Abstract: This paper reports the design of an auxiliary shaft at a depth of more than 1 000 m at Cixi colliery and its surrounding geological conditions, and addresses the scheme for monitoring the in-situ stress around the shaft and the principle of inverse calculation for the in-situ geostress using the “Baoshen” analytical solution. The average values and nonuniform distribution of horizontal stresses are actually obtained at the depth of 1 208 m through inverse calculation and analysis of field monitoring data, which reveals that the ratio of horizontal stress to vertical stress conforms to the dead weight stress field. The lateral pressure coefficient ranges from 0.256 to 0.278. The in-situ stress distribution around the shaft is illustrated based on finite element simulations; and thus the reliability of inverse data based on field measurements is corroborated. Meanwhile, it is shown that the nonuniform distribution of horizontal stress is related to some factors such as the shear modulus of rock and geological tectonic, etc. With combining the information on tectonic evolution in this area and geomechanical principles, the consistence among the results of in-situ test, analytical solution and numerical simulations is comprehensively analyzed. In this context, the universality of the Hoek & Brown statistic principle about the distribution of horizontal in-situ stress is questioned, and the existing analytical methods for calculating the in-situ horizontal stress are also discussed, laying a foundation for using the “Baoshen” solution to the shaft lining design.

Key words: in-situ stress, shaft lining test, inverse calculation of in-situ stress, super deep shaft