软黏土地层顶管隧道掌子面稳定性数值研究

发布时间：2018-08-22 08:48

【摘要】：土压平衡式顶管施工中顶进支护压力是维持前部掌子面稳定的重要施工控制参数。在软黏土地层中考虑分段顶进和开挖土体受扰动强度折减,采用数值模拟分析顶进掌子面支护压力不足引起的前部土体主动破坏模式、塑性区发展、地层扰动以及土体应力释放,在此基础上进一步研究顶管隧道埋深、管径、土层性质和不同扰动强度折减等因素对极限顶进支护压力的影响规律。结果表明:(1)当掌子面顶进支护压力逐步减小时,前部土体呈现半梨形外鼓破坏模式;塑性区在一定范围内发展近似形成半椭球形;掌子面应力释放率逐步增大,但不同部位处的应力释放率存在差异,掌子面中心处应力释放率大于顶部和底部;(2)主动极限顶进支护压力随着埋深和管径增大而不同程度地增大;土层性质参数对极限顶进支护压力影响的敏感程度依次为内摩擦角、粘聚力和弹性模量,其中内摩擦角和粘聚力受扰动折减程度对极限顶进支护压力有较为显著的影响,弹性模量扰动折减则几乎无影响。
[Abstract]:In the soil pressure balanced pipe jacking construction, the jacking support pressure is an important construction control parameter to maintain the stability of the front face. In the soft clay formation, the active failure mode of the front soil caused by insufficient supporting pressure on the jacking face is analyzed by numerical simulation, and the plastic zone is developed, considering the segmented jacking and the disturbed strength reduction of the excavated soil. On the basis of ground disturbance and soil stress release, the influences of the buried depth, pipe diameter, soil properties and different disturbance intensity on the ultimate jacking support pressure are further studied. The results are as follows: (1) when the pressure of jacking support on the face of the face decreases gradually, the front soil presents the failure mode of semi-pear-shaped outburst, the plastic zone develops approximately into a semi-ellipsoid shape within a certain range, and the stress release rate of the face of the palm increases gradually. However, the stress release rates at different positions are different, and the stress release rate at the center of the palm is greater than that at the top and bottom. (2) the pressure of the active limit jacking support increases in varying degrees with the increase of the buried depth and the diameter of the pipe. The sensitivity of soil property parameters to the pressure of ultimate jacking support is in the order of internal friction angle, cohesion and elastic modulus, in which the angle of internal friction and the degree of reduction of cohesion by disturbance have a significant effect on the pressure of ultimate jacking support. The disturbance reduction of elastic modulus has little effect.
【作者单位】：北京工业大学建筑工程学院;
【基金】：国家自然科学基金重点项目(51538001) 国家973项目(2014CB047100)
【分类号】：U451

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