摘要
隧道设计的荷载-结构法中,围岩抗力系数是影响衬砌内力与变形的重要参数,节理的存在会导致抗力系数的各向异性,然而,目前工程中较少考虑抗力系数的各向异性问题.以大连地铁2号线兴工街站隧道工程为背景,针对含有两组贯通节理岩体抗力系数的各向异性分布特征,采用正交试验和离散元数值模拟,分析岩石弹性模量、泊松比、节理间距、节理倾角、节理法向刚度等10个影响因素作用下抗力系数的分布规律.结果表明:洞周围岩抗力系数分布曲线呈椭圆形,长轴沿两组节理夹角角平分线方向;方差分析中5%水平下的显著性影响因素依次为节理法向刚度、岩石弹性模量、节理间距与节理倾角;各向异性系数随洞径与节理间距比值的增大呈现出先增大后减小的规律,当比值趋近于零或无穷大时,各向异性系数收敛于1.基于上述分析结果,进一步推导出围岩抗力系数椭圆分布函数的理论计算公式,并验证公式的准确性.工程实例计算表明,围岩抗力系数的各向异性对衬砌轴力的影响较小,对弯矩的影响显著.
In load-structure model for tunnel design,the rock mass resistant coefficient(k)is an important parameter which affects the behavior of the tunnel structure prominently.The anisotropy of k appears due to the presence of joints.However,no adequate efforts have been made to research the anisotropic distribution of k in jointed rock masses.Ten influencing factors including the elastic modulus of rock,Poisson’s ratio,and the properties of two sets of joints were analyzed for evaluating the anisotropic distribution of k,by using orthogonal array testing strategy(OATS)and distinct element method(DEM),with Xinggongjie Station Tunnel Project on No.2 Line of Dalian Metro as an example.The results show that the distribution curves of k were oval-shaped.The maximum value was along the direction of the two joints angle bisector.Using the variance analysis of OATS,the significant influencing factors at the level of five percent were the elastic modulus of the rock,the normal stiffness of the joints,the spacing of the joints,and the intersection angle of two sets of joints.With the increase of the ratio of tunnel diameter to joint spacing,the anisotropy coefficient of k increased first and then started to drop,which converged to one when the ratio was equal to zero or infinite.Based on the above analysis results,the elliptic function of k was derived and was verified.The engineering example shows that the resistant coefficient of jointed rock mass is obviously anisotropic,which has little influence on the axial force of lining and remarkable influence on bending moment.
作者
涂洪亮
乔春生
朱举
TU Hongliang;QIAO Chunsheng;ZHU Ju(School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China)
出处
《哈尔滨工业大学学报》
EI
CAS
CSCD
北大核心
2019年第2期90-99,共10页
Journal of Harbin Institute of Technology
基金
国家自然科学基金面上项目(51478031)
关键词
节理岩体
围岩抗力系数
各向异性
正交试验
方差分析
椭圆分布函数
jointed rock masses
rock mass resistant coefficient
anisotropy
orthogonal array testing strategy
variance analysis
elliptical distribution function
