The soil nailing retaining is widely used in China

but the principle and calculating method of soil nail are not so perfect. It is necessary carry out field test to consummate the theory of soil nailing. The testing includes horizontal displacement and soil nail tension etc. The distribution laws of deep excavation horizontal displacement and soil nails tensile forces are obtained through the field test. Some important conclusion are reached: I I I The maximum horizontal displacement occurs on the top of deep excavation; ( 2 ) Along whole depth of deep excavation

the maximum soil nail tensile forces occur in the range of middle depth; 1 3 I The maximum soil nail tensile force occurs in the middle range of soil nails along its length. The curve which is formed by positions of maximum tensile forces of soil nails may be the most dangerous sliding curve.