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

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.

Keywords

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