为探究砂土层中考虑新建类矩形盾构隧道施工过程中土体的损失和新建隧道与既有盾构隧道不同位置时，新建类矩形盾构隧道对既有隧道的围压、隧道拱底应变和拱顶位移的影响，采用室内模型试验的方法，进行新建类矩形隧道重叠下穿、夹穿和不同隧道间距下正交90°下穿的试验。研究结果表明： 1）各种工况下新建类矩形盾构隧道在夹穿既有隧道时对上线既有隧道的影响最大； 2）夹穿工况下，新建类矩形盾构隧道开挖到既有隧道下方时，上线既有隧道拱底围压发生突变且数值极大； 3）隧道的间距是新建类矩形盾构隧道施工时引起既有盾构隧道围压、拱底应变、拱顶位移等发生改变的重要影响因素，实际施工时应尽可能保持新建隧道与原有盾构隧道的间距足够大； 4）新建类矩形盾构隧道下穿既有隧道过程中，既有隧道拱顶存在快速变形的阶段，在实际工程中需要重视这一过程中对隧道拱顶变形速率的控制。
赵得乾麟
,
魏纲
,
梁禄钜
,
姜海波
,
项鹏飞
,
木志远
. Experimental Study on Responses of Existing Tunnels to Adjacent QuasiRectangular Shield Tunneling in Sandy Soil（砂土层中类矩形盾构施工对邻近既有隧道造成影响的模型试验研究）[J]. 隧道建设, 2024
, 44(5)
: 1000
-1011
.
DOI: 10.3973/j.issn.2096-4498.2024.05.009
Indoor modeling experiments are conducted to
investigate the influence of quasirectangular shield tunneling
on the confining pressure and deformation of adjacent existing tunnels in sandy
soils. In this study, ground loss during 〖HJ3.8mm〗the construction as well as the relative positions of the new and
existing tunnels are investigated. Different construction conditions, including
overlapping underpass, pinch underpass, and orthogonal underpass with varying
tunnel spacings are assessed. Results indicate that: first, among various
construction conditions, the new quasirectangular
shield tunnel has the most significant impact on the existing tunnel when it
passes through in a constrained manner. Under this condition, quasirectangular shield tunneling beneath the existing tunnel leads to a
sudden and notably remarkable change in the confining pressure at the bottom of
the tunnel′s arch. Then, the spacing between tunnels
remarkably affects the confining pressure, the strain at the arch bottom of the
existing tunnel, and the displacement at the crown of the existing tunnel
during the new quasirectangular shield tunneling.
Therefore, a sufficiently safe distance between the new and existing tunnels
must be maintained. Finally, the deformation of the existing tunnel crown is
sharply increased in a certain stage during the new quasirectangular shield tunneling underneath. In actual engineering,
considerable attention must be provided to control the deformation rate in this
stage.
