Graded plugging, monitoring and reinforcing integrated method for separation stratum grouting under single-side open conditions

A graded plugging, monitoring and reinforcing integrated method for separation stratum grouting under single-side open conditions, comprising the following steps:

• S1. analyzing the development law of a separation stratum, and determining the scope of protective coal pillars for a surface building/structure;
• S2. constructing a combined plugging dam to prevent grout from flowing and migrating towards the remaining space of a target separation stratum above a mined area during separation stratum grouting under single-side open conditions, comprising the following specific steps:
• constructing three rows of dam grouting holes at a surface above the boundary of the protective coal pillar along the advancement direction of a coal mining face, with a periodic movement step distance of a target key stratum as a drilling spacing, firstly injecting first-grade grout into first-grade dam grouting holes, then injecting second-grade grout into second-grade dam grouting holes, and finally injecting third-grade grout into third-grade dam grouting holes;
• S3. monitoring and evaluating the combined plugging dam;
• and
• S4. determining whether there is grout leakage in the combined plugging dam, if there is, performing local reinforcement on the combined plugging dam, and otherwise, requiring no local reinforcement;
• wherein the separation stratum grouting under single-side open conditions refers to a partial separation stratum grouting and filling technique, involving that holes for separation stratum grouting are first drilled at a certain position ahead of the advancement direction of a coal mining face to a stop-mining line area;
• wherein the periodic movement step distance of a target key stratum refers to the advancement length of the coal mining face after the target key stratum is periodically fractured;
• wherein the first-grade dam grouting holes, the second-grade dam grouting holes and the third-grade dam grouting holes respectively refer to one of three kinds of grouting holes used for injecting grout into a separation stratum space below the target key stratum to construct a combined plugging dam during construction on a surface of the coal mining face, and the first-grade grout, the second-grade grout, and the third-grade grout refer to three kinds of grouts that correspond to the first-grade dam grouting holes, the second-grade dam grouting holes and the third-grade dam grouting holes, respectively;
• wherein in S1, the analyzing the development law of a separation stratum, and determining the scope of protective coal pillars for a surface building/structure comprises the following steps:
• determining burial depth of coal stratum, scope of mining area, and mining height data according to relevant geological data;
• studying rock stratum movement characteristics, analyzing the development law of an overlying separation stratum, and clarifying grouting separation stratum horizon, whether the separation stratum is closed, and whether the key stratum is fractured by combining physical simulation, numerical simulation, a mechanical model, an equilibrium condition and a constitutive equation in mathematics;
• obtaining the periodic movement step distance of the target key stratum and a movement angle of rock stratum under the condition of separation stratum grouting according to the rock stratum movement characteristics and the development law of overlying separation stratum;
• and determining the boundary of protective coal pillars for the surface building/structure according to the obtained movement angle of rock stratum and a rock stratum thickness.