泥炭质土层盾构施工扰动引起隧道长期沉降的研究

发布时间：2018-01-14 03:24

本文关键词：泥炭质土层盾构施工扰动引起隧道长期沉降的研究　出处：《岩土工程学报》2017年08期 　论文类型：期刊论文

【摘要】：为了研究泥炭质土层盾构施工扰动引起隧道的长期沉降问题,将隧道周围土体视为连续、均质、各向同性的饱和黏弹性介质,采用五元件模型描述泥炭质土的流变特性,耦合Terzaghi-Rendulic二维固结理论,建立了隧道衬砌在完全不透水的情况下,盾构施工扰动引起周围土体超孔隙水压力消散的控制方程。采用分离变量法、保角映射、Laplace变换及逆变换等数学方法对该控制方程进行求解,得到了隧道周围土体超孔隙水压力消散的解析解,最后对土体的竖向应变进行积分获得了隧道长期沉降的计算公式。结合一工程算例分析了昆明泥炭质土层超孔隙水压力消散及隧道长期沉降的变化规律,研究结果表明:与上海软黏土相比,在初始阶段泥炭质土层中超孔隙水压力的消散速度较快,然后迅速变缓并趋于稳定。泥炭质土层中隧道的长期沉降持续时间更长且沉降量更大,在900 d的时间内隧道沉降趋于稳定,其累积沉降量约高达150 mm。此外,昆明泥炭质土的流变特性显著,如将土体中超孔隙水压力消散90%作为主固结沉降的完成时刻,则土体次固结沉降约占隧道总沉降量的36%,是隧道长期沉降中不可忽视的一个重要组成部分。
[Abstract]:In order to study the long-term settlement of the tunnel caused by the disturbance of peat shield construction, the soil around the tunnel is regarded as a continuous, homogeneous and isotropic saturated viscoelastic medium. A five-element model is used to describe the rheological characteristics of peat soil. Coupled with Terzaghi-Rendulic 's two-dimensional consolidation theory, tunnel lining is established under the condition of complete impermeability. The governing equation of excess pore water pressure dissipation caused by shield tunneling disturbance is solved by using the method of separating variables, conformal mapping Laplace transform and inverse transformation. The analytical solution of excess pore water pressure dissipation around the tunnel is obtained. Finally, the calculation formula of tunnel long-term settlement is obtained by integrating the vertical strain of soil. Combined with an engineering example, the variation law of excess pore water pressure dissipation in Kunming peat soil layer and tunnel long-term settlement is analyzed. The results show that the dissipation rate of excess pore water pressure in peat soil is faster than that in Shanghai soft clay. The long-term settlement of the tunnel in peat soil is longer and the settlement is larger, and the tunnel settlement tends to be stable in 900 days. The cumulative settlement is about 150mm. in addition, the rheological characteristics of Kunming peat soil are remarkable, such as the dissipation of 90% excess pore water pressure in the soil as the completion time of the main consolidation settlement. The secondary consolidation settlement of soil accounts for about 36% of the total settlement of the tunnel, which is an important part of the long-term settlement of the tunnel.
【作者单位】：昆明理工大学建筑工程学院;
【基金】：国家自然科学基金项目(51408284,U1502231,51508253)
【分类号】：U455.43;U456.3
【正文快照】： 盾构法具有施工速度快、自动化程度高、对周边环境影响小等特点,是修建城市隧道的优选工法之一,已在世界各国地下工程中得到广泛应用。虽然盾构施工技术日臻完善,但仍不可避免地会对周围地层产生扰动,从而引起隧道及周围土体的长期沉降,尤其是当隧道处于软弱、高含水率、高压

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