Analysis of point load test as a method for preliminary geotechnical classification of rocks

This paper deals with the analysis of the point load compression test made on irregular-shaped rock fragments, proposed in the late 50’s by Protodiakonov. An ample revision of the literature on the subject has been made, and a series of tests, using seven different types of rock materials, has been developed. The results obtained from these tests showed that parameters generally used in literature to relate the unconfined compressive (or tensile) strength of materials, resulting from point load tests, can lead to scattered results, due mainly to the scale effect, of great evidence in such tests. It seems possible to obtain compressive (and tensile) strength of rocks, if the ratio between failure load and the distance between load application poins, with a 3/2 exponent, is considered, in field work, as being the "point load strength index".

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Resume L’article présente une analyse critique de l’essai de compression sur échantillons irréguliers de roche, proposé par Protodiakonov vers la fin des années 50. Tout d’abord on a fait une révision de la littérature disponible sur le sujet et, après, une série d’essais sur sept types différents de matériaux. Les résultats obtenus ont montré que les paramètres plus utilisés, dans la littérature, pour définir la résistance à la compression (ou traction) des roches, d’après les essais ponctuels, peuvent provoquer une dispersion très importante des résultats. Cependant, il nous semble valable de suggérer la possibilité de déterminer, sur le chantier, la résistance à la compression (ou traction) des roches, si l’on considère le quotient entre la charge de rupture et la distance entre les deux points d’application de cette charge, le dénominateur à la puissance 3/2, comme "l’indice de charge ponctuelle".

     

A computer technique for predicting smoke movement in tall buildings

An approach to the analysis of stack effect has been developed which allows the prediction of internal air flow quantities and associated pressure differentials for specific buildings prior to construction. An example of the application of this analysis is presented for a hypothetical 75-story office building. Note: The authors presented this paper at a symposium on “The Control of Smoke Movement on Escape Routes in Buildings,” sponsored by the Joint Fire Research Organization and held on April 9 and 10, 1969 in Hertfordshire, England.     

Controlein situ du compactage de remblais sous eau

Bulletin of Engineering Geology and the Environment - La fermeture de l'Escaut oriental constitute le couronnement des travaux du Plan Delta aux Pays-Bas. Le danger de l'érosion et de...     

Influences of iron, manganese, and dissolved organic carbon on the hypolimnetic cycling of amended mercury

The biogeochemical cycling of iron, manganese, sulfide, and dissolved organic carbon were investigated to provide information on the transport and removal processes that control the bioavailability of isotopic mercury amended to a lake. Lake profiles showed a similar trend of hypolimnetic enrichment of Fe, Mn, DOC, sulfide, and the lake spike ((202)Hg, purity 90.8%) and ambient of pools of total mercury (HgT) and methylmercury (MeHg). Hypolimnetic enrichment of Fe and Mn indicated that reductive mobilization occurred primarily at the sediment-water interface and that Fe and Mn oxides were abundant within the sediments prior to the onset of anoxia. A strong relationship (r(2)=0.986, n=15, p<0.001) between filterable Fe and Mn indicated that reduction of Fe and Mn hydrous oxides in the sediments is a common in-lake source of Fe(II) and Mn(II) to the hypolimnion and that a consistent Mn:Fe mass ratio of 0.05 exists in the lake. A strong linear relationship of both the filterable [Fe] (r(2)=0.966, n=15, p<0.001) and [Mn] (r(2)=0.964, n=15, p<0.001) to [DOC] indicated a close linkage of the cycles of Fe and Mn to DOC. Persistence of iron oxides in anoxic environments suggested that DOC was being co-precipitated with Fe oxide and released into solution by the reductive dissolution of the oxide. The relationship between ambient and lake spike HgT (r(2)=0.920, n=27, p<0.001) and MeHg (r(2)=0.967, n=23, p<0.001) indicated that similar biogeochemical processes control the temporal and spatial distribution in the water column. The larger fraction of MeHg in the lake spike compared to the ambient pool in the hypolimnion suggests that lake spike may be more available for methylation. A linear relationship of DOC to both filterable ambient HgT (r(2)=0.406, n=27, p<0.001) and lake spike HgT (r(2)=0.314, n=15, p=0.002) suggest a role of organic matter in Hg transport and cycling. However, a weak relationship between the ambient and lake spike pools of MeHg to DOC indicated that other processes have a major role in controlling the abundance and distribution of MeHg. Our results suggest that Fe and Mn play important roles in the transport and cycling of ambient and spike HgT and MeHg in the hypolimnion, in part through processes linked to the formation and dissolution of organic matter-containing Fe and Mn hydrous oxides particles.     

