Inference on the Surveying Methods at the 8th Century in Japan
Issue:
Volume 8, Issue 5, September 2020
Pages:
106-116
Received:
30 July 2020
Accepted:
22 August 2020
Published:
17 September 2020
Abstract: Ancient regional records on geography named Fudoki were compiled in Japan at the 8th century. There were about 60 provinces at that time, but only 5 Fudoki (transcripts) have remained at present. Among them, Izumo Fudoki (edited in 733) is not only almost complete, but also contains detailed geographic data (surveying data) not found in the others. The surveying data are distances between major points, heights and sizes of mountains, sizes of lakes and isles etc. However, there are many differences when comparing these surveying data with actual sites. The Fudoki researchers had tried many times to interpret the relationships between the two, but many unclear points have remained. During the time, we civil engineers had little interest in the Fudoki. In this paper, we estimated the surveying methods by comparing the Fudoki data with map data and confirming the sites, then obtained the following conclusions. The distances were almost correct, the heights of the mountains were converted using the number of steps, the perimeters of the mountains were calculated with the trails as diameters, and the sizes of the lakes and isles were the lengths of the waterways. The surveying methods at that time were simple, but the results obtained were practical. We think that these ancient surveying methods were widely used, not in one region or one period.
Abstract: Ancient regional records on geography named Fudoki were compiled in Japan at the 8th century. There were about 60 provinces at that time, but only 5 Fudoki (transcripts) have remained at present. Among them, Izumo Fudoki (edited in 733) is not only almost complete, but also contains detailed geographic data (surveying data) not found in the others....
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Numerical Modelling of Seismic Site Response at Large Strains: A Parametric Study
Francesco Di Buccio,
Alessandro Pagliaroli
Issue:
Volume 8, Issue 5, September 2020
Pages:
117-127
Received:
2 October 2020
Accepted:
22 October 2020
Published:
11 November 2020
Abstract: The numerical analysis of seismic site response at large strains should adopt constitutive models able to guarantee not only a correct modelling of stiffness and damping properties but also a compatibility with the shear strength of the materials. The traditional hyperbolic models used in nonlinear analyses are generally calibrated on stiffness and damping curves and therefore does not necessarily match the soil shear strength. An inaccurate modelling of shear strength can lead to unrealistic predictions of the seismic site response with results that are not necessarily conservative: underestimation or overestimation of the computed surface response depends on the difference between the maximum shear stress implied by the adopted hyperbolic nonlinear model and the real soil shear strength. In this paper, over 1900 one-dimensional parametric analyses on ideal sand and clay deposits were executed with DEEPSOIL software. A first comparison was undertaken between equivalent linear and nonlinear analyses; then the nonlinear analyses were addressed to study the influence of shear strength as an input parameter on the results of numerical site response analyses. In particular two strategies to take into account the soil shear strength were considered: an adjustment procedure associated to the standard MKZ hyperbolic model and the GQ/H model which allows the shear strength to be explicitly defined as input parameter of the analyses. This parametric study made it possible to define preliminary threshold shear strain values, beyond which it is necessary to execute numerical analyses with more advanced models or procedures, able to capture the real behavior of the soil at large strains. Indicatively above shear strains of 0.1%, traditional nonlinear models neglecting soil strength can provide unrealistic results, with important overestimation of the seismic motion (up to 30% in terms of PGA at the surface).
Abstract: The numerical analysis of seismic site response at large strains should adopt constitutive models able to guarantee not only a correct modelling of stiffness and damping properties but also a compatibility with the shear strength of the materials. The traditional hyperbolic models used in nonlinear analyses are generally calibrated on stiffness and...
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