Increase Of Stability Of Underground Works
Free (open access)
139 - 147
K. Weiglová & P. P. Procházka
In this paper the influence of additional structural precaution is studied for an exceptional tunnel facing in extraordinarily difficult conditions. In the case considered here artificial roofing is created by a system of horizontally drilled reinforced piles, which are prepared before drilling current purchase in the frame of tunnel engineering. They are positioned at three height levels above the expected vault (calotte) of the future tunnel, but in the model only one level is assumed (the others are built up for the sake of safety). The influence of the roofing has been verified on two independent models (with and without roofing), treated both experimentally and numerically. Both physical scale models (experimental) and the numerical approach confirmed extremely high improvement of long-lasting stability of the underground work and settlement of the overburden. Using coupled modeling (experimental and numerical) enabled one to quantify the values of the necessary parameters. In numerical models the influence of pile roofing was measured in deformation and stress states of the rock mass. From the results obtained during numerical experiments with different types of roofing the deformation of the overburden was basically restricted. Depending on the material, the deformation dropped by as much as 95 percent in comparison to the non-reinforced case. In the paper the approach consisting of couple modeling – experimental and numerical – will be described. The experiments are prepared on scale models in stands (basins with glazed front sides and the length of 2–6 m), where physically equivalent materials simulate the real situation. Based on similarity rules very good agreement with reality is attained. Keywords: scale modeling, stability of underground works, tunnel face, coupled modeling, artificial roofing.
scale modeling, stability of underground works, tunnel face, coupled modeling, artificial roofing.