既有地铁注浆抬升合理位置的确定

Determination of proper position of grouting during lifting the existing subway

由于施工的扰动,新建地铁穿越既有地铁时,会对既有地铁产生影响。当影响达到一定程度时,除了影响结构的使用安全外,甚至会威胁列车的运营安全性。为了提高工程的安全性或者减小施工的难度,通常在施工过程中或者工后对既有地铁进行注浆抬升,恢复其高程与差异沉降。但是注浆抬升会使既有结构产生应力集中,这对既有结构不利。针对既有结构的注浆抬升建立模型进行分析,提出在弱化位置注浆的理念。模型计算结果说明弱化位置注浆减小了沉降的同时,产生一定的应力集中。对北京地铁5号线崇文门穿越工程中既有地铁实际注浆情况进行分析,注浆方案减小了沉降,但也产生了比较大的应力集中。监测数据表明,注浆抬升效果显著,提高了既有地铁的安全性。

Because of the construction disturbance, the existing subway would be influenced when a new subway was built near it. When the influence reached a certain degree, the operating security of the existing subway would be threatened. For increasing the project security or decreasing the construction difficulty, lifting the existing subway by grouting was used in general to recover its elevation and to decrease differential settlement during or after the construction. The model of lifting the existing subway by grouting was created and the concept of grouting in the weak position was put forward. It was indicated that grouting in the week position would decrease the settlement and induce little stress concentration. The practical grouting program of the existing Beijing subway line 5 in the Chongwenmen station was analyzed. It was indicated that the settlement was decreased by grouting, but the degree of the stress concentration was some how large. Therefore, the lifting effect was significant and the safety of the existing subway in operation was increased.