竖向顶管施工全过程数值模拟研究

Numerical Simulation Study on Whole Construction Process of Vertical Pipe Jacking

  • 摘要: 为分析竖向顶管在管廊内向上顶升过程中对周围环境产生的影响,文章采用MIDAS GTS NX软件进行建模,通过改变所建模型的材料参数和激活、钝化相应网格的方法来模拟竖向顶管施工的实际过程,研究不同土质条件、不同施工参数、不同顶管管径、不同地下水位等因素造成的影响,并与设计的模型试验所得数据进行对比分析。结果表明:随着竖向顶管的顶进,在-1D~1D(D为竖向顶管直径)范围内地表土体先沉降后隆起,最大隆起值为4.13 mm;而管廊的沉降则是逐渐增加,最大可达3.44 mm;土质条件越差,土体及管廊因顶管向上顶进产生的扰动就越大,而地下水的存在使-1D~1D范围内地表隆起现象消失;不同施工参数对顶管施工造成的影响不同,正面推力对于顶管施工的影响不大,而摩擦系数的改变对于土体及管廊竖向位移影响较大;模型试验所测得的地表土体位移变化规律与数值模拟结果较为一致。

     

    Abstract: In order to analyze the impact of vertical pipe jacking on the surrounding environment during the pro? cess of upward jacking from the utility tunnel, this paper uses the Midas GTS NX software to establish the model and simulate the vertical pipe jacking construction process by changing the material parameters of the model as well as activating and passivating the corresponding mesh. And then the effects on pipe jacking induced by different soil conditions, construction parameters, pipe diameters and groundwater depths are studied and compared with the model test data. The results show that the surface soils first settle and then heave in the range of -1D~1D (D is the diameter of vertical jacking pipe) along with the vertical pipe jacking, and the maximum heaving value is 4.13 mm; the utility tunnel settlement increases gradually and is up to 3.44 mm at most; the worse the soil condition, the greater the disturbance to the soils and utility tunnel due to the upward jacking, and the existence of groundwater makes the surface heaving phenomenon disappear in the range of -1D~1D; different construction parameters have different effects on pipe jacking, the change of front thrust and pipe diameter has a little effect on pipe jacking, while the change of friction coefficient has a great effect on vertical displacements of soils and utility tunnel; the variation law of surface soil displacement measured by the model test is consistent with the numerical simulation results.

     

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