新建隧道上穿既有输水隧洞近接施工静动力研究

Static and dynamic response study on the close connection construction of the new tunnel passing through the existing water conveyance tunnel

通过三维弹塑性有限元方法对新建隧道上穿既有输水隧洞近接施工静、动力响应进行了研究,并提出交叉段工程控制措施。结果表明:采用上下台阶法开挖引起的输水隧洞位移较小,拉、压应力增量均满足要求;当新建隧道上台阶掌子面位于输水隧洞正上方时,控制爆破进尺不大于1.0 m可使爆破振速满足要求;爆破进尺为1.0 m时,输水隧洞最大应力小于喷射混凝土极限强度;本文施工方法可有效控制新建隧道开挖对输水隧洞衬砌结构产生的有害影响。研究成果与方法可为类似工程提供参考。

The static and dynamic response of the new tunnel passing through the existing water conveyance tunnel are studied by the three-dimensional elastic-plastic finite element method,and the engineering control measures of the crossing section are put forward. The results show that the displacement of the water tunnel caused by the upper-lower-step excavation of the new tunnel is small,and the increment of both tensile and compressive stress can meet the requirements;when the upper step face of the new tunnel is straightly above the water tunnel,the blasting vibration speed can meet the requirements by controlling the blasting footage not more than 1.0 m;the maximum stress of the water tunnel is less than the critical strength of shotcrete when the blasting footage is 1.0 m;the construction method in this paper can effectively control the harmful influence of the new tunnel excavation on the lining structure of the water conveyance tunnel. The research results and presented methods can provide reference for similar projects.