注入初期盾构壁后注浆体的三轴试验研究

壁后注浆体注入初期的变形及力学性质的变化直接影响到土体应力释放、地面沉降以及管片的后期受力情况。基于非自立性材料三轴试验方法,以工程常用的硬性浆和惰性浆为研究对象,开展了三轴固结不排水剪切试验。结果表明:高围压有助于浆液排水固结,且浆液最终体应变也随着围压增加而增大;浆液在不排水条件下剪切过程呈现出应变硬化性,体积先收缩,随后呈现出明显的剪胀特性。在满足变形及施工要求的前提下,适当提高注浆压力及采用水胶比较小的浆液,有利于保证注浆体的施工质量。

Experimental Study on the Triaxial Test of the Shield Backfill Grouting Material at Initial Stage

Deformation and mechanical properties of backfill grouting material directly affect soil stress release,ground subsidence and late stress situation of segment lining.Based on triaxial test method of non-independent material,we take the rigid slurry and inert slurry as research objects,carrying out consolidated non-drained triaxial shear test.Results show that,1)high confining pressure contributes to the consolidation and drainage of the slurry,and the ultimate volumetric strain of the slurry increase with confining pressure;2)in the shearing process on the non-drained condition,slurry shows tendency of strain hardening,and the volume shrinks first,then with obvious shear dilatation.On the premise of deformation and construction requirements,we can suitably increase grouting pressure and use slurry with smaller water-glue ratio to ensure the construction quality of grouting body.