Roof Separation Measure And Separate Interlayer In KuZiDong Mine 11-2

The stability of the roadway is mainly related with the roof abscission layer, and the roof abscission layer is divided into two categories, the plastic layer and the interlayer. The mechanism of two kinds of separation differently, and the support characteristic of them is also different. But we don’t distinguish between two kinds of separation in the project, we always use the total separation value to judge the stability of roadway, which brings serious hidden dangers in production. So it has practical significance for engineering practice to study the characteristics of roof separation and to separate the plastic layer and the interlayer from the total separation.This article has conducted the research to the roof abscission layer from the following several aspects:1.Through laboratory experiment, we test mechanical parameters of 11-2 top coal rock and determine the structure and stability of roof rock strata by taking the field roof rock core. 2.We take the engineering reality as a model, to simulate numerically on stress of roof by using the ANSYS software, to research characteristics of the stress distribution of the roof, and also to explore the normal tensile stress region. 3.In the light of the location of the normal tensile stress, we analyze measuring- point arrangement in the process of engineering measurement, and put forward the optimization scheme of measuring points. 4.We systematically analyze the deformation characteristics of the plastic layer and the interlayer, and get a method of separating out two kinds of separation on this basis. 5.We take use of multi-point displacement meter and roof abscission layer instrument for measurement of the engineering practice in coal mining area 11-2. After collecting the measured data of roof abscission layer, we separate total separation into the plastic layer and inter layer, and compare the total separation with the separation of abscission layer by list.The main conclusions are as follows:1. 11-2 coal roadway roof belongs to the typical composite roof, the integrity and mechanical properties of roof rock mass are both poor. As it has many structure plane and contains the weak interlayer, the roof stability is low and the supporting is very difficult.2. After excavation of roadway, the natural stress of rock mass balance is broken, the stress is redistributed, forming stress clusters around the roadway, which results in deformation of surrounding rock. The normal tensile stress between the layers above the roof is the main cause which leads to the roof separation. The normal tensile stress generally appears in the structural plane of rock mass, especially, it has the most widely distribution range and the biggest value in the weak intercalations place. In addition, between each layers, tensile stress value which is perpendicular to the tunnel center position is the biggest, and the tensile stress decreasesas as it moves on both sides.3. Selection of the measuring point location in Engineering measurement can produce a large effect on analysis of abscission layer. Combined with the feature of distribution of roof tensile stress, we know that the location of the roof which is most likely to be separated located in the weak interlayer and structure parts, so in the arrangement of measuring points, firstly, we observe the roof lithology to understand strata distribution roughly, and then preferentially arrange measuring points near the weak interlayer above the roof, followed by the various structural planes.4. At the beginning of the roof deformation, plastic delamination develops faster, at the same time, the attenuation of deformation speed is also fast; in the beginning of roadway mining shape variables of layer alienation are small, but its deformation speed attenuates slower, and maintains longer deformation time.On this basis,Ignoring the early deformation of roof abscission layer within 0~30 days, we take the number which is derived from the difference between the measured total roof abscission layer amount and the amount of 30 days as roof layer alienation values.Considering safety factor, we take use of measured roof abscission layer within 0~50 days as plastic delamination values.5. In view of Ku Zi Dong mine, we take the measurement of the engineering practice and separate the roof abscission layer.Through the borehole camera we validate the result of the separation, the results show that the judgment of roof stability is more realistic by separating the total roof abscission layer into the plastic layer and interlayer.The results of this study can provide technical reference for the determination of critical value of the roadway roof separation and the roadway supporting scheme selection.