Abstract: The calculation principles in the measurement of in-situ stresses using the horizontal drilling hydraulic fracturing method are undefined. Therefore, a case study is conducted on a horizontal directional drilling survey project of the Tianshan Shengli tunnel. A theoretical model for the three-dimensional stress state of the surrounding rocks in horizontal boreholes is established on the basis of the native fissure and intersecting porous methods, and its controlling boundary conditions and computational methodologies are investigated. Subsequently, the rationality of the theoretical model is validated through comparative analysis with data from indoor physical model experiments. Finally, a finite element model for stress measurement using hydraulic fracturing in horizontal boreholes is constructed, and its feasibility is validated through comparative analyses of numerical simulations, theoretical calculations, and indoor experimental results. The findings are as follows: (1) The calculated results of the theoretical model closely align with the recorded data from the indoor physical model experiments, with a maximum discrepancy of 6.8%, indicating that the theoretical model for the stress state of surrounding rocks in horizontal boreholes, constructed by integrating the native fissure method and intersecting porous method, is applicable for stress calculations using hydraulic fracturing in surveys based on horizontal directional drilling. (2) The results of numerical simulations closely resemble the experimental records, with a maximum deviation of 9.51%, indicating that the use of the Abaqus extended finite element method combined with embedded cohesive elements can effectively simulate the measurement of stress induced by hydraulic fracturing in real horizontal boreholes. (3) The consistency between the calculated results of the theoretical model and numerical simulations is satisfactory, with the maximum error falling within an acceptable range. This validates the correctness, accuracy, and reliability of both the theoretical model and finite element simulation method.

Key words: horizontal directional drilling, hydraulic fracturing, in-situ stress measurement, numerical simulation