The Effect of Energy-Supply and Performance Indicators on the Performance of Traction-Resource Management Centers

Russian Electrical Engineering - This paper presents the results of a study of the effect of the characteristics of the traction power-supply system on the indicator of the energy supply of...     

Test facility for investigation of heat transfer of promising coolants for the nuclear power industry

The results are presented of experimental investigations into liquid metal heat transfer performed by the joint research group consisting of specialist in heat transfer and hydrodynamics from NIU MPEI and JIHT RAS. The program of experiments has been prepared considering the concept of development of the nuclear power industry in Russia. This concept calls for, in addition to extensive application of water-cooled, water-moderated (VVER-type) power reactors and BN-type sodium cooled fast reactors, development of the new generation of BREST-type reactors, fusion power reactors, and thermonuclear neutron sources. The basic coolants for these nuclear power installations will be heavy liquid metals, such as lead and lithium-lead alloy. The team of specialists from NRU MPEI and JIHT RAS commissioned a new RK-3 mercury MHD-test facility. The major components of this test facility are a unique electrical magnet constructed at Budker Nuclear Physics Institute and a pressurized liquid metal circuit. The test facility is designed for investigating upward and downward liquid metal flows in channels of various cross-sections in a transverse magnetic field. A probe procedure will be used for experimental investigation into heat transfer and hydrodynamics as well as for measuring temperature, velocity, and flow parameter fluctuations. It is generally adopted that liquid metals are the best coolants for the Tokamak reactors. However, alternative coolants should be sought for. As an alternative to liquid metal coolants, molten salts, such as fluorides of lithium and beryllium (so-called FLiBes) or fluorides of alkali metals (so-called FLiNaK) doped with uranium fluoride, can be used. That is why the team of specialists from NRU MPEI and JIHT RAS, in parallel with development of a mercury MHD test facility, is designing a test facility for simulating molten salt heat transfer and hydrodynamics. Since development of this test facility requires numerical predictions and verification of numerical codes, all examined configurations of the MHD flow are also investigated numerically.     

Prediction of seepage water pressure for slope stability at the Gol-E-Gohar open pit mine

Slope stability accidents are one of the leading causes of destruction at open pit mining operations. Such interception of the seepage water results in the water inflow from the surrounding aquifer towards the mine excavations. In order to design an effective drainage scheme for an open pit mine, prediction of water inflow into the pit is essential. These changes have resulted in some failures and instability problems in different parts of Gol-E-Gohar iron open pit mine. It seems that main parameters which effect the failure and instability of the mine slopes are high pressure of groundwater and system of discontinuities (faults, joins, and bedding planes), which intersect the pit walls. The analysis results indicate that stability of the final pit slopes is sensitive to multi-planar failures and confined water in the walls pit is also a factor adversely affecting the stability. Problems associated with groundwater at the site were also assessed with the analyses of piezometric level and groundwater inflow.     

Intensification of nonlinearity by dispersed events in media with structure and generation of various dominant frequencies in P- and S-waves

A model of a continuum with a structure described by infinite order equations of motion is proposed. In case that a wave is very long as compared with the size of the structure, equations are reduced to the fourth-order equations. A closed equation of motion, including nonlinear, dispersed and wave members, is derived. It is shown that solutions in the form of soliton waves exist only in media where wave velocity grows with pressure. In the media, where soliton waves do not exist, quasi-stationary solutions with multiple frequencies prevail. It is found that the nonlinear effect of multiple frequencies is unexpectedly high even for small deformation as dispersion violently intensifies nonlinear events. Moreover, in the domain of small deformation, there exist solutions for longitudinal and transversal waves with the same length and different frequencies. The solutions for the same length waves with different frequencies most often occur in seismology and seismic explorations.