Abstract: Numerical simulation was used to obtain the stress path divisions of the soil surrounding the tunnel under excavation. Based on this, the influence of different stress paths on the change law of the surrounding soil strength index was studied. The results show that tunnel excavation can result in four different stress path divisions in the surrounding soil stratum. Different divisions have different influences on the tunnel stability and different stress paths have their respective damage forms. The same damage form (extrusion damage or compression damage) may have basically similar damage strength even if the different stress paths are different while different damage forms may have different damage strengths. Generally speaking, extrusion damage will have a damage strength 10%~25% lower than that of compression damage. The above research results have provided a strong basis for an accurate study of the influence of engineering properties of environmental soil strata.

Key words: Stress path, Tunnel, Triaxial test, FLAC, Construction disturbance