Seismic Behavior of Nailed Soil Massifs

Soil nailing technology can be successfully applied to strengthen natural soil massifs in seismic regions, provided adequate analysis is available. Conventionally, the design of soil nailing is performed iteratively: firstly parameters of nailing and their distribution are assigned, the safety factor of the nailed massif is calculated, if its value is less than 1 then nailing parameters are reassigned, etc. Such “trial and error” approach is laborious and especially so, because different types of ULSs shall be analyzed. The method, discussed in the paper, is based on assumption that the effect of nailing in soil with internal cohesion c=c(x,y) could be simulated by equivalent internal cohesion Δc=Δc(x,y) (deficit) of unreinforced massif. Formulae for calculating nailing parameters are determined on the basis of deficit distribution. A MathCad code has been developed, examples are given. The method can be easily applied to assess seismic stability of nailed soil massifs

Initial observations of fine plasma structures at the flank magnetopause with the complex plasma analyzer SCA-1 onboard the Interball Tail Probe

International audienceThe fast plasma analyzer EU-1 of the SCA-1 complex plasma spectrometer is installed onboard the Interball Tail Probe (Interball-1). It provides fast three-dimensional measurements of the ion distribution function on the low-spin-rate Prognoz satellite (about 2min). The EU-1 ion spectrometer with virtual aperture consists of two detectors with 16 E/Q narrow-angle analyzers and electrostatic scanners. This configuration allows one to measure the ion distribution function in three dimensions (over 15 energy steps in 50 eV/Q?5.0 keV/Q energy range in 64 directions) in 7.5 s, which makes it independent of the slow rotation speed of the satellite. A description of the instrument and its capabilities is given. We present here the preliminary results of measurements of ions for two cases of the dawn low- and mid-latitude magnetopause crossings. The properties of observed ion structures and their tentative explanation are presented. The 12 September 1995 pass at low latitude at about 90° solar-zenith angle on the dawn side of the magnetosphere is considered in more detail. Dispersive ions are seen at the edge of the magnetopause and at the edges of subsequently observed plasma structures. Changes in ion velocity distribution in plasma structures observed after the first magnetopause crossing suggest that what resembles multiple magnetopause crossings may be plasma blobs penetrating the magnetosphere. Observed variations of plasma parameters near magnetopause structures suggest nonstationary reconnection as the most probable mechanism for observed structures

Upward high-energy field-aligned electron beams above the polar edge of auroral oval: observations from the SKA-3 instruments onboard the Auroral Probe (Interball-2)

A new phenomenon was found at the polar edge of the auroral oval in the postmidnight-morning sectors: field-aligned (FA) high-energy upward electron beams in the energy range 20–40 keV at altitudes about 3RE, accompanied by bidirectional electron FA beams of keV energy. The beam intensity often reaches more than 0.5·103 electrons/s·sr·keV·cm2, and the beams are observed for a relatively long time (~3·102–103s), when the satellite at the apogee moves slowly in the ILAT-MLT frame. A qualitative scenario of the acceleration mechanism is proposed, according to which the satellite is within a region of bidirectional acceleration where a stochastic FA acceleration is accomplished by waves with fluctuating FA electric field components in both directions.Key words. Ionosphere (particle acceleration; wave-particle interactions) · Magnetospheric physics (magnetosphere-ionosphere interactions)</p

Initial observations of fine plasma structures at the flank magnetopause with the complex plasma analyzer SCA-1 onboard the Interball Tail Probe

The fast plasma analyzer EU-1 of the SCA-1 complex plasma spectrometer is installed onboard the Interball Tail Probe (Interball-1). It provides fast three-dimensional measurements of the ion distribution function on the low-spin-rate Prognoz satellite (about 2min). The EU-1 ion spectrometer with virtual aperture consists of two detectors with 16 E/Q narrow-angle analyzers and electrostatic scanners. This configuration allows one to measure the ion distribution function in three dimensions (over 15 energy steps in 50 eV/Q–5.0 keV/Q energy range in 64 directions) in 7.5 s, which makes it independent of the slow rotation speed of the satellite. A description of the instrument and its capabilities is given. We present here the preliminary results of measurements of ions for two cases of the dawn low- and mid-latitude magnetopause crossings. The properties of observed ion structures and their tentative explanation are presented. The 12 September 1995 pass at low latitude at about 90° solar-zenith angle on the dawn side of the magnetosphere is considered in more detail. Dispersive ions are seen at the edge of the magnetopause and at the edges of subsequently observed plasma structures. Changes in ion velocity distribution in plasma structures observed after the first magnetopause crossing suggest that what resembles multiple magnetopause crossings may be plasma blobs penetrating the magnetosphere. Observed variations of plasma parameters near magnetopause structures suggest nonstationary reconnection as the most probable mechanism for observed structures