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地质力学模型试验均布压力精确加载是保证试验精度的前提。为此研制了一种新型柔性均布压力加载系统,该系统主要包括液压自动控制系统和柔性均布压力加载装置。液压自动控制系统操作方便,可实现计算机自动控制12路压力精确伺服加、卸载和长期稳压。柔性均布压力加载装置由液压油缸、球铰、刚性推力器和柔性传力橡胶垫块等组成,采用数值方法确定柔性橡胶的厚度为50 mm。该系统应用到表面不平的模型加载中并与刚性加载进行了对比。试验结果表明,柔性均布压力加载系统相对于刚性加载效果显著,模型内应力场均匀程度取决于橡胶传力垫块的邵氏硬度、加载应力大小和距表面深度。邵氏硬度小的橡胶柔性加载模型内应力场更均匀;且模型应力场随加载应力增大趋于均匀。模型内应力场距加载表面越远越均匀,柔性加载使距加载表面130 mm以下应力场基本保持均匀状态。试验表明,柔性均布压力加载系统有利于提高模型试验加载精度,具有广泛的应用前景。
Geomechanical model test uniform pressure load is accurate to ensure the accuracy of the premise. For this reason, a new type of flexible uniform pressure loading system has been developed. The system mainly consists of hydraulic automatic control system and flexible uniform pressure loading device. Hydraulic automatic control system easy to operate, enabling automatic control of the computer 12-channel pressure precision servo plus, unload and long-term regulator. The flexible uniform pressure loading device consists of a hydraulic cylinder, a ball joint, a rigid thruster and a flexible force transmission rubber pad. The thickness of the flexible rubber is determined to be 50 mm by numerical methods. The system is applied to uneven surface loading and compared with rigid loading. The experimental results show that the flexural uniform pressure loading system has a remarkable effect compared with the rigid loading. The uniformity of the stress field in the model depends on the Shore hardness, load stress and surface depth of the rubber transfer pad. The stress field of the rubber flexible loading model with small Shore hardness is more uniform; and the stress field of the model tends to be uniform with the increase of the loading stress. The stress field in the model farther and farther away from the loading surface, and the stress field under 130 mm from the loading surface remained almost uniform due to the flexible loading. Experiments show that the flexible uniform pressure loading system is beneficial to improve the loading accuracy of model test and has a wide range of application prospects.