摘要
通过室内试验和ANSYS有限元模拟,研究了沟槽式高填黄土明洞结构受力特性,得到了明洞减载前后周围土压力、位移及外侧应力随填土高度的变化规律。在此基础上,探讨了EPS板密度、厚度、宽度、铺设位置及填土高度等参数对EPS板减载明洞结构内力的影响。结果表明:数值模拟与模型试验表现出一致的规律,即采取EPS板减载后,拱顶、拱底和拱肩土压力减小,拱腰和侧墙土压力增加;明洞侧墙向外变形、拱顶向内变形减小;明洞外侧应力均减小。10 kg/m^3密度的EPS板Mises应变已到硬化阶段,后期已无减载能力,而20 kg/m^3、30 kg/m^3的EPS板应变处于塑性阶段,后期仍有减载空间。EPS板厚度越大,内力减载量越大,减载效果越明显,但厚度大的EPS板Mises应变小,材料未能充分利用;随着EPS板宽度增加,明洞结构内力先增大后减小;当EPS板宽度为1～1.5倍洞宽时,明洞内力减载量达到最优状态;EPS板距明洞顶距离越小,EPS板Mises应变越大,使得明洞衬砌结构内力减载量越大。建议EPS板铺设在洞顶0～1 m范围内。随着填土高度的增加,明洞衬砌结构内力减载量逐渐增大,而其变化率逐渐减小。
Through the relevant laboratory experiment and ANSYS finite element simulation, the mechanical characteristics of the trench-type high fill loess open-cut tunnel is studied herein, and then the changing laws of the surrounding earth pressure, displacement and the outside stress of the open-cut tunnel before and after load-reduction are obtained. On the basis of this, the influences from the parameters of the density, thickness and width of EPS plate and its placing position as well as the height of fill on the structural internal force of the open-cut tunnel with load-reduction of EPS plate are discussed. The result shows that both the numerical simulation and the model experiment exhibit the law of uniformity, that is to say, the earth pressure decreases at the vault, arch bottom and spandrel and increases at the haunch and side walls, while the outward deformation of the side wall of the open-cut tunnel and the inward deformation of the vault decrease along with the decreases of all the outside stresses of the open tunnel. The mises strain of EPS plate with the density of 10 kg/m^3 reaches the hardening phase and has no load-reduction capacity in the later period, while the strains of the EPS plates with the densities of 20 kg/m^3 and 30 kg/m^3 are still at their plastic phases and have the allowances for load-reduction in the later period. The larger the thickness of EPS plate is, the larger load-reduction of the internal force is to be and more obvious effect of load-reduction is to be as well. However, if the mises strain of the EPS plate with large thickness is small, the material cannot be fully utilized. Along with the increase of the thickness of EPS plate, the structural internal force of the open-cut tunnel increases at first and then decreases. When the width of EPS plate is 1~1.5 times of the tunnel width, the load-reduction of the internal force of the open-cut tunnel reaches the optimum state. The less the distance of EPS plated to the top of the open-cut tunnel is, the larger the mises strain of E
作者
刘亚朋
李盛
宁贵霞
卓彬
于本田
LIU Yapeng;LI Sheng;NING Guixia;ZHUO Bin;YU Bentian(School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou730070, Gansu, China)
出处
《水利水电技术》
北大核心
2019年第4期153-161,共9页
Water Resources and Hydropower Engineering
基金
国家自然科学基金项目(51668036)
甘肃省高等学校科学研究一般项目(2017A-111)
长江学者和创新团队发展计划项目(IRT_15R29)
甘肃省高校协同创新科技团队支持计划项目(2017C-08)
兰州交通大学优秀科研团队项目(201606)
关键词
高填黄土明洞
减载
EPS板
受力特性
影响因素
high fill loess open-cut tunnel
load-reduction
EPS plate
mechanical characteristics
