| With the continuous development of reform and opening up and urbanization,static piles are widely used in foundation treatment because of their characteristics of no noise,no vibration and no impact.However,hydrostatic pile sinking will produce crowding effect and cause uneven settlement of foundation,which will lead to serious damage to the building and surrounding environment,resulting in huge loss of human and material resources.Since the development of drainage consolidation method and hydrostatic pile sinking method in the last century,their theories and design methods have been developed relatively mature,but each has its own shortcomings,so the two can be applied in combination to achieve the purpose of comprehensive management of the foundation to reduce the crowding effect.The method has been applied in some projects,but there is a lack of in-depth research on its treatment effect,mechanism of action and design optimization.On the basis of domestic and foreign research,combining with the soil information of a proposed project in Xinzheng City,Henan Province,the change state of soil around the pile is studied and analyzed through the theory of circular hole expansion,so as to obtain the curves of displacement,stress and super-hole pressure with radial distance;then based on PLAXIS3 D software,the finite element method is adopted to consider the intrinsic structure model,pile-soil interaction,etc.,and the finite element method is applied to a)hydrostatic Then,based on PLAXIS 3D software,the finite element method was used to refine the numerical simulation of a)the penetration process of a single pile b)the sinking and consolidation of a hydrostatic pile after considering the factors of plastic drainage board,and to analyze and study the mechanism of its action.The results obtained are as follows:(1)Based on the classical circular hole expansion theory,the squeezing effect of the hydrostatic pile is analyzed,and the radial stress,radial displacement and super-hole pressure of the soil around the pile are decayed in a logarithmic form with the increase of the radial distance;the circumferential stress is first compressed with the increase of the radial distance,and then gradually turns to tensile and finally tends to zero.(2)The finite element software PLAXIS 3D was used to simulate the process of hydrostatic monopile sinking to obtain the distribution law curves of stress field,displacement field and super pore water pressure in the soil around the pile.It is shown that the displacement,stress and pore pressure of the soil near the pile side change significantly during the pile sinking process due to the "dragging" phenomenon,and the magnitude is related to the penetration depth of the pile and the distance from the pile.Finally,when compared with the theoretical calculation curves,the variation trends of the two are in good agreement,thus verifying the applicability of the model and the applicability of the theory of circular hole expansion to the calculation of the crowding effect of the pile body except for the shallow surface and the pile end.(3)The finite element software PLAXIS 3D was used to simulate the construction process of plastic drainage sheet combined with static pile sinking,and the regular curves of super-hole pressure and displacement with radial distance within the soil around the pile under different conditions were plotted by changing three factors of plastic drainage sheet arrangement,depth and spacing.It shows that the plastic drainage board can discharge the excess pore water inside the soil during the sinking process,thus improving the shear strength,accelerating the foundation settlement and shortening the consolidation time,and each influencing factor acts in different ranges inside the soil.Therefore,the advantages of the above three factors can be taken into consideration and combined to provide useful reference and design a reasonable construction plan during the construction of hydrostatic piles. |
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