Study On Anti-mining Deformation Performance Of Rigid Pile Composite Foundation

The mining of underground coal mining face causes the deformation of the upper soil,and when the upper part is a rigid pile composite foundation,it will also be disturbed.In order to put forward the design method of rigid pile composite foundation engineering in mining area,this paper studies the variation law of mechanical properties parameters of rigid pile composite foundation before and after mining disturbance through indoor triaxial test and numerical simulation,and finally gives the recommended reduction value of bearing capacity characteristic value of rigid pile composite foundation in mining area.The main results are as follows:(1)The disturbance reduces the strength parameters of composite foundation,but the pile body does not destroy.The reduction of the strength parameters of composite foundation is caused by the reduction of the strength parameters of soil between piles.The lateral unloading disturbance reduces the equivalent cohesion and the equivalent internal friction angle of composite foundation with rigid piles by about 10%.The lateral loading disturbance reduces the equivalent cohesion of composite foundation with rigid piles by 5%.Within this range,the effect on the equivalent internal friction angle is small.(2)Rigid pile composite foundation has good anti-mining deformation performance,and increases with the improvement of the mechanical properties of foundation soil.When the bearing capacity of composite foundation reaches 600 kPa,the strength parameters of composite foundation are reduced below 5%after disturbance.(3)When the bearing capacity of composite foundation in mining area is high,rigid pile composite foundation is preferred.Based on the research results,the reduction coefficient of the characteristic value of bearing capacity of composite foundation with rigid pile in mining area is proposed.When the bearing capacity of composite foundation with rigid pile is greater than 600 kPa,it can not be reduced.When the bearing capacity of composite foundation with rigid pile is greater than 450 kPa and less than 600 kPa,the reduction coefficient is 0.95,and when the bearing capacity is less than 450 kPa kPa,the reduction coefficient is 0.90.The coefficient is reduced.The paper has a total of 117 pictures,40 tables,and 111 references.