盾构隧道下穿砖混建筑物群沉降控制案例分析

Case analysis on structure settlement control during construction of shieldedtunnel beneath brick masonry building group

呼和浩特市城市轨道交通2号线新华广场站至呼和浩特站盾构区间隧道侧穿砖混建筑物群。通过采用Midas GTS NX模拟分析了侧穿施工期间既有砖混建筑物结构的变形规律,具体提出了侧穿段区域洞内深孔注浆加固方案,并基于实测数据对地表及建筑物结构变形进行了分析,主要得到以下结论:地表沉降槽近似呈非对称"W"形,未采取注浆加固条件下建筑物沉降最大值为28.59 mm,且有向盾构中心线方向倾斜的风险;通过采用洞内深孔注浆加固措施,在拱顶120°范围形成深度3 m的注浆加固圈,能够基本满足地表及建筑物变形控制标准;盾构隧道侧穿施工期间,既有建筑物结构最大的隆起变形为3.39 mm,建筑物沉降值基本控制在10 mm,保证了既有砖混建筑物的安全。

The interval shielded-tunnel section of Hohhot Metro Line 2 from Xinhua Square Station to Hohhot Station laterally crosses a brick masonry building group.The deformation law of the existing brick masonry building structure during the construction of the lateral crossing section is simulatively analyzed by means of Midas GTS NX,and then the scheme of deep-hole grouting reinforcement inside the tunnel within the lateral crossing section is specifically proposed herein,while the deformations of both the ground surface and the building structure are analyzed according to the relevant measured data;from which it is concluded that the surface settlement trough approximately exhibits a asymmetric shape of“W”,while the maximum settlement of the building is 28.59 mm under the condition without grouting reinforcement and a risk of inclination toward the centerline of the shielded tunnel section is there.Through the deep-hole grouting reinforcement measure made inside the tunnel section,a grouted reinforced-circle with the depth of 3 m is formed in the range of 120°at the vault,and then the deformation control criteria for the ground surface and the building are basically satisfied.During the construction of the lateral crossing section of the shielded tunnel,the maximum uplifting deformation is 3.39 mm and the settlement is basically control at 10 mm for the existing building structure,thus the safety of the existing building is guaranteed.