Research On Application Of Cememt Fcy-ash Gravel Pile In High-grade Highway Soft Foundation Treatment

With the rapid development of our national economy and the improvement of people’sliving standard, the highway construction quality requirements are increasingly high. In order toadapt to the new situation and requirements, new materials, equipment, methods and processescontinue to emerge in highway construction. The soft foundation in high grade highwayreinforced cement fly-ash gravel pile composite foundation is a new soft foundation treatmentmethod. Although many scholars and engineering and technical personnel have carried out a lotof work in this area and even made many useful achievements, there are still many problemswhich need further study and exploration, because of the shortage of application, coupled withthe complexity and diversity. On the basis of previous research results, this paper carries outsystematic research on the application of cement fly-ash gravel pile in soft foundation treatmentof high grade in the highway from the aspects of design, construction, field test and effect test,according to the characteristics of high-grade highway soft foundation treatment, combinedwith the example of high engineering soft foundation treatment in BangNing highway. Themain work is as follows:It analyses the function of mattress layer on the cement fly ash gravel pile compositesubgrade, and gives the calculation method of the thickness of cushion. Based on theoreticalanalysis and engineering practice, it puts forward the calculation method of the designparameters of cement fly-ash gravel pile and mattress layer and the way to gain variousparameters. By means of the comparison and evaluation of the variously existing calculationmethod, it gives the bearing capacity and settlement calculation formula fitting for thecomposite foundation of cement fly-ash gravel pile and determines the range of the keyparameters in the formula.It proposes the construction technology to reduce or avoid quality problems. On the basisof summing up the common quality problem of composite foundation of cement fly ash gravelpile on, it gives concrete methods to solve problems and treatment approaches, as well as thequality control method and the corresponding detection means.Combined with the engineering background, it explains how the design parameters aregiven and the methods to determine the parameters. On the basis of the surface settlement inconstruction period and operation period and the analysis of horizontal displacement measureddata in construction, it conducts the calculation of the settlement prediction of final settlementand the settlement after the construction in practical engineering by using the exponential curvemethod （three points method） and the hyperbolic point matching method.Research results not only contribute to seek more reasonable design method of cementfly-ash gravel pile composite foundation, but also provide a reference and guidance for similarengineering problems.