盐腔内回填碱渣沉降固结特性室内试验研究

碱渣回填到充满卤水的废弃盐腔后,颗粒会自由沉降到盐腔底部形成沉积层,进而在自重作用下固结。为了解盐腔内回填碱渣的沉降固结特性,以江苏淮安地区碱渣为对象,进行了沉降柱试验和固结试验。试验结果表明:(1)碱渣在卤水中的沉降过程可以分为3个阶段:絮凝阶段、沉降阶段和固结阶段。初始浓度对碱渣的沉降曲线和沉降速率有很大的影响。(2)碱渣颗粒分布、密度、含水率和孔隙比均呈现出分层特性,颗粒粒径、密度随深度的增加而增大,含水率、孔隙比随深度的增大而减小。(3)碱渣具有很高的压缩性,压缩系数a1-2为3.36 MPa-1。在压力范围小于100 kPa下,固结系数随固结压力的增加而显著减小。试验结果对了解盐腔内回填碱渣的沉降固结特性提供了参考,有利于指导回填施工工艺和碱渣的后期处理。

Laboratory test study of sedimentation and consolidation behaviors of alkali waste backfill in salt caverns

When backfilled to abandoned salt caverns full of brine, alkali waste particles will settle freely and form a sediment layer at the bottom of salt caverns. This layer may consolidate further under its own weight. In order to understand the sedimentation and consolidation behaviors of alkali waste backfill in salt caverns, settling column tests together with oedometer tests are conducted on alkali waste from Huai'an in Jiangsu province. Test results show that: (1) The settling process of alkali waste in brine can be divided into three stages: flocculation stage, settling stage and consolidation stage. The settling curve and settling rate are significantly affected by the initial concentration. (2) The particle size distributions, density, water content and void ratio of alkali waste all show layered characteristics. The particle size and density increase with depth, the water content and void ratio decrease with depth. (3) The alkali waste has a very high compressibility; and the value of a1-2 is 3.36 MPa-1. The consolidation coefficient of alkali waste decreases significantly with an increase of consolidation pressure in stress range of less than 100 kPa. The test results are important for the study of sedimentation and consolidation behaviors of alkali waste backfill in salt caverns, and they can used to guide the backfill construction technology and reinforcement processing of alkali waste.