盾构切削大直径钢筋混凝土桩基新型刀具研究

Study on New-style Cutter for Shield Cutting Large-diameter Reinforced Concrete Pile

依托苏州地铁盾构连续切削14根Φ1 000~Φ1 200公路桥桩工程,通过理论分析、三维动态仿真和大型切桩现场试验等,对可直接切削大直径钢筋混凝土桩基的新型刀具展开研究。研究结果表明：切桩刀刃宜选用零后角和负前角,研发的新型贝壳刀可适应于连续切削多根大直径桩基,切削钢筋机理为剪切切削,切削混凝土机理为挤压损伤;新型贝壳刀切削钢筋形成V形切槽,刀身最大应力不超过1 500 MPa,合金刀刃最高温度291℃;新型贝壳刀单次切削混凝土范围为刀身所经过的横截面区域,切削效果呈跃进破碎特征,切向力与贯入力的比例关系约为5∶2;无论是切削钢筋或混凝土,硬质合金刀刃的磨损类型均为磨粒磨损,新型贝壳刀的磨损系数约为0.77mm·km-1。

Based on the construction of shield cutting of 14 highway bridge piles with the diameters ofΦ1 000~Φ1 200 continuously in Suzhou Subway,one new-style cutter for cutting large-diameter reinforced concrete piles directly was investigated by theoretical analysis,threedimensional dynamic simulation and large field test of cutting piles.The results show that the cutter blade with zero back angle and negative front angle should be chosen and the new-style shell cutter is fit for cutting many large-diameter piles continuously.The new-style cutter breaks rebar with the mechanism of shear cutting and breaks concrete with the mechanism of squeezing damage.The steel is cut to form V-type groove by new-style shell cutter,the maximum stress of the cutter body is less than 1 500 MPa and the maximum temperature of the alloy blade is 291℃.The cutting concrete range of the shell cutter is the cross sectional region which the cutter body passes through.The effect of cutting concrete shows the characteristics of the jumping break and the ratio of tangential force to penetration force is about five to two.Whether cutting rebar or cutting concrete,the wear type of cemented carbide blade is abrasive wear.The wear coefficient of new-style shell cutter is about 0.77mm·km-1.