Construction method of expressway insulating regulation subgrade in permafrost areas

Abstract

The invention relates to a construction method of an expressway insulating regulation subgrade in permafrost areas. The method comprises: impacting and rolling an impact rolled gravel layer with thickness of 50cm in the base at a ground line, or forming a replaced gravel layer with thickness of 50cm through replacement, then filling a gravel layer with thickness of 30cm, excavating the side slope of the replaced gravel layer into a gradient of 1:0.5-1; laying a waterproof geotextile under the replaced gravel layer, at the slope toe of which a drain pipe is disposed; employing layered spreading rolling for earth filling above the gravel layer; and conducting strict levelling at a place of 30cm below a pavement structure layer, and laying an XPS plate thermal insulation layer. The method of the invention can effectively standardize and guarantee the construction quality of an insulating regulation subgrade, reduce heat absorption of an underlying bed in a subgrade body, reduce high subgrade induced highway diseases, reduce thawing of a permafrost subgrade as well as its nonuniform deformation, reduce the influence of climate warming and human engineering activities on permafrost subgrade characteristics, and improves the security and stability of subgrade structures.

Description

technical field [0001] The invention relates to a construction method of expressway subgrade, in particular to a construction method of heat insulation regulation subgrade of expressway in permafrost regions. Background technique [0002] The construction of roads in permafrost areas in my country began in the 1950s. Due to the lack of understanding of permafrost and its engineering prevention measures in the early stage, when encountering permafrost road sections, the usual method of dredging and filling in swampy areas As a result, large areas of permafrost were exposed and thawed, leading to hidden dangers of freezing damage in future projects. From 1972 to 1985, in order to improve the driving conditions of the Qinghai-Tibet Highway, the roadbed was widened and the road surface was blackened and reconstructed on the permafrost section. However, due to the strong heat absorption effect of the black road surface, the temperature of the road surface rises sharply, the accu...

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Problems solved by technology

However, due to the strong heat absorption effect of the black road surface, the temperature of the road surface rises sharply, the accumulated temperature of the underlying soil layer under the black road surface increases, the upper limit of permafrost soil moves down, the number of high-temperature frozen soil road sections increases day by day, and road diseases intensify, resulting in Part of the roadbed, road surface, and bridges and culverts were destroyed prematurely; at the same time, because the asphalt pavement blocked the water and heat exchange between the underlying soil layer and the outside world, the heat consumption of the water evaporation on the road surface was reduced, which caused the temperature of the permafrost under the roadbed to rise and seasonal The melting depth increases, and the underground ice near the original natural upper limit melts, which eventually leads to subsidence and deformation of the roadbed, damage to the road surface, and seriously affects the normal operation of traffic

Since the 1990s, some road sections have been raised to protect permafrost, and the original road diseases have been cured to a certain extent. However, in the permafrost section under plateau environmental conditions, the huge difference in heat absorption between the yin and yang slopes of high embankments and embankments has caused yang The artificial upper limit of the roadbed on the slope side is lowered, and the longitudinal cracks of the roadbed on the sunny side are caused, and the longitudinal asymmetric deformation of the roadbed is intensified

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