盾构隧道掘进对砌体结构建筑物沉降的影响

Shield Tunnel Construction Induced Influence on the Settlement of Masonry Buildings

结合杭州地铁1号线某区间隧道工程下穿13栋住宅群的盾构施工,通过右线隧道(先掘进)和左线隧道(后掘进)下穿建筑物整个施工期间的建筑物底部与屋顶沉降的监测及分析,研究盾构隧道掘进施工对地表砌体结构建筑物沉降的影响规律。结果表明:砌体结构建筑物的沉降历时规律有别于天然地表沉降,尤其是后续沉降阶段的下沉量占累积沉降量的比例明显大于天然地表;右线施工稳定之后,砌体结构建筑物底部与屋顶的沉降曲线均基本符合高斯正态分布,左线通过后不再符合高斯分布规律;砌体结构建筑物屋顶的沉降曲线均与其邻近立面底部沉降曲线较为接近;单线隧道施工时,砌体结构建筑物的沉降曲线可用地表沉降Peck公式表达,但两者存在着本质差别,杭州地区砌体结构建筑物沉降槽的地层损失率取值范围一般为0.7%～6.4%,平均值为1.98%,沉降槽宽度参数的取值范围一般为0.36～1.77,平均值为0.78。

Combined with the shield construction of a certain section tunnel engineering of Hangzhou Metro Line 1 cross under 13 residence buildings,through monitoring and analyzing the settlements of the bottom and roof of building during the whole construction period of right-line tunnel(earlier launching) and left-line tunnel(later launching) cross under building,the influence laws of shield tunnel construction on the settlements of surface masonry building were analyzed.Results show that the time-history curves of masonry building settlement are different from that of green field settlement.Especially,the proportion of the subsequent subsidence in cumulative settlement is significantly greater than the case of green field.The settlement curves of the building bottom and roof are approximately in agreement with Gaussian distribution after right-line tunnel passing,and they no longer match with Gaussian distribution after left-line tunnel passing.The settlement curves of masonry building roof are all closer to those of its adjacent facade bottom.The settlement curves of masonry building can be expressed by Peck formula for ground settlement during single line tunnel construction.However,there is an essential difference between them.The stratum loss ratios of the settlement troughs for masonry buildings in Hangzhou area range generally from 0.7% to 6.4%,and the average is 1.98%.The value range for the width parameters of settlement troughs is generally from 0.36 to 1.77,and the average is 0.78.