Based on the radionuclide distributions in sedimentary coal-bearing strata, this study analyzed the microrelease mechanisms of radon in coal-bearing strata. It was found that the microrelease process includes three stages: emanation, migration, and exhalation. Based on this, an experimental apparatus was independently designed for monitoring radon during compression of coal/rock samples from coal-bearing strata, whose major components include an electrohydraulic servocontrolled rock mechanics testing system, an airtight container, coal/rock samples, radon output device, and a continuous emanometer. The developed apparatus was preliminarily utilized for uniaxial compression tests on mudstone samples taken from the #21105 coalface of the Fourth Coal Mine in Yili Coalfield, China. The test results show that before sample failure under the uniaxial compressive load (UCL), the radon concentration is negatively correlated with the applied UCL and the magnitude of imposed elastic deformation. Increasing the applied load shortens the period of stable deformation, gradually decreasing the porosity of the rock, and as a result of declining the concentration of radon emanation from the rock. Finally, suggestions for future research are proposed, including mathematical equations to express the correlations between different experimental parameters and fractal characteristics of radon release from porous media.

Lime, fly ash, and alkaline residue are used widely as effective binders to solidify/stabilize heavy metal-contaminated expansive soil. Carbonation, however, may influence the effectiveness of solidification/stabilization (S/S) by decomposing hydration products and decreasing pH, which would seriously damage the long-term durability of stabilized soils. This study focused on the variation of leaching characteristics of solidified/stabilized lead-contaminated expansive soils before and after accelerated carbonation under the leachant of pH 3 and 5 by the semidynamic leaching test. After semidynamic leaching, leaching indexes such as the effective diffusion coefficient ( D e ), leachability index ( Lx ), and slope ( r c ) were used to reveal the ion leaching mechanism. The results indicated that the amount of Pb 2+ and Ca 2+ leached out under different pH conditions increased after carbonation, which confirmed that carbonate on solidified/stabilized lead (Pb) had a negative impact. Additionally, the D e values of Pb 2+ and Ca 2+ varied in the range of 1.16 E  − 10 cm 2 /s to 1.71 E  − 07 cm 2 /s, which demonstrated that ion migration was low. The contaminated soil solidified by lime and AR could be used in “controlled utilization” as Lx was higher than 9, and the leaching process was controlled by a dissolution reaction according to the analysis of r c . Moreover, the strong acidic leachant (pH = 3) resulted in more ions leaching out and lower pH in leachate compared with a mildly acidic leachant. Finally, with literature and experimental results, we found that the main reason for the increase of lead ion filtration of the carbonation reduced the pH value of the matrix and made the hydration products denatured and decomposed.

Tower crane accidents frequently occur in the construction industry, often resulting in casualties. The utilization of tower cranes involves multiple phases including installation, usage, climbing, and dismantling. Moreover, the hazards associated with the use of tower cranes can change and be propagated during phase alternation. However, past studies have paid less attention to the differences and hazard propagations between phases. In this research, these hazards are investigated during different construction phases. The propagation of hazards between phases is analyzed to develop appropriate safety management protocols according to each specific phase. Finally, measures are suggested to avoid an adverse impact between the phases. A combined method is also proposed to identify hazard propagation, which serves as a reference and contributes to safety management and accident prevention during different tower crane phases in the construction process.