of Toyoura sand were all made by moisture</p><p>tamping following the instructions provided by Ishihara</p><p>(1993). The specimens of Toyoura sand were either flushed</p><p>by CO2 and de-aired water followed by applying back pressure</p><p>of 200 kPa to achieve the saturated condition (B value</p><p>Z0.95), or only flushed by distilled water (without de-airing)</p><p>to remain in the unsaturated condition. In addition, the volume</p><p>change of extremely loose Toyoura sand specimens caused by</p><p>the saturation or water flushing processes was taken into</p><p>account in the interpretation of the test results.</p><p>The cell pressure (sh) condition during the application of</p><p>vertical cyclic loading was kept constant (without the p-constant</p><p>Fig. 4. Typical behaviors of saturated IOF-B specimens with Dc of 93%</p><p>(a) stress strain relationship and (b) effective stress path.</p><p>Fig. 5. Typical behaviors of saturated IOF-B specimens with Dc of 87%</p><p>(a) stress strain relationship and (b) effective stress path.</p><p>Fig. 6. Typical behaviors of saturated IOF-B specimens with Dc of 81%</p><p>(a) stress strain relationship and (b) effective stress path.</p><p>Fig. 7. Typical behaviors of saturated Inagi sand specimens (a) stress strain</p><p>relationship and (b) effective stress path.</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744736</p><p>condition) for all the saturated specimens and regulated to keep</p><p>the p-constant condition for most of the unsaturated specimens.</p><p>In addition, the sh of the specimens of Inagi sand with Sr of</p><p>68% was kept constant for comparison purposes.</p><p>4. Test results</p><p>The apparatus</p><p>performed well when measuring the suction</p><p>(S¼ua�uw) of unsaturated specimens, as described in detail</p><p>by Wang et al. (2015). With some unsaturated Inagi sand and</p><p>IOF-B specimens, relatively low suction values were mea-</p><p>sured, as indicated in Table 1, and the typical measurement</p><p>results during cyclic loading are shown in Fig. 3. On the other</p><p>hand, for specimens for which no suction measurements were</p><p>taken due to their relatively high Sr values, it would be</p><p>appropriate to assume their suction values were nearly zero.</p><p>The effect of suction on the cyclic behaviors of soils is not</p><p>discussed in this paper. It is sufficient to note that the term</p><p>muril</p><p>Realce</p><p>Fig. 8. Typical behaviors of saturated medium dense specimens of Toyoura</p><p>sand (a) stress strain relationship and (b) effective stress path.</p><p>Fig. 9. Typical behaviors of saturated extremely loose specimens of Toyoura</p><p>sand (a) stress strain relationship and (b) effective stress path.</p><p>Fig. 10. Typical behaviors of unsaturated IOF-B specimens with Dc of 93%</p><p>(a) stress strain relationship and (b) effective stress path.</p><p>Fig. 11. Typical behaviors of unsaturated IOF-B specimens with Dc of 87%</p><p>(a) stress strain relationship and (b) effective stress path.</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744 737</p><p>p�u is used to represent the effective stress state of the</p><p>specimens, where u¼ua for specimens with suction measure-</p><p>ments and u¼uw for specimens without suction measurements.</p><p>4.1. Effective stress paths and stress strain relationships</p><p>4.1.1. Saturated specimens</p><p>Figs. 4–6 show the typical cyclic stress strain relationships</p><p>and effective stress paths of saturated IOF-B specimens with</p><p>Dc of 93%, 87% and 81% under s00 of 100 kPa, respectively.</p><p>For the sake of comparison, Figs. 7–9 report the cyclic</p><p>behaviors of saturated specimens of Inagi sand and Toyoura</p><p>sand (medium dense and extremely loose conditions),</p><p>respectively.</p><p>For saturated IOF-B, zero effective stress is reached regard-</p><p>less of density. It is also observed that the assigned deviator</p><p>stress amplitude (qcyclic) cannot be achieved for relatively loose</p><p>IOF-B (e.g. Dc¼81% in Fig. 6) at large axial strain amplitude</p><p>after the effective stress reaches zero, while qcyclic is reached at</p><p>limited strain for the relatively dense specimen (i.e. Dc¼93%</p><p>muril</p><p>Realce</p><p>Fig. 12. Typical behaviors of unsaturated IOF-B specimens with Dc of 81%</p><p>(a) stress strain relationship and (b) effective stress path.</p><p>Fig. 13. Typical behaviors of unsaturated Inagi sand specimens (a) stress strain</p><p>relationship and (b) effective stress path.</p><p>Fig. 14. Typical behaviors of unsaturated medium dense specimens of</p><p>Toyoura sand (a) stress strain relationship and (b) effective stress path.</p><p>Fig. 15. Typical behaviors of unsaturated extremely loose specimens of</p><p>Toyoura sand (a) stress strain relationship and (b) effective stress path.</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744738</p><p>in Fig. 4). As can be seen in Figs. 8 and 9, similar behavior</p><p>was also observed for ordinary Toyoura sand: once zero</p><p>effective stress is achieved, the cyclic mobility behavior</p><p>changes to a flow type liquefaction behavior as the densities</p><p>of the specimens decrease from a medium dense to an</p><p>extremely loose condition.