Interakce primárního tunelového ostění s horninovým masivem ve vztahu k zatížení sekundárního ostění

Abstract

Progressive degradation of shotcrete can be an important problem in terms of reliability, mainly because an accurate estimate of the reduced load-bearing capacity of the primary lining is difficult to predict over the required tunnel life. The standard design of the double lining is based on the assumption that after the degradation of the primary lining, the secondary lining will take over all the load that this primary lining carried before the degradation. However, many monitoring measurements in the secondary lining document that this standard assumption is not entirely objective and that due to the cooperation of the primary lining with the rock mass, the final load of the secondary lining is lower (in some cases practically zero) than the standard approach. According to these assumptions, the aim of this thesis is to define an alternative design approach called DPL: Degraded Primary Lining, which could be effectively implemented in everyday practice in the design of optimal concrete double linings. This diploma thesis deals first with the illustration of the DPL approach on a model example and the subsequent application of this approach in the Dětřichov tunnel using numerical modeling. The first theoretical part describes the issue of double lining of the tunnel using the traditional method. In the second part of the diploma thesis, the gradual load transfer from the surrounding rock to the secondary lining of the model example at different degrees of degradation of the primary lining is first analyzed, then this method is applied to the real project of the Dětřichov tunnel. Mathematical models are performed using the Plaxis 2D program.