Research on Plastic Zone Evolution Law of Surrounding Rock of Gob-Side Entry Retaining under Typical Roof Conditions in Deep Mine

Abstract

To solve the control problem of the surrounding rock of gob-side entry retaining under typical roof conditions in deep mines, we conduct theoretical analysis, numerical simulation, and actual measurements. Starting from the plastic zone of the surrounding rock, the serious damage area, the degree and scope of damage, and the dynamic evolution process of the surrounding rock of the gob-side entry retaining are systematically analyzed under four typical roof conditions in deep mines; the expansion and evolution laws of the plastic zone of the surrounding rock are expounded; and a key control technology is proposed. The results indicate that (1) the plastic failure of surrounding rock was concentrated mainly on the coal side and on the floor, especially in the filling body. The plastic zone of the surrounding rock of the gob-side entry retaining with the thick immediate roof was widely distributed and deep, but the plastic failure of the filling body was not obvious. The plastic failure of the surrounding rock of the gob-side entry retaining with the compound roof was mainly concentrated on the roof, filling body, and floor of the filling area. (2) According to the typical roof conditions of the deep gob-side entry retaining, the order of the degree of damage to the surrounding rock was as follows: thick immediate roof, compound roof, thin immediate roof, and thick-hard roof. (3) A “multisupport structure” control system is proposed for the gob-side entry retaining in a deep mine, including measures for enhancing the bearing performance of the anchorage system, increasing the strength of the cataclastic coal-rock mass, enhancing the bearing capacity of the filling body, and increasing the bearing capacity on the tunnel side. The proposed technology was applied to the deep gob-side entry retaining project in the east area of Panyi Mine, and it effectively fulfilled the reuse requirements of gob-side entry retaining in deep mines.

Research on Control Mechanism of Surrounding Rock of Deep Gob-Side Entry Retaining

“…The deformation and failure of support structures in gobside entry retaining are uneven, which causes the overall instability of the structure due to the significant deformation and a part failure [18,19]. Based on the results of field investigations and simulation tests on the deformation and failure of the surrounding rock in gob-side entry retaining (Figure 6), the following conclusions are drawn: the support structure of the surrounding rock is first destroyed at the edge of the goaf and then toward the solid coal side.…”

Evolutionary law and regulatory technology of roof migration on gob-side entry retaining

“…Lu Shiliang 14 analyzed the fracture and collapse characteristics of the roof in the goaf in the gob-side entry and the force characteristics of the gob-side entry; Qin 15 analyzed the stress distribution law on the gob-side entry retaining and made a clear explanation for the phenomenon of high-stress “nucleation” in the advancing process of the working face; Liu 16 investigated the influence of the close coal seam roadway through numerical simulation and on-site monitoring. Liu 16 investigated the roof damage mechanism of the gob-side entry retaining in the close coal seam through numerical simulation and on-site monitoring; Wu 17 systematically analyzed the damage area, damage degree and range, and the dynamic evolution process of the rock on the gob-side entry retaining under four typical roof conditions in the mines from the peripheral rock plasticity zone; Xu 18 adopted a particle flow model to study the fracture evolution of the rock in the process of the fracture of the overlying roof in the gob-side entry, and the stress and porosity; Gao Yongge 19 used a particle flow model to study the fracture evolution of rock in the process of fracture of the overlying roof on the gob-side entry and the stress and porosity of rock. porosity; Gao Yongge 19 monitored the degree of roof slab fragmentation and delamination of the roof slab in the primary and secondary mining respectively; because the gob-side entry retaining is located at the edge of the mining zone, the stability of the surrounding rock of the roadway has a close relationship with the roof activity law, the current roof control technology of the gob-side entry is based on the theory of masonry beams 20 – 22 , the theory of the cantilever beams 23 – 26 and so on to establish the roof mechanical model and the stress distribution characteristics 21 , and the roof mechanical model 22 .…”

Study on the Deformation Mechanism of the Bottom Plate along the Empty Lane of Deep Mining and the Control Technology of the Bottom Drum

“…The fractured rock mass then undergoes postpeak creep under the action of mining stress during primary and secondary mining [8,9]. The deformation force and deformation speed of the square bottom plate in front of the primary recovery work are small, and the deformation of the bottom plate behind the working surface is violent, and the bottom drum volume is larger [10,11]; the deformation of the square bottom plate in front of the secondary recovery work is violent, and the bottom drum volume is larger [12,13]. At this time, the roadway surrounding rock must be regarded as a whole, and the control of the bottom plate must be placed in the same important position as the top gang control, and the reinforcement of the bottom plate must be carried out while supporting the top gang, so that the entire roadway forms an overall bearing structure [14,15].…”