盾构下穿既有房屋建筑安全状态评价与控制措施研究

王善刚

摘 要

近些年随着城市的快速发展，地铁隧道修建可用空间不断被压缩，因此不可避免会出现盾构下穿房屋建筑施工的情况，不仅加大了地铁建设难度，更是对房屋建筑的结构安全产生影响。由于不同建筑抵抗外界扰动影响的能力不同，同一建筑在不同的外界扰动影响下受损程度也将存在差异，当风险评估结果偏高时会使采取的措施过于保守，导致成本的增加；当评估结果偏低时会使采取的措施不足以规避项目风险，造成工程质量安全事故。因此本文依托武汉地铁安全预警项目实际工程，从既有房屋建筑安全状态和盾构下穿施工扰动影响程度两个方面分别进行安全评价，再将二者进行耦合以确定项目的综合安全状态，并制定控制措施，本文的研究内容如下。

（1）基于盾构施工扰动机理、地层变化对既有建筑影响以及房屋建筑抗变形能力对地层变形的约束作用，总结出了隧道—土体—建筑相互作用机理。

（2）基于实际工程项目，通过文献综合、实地调研和专家访谈法，建立了五里粮库和交警大队两栋建筑的原始安全状态评价指标体系；基于理论分析、案例分析和故障树理论，建立了盾构下穿施工过程安全状态评价指标体系。

（3）提出了基于熵权法和云模型的安全评价模型，使用模糊贴近度算法对评价云隶属的安全等级进行了准确计算。

（4）利用安全评价模型对两个项目的安全状态进行了详细分析，并确定了不同指标、既有房屋建筑、盾构下穿施工过程以及工程项目整体的安全状态，然后结合指标安全状态和其权重值来制定精准有效的控制措施。

关键词：盾构下穿房屋建筑；安全评价；综合安全状态；安全评价指标体系；云模型

Abstract

In recent years, with the rapid development of the city, the available space for subway tunnel construction has been continuously compressed, so it is inevitable that the shield tunnel will be constructed under the existing buildings, which not only increases the difficulty of subway construction, but also affects the structural safety of buildings. Due to different buildings have different ability to resist the influence of external disturbance, the damage degree of the same building under the influence of different external disturbance will also be different. When the risk assessment result is too large, the measures taken will be too conservative, resulting in an increase in cost; when the risk assessment result is too small, the measures taken will be insufficient to avoid the risk of the project, resulting in the occurrence of engineering quality and safety accidents. So this paper relies on the actual engineering of the Wuhan Metro Safety Early Warning Project to evaluate the safety of the existing buildings and the impact of the shield tunnel construction disturbance, and then couple them to determine the comprehensive safety state of the project and formulate control measures. The research contents of this paper are as follows.

(1) Based on the disturbance mechanism of shield construction, the influence of stratum change on existing buildings and the restraint effect of building anti deformation ability on stratum deformation, this paper summarizes the tunnel-soil-building interaction mechanism.

(2) Based on the actual project, the methods of literature synthesis, field investigation and expert interview are used to establish the original safety state evaluation index system of the two buildings of Wuli Grain Depot and Traffic Police Brigade; and theoretical analysis, case analysis and fault tree theory are used to establish the safety state evaluation index system of shield tunneling through two buildings is established.

(3) A security evaluation model based on entropy weight method and cloud model is proposed. The fuzzy proximity algorithm is used to accurately calculate the security level of the evaluation cloud.

(4) The safety evaluation model is used to analyze the safety status of the two projects in detail, and determine the different indicators, the existing housing construction, the shield tunneling construction process and the overall safety status of the project, and then formulate accurate and effective control measures in combination with the indicator safety status and its weight value.

Key words: shield tunneling through buildings; safety evaluation; comprehensive safety status; safety evaluation index system; cloud model