Simulation Study On Stress Deformation Of Mini Pile Prestressed Anchor Composite Soil Nailing Excavations Protection Structure

Mini pile prestressed anchor composite soil nailing structure is a new type of excavations retaining and protection technology that developed in recent years. Which has the characteristics of convenient construction, simple technique, short construction period and good economic benefits and so on. So it is widely used in deep excavations engineering.Mini pile prestressed anchor composite soil nailing structure is a composite retaining and protection system that is composed of three structures: soil nailing, prestressed anchor and mini pile with different working mechanism. Three structural units in the same retaining system, the interaction and the control process is complex. So the mini pile prestressed anchor composite soil nail wall retaining and protection structure in practical application has achieved success. But in the construction process, the interaction of soil nail prestressed anchor, mini pile and collaborative work mechanism and the structure members that respectively combined effect on the deformation of excavations is not very improve and perfect.In this paper, used ABAQUS finite element numerical analysis software, build soil nailing wall, prestressed anchor composite soil nailing wall, mini pile composite soil nailing wall and mini pile prestressed anchor composite soil nailing wall four kinds of finite element model. Analysed the retaining and protection structures effect on the stress and the deformation behavior of excavations in construction process and the interactional ruler of the three structures members in mini pile prestressed anchor composite soil nailing wall. The main research production as follows:1、The free end of pre-stressed anchor act on the surface layer, restricts the displacement of the side wall of excavations directly, and the both ends of free part pressed the soil, as a result the soil deformation, and changed the axial force of soil nails and the ground subsidence outside excavations.2、Mini piles improved the vertical compressive rigidity and horizontal flexural rigidity of the soil near by the lateral wall of excavations, limit the lateral displacement of the wall of the excavations and the ground subsidence out side excavations, made the axial force of soil nailing and pre-stressed anchor redistribute.3、Mini pile prestressed anchor composite soil nailing structure has both characteristics of mini pile and prestressed anchor. Reduced the deformation of excavations, reduced the maximum axial force soil nailing and made it redistributed, made the slip face antedisplacement, and enhanced the stability of the excavations.4、Compared with the soil nailing retaining and protection structure, pre-stressed anchor composite soil nailing retaining and protection structure, mini pile composite soil nailing retaining and protection structure, mini pile pre-stressed anchor composite soil nailing retaining and protection structure have some advantages: the deformation of excavations is the least, the axial force of soil nail is smaller, and the location of advantage slip surface is also the most front. It is a better retaining and protection structure form.