Abstract
Very few studies have focused on diatomaceous earth slopes along high-speed railways, and the special properties of diatomaceous earth under alternating dry and wet conditions are unknown. This paper studies diatomaceous earth in the Shengzhou area, through which the newly built Hangzhou–Taizhou high-speed railway passes, and the basic physical and hydraulic properties of diatomaceous earth are analyzed by indoor test methods. A convenient, efficient, and controllable high-speed railway slope artificial rainfall simulation system is designed, and in situ comprehensive monitoring and fissure observation are performed on site to analyze the changes in various diatomaceous soil slope parameters under rainfall infiltration, and to explore the cracking mechanisms of diatomaceous earth under alternating dry and wet conditions. The results indicate extremely poor hydrophysical properties of diatomaceous earth in the Shengzhou area; the disintegration resistance index values of natural diatomaceous earth samples subjected to dry and wet cycles are 1.8–5.6%, and the disintegration is strong. Comprehensive indoor tests and water content monitoring show that natural diatomaceous earth has no obvious influence when it contacts water, but it disintegrates and cracks under alternating dry and wet conditions. The horizontal displacement of both slope types mainly occurs within 0.75–2.75 m of the surface layer, indicating shallow surface sliding; after testing, natural slope crack widths of diatomaceous earth reach 10–25 mm, and their depths reach 40–60 cm. To guarantee safety during high-speed railway engineering construction, implementing proper protection for diatomaceous earth slopes is recommended.
Highlights
During on-site construction, diatomaceous earth slopes are exposed to the natural environment after excavation
Indoor tests on natural expansive soils were conducted in Nanning
The reason for the sudden change in the water content was that the original structure of the diatomaceous earth was destroyed by the borehole construction at the measurement point [38], and the backfill was not dense, resulting in rapid infiltration after the rainfall began; the water structure of the diatomaceous earth was destroyed by the borehole construction at the measurement point [38], and the backfill was not dense, resulting in rapid infiltration after the rainfall began; the water content increased abruptly; The diatomaceous earth slope was excavated during artificial rainfall simulation, and rainfall infiltration was assessed
Summary
As of the end of 2020, China’s operating railway mileage had reached 146,000 km, of which 37,900 km were high-speed railways. During on-site construction, diatomaceous earth slopes are exposed to the natural environment after excavation. Under the action of alternating wet and dry conditions, the destruction mechanism of diatomaceous earth and the dynamic evolution of diatomaceous earth slope parameters have become issues that urgently need to be studied. The existing literature contains very few studies on diatomaceous earth slopes, and the special properties of diatomaceous earth under the action of dry and wet cycles are not well understood. On loess and expansive soil slopes, a lot of work has been done by scholars in the past; there is deeper research on the special properties of loess and swelling soil under the action of alternating wet and dry conditions, and a lot of practice has been done in combination with actual slope engineering; the main research results are shown in
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