</p><p>4.1.2. Unsaturated specimens</p><p>Figs. 10–12 show the typical cyclic stress strain relation-</p><p>ships and effective stress paths of unsaturated IOF-B</p><p>specimens with a Dc of 93%, 87% and 81%, respectively.</p><p>Figs. 13–15 illustrate similar relationships for unsaturated</p><p>Inagi sand and Toyoura sand (medium dense and extremely</p><p>loose), respectively.</p><p>While much larger cyclic stress loading amplitudes than</p><p>those applied on the corresponding saturated specimens were</p><p>applied on the unsaturated specimens in order to trigger</p><p>liquefaction, not all the unsaturated specimens reach a zero</p><p>effective stress state before the end of the tests (e.g. IOF-B in</p><p>Figs. 10 and 11, Inagi sand in Fig. 13). It is worth mentioning</p><p>that brittle failure at the extension side accompanied by large</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>Fig. 16. Relationship between CSR and the number of cycles for Toyoura sand specimens (a) medium dense condition and (b) extremely loose condition.</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744 739</p><p>vertical deformation was observed for IOF-B specimens with a</p><p>Dc of 93% and 87%.</p><p>From the stress stain relationships, it can be seen that most</p><p>of axial strain of unsaturated IOF-B with Dc of 93% (Fig. 10)</p><p>and medium dense Toyoura sand specimen (Fig. 14) accumu-</p><p>lated in the extension side (i.e. negative strain). On the other</p><p>hand, the accumulated strain is rather symmetric in the</p><p>compression (i.e. positive strain) and extension sides for</p><p>IOF-B with Dc of 81% and Inagi sand (Figs. 12 and 13).</p><p>For unsaturated specimens with a relatively loose condition</p><p>(IOF-B specimens with a Dc of 81%, Inagi sand specimens and</p><p>extremely loose Toyoura sand specimens in Figs. 12, 13 and</p><p>15, respectively), one of the primary characteristics is that the</p><p>cyclic mobility behavior (Seed, 1979) is observed clearly,</p><p>while for the corresponding saturated specimens, the behavior</p><p>resembles flow type liquefaction at the late stage of the tests</p><p>(Figs. 6, 7 and 9).</p><p>4.1.3. Liquefaction resistance</p><p>The relationship between the cyclic stress ratio (CSR ¼</p><p>qcyc/2s00) applied to the specimens and the number of cycles</p><p>required to induce liquefaction is discussed in this section.</p><p>Liquefaction is defined by either a 5% double amplitude of</p><p>axial strain (DA¼5% criterion) or by the development of the</p><p>excess pore water pressure (or excess pore air pressure for the</p><p>specimens with positive suction measurement) to 90% the</p><p>initial confining pressure (Δu ¼ 0.9 s00 criterion) for both</p><p>saturated and unsaturated specimens. Though neither of these</p><p>definitions guarantees that the tested materials reach the state</p><p>of liquefaction defined by Castro (1975) and Castro and Poulos</p><p>(1977), they can be conveniently applied to the widely</p><p>accepted framework proposed by Seed and Idriss (1971) and</p><p>Seed (1979) to evaluate the resistance against liquefaction (RL)</p><p>of the soil. Note that the relationship between CSR and the</p><p>number of cycles before Δu ¼ 0.9 s00 changes when</p><p>considering the effect of suction on the effective stress</p><p>variables (e.g. s00). This issue will be discussed later in the</p><p>context of the results of unsaturated Inagi sand specimens.</p><p>Fig. 16(a) and (b) shows the relationship between CSR and</p><p>the number of cycles (i.e. NDA¼5%, DA¼5% criterion in solid</p><p>points and NΔu¼0.9s00, Δu ¼ 0.9s00 criterion in open points)</p><p>for Toyoura sand specimens with medium dense (Dr¼63%)</p><p>and extremely loose conditions (Dr¼�4%), respectively. It</p><p>can be seen that NDA¼5% and NΔu¼0.9s00 of each test are</p><p>similar except in the case of medium dense specimens</p><p>subjected to relatively large CSR. The liquefaction resistance</p><p>curves are parallel for the saturated and unsaturated cases</p><p>under otherwise similar conditions. The liquefaction resistance</p><p>of saturated soils (RL,sat) is defined here as the corresponding</p><p>CSR value on the liquefaction resistance curve that results in</p><p>either DA¼5% or Δu¼0.9s00 after 20 cycles of loading. The</p><p>same definition is applied to the liquefaction resistance of the</p><p>unsaturated specimens (RL,unsat). Clearly, RL,unsat is much</p><p>higher than RL,sat for Toyoura sand specimens prepared at</p><p>the similar density conditions. As was mentioned, Toyoura</p><p>sand specimens with medium dense (Dr¼63%) were prepared</p><p>by the air pluviation method for the saturated case and the</p><p>moisture tamping method for the unsaturated case. Tatsuoka et</p><p>al. (1986) reported that for Toyoura sand specimens with a Dr</p><p>of 60%, the RL,sat of specimens prepared by air pluviation</p><p>method was 69% that of specimens prepared by moisture</p><p>tamping method. The solid star symbol in Fig. 16(a) shows the</p><p>position of 69% of RL,unsat of the test results obtained in this</p><p>study. On the other hand, Huang