Application and progress of soil nailing retaining technology in China

The application and progress of the soil nailing technology in China are decribed.The soil nailing technology has made new and great success.Especially the vertical and horizontal pre-stressed soil nailing retaining can be used in ultra-deep foundation pits and soft clay pits.The composite soil nailing has become a simple,inexpensive and widely-used support technology.At the same time the theoretical calculation has also made new development.The incremental method helps to study the mechanical mechanism of soil nailing retaining and makes us know that the force of soil nails is related to the construction process,so that it also helps to make reasonable calculation of the simplified method.Some accidents in soil nailing pits show that it’s necessary to pay attention to the non-circular sliding stability of the soft interlayers.It should be noted that the anti-pulling force is included in sliding region and stable region generally when detecting the soil nailing force.But the designed soil nailing force is only from the stable region.The displacement calculation of soil nailing walls is studied,and an elastic simplified method is put forward.Some new types of soil nailing retaining such as the micro piles combining with soil nails are proposed.Finally,there is a simplified idea about the stability calculation of soil nailing: checking soil-nail force in the horizontal direction and the safety of the bearing capacity of soils in the vertical direction.This method will be improved by geotechnical engineers who are engaged in the studies on soil nailing types and theoretical computation.