Research On Floor Heave Mechanism Of Thick Seam Roadway In Wuyang Coal Mine And Its Control

At present, most of the control methods of floor heave are that the shallow cracked rock mass is reinforced or improving stress environment in other places, however, the stability of the middle-deep rock mass to the shallow is often neglected, especially the floor heave in thick seam. Under the double effects of great horizontal and disturbance stress, the failure characteristic of roadway floor is manifested as wide range and great depth, the single strengthening manner is far from effective in shallow rock mass. Therefore, according to the serious floor heave in special ventilation roadway in No.76mining area of Wuyang Mine, the deformation features and the deformation law of surrounding rock were analyzed by the double grouting support methods of the single shallow and the middle-deep, through engineering geological investigation, floor force state theoretical analysis, similar material simulation test and industrial test. The main results are as follows:(1) Floor mechanical model was established and the strain distributing disciplinarian calculated. The result shows that the tensile strain zero point was located at3.2m in the floor rock mass. Above3.2m, the shallow rock would be compressed by great horizontal stress; and under it, with the limit of the mobile spatial, the rock developed minimal deformation toward deep rock mass.(2) Cylindrical axial compression and tension strength tests were respectively carried out by using Elastic-Plastic and Strain Softening constitutive model, the result shows that the calculation result of Mohr-Coulomb failure criterion was inconsistent with laboratory test’s, which displayed a strengthening phenomenon before the stress peak. However, the calculation result of Strain Softening failure criterion was basically identical with laboratory test’s. At the preliminary stage of loading, the stress was increased as linear elastic feature, after stress peak, the specimen displayed a strain softening trait.(3) This paper proposed three different floor heave control methods, such as bolt-grouting support, U-shaped steel inverted-arch coupled with grouting support and the combined support of a branch of high-strength anchors coupled with concrete block and grouting support (ACBGS), and the stress field, displacement field and plastic zone was simulated by different control methods, the result shows that, the latter two methods can meet the need of engineering practice.(4) The distribution characteristics of grout capacity of the ACBGS show that grout capacity is proportional to the range of the cracked rock mass and reasonable grout amount of each hole can range from16.2m3to28.6m3in thick seam in No.76mining area, which can be taken for an example on similar engineering geological conditions.(5) Engineering test show that the relative displacement of the roadway’s sides is327mm, the floor heave is268mm, which are reduced by56.5and83.4%, respectively. Thus, the large-scale deformation of roadway floor on thick seam has been controlled effectively.