Jiao-Long Zhang

Prefabrication introduces non-monolithic joints into buried multi-cell box structures, but it remains unclear how the stiffness of internal partition-wall connections propagates through the structural frame to modify soil–structure interaction and dynamic earth pressure. This study isolates this mechanism through shaking table tests on two fully buried prefabricated double-cell models derived from an underground wastewater tank. Both models were tested under empty conditions to exclude hydrodynamic effects. Set-E employed epoxy-resin connections to represent rigid joints at the partition-wall–slab interfaces, whereas Set-S used lower-stiffness silicone connections to represent flexible joints at the same interfaces. White-noise excitation and sinusoidal excitations ranging from 2 to 14 Hz, with nominal base PGAs of 0.06, 0.13, and 0.18 g, were applied. The fundamental site-dominated frequency remained at approximately 6.04 Hz for both configurations, indicating that the low-frequency response was governed primarily by the soil. The influence of joint flexibility became more pronounced at higher frequencies: the near-field transfer-function peak at 20–21 Hz was approximately 29% lower in Set-S than in Set-E. Set-E exhibited greater structural acceleration amplification and more localized concentrations of dynamic earth pressure and strain. In contrast, Set-S reduced structural acceleration while redistributing earth pressure and deformation over a broader wall region. A frame-coupled dynamic earth pressure model was developed by extending the Brandenberg formulation to incorporate the double-cell configuration, joint rotational stiffness, depth-dependent soil motion, and coupled structural and foundation effects. The model captured the localized pressure concentration in Set-E and the upward pressure redistribution in Set-S more effectively than conventional isolated-wall formulations. These results demonstrate that partition-wall connection stiffness regulates the seismic load-transfer path and the spatial distribution of structural demand rather than uniformly reducing the seismic response.

The interfacial adhesion between fresh concrete and a substrate is crucial for printcrete linings in mountain tunnels. The interfacial adhesion is time‐dependent and can evolve quickly when the concrete is in a fresh state. This study examines the impact of adding calcium sulfoaluminate (CSA) cement on the time‐dependent interfacial adhesion. The dosages of CSA cement include 0%, 2%, 4%, and 6% by mass of binder. After various periods of rest, the interfacial adhesion is quantified by applying tensile or shear stresses to the interface until debonding occurs. The resting times range from 1 to 32 min after the formation of the interface. Fast tack tests (FTTs) and fast shear tests (FSTs) were conducted to quantify the time‐dependent interfacial adhesion subjected to tensile stress and shear stress, respectively. The results showed that the increase in resting time and the addition of CSA cement can significantly enhance interfacial adhesion. A time‐dependent interfacial maximum tensile stress model and a time‐dependent interfacial maximum shear stress model were established. The models quantify the effect of the hydration degree of the cementitious materials and the replacement ratio of CSA cement on the interfacial adhesion. The models were validated by comparing the calculated results with the test results.

High‐geothermal environments present significant challenges for tunnel construction and operation while simultaneously offering promising opportunities for renewable energy utilization. In response, this study proposes a novel high‐geothermal tunnel thermoelectric generator (HGT‐TEG) system, designed to convert geothermal heat into electrical energy. A numerical model was developed to investigate the heat‐transfer characteristics and power generation performance of the system. The model was validated through comparison with both on‐site measurements and laboratory experiments. A parametric analysis revealed that the thickness of the thermal insulation layer and the spacing of thermoelectric modules (TEMs) are key factors, affecting the power output. Furthermore, the integration of thermal conductive layers significantly enhanced the effective temperature gradients across TEMs, thereby improving the overall system performance. Under geothermal conditions with a surrounding rock temperature around 92°C, an HGT‐TEG system, featuring 30 cm spacing between TEMs in a 1 km tunnel segment (8 m wide, 10 m high), generated an estimated 4867 kWh of electricity, annually. The proposed HGT‐TEG system represents a viable and sustainable solution for geothermal energy harvesting, contributing to the resilience and sustainability of tunnel infrastructure in geothermally active regions

