后注浆抗压桩受力性状的试验研究

 在温州鹿城广场5根抗压桩静载试验的基础上，揭示后注浆抗压桩在不同荷载水平下的一些规律。试验表明，注浆压力时刻都在变化，但有一个大体动态变化的范围。注浆可以固化桩底沉渣和桩侧泥皮，改善桩的承载性能。抗压桩在荷载作用下，桩身轴力随着深度的增加而减少，且随着荷载的增加，桩端轴力逐渐增大。对持力层是卵石层的桩采用桩端后注浆技术后，桩身压缩量占单桩沉降的80%以上。桩侧摩阻力的发挥程度和桩土相对位移有着很好的对应关系。当桩土相对位移达到一定值后，桩上部土层会出现桩侧摩阻力随着桩顶荷载的增加而减少的现象，即侧摩阻力软化现象。而靠近桩端的桩侧土体，尽管桩土相对位移较小，桩侧摩阻力值却会急剧增大。

EXPERIMENTAL STUDY ON MECHANICAL PROPERTIES OF POST-GROUTING COMPRESSIVE PILE

Based on the static tests of five compressive piles of Lucheng Square in Wenzhou City，some conclusions of post-grouting compressive pile under different loads are drawn. Although grouting pressure changes at any time，it has a dynamic variable range. Post-grouting technique can solidify bottom sediment and mud cake around pile，and improve the bearing capacity of pile. Axial force of compressive pile decreases with the increase of soil depth，and that of pile bottom gradually increases with increasing load. Compressive deformation of pile is the major part of settlement of single pile for scree stratum after grouting，which accounts for over 80%. The developing degree of side resistance is well corresponding to the relative displacement between pile and soil. When the relative displacement between pile and soil increases to a certain value，the side resistance will decrease with the increase of load，i.e. side resistance softening phenomenon happens. Though very little relative displacement between pile and soil occurs，the side resistance of soil close to pile bottom will increase sharply.