摘 要

新建基坑的开挖通常位于城市中心，基坑工程的周边环境十分复杂，城市建筑空间有限，通常在起周围存在各种建筑物。这就要求基坑支护除满足强度要求外，还需满足变形要求，基坑的设计理念也由强度控制变为变形控制。而邻近地铁车站的存在会使基坑开挖的变形与邻近无地铁车站时时有所不同。因此本文通过64组有限元数值模拟，研究了不同参数即开挖深度H，基坑宽度L，地铁车站距离基坑位移D组合下邻近地铁车站的基坑变形性状，并与邻近无车站的情况作对比分析。研究结果表明：

（1）当邻近存在地铁车站时，靠近车站一侧的地下连续墙最大侧移量减小，另一侧的地下连续墙最大侧移量增加。

（2）地铁车站的存在与否并不明显改变基坑远离车站一侧地表沉降最大值，但邻近存在地铁车站会增加其靠近车站一侧的地表沉降最大值，在基坑的开挖深度H达到地铁车站底板埋深时影响最大。

（3）基坑宽度的增加会引起基坑两侧的地下连续墙最大侧移量的相应增加，其影响程度随着L的增大而增加；宽度L的增加引起基坑两侧地表最大沉降量的增大，但影响程度随着L的增大而减弱；开挖深度H的增加引起基坑坑底最大隆起值的增加，但增加幅度小于开挖深度H对其产生的影响。

（4）当地铁车站与新建基坑距离D较小时，随着H的增大，地铁车站的“遮拦效应”越来越显著。而当D逐渐增大时，H对地铁车站“遮拦效应”的影响逐渐减弱。

（5）地铁车站距离新建基坑的位移D的变化量不明显改变基坑两侧地下连续墙的最大侧移量，D越大时，基坑右侧地下连续墙最大侧移量略有减小，其左侧大于无地铁车站对应值，右侧小于无地铁车站的对应值；D的变化量不明显改变基坑左侧地表沉降最大值，但随着D的增加，其右侧地表沉降最大值相应减少。

关键词：基坑；地铁车站；变形性状；参数化分析

Investigation on deformation behaviors of foundation pit adjacent to existing metro stations

ABSTRACT

The excavation of the new foundation pit is usually located in the center of the city. The surrounding environment of the foundation pit is very complicated. The space of the urban building is limited, and there are all kinds of buildings in the surrounding area. This requires the foundation pit support in addition to meet the strength requirements, but also to meet the deformation requirements, the design of the pit design concept from the intensity control into deformation control. And the proximity of the subway station will make the excavation deformation of the pit and the adjacent subway station always different. In this paper, 64 sets of finite element plaxis numerical simulation are used to study the deformation behavior of foundation pit of adjacent subway station with different parameters such as excavation depth H, foundation pit width L, subway station distance foundation pit displacement D, and with adjacent station Situation for comparative analysis. The structure of the study shows that (1) when the adjacent subway station is located, the maximum lateral displacement of the underground continuous wall near the station side decreases and the maximum lateral displacement of the underground continuous wall increases; (2) the presence or absence of the subway station There is no obvious change in the foundation pit away from the station side of the surface settlement of the maximum, but adjacent to the existence of the subway station will increase its near the station side of the maximum settlement of the ground, in the excavation depth of the pit to reach the subway station floor depth (3) The increase of the width of the foundation pit will cause the corresponding increase of the maximum lateral displacement of the underground continuous wall on both sides of the foundation pit. The influence degree increases with the increase of L; the increase of the width of the foundation pit The increase of the maximum settlement value of the side surface is weakened, but the influence degree decreases with the increase of L. The increase of the excavation depth L increases the maximum uplift value of the foundation pit, but the increase is

less than the excavation depth H (4) When the distance between the subway station and the new foundation pit D is small, with the increase of H, the "blocking effect" of the subway station becomes more and more significant. And when D gradually increases, H on the subway station "blocking effect" effect gradually weakened. (5) The change of the displacement D of the subway station from the new foundation pit does not significantly change the maximum lateral displacement of the underground continuous wall on both sides of the foundation pit. When the D is bigger, the maximum lateral displacement of the underground continuous wall Small, the left side is greater than the corresponding value of the subway station, the right side is less than the corresponding value of the subway station; D changes do not significantly change the left side of the pit

And the maximum value of the subsidence on the right side of the right side decreases with the increase of D.

Key words: foundation pit; metro station; deformation behavior; parametric study

目 录

1 绪论 1

1.1研究背景及意义 1

1.2国内外研究现状 2

1.2.1基坑工程不同地区实例研究 2

1.2.2基坑变形性状受环境影响研究现状 3

1.2.3基坑变形性状受开挖方式影响研究现状 4

1.2.4土体变形引起基坑围护结构位移研究现状 6

1.2.5目前研究所存在的问题 7

1.3主要研究内容 8

2 基坑变形性状基本算例模拟数值分析 9

2.1基坑的变形理论 9

2.2有限元方法在基坑工程中的应用 10

2.3基坑模型的建立与参数的选取 11

2.3.1单元选择 11

2.3.2土层参数 11

2.3.3材料特性 11

2.3.4计算模型 12