et al. (1999) reported on the</p><p>RL of saturated and unsaturated Toyoura sand specimens with</p><p>a Dr of 60% prepared by air pluviation</p><p>method as shown in</p><p>Fig. 16(a). Though the significant effect of the preparation</p><p>method on RL,sat has also been reported by some other</p><p>researchers (Mulilis et al., 1977; Sze and Yang, 2014), it can</p><p>be seen from Fig. 16(a) that the significance may be less in the</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>Fig. 17. Relationship between CSR and the number of cycles for Inagi sand specimens (a) saturated specimens and unsaturated specimens with the p-constant</p><p>condition, (b) unsaturated specimens with/without the p-constant condition and (c) unsaturated specimens with different definitions of effective stress variables.</p><p>Fig. 18. Relationship between CSR and the number of cycles for the saturated</p><p>IOF-B specimens with different density conditions.</p><p>Fig. 19. Relationship between CSR and the number of cycles for the IOF-B</p><p>specimens with Dc of 93%.</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744740</p><p>case of unsaturated specimens. Therefore, the effect of the</p><p>specimen preparation method is not considered in the</p><p>discussion.</p><p>Fig. 17(a) shows the relationship between the CSR and the</p><p>number of loading cycles for saturated Inagi sand specimens</p><p>and unsaturated Inagi sand specimens with the p-constant</p><p>condition. The NDA¼5% and NΔu¼0.9s00 for each saturated</p><p>specimen are similar, while it seems that the development of</p><p>DA¼5% takes place earlier than Δu¼0.9s00 as Sr decreases.</p><p>Also in the case of Inagi sand, RL,unsat is larger than RL,sat. Fig.</p><p>17(b) compares the results between the unsaturated specimens</p><p>with and without the p-constant conditions. It implies that the</p><p>liquefaction resistance under the p-constant condition</p><p>(Sr¼73%) is slightly higher than that without the p-constant</p><p>condition (Sr¼68%). This may be attributed to the total stress</p><p>path and the current cyclic stress ratios (Koseki et al., 2005) of</p><p>the two test conditions. Details on this issue will be presented</p><p>elsewhere. The liquefaction resistance curve of unsaturated</p><p>Inagi sand is shown in Fig. 17(c). The curve is obtained by</p><p>using the state variables s0 ¼p�ua, and s0 ¼ (p�ua)þχ</p><p>(ua�uw) defined by Vanapalli et al. (1996), and the residual</p><p>degree of saturation (Sr0¼58%) was obtained by Wang et al.</p><p>(2015). It can be seen that the difference caused by the</p><p>different definitions of state variables is very small. In this</p><p>study, as stated before, the effect of suction is not considered.</p><p>It is acknowledged, however, that the effect of suction should</p><p>be further studied.</p><p>Fig. 18 shows the CSR versus the number of cycles of</p><p>saturated IOF-B specimens under different density and con-</p><p>fining pressure conditions. It can be seen that RL,sat values</p><p>increase as the density increases, while the confining pressure</p><p>seems to have a negligible or a minor effect on RL,sat in the</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>Fig. 20. Relationship between CSR and the number of cycles for the IOF-B</p><p>specimens with Dc of 87%.</p><p>Fig. 21. Relationship between CSR and the number of cycles for the IOF-B</p><p>specimens with Dc of 81%.</p><p>Fig. 22. Relationship between Sr and liquefaction resistance ratio defined by</p><p>DA¼5% criterion (LRRDA¼5%).</p><p>Fig. 23. Relationship between potential volumetric strain (ε*ν,air) and lique-</p><p>faction resistance ratio defined by DA¼5% criterion (LRRDA¼5%).</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744 741</p><p>tested confining pressure range. It also shows that the</p><p>liquefaction resistance changes from a linear relationships to</p><p>a rounded curve as density increases, which is in good</p><p>agreement with the behavior of Toyoura sand as described</p><p>by Tatsuoka et al. (1982) and Tatsuoka et al. (1986).</p><p>Figs. 19–21 compare the resistance against liquefaction</p><p>between saturated and unsaturated IOF-B with Dc of 93%,</p><p>87% and 81%, respectively. It can be seen that in general,</p><p>under similar density conditions, the resistance against lique-</p><p>faction increases as Sr decreases. As was the case with Inagi</p><p>sand, a noticeable difference in the number of cycles (between</p><p>NDA¼5% and NΔu¼0.9s00) required for liquefaction to take place</p><p>was also observed for the unsaturated IOF-B specimens,</p><p>particularly in those under the relatively dense condition</p><p>(Fig. 19 with Dc of 93%). Note that for the specimens with</p><p>a Dc of 93% and Sr of 72%, the pore water pressure did not</p><p>reach Δu¼0.9s00 before the end of the tests (maximum Δuw</p><p>values of the specimens was less than 0.3s0’). In Fig. 19, the</p><p>liquefaction resistance curves of the IOF-B specimens with a</p><p>Dc of 93% defined by the DA¼5% criterion tend to intersect</p><p>each other as the increase in CSR value, while the curves with</p><p>different values of Sr are rather parallel when using the</p><p>Δu¼0.9s00 criterion. The liquefaction resistance curves</p><p>between the saturated and unsaturated conditions in Figs. 20</p><p>and 21 are generally parallel for the same density condition</p><p>regardless the liquefaction criterion.