盾构下穿桥梁桩基地层参数优化反演研究与应用

Research and application of optimization inversion of pile foundation parameters for shield tunneling under bridge foundation

摘要

复杂地质条件下盾构下穿桥梁桩基施工时，地层关键参数的准确测定对于施工安全至关重要。已有方法存在环境扰动大、现场参数难以获取以及测定效率低、精度不足等局限性，针对这一问题，依托广州地铁12号线东湖岛—二沙桥段区间双线盾构隧道下穿桥梁桩基实际工程，提出了一种基于登山队优化算法(MTBO)的无损反演地层参数的智能优化方法。该方法采用FLAC^3D数值模拟软件计算盾构下穿施工过程中的地表沉降，将模拟计算结果与实际监测得到的地表沉降数据进行对比，以对比误差构建MTBO算法中的目标函数。通过将地层参数设为优化变量，利用MTBO算法的高效全局计算能力，对目标函数进行迭代优化，直至找到使误差最小化的地层参数值，并将该方法成功应用于工程实例。结果表明，该智能优化方法在计算效率和计算精度上都有较大优势，能为复杂的岩体优化反演问题提供帮助；对于地质构造复杂的广州轨道交通12号线，在盾构隧道下穿桥梁桩基后，该方法反演出的弹性模量、黏聚力和内摩擦角值等关键地层参数与真实值较为接近，相对误差均小于14%,说明了该方法的工程适用性；该方法在工程实例中的计算耗时为22 197 s,极大缩减了工作耗时。

Abstract

Accurate determination of key geological parameters is crucial for construction safety during shield tunneling of bridge pile foundations under complex geological conditions. Existing method have limitations such as large environmental disturbances, difficulty in obtaining on-site parameters, low measurement efficiency, and insufficient accuracy. In response to this problem, an intelligent optimization method based on the Mountaineering Team Optimization Algorithm(MTBO) for non-destructive inversion of geological parameters is proposed, relying on the actual engineering of the bridge pile foundation under the double line shield tunnel in the Donghu Island Ersha Bridge section of Guangzhou Metro Line 12. This method uses FLAC^3D numerical simulation software to calculate the surface settlement during shield tunneling construction. The simulation result are compared with the actual monitored surface settlement data to construct the objective function in the MTBO algorithm based on the comparison error. By setting geological parameters as optimization variables and utilizing the efficient global computing power of the MTBO algorithm, the objective function is iteratively optimized until the geological parameter value that minimizes the error is found. The method is successfully applied to engineering examples, and the result show that this intelligent optimization method has significant advantages in computational efficiency and accuracy, and can provide assistance for complex rock optimization inversion problems; For the complex geological structure of Guangzhou Metro Line 12, after passing through the bridge pile foundation under the shield tunnel, the key geological parameters such as elastic modulus, cohesive force, and internal friction angle obtained by this method are relatively close to the actual values, with relative errors less than 14%, indicating the engineering applicability of this method; The calculation time of this method in engineering examples is 22197 s, greatly reducing the work time.

关键词

盾构隧道 / 桥梁桩基 / 参数反演 / 登山队优化

Key words

shield tunnel / bridge pile foundation / parameter back analysis / mountaineering team-based optimization