Highway Subbase Weak Ground Stability Research

Baotou Airport Expressway is a brunch of Dan-La national Road for connecting Baotou Airport. It is a major project of Baotou City, lying at the suburbs of Baotou, with length of 5.7km and 4 lanes. It is designed according to driving speed of 100km/h.The ground under Baotou Airport Expressway is the bed of the old Huanghe River. The overburden layer is alluvial deposit with a main component of silty sand and silty fine sand, in which there is a 10m-20m thick layer of soil easy to liquidate.The ground bearing capacity is low because of the typical weak earth. How to strengthen this weak ground is the key of ensuring the project to be constructed successfully and to have a long service life and a good quality.After rounded analysis and calculation, this article puts forward the following methods according to the actual condition (e.g.: the distribution of soft soil and the height of embankment, and so on )to strengthen the soft foundation .The test observation indicates these methods not only are easy to be carried out but also have a low cost and a good effectiveness1) Replacing soft layer with soil containing crushed stone if the thickness of soft soil is less than 2m without hard crust.2) Applying sand mat and geogrid if the thickness of soft soil is between 2m and 5m, and the settlement during the service term is less than 20cm.3) Conducting the same method as just above if the thickness of soft soil greater than or equal to 5m with a 5m thick hard crust and the height of embankment is less than 3.5m, while the settlement during the service term is expected to be less than 20cm.4) Still using sand mat and gergrid if the thickness of soft soil greater than 5m, and the settlement during the service term is less than 20cm.5) Tipping stone rubble to displace the muck for the part of the road which passes...