</p><p>4.2. Discussion on the effect of Sr on liquefaction resistance</p><p>To evaluate the effect of Sr on the RL, liquefaction resistance</p><p>ratio (LRR) is defined as the ratio of RL,unsat to RL,sat under</p><p>either the DA¼5% criterion (LRRDA¼5%) or the Δu¼0.9s00</p><p>criterion (LRRΔu¼0.9s00) for the same soil with otherwise</p><p>similar conditions. Fig. 22 shows the relationship between Sr</p><p>and LRRDA¼5% for the three types of granular media tested in</p><p>this study and other soils used in previous studies by other</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>Table 2</p><p>Conditions of isotropic consolidation tests.</p><p>Media types Dc or Dr (%) s00 (kPa) εν,0.9s00 (%)</p><p>Toyoura sand Dr 76 60 0.33</p><p>Dr 4 60 0.47</p><p>Inagi sand Dc 73 60 1.37</p><p>IOF-B Dc 92 100 0.79</p><p>50 0.73</p><p>Dc 87 100 1.05</p><p>Dc 75 100 1.25</p><p>50 1.54</p><p>Note: s00 here denotes the confining pressure immediately before unloading.</p><p>Fig. 24. Unloading curves of isotropic consolidation tests.</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744742</p><p>researchers. Masa sand (Yasuda et al., 1999) and Niigata sand</p><p>(Ishihara et al., 2001) in Fig. 22 are clean sands with an Fc of</p><p>less than 5%. It can be seen that the test results of Toyoura</p><p>sand in this study match with some of the results of previous</p><p>studies. Though Fig. 22 may imply a monotonic increase trend</p><p>of liquefaction resistance as the reduction in Sr for all tested</p><p>soils, the relationship between Sr and LRRDA¼5% is not unique</p><p>even only for the clean sands under different testing condi-</p><p>tions. It also reveals that the LRRDA¼5% values of Toyoura</p><p>sand are much higher than those of materials with considerable</p><p>fines content (i.e. Inagi sand and IOF-B) under the same Sr.</p><p>Okamura and Soga (2006) considered the effect of the</p><p>compressibility of pore air in the unsaturated soils on</p><p>LRRDA¼5% and proposed a parameter, the potential volumetric</p><p>strain (ε*ν,air) to correlate LRRDA¼5%. ε*ν,air is regarded as</p><p>the volumetric strain of the specimens due to pore air</p><p>compression when the excess pore air pressure equals the</p><p>initial confining pressure (Δua¼s00). It is obtained by applying</p><p>Boyle's law:</p><p>ε�v;air ¼</p><p>s00</p><p>pbþs00</p><p>ð1�SrÞ</p><p>e</p><p>1þe</p><p>ð1Þ</p><p>where pb is the absolute value of back pressure (kPa) and e is</p><p>the void ratio.</p><p>In Fig. 23, the relationship between ε*ν,air and LRRDA¼5%</p><p>is plotted. It is clear that the relationship between LRRDA¼5%</p><p>and ε*ν,air is rather unique for clean sands. However, the data</p><p>of Inagi sand and IOF-B do not follow the trend curve</p><p>proposed by Okamura and Soga (2006), distributing under</p><p>the curve instead.</p><p>The components of volumetric strain of saturated and</p><p>unsaturated soils under undrained conditions can be written as:</p><p>εv;τþεv;s’ ¼ εv;air ð2Þ</p><p>where εν,τ, εν,s0 and εν,air are volumetric strains caused by the</p><p>contraction (or the negative dilatancy) behavior of the soil</p><p>subjected to a cyclic shear loading, a reduction in confining</p><p>pressure (s0) and in the compressibility of pore air ( εν,air¼</p><p>0 for Sr¼100%), respectively. System compliance, membrane</p><p>penetration etc. are not considered in Eq. (2). εν,τ may be</p><p>regarded as the motion breaking the contact between soil</p><p>particles during cyclic loading, while</p><p>both εν,air and εν,s0 may</p><p>be regarded as the motions bridging contact by the self-</p><p>compression of pore air and elastic self-rebounding of the</p><p>particles. In another words, εν,air is the motion inducing loss of</p><p>effective stress (i.e. the motion to trigger the liquefaction) and</p><p>εν,air and εν,s0 are the motion required to recover the effective</p><p>stress (i.e. the motion required to resist liquefaction). The</p><p>percentages of effective stress recovery induced by εν,air and</p><p>εν,s0 are related to the compressibility of the pore air and the</p><p>stiffness of the soil skeleton. Thus, use of the single parameter</p><p>ε*ν,air as an index, which is the maximum value of εν,air under</p><p>the test conditions employed, may be insufficient to represent</p><p>the response characteristics of different soils or the same soil</p><p>under different test conditions. As another index, in this paper,</p><p>the volumetric strain ratio (Rv¼εν,air/εν,s0) is proposed to</p><p>correlate LRR with the volumetric expansion of the specimens</p><p>due to a reduction in confining pressure. Since εν,s0 also exists</p><p>in the saturated condition, Rv can be regarded as the weight of</p><p>εν,air in motions resisting liquefaction.