Prediction method for rock burst induced by working face lateral hard top plate
Technical Field
The invention belongs to the technical field of coal mining, and particularly relates to a method for predicting rock burst induced by a lateral hard top plate of a working face.
Background
The rock burst caused by the hard roof of the stope has a large specific gravity and is highly dangerous, and particularly when a hard suspended roof structure exists in the lateral direction of the working face, a strong rock burst disaster is caused to the gateway. The spatial structure of the suspended roof of the lateral roof has great complexity, so that great difference exists in stress field distribution of the gate way, and how to predict the impact ground pressure of the working face of the lateral hard roof is a great technical problem in coal mines. The prediction of the risk of rock burst under the condition is basically consistent with that of a common working surface, mainly comprises microseismic, a drilling cutting method, electromagnetic radiation, stress and the like, and has poor pertinence and reliability.
The lateral hard suspended roof structure of the working face can cause large static load when tunneling along an empty side tunnel, so that the danger during tunneling is serious, and the dynamic fracture effect of the working face top plate is added during mining, so that the danger is increased rapidly. At present, a roadway retaining technology is adopted, but due to the existence of a lateral suspended roof structure, a coal seam is subjected to the action of the whole process of lateral working face top plate movement, so that roadway wall caving and shortness pressing are serious, and local high stress is caused.
Until now, no specific and specific prediction method for the formation of the gate way aiming at the specific coal seam condition of the lateral hard suspended roof exists. Particularly under the condition of a suspended roof with a laterally hard roof, when the suspended roof structure generates unstable fracture motion, large-area and high-level impact energy is released, and the possibility of generating destructive rock burst is increased. When the coal seam has strong impact tendency, the size of the suspended ceiling is large, and the burial depth is large, the impact is induced by the fracture and the pressure of the top plate of the working face, the danger of the hard top plate type rock burst is difficult to quantitatively early warn by the conventional monitoring technology of the conventional method, and the static danger distribution caused by the suspended ceiling structure is difficult to predict in advance. Therefore, the prediction of the risk of gateway impact pressure under the condition of a lateral hard roof plate has not been an effective prediction technology so far.
Disclosure of Invention
Technical problem to be solved
The invention aims to provide a lateral trending dynamic subsidence observation method aiming at the situation that the impact danger of a roadway is difficult to predict under the condition that a hard suspended roof exists laterally.
(II) technical scheme
In order to achieve the purpose, the invention is realized by the following technical scheme: a method for predicting the impact ground pressure induced by a working face to a hard top plate, comprising the following steps:
step one, quantifying a suspended ceiling structure: firstly, clearing a roadway top and bottom plate, observing the top and bottom, and adopting an equal-spacing fixed-point observation suspended roof structure method, wherein the spacing is 10-12 m; monitoring and determining the size of the lateral suspended roof;
secondly, monitoring the trend of the lateral top plate movement: under the condition of lateral suspended roof, the impact dangerous area is closely related to the suspended roof motion, the suspended roof fracture motion is gradually increased along the mining direction, the impact danger caused by future roof motion can be judged by observing the trend motion intensity, the roof subsidence change can be monitored along the coal seam tendency, the mining side is larger than the coal pillar side, and the area with high roof subsidence speed and without being influenced by mining is the area with high impact danger,
the invention has the positive effects that:
1. the structural quantitative observation is carried out on the lateral suspended ceiling, the spatial structure characteristics of the lateral top plate under the static state are determined qualitatively, and the pre-judgment function for determining the impact risk is achieved in advance;
2. aiming at the top plate movement tendency characteristic of the side suspended ceiling type rock burst, observing the sinking amount of the roadway top plate along the tendency, and judging the side top plate tendency movement induced impact risk;
3. and (4) acquiring an impact dangerous area caused by the movement trend of the lateral top plate under the static condition of the roadway by comparing and observing the sinking speeds of the top plate in the key dangerous area, and carrying out early warning on the intensity of impact danger.
Drawings
Fig. 1 is a schematic diagram of a lateral suspended roof structure, fig. 2 is a schematic diagram of dynamic monitoring of a roof plate, and fig. 3 is a schematic diagram of a roof plate subsidence comparison curve.
Detailed Description
The embodiment of the invention provides a method for predicting rock burst induced by a working face lateral hard top plate, which comprises the following steps:
firstly, observing a lateral suspended ceiling at a distance of 10-12 m; the drilling detection technology is adopted to carry out quantitative detection on the suspended roofs below 5m and above, which is shown in figure 1;
secondly, performing trend observation on lateral roof movement on the qualitative dangerous area, and acquiring roof movement characteristics along the trend by adopting a same section comparison observation scheme, wherein 1 and 2 are roof dynamic instruments which are shown in figure 2;
and thirdly, carrying out contrast observation on the areas with obvious movement trends of the lateral top plate to obtain a top plate subsidence related curve, judging the impact danger degree according to the curve form, wherein 1, 2 are dangerous, and 3 is not dangerous, as shown in figure 3.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.