盾构施工中注浆因素对地表沉降的影响研究

以天津地铁某区间工程为依托,采取现场监测和数值模拟相结合的方式,利用FLAC3D软件模拟盾构开挖动态过程,研究隧道开挖对地层变形的扰动规律,发现考虑注浆孔分布的非均匀注浆形式模拟最接近实际情况,通过数值模拟有效地模拟了现场实测结果,进而将结果推广,得到各种注浆参数对注浆效果的影响。数值模拟结果表明:一定范围内注浆压力越大土体沉降越小,当注浆压力大于一定值时(本例为0.2MPa,各地区情况不同),对地表沉降的影响不再明显;注浆不及时的地表沉降明显大于注浆及时的情况,同步注浆可以很大程度上减少土体的沉降值;在一定范围内增大注浆量可以有效地减少地面沉降,即地面沉降随盾尾空隙填充率的增加而减少。

Study on the Impact of the Grouting Factors on Surface Subsidence in the Process of Shield Construction

Based on a range of Tianjin Metro engineering, taking a combination of field monitoring and numerical simulation, using the FLAC3D software accurately to simulate the dynamic process of shield excavation, to research the disturbance law of ground deformation caused by tunnel excavation, it is found that the distribution of grouting hole non-uniform grouting form of simulation is more closed to the actual project, then, using numerical simulation to simulate the field test results, and thus promote the result extension, to get the influence of various grouting parameters on the grouting effect. The numerical simulation results show that: with a certain range the greater the grouting pressure is, the smaller the soil settlement will be, the decrease of surface settlement caused by the increase of grouting pressure is unconspicuous after the grouting pressure reachs to a certain value(0.2 MPa,each region is different); for grouting not timely, the surface settlement is significantly larger than that for the grouting timely situation, synchronously grouting can largely reduce the soil settlement value; increasing the quantity of grouting in a certain range can effectively reduce the ground settlement, namely, the surface settlement decreases with the shield tail void filling rate increasing.