隧道施工诱发的地层沉降会影响地上建筑设施的安全,为了研究不同埋深隧道盾构施工影响下砂土地层的变形规律,设计了由模型架和非接触监测系统组成的模型试验系统。利用该系统,以干砂为填料,通过使隧道产生沉降来模拟施工影响下的地层损失,进而得出不同埋深情况下地层的变形规律。试验结果表明:①随着隧道埋深的增大,地层内部产生“土拱效应”,地表最大沉降值逐渐减小,地表沉降模式由“窄而深”演化为 “宽而浅”,但地层受扰动范围自隧道中轴线向两侧逐渐扩大;②不同埋深情况下,地表和地层内部的沉降曲线均符合高斯分布函数。地表沉降槽宽度系数随隧道埋深的增大而增大,深层土体沉降槽宽度系数随地层深度增加而减小;③不仅对于黏土,在砂土中深层土体沉降槽宽度系数iz与地表沉降槽宽度系数is之比iz/is同该土层深度hz与隧道埋深h的关系(1－hz/h)之间同样呈线性关系。因此,在浅埋的砂性及黏土地层中根据地表沉降规律即可得出地层内部沉降规律,从而为隧道的施工和支护结构的设计提供参考和指导。
Abstract
Ground settlement induced by tunnelling can affect the safety of ground building facilities. To study the deformation law of sandy soil strata under the influence of tunnelling at different burial depths, a model test system consisting of a model frame and a non-contact monitoring system was designed. Using this system, the stratum loss under the influence of tunnelling was simulated with dry sand as the filler. The deformation law at different depths of the stratum was then derived. Results elucidate that i) as the tunnel depth increases, the soil arching effect occurs within the stratum, the maximum settlement of ground gradually decreases and the surface settlement evolves from being narrow and deep to wide and shallow. However, the disturbed area of the ground gradually expands from the central axis of the tunnel to both sides. ii) At any buried depth, the settlement curves of the surface and within the strata all conformed to Gaussian distribution. The width coefficient of surface settlement trough increases with the increase of burial depth of tunnel, while that of deep soil decreases with the increase of depth. iii) For both clayey soil and sandy soil, the ratio of the width coefficient of deep soil settlement trough (iz) to that of surface settlement trough (is) is linearly dependent with the relationship (1-hz/h) between soil depth and tunnel's burial depth. Therefore, the law of settlement inside the stratum can be derived from the law of surface settlement in shallow buried sandy and clayey strata, thus providing reference and guidance for tunnel construction and support structure design.
关键词
隧道工程 /
地层沉降 /
模型试验 /
PIV技术 /
沉降槽
Key words
tunnel engineering /
surface settlement /
model test /
PIV technology /
settlement trough
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基金
国家自然科学基金项目(52168048);国家自然科学基金优青培育项目(20202ZDB01001)
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