粉煤灰基UEA改性注浆材料力学特性与失稳模式

采用PC42.5硅酸盐水泥、粉煤灰、UEA膨胀剂研制粉煤灰基UEA改性注浆材料，在实验室通过刚性试验机对15个不同配比浆液结石体养护期下缩量测定与单轴抗压强度力学实验，研究粉煤灰基UEA改性注浆材料的自然变形、力学特性与失稳模式。通过单轴压缩试验分析了UEA掺量对浆液结石体下缩量、破坏强度、峰值应变及破坏形态的影响，确定了粉煤灰基UEA改性注浆结石体失稳模式与临界值点。结果表明：随着UEA掺量梯度增加(0‰、2‰、4‰、6‰、8‰)，以UEA掺量0‰为对照梯度，结石体初始下缩量分别下降41.55%、2.63%、1.77%、2.22%，结石体后期下缩量降幅分别为45.61%、61.29%(C0、C1、C2)，结石体破坏强度分别提升49.15%、提升3.96%、下降18.18%、提升4.95%，整体表现出升高—降低—缓高的形态，结石体峰值应变分别提升1.66%、1.41%、4.37%、1.70%，UEA膨胀剂对浆液结石体峰值应变具有明显提高作用，表现出线性升高趋势|粉煤灰基UEA改性注浆体破坏失稳模式表现为低强度大变形复杂破坏与高强度小变形破坏两种，两种失稳模式划分临界值点为浆液结石体破坏强度1.5MPa。

Mechanical properties and instability mode of fly ash based UEA modified grouting material

Using #425 Portland cement, fly ash and UEA expansive agent to develop fly ash based UEA modified grouting material, the shrinkage measurement and uniaxial compressive strength mechanical experiment of 15 grouts with different ratios during curing period were carried out in the laboratory by rigid testing machine to study the natural deformation, mechanical properties and instability mode of fly ash based UEA modified grouting material. The uniaxial compression test is carried out, the influence of UEA content on the shrinkage, failure strength, peak strain and instability mode of grouts is analyzed, and the instability mode and critical value point of fly ash based UEA modified grouts are determined. The results showed that with the increase of UEA content gradient (0 ‰, 2 ‰, 4 ‰, 6 ‰, 8 ‰), the initial shrinkage of stone body decreased by 41.55%, 2.63%, 1.77% and 2.22% respectively, and the later shrinkage of grouts decreased by 45.61% and 61.29% respectively (C0, C1 and C2); With the change of UEA content gradient, the failure strength of the sample increased by 49.15%, increased by 3.96%, decreased by 18.18% and increased by 4.95% respectively; With the change of UEA content gradient, the peak strain of stone body increased by 1.66%, 1.41%, 4.37% and 1.70% respectively. UEA expansive agent significantly increased the peak strain of grouts, showing a linear increasing trend; The failure and instability modes of fly ash based UEA modified grouts are low-strength large deformation complex failure and high-strength small deformation failure. The critical point of the two instability modes is that the failure strength of slurry stone body is 1.5MPa.