Solid backfill coal mining technology can be safely and efficiently used to exploit coal resources under aquifers, without causing harm to the water resources and the environment. Nevertheless, the mechanism of fracture development and seepage channel or pathway control in the key aquiclude strata (KAS) in backfill coal mining under fluid–solid coupling have not been studied. Based on the similarity theory of fluid–solid coupling physical simulation, this study involves experimental evaluation of similar materials and characteristics of composite KAS, backfill body, and aquifer. Subsequently, we designed and employed three experimental models for physical simulation, corresponding to backfill materials’ compaction ratios (BMCRs) of 0%, 65%, and 80% using the geological conditions of mining face No. 101 under the aquifer in the Wugou coal mine. Fracture evolution laws, mining-induced deformation, and stress distribution characteristics of composite KAS with different BMCRs are studied. The backfill body can effectively weaken the influence of mining stress, such as the maximum subsidence, sinking speed, initial or periodic fracture damage area of the composite KAS, inhibiting the formation of seepage cracks and water inrush channels. The increase in the BMCR plays an important role in the closure and repair of developed fractures.

固体回填煤开采技术可以安全有效地用于开采含水层下的煤炭资源，而不会对水资源和环境造成损害。尽管如此，在流固耦合下回填煤开采的关键含水层（KAS）中裂缝发育和渗流通道或路径控制的机理尚未得到研究。基于流固耦合物理模拟的相似性理论，本研究涉及对类似材料和复合KAS，回填体和含水层特征进行实验评估。随后，我们设计并采用了三种物理模拟实验模型，分别利用五沟煤层中101采煤层的地质条件，分别将回填材料的压实率（BMCR）设置为0％，65％和80％。矿。研究了具有不同BMCR的复合材料KAS的断裂演化规律，采动变形和应力分布特征。回填体可以有效地削弱采矿应力的影响，例如最大沉降，下沉速度，复合KAS的初始或周期性裂缝破坏面积，抑制渗流裂缝和涌水通道的形成。BMCR的增加在闭合和修复已发展的骨折中起重要作用。抑制了渗流裂缝和涌水通道的形成。BMCR的增加在闭合和修复已发展的骨折中起重要作用。抑制了渗流裂缝和涌水通道的形成。BMCR的增加在闭合和修复已发展的骨折中起重要作用。