哈尔滨地铁粉质黏土地层隧道台阶开挖法围岩稳定性评价

Stability Evaluation of Surrounding Rocks of Silty Clay Strata Tunnel Step Excavation Method in Harbin Metro Tunnel

依托哈尔滨地铁粉质黏土隧道工程,基于超前小导管支护作用机理,建立了超前小导管支护下双参数的弹性地基梁理论模型,开展了超前小导管支护作用下的隧道掌子面稳定性评价。结果表明,对于V级围岩,无须采用超前导管支护便可保证掌子面稳定;对于Ⅵ1级围岩,须采用超前导管支护,并依据工程具体情况决定是否注浆;对于Ⅵ2级围岩,因其土质较差,超前小导管支护无法保证掌子面稳定,须采用深孔注浆加固技术或施加超前管棚支护。基于收敛约束法进行了隧道洞身及衬砌结构稳定性评价,结果表明,支护结构的承载力满足施工安全要求,但Ⅵ1、Ⅵ2级粉质黏土隧道应借助超前支护,以保证围岩稳定性。

Based on the silty clay strata tunnel step excavation project of Harbin Metro,and the mechanism of advanced small pipe support function,the study establishes two-parameter elastic foundation beam theoretical model under the support of advanced small pipe,and develops tunnel face stability evaluation of the support function of advanced small pipe.The results show that it is unnecessary to adopt advanced small pipe support to guarantee the stability of tunnel face for V class surrounding rock.It is necessary to adopt advanced small pipe support,and determine to slip casting according to the specific situation of the engineering forⅥ1 class surrounding rock.Because of its bad soil texture,advanced small pipe can’t guarantee the stability of the tunnel face,so it is necessary to adopt deep hole grouting reinforcement technology or the addition of advance pipe shed support forⅥ2 class surrounding rock.Based on constriction method,the study evaluates the stability of tunnel hole and lining structure.The results show that the bearing capacity of supporting structure satisfies the construction safety requirements,but silty clay strata tunnel ofⅥ1 andⅥ2 class should borrow from advanced support to guarantee the stability of the surrounding rocks.