</p><p>To estimate εν,s0 the three types of tested soils, isotropic</p><p>consolidation tests (with loading and unloading processes)</p><p>were conducted on the saturated specimens under the test</p><p>conditions shown in Table 2. After consolidation up to a</p><p>specified initial effective confining pressures (s00), the effective</p><p>confining pressure (s0) was decreased step by step to simulate</p><p>the reduction process of s0 during undrained cyclic loading. It</p><p>should be noted that the degree of saturation affects the</p><p>volumetric strains due to the reduction in confining pressure.</p><p>In this study, however, we used the measurements of the</p><p>saturated specimen for simplicity.</p><p>The relationship between the ratio s0/s00 and εν,s0 during the</p><p>unloading process is shown in Fig. 24. Clearly, this relation-</p><p>ship differs considerably for different materials. Toyoura sand</p><p>specimens under both density conditions (i.e. loose and dense)</p><p>exhibit relatively small volume expansion compared with IOF-</p><p>B. Inagi sand specimen shows a similar magnitude of εν,s0 to</p><p>IOF-B with a Dc of 75%. The magnitude of εν,s0 of IOF-B</p><p>increases as the density decreases, while the effect of s00</p><p>(50 kPa and 100 kPa) seems small. The results also show that</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744 743</p><p>the volume of the specimens may expand significantly when s’</p><p>reduces to a relatively low value, e.g. less than 0.1s00. In</p><p>addition, non-uniform deformation was observed for some</p><p>specimens at very low confining pressure. In this study,</p><p>εν,0.9s00 (i.e. εν,s0 induced by 90% reduction of s00) is used to</p><p>represent εν,s0 in the calculation of Rv. The obtained values of</p><p>εν,0.9s00 are listed in Table 2. Note that Dr values of Toyoura</p><p>sand specimens in Table 2 slightly deviate from those of the</p><p>medium dense specimens or extremely loose specimens of</p><p>Toyoura sand indicated in Table 1. However, since εν,0.9s00</p><p>values of Toyoura sand specimens are only marginally affected</p><p>by the density, εν,0.9s00 values of the specimens with a Dr of</p><p>76% and 4% are conveniently used for medium dense speci-</p><p>mens and extremely loose specimens, respectively, in the</p><p>calculation of Rv.</p><p>Fig. 25(a) shows the relationship between Rv, in which εν,air</p><p>is represented by ε*ν,air, and LRRDA¼5% of the three types of</p><p>granular media. Compared with ε*ν,air (Fig. 23), Rv is better</p><p>correlated with LRRDA¼5% (i.e. the effect of soil types is</p><p>minimized). However, some data are still dispersed in the case</p><p>of IOF-B.</p><p>Since εν,0.9s00 is used in the calculation of Rv, it is more</p><p>reasonable to use εν,0.9air, which is εν,air when pore pressure</p><p>equals 90% of s00, instead of ε*ν,air for calculating Rv.</p><p>Accordingly, using LRRΔu¼0.9s00 is more appropriate than</p><p>LRRDA¼5%. The relationship between the new Rv and</p><p>LRRΔu¼0.9s00 is shown in Fig. 25(b). It can be seen that the</p><p>uniqueness of the relationship is further improved compared</p><p>with Fig. 25(a).</p><p>Due to the limitation of experimental data available from</p><p>this study, it is difficult to conclude that εν,0.9s00 ’ and εν,0.9air</p><p>are the most appropriate parameters for evaluating Rv, while</p><p>the large difference in εν,s0 between the three granular media</p><p>(Fig. 24) suggests that it is necessary to consider εν,s0 based on</p><p>the existing theoretical expression (Eq. (2)) to study the</p><p>liquefaction properties of unsaturated granular media. It must</p><p>also be stressed that the effect of suction on resistance to</p><p>liquefaction and the evaluation of εν,s0 was not discussed in</p><p>this study for the purpose of simplicity. Suction is considered</p><p>another important factor for further study.</p><p>Fig. 25. Relationship between volumetric strain ratio (Rv) and LRR (a) Rv¼</p><p>5. Conclusions</p><p>In this paper, the results of undrained cyclic triaxial shear tests</p><p>on saturated and unsaturated iron ore fines (i.e. IOF-B) and two</p><p>ordinary sandy soils (Inagi sand, Toyoura sand) are presented.</p><p>The liquefaction behaviors of IOF-B under several density</p><p>conditions are evaluated in the light of recent concern regarding</p><p>the liquefaction of solid bulk cargo during maritime transportation</p><p>and the accidents attributed to this phenomenon. In the search for</p><p>a better parameter correlating the liquefaction resistance of</p><p>unsaturated granular media, including those with considerable</p><p>fines content, two existing parameters (Sr and ε*ν,air) are</p><p>examined and a new index (Rv) is proposed. The following</p><p>conclusions can be drawn from this study:</p><p>1. The behaviors of IOF-B are similar to those of ordinary</p><p>sandy soils, for example, the cyclic mobility behavior for</p><p>dense specimens and flow type liquefaction behavior for</p><p>loose specimens are observed under the saturated condition;</p><p>not all specimens reach the zero effective stress state under</p><p>the unsaturated condition; the flow type liquefaction beha-</p><p>vior evolves to cyclic mobility behavior as the saturated</p><p>condition changes to the unsaturated condition of the</p><p>specimen; and the density and liquefaction criterion affect</p><p>the liquefaction resistance curves. It is worth mentioning</p><p>that the effect of confining pressures (50 kPa and 100 kPa</p><p>used in this study) seems to be negligible on the liquefac-</p><p>tion resistance of saturated IOF-B with a Dc of 93%</p><p>and 81%.