Reasonable Support Timing of Tunnel Pre-grooving Method and Research on Segment Joint Structure
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摘要: 预切槽法是隧道暗挖施工的一种超前支护工法，此工法可大幅度降低地表沉降量，对隧道围岩土体及地表建（构）筑物影响较小。采用室内试验和数值模拟的方法，针对浇筑预切槽管片所用混凝土的前期强度、合理支护时机以及预切槽管片接头处合理的接茬方式进行了研究。研究结果表明，按C30配比的混凝土养护1.5～2 h时即具有6 MPa以上的抗压强度，满足拆模要求；粘接介质对管片环向位移的约束效果明显，环氧树脂可作为优良的管片粘接剂；榫槽式接头榫头角度α的理想范围为55° ～ 70° ，综合考虑预切槽工艺的可操作性，榫槽式接头深度B的理想范围为6～8 cm。Abstract: Pre-grooving method is a kind of over-advance support method for tunnel excavation, which can greatly reduce the amount of surface settlement, and has less impact on the tunnel surrounding rock and soil and surface buildings (structures). Using indoor tests and numerical simulation methods, the research was carried out on the strength of the concrete used for casting pre-grooving duct piece, the reasonable support timing, and the reasonable stubbing method at the joints of the pre-grooving duct piece. The results show that the concrete with C30 proportion has a compressive strength of more than 6 MPa when curing for 1.5~2 h, which meets the requirement of mold removal; the bonding medium has obvious restraining effect on the circumferential displacement of the duct piece, and epoxy resin can be used as an excellent bonding agent for the duct piece; the ideal range of mortise and tenon joint mortise angle α is 55°~70°, and the ideal range of the depth of the mortise and tenon joint is 6~8 cm, taking into consideration of the operability of the pre-grooving process.
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表 1 硅酸盐水泥的性能指标
比表面积/
（m2·kg−1）堆积密度/
（kg·m−3）凝结时间/
min抗压强度/
MPa抗折强度/
MPa357 1200 初凝 终凝 3 d 28 d 3 d 28 d 195 267 26.5 42.5 5.5 6.5 
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表 2 接头设计分组表
深度
B/mm 夹角α 40° 55° 70° 20 J1 J4 J8 40 J2 J5 J9 60 J3 J6 J10 80 J7 J11 注：其中α=40°、B=80 mm组合无法组成既定的榫槽式几何型式，故剔除该组合。
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表 3 数值模拟工况设计表
围压
/kPa粘接剂 无任何粘接剂 环氧树脂 水泥基胶 100 J1—J11 J1—J11 J1—J11 200 J1—J11 J1—J11 J1—J11 300 J1—J11 J1—J11 J1—J11 400 J1—J11 J1—J11 J1—J11 500 J1—J11 J1—J11 J1—J11
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表 4 数值模拟材料属性
材料 材料
类型单元
类型弹性
模量/
GPa泊松
比重度/
（kN·m−3）切向
弹性模量
/GPa混凝土 弹性/塑性 3D实体 17.8 0.2 23.5 钢筋 弹性 1D植入式
梁单元200 0.28 78 环氧树脂 界面 界面 4.08 0.32 20 1.54 水泥基胶 界面 界面 2.0 0.21 30 0.83
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表 5 榫槽式J1与平接头P1模拟结果表
接头型号 围压/kPa 环向位移/mm 环氧树脂 水泥基胶 J1 100 0.422 0.646 200 0.844 1.292 300 1.266 1.938 400 1.688 2.583 500 2.110 3.229 P1 100 0.425 0.654 200 0.850 1.308 300 1.274 1.964 400 1.698 2.681 500 2.123 3.272
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