浅埋隧道围岩压力计算方法

提出一种基于位移反分析法原理的浅埋隧道围岩压力计算方法,该方法克服了传统计算方法依赖于经验围岩力学参数的不足。通过分析双侧壁导坑法中隧道的截面结构,提出合理假设并建立力学模型,然后建立新的侧壁、围岩的收敛变形与围岩压力之间的关系,由现场监测数据整理得到收敛变形反算求得水平围岩压力与垂直围岩压力,并以祥岭隧道为例,对该方法进行验证。研究结果表明:(1)基于位移反分析原理推导的围岩压力计算方法,利用现场监测数据反算求得围岩压力相较于规范依赖经验参数的计算方法,更准确、更能代表隧道的实际围岩压力;(2)在实际工程施工中,相较于围岩力学参数,隧道的收敛变形数据更易获得,计算更方便;(3)对祥岭隧道进行实例计算求得的围岩计算摩擦角以及最后求得的围岩压力都在规范推荐范围之内,说明本文的计算方法是可行的。该计算方法在隧道工程实践中,对于准确计算隧道开挖过程中的围岩压力以保证施工的安全、顺利完成有重要意义。

Calculation Method of Surrounding Rock Pressure in Shallow Tunnel

A new calculation method of surrounding rock pressure in shallow tunnel based on displacement backanalysis is proposed,the new method overcomes the shortcomings of the traditional calculation method that depends on empirical parameters of the surrounding rock.Making reasonable assumptions by analyzing the tunnel section structure of the double side heading method,a simplified mechanical tunnel model can be built and the relationship between bending moment and load was then deduced,through the conversion between bending moment and deformation,the relationship between load and deformation could be finally obtained.The deformation of the surrounding rock was obtained by collating monitoring data,and then the convergence deformation data could be substituted into the new method to calculate the surrounding rock pressure.The parameters were calculated at the same time and the calculation results of rock pressure were verified by comparing the parameters with specifications.The research shows:(1) The traditional method of calculating the surrounding rock pressure depends on the empirical parameters,but the new method uses the monitoring data to calculate the parameters and the surrounding rock pressure,so the rock pressure calculated with the new method is more accurate;the calculation method of surrounding rock pressure is derived based on displacement back analysis principle;(2) In the actual construction,the date of the convergence deformation of the tunnel can be obtained by finishing the monitoring data,which is more convenient and easier to obtain than the mechanical parameters in the traditional method,so the new method is of practical value;(3) The new method is verified by Xiangling tunnel.The friction angle and the rock pressure of surrounding rock calculated in new method by using the project information and the monitoring data are both within the specification,which indicates that the new method is feasible.The rock pressure or the deformation of surrounding rock can be calculated in the new method with only monitoring data which is easy to obtain.The parameters calculated with the new method can reflect the construction of the situation to a certain extent.The new method is more accurate and easier than traditional method and it is of great significance for completing the project safely and fast.