</p><p>2. It is confirmed that the liquefaction resistance of granular</p><p>media under the unsaturated condition defined by either the</p><p>DA¼5% criterion or the Δu¼0.9s00 criterion is higher than</p><p>that under the saturated condition. However, two existing</p><p>parameters, Sr and the potential volumetric strain, show</p><p>non-unique relationships with the liquefaction resistance</p><p>ratio (LRR) especially when considering materials with a</p><p>considerable fines content.</p><p>3. To consider the effects of pore air compressibility and the</p><p>volume expansion of specimens during cyclic loading on the</p><p>liquefaction resistance of the unsaturated media, a new index,</p><p>ε*ν,air/εν,0.9s0 vs LRRDA¼5% and (b) Rv¼εν,0.9air/εv,0.9s’ vs LRRu¼0.9s00.</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>muril</p><p>Realce</p><p>H. Wang et al. / Soils and Foundations 56 (2016) 732–744744</p><p>volumetric strain ratio (Rv), is proposed to correlate LRR.</p><p>Based on the experimental data obtained in this study, it is</p><p>demonstrated that Rv can minimize the effect of types of</p><p>granular media on liquefaction resistance and exhibits a much</p><p>better correlation with LRR than the degree of saturation and</p><p>potential volumetric strain, the two existing parameters.</p><p>Acknowledgment</p><p>The first author would like to express his gratitude to the</p><p>Ministry of Education, Culture, Sports, Science and Technol-</p><p>ogy of Japan for its financial support during the doctoral</p><p>course. This work was supported by JSPS Grants-in-Aid for</p><p>Scientific Research, Grant numbers 26630219 and 15H04036.</p><p>References</p><p>Ampadu, S.K., Tatsuoka, F., 1993. Effect of setting method on the behavior of</p><p>clays in triaxial compression from saturated to undrained shear. Soils</p><p>Found. 33 (2), 14–34.</p><p>Arab, A., Shahrour, I., Lancelot, L., 2011. A laboratory study of liquefaction of</p><p>partially</p><p>saturated sand. J. Iber. Geol. 37 (1), 29–36.</p><p>Castro, G., 1975. Liquefaction and cyclic mobility of saturated sands. In:</p><p>Proceeding of ASCE, vol. 101, GT6, pp. 551–569.</p><p>Castro, G., Poulos, S.J., 1977. Factors affecting liquefaction and cyclic</p><p>mobility. In: Proceeding of ASCE, vol. 103, GT6, pp. 502–516.</p><p>IMO, 2013. Early implementation of draft amendments to the IMSBC Code</p><p>related to the carriage and testing of iron ore fines. International Maritime</p><p>Organization, DSC.1/Circ.71.</p><p>Gard., 2012. Brazil-liquefaction of bauxite cargoes. Gard. 〈http://www.gard.no/</p><p>ikbViewer/Content/20651235/Gard%20Alert%20Brazil%20Liquefaction%</p><p>20of%20bauxite%20cargoes.pdf〉 (accessed on 26.03.2015).</p><p>Goto, S., Shamoto, Y., 2002. Estimation method for the liquefaction strength</p><p>of unsaturated sandy soil (part 2). In: Proc. 37th Jpn. Nat. Conf. Geotech.</p><p>Engrg., pp. 1987-1988 (in Japanese).</p><p>Huang, Y., Tsuchiya, H., Ishihara, K., 1999. Estimation of partial saturation</p><p>effect on liquefaction resistance of sand using P-wave velocity. In: Proc.</p><p>JGS Symp., 113, 431-434 (in Japanese).</p><p>Isacson, C., 2010a. Re: India-safe shipment of iron ore fines from Indian ports.</p><p>Int. Group Member Circular No.16. 〈http://www.gard.no/ikbViewer/Con</p><p>tent/10129118/Member%20Circular%2016%202010%20India%20Safe%</p><p>20shipment%20of%20iron%20ore%20fines%20from%20Indianports.pdf〉</p><p>(accessed on 26.03.2015).</p><p>Isacson, C., 2010b. Re: Indonesia and the Philippines-Safe Carriage of Nickel</p><p>Ore Cargoes. Int. Group Member Circular No. 23. 〈http://www.gard.no/</p><p>ikbViewer/Content/12143419/Member%20Circular%2023%202010%</p><p>20Indonesia%20and%20the%20Philippines%20%BF%20Safe%20Carriage</p><p>%20of%20Nickel%20Ore%20Cargoes.pdf〉 (accessed on 26.03.2015).</p><p>Ishihara, K., 1993. Liquefaction and flow failure during earthquakes. Geo-</p><p>technique 43 (3), 351–415.</p><p>Ishihara, K., Tsuchiya, H., H., Huang, Y., Kamada, K., 2001. Recent studies</p><p>on liquefaction resistance of sand- effect of saturation. In: Proc. 4th Int.</p><p>Conf. Recent Advance in Geotech. Earthquake Engrg. and Soil Dynamics,</p><p>pp. 1–7.</p><p>Koseki, J., Yoshida, T., Sato, T., 2005. Liquefaction properties of Toyoura</p><p>sand in cyclic torsional shear tests under low confining stress. Soils Found.</p><p>45 (5), 103–113.</p><p>LPC, 2011. Cargo liquefaction problems – sinter feed from Brazil. Loss</p><p>prevention circular, No. 06-11. 〈http://www.gard.no/ikbViewer/Content/</p><p>15758052/06-11%20Cargo%20liquefaction%20problems%20-%20sinter%</p><p>20feed%20from%20Brazil.pdf〉 (accessed on 26.03.2015).</p><p>Mulilis, J.P., Seed, H.B., Chan, C.K., Mitcholl, J.K., Arulanandan, K., 1977.</p><p>Effects of sample preparation on sand liquefaction. In: Proceeding of</p><p>ASCE, vol. 103, GT2, pp. 91–108.