Method for detecting stress state of roadway surrounding rocks based on three-dimensional electric potential response

A method for detecting stress state of roadway surrounding rocks based on three-dimensional electric potential response, comprising steps of:

• S1:
• using a roadway space with a length of S along a roadway direction from an front end of a mining face as a detection area, selecting several roadway construction sections in the detection area, drilling boreholes in roadway surrounding rocks into a roof, two roadway side walls, and a floor in each roadway construction section, wherein at least two boreholes are drilled in each of said roof, two roadway side walls and floor;
• S2:
• obtaining an electric potential measurement surface through amplification of a roadway contour electric potential measurement around the roadway by a proportionality coefficient δi, using intersection lines of the electric potential measurement surface and the roadway construction sections as electric potential measurement lines, determining a distance Li between the i-th electric potential measurement line and the roadway contour, disposing positive electrodes at intersection positions of the boreholes and the electric potential measurement lines, and using positions of the positive electrodes as electric potential measurement points;
• S3:
• disposing a common negative electrode in the roadway, collecting electric potential data in real time comprising electric potential differences between the positive electrodes and the common negative electrode, and storing the electric potential data and three-dimensional coordinates of the electric potential measurement points in the boreholes and roadway surrounding geological information in an analysis computer;
• S4:
• digitally flattening the roadway contour to expand into a plane along a side line of the roadway in the roadway direction, extrapolating the electric potential measurement lines into horizontal lines arranged in sequence from low to high, scaling down the roadway contour into a digital model according to an equal proportion principle, and positioning position coordinates of the boreholes and the electric potential measurement points on the model;
• S5:
• performing spatial interpolation on all the electric potential measurement points to obtain a three-dimensional electric potential imaging volume, extracting three-dimensional abnormal electric potentials from the three-dimensional electric potential imaging volume and drawing a three-dimensional abnormal electric potential isosurface model wherein abnormal electric potentials are identified using an electric potential abnormality threshold evaluation method;
• S6:
• performing unilateral inversion tomogram imaging outside a borehole area through the electric potential measurement points on the electric potential measurement line at the highest position, to obtain an electric potential inversion plane nephogram, which divides a space outside the boreholes into several cuboid spaces, and using a radial basis function surface interpolation method to draw a three-dimensional abnormal electric potential inversion probability isosurface model;
• S7:
• visualizing electric potential distribution spatial characteristics of the roadway surrounding rocks using a three-dimensional electric potential response digital model, which is composed of the three-dimensional abnormal electric potential isosurface model and the three-dimensional abnormal electric potential inversion probability isosurface model, by displaying a spatial range, direction and development trend of a stress abnormal zone, thus allowing identification and determination of a stress state of the roadway and an abnormal electric potential response area.