﻿ 洞桩法暗挖车站施工过程对周边环境的影响分析

# 洞桩法暗挖车站施工过程对周边环境的影响分析Research on the Environmental Effects Caused by Metro Station Construction with Pile-Beam-Arch Method

Abstract: The construction of subway station will inevitably disturb surrounding ground, which may cause excessive settlement or differential settlement of existing buildings within a certain range. Due to this, the normal use and safety of adjacent buildings will be affected. In this paper, a history case about an underground excavation subway station with difficult construction processes and high risk was studied. For the key problems during construction, the space effect and differential settlement of adjacent building were analyzed using numerical simulation method, and the effect of construction with PBA method on adjacent buildings was discussed. The crucial risk control measures were proposed.

1. 引言

2. 工程概况

Figure 1. Construction section of Taiyuan Street Station

3. 施工过程数值模拟分析

3.1. 计算模型及边界条件

Figure 2. Numerical calculation model

1) 首先施加自重荷载进行初始地应力计算，并对模型计算结果位移进行清零。

2) 根据图1所示PBA施工工序，一次施作边导洞、中导洞、两侧围护桩，并结合工序图分步开挖，模型中每次开挖循环长度为10 m。

3) 结合施工工序图，依次拆除临时支护结构体系，拆撑步长为5 m。

4) 施作主体结构二次衬砌。

Table 1. Formation mechanics parameters

3.2. 计算结果分析

PBA暗挖车站施工结束时地表沉降云图及地面最大沉降点随开挖步骤变化曲线详见图3图4。结

Figure 3. Vertical displacement cloud map

Figure 4. Settlement history curve of the center point of the ground surface

Figure 5. Post-construction deformation cloud map of New World Phase I

Figure 6. Horizontal deformation cloud diagram of side piles

Figure 7. Settlement and slope history curve of the first phase of the New World

Figure 8. Post-construction deformation cloud map of New World

Figure 9. Settlement and slope history curve of the second phase of the New World

4. 结论

1) 洞桩法在城市复杂环境下适用于建设暗挖地铁车站，建设过程对周边环境的影响基本在可控范围以内。

2) 对于采用PBA工法建造的地铁暗挖车站，地层移动及沉降等风险较大阶段主要发生在导洞开挖及扣拱施工阶段，应在该阶段采取地层超前加固、既有建筑物沉降监测频率加大等风险控制措施，保证工程自身及周边环境的安全。

3) 由于两侧围护桩的隔离作用，洞桩法开挖车站地面沉降槽主要位于上导洞影响范围，对周边环境的影响有限，适用于复杂环境下地铁暗挖车站的建造。

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