Abstract

Under hösten 2013 offentliggjorde den svenska regeringen att man vill investera i att bygga ut Stockholms tunnelbana. Denna utbyggnad innefattar nio nya stationer, Sofia på Södermalm är en av dessa stationer. På grund av platsens förutsättningar kommer stationen bli en av de djupaste i världen. Detta förslag utnyttjar dessa förutsättningar för att sammankoppla gatunivån med den underjordiska perrongen och ger den vardagliga upplevelsen av rymd, atmosfär, ljus och tomrum en central position. Förslaget innefattar ett hundra meter djupt schakt, två hisschakt, ett publikt torg park och tunnelbaneperrong.  During the autumn of 2013 the Swedish government announced that they intend to invest in expanding the Stockholm Metro. The expansion includes nine new stations; Sofia on Södermalm is one of them. The conditions of the site make the station to one of the deepest in the world. This proposal makes use of these conditions to connect the street level and the underground platform level and give the everyday experience of space, atmosphere, light and void a central position. The proposal comprises a hundred meters deep shaft, two elevator shafts, a public square park and train platform. 

Abstract

It is known that the initially proposed circular/spherical rigid particle models are not able to match the ratio of the compressive strength to tensile strength that occurs in rock and the predicted macroscopic friction angle was much lower than the known hard rock experimental values. For this reason, several enhancements have been proposed to address these issues, namely the use of a clumped particle logic, the increase of the number of contacts per particle, the adoption of polygonal/polyhedral grain structures. A flexible 2D DEM based particle model that allows deformable particles to interact in a simplified away is presented. The flexible particle model is tested using biaxial tests and Brazilian tests. The results obtained are compared with those obtained with a rigid particle model with similar contact strength properties and with a flexible particle model, where the flexibility is due to the inner discretization of the grain with smaller particles. The results show that the proposed flexible particle model can predict a behaviour similar to a flexible particle model through inner particle discretization that is more computationally demanding. It is also shown that when compared with a rigid model, the flexible model predicts more reasonable indirect tensile strength to direct tensile strength ratio and requires a smaller value of contact fracture energy to give a good agreement with known experimental data.