Following unified standard for reliability of hydraulic structures(GB 50199-94) and based on a large number of data obtained in China and abroad , this paper presents the statistical character of resisting force parameter of sluice on soil foundation , abstracts the bearing capacity limit state expression of stability agai.

Soil foundation can be very significant to the Crashworthiness of the guardrail ,the stiffness of the guardrail will reduce when the soil foundation can not meet the requirements, and this will weaken the protection of the gardrail because of the larger lateral deflection when impact accident happends.

The actual earth subgrade resilient modulus is related with safety and economy of highway structure.

CBR test outdoor is a method of determining earth subgrade strength,which can t be regarded as a basic of designing.

For the construction readiness,technology and main points,the paper introduced the application of chemical churning pile to strengthening earth subgrade.

Classification on Subgrade Strength Grades of Semi?rigid Base Coarse for Sinkang High?grade Highway;

Study the performance of subgrade infiltration,bearing capacity and resisting frost of base.

By introduction to the relation of subgrade rebound modulus,rebound deflection and CBR at spot,the paper discussed its goal,sense,method and influenced factors.

Considerations on resilient modulus of earth foundation;