为实现瓦斯抽采钻孔漏气裂隙的有效动态封堵，防止负压驱动下浆液在裂隙中漏失，以羧甲基纤维素钠（SCMC）与钠基膨润土（Bent）为主料，通过引入系列添加剂制备了SCMC-Bent基封孔水凝胶，并测试了该水凝胶黏度的演化过程。然后通过开展负压作用下的浆液运移实验，研究了SCMC-Bent基水凝胶在煤颗粒间裂隙网中的运移及漏失特性。最后测试了SCMC-Bent基封孔水凝胶pH演化过程，采用傅里叶变换红外光谱（FTIR）、扫描电镜（SEM）及X射线衍射（XRD）表征了其微观结构，进而揭示SCMC-Bent基水凝胶黏度演化的微观机制。研究表明：①在恒温条件下，SCMC-Bent基水凝胶的黏度随时间呈现“先上升、后降低” 趋势；水料比越大，SCMC-Bent基水凝胶的黏度越低、越早发生后期黏度下降。②水料比越高的水凝胶在裂隙网络中运移越快，但负压作用下却越早发生漏失；相较其他水料比，水料比10∶1的水凝胶在负压抽气第24天仅运移41 mm，更容易长时间密封漏气裂隙。③ SCMC-Bent基水凝胶内部的蒙脱石层结构随时间先增多后减少，存在中间产物（SCMC-CXP）插入蒙脱石层间的现象，SCMC-CXP插入量随时间先增多后减少并随水料比增大而减少；蒙脱石层与层间SCMC-CXP形成了类似“三明治”的夹层结构，在水凝胶体系中逐渐形成了由蒙脱石层、层间SCMC-CXP、层外SCMC-CXP组成的三维网络。④三维网络结构的形成是造成SCMC-Bent基水凝胶黏度前期升高的原因；但随时间持续，中蒙脱石层结构减少且SCMC-CXP大分子链断裂，导致了三维网络结构消散进而致使水凝胶黏度降低；另一方面，高水料比削弱了SCMC-CXP在蒙脱石层间的插入量及大分子间的相互作用、增强了三维网络结构的过水能力，进而导致水凝胶黏度下降。

To achieve the effective dynamic sealing of fractures inducing air-leakage around gas extraction borehole and to prevent slurry loss from fractures under negative suction pressure, SCMC-Bent based hydrogel was prepared, which is composed of sodium carboxymethyl cellulose (SCMC), sodium bentonite (Bent) and other additives. Herein, viscosity evolution processes of the SCMC-Bent based hydrogels with different water-material ratios were measured in laboratory. Then, migration and loss properties of the SCMC-Bent based hydrogel in fracture net work of coal grains were studied by the slurry migration experiment under negative suction pressure. Finally, pH evolution of the gel was measured, and micro-structures of SCMC-Bent based hydrogels with different water-material ratios and isolating-standing times were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-ray diffraction (XRD), aiming to illuminate the micro mechanism of viscosity evolution. Study results show: ① at a constant temperature, the viscosity of the SCMC-Bent based hydrogel presents the trend of “rise first, and then drop” over time. The higher the water-material ratio, the lower the viscosity of the SCMC-Bent based hydrogel, and the earlier of the time corresponding to the viscosity dropping. ② The higher the water-material ratio, the faster the hydrogel migrating in fracture net, but the earlier the hydrogel loss happening under the negative pressure. Compared to the hydrogels with other water-material ratios, the hydrogel with water-material ratio of 10:1 merely migrates 41 mm after 24 days under negative pressure, indicating that it is more easily to block fractures with air leakage for a long time. ③ The number of montmorillonite layers in the SCMC-Bent based hydrogel increases first and then decreases over time; a new intermediate product, named as SCMC-CXP inserting in the montmorillonite interlayers is existed. With the isolating-standing time lasting, the amount of SCMC-CXP inserted into montmorillonite interlayers increases first and then decreases, and decreases with the increase of water-material ratio. A “sandwich” structure could be formed in the hydrogel, which is composed of the montmorillonite layers and the SCMC-CXP inserted into the montmorillonite interlayers. Further, in the whole SCMC-Bent based hydrogel system, a 3-dimentional net structure forms gradually that is composed of montmorillonite layers, SCMC-CXP inserted into montmorillonite interlayers and other SCMC-CXP outside the montmorillonite interlayers. ④ The 3-dimentional net structure formed is the reason causing the SCMC-Bent based hydrogel viscosity increasing consequently. However, due to the decrease of montmorillonite layer number and the breakage of SCMC-CXP molecules chain over time, the dispersion of the 3-dimentional net structure occurs, inducing the decrease of the viscosity. What’s more, high water-material ratios make the SCMC-CXP insertion amount decrease and weak the interaction of macromolecules, enhancing the water transportation capacity in the hydrogel, and inducing the viscosity becoming lower.