基于流固耦合的盾构地中对接法管片松动研究

Study on Segment Loosening of Shield Docking Method Based on the Coupling of Stress-Seepage

盾构地中对接法是指2台盾构机相向掘进至某点对接,然后在地层中弃壳解体的方法,适用于水域、山川和城市密集区。通过建立应力-渗流耦合模型,研究后行隧道开挖和推进千斤顶推力卸载对先行隧道环缝的影响,并基于环缝张开量提出防松动环设计参数。结果表明:先行隧道开挖时,环缝张开量随开挖步增加而增加,错台量受隧道顶部下沉和管片张开影响出现2个波动;后行隧道开挖时,环缝张开量随隧道开挖步增加而增加,错台量随隧道开挖步增加而减小;其次,通过提高顶推力大小能有效减小开挖扰动造成的影响,但在较大顶推力下,弃壳解体时会引起环缝发生明显的二次张开;为了控制张开量在合理范围内,增加钢环厚度能有效减小防松动环应力和变形。

Shield docking is that two tunneling machines dig opposite to each other to a certain point,and then discarding shell in the stratum,which is suitable for waters,mountains and dense urban areas.Through establishment of stress-seepage coupling model,influence of subsequent tunnel excavation and thrust unloading of propulsion jack on annular joints of preceding tunnel was studied,and design parameters of anti-loosening ring were proposed based on opening amount of circumferential.The results show that the opening amount increases with the increase of excavation steps,and misdisplacement amount fluctuates two times due to stratum subsidence at the top of tunnel and opening of segment.In the process of subsequent tunnel excavation,opening amount increases with the increase of tunnel excavation steps,while displacement decreases with the increase of tunnel excavation steps.Secondly,the influence of excavation disturbance can be effectively reduced by increasing thrust size.However,when the abandoned shell is disintegrated,there will be obvious secondary opening of annulus.In order to control the opening amount in a reasonable range,increasing ring thickness can effectively reduce the stress and deformation of anti-loose ring.