压力型抗浮锚杆承载性能现场试验研究

Field Experimental Study on the Load-Carrying Performance of Pressure-Type Anti-floating Anchors

摘要:

为深入研究压力型预应力混凝土用螺纹钢筋(PSB)抗浮锚杆的承载性能和位移规律,以青岛某实际抗浮工程为例,针对3根压力型PSB抗浮锚杆开展现场试验研究。通过实时监测锚筋与灌浆体的位移变化,系统分析了荷载-位移演化规律,揭示了PSB抗浮锚杆的黏结应力分布特性。试验结果表明,锚筋与灌浆体位移随荷载增长呈线性增加趋势,受荷载水平影响显著;当荷载达到最大荷载的60%时,位移曲线出现骤升,进入加速增长阶段;灌浆体位移曲线整体呈线性增长,未出现突变点或双折线特征,锚筋与灌浆体的相对位移随着荷载增加而增大。该试验条件下,压力型PSB抗浮锚杆锚筋-灌浆体界面展现出的平均黏结应力为0.73 MPa,而灌浆体-岩土体界面的平均黏结应力则相对较低,为0.104 MPa。灌浆体-岩土体界面黏结应力与锚固长度和锚孔直径有关,锚固长度和锚孔直径过大反而会降低锚筋-灌浆体界面的黏结应力。

Abstract:

In order to deeply study the bearing performance and displacement law of pressure-type screw-thread steel bars for the prestressing of concrete (PSB) anti-floating anchors, this study took an actual anti-floating project in Qingdao as the background, and carried out field experimental study on three pressure-type PSB anti-floating anchors. The load-displacement evolution law was systematically analyzed by monitoring the displacement changes of anchor bars and grout body in real time, and the bond stress distribution characteristics of PSB anti-floating anchors were revealed. The test results show that the displacement of the anchor bar and grout body increases linearly with the load growth, which is significantly affected by the load level; when the load reaches 60% of the maximum load, the displacement curve rises abruptly and enters an accelerated growth stage; the overall growth of the grout body-displacement curve is linear, with no abrupt change point or bilinear characteristics. The relative displacement between anchor bars and grout body increases with the increase of load. Under the experimental conditions, the average bond stress of the pressure-type PSB anti-floating anchor bar-grout body interface is 0.73 MPa, while the average bond stress of the grout body-rock and soil mass interface is relatively low, which is 0.104 MPa. The bond stress at the interface between the grout body and the rock and soil mass is related to the anchoring length and the anchor hole diameter, and the excessive anchoring length and the anchor hole diameter will reduce the bond stress at the interface between the anchor bar and the grout body.