Investigation on Frost Damage and Water-Bearing Condition of Expressway Subgrade in Seasonally Frozen Soil Region

The lengthwise cracks caused by frost heave,and settlem ent, bulge, rut caused by spring thaw are the main forms of frost damage of roa ds in seasonally frozen soil region. The vast amount of field investigation data prove that gr oundwater is the most active and live factor causing roads to be frost damage. It not onl y attacks subgrade and aggravates its frost heaving, but also attacks frost-pro o f sand-gravel layer even subbase, and makes them lose the frost-proof function and the auxiliary bearing capacity, so that the frost boiling and damage of the roa ds ar ise in spring. The source of moisture is not just from vertical migration of gro undwater but also including the surface water supply from slopes of shoulders, d is abled drain ditches, cracks in pavements, median strips and so on, thus deterior ating the performance of subgrade and structural material.