真空预压加固吹填流泥强度增长规律试验研究

Experimental study on strength increasing rule of hydraulic fill mud consolidated by vacuum preloading

结合对真空预压的理论认识和工程实践,通过试验对真空预压加固吹填流泥的孔隙水压力、泥面沉降、出水量、含水率、强度参数的变化特征进行分析。试验结果表明:真空预压前期泥面沉降增长迅速,而孔隙水压力增长缓慢;真空预压后期泥面沉降增长缓慢,而孔隙水压力增长较快。分析了真空预压加固吹填流泥强度增长机理,运用有效固结应力法强度增长计算公式结合监、检测数据推算吹填流泥强度增长过程。计算结果表明:理论计算的强度增长规律符合现场实测强度增长规律;真空预压前期土体几乎无强度,真空预压中后期强度增长较快;且抽真空7个月土体强度增长趋势仍未趋于收敛。真空预压加固吹填流泥强度增长的这些特点在真空预压工程设计及施工中应引起重视,应综合考虑强度增长规律及工程经济合理性确定预压时间,并以强度指标作为卸载标准之一。

Based on the theoretical knowledge and engineering practices about vacuum preloading at present,this paper analyzed the change features of parameters including pore water pressure, mud surface settlement, wateryield, moisture content and strength of the hydraulic fill mud consolidated by vacuum preloading through test.The testresults show that at the earlier stage of vacuum preloading, the surface settlement increases fast, but the pore waterpressure increases slowly; in contrast, the surface settlement increases slowly and the pore water pressure increases fastat the later stage. The strength increasing mechanism of hydraulic fill mud consolidated by vacuum preloading wasanalyzed, and the strength increasing process of hydraulic fill mud was calculated by applying the calculation formulafor the strength increase under effective stress consolidation, and combing with monitoring and testing data. Thecalculation results show that the strength increasing rule calculated with theory corresponds to the strength increasingrule practically measured in the experiment; the strength of hydraulic fill mud is nearly not existed at the earlier stageof vacuum preloading, but increases relatively fast in the middle and later stages of vacuum preloading; The strengthincreasing trend of soil mass still doesn＇ t tend to disappear after 7 months＇ vacuum preloading.These characteristicsabout the strength increase of hydraulic fill mud consolidated by vacuum preloading should be brought to the attentionin the design and construction of vacuum preloading engineering. The preloading period should be reasonablydetermined by comprehensively considering the strength increasing rule and the rationality of engineering economy,and the strength index shall be regarded as one of unloading standards.