压力型锚索承载板前砂浆体破坏机制试验研究

压力型锚索承载板前砂浆体抗压承载力是影响压力型锚索整体有效性的重要因素之一。为了研究砂浆体的强度,设计了一个自适应多向应力加载装置,在单向试验机上按实际受力条件模拟了锚固砂浆体的受压破坏过程。带孔圆柱形砂浆体的配合比、尺寸和开孔基本按实际条件制作,根据相关理论和试验研究,确定了试件侧表面上正应力和剪应力的取值范围,以此为依据对受压试件施加侧向正应力和剪应力,得到了多组试件的抗压强度和应力应变关系,分析了试件的破坏形态。试验结果表明,砂浆体在侧向压力和表面剪应力共同作用下,其受力情况比单轴条件下更好,抗压强度有明显提高,提出了经验公式用于计算这种有利作用。公式的预测结果与现场试验结果进行了对比,提出了岩石强度与侧向压力对应关系的建议。

Failure mechanism of mortar in front of bearing plate of compression type anchor cables

The overall capacity of compression type anchor cables is influenced by the compression capacity of the mortar in front of bearing plate. For assessing the capacity of the mortar, the compression failure process of anchoring mortar under actual stresses is simulated by a self-adaptable multiaxial stress loading device on a uniaxial test machine. The mixture ratios, proportions and holes of cylindrical mortar specimens are made according to engineering conditions. The normal and tangential stresses decided by theoretical and experimental researches are exerted on the side face of the mortar. The compressive strengths, stress-strain curves and failure patterns of mortar specimens are obtained by the tests. The results show that the compressive strengths of the mortar are enhanced by the lateral normal and tangential stresses. By comparing laboratory experiment with field test results, empirical formulas for predicting the enhancement effect and the empirical relationship of rock compressive strength and lateral stresses are suggested.