Guangxi Transportation Research Institute

In underground structural systems, mid-partition walls exhibit significant seismic vulnerability in large-span prefabricated underground structures due to their relatively slender cross-sections and lower overall stiffness than primary structures. Leveraging the superior mechanical properties of Ultra-High Performance Concrete (UHPC), this study designed prefabricated underground mid-partition walls incorporating two connection types: UHPC grouted sleeve joints (Specimen A) and hybrid UHPC grouted sleeve-prestressed anchor joints (Specimen B). Large-scale quasi-static tests were conducted to evaluate the seismic performance of both configurations. The experimental results demonstrated that both joint configurations provided sufficient connection strength and enhanced the plastic deformation capacity of the mid-partition walls. All specimens exhibited biaxial compression-bending failure characteristics, with extensive concrete spalling at the base of the wall and yielding reinforcement deformation, ultimately forming plastic hinges in the localized area at the wall base. Compared with Specimen A, Specimen B exhibited a 19.3% increase in peak load, and a 24.8% increase in cumulative hysteretic energy dissipation. The reinforcement strain at the wall base was significantly higher than other areas, indicating that this region experienced the maximum bending moment and is a critical weak link in the seismic design of mid-partition walls. This research elucidates the enhancement mechanism of prestressed reinforcement for UHPC grouted sleeve connections. It quantifies seismic performance improvements, providing a robust foundation for implementing UHPC grouted sleeve technology in prefabricated underground structures.

This study systematically analyzed the influence mechanism of the ratio of organic fertilizer (OF), slow-release fertilizer (SRF), and rice straw (RS) on the crack ratio and root content of expansive soil through Box-Behnken experimental design (BBD) and quadratic polynomial regression model. The results show that RS has the greatest contribution to fissure suppression. For every 0.1% increase in its content, the crack ratio decreases by 0.204% ( p < 0.001). However, excessive OF (>10%) significantly increases the crack ratio by exacerbating the non-uniformity of drying shrinkage ( β = 0.132, p < 0.001). Root content is mainly positively driven by RS ( β = 0.126, p < 0.001), but RSF inhibits root growth through salt cementation ( β = −0.042, p = 0.003). In terms of interaction, OF and RS synergistically increase root content ( β = 0.104, p = 0.002), but OF and SRF antagonistically increase fissure risk ( β = 0.042, p = 0.082). Multi-objective optimization yields three typical ratios: fissure priority scheme (RS = 0.70%, SRF = 0.83 kg/m 3 , OF = 8.2%, crack ratio 1.5%), balanced scheme (RS = 0.65%, SRF = 0.75 kg/m 3 , OF = 9.0%, root content 1.02 mg/cm 3 ), and ecological priority scheme (RS = 0.55%, SRF = 0.60 kg/m 3 , OF = 11.5%, root content 1.25 mg/cm 3 ). Model verification shows high prediction accuracy (crack ratio R 2 = 0.91, RMSE = 0.12%; root content R 2 = 0.93, RMSE = 0.11 mg/cm 3 ), but in areas with high OF (>12%), drainage measures need to be combined to control the risk of salinization. This study provides a quantitative ratio design and risk control basis for the improvement of expansive soil with agricultural waste.

Wet–dry cycles are a key factor aggravating the durability degradation of foam concrete. To address this issue, this study prepared bentonite slurry–steel slag foam concrete (with steel slag and cement as main raw materials, and bentonite slurry as admixture) using the physical foaming method. Based on 7-day unconfined compressive strength tests with different mix proportions, the optimal mix proportion was determined as follows: mass ratio of bentonite to water 1:15, steel slag content 10%, and mass fraction of bentonite slurry 5%. Based on this optimal mix proportion, dry–wet cycle tests were carried out in both water and salt solution environments to systematically analyze the improvement effect of steel slag and bentonite slurry on the durability of foam concrete. The results show the following: steel slag can act as fine aggregate to play a skeleton role; after fully mixing with cement paste, it wraps the outer wall of foam, which not only reduces foam breakage but also inhibits the formation of large pores inside the specimen; bentonite slurry can densify the interface transition zone, improve the toughness of foam concrete, and inhibit the initiation and propagation of matrix cracks during the dry–wet cycle process; the composite addition of the two can significantly enhance the water erosion resistance and salt solution erosion resistance of foam concrete. The dry–wet cycle in the salt solution environment causes more severe erosion damage to foam concrete. The main reason is that, after chloride ions invade the cement matrix, they erode hydration products and generate expansive substances, thereby aggravating the matrix damage. Scanning Electron Microscopy (SEM) analysis shows that, whether in water environment or salt solution environment, the fractal dimension of foam concrete decreased slightly with an increasing number of wet–dry cycle times. Based on fractal theory, this study established a compressive strength–porosity prediction model and a dense concrete compressive strength–dry–wet cycle times prediction model, and both models were validated against experimental data from other researchers. The research results can provide technical support for the development of durable foam concrete in harsh environments and the high-value utilization of steel slag solid waste, and are applicable to civil engineering lightweight porous material application scenarios requiring resistance to dry–wet cycle erosion, such as wall bodies and subgrade filling.

