The strip filling method in underground reservoir needs high strength to achieve the requirements of water storage. In order to address the challenges associated with costly and weak filling materials, this study aimed to develop an economically efficient and high-strength gangue-based geopolymer backfill material (GBGBM). To achieve this, the Taguchi method was employed to design a series of 25 experiments, each consisting of four factors and five levels. This study focused on investigating the effects of different gangue gradation levels, sand ratios, water binder ratios (w/b), and aggregate binder ratios (a/b) on the working characteristics and unconfined compressive strength (UCS) of the GBGBM. The optimal combination of the GBGBM was determined by employing a signal-to-noise ratio (S/N)-based extreme difference and variance analysis. The results revealed that the w/b ratio exerted the most substantial influence on both the slump and UCS. Specifically, when employing a gradation of 50%, a sand ratio of 55%, an a/b ratio of 2.5, and a w/b ratio of 0.64, the slump measured 251.2 mm, the UCS at 3d reached 5.27 MPa, and the UCS at 28d amounted to 17.65 MPa. These findings indicated a remarkable improvement in early UCS by 131.14% and the late UCS by 49.45% compared to gangue-based cement backfill material (GBCBM). Additionally, this study examined the hydration products and microstructures of both GBGBM and GBCBM using X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) analyses. Significantly, the GBGBM exhibited notable advantages over the GBCBM, including a 78.16% reduction in CO₂ emissions, a 73.45% decrease in energy consumption, and a 24.82% reduction in cost. These findings underscore the potential of GBGBM as a sustainable and cost-effective alternative to GBCBM.

The load capacity of reinforced concrete structure will decrease by chloride ingress in coastal region. In this paper, the corrosion probability and flexural strength of a typical reinforced concrete beam design under the influence of temperature and humidity was obtained by the Monte Carlo method. The relationship between flexural strength, temperature, relative humidity, and geometric parameters was established. The annual average temperature and relative humidity were treated as random variables together with the geometric size and concrete compressive strength. The corrosion probability and flexural strength in a wave splashing zone, coastal atmospheric zone, and offshore atmospheric zone were calculated. The results show that the corrosion probabilities of the three regions are obviously different. When the standard deviation of temperature is less than 1.5 °C, the temperature can be treated as a constant in the calculation of the concrete cracking probability in the wave splashing zone. A binary logistic regression formula was given to predict whether the randomness of temperature and humidity should be considered in the offshore atmospheric zone. When the standard deviation of the temperature is less than 1 °C, the temperature randomness has no significant effect on the flexural strength of beams in the wave splashing zone. The flexural strength distribution conforms to the normal distribution in the early stage of service and the Weibull distribution after concrete cracking.

In order to mitigate the vibration caused by fluid–structure interaction in water-conveying pipelines, a semi-active control method based on a magnetorheological (MR) damper is proposed. First, the partial differential equation governing the pipeline micro-element, which is simply supported at both ends, is formulated. This equation is then transformed into state-space expressions through non-dimensionalization and the Galerkin method. Based on passive dissipative control theory, a semi-active control law ensuring Lyapunov global asymptotic stability is derived based on the relative motion between the dynamic vibration-absorbing mass and the pipeline. Next, an on–off control algorithm is designed for the MR damper. The results of simulation and hardware-in-loop experiments demonstrate that the semi-active control law can significantly reduce the vibration of the pipeline system. The contribution of this research is to propose a new MR tuned mass damper (MR-TMD) to suppress vibration in water-conveying pipelines. The proposed MR-TMD scheme and its control method provide a theoretical basis and practical reference for the engineering application of semi-active vibration control in water-conveying pipelines.

This study examined the depth–width correlation of actual shrinkage-induced cracks and its influence on the diffusion properties of concrete. An experimental setup of restrained slabs was utilized to induce the shrinkage cracks, and the geometry characteristics were quantified with image analysis technology. The results indicated the depth–width scaling $\lambda$ of shrinkage cracks increases with crack width and was almost constant when the crack width was approximately 0.3 mm or more, and the tip angle of shrinkage cracks is about 1–2 degrees. The diffusion coefficients of concretes were measured by a conductivity test method. A series-parallel composite model with $\lambda$ was devised to evaluate the diffusivity of shrinking cracked concrete. It was shown that the equivalent diffusion coefficient depended greatly on the crack depth instead of the crack width, and it was found to be a nonlinear relationship versus the width combining with $\lambda$ . The diffusion coefficient of the crack D_cr was correlated to both crack width and $\lambda$ , and increased with crack width. When the crack width is higher than 0.2 mm D_cr becomes constant, where the value obtained was 87% of the diffusion coefficient in free solution.

The existing bearing capacity model for grouting sleeves is synthesized in this study. Utilizing the principles of thick-walled cylinders in elastic mechanics, a comprehensive ultimate bearing capacity model for grouting sleeves is developed using conventional material parameters. To validate the efficacy of the model, 18 steel bar grouting sleeves of varying anchor lengths, steel bar diameters, and designs were tested. The outcomes indicate minimal errors in the computational results and demonstrate superior applicability when juxtaposed with established grouting sleeve bearing capacity formulas.