砾质土心墙料蠕变对坝体应力变形的影响

Influence of gravel soil core wall's creep characteristics on the stress and deformation of dam

针对砾质土蠕变特性的研究成果较少,原因在于砾质土含有大量渗透性较低的细粒,大试样固结排水效果差,难以获得较好的蠕变试验成果。采用在砾质土大型三轴试样中钻孔灌砂以加速试样的排水固结的方法,进行了某高土质心墙堆石坝砾质土心墙料的蠕变试验,获得了砾质土心墙料的蠕变模型及参数,建立了高心墙坝的三维有限元模型,采用非线性有限元研究了砾质土心墙料蠕变特性对坝体应力变形的影响。研究成果表明:九参数幂级数蠕变模型能较好地描述砾质土的蠕变特性;上、下游坝壳的蠕变对心墙自身变形的影响较小,需要在坝体应力变形计算中考虑心墙料蠕变的影响;当心墙料的蠕变速率快于周围堆石体时,蠕变效应会进一步增加心墙拱效应,反之,蠕变效应会减小心墙拱效应。

At present,there are limited findings on creep characteristics of gravel soil.A major reason is that the gravel soil contains a large number of fine particles with low permeability.Correspondingly,the consolidation and drainage effect of large sample is weak,which indicates non-reliable creep test results.In this paper,the creep test of a gravel soil used for a high earth core wall rockfill dam is carried out by using the drilling hole and filling sand method in the large gravel soil triaxial specimen to accelerate its drainage and consolidation effect.A creep model and related parameters of the gravel soil are acquired.A three-dimensional finite element model of high earth core wall rockfill dam is established.The influence of the creep characteristics of gravel soil core wall on the stress and deformation of the dam is studied utilizing a nonlinear finite element method.The results show that the creep model with nine parameters and power series has a better performance on describing the creep behavior of the gravel soil.The creep of the upper and lower dam shells has little effect on the deformation of the core wall.The creep effect of the core wall needs to be calculated in the stress and deformation of the dam.When the creep rate of the core wall is faster than that of the surrounding rockfill,the creep effect will further increase the core wall’s arching effect.On the contrary,the creep effect will reduce the core wall’s arching effect.