Geomechanik und Tunnelbau最新文献

The geometry of the disc cutter is one of the most important factors in the rock cutting process of mechanized tunnel boring machines (TBMs). However, during excavation, the optimal conditions of the disc cutter are not constant due to disc cutter wear. One of the most significant consequences of cutter wear is the increase in the contact area of the disc cutter with the rock so when the wear of the cutter exceeds its maximum limits, it should be replaced. Therefore, this study will examine the effect of disc cutter wear on TBM operational parameters such as thrust force, net penetration rate, and specific energy. In order to achieve this, six types of worn 17“ disc cutters have been studied graphically, and a method for calculating the surface of contact between the disc cutter and rock as a function of the cutter tip width has been developed. Moreover, a new equation has been proposed to predict normal and rolling cutting forces whose results are in good agreement with the reported laboratory values. As a final step, the hard rock TBM parameters of the Kani Sib water conveyance tunnel have been studied after replacement of worn disc cutters. The results show that replacing the worn disc cutters leads to an increase in penetration rate and a decrease in thrust force, resulting in an increase in specific penetration. On average, specific penetration increases by ≈35 %.

Water storages for energy production in mountain valleys or snow retention basins on mountain slopes or mountain ridges are common buildings in Alpine regions. When such water reservoirs are situated on or nearby of a large slow-moving landslide, low factors of safety and ongoing deformation of the reservoir structure – or parts of it – need to be handled in some cases. Questions about the justification but also the reliability of reservoirs influenced by such landslides need to be discussed. Verification procedures which proof a save operation of the reservoir over time but also an estimation of the behaviour of the reservoir influenced by the landslide for exceptional load cases need to be investigated. In this paper main issues and problems related to such questions are discussed for reservoirs in the design as well as in the operation state which are influenced by such slow moving landslides.

For over 25 years, the AT Pipe Umbrella System has been used to cope a wide variety of challenges such as fractured rock, fault zones, loose rock, slope debris areas or backfill, thus enabling safe and efficient tunnelling. The first application in 1998 in the Sieberg Tunnel – a 6.48 km long tunnel on the Vienna-Salzburg high-speed railway line – was a complete success and the starting point for a long-lasting success story. (Source: DSI Underground)

In the future large energy storage facilities will play a key role in district heating systems that transport heat energy through tube systems with water as transport media. Energy storages enable storage of renewable energy and industrial waste heat through flexible buffer heat storage and allow a reduction in installed capacities of heat supply stations. In this article, the application of water-filled rock caverns for the use of large thermal energy storages is analysed. A key issue is the energy loss over the month/year. Therefore, this study focuses on the quantification of energy losses from water-filled rock caverns by means of numerical analysis. Three different rock cavern geometries are analysed, varying rock conductivity parameter and varying temperature profiles of the water storage. By simulations with the software COMSOL it could be shown that (i) the energy losses of underground caverns are only 25 % compared to the energy losses from the currently used insulated steel tanks located above ground, (ii) the energy losses can be further decreased by the application of a thermal insulation layer and (iii) the energy losses decrease over the lifetime due to the reducing temperature gradients in the surrounding rock. Since cavern reservoirs can be operated for more than 100 years, these findings are of great relevance and shall be further investigated with respect to economical assessment.