深覆土梯形拱明洞静力特性及卸荷效果  

Static Characteristics and Unloading Effect of Deep Overburden Soil Ladder Arch Tunnel

作　　者：马莉[1] 禄云华 王起才[1] 马晓波[2] 李盛[1] 张克勋 MA Li;LU Yunhua;WANG Qicai;MA Xiaobo;LI Sheng;ZHANG Kexun(School of Civil Eng.,Lanzhou Jiaotong Univ.,Lanzhou 730070,China;China Railway First Survey and Design Inst.Group Co.,Ltd.,Xi’an 710043,China)

机构地区：[1]兰州交通大学土木工程学院,甘肃兰州730070 [2]中铁第一勘察设计院集团有限公司,陕西西安710043

出　　处：《工程科学与技术》2024年第4期120-129,共10页Advanced Engineering Sciences

基　　金：甘肃省基础研究创新群体项目(21JR7RA347);甘肃省自然科学基金项目(22JR5RA338);国家自然科学基金项目(51868041)。

摘　　要：为研究深覆土条件下梯形拱结构–填土相互作用对周围土压力的影响机制和卸荷机理,明确梯形拱明洞相较于传统矩形明洞的优势,采用室内模型试验和数值模拟相结合的方法,对深覆土梯形拱明洞静力特性及卸荷效果进行分析。结果表明:无减载时,梯形拱明洞两侧回填土沉降大于上方回填土沉降,两侧回填土土压力向明洞上方转移,土压力随着填土高度的增大而增大,基本呈线性变化趋势;减载时,明洞上方回填土沉降大于两侧回填土沉降,回填土内部产生土拱效应,明洞上方回填土土压力向两侧转移,铺设减载层不会改变深覆土明洞结构受力分布,但会极大地减小其内力及变形,并提高结构安全系数;减载后,梯形拱明洞的最大轴力、最大正弯矩和最大负弯矩分别减少17.5%、34.1%、29.9%,最大变形减小32.9%。矩形和梯形两种截面形式下明洞的最大轴力均出现在中隔墙底部,最大正弯矩、最小安全系数和最大变形均出现在顶板中央位置;铺设减载层后两种截面形式拱明洞最小安全系数分别增大42.6%和100.0%,梯形拱明洞安全系数提高的比例更大,效果更显著。该研究可为深覆土梯形拱明洞结构的设计和施工提供理论指导和技术支持。Objective This study analyzes the static characteristics of trapezoidal arch openings and the unloading effect in deep overburden conditions to investigate the influence of the trapezoidal arch structure-fill interaction on surrounding soil pressure and unloading mechanisms.Additionally,it aims to clarify the advantages of trapezoidal arches over traditional rectangular arches.Methods This analysis combines indoor modeling tests and numerical simulations.In the experimental phase,organic glass plates serve as the test material.A numerical model and the specific thickness of the test material are deduced.Additionally,the preparation of a rubber granular soil mixture and its related compression and shear characteristic tests are conducted.In the numerical simulation phase,following verification with the indoor model test,the finite difference software FLAC3D and the discrete element software PFC2D are employed to establish the subway station model.Discrete elements primarily describe the fine contact between backfill particles,facilitating a better observation of the distribution of the contact force chain of the backfill around the openings.The static analysis of the deep overburden trapezoidal arch openings and their load unloading is also evaluated.Results and Discussions The study attributes the observed decrease in soil pressure to the gradual reduction of load shedding.The load reduction material enhanced the soil settlement at the top of the arch,creating a settlement difference within the soil column and forming a soil arch effect.This effect caused the soil pressure at the top of the arch to transfer to the sides,with the cross-section type exerting minimal influence on the settlement and distribution of the backfill above the opening.Before load reduction,the maximum axial force,the maximum positive bending moment,the minimum safety coefficient,and the maximum deformation of the lining in the trapezoidal arch roof slab opening all occurred at the central position of the roof slab.The maximum negative bend

关 键 词：深覆土 梯形拱明洞 静力特性 卸荷效果 

分 类 号：U451.4[建筑科学—桥梁与隧道工程]