顶管施工中设置合理的泥水压力是保证开挖面稳定的关键,泥水压力过小会导致地表沉降,严重时发生主动失稳;泥水压力过大会引起地表隆起,严重时发生被动失稳,影响施工及周围构筑物的安全。以西南地区某给水顶管隧道工程为背景,理论推导出黏土地层顶管施工开挖面被动极限支护压力的上限解,对比分析被动支护压力上限解与现场泥水压力的关系,并进一步研究不同埋深、内径对被动支护压力的影响。结果表明:(1)对比本文被动支护压力上限解与现场泥水压力,得到理论解值高于实测泥水压力;(2)随着埋深的增大,被动支护压力呈线性增大,其压力比呈抛物线形增大,增大速率逐渐减小,埋深2 m增大至10 m时,被动支护压力和压力比分别增大456.6%和59.1%;(3)随着内径的增大,被动支护压力呈抛物线形增大,增大速率逐渐减小,内径2.0 m增大至3.2 m时,被动支护压力增大5.6%。本研究可为类似工程中泥水压力的合理设定提供一定参考。
Setting reasonable slurry pressure in pipe jacking construction is the key to ensuring the stability of excavation face. If the slurry pressure is too small, it will lead to surface subsidence, and active instability will occur in severe cases. Excessive mud pressure will cause surface uplift and passive instability in severe cases, which will affect the safety of construction and surrounding structures. Based on the background of a water supply pipe jacking tunnel project in southwest China, the upper bound solution of passive limit support pressure of excavation face in clay stratum is derived theoretically, and the relationship between the upper bound solution of passive support pressure and the field slurry pressure is compared and analyzed. The influence of different buried depth and inner diameter on the passive support pressure was further studied. The results show that: (1) By comparing the upper limit solution of passive support pressure with the field mud pressure, the theoretical solution value is higher than the measured mud pressure, which can provide some reference for the reasonable setting of mud pressure in similar projects. (2) With the increase of buried depth, the passive support pressure increases linearly, the pressure ratio increases parabolically, and the increase rate decreases gradually. When the buried depth increases from 2 m to 10 m, the passive support pressure and pressure ratio increase by 456.6% and 59.1% respectively. (3) With the increase of inner diameter, the passive support pressure increases parabolically, and the increase rate decreases gradually. When the inner diameter increases from 2.0 m to 3.2 m, the passive support pressure increases by 5.6%.
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