充填体分级加载蠕变试验及模型参数智能辨识

Study on Creep Properties of Backfill Under Step Loading and Intelligent Identification of Constitutive Model Parameters

为研究充填体在荷载作用下的长时稳定性,对充填体进行单轴分级蠕变试验,研究其蠕变特性。由胶结充填体单轴分级蠕变曲线,采用陈氏数据处理方法绘出试块分别加载蠕变曲线,试验结果表明:充填体具有显著的蠕变行为包括瞬时变形、衰减蠕变阶段、等速蠕变阶段,受荷载及时间所限并未出现加速蠕变阶段;瞬时应变与荷载成线性函数关系、蠕变速率随时间增长而逐渐降低至定值,显示出充填体具有同岩石类似的蠕变特性。充填体的蠕变特性符合Burgers模型,采用具有多点寻优、全局最优解等优点的遗传算法对不同应力水平下的Burgers模型参数进行了智能辨识,结果表明,蠕变试验曲线与理论曲线吻合较好,Burgers可较好的描述胶结充填体的蠕变特性。

In order to study the long-term stability of backfill under the loading, the creep characteristics were studied by single axis creep tests on backfill. By the uniaxial creep curves under step loading of backfill and Chen^s data pro- cessing method of specimens, each loading creep curve was plotted. The results indicated that the backfill had obvious creep behaviors, including instantaneous deformation, decay creep stage and steady creep stage, but accelerated creep stage was not involved due to the limit of time and load. The instantaneous strain and stress had a linear function relation-ship, and the creep rate decreased with the time increasing. It reflected that the creep characteristics of backfill were similar to that of such rock, and were in accordance with the Burgers model. Intelligent identification of Burgers model parameters under different stress levels was carried out by u- sing genetic algorithm with the advantages of multi point op- timization and global optimization. The results showed that the creep test curves matched well with the theoretical curves, and the Burgers model can acceptably describe the creep characteristics of backfill.