【摘要】 采用理想弹塑性荷载传递函数,通过分析极限承载力与锚杆长度的关系,推导了锚杆临界锚固长度的解析算式,并在此基础上进一步分析了摩阻力分布、极限锚固力与锚固长度的关系。分析表明,当锚固长度小于工程临界锚固长度时,摩阻力分布较为均匀,而锚固长度的增加对极限承载力提高明显。基于这一点,建议锚杆的设计长度应小于工程临界锚固长度。为方便工程应用,还提出了工程临界锚固长度的理论计算方法和快速估算方法。更多还原

【Abstract】 Up to now,the analytical estimation of critical anchorage length,which is a very important parameter in bolts design,is not available. A perfectl elasto-plastic load-transfer model is used to derive an analytical solution for this problem. Based on the developed analytical solution,an analytical critical anchorage length (ACAL) formulation,which relates the anchorage diameter,anchorage deformation modulus,and anchorage layer characteristic coefficient with the critical anchorage length,is obtained. The analytical solution also shows a trend of more uniform distribution of the frictional resistance when the anchorage length is less than ACAL. The frictional resistance distribution becomes very uneven when the anchorage length is larger than half of the ACAL. Further study shows that the ultimate bearing capacity of the bolt increases significantly as the anchorage length increases within half of the ACAL,while the anchorage length is larger than half ACAL the effect of anchorage length on bearing capacity is limited. Based on the above findings,it can be seen that half ACAL is a very important parameter indicating the efficiency of the bolts. Thus,it is defined as“engineering critical anchorage length”and it is suggested that the designed anchorage lengths of bolts should be below their engineering critical anchorage lengths. Two convenient methods for practical use of estimation of the engineering anchorage length are presented with examples.更多还原