The Suggestions and countermeasures of strengthening quality of soil nails
The technology of soil nails support for its "fast, active and effective" and other characteristics,has been widely used in coal mine roadway support.As with the depth of mine increasing, for cross section of roadway,the pressure from the safety of the roadway become more prominent, especially for frequent accidents, such as roof caving, morphology and the complexity of the mine pressure information, puts forward a new challenge for soil nails support technology.In order to ensure the safety of the mining, all kinds of factors that affect of roadway soil nails supporting technology will be analyzed, and constantly optimize and improve its performance from the technology, with the greatest degree to improve the stability of the mine development.
1 Control the material and performance index of soil nails
In the view of the influence factors of quality in soil nails supporting, different material, prestress value of soil nails, which corresponding different reinforcement effect, and it's different in the effect of preventing sliding and the tensile stress, generally speaking, select the corresponding materials and specifications should consistent with the nature of different mining depth and surrounding rock of roadway characteristics, , so as to better realize the roadway support, in this way,we can effective control of surrounding rock reinforcement.
2 The appropriate selection of soil nails torque force
Closely tied to torque increases with the soil nails pretensioned stress, from the point of research practice, the friction between the nut and screw in the soil nails support, when more than 400 n · m torque value, the prestressed relative increase slower, therefore, for the actual supporting , from the cost of anchor technology, technical precision up to choose the appropriate materials, to meet the torque value of 300-400 n · m reasonably require.
3 The deformation of soil nails make pressure performance boost
For deformation let pressure function, there are larger impact pressure on soil nails in the process of overload, bolt elongation improving is effective measure to reduce the deformation and fracture, especially between the nut and tray to increase spherical pressure tube, when let pressure pipe to obtain its value when pressure load, and make pressure pipe through own compressive deformation to realization of bolt elongation of ascension.
4 Strengthen the rational match of "the three paths"
For the stability of the soil nails support system, strengthen the reasonable matching of drilling, rod body and resin anchoring ,therefore forming a scientific and effective soil nails support parameter values, in order to realize the higher supporting effect of coal mine rock.Such as for rebar anchor rod body and the hole diameter should be controlled between 6 to 8 mm, and to ensure orderly in the process of installation, to increase the diameter of the resin anchoring value as far as possible, in order to achieve the best effect of stable soil nails support.
5 Ensure soil nails centered and force equilibrium
The fracture of soil nails is one of the important hidden trouble which affect the quality of the soil nails supporting，for the soil nails fracture caused by too much stress, especially the tensile or shear force is too concentrated, at some point to do this, from the high technology commonly used disc sex convex angle design, increase the contact area between the nut and tray, in the installation for resin anchoring agent and borehole axis, anchor center line uniformity is symmetrical, prevent unilateral stress concentration, to ensure the good stability of the soil nails supporting system.