Blasting profile evaluation of sand-mud interbedded surrounding rock during the large-span tunnel construction.

The sand-mud interbedded surrounding rock contains discontinuities, such as horizontal bedding, joints, weak planes and weak interlayers. Drilling and blasting construction in this kind of surrounding rock is very likely to cause very serious over-/under-excavation phenomenon and excessive damage to surrounding rock, and the contour flatness after smooth blasting of the tunnel is also difficult to be guaranteed, which increases subsequent construction procedures and reduces production efficiency. In order to effectively evaluate the smooth blasting effect of the sand-mud interbedded surrounding rock tunnel, taking a tunnel project in southwest China as the research background, the blasting numerical simulation of the sand-mud interbedded surrounding rock tunnel was carried out using the dynamic analysis program, and the corresponding blasting optimization scheme was obtained. Subsequently, based on fuzzy mathematical theory, the evaluation system of blasting effect of sand-mud interbedded tunnel was established by combining the evaluation criteria of tunnel smooth blasting quality. Immediately afterwards, the weights of each influencing factor index were determined, and the blasting shaping effect of the original blasting scheme and the optimized blasting scheme was evaluated. Finally, the results have shown that the optimized tunnel blasting profile effect was better than the original blasting scheme. The corresponding research results have certain guiding significance for similar tunnel blasting effect evaluation and blasting parameter design.

QALY-type preference and willingness-to-pay among end-of-life patients with cancer treatments: a pilot study using discrete choice experiment.

PURPOSE: Quality-adjusted life-year (QALY) is a dominant measurement of health gain in economic evaluations for pricing drugs. However, end-of-life (EoL) patients' preference for QALY gains in life expectancy (LE) and quality of life (QoL) during different disease stages remains unknown and is seldom involved in decision-making. This study aims to measure preferences and willingness-to-pay (WTP) towards different types of QALY gain among EoL cancer patients. METHODS: We attributed QALY gain to four types, gain in LE and QoL, respectively, and during both progression-free survival (PFS) and post-progression survival (PPS). A discrete choice experiment including five attributes (the four QALY attributes and one cost attribute) with three levels each was developed and conducted with 85 Chinese advanced non-small cell lung cancer patients in 2022. All levels were set with QALY gain/cost synthesised from research on anti-lung cancer drugs recently listed by Chinese National Healthcare Security Administration. Each respondent answered six choice tasks in a face-to-face interview. The data were analysed using mixed logit models. RESULTS: Patients valued LE-related QALY gain in PFS most, with a relative importance of 81.8% and a WTP of $43,160 [95% CI 26,751 ~ 59,569] per QALY gain. Respondents consistently preferred LE-related to QoL-related QALY gain regardless of disease stage. Patients with higher income or lower education levels tended to pay more for QoL-related QALY gain. CONCLUSION: Our findings suggest a prioritised resource allocation to EoL-prolonging health technologies. Given the small sample size and large individual heterogeneity, a full-scale study is needed to provide more robust results.

Effects of high temperature and acidic solutions on the pore characteristics and mechanical properties of sandstone.

Sandstone is a common construction material widely distributed in mountain tunnels. Its stability determines the safety and service life of tunnel projects. The surrounding rock of the tunnel is subject to frequent fire incidents and long-term erosion by acidic groundwater throughout its entire life cycle. This study investigated the pore characteristics and mechanical properties of sandstone under different high temperatures and acidic solutions. The T2 spectrum distribution, pore size distribution, porosity, compressive strength, and elastic modulus of sandstone were observed through uniaxial compression tests and nuclear magnetic resonance (NMR) tests. The results showed that high temperature and acidic solutions significantly affected the T2 spectrum distribution, pore size distribution, porosity, compressive strength, and elastic modulus of sandstones, and their effects on the pore structure and mechanical properties of sandstone differed in each stage. The effect of high temperature on the pore structure and mechanical properties of sandstone was stronger than that of the acidic solutions. In addition, the mechanism of damage formation is characterized by the porosity variation of sandstone. The pore structure of sandstone showed a close linear relationship with mechanical properties, indicating that changes in microstructure inevitably affected the macroscopic mechanical properties of sandstone. These findings can guide the construction and repair of rock failure induced by fire and acidic groundwater, providing a reference for associated tunnel projects.