Deformation Mechanism And Settlement Analysis Method Of The Gravel Pile Composite Ground Under Embankment

In order to improve the bearing capacity and resistance to settlement of softground,gravel pile composite ground came into being.Settlement calculationmethods of gravel pile composite ground are a lot.These methods assume that thepile and soil have the same strain,only considered the vertical compressivedeformation,ignoring the influence of radial deformation on the settlement of gravelpile.However,the assumption“the pile and soil have the same strain”is out of work inthe condition of pile piercing cushion upward.And there will be unignored radialbulging deformation under the load of soil.It can be seen that the settlement analysismethod of gravel pile composite ground can not simply apply the above methods.Thesettlement calculation method of gravel pile composite ground should consider thevertical compression and radial bulging deformation.Firstly,the composite ground is divided into two sections:bulging section andnon-bulging section based on the analysis of bearing capacity and resistance tosettlement.The method in this paper considers the bulging deformation can not beignored.A settlement analysis model for gravel pile composite ground is established.Then the radial deformation of bulging section is taken into consideration.Ananalytical model with typical pile-soil element is imported.The compressivedeformation analysis methods for bulging section and non-bulging section areestablished respectively.The substratum settlement is calculated by traditionallayered summation method.Therefore,a new settlement analysis method for gravelpile composite ground under embankment is put forward.As gravel pile composite ground often damages due to the bulging of pile,grillsleeve is muffled at the top of pile.Grill sleeve and gravel pile formsreinforced-hoop-gravel-pile composite ground.As a consequent,this paper analyzesthe settlement of reinforced-hoop-gravel-pile composite ground next.Firstly,themechanical mechanism of reinforced-hoop-gravel-pile composite ground underembankment is discussed with its engineering characteristics,the composite groundis divided into three sections:reinforced-hoop section,unreinforced-hoop section ofgravel-pile and the substratum section,then,a settlement analysis model ofreinforced-hoop-grave-pile composite ground is developed.Secondly,the pile-soilrelative slip of the reinforced-hoop section and the radial deformation(e.g. lateral displacement of gravel pile) of the unreinforced-hoop section are taken into account,an analytical model with typical pile-soil element is imported,and the compressivedeformation analysis methods of the reinforced-hoop and the unreinforced-hoopsection are set up respectively,therefore,a new settlement analysis method for thereinforced-hoop-gravel-pile composite ground under embankment is proposed.Finally,the settlement calculation and analysis of gravel pile composite groundand reinforced-hoop-gravel-pile composite ground are carried out by means of theproposed method and other existing analytical methods respectively.The analyticalresults are compared with the measured settlement values.It is shown that thisproposed method is reasonable and feasibile.