Bosong Ding

Shield tunneling in urban areas can generate ground vibrations that may threaten adjacent buildings, especially in hard rock strata. However, the effect of foundation type on the vibration response of multi-story buildings is not yet fully understood. This study investigates this issue through a combined approach of field monitoring and three-dimensional numerical simulation based on the Jinan Metro Line 4 project. Five-story frame buildings with pile, raft, and isolated footing foundations were analyzed, and the numerical model was validated against measured data to ensure reliability. The results show that vibration waves attenuate in an approximately symmetric elliptical pattern and are amplified by the presence of buildings. A significant vertical amplification effect is observed, with peak particle velocity at the top floor reaching up to 2.11 times that at the ground surface. Foundation type exerts a significant influence on vibration transmission. Raft foundations exhibit a more uniform vibration distribution, whereas isolated footings demonstrate a weaker attenuation capacity, with only 23.6% attenuation and a first-floor response approximately 3.3 times greater than that of pile foundations. Although the structural safety requirements are satisfied, the vibration levels at upper floors may still exceed the human comfort limit of 75 dB, with the pile-founded building reaching 85.38 dB. These findings improve the understanding of vibration transmission mechanisms under symmetric disturbance conditions and provide a scientific basis for foundation selection and vibration mitigation in urban tunneling projects.

Tunnel engineering is frequently undertaken in complex geological environments, which present heightened risks during construction and operation, particularly in active fault zones. This necessitates the enhancement of fault resistance. This study investigates the combined application of Steel–polypropylene Fiber Concrete Linings and Combined Seismic Joints through numerical simulation using ABAQUS 2023 (Dassault Systèmes, France). The findings demonstrate that this combination significantly enhances the fault resistance of tunnel structures, exhibiting substantial synergistic effects. In comparison with the utilization of Steel–polypropylene Fiber Concrete Linings as a standalone measure, the maximum reductions in longitudinal tensile and compressive strain were found to be 40.1% and 46.7%, respectively. Furthermore, peak equivalent compressive and tensile plastic strains were reduced by 60.3% and 51.1%, and tensile and compressive damage by 4.9% and 17.3%. Further analysis reveals that the steel fiber aspect ratio and the content of both steel and polypropylene fibers have varying effects on suppressing different damage forms in tunnel linings. It is evident that an augmentation in the steel fiber aspect ratio most effectively suppresses plastic zone deformation, while an increase in polypropylene fiber content significantly reduces tensile strain and tensile damage. The optimal level of fault resistance performance is achieved when the steel fiber content is set at 1.90%, the aspect ratio is 60, and the polypropylene fiber content is 0.15%. Furthermore, the adjustment of the combined arrangement parameters enables tunnel structures to adapt more effectively to diverse operational conditions, thus providing flexible design solutions for practical engineering applications.

With the increasing complexity of engineering environments in tunnel construction, the vibrations generated by shield tunneling in hard rock strata pose significant challenges to the operation and maintenance of adjacent tunnels. This study investigates the vibration characteristics induced by shield tunneling and provides an in-depth analysis of the propagation behavior of these vibrations within tunnel segments and surrounding soil layers. Through a combination of theoretical derivations, on-site monitoring, and numerical simulations, the research examines the distribution of vibration energy and its attenuation patterns with increasing propagation distance. The findings reveal that vibration energy is primarily concentrated in the low-frequency range (3–4 Hz) and follows an exponential decay trend as distance increases. Furthermore, the vibration response of neighboring tunnels is heavily influenced by the construction vibration source, with rapid energy attenuation observed over short distances. Numerical simulations conducted using PFC3D6.0 (Particle Flow Code) software validate the theoretical model and emphasize the critical roles of soil-damping properties and tunnel segment material characteristics in vibration attenuation. This study offers a robust theoretical framework and valuable data to support the control of tunnel vibrations and the optimization of construction practices.

Optimizing the mesoscopic structure of concrete based on energy dissipation theory is an effective approach to enhancing its performance. However, related works are limited, and the mathematical relationship between the mesoscopic structure and the energy dissipation mechanism remains unclear. In this study, image processing technology and MATLAB were employed to quantitatively characterize the mesoscopic structure of concrete. A mesoscopic model of concrete was constructed using PFC2D to study the influence of mesoscopic parameters on energy dissipation, and a mathematical model of energy dissipation incorporating mesoscopic parameters was fitted using a deep neural network. In addition, the genetic algorithm with associated individuals (GA‐AIs) was applied to optimize the mesoscopic parameters. The main findings are as follows: (1) Based on the entropy‐containing random aggregate method, Fourier shape reconstruction analysis, and density‐damping random field method, the aggregate spatial arrangement, shape characteristics, and mortar matrix characteristic property were quantified separately. (2) Under uniaxial compression, the three types of mesoscopic parameters showed positive correlations to varying degrees with the energy dissipation capacity of concrete. By adjusting these parameters, the energy dissipation capacity can be effectively modulated. (3) The GA‐AIs efficiently optimized the mesoscopic parameters, enabling effective control of the energy dissipation capacity of concrete. Based on the optimization results under a specific working condition, the algorithm can infer mesoscopic parameter values to meet different performance requirements for this condition.

This study aims to evaluate the feasibility and effectiveness of a modified adaptive genetic algorithm (AGA) with Universal Distinct Element Code (UDEC) simulation in analyzing fracture surface feature points of an anticline rocky slope. Using coordinate data from 30 fracture surface feature points, the traditional GA and modified AGA methods were compared, with the mean value of the normalized Mahalanobis distance indicating the reliability of the results. The study found that the modified AGA approach with UDEC had a significantly smaller mean value of normalized Mahalanobis distance than the traditional GA approach, demonstrating its higher accuracy and reliability in analyzing the fracture surface feature points of the rocky slope. Additionally, the research found that the location of the fracture surface of the anticline rocky slope is closely related to the inhomogeneous bulk density caused by weathering. These findings contribute to sustainability efforts by improving our understanding of the behavior of rocky slopes, informing better land management and infrastructure planning, and reducing uncertainties in predicting the behavior of rocky slopes for more sustainable infrastructure development and land management practices.