Experimental Study On Bearing Behavior Of Lime Soil Non-Compacted Pile Composite Foundation

Lime soil compaction pile composite foundation is widely used in the treatment of collapsible loess foundation in our country,but because of the formation of loess structure for a long time,when the water content is too low will cause the structural strength of loess is large,resulting in compaction pile treatment to eliminate requirements of collapsible loess foundation is not reached,the lime pile non-compaction composite foundation study on bearing capacity in order to solve this problem in this paper.In order to study the influence of age strength on the bearing capacity of the lime soil non-compaction pile composite foundation,pile and soil complex with different ages were designed respectively and one dimensional compression test of pile and soil complex was carried out by means of consolidation compression apparatus;in order to study the influence of replacement ratio on the bearing capacity of the lime soil non-compaction pile composite foundation,pile and soil complex with different replacement rates and non compaction lime soil pile composite foundation model with different replacement ratio were designed,one dimensional compression test was carried out by means of consolidation compression apparatus and the model experiment was carried out by means of a self-designed indoor model loading device,the main conclusions are as follows:When the age strength of the lime-soil is increased,the composite modulus will increase,the settlement will reduce,the effective replacement rate will decreases,and the bearing capacity of the lime soil non-compaction pile composite foundation isimproved effectively;when the replacement ratio of lime soil pile is increased,the bearing capacity of the lime soil non-compaction pile composite foundation will improve,the stress of pile body and pile-soil stress ratio will reduce;before it is soaked by water,the pile-soil stress ratio and the load sharing ratio will decreased with the increase of the load level;after it is soaked by water,the pile-soil stress ratio and the load sharing ratio will increase first then became stable,and will increase suddenly before the failure and load sharing ratio will reach 99%;after it is soaked by water,when the stress of soil between piles is greater than initial collapse pressure,the stress of soil between piles will transfer to the pile body,when the stress of soil between piles is less than or equal to the initial collapse pressure,the stress can be stable for a period of time,then,the pile stress is reversed and the pile stress is transferred to the soil between piles;under the condition of lime soil pile end bearing,the failure of the lime soil non-compaction pile composite foundation is the failure of the pile and the strength and deformation of the pile determine the bearing capacity of the lime soil non-compaction pile composite foundation;for the first time,the standard values of negative friction under different replacement rates are given and it is suitable for pile foundation and the lime soil non-compaction pile composite foundation;according to the failure model,the safety factor is calculated according to the material strength formula Fs=2.635,and it is suggested to increase the strength of the pile head,and to set up the gravel cushion,the soil between piles should be treated with water.