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我国南方一座较高土坝的心墙采用了石灰岩风化洪积红粘土填筑,原设计填筑标准为干容重1.55克/厘米~3,合格率90％,含水量21～24％,用15吨羊足碾,压24遍,每层压实土厚度8～10厘米.料場天然含水量30％左右,用农业机耕方法逐层水平开采,翻晒碎土后上坝.1964年汛前施工中发现生产效率低,经常发生干松土层、光面、剪力破坏、结合不良等质量事故,还有雨后浸水分层现象,经常返工,对施工进度与质量都有很大影响.为了解决这些问题,曾进行了试验室及现場碾压试验,证明将填筑干容重降低互1.50或1.51克/厘米~3,含水量提高到24～28％,仍能满足稳定及防渗要求,而填土塑性、均勻性及耐水性有显著改善,基本上可解决施工中发生的一些质量事故,并通过现場碾压试验确定了相应的施工方法及压实参数,在工程上已实际采用.现場碾压实验中也表明气胎碾比羊足碾压实有显著的优点,可进一步提高施工含水量,有可能在料場使用立采工艺,解决汽车运土上坝与羊足碾碾压之间的矛盾,工效高,有利于坝壳与心墙平起,压实质量较均匀等,结合面质量也能满足要求,建议推广使用.
The core wall of a higher earth dam in southern China is filled with red clay with limestone weathered red clay. The original designed filling standard is 1.55 g / cm 3 for dry bulk density, 90% pass rate and 21-24% moisture content. Foot grind, pressure 24 times, each layer of compacted soil thickness of 8 to 10 cm. Material yard natural water content of about 30%, with agricultural tillage method level by level mining, turning the ground after the dam on the dam .1964 construction found before the flood Low productivity, often dry loose soil, smooth, shear damage, combined with poor quality accidents, there are stratification after rain submergence, often rework, the construction progress and quality have a great impact.In order to solve these Problem, had carried out laboratory and on-site rolling test proved that the filling capacity to reduce the weight of each 1.50 or 1.51 g / cm3, water content increased to 24 to 28%, still able to meet the requirements of stability and seepage, and Soil plasticity, uniformity and water resistance significantly improved, basically to solve some of the quality of the accident occurred during the construction, and through on-site rolling test to determine the appropriate construction methods and compaction parameters, the project has been actually adopted. In-situ rolling experiments also showed that pneumatic tire grind was more compact than sheep grind The advantages of this method can further improve the water content of the construction and it is possible to use the vertical mining technology in the stockyard to solve the contradiction between the roller embankment and the sheep foot rolling on the truck. Compaction quality is more uniform, with the surface quality can meet the requirements, it is recommended to promote the use of.