EXCAVATION INFLUENTIAL SURFACE OF SOIL NAILING AND ITS APPLICATION IN ESTIMATING THE NAIL TENSILE FORCES

Based on the constructional feature of soil nailing, concepts defining a family of EIS——Excavation Influential Surface (the most likely slip surface when the latest excavation surface remains temporarily unsupported and the nails are not yet installed) and EEP——Excavation Earth Pressure (the earth pressure that the soil body from the concrete face to the EIS act on the retaining structure) are proposed. The EEP of (i1)th excavation phase subtracted from the ones of the ith phase gives the unbalanced forces during the ith construction step. The unbalanced forces will be balanced by the nails. And taking into consideration of the nails’ contribution to the slope stability, nail tensile forces will be induced. This paper focuses on the EIS and the method to calculate the soil nail forces where the simple linear wedge EIS is used. By means of the method, we can estimate the location and magnitude of the maximum nail tensile forces during construction. The calculated nail forces for Experiment 1 of CLOUTERRE Research Project by this method agree fairly well with the experiment data.