With the rapid development of rail transit in China, the number and scale of underground engineering construction have increased significantly, and a large amount of shield muck has been generated, which has brought great challenges to the urban environment. The reuse of shield muck has become an important research direction in underground engineering construction. In this paper, a nonsintered brick is prepared with shield muck soil as the matrix. The influence of different doping amounts of lime, fly ash, cement, and polyvinyl alcohol on porosity, density, water absorption, saturation coefficient, compressive strength, and other properties was explored to realize the resource utilization of shield dregs and at the same time obtain excellent performance nonsintered bricks. Through research, it is found that when the lime doping amount is 10% and the cement doping amount is 5%, with the increase of the fly ash doping amount, the overall compressive strength increases significantly, and the maximum compressive strength can reach 13.69 MPa. Although the doping of trace amounts of polyvinyl alcohol reduces the compressive strength, it can significantly reduce the compressive strength and mass loss rate after 15 freeze‐thaw cycles.

Hydrological tracer testing is an effective way to determine the law of recharge and the transport of groundwater. In karst collapse mine water treatment, the hydrological tracing test can determine information such as the runoff velocity and the pattern of underground runoff, so that targeted grouting becomes possible. In this paper, NaCl was used as a tracer, and the content of the tracer was determined by the chloride ion selective electrode method. The NaCl concentration–time curve was plotted, and we obtained a tracer test method that can determine the runoff of the karst quantificationally. The method can quantificationally obtain the groundwater transport velocity, runoff pattern, and connectivity. This combination of grouting rate, grouting pressure, and setting time realized the localized targeted grouting and achieved a significant water damage control effect.

To address the problems of complex influencing factors of chamber pressure and delayed response in manual regulation during shield construction, this study proposes a chamber pressure prediction and parameter-optimization method integrating SSA-RF and PSO based on field tunneling data from 1082 rings. First, on the basis of conventional tunneling parameters, muck improvement parameters, including the cumulative amount of foam mixture in the current ring, the cumulative amount of cutterhead water spray in the current ring, and the cumulative amount of bentonite in the current ring, are introduced. Nine key input variables are then screened by combining Pearson correlation coefficient analysis and distance correlation coefficient analysis. Subsequently, an SSA-RF chamber pressure prediction model is established. The results show that the model achieves an R² of 0.9968 and a MAPE of only 0.34% on the test set, outperforming the other models. Furthermore, with the objective of minimizing the deviation between the predicted chamber pressure and the target value, the PSO algorithm is used to optimize the propulsion speed and the rotation speed of the screw conveyor. The results indicate that, based on the predicted chamber pressure values, the PSO algorithm can output optimized adjustment suggestions for propulsion speed and screw conveyor rotation speed, thus realizing model-assisted regulation of chamber pressure. This study can provide a reference for chamber pressure prediction and auxiliary regulation of tunneling parameters during earth pressure balance shield tunneling.

The shield tunneling method is widely used for underground space development in the world, where vibratory screening is a critical pretreatment stage for resource utilization of shield muck. However, existing parameters for vibrating screens are mainly based on soft soil and sandy cobblestone strata. Research regarding shield muck from moderately weathered strata remains scarce, leading to poor equipment adaptability and low efficiency. This study focuses on a dry granular system of typical shield muck from moderately weathered strata after washing, drying, and homogenization. By combining laboratory standard sieve tests with EDEM discrete element simulations, a DEM numerical model of double-deck vibratory screening was established. Using single-factor controlled variables and orthogonal experimental designs, the comprehensive influences of vibration frequency, amplitude, and screen inclination angle on a double-deck screen were systematically investigated. Within the investigated parameter ranges, the screen inclination angle produced a relatively large variation in screening efficiency. Based on the preliminary evaluation using the numerical model developed in this study, a vibration frequency of 15 Hz, an amplitude of 2.0 mm, and a screen inclination angle of 12° exhibited favorable overall screening performance among the investigated parameter combinations, yielding upper- and lower-deck screening efficiencies of 95.16% and 82.96%, respectively. The results indicate that changes in the feed state of the lower deck induced by upper-deck pre-classification may be associated with the differentiated responses of the two screen decks to operating parameters, providing a reference for multi-stage screening analysis and parameter selection for shield muck from moderately weathered strata.