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In this paper, a resilience assessment framework for microencapsulated self-healing cementitious composites is proposed based on a micromechanical damage-healing model. A 3D micromechanical analytical model is constructed to analyze the performance evolution during the damage-healing process of self-healing concrete. The resilience assessment of microencapsulated self-healing concrete is defined by virtue of the residual stiffness, self-healing effect on stiffness and damage cumulative on stiffness, which corresponds to three main features of resilience; namely, the robustness, recoverability and adaptability. The assessment results indicate that the release of healing agents within microcapsules and healing process of extended microcracks allows the microencapsulated self-healing concrete to have higher resilience than conventional concrete. Moreover, a parameter sensitivity analysis is conducted to investigate the influence of the healing efficiency, the applied initial damage and the fracture toughness of the repaired microcrack on resilience of microencapsulated self-healing concrete. The results indicate that higher healing efficiency and applied initial damage leads to high resilience, and fracture toughness of the repaired microcrack makes less difference to the results. The findings of this paper lay a theoretical foundation for the resilience design of self-healing material layer of underground structures. [ABSTRACT FROM AUTHOR]

The high-energy-level dynamic compaction method is widely used in various foundation treatment projects, but its reinforcement mechanism still lags behind the practice. In view of this, a three-dimensional fluid–solid coupling dynamic analysis model was established on the basis of the FDM–DEM coupling method. The variation trends of crater depth, soil void ratio, vertical additional dynamic stress, and pore water pressure during the process of dynamic compaction were analyzed. The results indicate that the curvature of the crater depth fitting curve gradually decreases with the increase in strike times, tending to a stable value. The initial particle structure is altered by the huge dynamic stress induced by dynamic compaction. As strike times increase, the soil void ratio decreases gradually. The vertical additional dynamic stress is the fundamental reason resulting in foundation compaction. Precipitation preloading before dynamic compaction can improve the reinforcement effect of dynamic compaction, making up for the deficiency that the vertical additional dynamic stress attenuates rapidly along the depth direction. The simulated CPT results illustrate that the modulus of foundation soil can be increased by 3–5 times after dynamic compaction. The research results can provide important reference for similar projects. [ABSTRACT FROM AUTHOR]

Indoor HCHO elimination is of great significance for breathing safety. Herein, we report CeO2 nanorods decorated by Pt nanoparticles for HCHO oxidative elimination. The resultant Pt/CeO2 catalysts show a close relationship between oxidation performance and ceria nanorod crystallite sizes. In comparison to 0.2Pt/CeO2-B and 0.2Pt/CeO2-C catalysts that have ceria crystallite sizes of 11 and 18 nm, respectively, the 0.2Pt/CeO2-A catalyst that has a ceria crystallite size of 8 nm exhibits the highest oxidation performance. From the results of Raman, O2-TPD, and H2-TPR analyses, the size–performance relationship is suggested to be contributed from the highest oxygen vacancy, the highest oxygen mobility, and the strongest redox in the 0.2Pt/CeO2-A catalyst because of the smallest ceria size. In situ DRIFTS verifies that mobile oxygen from the ceria surface lattice oxygen activated the oxygen molecules at the oxygen vacancy and the hydroxyl group transformed the intermediates of dioxymethylene and formate species. [ABSTRACT FROM AUTHOR]

Parameters as well as their corresponding reference values, adopted to control the compaction quality during the construction of High-speed Rail(HSR) embankments in different countries are summarised in this paper. Different measurement methods for the degree of compaction are analysed with the comparison of the features of various plate loading tests. To investigate the relationships between different compaction control parameters, we conducted in-situ compaction tests on three particular subdivisional railway earthworks at Zhangjiakou-Datong HSR and Inner Mongolia-Jiangxi Railway: a bridge foundation pit below the embankment-bridge transition section, a geogrid-reinforced cushion above embankment foundation, and an excavated channel for drainage ditch. We investigate the relations of the Dynamic Deformation Modulus (Evd) versus the Reaction Modulus (K30), Evd versus the compaction coefficient (K) by analysing the measured data. The analysis result shows good linear correlations between Evd and K30, as well as Evd and K. Based on the analysis performed in this paper combined with our engineering practices, recommended reference values of the compaction control indicators for bridge foundation pit below a transition section and the bottoms of drainage ditches are also proposed in this paper. [ABSTRACT FROM AUTHOR]