长距离顶管下穿复杂地质、地形条件时面临顶进困难、泥浆护壁形成困难以及地层扰动大等挑战。为研究长距离矩形顶管的掘进参数影响，依托某矩形顶管下穿京杭运河顶管工程，对长距离顶管顶进力学行为以及顶管施工对周边环境影响规律进行分析。基于现场试验得到的管浆摩擦因数，采用土柱理论计算管周摩阻力进而得到不同顶进距离下的顶管顶力；基于现场监测数据，分析长距离顶管下穿运河时顶力、顶进速度以及顶进参数（送泥压力、注浆压力、泥舱压力）的变化规律，总结双线顶管施工条件下地表沉降变化规律。结果表明： 1）采用泥浆润滑理论计算顶力可降低约40%，更接近实际值，通过泥浆润滑理论调整摩擦因数提高计算准确性； 2）顶管穿越不同地层的过程中，地层性质差异和较大顶管偏转角会导致顶力显著变化； 3）在高水压环境下，应根据地层的埋深和水压力，合理调整注浆压力，通过精确控制这些参数，可以更有效地维持掌子面及周围土体的稳定，减少地层扰动，防止地表竖向位移过大，抵御顶进面突水和涌水灾害的风险。
Long-distance pipe jacking through complex geological strata faces the
challenges of difficult jacking, difficult mud wall formation, and excessive
ground disturbance. To address these issues, a case study is conducted on a
long-distance rectangular pipe jacking project crossing
underneath Beijing-Hangzhou Grand Canal, and the
mechanical behavior of long-distance pipe jacking and
the influence of pipe jacking on surrounding environment are systematically
examined. Based on the friction coefficient of slurry obtained from field test,
the peripheral friction resistance of the pipe is calculated using soil column
theory, thus obtaining the pipe jacking force at different jacking distances.
The varying process of jacking force, speed, and parameters (slurry feeding
pressure, grouting pressure, and slurry chamber pressure) in response to long-distance pipe jacking underneath river is analyzed, and the surface
settlement pattern under double-line pipe jacking
condition is summarized. Some conclusions are drawn as follows: (1) The pipe
jacking force calculated by slurry lubrication theory is reduced by
approximately 40%, which is closer to actual values. The slurry lubrication
theory improves the calculation accuracy by adjusting friction coefficient. (2)
When jacking in different strata, the difference in the properties of the
strata and the large pipe jacking deflection angle lead to significant change
in jacking force. (3) Under high water pressure condition, controlling the
grouting pressure according to burial depth and water pressure effectively
guarantees stable working face and surrounding soil, minimizes ground
disturbance, thus avoiding excessive vertical surface displacement and water
gushing disaster.
