Evaluation method of ductility of grouted rock mass for advanced renovation of water-sand mixture inrush area

An evaluation method of ductility of a grouted rock stratum for advanced renovation of a water-sand mixture inrush prevention area, comprising following steps:

• Step 1, acquiring a spatial distribution law of cracks in overlying strata, establishing a three-dimensional geological model of the cracks in overlying strata including a crack width and a horizontal inclination angle, and establishing a grouted rock stratum unit geological model;
• Step 2, calculating rock stratum quality standard Q of a target rock stratum in the overlying strata according to an RQD index, a quantity of joints Jn, joint roughness Jr and a joint inclination angle α of each drill core of the target rock stratum by means of
• Q
• =
• 1
• N
• ⁢
• ∑
• i
• =
• 1
• N
• (
• RQD
• J
• n
• ⁢
• J
• r
• cos
• ⁢
• α
• )
• i
• wherein N is a quantity of boreholes in the target rock strata;
• Step 3, solidifying a grouting material to obtain a plurality of groups of grouting consolidated bodies, performing compression tests on the plurality of groups of grouting consolidated bodies, calculating a strain softening index Ds of each of the plurality of groups of grouted consolidated bodies, taking the strain softening index Ds as a parameter for evaluating ductility of each of the plurality of groups of grouted consolidated bodies, and obtaining an average value D′s of strain softening indexes Ds of the plurality of groups of grouted consolidated bodies;
• Step 4, grouting the grouting material into the target rock stratum, selecting a plurality of groups of grouted target rock in the grouted target rock stratum, calculating unstable fracture ductility KCS of each of the plurality of groups of grouted target rocks, taking the unstable fracture ductility KCS as a parameter for evaluating ductility of each of the plurality of groups of target rocks, and obtaining an average value KCS of the unstable fracture ductilities KCS of the plurality of groups of grouted target rock;
• Step 5, acquiring a permeability coefficient K1 of a grouted target rock stratum, and judging permeability strength Jw of the grouted target rock stratum;
• Step 6, calculating and obtaining an evaluation index R of ductility of the grouted target rock stratum, wherein a formula for calculating the evaluation index R is as follows:
• R
• =
• D
• s
• ′
• ⁢
• K
• c
• S
• ′
• QJ
• w
• determining a grade of the evaluation index R of ductility of the grouted target rock stratum according to a calculated value of the evaluation index R, wherein the evaluation index R of the ductility of the grouted target rock stratum is graded as follows:
• when a value range of calculated R is 0≤R<0.25, it indicates that the ductility of the grouted target rock stratum is very good;
• when a value range of calculated R is 0.25≤R<0.5, it indicates that the ductility of the grouted target rock stratum is good;
• when a value range of calculated R is 0.5≤R≤4.5, it indicates that the ductility of the grouted target rock stratum is poor;
• when a value range of calculated R is R>4.5, it indicates that the ductility of the grouted target rock stratum is very poor.