Fakulteta za gradbeništvo, prometno inženirstvo in arhitekturo Univerze v Mariboru
Abstract
The seismic safety of underground structures (culvert, subway, natural-gas and water-sewage systems) plays a major role in sustainable public safety and urban development. Very few experimental data are currently available and there is no generally accepted procedure to estimate the dynamic pressures acting on these underground structures. This study aims to enhance the state of the prevalent information necessary to understand the dynamic behaviour of box culverts and the stresses acting under dynamic excitations through experimental analyses. For this purpose, a series of shaking-table tests were conducted on box-type culverts buried in dry sand. To simulate the free-field boundary conditions, a laminar box was designed and manufactured for use with a 1-g shake table. Two culvert models having different rigidities were tested under various harmonic motions in order to examine the effect of the flexibility ratio on dynamic lateral soil pressures. Based on the test results, a simplified dynamic pressure distribution acting on the sidewalls of the culvert model was suggested. Then, a dynamic lateral coefficient was defined for the proposed peak pressure value in the distribution. The values of this coefficient were obtained as a function of the shear strain by considering the relative stiffness between the soil and the underground structure.Potresna varnost podzemnih objektov (prepusti, podzemne železnice, sistemi za oskrbo z zemeljskim plinom in vodo), igra pomembno vlogo v trajnostni javni varnosti in urbanem razvoju. Ne poznamo splošno sprejetega postopka za oceno dinamičnih pritiskov, ki delujejo na podzemne objekte. Prav tako je na voljo zelo malo eksperimentalnih podatkov za oceno dinamičnih pritiskov. S študijo želimo izboljšati razumevanje dinamičnega obnašanja škatlastih prepustov in pritiskov, ki delujejo pri dinamičnih vzbujanjih s pomočjo eksperimentalnih analiz. V ta namen smo izvedli niz preizkusov na potresni-mizi na škatlastih prepustih zakopanih v suhem pesku. Za simulacijo robnih pogojev prostega polja, smo za uporabo v 1 g potresni mizi zasnovali in izdelali laminarno škatlo. Na dveh modelih prepustov, ki imata različne togosti smo v raznih harmoničnih gibanjih preučili vpliv razmerja prožnosti na vrednosti dinamičnih bočnih pritiskov tal. Na podlagi rezultatov preskusov predlagamo poenostavljeno porazdelitev dinamični pritiskov, ki delujejo na stranske stene modela prepusta. Za predlagano vrhnjo vrednost tlaka v porazdelitvi tlakov smo definirali dinamični bočni koeficient. Vrednosti tega koeficienta so funkcija strižnih specifičnih deformacij z upoštevanjem relativne togosti med tlemi in podzemno konstrukcijo
