Application Of Multi-directional Mixing Cored Pile In Soft Foundation Treatment Project Of Fengnan Steel Works

A new soft soil foundation treatment technology multidirectional mixing cored pile is not widely applied and lack of practical experience.To develop in-depth research for it’s key technologies needs to combine with engineering applications.Taking the sotf soil foundation treatment project of Fengnan Steel Factory(located in Tangshan City,Hebei Province)as an example,this article evaluates the project’s quality by physical testing,appraising its key technical parameters and putting forward a technical proposal for further optimization through ANSYS finite element numerical simulation the basis of introducing the compariscon and selection of soft soil foundation treatment schems,the design and construction technology of multi-directional mixing cored piles.Fengnan Steel Factory are distributed typtcal soft soil foundation with characteristics of high water content,void ratio,compression,sensitivity but poor physical properties etc.multi-directional mixing cored pile can not only provide with enouhg bearing capacity,but fully play a role in strength of prestressed pipe pile.Fengnan Steel Factory project chooses Multi-directional mixig cored pile as reinforcement scheme of soft soil foundation,which has obvious rationality and superiority in terms of technology and economyThrough the numerical simulation of multi-directional mixing cored pile under working vertical load,it is found that in normal load,the lateral friction of pile can share more than 90%of the total loa,increasing the ratio of inner and outer core length which can effectively redue the settlement on the top of multi-directional mixing cored pile,the optimal ratio of inner and outer core length should be 0.75;the settlement on the top of multi-directional mixing cored pile can be decreased by increasing the ratio of inner and outer core length.As the ratio decreased,the optimum cross-section core content of multi-directional mixing cored pile should be 0.25,and for the cement oontent,it should be about 22%.To improve the strengh of cement-soil,the ash content of lower pile body can be increased appropriately,The results shows that the failure mode of pile group is determined by the pile’s ultimate bearing capacity,which is divided into side esistance failure and end resistance failure of pile group The main factors which influence group effect of multi-directional mixing cored pile are pile cao and pile spacing.Pile cap restricts the relative displacement of soil on pile group foundation and influence the pile body’s load transferring rule,resultin the imperfect lateral resistance value on pile body.The latetal resistance on pile body maximum value is different from the single pile on the top of the pile,but appears in middle and lower part of pile body.In pile group foundation,without considering the influence of pile length,as the increase of piles and decreas of pile space,the pile side resistance will be smaller and smaller,When the length ratio of inner and outer core piles is 0.75,the core ratio is 0.25,and the space of piles is 3m,the load bearing and economy effect is perfect.