Stability Evaluation of Small Coal Mine Goaf Site under Engineering Construction Conditions
With the increasingly prominent problems such as the destruction of land resources in mining areas and the shortage of land for urbanization construction,it is inevitable to build buildings above the goaf. The poor foundation formed in the goaf of small coal mines has a significant impact on engineering construction,and it is particularly important to evaluate its stability. Firstly,the AHP method was used to analyze the main influencing factors on the stability of small coal mine goaf under engineering construction conditions,and then the evaluation method was studied from the perspective of mechanical analysis. The results indicate that the stability of small coal mine goaf under engineering construction conditions is mainly affected by the buried depth of the goaf,building loads,and the safety and stability of coal-rock pillars. To calculate the safety and stability coefficient of coal-rock pillars under engineering construction conditions,additional loads caused by building structures were added on the basis of the recommended formula in the original specifications,and a new calculation formula was derived. When evaluating the stability of the foundation,the existing formula is modified to consider that the buried depth of the roadway roof should be the distance from the foundation bottom to the roadway roof rather than the distance from the ground to the roadway roof. The equivalent internal friction angle should be used instead of the internal friction angle,and the upper load should be based on the foundation pressure rather than additional stress. At the same time,for ease of use,a formula for calculating the safety and stability factor of the overlying strata is added. The actual case proves that the modified method for determining the critical depth of load influence is suitable for evaluating the stability of small coal mine goaf. Compared with the uncorrected formula,it not only achieves safety and reliability,but also avoids being too conservative and increasing the cost of foundation treatment.
engineering constructionstability evaluation of foundationsmall coal mine goafAHPmechanical analytical method
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