Laboratory model tests and finite eleent analysis of soil nails-anchors supporting technique of foundation pit excavation

The composite supporting technology of soil nailing and bolting was developed from soil nailing technology; this technology is simple in construction, short construction period, low cost and has some other unique advantages. Although it has been widely used in engineering, but the theory of the composite supporting system is still imperfect and needs to be improved. Therefore it is essential to carry out model tests to deepen the knowledge of the composite system of soil nails and anchors. Through multiple sets of model tests, the internal force distribution of soil nailing, foundation soil displacement field are obtained in different loading locations and different construction stages. The effect of the support has been evaluated. The results show that: if there is a large additional load very close to the pit slope, a straight line sliding surface is prone to occur; otherwise, usually occurs a arc-shaped one. Soil anchors is very effective to prevent the slip surface occur through the slope, so if the additional load is close to the slope, anchors should be arranged in the middle and upper positions of the slope; if the addtional load is far from the slope, anchors should be arranged in the lower position instead.