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Conditions causing frost heaving and frost boiling of soil foundation 1) soil quality; 2) hydrology; 3) climate; 4) driving; 5) maintenance of subgrade thawing and sinking phenomenon uneven frost heaving and road frost boiling phenomenon in permafrost region road frost boiling phenomenon in permafrost region groundwater frost boiling disease in low-lying areas, where the water is difficult to discharge and the groundwater level is deep and shallow, the filling height of subgrade is high When it is not large, the water content of soil increases due to groundwater recharge during freezing period, which causes road frost boiling in spring (Fig
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Figure 1: the high groundwater level under the low embankment is in the excavation and half fill and half cut sections in hilly or mountainous areas
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Improve pavement structure layer (1) lay sand (gravel) cushion layer (2) lay cement stabilized, lime stabilized or lime industrial waste base (cushion) layer (3) set antifreeze layer (4) lay thermal insulation layer, lay geotextile insulation layer on the top surface, and treat maintenance workers People treat boiling.
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Do well in subgrade drainage and raise subgrade 2
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Figure 2: excavated subgrade under high groundwater level figure 3: half excavated and half filled subgrade cuts off the filling embankment with aquifer on the hillside
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Set up blind ditch on shoulder or seepage ditch, set up blind ditch under side ditch schematic diagram, set up trench drainage longitudinal gravel blind ditch 4
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When the top surface of the subgrade is close to the groundwater level due to the excavation (Figure 2) or the cutting slope cuts off the aquifer (Figure 3) and the drainage is not smooth, road frost boiling occurs in spring
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Fig
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Frost heaving of subgrade is caused in winter and frost boiling occurs in spring, which is generally called two rib frost boiling
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4: treatment of filling pressure on aquifer outcrop and frost boiling 1
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During the spring thawing period, due to the excessive water content of the soil foundation, the strength of the soil foundation decreases sharply, and the effect of repeated driving, the spring, bulge, crack, slurry, rutting and other phenomena of the subgrade occur, which is called frost boiling
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Lay isolation layer (1) permeable isolation layer coarse-grained permeable isolation layer in permafrost area improve subgrade filling height set gravel and gravel isolation layer set gravel and gravel isolation layer (2) impermeable isolation layer ① spray asphalt directly; ② asphalt soil or asphalt sand; ③ asphalt felt or plastic film (4) composite geomembrane
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(3) Precautions: ① the isolation layer is suitable for both old and new roads, especially for new roads; ② the impermeable isolation layer is suitable for the impermeable subgrade, and only the permeable isolation layer can be set under the permeable subgrade
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Sometimes, it presses the aquifer or spring to make water seep into the subgrade (Figure 4)
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Sometimes, the water content of subgrade increases due to underground pipeline leakage, which will lead to road frost boiling
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Causes 2
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