Design and application of anti damage for the first row of boreholes by grouting in separation layer of overlying strata
Dong Kaifei
Abstract：To prevent damage to grouting boreholes caused by overburden movement,a smaller-diameter tubing is typically run inside the technical casing as the grouting pipe.Adopting this measure is merely a passive prevention approach,and it severely restricts the de-livery of grout,contradicting the requirement for a large amount of grout injection during initial grouting.If the initial grouting volume fails to meet the requirement of"supporting the key stratum by compressing and supporting the upper part"of isolation wall and grou-ting filling body,it will cause the sliding or deformation instability of"voussoir beam"block of the key stratum.If the overlying strata continue to move,the boreholes will be damaged,ultimately leading to the failure of stowing project.Based on the theories of"voussoir beam"as the key layer for overlying strata separation grouting,"four zones"in the strike direction,and strata movement angles,a de-sign method for preventing damage to the first row of boreholes during strata separation grouting was proposed using directional drilling technology,and has been applied on-site.Practical application has proven that this design not only meets the requirement of a large ini-tial grouting volume for the first row of boreholes,but also shifts from passive prevention to active control,eliminating potential safety hazards.This design can also be applied to the last row of grouting boreholes outside the working face cut and to the"isolated island"type of first and last row grouting holes in the middle.
Keywords：first row of boreholesanti damagepassive preventionactive preventiontechnical parameters of hole body
Publication Date：2025-12-30
Online Publishing Date：2026-01-31(First online date of this platform, not the publication date of the document)
Pages：5( 12-16 )