Rapid and accurate assessment of blast loads in complex urban blocks is critical for efficient blast-resistant structural design and post-disaster damage evaluation. However, traditional methods, including empirical formulas, physical models, and numerical simulations, struggle to simultaneously achieve high computational efficiency and prediction accuracy. Furthermore, existing deep learning-based blast load prediction models are hard to be applied in complex urban block scenarios. To achieve rapid and accurate assessment of blast loads in complex urban street blocks, a physics-information and data fusion-driven method is proposed. The core idea of the method is a “spatial partitioning and progressive inference” strategy, which involves constructing distinct rapid prediction models for “the detonation street” and “non-detonation streets”. These models then collaborate synergistically via their shared boundary pressures to predict the spatiotemporal evolution of the pressure field across the entire urban block. The two network models incorporate the results from method of images, signed distance fields, and energy density factors to integrate key physical features of the flow field. For the architectures, the two models adopt a 3D-UNet and a cascaded network composed of a 2D-UNet and a 3D-UNet, respectively. The target outputs for both networks were generated using a validated numerical simulation method, which were then used to train the models. Evaluation of the model’s predictive performance demonstrates that the proposed method accurately predicts the spatiotemporal evolution of the pressure field. The relative error between the predicted flow field and numerical simulation results is within 20% in both detonation and non-detonation streets. Moreover, the method effectively captures the pressure-time histories at specified locations. The inference time of the proposed dual-network collaborative method is approximately 2% of the computation time of the corresponding numerical simulation, and the flow field storage cost for a single time step is less than 0.2% of a D3PLOT file, thereby significantly reducing computational and storage costs. The research provides a novel method for the rapid assessment of blast loads in large-scale, complex urban blocks, offering efficient decision-making support for the blast-resistant design and evaluation of urban buildings.

The quasi-static pressure thermodynamic model for confined explosions provides an effective characterization of pressure evolution with mass-to-volume ratio m/V, and derivation of physical quantities such as gas adiabatic index from products and temperature. However, the thermodynamic model based on detonation and combustion equations that neglects reaction equilibrium demonstrates growing deviations from the quasi-static pressure curve in UFC 3-340-02 blast-resistant design standard after carbon precipitates in detonation products, and existing research inadequately addresses the necessity of incorporating reaction equilibrium for various physical quantities in TNT confined explosion thermodynamic models. In order to investigate the influence of reaction equilibrium on thermodynamic calculation results, the model neglecting reaction equilibrium was modified based on the energy conservation equation of isochoric processes and the solid carbon precipitation phenomenon. The modified model has a consistency with the UFC curve for m/V≥0.371 kg/m³. Then, a comparative analysis was conducted on the results of thermodynamic models considering and not considering the reaction equilibrium based on the unified solution framework. The results indicate that incorporating chemical equilibrium into quasi-static pressure calculation introduces a maximum relative deviation below 20%, and critical thresholds alters, i.e., the m/V for carbon precipitation shifts from 0.371 to 3.850 kg/m³, and peak temperature transitions from 0.371 to 0.680 kg/m³. Significant divergence in mole numbers of product composition emerges progressively when m/V exceeds 0.1 kg/m³. Therefore, the reaction equilibrium-based thermodynamic model is a more rational choice for calculating quantities related to components and temperature in TNT confined explosions with m/V>0.1 kg/m³. Finally, a simplified calculation method for products, temperature, and pressure during the quasi-static phase of TNT confined explosions considering reaction equilibrium is proposed based on symbolic regression algorithm. The research contributes to a theoretical understanding of equilibrium effects on thermodynamic model results and the practical implementation of rapid parameter estimation in TNT confined explosion scenarios.