高含水量黏土压实特性与填筑试验研究

Study on Compaction Characteristics and Filling Test of High Water Content Clay

由于天然含水量远高于最优含水量,高含水量黏土无法通过晾晒方式按现行技术标准的规定控制压实含水量,导致压实质量不符合要求。依托±800 kV布拖换流站工程,采取室内土工试验、现场压实试验、现场强夯置换试验等方式分别研究了高含水量黏土的压实特性、填筑方式和处理效果。压实特性研究表明,以②_3层黏土为代表的高含水量黏土直接分层压实的压实系数仅为0.64~0.70,以其构筑填方地基时必须采取处理措施。现场压实试验表明,以碎石为外掺料进行物理改良时,掺量29%、38%、46%的试验组压实系数检测结果均低于0.94;以生石灰为外掺料进行化学改良时,掺量19%、23%、29%的试验组压实系数检测结果均低于0.94;将压实控制标准降至0.90后,碎石掺量46%的振动碾压试验组、冲击碾压试验组和生石灰掺量29%的振动碾压试验组符合要求。现场强夯置换试验表明,采用3000 kN·m能级和4 m堆填厚度的强夯置换复合地基承载力特征值达到152 kPa,夯点、夯间的均匀性较好,满足工程使用要求。

As the natural water content is far higher than the optimal water content,the high water content clay can’t control the compaction water content by the way of air drying according to the existing technical standards,resulting in compaction quality unqualified.Based on±800 kV Butuo converter station project,the compaction characteristics,filling method and treatment effect of high water content clay were studied by ways of indoor geotechnical test,field compaction test and field dynamic replacement test.Research on compaction characteristics shows that,the compaction coefficient of high water content clay represented by②3 layer is only 0.64~0.70,and the treatment measures must be taken when the filling foundation is constructed with it.The field compaction test shows that the test results of the compaction coefficient of the test group with 29%,38%and 46%crushed stone as the admixture are lower than 0.94,the test group with 19%,23%and 29%quicklime as the admixture are also lower than 0.94.And if the compaction control standard reduces to 0.90,the vibration rolling test group and the impact rolling test group both with 46%gravel content,the vibration rolling test group with29%quicklime content could meet the requirements.The field dynamic replacement test shows that the characteristic value of bearing capacity of composite foundation with 3000 kN·m energy level and 4 meters filling thickness reaches 152 kpa,and the uniformity of compaction point and outside is good,which meets the engineering requirements.