In this paper, the confirmed principle, means and mathematic model of capacity contract quantity, capacity contract price and efficiency displacement, bidding model, quote ways and mathematic model of bidding, and bargaining of timely market are investigated in detail.

But in China its research and application is just started and the improvement of transposing efficiency of the slurry is still a big problem yet to solve.

Due to differenf viewpoint, experience and the way of selecting parameters by different designers, different results were obtained in the calculation of displacement ratio "m", hence different pile length and number of piles are proposed.

With the changing of pile s length, displacement ratio and pile s strength,we concluded the settlement rules of semi -rigid-pile composite foundation by numerical calculation method.

Results show that, after CDMP treatment, the bearing capacity of the gravel layer with soft lens increases 63% with the replacement rate of 23%, and increases 15%―31% with the replacement rate of 11.

This paper brithe discusses the detednation of the bearing capedty of a single cement mixing-in-place pile in strengthening soft soil foundation, the relation between replacement rate and the capacity of composite foundation, the relation between the length of a pile and its sinking quantity as well as my own opedences in constructing cemat mixing-in place piles.