盾构隧道施工阶段管片局部开裂原因初探

STUDY ON LOCAL CRACKING OF SEGMENTS IN SHIELD TUNNEL DURING CONSTRUCTION

钢筋混凝土管片作为盾构隧道最基本的结构单元,其破损和开裂必将造成隧道质量问题,并最终影响隧道的使用寿命。在施工过程中,发现部分管片螺栓孔附近出现开裂或破损,为分析出现裂缝或破损的原因,首先,通过3对标准块管片足尺正、负弯曲试验,发现并没有出现上述裂缝,从现象上证明该开裂不是由于管片间相对弯曲位移产生的;然后,通过三维有限元模拟,分别计算1对标准块管片在相对弯曲和相对扭转时的应力分布,通过分析应力云图和截面应力等值线发现,施工过程中出现的开裂和破损是由管片间相对扭转引起的。

Reinforced concrete segments are the basic structure units in shield tunnel. The cracking and breakage on segments will cause quality defect, and finally influence the durability of shield tunnel. During construction, crack appears on some segments near the bolt holes. In order to find out the reasons, first, full-scale positive and negative bending tests are applied to three pairs of standard segments. The tests indicate that the bending displacement do not cause these cracks. Afterwards, the finite element method is used to calculate the segments stress distribution under relative bending and torsional moments between two standard segments. The contours and cross-section stress curves of analytical results indicate that the relative torsion between segments causes the cracks during shield tunnel construction.