3D-printed mortar (3DPM) is associated with significant cement consumption, which raises substantial environmental concerns. This study investigates the reuse of sugarcane bagasse ash (SBA), which has a high SiO ₂ content, in 3DPM to reduce carbon emissions and to promote sustainable development. The raw SBA was first dried and then ground. Then, five mixtures with varying SBA dosages, ranging from 0 to 20% cement replacement, were developed and tested. This study examines the effects of SBA on key properties of 3DPM, such as flowability, hydration kinetics, setting time, and compressive strength. The results indicate that increasing SBA content reduces the flowability of the mixtures. It significantly reduces the setting time from 207.5 min of the control mix to 49.5 min as the replacement ratio is 20% due to finer particles. The isothermal calorimeter test results indicate that SBA accelerates the cement hydration process, potentially reducing the usage of an accelerator in 3DPM. Including SBA in the mortar mix significantly increased compressive strength within the first 24 h and also up to 28 days. This accelerated reaction boosts the early-age strength development of the concrete mixture, making it especially suitable for applications that demand rapid strength gain.

Energy storage is a critical component of the modern electrical system, alongside power plants, grids, and users. Many methods of storing electrical power have made significant progress. This paper presents a perspective on storing electrical energy in cities in the form of liquid nitrogen and its associated thermal energy byproducts. Statistics on city electrical consumption indicate that commercial services account for more than 50% of total usage, with Heating Ventilation Air Conditioning comprising 50% of this power consumption, both on a daily and seasonal basis. This highlights the potential for electrical consumption to manifest as cold energy in summer and thermal energy in winter. To address this, a liquid nitrogen energy storage and release (LN-ESR) system is proposed, capable of storing large quantities of both cold and thermal energy. The stored cold energy can be released during summer to regulate building air temperature, while the resulting expanded gas could drive a gas turbine to generate electricity. In winter, the thermal energy can be used to heat buildings. A preliminary techno-economic analysis is presented, comparing the LN-ESR system with conventional compressed air energy storage (CAES) and evaluating its feasibility for underground storage applications.

Energy storage is a critical component of the modern electrical system, alongside power plants, grids, and users. Many methods of storing electrical power have made significant progress. This paper presents a perspective on storing electrical energy in cities in the form of liquid nitrogen and its associated thermal energy byproducts. Statistics on city electrical consumption indicate that commercial services account for more than 50% of total usage, with Heating Ventilation Air Conditioning comprising 50% of this power consumption, both on a daily and seasonal basis. This highlights the potential for electrical consumption to manifest as cold energy in summer and thermal energy in winter. To address this, a liquid nitrogen energy storage and release (LN-ESR) system is proposed, capable of storing large quantities of both cold and thermal energy. The stored cold energy can be released during summer to regulate building air temperature, while the resulting expanded gas could drive a gas turbine to generate electricity. In winter, the thermal energy can be used to heat buildings. A preliminary techno-economic analysis is presented, comparing the LN-ESR system with conventional compressed air energy storage (CAES) and evaluating its feasibility for underground storage applications.

The mixing quality of 3D printable concrete, hereafter referred to as printcrete, is governed by the concurrent attainment of spatial homogeneity and rheological build-up. However, existing monitoring protocols suffer from a fundamental sensing disconnect. Visual inspection is inherently insensitive to bulk stiffening, whereas torque monitoring reflects only volume-averaged resistance and often overlooks localized compositional heterogeneities. To bridge this gap, this study develops an interpretable multimodal monitoring framework specifically designed for the automated mixing of printcrete by integrating computer vision, dynamic torque sensing, and thermal profiling. The proposed system establishes a physics-informed decision logic where the visual texture index serves as a high-sensitivity constraint for particle dispersion entropy, and dynamic torque characterizes the evolution of bulk yield stress. Crucially, thermal profiling acts as a definitive chemical arbiter, utilizing the order-of-magnitude difference in thermal derivatives to autonomously differentiate the distinct thermodynamic signatures across dry-mixing, lubricated liquid dispersion, and accelerator-induced rapid hydration. Experimental validation confirms that this cross-modal fusion effectively resolves the blind spots inherent to single-modal method, identifying the optimal timings for water dosing, admixture injection, and material discharge. By transitioning from static recipe adherence to dynamic performance control, the system ensures the precise rheological consistency required for defect-free extrusion, establishing a foundational architecture for closed-loop, unmanned, high-quality production of printcrete.