粉质黏土填料在K30试验加载进程中的变形时间效应状态分析

变形稳定标准和分级加载制度是影响K30试验效率和准确性的关键因素，与加载进程中填土的变形时间效应状态密切相关。开展了3组最优含水率下压实系数K分别为0.90、0.95和1.00填土模型的小型平板载荷试验，获得了不同荷载作用下填土变形时程曲线和弹塑性变形数据，讨论了在K30试验加载进程中填土变形状态的变化及其对加载稳定时间的影响。试验表明：良好压实的粉质黏土填料，在K30试验进程中的变形以弹性为主，处于缓慢收敛状态，随着加载级数增加，塑性变形比例逐渐增大，变形时间效应呈现出由微弱进入明显状态的演化趋势，变形1.25 mm对应于缓慢收敛中的微弱时间效应亚状态；“变形速率不超过0.01 mm/min”变形稳定标准分级加载时间随时间效应指数呈加速增长规律，能在保证试验精度的基础上提高试验效率；以最大荷载下填土变形时间效应不应超过显著状态、变形量不小于1.25 mm为约束条件，针对5级加载、0.04 MPa荷载增量的加载制度，可得K30试验的适宜范围为60～160 MPa/m。

Analysis of deformation time effect of silt clay filler in K_(30) loading process

The standard of deformation stability and the design of stepwise loading are the key factors affecting the efficiency and accuracy of K30 test, and closely related to deformation time-effect state of the filling in the loading process. To get time history curve and deformation data, three small plate loading tests of unit structure filling models are carried out in optimal water rate at compaction coefficient (K) of 0.90, 0.95 and 1.00. The change of the deformation state of the soil during the loading process of K30 test and the influence of the loading stability time are discussed. The results indicate that, the deformation of well compacted silty clay filler in the process of K30 test is mainly elastic, and almost in state of slow convergence. With the increasing of load, the ratio of plastic deformation gradually develops, and the evolution trend of deformation state is presented from weak to strong. When accumulated to 1.25 mm, the deformation is in the sub-state of weak in slow convergence. The standard of “0.01 mm/min”, step-loading time of which shows accelerating growth pattern, can apparently reduce test time with acceptable test error. On the principle that the deformation state should be in apparent state during loading process, and deformation should exceed 1.25 mm, for loading system of five steps and 0.04 MPa load increment, it is suggested that the K30 value in the detection of compaction quality of fine grained soil filler should be between 60-160 MPa/m.