泥质粉砂岩地层中后行盾构隧道近接施工对大断面矿山法隧道的影响研究

Study on the Influence of Approaching Construction of the Trailing Shield-driven Tunnel on the Large-section Mined Tunnel in Argillaceous Siltstone Stratum

两条以上隧道近距离施工时,将导致既有隧道与新建隧道结构的受力变化,带来工法、工序与施工对策优化等问题。文章以长沙轨道交通3号线盾构隧道近接大断面矿山法隧道施工为工程依托,针对泥质粉砂岩地层,采用数值模拟和模型试验的手段,研究盾构隧道近接矿山法隧道施工的影响规律,并基于地表沉降准则提出影响分区。研究表明:盾构法隧道施工中,盾构开挖距离研究断面1倍洞径至研究断面完成管片拼装这一过程,是引起对应地表沉降增加及既有矿山法结构附加位移增长的主要阶段;对矿山法隧道结构的影响以竖向附加变形为主,具体表现为矿山法隧道整体上浮,越靠近盾构隧道的结构受影响越大;内力影响表现为矿山法隧道结构内力不均匀变化,靠近盾构隧道一侧结构受压加强,远离盾构隧道一侧结构易发生受拉破坏。

Adjacent construction of more than two tunnels will cause force changes of both existing and new tun? nels, and it′ s necessary to consider optimization issues of construction method, procedure, countermeasures and so on. Based on the construction of the shield-driven tunnel approaching the large-section mined tunnel of Changsha metro line 3, the numerical simulation and model test methods were adopted to study the effect of shield-driven tunnelling on adjacent mined tunnel in argillaceous siltstone stratum, and a concept of influence zoning was proposed in light of the criterion of ground surface settlement. Research results show that increase of corresponding surface settlement and additional displacement of existing mined tunnel are mainly caused during the process of shield driving which starts from 1 time tunnel diameter away from the studied section and finishes at completion of segment erection at the studied section;in terms of the effect on the mined tunnel, vertical additional deformation is of the main form and it presents as overall tunnel heaving, the closer the existing tunnel structure to the shield-driven tunnel, the greater the influence;regarding the influence on internal force, it is manifested in uneven change of internal force of the existing mined tunnel structure, the existing tunnel structure near the shield-driven tunnel is more compressed and it is liable to occur tensile failure at the side far away from the shield-driven tunnel.