不同注浆工况对砂土－混凝土接触面剪切特性影响

Effects of grouting conditions on shear behavior of sand-concrete interface

摘要:

为研究后注浆对土与结构物接触面力学特性的影响,采用自主研发的注浆装置和可注浆的大型直剪仪,通过3种注浆压力、3种注浆量和4种荷载工况下的共计22组后注浆砂土-混凝土接触面大型直剪试验,分析不同注浆工况和荷载工况对砂土-混凝土接触面剪切力学特性、剪胀（缩）性以及强度参数等的影响.结果表明:在注浆压力和法向应力一定的情况下,接触面峰值剪切应力随着注浆量的增大而增大,但随着法向应力的增大,增加注浆量对接触面力学特性的改善效果逐渐减弱；在注浆量和法向应力一定的情况下,注浆压力较低时,接触面峰值剪切应力变化不大,当注浆压力达到一定值,其对接触面峰值剪切应力提高效果较为明显；不同注浆和荷载工况下接触面抗剪强度增强系数介于1.1～2.0；浆液主要通过提高接触面等效黏聚力改善接触面力学特性,等效内摩擦角近似与未注浆接触面一致；接触面在未注浆工况下均发生剪缩,且最大剪缩量随着法向应力的增大而增大；后注浆能够转变较低法向应力下的接触面剪胀（缩）性；同一法向应力下,接触面最大剪胀量均随着注浆压力和注浆量的增大而增大,而最大剪缩量则随着注浆压力和注浆量的增大而减小.

Abstract:

To study the effect of post-grouting on the mechanical properties of the interface between soil and structure, a total of 22 groups of direct shear tests were conducted on samples with post-grouting sand-concrete interface under three grouting pressures, three grouting volumes, and four loading conditions. The influence of grouting conditions and loading conditions on the mechanical properties, shear dilation, and strength parameters of the sand-concrete interface were analyzed by using self-developed grouting equipment and grouting method. Test results show that the interface peak shear stress increased with the increase of grouting volume when the grouting pressure and normal stress remained unchanged. When the normal stress of the interface increased, the improvement effect of the grouting on the mechanical properties of the interface gradually decreased with the increase of the grouting volume. When the grouting pressure was low, the change of the interface peak shear stress was not obvious with the grouting volume and normal stress remained unchanged. When the grouting pressure reached a certain value, the increase of the interface peak shear stress was obvious. The shear strength enhancement coefficient of the interface was between 1.1 and 2.0 under different grouting and loading conditions. The shear behavior of the post-grouting sand-concrete interface was mainly improved by increasing the equivalent cohesion of the interface. The equivalent internal friction angle was approximately the same as that of the non-grouting interface. The shear contraction of the interface occurred under non-grouting conditions, and the maximum value of shear contraction increased with the increase of normal stress. Post-grouting could change the interface shear dilation mode for low normal stress. Under the same normal stress, with the increase of grouting volume and grouting pressure, the maximum value of shear dilation increased whereas the maximum value of shear contraction decreased.