Study On The Stability Of Saturated Tailing Sand Foundation Which Treated By Soil-cement Mixing Pile

Cement soil mixing pile composite foundation is regarded as one of the major method of foundation treatment,which has received more and more widely application due to its convenient construction and low cost properties.Currently,studies on the cement soil mixing pile composite foundation are common in the treatment of rigid foundation,which has a relatively perfect theory system and design method.However,theory is still not mature enough for the flexible foundation with cement soil mixing pile composite foundation, especially treatment techniques of the saturated tailing sand special foundation is few in China.With the accelerating pace of the modernization construction in our country,highway route is inevitable to through all kinds of complex terrain.In the mining area,we often encounter problems such as through the tailing reservoir.Therefore,it is necessary to analyze the force-deformation of saturated tailing sand treated with cement soil mixing pile.In this paper,we know the basic physical and mechanical properties of saturated tailing,and basic properties of model pile by the laboratory test.At the same time,according to the similarity theory and the actual engineering,we conduct laboratory model test of cement soil mixing pile composite foundation treating saturated tailing sand.In the process of experiment,we buried displacement meter、pore pressure meter、earth pressure cell,and pasted strain gauge on the pile.After five times loading and draining,a total of six stage tests, we analyzed and recorded the vertical settlement、pore water pressure、inter-pile earth pressure and changes of pile strain of the cement soil mixing pile composite foundation,and then further calculated the pile-soil stress ratio, axial force of pile shaft, side friction of pile and pile side frictional resistance strength.The model test results indicated that: when using cement soil mixing pile composite foundation to treat saturated tailing sand settlement: In the loading stage, the surface soil bearing more stress, the axial force of pile damping along the depth direction. with the increasing of load level, the stress in the bottom of the pile is increased, pile side friction’s maximum positions move down, and the nearer from the center the greater the force is; In the drainage stage, because of the soil has the large scale consolidation, the load move to the pile top, cause the pile soil stress ratio increases, the soil pressure reduces, the axial force of pile increases, near the pile head appeared negative friction resistance. According to the result of model test, we can find that cement soil mixing pile treatment of saturated tailing sand has a good effect, but the discharge cause a great influence on the stress and deformation of the composite foundation.