真实复杂地层大直径钢顶管三维数值模拟研究

为了揭示地表沉降与管周土体扰动沿顶进方向的真实变化规律，本文提出了真实复杂地层三维数值建模方法。依托某市北线引水工程隐患整改顶管工程项目，采用FLAC3D分析平台开展了真实复杂地层和简化均匀地层条件下的大直径钢顶管施工数值模拟研究。模拟结果及现场地表沉降实测结果对比表明：基于真实复杂地层模型的模拟结果与现场沉降监测结果吻合较好，能够准确反映地表沉降沿纵向的变化规律，而简化地层模型模拟结果与监测值差距较大。扰动分析表明顶管施工时会引起其上方地层的沉降变形和下方地层的抬升变形，其变形值大小与地层土体性质和分布有关。顶管上覆土体横向位移基本朝向顶管轴线，其变形受土体空间分布的影响较小，但顶管下部土体的横向变形受土体空间变化影响较大。地表沉降的横向影响范围为?5.3D（D为顶管直径），且受土层分布影响较小，但地表沉降值受地层分布影响较大。

Three-dimensional Numerical Simulation of Large-diameter Steel Pipe Jacking in Real and Complex Strata

Reveal the characteristic of surface settlement and soil deformation during the pipe-jacking under real strata, a modeling method of real and complex strata was proposed in this study. Based on a diversion project in a city, this paper conducted the three-dimensional numerical simulation of pipe-jacking construction in real complex strata and simplified strata. The simulated results of surface settlement in the real and complex strata agree very well with the field measurement results, while the settlement obtained from the simulation in simplified and uniform strata disagreed with the settlement from in-situ measurement. The simulated displacement of soil above the pipe goes down and the displacement below the pipe goes down, of which the value was related to the mechanical behavior and geometric distribution of strata. The lateral displacement of soil above the pipe is basically oriented toward the pipe jacking axis, and the spatial distribution of soil has no effect on the value. However, the spatial distribution of soil significantly effects the lateral deformation of soil below the pipe jacking. The complex strata significantly influence the value of surface settlement. However, the lateral range of surface settlement is ±5.3D (D the pipe diameter), and is significantly influenced by the distribution of complex strata.