冲击荷载下钙质砂侧限压缩及颗粒破碎试验研究

海洋动力环境中钙质砂受荷载时的压缩变形特性是工程建设考虑的重要因素。对1~2 mm粒径钙质砂在侧限条件下进行静荷加载、冲击加载、冲击后静荷加载试验,分析试样在三种加载方式下的e-P曲线,运用Hardin模型中的相对破碎率Br值对其颗粒破碎进行度量。试验结果表明:相同荷载幅值水平下,相对静荷加载,试样对冲击加载较为敏感,其压缩变形更加明显,颗粒级配变化更显著;冲击加载时,存在临界冲击次数N_(cr),此时试样孔隙比趋于稳定;且冲击荷载幅值越大,相应临界冲击次数N_(cr)值越大;同时发现冲击加载会影响试样压缩性,冲击加载时试样颗粒破碎程度越高,冲击加载后静荷加载时表现的压缩性越低,颗粒相对破碎率B_r值变化越小,试验结论对工程建设具有一定参考意义。

Experimental study of comfined compression and particle breakage of calcareous sand under impact load

The compression deformation properties of calcareous sand under load in the ocean dynamic environment is an important factor to consider. The static load,impact load and static load after impact were carried with the calcareous sand particle samples the diameter of which are within 1~2mm under unconfined conditions.The e~p curve of calcareous sand is determined under three different loading methods. The relative breakage,Br value,in the Hardin model is used to measure particle breakage. The test results show that the calcareous sand samples are more sensitive to the impact load compared with the static load and is more distinct in compressive deformation under the same overload amplitude;there exists a critical number of impact,Ncr,when sample void ratio has been stable.The greater the amplitude of impact load,the larger the value of Ncr.The results also shows that impact load could influence the compressive property of samples; the higher particle breakage degree the samples are in under impact load,the lower compression degree the samples showed under static load after impact load,and the samller the relative breakage,Br value,changes.The conclusion has a certain reference significance to engineering construction.