https://communities.bentley.com/members/0161676b_2d00_cdc4_2d00_4414_2d00_b752_2d00_4c803f0a0e4eRecent activity for people in Osman Murat SARSILMAZ's communityen-USTelligent Community 12https://communities.bentley.com/products/geotech-analysis/f/forum/247445/seismic-ovalization-analysis-of-tunnel-permanent-liningsSun, 09 Jul 2023 11:49:11 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:35b953f2-90b1-4827-875a-8af936770605Osman Murat SARSILMAZ<p>Hello to all,</p> <p>We are performing seismic ovalization analysis to calculate&nbsp; stresses on tunnel permanent linings which will be excavated in Andesite Rock Formations, Parameters of the rock formation are as follows:</p> <p>GSI= 40</p> <p>UCS= 30 MPa</p> <p>mi= 25</p> <p>Erm= 2400 MPa</p> <p>First we have done the calcualtions with analytical methods proposed by Wang and assumed no slip condition between tunnel lining and rock for axial loads and full-slip condition for momment and shear force.</p> <p>Then we have done ovalization analysis on plaxis to compare and verify the results with analytical formulations , we modeled the rock formation as lineer elastic material and assuming again&nbsp;<span>no slip condition between tunnel lining and rock for axial loads and full-slip condition for momment and shear force.</span></p> <p><span>We have concluded similar results between analytical method and plaxis ovalization analysis. But there was a problem, we saw from the results that the axial tension loads came from seismic calculations are way too much from static compression axial loads from static analysis, and when we add this forces to seismic axial loads, it leads to axial tension forces around 2000 kN, which we were not expect such amount of tension.</span></p> <p><span>The interaction diagram of the tunnel liningis as follows:</span></p> <p><span></span></p> <p><span><img style="max-height:232px;max-width:422px;" height="232" src="/resized-image/__size/844x464/__key/communityserver-discussions-components-files/343671/pastedimage1688902892019v1.png" width="422" alt=" " /></span></p> <p><span></span><span>Then we tried to re-model the plaxis model with a non-lineer material model such as Mohr-Coulomb model to see the difference and we saw that there were no axial tension load on tunnel lining for MC model. and the amount of axial load on compression was similar to linear elastic model</span></p> <p><span></span></p> <p><span>Below you can see the results of both cases:</span></p> <p><span></span><span><img style="max-height:259px;max-width:782px;" height="259" src="/resized-image/__size/1564x518/__key/communityserver-discussions-components-files/343671/pastedimage1688903002952v2.png" width="782" alt=" " /></span></p> <p><span>These results make confusions on reinforcement design of the lining, the regulations which we have to follow are suggesting to use analytical methods, but it is resulting too much axial tension on lining.</span></p> <p><span>We are thinking that especially for this kind of good rock can act linear-elastic while seismic event. but the axial tensions force on lining taking us to put too much reinforcement in lining.&nbsp;</span></p> <p><span>Are there anyone who experienced the same results? and how to solve it?</span></p> <p><span>Thanks in advance for the helps</span></p><div style="clear:both;"></div>https://communities.bentley.com/achievements/460ac7df-7ccc-4c42-a204-9e05eef3be09Sun, 09 Jul 2023 08:37:53 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:e3a3e3a1-1b7d-45eb-afc9-a759390f5a98Ask a question in a forum.