沿空留巷底鼓力学模型及控制机理研究

Floor heave is one of the main forms of surrounding rock deformation in gob-side entry retaining. Because of the non-harmonious surrounding rock and the mining effect of two adjacent working faces, the loading condition of the floor in gob-side entry retaining is significantly different from a soft rock entry or other dynamic pressure entries, and there are great differences in mechanism of floor heave. Moreover, comparing with traditional control method of floor heave including strengthening method, destressing method and digging floor method, steel row piles method has an advantage on control of floor heave in gob side entry retaining. However, the control mechanism of steel row piles method remains unclear. So some investigations into the mechanical model and control mechanism by steel row piles method of floor heave will be carried out embarking on mechanism of floor heave in gob-side entry retaining in this project. Main contents are as follows:(1) The mechanical characteristics of the floor including loading distribution, stress evolution and deformation failure will be analyzed from excavation to scrap, especially during the first mining period, relative stable period after the first mining and the second mining period. This can provide reliable data for the establishment of mechanical model of floor heave in gob-side entry retaining. (2) The mechanism of floor heave in gob-side entry retaining will be revealed based on the deformation rule of rock under loading and unloading, the main influence factors and their effect of the floor heave and the frontal mechanical characteristics of floor. Then the mechanical model of floor heave in gob-side entry retaining will be established. (3) The interaction between steel row piles and the floor strata in gob-side entry retaining will be analyzed. Furthermore, the control mechanism of steel row piles method to floor heave will be revealed. The research results can further enrich the control theory of surrounding rock stability in gob-side entry retaining.

底鼓是沿空留巷围岩变形的主要形式之一。由于围岩的非均称性及受相邻两个工作面的采动影响，沿空留巷底板受载情况与软岩巷道和其他动压巷道显著不同，底鼓机理存在较大差异。并且，较之传统的加固法、卸压法和卧底法，钢排桩法在控制沿空留巷底鼓中具有一定优势，但其控制机理尚不明确。因此，本项目从沿空留巷底鼓机理着手，开展底鼓力学模型和钢排桩法对底鼓控制机理研究。主要内容包括：（1）分析沿空留巷从掘进至报废尤其一次采动影响期、一次采动后相对稳定期及二次采动影响期底板受载分布、应力演化和变形破坏等力学特征，为建立沿空留巷底鼓力学模型提供可靠数据；（2）研究岩石加卸载变形规律，分析沿空留巷底鼓的主要影响因素及其效应，结合沿空留巷底板力学特征，揭示沿空留巷底鼓机理，建立底鼓力学模型；（3）分析钢排桩与沿空留巷底板岩层的相互作用，揭示钢排桩法对沿空留巷底鼓的控制机理。研究成果可进一步丰富沿空留巷围岩稳定控制理论。

底鼓是沿空留巷围岩变形的主要形式之一，严重制约着沿空留巷技术的发展。目前对于沿空留巷底鼓机理仍没有定论，底鼓控制方法的机理尚不明确。本项目主要探究了沿空留巷的底鼓规律，研究沿空留巷底鼓机理并建立底鼓力学模型，进一步揭示底鼓控制方法的原理。主要研究成果：（1）底板岩石变形主要是峰后碎胀和峰后蠕变，底鼓主要是采动应力作用下底板岩石发生的峰后蠕变变形，主要发生在一次采动影响期。（2）揭示了沿空留巷围岩应力演化规律，分析底板受力特征，探究沿空留巷底鼓机理，初步建立底鼓力学模型。（3）钢排桩法控制底鼓是利用刚性承载结构在桩后形成附加应力场和应力拱，降低底板岩体主应力差，改善底板岩体受力环境，降低底鼓量。研究成果不仅丰富了沿空留巷围岩控制理论，更有效的推动了沿空留巷技术的推广和应用，取得良好的经济效益。