无粘结环锚预应力衬砌张拉工艺足尺模型试验研究

Full-scale Model Test on Tensioning Technology of PrestressedLining with Unbonded Circular Anchor

针对预应力衬砌张拉过程中易出现应力集中而导致张拉裂缝的现象,通过开展洞外地面足尺模型试验,提出了分级分步张拉顺序和质量控制指标。首先根据钢绞线摩阻测试计算出摩擦系数,随后应用上述张拉顺序和质量控制方法进行自动张拉,并采用磁通量传感器和混凝土应变计分别对钢绞线和内衬混凝土的应力变化开展实测。现场张拉试验结果表明:①钢绞线沿程预应力损失约16.3%,采用的双层钢绞线在实践中可保证较高的有效预应力;②对锚具槽进行分级分步张拉,可使内衬混凝土获得较均匀的封闭环向压应力环,平均压应力达-10.9 MPa;③提出的3项控制指标可进行量化管理,结合自动张拉技术可有效地保证张拉质量。

This study focuses on improving stress distribution and preventing crack formation during the tensioning process.To achieve this,we conducted full-scale model test and proposed a tension sequence and quality control indexes.Initially,we calculated the friction coefficient based on steel strand friction test.Subsequently,we applied the tension sequence and quality control indexes using an automated tension system.To monitor stress changes,we used elastomagnetic sensors for the steel strand,and strain gauges for the lining concrete.Field tensile tests yield the following key findings:1)The steel strand experiences a prestress loss of approximately 16.3%.However,by utilizing double-layered steel strands,we ensure a highly effective prestress in practical applications.2)Applying the proposed tension sequence in the anchorage slots results in the lining concrete achieving a relatively uniform annular compressive stress,with an average compressive stress of-10.9 MPa.3)The three control indexes we recommend can be quantitatively managed,and when combined with automated tension technology,they effectively guarantee the quality of tension.