花岗岩残积土层压力型锚杆工程特性及机理研究

    Study on engineering characteristic and mechanism of compression type ground anchor in granite residual soil

    • 摘要: 在花岗岩残积土层中按实际工程作法施工了28根压力型试验锚杆,荷载试验及对浆体的分布式光纤测试结果表明:①锚筋从锚固体顶端向底端传递荷载过程中因孔道阻力而产生荷载损失;②视临界锚固长度约为12m,12m以内极限承载力与锚固体长度成正比,超过12m后增长缓慢;③浆体应变可分为前、中、后三段,后段受到承载板压力作用产生压应变,中段同时受到孔道阻力作用而以拉应变为主,前段受溢浆影响拉应变突增,中后段应变差表征了浆地界面粘结强度特性;④和全粘结锚杆相比,同等条件下压力型锚杆承载力低、变异程度大,压应变分布范围小、峰值低;⑤弹性变形实测比与荷载正相关,与锚筋自由长度负相关;⑥实测刚度系数与荷载水平及锚筋自由段长度负相关;⑦弹塑比大致与锚筋自由段长度负相关。

       

      Abstract: In the granite residual soil, 28 compression type ground anchor were made according to the engineering methods, the load tests of anchor and distributed fiber tests of grout were carried out. The results show that: (1) In the process of transferring load from the top of grout body to the bottom, the load loss occurs due to the tunnel resistance.(2) The apparent critical anchoring length is about 12m, the ultimate bearing capacity is proportional to the grout length within 12m, and after 12m it increases slowly.(3) The grout strain can be divided into front, middle and back sections. The back section is subjected to the pressure of the bearing plate and produces the compressive strain; the middle section is subjected to the tunnel resistance and the tensile strain is the main strain; the front section is affected by the overflow grout and produces the sudden increase of the tensile strain.The strain difference of middle and back section characterizes the bond stress.(4) Compared with the fully bonded anchor, the bearing capacity of the compression type anchor under the same conditions is lower, the variation degree is larger, the compressive strain distribution range is smaller, and the peak value is lower.(5) The measured ratio of elastic deformation is positively correlated with the load and negatively correlated with the tendon free length.(6) The measured stiffness coefficient is greater than the theoretical value, which is negatively correlated with the load level and roughly tendon tree length.(7)Elastic-plastic ratio is negatively correlated with the tendon free length.

       

    /

    返回文章
    返回