Experimental Study On The Reduction Of Expansion Of Pile-anchor Support System

In North China,Northeast China,Northwest China,Southwest China and other regions,winter accounts for one quarter or even half of the year,and more than half of the regions have seasonal frozen soil.The characteristics of the soil layer in the seasonal frozen soil area are that the winter freezes and melts in summer,and the freezing and melting directly reflect the frost heaving and melting.For the wintering temporary foundation pit support project and the permanent retaining wall constructed in the soil of the seasonal frozen soil area,the continuous freezing and thawing process will cause various problems in engineering performance and durability.Some of the existing anti-frosting measures,such as changing the soil layer or laying insulation materials,are not suitable for permanent retaining walls,therefore,in order to reduce the risk of frost heaving when frost heave occurs,it is necessary to use a measure of swell.Although a certain amount of bulging holes can be arranged in the frost heaving soil to reduce the frost heaving force,there is a water leakage problem when the bulging hole is laid,It is also unreasonable.Therefore,for this problem and the requirement that the retaining wall needs to be provided with a drain hole,a new idea of integrating the drain hole and the reducer hole is proposed.By setting a deformation joint on the drain pipe,the frost expansion force is reduced.To eliminate or mitigate the adverse effects of frost heaving.In this paper,the silty clay of Shenyang was selected,and the PVC pipe was selected as the material of the drainage reduction hole.Two parallel tests were designed,and the indoor freezing test was carried out.The main effects of the different stiffness of the PVC pipe of deep foundation pit on the frost heave effect are as follows:(1)Through the conventional geotechnical test,the basic physical indexes of the silty clay were determined,and the scheme of the frost heave response test of the PVC pipe was determined.(2)The firost heave response test of PVC drainage pipe was carried out,and the stress,strain and wall stress data of the pipe wall were monitored.Through the processing and analysis of the data,the strain and stress of the PVC pipe wall during the negative temperature freezing process and the normal temperature melting process were discussed in detail.The research in this paper is of great significance for the permanent slope engineering in seasonal frozen soil areas to eliminate the adverse effects of frost heaving.