压力分散型锚索锚固机制模型试验研究

MODEL TEST STUDY OF ANCHORING AND REINFORCING MECHANISM OF PRESSURE DIFFUSION ANCHOR CABLE

采用新的试验装置和试验方法对锚索单元实施分级循环加载,通过地质力学模型试验研究压力分散型锚索的锚固机制。试验结果表明:2单元压力分散型锚索采用分级循环加载后,受承载体间距L等因素的影响,第1单元注浆体的应变和轴力随长度的衰减较第2单元快,加载后锚索各单元的应变分布、黏结应力均值呈现"前小后大"的分布模式;与前次加载相比,对3单元压力分散型锚索的第2,3级承载体加载到0.6 kN后,第1单元的应变和轴力峰值出现了不同程度的下降,加载单元及待加载单元的黏结应力均值均有所提高;对4单元压力分散型锚索采用分级循环加载后,加载单元及待加载单元的应变和轴力峰值、黏结应力均值有所提高,而已加载单元注浆体的应变和轴力峰值有所降低;在锚固长度一定的条件下,承载体的数量对荷载有效传递有相当大的影响,特别是黏结应力的转移方式不同。上述试验成果对正确分析压力分散型锚索加固作用机制和锚固工程设计具有较好的参考价值。

A new test device and a new test method are adopted to implement grading cyclic loading onto each anchor unit and study the anchoring and reinforcing mechanism of pressure diffusion anchor cable by geological mechanics model test. The test results show that： as far as the pressure diffusion anchor cable with two anchor units is concerned, the strain and axial force of the grouting body of the first unit are influenced by the distance between the bearings and attenuates faster than that of another unit, the mode of the strain distribution and the average bond stress distribution of the units are smaller in the front unit and bigger in the back unit after loading. For the pressure diffusion anchor cable with three anchor units, compared with the previous loading, the peak strain and axial force of the first unit fall with different levels after loading 0.6 kN onto the 2nd and 3rd units~ and the average bond stresses of the loaded unit and unloaded unit are improved. For the pressure diffusion anchor cable with four anchor units, the peak strain and axial force and average bond stress of loading unit or unloaded unit have been improved, while the peak strain axial force and average bond stress of the loaded units reduce after grading cyclic loading. Under conditions of certain anchor length, the number of the bearing body has a considerable influence on the effective transfer of loads, especially the bond stress transfers in different ways. The experimental results have a good reference value for the correct analysis of anchoring and reinforcing mechanism and engineering design of the pressure diffusion anchor cable.