With the gradual adoption of smart hardware such as the Internet of Things (IoT) in warehousing and logistics, the efficiency bottlenecks and resource wastage inherent in traditional storage management models are now poised for breakthrough through digital and intelligent transformation. This study focuses on the cross-border cold chain storage scenario for Malaysia’s Musang King durians. Influenced by the fruit’s extremely short 3–5-day shelf life and the concentrated harvesting period in primary production areas, the issue of delayed dynamic demand response is particularly acute. Utilizing actual sales order data for Mao Shan Wang durians from Beigang Logistics in Guangxi, this study constructs a demand forecasting model integrating Bayesian optimization with bidirectional long short-term memory networks (BO-BiLSTM). This aims to achieve precise forecasting and optimization of cold chain storage inventory. Experimental results demonstrate that the BO-BiLSTM model achieved an R2 of 0.6937 on the test set, with the RMSE reduced to 19.1841. This represents significant improvement over the baseline LSTM model (R2 = 0.5630, RMSE = 22.9127). The bidirectional Bayesian optimization mechanism effectively enhances model stability. This study provides a solution for forecasting inventory demand of fresh durians in cold chain storage, offering technical support for optimizing the operation of backbone hub cold storage facilities along the New Western Land–Sea Trade Corridor.

In offshore construction, long-large marine construction square barges play a crucial role in lifting and sinking operations. These projects inevitably encounter complex and unstable ocean wave and current environments, where excessive hull movement can compromise both the accuracy and safety of construction activities. This study proposes a novel floating wave–current attenuation device to protect square barges. The hydrodynamic behavior of this innovative method is experimentally investigated and compared with that of different forms of protection in a large wave–current flume. Additionally, a sensitivity analysis for key parameters of the square barge and an optimization of the floating protection device are conducted in detail. The results show that the use of the floating protection device significantly reduces the dynamic response of the square barge. Specifically, there are reductions in sway, heave, roll, and relative cable force by nearly 10 times, 8 times, 12 times, and 5 times, respectively. Furthermore, during actual construction operations involving square barges, optimal protection methods and economic benefits can be attained by reducing the freeboard value, establishing appropriate protection spacing, and adjusting the tension of the mooring system. This study provides valuable insights into the protection of large marine construction square barges.

Green and low-carbon development has emerged as a pivotal direction in the global development agenda. In alignment with this trend, China has established a significant roadmap with its “3060” carbon peak and carbon neutrality goals. Under this strategic framework, various industries in China have initiated comprehensive carbon emission reduction efforts. Notably, the wastewater treatment sector has been a focal point, as China has consistently prioritized significant investments in this are a. While the country boasts a vast network of sewage systems, including extensive sewage discharge volumes, an extensive pipeline network, and a large number of wastewater treatment plants, these achievements come with substantial carbon emissions. This is primarily due to both the indirect carbon emissions resulting from energy consumption in the wastewater treatment process and the direct generation of greenhouse gases during treatment operations. To address these challenges and advance carbon emission reduction in the wastewater treatment industry, this study provides a comprehensive analysis of the current state of China’s wastewater treatment sector. By examining multiple pathways for carbon emission reduction in Chinese wastewater treatment plants—such as the utilization of sewage heat energy, innovative wastewater treatment processes, smart water applications, photovoltaic technology integration, and sludge resource recovery —this paper identifies actionable strategies for achieving low-carbon operation.