深部高应力、软弱围岩、强烈采动影响等条件下的巷道围岩频繁出现大变形，此类围岩大变形支护可控性普遍较差，常规锚索因其较低的延伸率无法适应巷道大变形而大量破断或锚固失效，导致巷道出现冒顶隐患。针对此类问题，研发了一种与常规锚索配合使用的复合扩管式恒阻器，其结构主要由止进端盖、扩径管、一体式托盘和锥式锁具组成，通过锥式锁具克服扩径管“扩胀—摩削”所产生的近似恒定的复合阻力，实现围岩大变形过程中的锚索支护阻力恒定，通过理论分析、数值模拟和静力拉伸试验等综合研究方法，系统分析和试验了复合扩管式恒阻器的力学特性和工作稳定性，掌握了该恒阻器扩径增量、锁具锥角对扩径管变形及恒阻器复合阻力的影响规律。试验结果表明：恒阻器复合阻力主要分为阻力快升段和近恒定阻力段2个过程，且近恒定阻力段作为主要阶段达到试验全程的85%～90%；锁具锥角、扩径增量直接影响了扩径管变形及恒阻器力学特性，锁具锥角小于20°时，扩径管变形均匀且恒阻器复合阻力发挥稳定，而扩径增量则决定了恒阻器复合阻力的大小，可通过调整扩径增量获取需要的锚索恒阻力；$phi $17.8 mm锚索条件下，当锁具锥角为15°、扩径增量为5 mm时，恒阻器恒定阻力约为265.92 kN，$phi $21.8 mm锚索条件下，当锁具锥角为15°，扩径增量为8 mm时，恒阻器恒定阻力约为424.15 kN，且工作状态稳定可靠，可较好的符合大变形巷道的恒阻支护要求。此外，该恒阻器还具有工作稳定性强、恒阻行程及阻力可调、结构简单、安装便捷等特点，是大变形巷道围岩控制技术的有效补充。

Under the conditions of deep high stress, weak surrounding rock, and strong mining influence, the surrounding rock of deep-buried roadway frequently experiences large deformations, the controllability of large deformation support for this type of surrounding rock is generally poor, and the conventional anchor bolts often break or fail to anchor due to their low elongation rate, which cannot adapt to the large deformation of the roadway, resulting in the risk of roof caving in the roadway. The constant resistance device by using composite expansion pipe (CRD-cep) used in conjunction with cable bolt has been invented. The main structures include a stop end cover, an expansion pipe, an integrated tray and a conical lock. The conical lock overcomes the approximately constant composite resistance generated by the “expansion grinding” of the expanding pipe, thus, the constant resistance of the cable bolt during the large deformation process of the surrounding rock is achieved. The mechanical characteristics and working stability of the resistance stabilizer are improved by theoretical analysis, numerical simulation and static tensile testing and other comprehensive research methods, and the influence of the expansion increment and lock cone angle of the composite expansion tube constant resistance device on the deformation of the expansion pipe and the composite resistance of the CRD-cep has been understood. The test results indicate that the composite resistance of the CRD-cep is mainly divided into two processes: the fast rising resistance stage and the near constant resistance stage, and the nearly constant resistance section as the main stage reaches 85% to 90% of the entire test process. The lock cone angle and expansion increment directly affect the deformation of the expansion pipe and the mechanical characteristics of the CRD-cep. When the lock cone angle is less than 20°, the deformation of the expanding pipe is uniform and the composite resistance of the CRD-cep is stable. The expanding increment determines the size of the CRD-cep. The required constant resistance of the cable bolt can be obtained by adjusting the expanding increment. When the diameter of the anchor rope used is 17.8 mm, the lock cone angle is 15° and the expansion increment is 5 mm, the constant resistance of the CRD-cep is about 265.92 kN, when the diameter of the anchor rope used is 21.8 mm, the lock cone angle is 15° and the expansion increment is 8 mm, the constant resistance of the CRD-cep is about 424.15 kN, and the working state is stable and reliable, which can better meet the constant resistance support requirements of large deformation roadway. The CRD-cep has the characteristics of strong working stability, adjustable constant resistance stroke and resistance, simple structure, and convenient installation, which is an effective supplement to the control technology of surrounding rock in large deformation roadway.