Study On Two Key Problems Of Hollow Inclusion Gauge In Ground Stress Measurement

With the implementation of"13th Five-Year Plan"for transportation,construction of tunnels,high-speed railways,subways and other projects has been further developed,in order to carry out scientific and rational excavation design and construction of various rock projects,it is necessary to investigate the various factors affecting the stability of the project and learn more about the influencing factors of these projects.Through on-the-spot measurement and numerical analysis,it is possible to make economically safe and practical engineering design,the stress state in rock excavation engineering influence factors is one of the most important factors.This article is based on horizontal topic of ground stress measurement project of the dry mountain tunnel.Combining the development of borehole stress relief method?hollow inclusion strain gauge?,the in-situ stress measurement carry out with the method of a combination of indoor testing,theoretical analysis,and numerical simulation analysis.The analysis of the in-situ stress test of borehole stress relief method in the condition of near-field conditions and application effect of hollow inclusion strain gauge in jointed rock mass.There are mainly the following innovations and experimental conclusions:1.A method solving the vector formula of analytical solution of ground stress measurement of elastic superposition was used to propose borehole stress under near-field conditions based on the stress distribution formula near the borehole under the conditions of borehole radius r₁ and tunnel radius r₂.2.Based on the CSIRO hollow inclusion strain gauge and the KX-81hollow inclusion strain gauge,a hollow inclusion body strain gauge with two measuring points strains embedded in the same hollow body strain gauge barrel wall was designed and manufactured.two measuring points hollow body strain gauges can provide two sets of comparative data in a single measurement borehole,adjusting the distance of two measuring points before straining can analyze the stress state of two points at a time.The stress analysis of the jointed rock mass was performed using the measurement group's hollow inclusion body strain gauge.3.An indoor test of stress relief method for jointed rock mass was conducted on the condition of the core and the presence of joint surfaces in the rock mass during the drilling process in response to the borehole stress relief method for the core drilling stress fracture and rock joint surface conditions exist in drilling process of the lifting method,the two measuring points hollow inclusion strain gauge was applied to the in-situ stress measurement of the jointed rock mass,and the strain measurement value of two measuring points hollow inclusion strain gauge was compared with that of the borehole stress release process,and the strain value was measured.The stress distribution in the rock can be prepared and the error of the stress value between the loading process and the stress relief process is small.4.The application effect of drilling stress relief method?hollow inclusion strain gauge?in jointed rock mass and jointless rock mass was analyzed based on the model analysis of FLAC3D software.The stress value at the strain measurement of the hollow body during the stress release process was analyzed from the point of view of measuring point stress.