Abstract: The shape of the calcareous sand is often irregular, porous and it is fragile due to its unique biological origin. The influence of the particle shape on the permeability is a question worth of further evaluation. Therefore, this paper selected the calcareous sand and shelly sand of the same grain size distribution and the shape parameters of the two samples through PartAn3D particle morphology measurement were determined. The void ratio was used as the control parameter to perform conventional permeability tests and to compare and analyze the impact of particle shape on the permeability, which initially explained the difference in the permeability caused by the particle shape. The test results show that the length-to-thickness ratio, Pval, and the concavity degree of the calcareous sand sample are smaller than those of the shelly sand sample, while the roundness, sphericity and the circularity are larger than those of shelly sand samples. With the same relative density, the permeability of calcareous sand sample is greater than that of the shelly sand sample. In the medium relative dense samples, the hydraulic conductivity values of the calcareous sand sample and the shelly sand are close to a small difference. In dense samples, the difference in the hydraulic conductivity of the calcareous sand sample and the shelly sand sample decreases with the increase of the relative density. In terms of the influence of the void ratio on the permeability of two different types of samples, when the void ratio is less than 1.45, the hydraulic conductivity increases slowly with the increase of the void ratio; when the void ratio is greater than 1.45, the hydraulic conductivity increases significantly with the increase of the void ratio. Under the same void ratio conditions, the hydraulic conductivity of the calcareous sand sample is greater than that of shelly sand sample, and the difference increases with the increase of void ratio. The reason why the hydraulic conductivity of the calcareous sand sample is greater than that of shelly sand sample under the same void ratio might be explained by the difference in the head loss when the water flows through the sand column per unit length. This difference might be caused by the different particle shape. 

Key words: hydraulic conductivity, particle shape, void ratio, relative density