Reliability Study Of Composite Soil Nailing Foundation Pit

On the base of soil nailing structure，as a new kind of retaining and protecting structurefor foundation excavation, composite retaining protecting structure has got rapid developmentin the recent years. According to the site conditions, this technology combines soil nailingwall with deep-mixed pile, jet grouted pile, mini pile, steel-tube soil nail or prestressed anchor,thus forms a composite retaining and protecting structure for foundation excavation,thistechnology overcomes the flaw of traditional soil nail supporting technology, namely can’tcontrol the deformation of slope, so it has many advantages, such as safety, reliability, lesscost, low time-consuming, and is gaining a wider and wider range of application. Therefore,it’s of great significance to develop the study of compound soil nail support technology’sstability and reliability.The text mainly analyses the stability of compound soil nail support and calculate thereliability index on the basis of Qingdao railway station’s foundation pit support engineering.Following is the main content:Simulate the compound soil nail support of this project by using FLAC3D, and confirmall kinds of index which are needed in the service of software. Simulate the process ofexcavation of foundation pit, research the meet between soil and rock bolt, soil nailing, theinfliction of prestress, etc. Discuss the influence that composite soil nailing generates to soildeformation under different circumstance on the basis of engineering example. By contrastingthe deformation under different circumstance, it is observed that composite soil nailing hasfavourable restraining effect to the deformation. By calculating, discuss the axial force of thepre-stressed anchor and soil nailing respectively, draw the changing curve and get the law.Research the change of the stability of foundation pit with the change of composite soilnailing’s parameter, discuss the principle and provide offer to the design of practicalengineering. Work out the calculation procedure of Matlab on the basis of genetic algorithm,calculate the reliability of Qingdao railway station’s foundation pit support engineering;Change the design parameter of pre-stressed anchor and soil nailing, calculate correspondingreliability index, and get the change rule of reliability index with the change of parameters.