Pie-Anchor Support And Optimization Analysis Of Deep Foundation In Silt Soil Area

With the 13th Five Year Plan put forward,the development of town construction in our countrysteps into a new stage.High buildings in cities and towns,subways and large municipal infrastructure are emerging,which makes the town construction land more tense,and then causes the sharp increase in the number of deep foundation pit engineering.pile anchor supporting structure because of its strong adaptability,small construction operation and the advantages of deformation control ability is highly appreciated by super large deep foundation pit engineering,so the research on the pile anchor supporting structure of deep foundation pits is also full of significance.To develop and utilize the underground space reasonably is an effective way to solve the shortage of land in cities and towns,for example,the construction of large parking lot,subways and other use have achieved quick results.However,the foundation pit supporting design has a strong district feature,the conventional foundation pit design concept and method can not give a foundation pit supporting scheme which is both safe and economic,and makes the deep foundation pit accident often happen,or it increases resources investments blindly for the foundation pit safety which greatly reduces economic benefits.So with the advancements in science and technology,three-dimensional numerical simulation for foundation pit design plays an irreplaceable role.This paper introduces the pile anchor supporting structure in detail,taking Kai Feng Song Dou Yin foundation pit supporting project as an example,which uses ABAQUS finite element software to do a numerical analysis in the project and a detailed analysis in the aspect of the surface settlement,the foundation pit supporting pile body horizontal displacement,bending moment of pile and anchor the changing rule of the axial force comparing with the measured data analysis,which proves that the support scheme design is safe,but not to maximize economic benefits.Therefore,this paper also optimizes the simulation analysis of anchor cable in the horizontal spacing,free section,anchor length and anchor cable Angle,and draw the following conclusions:(1)The horizontal spacing of anchor cable in 1.5~2.2 meters for the foundation pit engineering, its deformation can meet the specification requirements,and foundation pit supporting and surrounding buildings are also relatively safe and stable.At the same time with the increase of anchor spacing,it can also help to avoid the generation of group anchor effect,and prevent the overall destruction in foundation pit engineering.(2)The free segment of anchor cable and ordinary anchorage of anchor cable length do the appropriate adjustments of 1 meter,which can not only ensure the stability of supporting structure,but also can greatly save material and then makes the project expense reduce.For the calculation model of this paper,under the same conditions,the consumption of three rows of anchor cable can save about 6 meters after it is optimized.(3)When the anchor Angle of anchor cable increases from 15~0 to 30~0,the maximum bending moment of pile increases,but it doesn’t make big difference of the supporting structure and deformation.So considering the convenience of the anchor cable expanding body construction,the avoiding of the expanding body section grouting body of precipitation and bleeding,and the requirement in"regulations of technology of high pressure jet expanding head bolt",it proves that the anchor Angle of anchor cable for30~0 is reasonable and feasible.