Small-angle cross tunnel construction method

The invention discloses a small-angle cross tunnel construction method. The small-angle cross tunnel construction method comprises the following steps: step one, digging a crossing section of an uppertunnel after the upper tunnel is constructed to the crossing section, and carrying out preliminary support of the crossing section of the upper tunnel; step two, constructing supporting piles downwards at intervals from the upper tunnel, wherein the supporting piles comprise second supporting piles located in the crossing section of the lower tunnel and first supporting piles located at two sidesof the crossing section of the lower tunnel; step three, carrying out secondary lining of the crossing section of the upper tunnel; step four, carrying out advanced support of the crossing section ofthe lower tunnel after secondary lining concrete of the crossing section of the upper tunnel reaches design strength; and step five, digging the crossing section of the lower tunnel, successively cutting pile bodies of the sec