杆状支护系统的耦合模型及应用

COUPLING MODEL OF BOLT REINFORCEMENT SYSTEM AND APPLICATION

锚杆/锚索等杆状支护系统在土木工程界的应用很广。但到目前为止,杆状支护物与被支护体之间的耦合机理却尚未十分清晰,有关支护效果的可靠合理的评价方法也并未成熟。基于Shear-Lap理论,提出一种改良的计算分析方法来描述杆状支护材料、交界面和被支护体之间的耦合作用机理。分析锚杆拉拔试验中由耦合到破坏的整个过程,提出一个计算交界面真实粘结强度的新方法。普通拉拔试验中,交界面的平均剪切强度低于其真实强度。二者的差别受支护杆的锚固长度和试件材料的物理力学性质的影响。若忽略试件材料的变形模量,可能导致试验的计算值与真实强度之间出现很大的偏差。分析不同变形模量试件体的拉拔试验过程,对于软岩支护中金属体的室内拉拔试验,建议试件材料的变形模量和相应的锚固长度。圆形隧道周边锚杆的受力状态分析表明,锚杆受力后存在拉拔区、中性点和锚固区。中性点的位置不但和隧道的几何尺寸有关,还与岩石的物理力学性质有关。计算结果和实测结果进行了对比,二者较为接近。

A normal analytical model for reinforcement is proposed, on the basis of refined Shear-Lag model, to describe the mechanical coupling at the interface between reinforcement and rock/soil mass. Coupling and decoupling behavior of reinforcement in pullout test is analyzed, and a new method is suggested to evaluate actual shear strength of interface between reinforcement and rock/soil mass. Average shear force is smaller than actual shear strength. The difference is related not only to the embed length of reinforcement, but also to the deformation modulus of matrix material. Interaction influence of anchor length and matrix's deformation modulus is often ignored in normal pullout test, which may leads to large deviation. Rational anchor length is suggested for pullout test. Analysis of bolt around tunnel shows that there is a pullout area, neutral point and anchor area along bolt. The position of neutral point is not only determined by geometry of tunnel, but also influenced by the rock mass properties. Theoretical prediction coincides well with testing data.