Analysis Of Work Mechanism And Stability On Soil Nailing Structure With Decompressive Platform

Soil nailing is a supporting technology with a soil nailing as the main force component of the slope. It consists of dense group of soil nailing, in–situ soil reinforced, concrete surface layer and the necessary water system.Meanwhile, in order to increase its performance of stability, decompression platform is frequently set in the supporting structure. It is a supporting structure of active force and by increasing the shear strength of soil to achieve the purpose of supporting. It is widely used in various projects of soil supporting for the advantages of fast and easy construction and economic reliability. However, in theory, the mechanism and stability of soil nailing has yet to arrive at a thorough analysis. It leads to the designer taking into account unreasonable importance of the factors during the design of soil nailing, and the design results is very different with the real situation.In this paper, using quasi-cohesion theory, on the basis of many previous studies of soil nailing structure, a new concept of decompression platform is put forward and on the shear strength of soil nailing an analysis in the improvement of the mechanism is studied. To the soil nailing structures that set decompression platform, the internal forces transmission of soil nailing where is up and below the platform is derived from the shear-lag method, and compared with the condition in which structure does not set platform. After analyzing the damage models based on the predecessors, combined with the monitoring data of actual project and field experience, a theory of crack-sliding and a potential multi-sliding pairs of linear damage model is put forward and its stability formula is derived. Finally, through monitoring horizontal displacement and soil nailing force of a structure, a result to the soil nailing structures which set platform that the horizontal displacement and soil nailing force change with the construction time and digging in depth is derived. Comparing the experimental result of soil nailing force, the result of the internal forces from the soil nailing formula is similar, and the point of the largest soil nailing forces is also near the potential fracture plane of the theoretical analysis. The results of this study provide a good reference value to the design and construction of soil nailing structure.