Research On Safety Exploiting Depth Of Mining Under Buildings

Starting from the concept of safety exploiting depth,the paper analyses the relationship among safety exploiting depth, mined thickness and the critical deformation of structures. Firstly, by analysing and calculating based on the measured strata of Pingdingshan 4th coal mine and chinese measured surface migration parameters, this thesis obtains a proper method for determination of safety exploiting depth, that plays an important guide role in determining whether some protective measures of underground mining and surface structures should be adopted or not, which also supplys the rule for decreasing resource wasting. Secondly, the article uses the FLAC^3D numeric simulation software to simulate, and synthetically analyses the results of numeric simulation. On the base of above rusults, the change rules of surface migration distortion values and migration parameters while the actual mining depth past or below the safety exploiting depth of mining under buildings are discovered, and the change rules of surface migration distortion values and migration parameters when the exploiting thickness is the same but the exploiting depth not or the exploiting depth is the same but the exploiting thickness not are also discovered. Thirdly, the paper shows that it is not simple linear relationship between the safety exploiting depth of mining under the buildings and coal bed exploiting thickness, because the safety exploiting coefficient reflects the rule of safety exploiting depth change following the exploiting thickness change, the safety exploiting depth increases following exploiting thickness, but the increase in amplitude decreases gradually. In addition, the thesis analyses influence factors of safety exploiting depth of mining under buildings, such as the exploiting thickness, the rock character, the method of mining and so on. Finally, through comparison of analyzing results of observation materrial and numeric simulation, this article confirms the safety exploiting depth exists while mining under buildings, and also shows that the safety mining depth even exists in different mining geological, but the values of safety mining depth are different.