前言过去,结构物的设计使用许容应力法,设计中,首先要作应力分析。若所求得的应力小于材料的许容应力,则结构安全;若超过了,必须设法使计算应力小于许容应力。但对隧道一类的地下结构物,这种应力分析是不容易的。因为地下结构物上相当于荷载的围岩初始应力不明确,而且即使能测定,经济而精度高的求荷载的方法现在还未研究出来。一方面,构成围岩的材料的力学特性非常复杂,现场评定非常困难。即使是在最简单的弹性地基情况 Foreword In the past, the design of the structure used the Xu Rong stress method. In the design, stress analysis was first performed. If the calculated stress is less than the allowable stress of the material, the structure is safe; if it exceeds, the calculated stress must be less than the allowable stress. However, this type of stress analysis is not easy for underground structures such as tunnels. Because the initial stress of the surrounding rock equivalent to the load on the underground structure is not clear, and even if it can be measured, the economical and highly accurate method of obtaining the load has not been studied yet. On the one hand, the mechanical properties of the materials that make up the surrounding rock are very complex and field assessment is very difficult. Even in the simplest case of elastic foundations