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综合机械化单元密实充填采煤充填体强度确定

Method and verification of strength determination for dense filling coal mining filling body in comprehensive mechanized unit

  • 摘要: 综合机械化单元密实充填采煤技术兼具岩层移动控制和固废处置的功能,且具有采充平行、工艺灵活、投资较少等优势,充填体强度合理设计关系承载效果和经济效益,但仍缺乏针对性科学依据。以三轮采充为例,理论分析得出综合机械化单元密实充填采煤工作面呈现“煤柱−充填体”分轮转移承载特征,可分为“煤柱全面承载”“充填体参与承载”和“充填体全面承载”3个阶段,并根据朗肯土压力理论得出了支巷充填体三向受力状态侧压力计算公式;根据等价采高和地表水平变形计算公式推导建立了充填体弹性模量与地表水平变形最大值之间的关系;实验室实验得出单轴抗压强度1~5 MPa的9组膏体试块在三轴围压p=0,0.5,1.0,1.5 MPa条件下的弹性模量,建立了充填体单轴抗压强度与三轴条件下弹性模量的关系。由此建立了基于地表水平变形指标的充填体单轴抗压强度计算式。以某矿浅埋深特厚煤层51106首采面为工程背景建立数值模型,研究表明前两轮采充后工作面“煤柱−充填体”上方垂直应力曲线呈陡峭的波浪状分布,地表下沉和水平变形轻微,第3轮采充后该应力曲线呈平缓的波浪状,地表下沉和水平变形明显增加,验证了“煤柱−充填体”分轮转移承载特征,同时,数值模拟和工程实践表明充填体单轴抗压强度确定方法是合理和准确的,可为综合机械化单元密实充填采煤工作面充填体强度设计提供参考。

     

    Abstract: The comprehensive mechanized unit dense filling coal mining technology combines the functions of rock movement control and solid waste disposal, and has advantages such as parallel mining and filling, flexible process, and low investment. The reasonable design of filling body strength is related to bearing effect and economic benefits, but there is still a lack of targeted scientific basis. Taking three rounds of mining and filling as an example, theoretical analysis shows that the comprehensive mechanized unit dense filling coal mining face presents a "coal pillar filling body" phased transfer bearing characteristic, which can be divided into three stages: "coal pillar comprehensive bearing", "filling body participating in bearing", and "filling body comprehensive bearing". Based on the Rankine earth pressure theory, the calculation formula for the lateral pressure of the filling body in the three directions of the support roadway is obtained; The relationship between the elastic modulus of the filling material and the maximum horizontal deformation of the surface was derived and established based on the equivalent mining height and the calculation formula for surface horizontal deformation; The laboratory experiment obtained the elastic modulus of 9 sets of paste specimens with uniaxial compressive strength of 1-5 MPa under triaxial confining pressures of 0, 0.5 MPa, 1.0 MPa, and 1.5 MPa, respectively. The relationship between the uniaxial compressive strength of the filling material and the elastic modulus under triaxial conditions was established. Thus, a calculation formula for the uniaxial compressive strength of the filling material based on the surface horizontal deformation index was established. A numerical model was established based on the first mining face of the 51106 shallow buried and thick coal seam in a certain mine. The study showed that the vertical stress curve above the "coal pillar filling body" of the working face showed a steep wave like distribution after the first two rounds of mining and filling, with slight surface subsidence and horizontal deformation. After the third round of mining and filling, the stress curve showed a gentle wave like shape, with a significant increase in surface subsidence and horizontal deformation. This verified the characteristic of the "coal pillar filling body" transfer bearing in stages. At the same time, numerical simulation and engineering practice showed that the method for determining the uniaxial compressive strength of the filling body is reasonable and accurate, which can provide reference for the strength design of the filling body of the comprehensive mechanized unit dense filling coal mining working face.

     

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