Mechanical behavior of iron ore tailings under standard compression and extension triaxial stress paths

The disposal of mining tailings has increasingly focused on the use of dry stacks.These structures offer more security since they use filtered and compacted material.Because of the construction method and the heights achieved,the material that compounds the structure can be subjected to different stress paths along the failure plane.The theoretical framework considered in the design of these structures generally is the critical state soil mechanics(CSSM).However,the data in the literature concerning the uniqueness of critical state line(CSL)is still controversial as the soil is subjected to different stress paths.With respect to tailings,this question is even more restricted.This paper studies two tailings with different gradings due to the beneficial processes over extension and compression paths.A series of drained and undrained triaxial tests was conducted over a range of initial densities and stress levels.In the q-p'plane,different critical stress ratio(M)values were obtained for compression and extension stress paths.However,the critical state friction angle is very similar with a slightly higher critical state friction angle for extension tests.Curved stress path dependent CSLs were obtained in the n-lnp0 plane with the extension tests below the CSL defined in compression.Regarding the fines content,the studied tailings presented very similar M and critical state friction angle values.However,the fines content af-fects the volumetric behavior of the studied tailings and the CSLs on the n-lnp0 plane shift downwards with the increasing fines content for compression and extension tests.In relation to dilatancy analysis,the fines content did not present an evident influence on the dilatancy of the materials.However,different values of mean stress ratio N were obtained between compression and extension tests and can corroborate the existence of non-unique CSLs for these materials.

振动拉压扭剪三轴仪及其试验研究

简要介绍了国内首创的振动拉压扭剪三轴仪的主要特征，给出了饱和标准砂的部分动力试验结果，并对其作了必要的分析研究。

Evaluation of the ＂Harmony/Balance Value＂ on the Development of the Sensorial Quality of EVOOmExperiences in Germany and Europe

Since 2015 the methodology of the harmony value in the framework of the official organoleptic assessment has been accredited by the German authorities. It initiated additional background for this parameter which is set on top of the Official Paneltest （Standard IOC/T15/Reg. （EWG） 2568/91 in its actual version） which classifies Olive oil in the relevant classifications ＂extra virgin＂, ＂virgin＂ or ＂virgin lampante＂. This study will proof the possible accuracy of this additional parameter ＂harmony/balance＂ and the benefits which arise with this additional parameter for all stakeholders. The German Olive Oil Panel （DOP） is practicing this extended methodology for the sensory evaluation of extra virgin olive oil since 2003. In addition to the verification of the category ＂extra virgin＂ the Panel is continuously training for additional descriptors used to appraise the quality-discrimination for this category. But in case the panel decides for a valid median of a defect the panel supervisor （PSV） will set the harmony level to zero. In the focus is the additional attribute called ＂harmony＂ （in some world areas called ＂balance＂--both mean a quantification of the specific overall quality with one single parameter） which is responsible for this advancement in the methodological approach. Using ＂harmony/balance＂ （H/B） as a quality-factor, the discrimination between bad, average, good, very good and premium quality within the category of EVOO became possible. ＂Harmony＂ includes olfactory, tactile and kinesthetic stimuli and is evaluated on a bipolar 100 mm scale, which leads to this parameter from ＂average＂ in the center to ＂complex/harmonious＂ on one side or to ＂totally disharmonious＂ on the other side. In the study at hand we are able to prove the development of qualities in the framework of the accredited Panel in German speaking countries over more than 10 years. In this study the development of the increasing quality can be proved in yearly figures of the DOP. The trend could be disturbed however in case of climatological circumstances or orders from outside Germany with over proportional low qualities. The official organoleptic assessment method of IOC/EC separates defect free from defected olive oils and is marking the olive oils with a relevant label of classification （EV, V, Lampant）. The additional step to evaluate the harmony value----carried out by the same panel during the same procedure--is quantifying the category of EVOO in relevant quality sectors. This study shows on one side the progress of this method in German speaking countries and their supporting companies. On the other side it revealed the quality problems which arise in markets like the private label/low price （PL/LP） sections in other countries of the European Union. This important market segment covers today about 75%-80% of the market. The IGO study （2015） proved that from 70 samples out of 16 European countries 58.5% （41 samples） have been analyzed as defect; only 41.5% （29 samples） matched the classification EVOO. And from these 29 samples 18 have been evaluated with the additional parameter ＂harmony/balance＂ as ＂lower standard＂ or ＂not sufficient＂. The long experience with this additional parameter is able to stabilize and quantify the quality of EVOO in favor of all stakeholders.