For the sediment of stake tip which were exceeded the range of criterion provided, this article put forward techigue of applies metathesis method in dealing with the sediment on stake tip, It can overcome low intesity of shortcomings of traditional hand method, also avoid harmful consequence of time limit for the construction, high cost as span handling.

In order to study the cooling effect of the closed ballast layer on permafrost on the Tibetan Plateau,a test field with a closed ballast pit and a gravel surface was built near the Beiluhe test site of the Qinghai-Tibet Railway,and the ground temperatures beneath the test field have been monitored.