软质岩中压力型锚索锚固段应力分布特征

Stress Distribution in Fixed Anchor Length of Compression Type Anchor in Soft Rock Mass

为了研究软质岩中压力型锚索锚固段应力分布和传递规律,进行了足尺现场试验。制作了与实际工程条件相似的试验锚索,在试验锚索的锚固段砂浆体中按一定间距设置了应变砖,记录了在不同张拉荷载下各测点的应变情况,测得压力型锚索锚固段的轴向应变和径向应变分布曲线。通过对试验结果进行分析处理,得到了锚固段与围岩界面剪应力分布曲线。测试结果与已有理论计算结果比较吻合。分析结果表明,在软质岩条件下,承载板附近的锚固体出现了明显的三向应力状态;锚固体中应力传递长度较短;注岩界面剪应力峰值可以达到较高的水平;随着荷载增大,剪应力有向前转移扩张的趋势。

To study stress distribution in fixed anchor length of compression type rock anchor cable, field test was carried out. Strain sensors were placed in the grout paste in fixed anchor length with certain interval. Axial and radial strains of the grout were noted by test. Shear stress distribution curve along the fixed anchor length was obtained by stress-strain relationship and static equilibrium analysis. Analysis results prove that maximal shear stress on the interface can achieve upper level and move forward when the load increases; the transmission length is short; shear stress transfers forward; and three dimensional state is obvious around capacity plates in soft rock mass.