地表荷载作用下长壁采空区覆岩结构失稳力学分析

Mechanical analysis of instability of overburden structure in goaf under surface load

  • 摘要: 为评价地表建(构)筑物荷载作用下长壁采空区覆岩的稳定性,借鉴“砌体梁”结构力学模型,基于采用布辛尼斯克公式解析解得到的附加应力在地基中传递的应力圆,提出了地表荷载作用下的采空区覆岩结构受力形式;基于矿山岩层控制理论中的“砌体梁”理论,利用“砌体梁”结构的关键块分析方法,建立了地表荷载作用下长壁采空区覆岩稳定性的关键岩块受力模型,推导了地表荷载作用下长壁采空区覆岩结构关键岩块受力计算公式;基于“砌体梁”结构关键岩块的S-R稳定理论,建立了地表荷载影响下长壁采空区覆岩中“砌体梁”结构的S-R稳定性判据模型,并推导了滑移和回转失稳判别公式。研究表明:地表荷载作用下长壁开采形成的采空区覆岩结构形式仍为“砌体梁”结构,地表荷载作用下采空区覆岩结构稳定性与地表荷载作用位置和大小,关键岩块深度、块度、回转角、承受荷载值以及岩块间摩擦因数等因素有关。采用新建立的地表荷载作用下采空区覆岩结构S-R稳定性判据模型,对某新建8层楼房受采煤影响的地基稳定性进行了评价,并与传统的附加应力法(利用地表荷载影响深度与覆岩破坏高度是否重叠来判定采空区覆岩稳定性)进行了对比分析,结果表明:地表荷载作用下采空区覆岩结构S-R稳定性判别法在基础数据充分的条件下更加精准。该评价方法通过分析地表工程建设地基中的附加应力作用于长壁采空区覆岩结构是否失稳,来判别采空区的稳定性,可定量分析地表荷载对采空区覆岩结构稳定性的影响,发展了传统的利用地表荷载影响深度与覆岩破坏高度是否重叠来判定采空区稳定性的半定量评价方法。

     

    Abstract: In order to evaluate the stability of the overburden in the long-wall goaf under the load of the surface structures, the “voussoir beam” structural mechanics model is used for reference, combined with the additional stress obtained by the analytical solution of the Boussinesq formula to be transferred in the foundation The stress circle of, and the stress form of the overburden structure in the goaf under the action of the surface load is put forward.Based on the voussoir beam theory in the mine rock strata control theory, using the key block analysis method of the “voussoir beam” structure, the force model of the key rock block for the stability of the overburden in the long-wall goaf under the action of the surface load is derived, and the calculation formula for the force of the key rock block of the overburden structure in the long-wall goaf under the action of the surface load is also got.Based on the S-R stability theory of the key rock of the “voussoir beam” structure, the S-R stability criterion model of the “voussoir beam” structure in the overburden of the long-wall goaf under the influence of surface loads is established, and the slip and rotation loss are also derived.It shows that the overburden structure of the goaf formed by longwall mining under surface load is still a “voussoir beam” structure.Under surface load, the stability of the overburden structure of the goaf and the position and size of the surface load, the key rock Factors such as block depth, lumpiness, rotation angle, bearing load value, and friction coefficient between rock blocks are related.Using the newly established S-R stability criterion model for the overburden structure of the goaf under the action of the surface load, the foundation stability of a new 8-storey building affected by coal mining was evaluated, and it was compared with the traditional additional stress method(using the depth of influence of surface load and the height of overburden failure are overlapped to determine the stability of the overburden in the goaf).The results show that the S-R stability determination method of the overburden in the goaf under the action of surface load is sufficient in basic data.It is more accurate under the conditions.This evaluation method judges the stability of the goaf by analyzing whether the additional stress in the foundation of the ground engineering construction acts on the overburden structure of the long-wall goaf to determine the stability of the goaf, and can quantitatively analyze the effect of surface loads on the stability of the overburden structure of the goaf.Therefore, a traditional semi-quantitative evaluation method has been developed to determine the stability of the goaf by using whether the depth of the impact of the surface load and the height of the overburden damage overlap.

     

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