Research On In-situ Stress Measurement And Application Based On Inelastic Strain Recovery

The ASR method is developed based on the directional core,which can measure the three-dimensional in-situ stress measurement method of near-in-situ in-situ stress state.As long as the directional core can be obtained,the experiment can be carried out.Theoretically,it is not limited by the drilling depth and temperature.It is not restricted by on-site measurement conditions and has wider applicability.Based on a systematic review of the development history of in-situ stress testing methods at home and abroad,this paper compares and analyzes the advantages,disadvantages,and applicability of several currently widely used in-situ stress testing methods.The research status,basic theoretical basis,basic testing process,data processing,and development of test equipment for ASR in-situ stress testing methods are introduced in detail.The ASR in-situ stress test method was applied for the first time in the near-horizontal deep borehole of a new Sichuan-Tibet railway to carry out in-situ stress measurement,and the inelastic strain recovery compliance study was conducted in the laboratory on the same core that collected inelastic strain recovery And temperature calibration.The inelastic strain recovery compliance experiment was carried out using uniaxial long-term loading and biaxial long-term loading experiments.The experimental results showed that the near-horizontal exploration hole of a new Sichuan-Tibet railway tunnel fell within the flexibility ratio range proposed by Matsuki.Combined with the inelastic strain recovery experiment in the laboratory,the in-situ stress state of 4 measuring points within the horizontal depth of 444.0 ~ 520.9m in a tunnel of the newly built Sichuan-Tibet Railway was obtained;the maximum principal stress was between 10.40 ~ 12.38 MPa,The intermediate principal stress is between 3.02 ~ 4.17 MPa,the minimum principal stress is between 2.64 ~ 3.64 MPa,the dominant direction of the largest principal stress is between NE63.08°~ NE81.33°,and the dominant direction of the largest principal stress is NE71.01°,consistent with the main direction of the Qinghai-Tibet Plateau tectonic stress field of the Chinese stress map.Finally,the factors and applicability that affect the reliability of the ASR in-situ stress test method are discussed.Based on its advantages of high measurement efficiency,low cost,and high measurement accuracy,it is expected that the ASR method will have great application prospects in deep scientific drilling,deep resource exploration,and major underground engineering projects.