水下基础防冲刷袋装干混料配制技术的试验研究

Experimental study on preparation technology of anti scour bagged dry mixture for underwater foundation

针对东海大桥水下基础防冲刷的技术要求,开展袋装干混料配制技术研究。采用水泥和骨料等原材料,研究了水泥用量、砂率和骨料粒径对干混料表观密度和抗压强度的影响,并选用编织土工袋,在东海海域进行干混料现场验证试验。试验结果表明,水下硬化干混料7 d的表观密度大于2200 kg/m^(3),7 d抗压强度大于5 MPa;随着干混料水泥用量的增加,干混料抗压强度不断增加,水泥用量为260 kg/m^(3)时,干混料的30 d抗压强度可达到10 MPa;试块法测试的抗压强度与钻芯法测试的抗压强度偏差小于10%,可用于测试干混料的抗压强度;水泥用量、砂率和骨料粒径对干混料的性能产生明显影响,提出了干混料的水泥用量、砂率和粗骨料级配等配合比参数。现场验证试验结果与室内试验结果是一致,可满足工程设计要求。

According to the technical requirements of anti scour for underwater foundation of Donghai Bridge,the preparation technology of bagged dry mixture was studied.The effects of cement dosage,sand ratio and aggregate size on the apparent density and compressive strength of dry mixture were studied by using cement and aggregate.The woven geotextile bags were selected to carry out the field verification test of dry mixture in the East China Sea.The test results show that the apparent density of the underwater hardened dry mixture is greater than 2200 kg/m^(3) for 7 d,and the compressive strength is greater than 5 MPa for 7 d.With the increase of the cement content of the dry mixture,the compressive strength of the dry mixture increases continuously,and the 30 d compressive strength of the dry mixture can reach 10 MPa when the cement content is 260 kg/m^(3).The deviation between the compressive strength measured by the test block method and the compressive strength measured by the core drilling method is less than 10%,which can be used for testing the compressive strength of dry mixture,cement dosage,sand ratio and aggregate size have obvious influence on the performance of dry mixture.The mixing ratio parameters of dry mixture,such as cement dosage,sand ratio and coarse aggregate gradation,are put forward.The field test results are consistent with the indoor test results,which can meet the engineering design requirements.