The Study On Working Performance Of Composite Soil Nailing Wall And Its Part Of The Basic Structure

The composite soil nailing wall is widely applied in all kinds of foundation pit supporting projects. But the research of its function mechanism is relatively lag behind. The latest specialized technical codes of composite soil nailing wall,"Technical code for composite soil nailing wall in retaining and protection of excavation", Provides a design method of soil nailing and pre-stressed anchor, It Consider the basic structures contribution to the overall stability of composite soil nailing wall, such as pre-stressed anchor, miniature pile, the curtain, but different form (structure) composite soil nailing wall structure of whole working mechanism and basic structure for the contribution of whole structure work is still not clear. On the engineering, engineers always see the outside the basic structure of the soil nailing as a safety reserve, Restricting its application and popularization. This paper’s research purpose is through the in-situ test and numerical analysis, to find out the whole work mechanism of composite soil nailing wall, and analyzes the basic structure of function and character.This paper based on in situ test of1:1, Through the foundation pit slope monitoring system of soil nail, bolt internal force, curtain and micro axial force and lateral pressure, vertical deep soil horizontal displacement and deformation.We mastered the mechanical properties of micro piles, pre-stressed anchor and soil nailing wall, the curtain in the excavation process, and get the working mechanism of composite soil nailing wall composed by soil nailed wall, pre-stressed anchor, miniature pile the curtain. By FLAC3D numerical experiments, and compares the field measurement. Base this, and through the virtual load or excavation, we get the failure modes of composite soil nailing wall structure which is commonly used. By analyzing the basic structure parameter sensitivity, find out the main effect of pre-stressed anchor, curtain, root pile in the composite soil nailing wall, Get the following conclusion for reference of engineering technicians:In the composite soil nailing wall structure system, the basic structure of the composite soil nailing wall Interact with each other, is an organic whole, pre-stressed anchor effective constraint deformation of foundation pit, and reduce the force of soil nail. Improve the pre-tension pre-stressed anchor, can enhance the effect, conducive to the overall stability; the curtain can not only check the water permeability, its soil retaining effect is significant. Curtain can effectively deformation foundation pit slope and its surrounding soil, and affect the destruction form of foundation pit. Curtain can effect the improvement of the soil nail force, Contains the curtain of composite soil nail axial force of soil nail wall is far less than that without the curtain. The role of root pile is not big, the influence on the deformation and stress distribution of composite soil nailing wall is limited, when the design can be ignored.