Study On The Deformation Characteristics Of The Pile Raft Foundation In The Positive And Oblique Filling Site

The differen settlement of ground is a main reason for the deformation and failure of foundation.especially in special rock and soil ground such as Cutting-filling soil,where foundating failure problems are prominent.Pile-raft foundation usually control different settlement.It is widely used in the foundation of the high buildings or soft foundation.In order to meet the need of project in Yan’an area,this paper dischsses the maximum extension in the pile-raft foundation under oblique intersection form,which can provide the basis for the ebgineering construction.The main research contents and research results of this paper are foillows:(1)According to the orthogonal crossing of pile raft foundation over the filling site,the deformation law of the foundation is obtained under different angle joint forms,The displacement and settlement of pile raft foundation has the characteristics of "large in the middle and small in the outside".With the crossing of the foundation to the filling side,the position of the maximum settlement gradually shifts to the filling area.The settlement of the foundation and the foundation soil at the second filling side of the second working condition meets the rule of "60 °> 45 °> 30 °" under the different angle combination surface.On the premise of meeting the allowable differential settlement,the maximum spanning distance of the foundation with different angle combination surface on the filling side has the characteristics of "30 ° = 45 ° > 60 °",and the pile pairs with larger than the allowable differential settlement are basically located between the outer side pile and the adjacent inner pile;(2)The deformation law of pile raft foundation is similar to that of orthogonal filling site in general under different angle joint forms.The maximum span of pile foundation with different angle combination surface on the filling side is characterized by "30 ° > 45 ° = 60 °",and the pile pairs with larger than allowable settlement difference are mainly concentrated between the x-direction side pile and the adjacent inner pile;(3)Based on the comparative analysis of the deformation law of the foundation crossing the filling area at skew and orthogonal,it is concluded that the crossing form of the foundation crossing the filling area at orthogonal is the most suitable,and the optimal span of the model at the filling side is 3m based on the engineering experience,which effectively increases the safety reserve of the foundation.In addition,from the angle and form of joint surface,pile raft foundation design and filling technology,the paper gives the controlsuggestions of differential settlement,so as to control the differential settlement of foundation across the filling site.