Study On Soil Nailing Walls Of Geotextile Facing

The shotcrete facing is often used as the facing of soil nailing walls and the facing of soil nailing walls is often assumed to be imposed on by the Rankine's active pressure,but it is only designed by constitution in engineering applications.Compared with the shotcrete facing of soil nailing walls,the paper studied on the soil nailing walls of geotextile facing which should substitude for the conventional facing layer of steel net plus shotcrete in soil nailing walls.In engineering applications,the shotcrete facing of soil nailing walls is also called flexible facing of soil nailing walls,so we call soil nailing walls of geotextile facing as flexible facing of soil nailing walls by relative.The theory about how nail-facing-soil interacte in soil nailing walls of geotextile facing is not researched sufficiently by now.Theory lags far behind practice.This article carried out the research from the following aspects: the model test method was used to simulate loading damage.FLAC3 D software was applied to simulate excavation support and loading damage.The formula of the earth pressure on surface is derived from the Culmann's formula.The tensile strength and burst strength of geotextiles used in the model test were measured.The horizontal displacement of geotextile facing is monitored in the engineering application.The main research conclusion of this paper are summarized as follows: the soil nailing plays an important role in the interaction between soil nailing and soil,such as tensile,bending and shearing;The axial force of soil nailing is big in the middle but is small at both ends,but compared with the active zone of the shotcrete facing soil nailing walls,the soil nail axial force of geotextile facing soil nailing walls shows much smaller;The potential sliding surface of the geotextile facing soil nailing walls has a tendency of backward expansion at the bottom of the foundation pit;In the process of vertical soil nailing wall excavation,the maximum horizontal displacement of the surface layer is located at the top of the foundation pit,while moved down when loading;At the end of excavation,the maximum soil nail axial force appears in the middle of geotextile facing soil nailing walls,while on the top of the pit when loading.The maximum soil nailing axial force of shotcrete facing soil nailing wall is always in the middle of the foundation pit;Based on the analysis of the pressure change under different mesh sizes,if we want to expand the application scope of geotextile but don't change the material in design,we must consider making changes on the mesh.Theory analysis shows that the bursting strength will become more bigger while the mesh size smaller;The conclusion is drawn that the supporting ability of geotextile is directly related to the grid spacing of the surface layer and the maximum depth of geotextile under the Rankine's active pressure can be 7m in the engineering application.