In order to study the influence of foundation pit excavation on the vertical displacement of the vault of the underlying tunnel under different control measures, based on the Erqi Square Tunnel Project in Zhengzhou City, on the basis of verifying the reliability of numerical calculation, the finite difference software MIDAS GTS was used to analyze the deformation law of the vertical displacement of the tunnel vault under the two measures of stratum reinforcement and back pressure. The orthogonal test method was used to study the influence of reinforcement width, reinforcement depth, back pressure width and back pressure load on the vertical displacement of the tunnel vault. The results show that in similar projects, with the increase of the width and depth of the bottom reinforcement of the upper foundation pit, the vertical displacement of the vault of the underlying subway shield tunnel decreases nonlinearly, and the width coefficient i of the longitudinal deformation curve fitting function increases nonlinearly. With the increase of back pressure load and back pressure range, the vertical displacement of the vault of the underlying subway shield tunnel decreases linearly. The influence of the reinforcement depth of the pit bottom on the underlying subway shield tunnel is in turn greater than the back pressure load, the reinforcement width and the back pressure width. In the design of pit bottom reinforcement, it is recommended that the reinforcement width and reinforcement depth are easily set to 0.3 times and 0.4 times of the excavation depth of the foundation pit. In the comprehensive design of bottom reinforcement and back pressure surcharge, considering the deformation control effect, construction process and construction cost, among the 16 schemes of orthogonal test, scheme 4 and scheme 15 have the best control effect. The construction cost of scheme 4 is lower than that of scheme 15, and the deformation control effect of scheme 15 is better than that of scheme 4. The above suggestions can provide design basis for similar projects under silty clay or silty soil layer conditions.
Tian Shuai
,
Li Haoqiang
,
Lin Yunhong
,
Li Mingyu
,
Cao Guoxu
. Analysis of Back Pressure Reinforcement of Underground Passage Excavation on the Deformation of Subway Shield Tunnel[J]. Chinese Journal of Underground Space and Engineering, 2024
, 20(S2)
: 924
-930
.
DOI: 10.20174/j.JUSE.2024.S2.48
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