</p><p>NILIM, 2011. Report of continuous monitoring of an air injection ground:</p><p>regarding the method of the micro-bubble water injection as a counter-</p><p>measure of liquefaction of residential land (in Japanese). 〈http://www.nilim.</p><p>go.jp/lab/jbg/takuti/ekijyoka/20110513sato.pdf〉 (accessed on 26.03.2015).</p><p>NILIM, 2013. Examination and investigation on the ground dewatering</p><p>method applied on liquefied areas (in Japanese). 〈http://www.mlit.go.jp/</p><p>common/000986855.pdf〉 (accessed on 26.03.2015).</p><p>Nishimura, T., Koseki, J., Fredlund, D.G., Rahardjo, H., 2012. Micro-porous</p><p>membrane technology for measurement of soil-water characteristic curve.</p><p>Geotech. Test. J 35, 201–208.</p><p>Okamura, M., Ishihara, M., Tamura, K., 2006. Degree of saturation and</p><p>liquefaction resistances of sand improved with sand compaction pile. J.</p><p>Geotech. Geoenviron. Eng. 132 (2), 258–264.</p><p>Okamura, M., Soga, Y., 2006. Effects of pore fluid compressibility on</p><p>liquefaction resistance of partially saturated sand. Soils Found. 46 (5),</p><p>695–700.</p><p>Seed, H.B., 1979. Soil liquefaction and cyclic mobility evaluation for level</p><p>ground during earthquakes. In: Proceeding of ASCE, vol. 105, GT2,</p><p>pp. 201–255.</p><p>Seed, H.B., Idriss, M., 1971. Simplified procedure for evaluating soil liquefac-</p><p>tion potential. In: Proceeding of ASCE, vol. 97, SM9, pp. 1249–1273.</p><p>Sherif, M.A., Ishibashi, I., Tsuchiya, C., 1977. Saturation effects on initial soil</p><p>liquefaction. In: Proceeding of ASCE, vol. 103, GT8, pp. 914–917.</p><p>Sze, H.Y., Yang, J., 2014. Failure modes of sand in undrained cyclic loading</p><p>impact of sample preparation. J. Geotech. Geoenviron. Eng. 140 (1),</p><p>152–169.</p><p>Tatsuoka, F., Muramatsu, M., Sasaki, T., 1982. Cyclic undrained stress–strain</p><p>behavior of dense and by torsional simple shear test. Soils Found. 22 (2),</p><p>55–70.</p><p>Tatsuoka, F., Ochi, K., Fujii, S., Okamoto, M., 1986. Cyclic undrained triaxial</p><p>and torsional shear strength of sands for different sample preparation</p><p>methods. Soils Found. 26 (3), 23–41.</p><p>Towhata, I., Maruyama, S., Kasuda, K., Koseki, J., Wakamatsu, K., Kiku, H.,</p><p>Kiyota, T., Yasuda, S., Taguchi, Y., Aoyama, S., Hayashida, T., 2014.</p><p>Liquefaction in the kanto region during the 2011 off the pacific coast of</p><p>Tohoku earthquake. Soils Found. 54 (4), 859–873.</p><p>Tsukamoto, Y., Ishihara, K., Nakazawa, H., Kamada, K., Huang, Y., 2002.</p><p>Resistance of partly saturated sand to liquefaction with reference to</p><p>longitudinal and shear wave velocities. Soils Found. 42 (6), 93–104.</p><p>Unno, T., Kazama, M., Uzuoka, R., Sento, N., 2008. Liquefaction of</p><p>unsaturated sand considering the pore air pressure and volume compres-</p><p>sibility of the soil particle skeleton. Soils Found. 48 (1), 87–99.</p><p>Vanapalli, S.K., Fredlund, D.G., Pufahl, D.E., Clifton, A.W., 1996. Model for</p><p>the prediction of shear strength with respect to soil suction. Can. Geotech.</p><p>J. 33, 379–392.</p><p>Wang, H., Koseki, J., Nishimura, T., 2014. SWCC measurement of two types</p><p>of iron ores. In: Proc. 6th Int. Conf. on unsaturated soils, Unsat2014,</p><p>Sydney, pp. 973–979.</p><p>Wang, H., Koseki, J., Sato, Tan Tian, J., 2015. Experimental evaluation of</p><p>liquefaction resistance of unsaturated sandy soils. In: Proc. 6th Int. Symp. on</p><p>Deformation Characteristics of Geomaterials, Buenos Aires, pp. 299–306.</p><p>doi:10.3233/978-1-61499-601-9-299.</p><p>Yang, J., 2002. Liquefaction resistance of sand in relation to P-wave velocity.</p><p>Geotechnique 5 (4), 295–298.</p><p>Yang, J., Savidis, S., Roemer, M., 2004. Evaluating liquefaction strength of</p><p>partially saturated sand. J. Geotech. Geoenviron. Eng. 130 (9), 975–979.</p><p>Yamaguchi, T., Mori, T., Kazama, M., Yoshida, N., 2012. Liquefaction in</p><p>Tohoku district during the 2011 off the pacific coast of Tohoku earthquake.</p><p>Soils Found. 52 (5), 811–829.</p><p>Yasuda, S., Harada, K., Ishikawa, K., Kanemaru, Y., 2012. Characteristics of</p><p>liquefaction in Tokyo Bay area by the 2001 Great East Japan Earthquake.</p><p>Soils Found. 52 (5), 793–810.</p><p>Yasuda, S., Kobayashi, T., Fukushima, Y., Kohari, M., Simazaki, T., 1999.</p><p>Effect of degree of saturation on the liquefaction strength of Masa. In: Proc.</p><p>34th Jpn. Nat. Conf. Geotech. Engrg., pp. 2071–2072 (in Japanese).</p><p>Yoshimi, Y., Tanaka, K., Tokimatsu, K., 1989. Liquefaction resistance of a</p><p>partially saturated sand. Soils Found. 29 (3), 157–162.