摘要
利用离散元软件PFC2D,考虑到土体的离散性与不均匀性,通过分析洞顶平均竖向土压力、内外土柱相对沉降差以及颗粒间接触力链的变化规律,探讨截面型式(矩形、1/4拱形、1/2拱形)及槽宽比(B/b=1.5∶1,2∶1,3∶1,4∶1)变化对高填黄土明洞土压力的影响,结合顾安全公式,分析高填明洞沉降差与土压力间的函数关系,并修正该函数,使其可以适用与不同的截面型式与槽宽比下的高填明洞。结果表明:(1)B/b确定,明洞采用矩形截面时,接触力链在洞顶分布,平均土压力更大,明洞采用拱形截面时,平均土压力更小,但拱顶存在局部应力集中现象;(2)明洞截面型式一定,随着B/b的增大,洞顶平均竖向土压力与沉降差均随之增大,当B/b较小时,边坡作用增强,外侧土柱沉降降低,对内土柱的作用力变小,从而导致明洞顶竖向土压力更小;(3)内外土柱沉降差与附加土压力呈线性相关,相对于矩形截面,拱形截面下较小的沉降差会产生相同的附加土压力,更有利于结构的稳定。
To explore the influences of section types(rectangular,1/4 arch,1/2 arch)and the groove-width ratio(B/b=1.5∶1,2∶1,3∶1,4∶1)on the earth pressure of the hill-filled cut-and-cover tunnel(HFCCT),this paper used the discrete element software PFC2D to simulate and analyze the evolution laws of the average vertical earth pressure(VEP)on the top of the cut-and-cover tunnel(CCT),the settlement difference between inner and outer soil columns,and the contact force chains among particles.Moreover,the paper analyzed the correlation between the settlement difference and the earth pressure based on the earth pressure theory of culvert and pipe,which was put forward by Gu Anquan,and further modified the function of the above-mentioned theory so as to make it applicable to the different section types and groove-width ratio(B/b).The results show that①when the B/b is determined,the contact force chains will distribute on the top of the CCT and the average vertical earth pressure(VEP)is greater if the CCT adopts a rectangular section.The average VEP will decrease if the CCT adopts an arched section.However,there is partly stress concentration at the top of the arched section.②When the section is determined,the average VEP and settlement difference on the top of CCT both increase with the increase of B/b.As the B/b decreases,the slope effect is enhanced,the settlement of the outer soil column reduces gradually,and the interaction between the inner and outer soil columns declines,which makes the VEP on the top of the CCT decrease.③The settlement difference between the inner and outer soil columns is linearly related to the additional earth pressure.Compared with the rectangular section,the same additional earth pressure under the arched section is generated by a smaller differential settlement,which benefits the stability of the structure.
作者
何永泽
李盛
后浩斌
马莉
贡力
余云燕
HE Yongze;LI Sheng;HOU Haobin;MA Li;GONG Li;YU Yunyan(College of Civil Engineering,Lanzhou Jiaotong University,730070 Lanzhou,China;Gansu Provincial Transportation Research Institute Group Co.,Ltd.,730030 Lanzhou,China)
出处
《应用力学学报》
CAS
CSCD
北大核心
2024年第2期330-339,共10页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金资助项目(No.51868041,51668036)
甘肃省基础研究创新群体资助项目(No.21JR7RA347)。
关键词
高填明洞
截面型式
槽宽比(B/b)
PFC2D
土压力
沉降差
hill-filled cut-and-cover tunnel(HFCCT)
cross-sectional shape
groove-width ratio(B/b)
PFC2D
vertical earth pressure
differential settlement
