修正双屈服面模型三维化在水泥砾质土中的应用

Modified double yield surface model revised by SMP criterion applied to cement-gravel soil

采用变换应力方法将空间滑动面破坏准则应用于修正双屈服面模型,使该模型合理三维化。在不增加新参数的情况下可描述水泥砾质土的力学特性,利用水泥砾质土三轴试验结果对三维化后的修正双屈服面模型进行初步验证。结果表明,在低水泥掺入比(wc≤5%)的条件下,三维化后的修正双屈服面模型能够较好地反映水泥砾质土应力~应变关系的软化现象,且充分体现了体变~应变关系在低围压下的剪胀性和高围压下的剪缩性;但当水泥掺入比wc为8%且围压为200 k Pa时,水泥砾质土的脆性显著增强,其剪胀性也十分显著,水泥砾质土达到峰值强度后呈现脆性破坏,导致该模型计算值与试验值误差较大。该研究成果可为水泥砾质土应用于高土石坝心墙料力学特性研究提供一定的技术支撑。

Spatially mobilized plane(SMP) criterion is applied to modified double yield surface(MDYS)model using a transformed stress tensor method. Thus the failure and yield criterion of MDYS model isSMP instead of Mises yield criterion. Using this method,mechanical properties of cement-gravel soil is re-flected without increasing original model's parameters. The MDYS model is verified preliminarily by triaxialcompression test of cement-gravel soil. The results show that the MDYS model can reflect softening phenom-ena of cement-gravel soil under cement mixing ratio less than or equal to 5 %. It is fully reflected forshear dilatation under low confining pressure and shear contraction under high confining pressure of cement-gravel soil in the MDYS model. There is large error between calculated and experimental values because offriability and dilatanay when cement mixing ratio is equal to 8 % and confining pressure is 200 k Pa. The re-search results can provide technical support for mechanical properties research of cement-gravel soil appliedto the core material of high earth-rockfill dam.