摘要
60 m级跨度的扁平地下洞室围岩压力计算,超出了已有计算方法的适用范围。文章对比分析了采用已有的公式计算超大跨扁平地下洞室围岩压力荷载值及其影响因素,最终以普氏公式为基础,结合过程荷载的理念及施工方法,把超大跨的横断面离散成若干小跨洞室,最后得出考虑施工过程的超大跨扁平地下洞室围岩压力荷载值。用有限差分软件进行三维数值模拟,得到了拱顶沉降随开挖面推进的关系、地表沉降范围及其最大值随开挖面推进的变化关系。以0.00025的竖向应变作为临界应变得出洞室顶部围岩的松动范围,即求得松动围岩压力荷载值。对比分析三种方法(一次开挖,过程荷载,数值计算)的计算结果可知,直接将已有的经验公式应用于文章的研究对象得出的围岩压力值大于过程荷载值和数值计算结果,而数值计算结果和过程荷载值相近。因此,把过程荷载用于超大跨扁平地下洞室围岩压力计算具有一定的实际工程意义。
The computation of surrounding rock pressure of 60 m span flat underground cavern is beyond the scope of the existing calculating methods.The empirical formulas and influencing factors are compared and ana⁃lyzed.Based on Protodyakonov formula,the concept of process load and construction method,the cross section of cavern with super large span is divided into several small span caverns,and the surrounding rock pressure of super large span flat underground caverns is obtained considering the construction process.The relationship between the settlement of crown and the distance from the excavation face,the range and its maximum value of ground surface set⁃tlement caused by the advance of excavation are obtained by three-dimensional numerical simulation using finite dif⁃ference method.Taking theεz of 0.00025 as the critical strain,the loose scope and pressure load of surrounding rock are obtained.By comparing the calculation results of the three methods(one-cycle construction,process load and nu⁃merical calculation)it can be seen that the pressure value of surrounding rock obtained by applying the existing em⁃pirical formula directly is larger than the process load value and the numerical calculation result,while the numeri⁃cal calculation result is similar to the process load value.Therefore,the process load has certain reference signifi⁃cance for the calculation of the surrounding rock pressure of the super large span flat underground cavern.
作者
孙玉龙
闫治国
SUN Yulong;YAN Zhiguo(Department of Geotechnical Engineering,Tongji University,Shanghai 200092)
出处
《现代隧道技术》
EI
CSCD
北大核心
2020年第5期91-98,共8页
Modern Tunnelling Technology
关键词
超大跨
扁平洞室
围岩压力
过程荷载
数值模拟
塌落区
Super-large span
Flat cavern
Surrounding rock pressure
Process load
Numerical simulation
Col⁃lapse area