</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref1</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref1</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref1</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref2</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref2</p><p>http://www.gard.no/ikbViewer/Content/20651235/Gard%20Alert%20Brazil%20Liquefaction%20of%20bauxite%20cargoes.pdf</p><p>http://www.gard.no/ikbViewer/Content/20651235/Gard%20Alert%20Brazil%20Liquefaction%20of%20bauxite%20cargoes.pdf</p><p>http://www.gard.no/ikbViewer/Content/20651235/Gard%20Alert%20Brazil%20Liquefaction%20of%20bauxite%20cargoes.pdf</p><p>http://www.gard.no/ikbViewer/Content/10129118/Member%20Circular%2016%202010%20India%20Safe%20shipment%20of%20iron%20ore%20fines%20from%20Indianports.pdf</p><p>http://www.gard.no/ikbViewer/Content/10129118/Member%20Circular%2016%202010%20India%20Safe%20shipment%20of%20iron%20ore%20fines%20from%20Indianports.pdf</p><p>http://www.gard.no/ikbViewer/Content/10129118/Member%20Circular%2016%202010%20India%20Safe%20shipment%20of%20iron%20ore%20fines%20from%20Indianports.pdf</p><p>http://www.gard.no/ikbViewer/Content/12143419/Member%20Circular%2023%202010%20Indonesia%20and%20the%20Philippines%20%BF%20Safe%20Carriage%20of%20Nickel%20Ore%20Cargoes.pdf</p><p>http://www.gard.no/ikbViewer/Content/12143419/Member%20Circular%2023%202010%20Indonesia%20and%20the%20Philippines%20%BF%20Safe%20Carriage%20of%20Nickel%20Ore%20Cargoes.pdf</p><p>http://www.gard.no/ikbViewer/Content/12143419/Member%20Circular%2023%202010%20Indonesia%20and%20the%20Philippines%20%BF%20Safe%20Carriage%20of%20Nickel%20Ore%20Cargoes.pdf</p><p>http://www.gard.no/ikbViewer/Content/12143419/Member%20Circular%2023%202010%20Indonesia%20and%20the%20Philippines%20%BF%20Safe%20Carriage%20of%20Nickel%20Ore%20Cargoes.pdf</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref3</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref3</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref4</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref4</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref4</p><p>http://www.gard.no/ikbViewer/Content/15758052/06-11%20Cargo%20liquefaction%20problems%20-%20sinter%20feed%20from%20Brazil.pdf</p><p>http://www.gard.no/ikbViewer/Content/15758052/06-11%20Cargo%20liquefaction%20problems%20-%20sinter%20feed%20from%20Brazil.pdf</p><p>http://www.gard.no/ikbViewer/Content/15758052/06-11%20Cargo%20liquefaction%20problems%20-%20sinter%20feed%20from%20Brazil.pdf</p><p>http://www.nilim.go.jp/lab/jbg/takuti/ekijyoka/20110513sato.pdf</p><p>http://www.nilim.go.jp/lab/jbg/takuti/ekijyoka/20110513sato.pdf</p><p>http://www.mlit.go.jp/common/000986855.pdf</p><p>http://www.mlit.go.jp/common/000986855.pdf</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref5</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref5</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref5</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref6</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref6</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref6</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref7</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref7</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref7</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref8</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref8</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref8</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref9</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref9</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref9</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref10</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref10</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref10</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref11</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref11</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref11</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref11</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref12</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref12</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref12</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref13</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref13</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref13</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref14</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref14</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref14</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref15</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref15</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref16</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref16</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref17</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref17</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref17</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref18</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref18</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref18</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref19</p><p>http://refhub.elsevier.com/S0038-0806(16)30059-2/sbref19</p><p>Effect of saturation on liquefaction resistance of iron ore fines and two sandy soils</p><p>Introduction</p><p>Apparatus</p><p>Testing programs</p><p>Test results</p><p>Effective stress paths and stress strain relationships</p><p>Saturated specimens</p><p>Unsaturated specimens</p><p>Liquefaction resistance</p><p>Discussion on the effect of Sr on liquefaction resistance</p><p>Conclusions</p><p>Acknowledgment</p><p>References</p>