European analytical calculations compared with a full-scale Brazilian piled embankment

Measurements have been carried out in a full-scale Brazilian basal reinforced piled embankment. The subsoil beneath the geosynthetic reinforcement (GR) had been excavated before the installation of the reinforced embankment. The embankment was relatively thin in comparison to the pile cap spacing, resulting in relative much load on the GR. GR strains and settlements have been measured making it possible to validate analytical models. Many analytical design models for the design of piled embankments distinguish two calculation steps; calculation step 1; the arching and calculation step 2 ; the load deflection behaviour of the GR. This papser presents the comparison of the full-scale test with a new step 1 - model ; the Concentric arches model (Van Eekelen et al. 2013) and several step 2 models. The new concentric arches model is an extension on the models of Hewlet and Randolph (1988) and Zaeske (2001) and takes into account the 3D nature of the arching. The new model was developed because experiments had showed a load distribution on the GR in a piled embankment that could not be explained with the existing models. The new model does explain the measured load distribution

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta