摘要
土压平衡盾构掘进时土舱压力的设定往往缺乏足够的理论支撑,其内部掘削土体颗粒的运动规律也无法直观展现。基于离散单元法(DEM)对土舱内砂卵石颗粒集合进行三维精细化仿真,通过支持向量机反演标定细观接触参数,获得了土舱内部颗粒流速度场分布情况和运移沉积规律,纵向上从土舱前端到隔板流动效果越来越差,横断面上靠近辐条外边缘及支撑柱附近区域的流动性较好,结合局部滞流特征提出了土舱内部结构优化措施。进一步阐述土颗粒内部接触力链变化更迭特征,分析了土舱隔板压力分布情况,其总体上呈现隔板压力左右对称,从上而下逐渐增大的特征。同时揭示了在砂卵石地层中开口率为66%的辐条式刀盘盾构机土舱隔板压力与刀盘前支护压力的映射关系,DEM计算所得压力传递系数为0.7711,土舱隔板压力的合理设定值为47.08 kPa~70.69 k Pa,研究成果可为砂卵石地层盾构土舱压力的设定提供理论基础。
Parameters setting of earth chamber pressure in earth pressure balanced(EPB)shield tunneling lacks adequate theoretical guidance.Particles motion law among excavation soil in earth chamber also cannot be visualized intuitively.Sandy pebble multi-particle aggregate with 3 D fine model of earth chamber system is simulated using discrete element method(DEM).Some mesoscopic contact parameters of sandy pebble soil can be calibrated through inverse analysis with support vector machine,and the velocity distribution and motion law of soil particles in chamber can be obtained.The flowability declines longitudinally from the front of chamber to the clapboard,and the flowability near the outer edge of spokes and pillars is better on the cross-section of the earth chamber.Combined the stagnation characteristics of local flow,an optimization measure for the internal structure of the earth chamber is proposed.Furthermore,the changing feature of the contact force chain in soil particles is elaborated,and the pressure distribution on chamber clapboard is analyzed.Generally,it is symmetric and increases from top to bottom.In addition,the mapping relationship between clapboard pressure and supporting pressure is revealed with an opening ratio of 66%in sandy pebble.The pressure transmission coefficient calculated by DEM is 0.7711,and the reasonable pressure range on the chamber clapboard is 47.08~70.69 k Pa.The research results can provide a theoretical basis for controlling the pressure of shield tunneling in sandy pebble stratum.
作者
李培楠
翟一欣
程盼盼
朱合华
Li Penan;Zhai Yixin;Cheng Panpan;Zhu Hehua(College of Environmental Science and Engineering,Donghua University,Shanghai 201620,P.R.China;Shanghai Tunnel Engineering Co.Ltd.,Shanghai 200232,P.R.China;College of Civil Engineering,Tongji University,Shanghai 200092,P.R.China)
出处
《地下空间与工程学报》
CSCD
北大核心
2021年第5期1517-1528,共12页
Chinese Journal of Underground Space and Engineering
基金
上海市青年科技启明星计划(18QB1403800)
上海市优秀技术带头人计划(15XD1523000)。
关键词
土压平衡盾构
砂卵石土
颗粒运动规律
土舱传力特性
离散单元法
EPB shield
sandy pebble soil
particles motion law
force transmission characteristics in earth chamber
DEM method
