网纹红土分级加载与分别加载蠕变试验研究

Research on creep of reticulate red clay under stepped-load and constant-load

由于试验条件的限制,目前国内外学者大都是采用分级加载对蠕变进行研究,而分别加载很少被采用。为了解决分级加载的土样硬化问题以便得出更符合工程实际的分别加载蠕变,本文对网纹红土未扰动土样进行了在分级加载条件下和分别加载条件下的初始加载、卸载、重复加载的单向固结蠕变试验。试验结果表明,网纹红土未扰动样在每级应力水平下都发生了明显的蠕变,蠕变随应力的增加而增加。对比两种不同加载条件的蠕变试验结果发现,无论是分级加载条件下还是分别加载条件下,网纹红土未扰动样的蠕变时间与蠕变变形的比值跟蠕变时间都存在线性关系;并且分级加载条件下这种线性关系的斜率与分别加载条件下线性关系的斜率也存在线性关系。对研究结果的分析表明,可以利用分级加载的蠕变变形的稳定值推算出分别加载的蠕变变形稳定值。

In soil creep tests a series of specimens or only one specimen is commonly used. In the former case, constant-load creep test will be performed; in the later case, step-load creep test will be conducted. Constantload creep tests eliminate the effect of loading conditions, making the test result more reliable. Since complete similarity among a number of specimens cannot be ensured, a significant spread of test data is unavoidable during tests of constant-load test. In order to solve the problem, undisturbed reticulated red clay specimens were tested under stepped-load and constant-load one-dimensional creep conditions with initial loading, unloading, reloading. The test results show that the undisturbed reticulated red clay specimens have obvious creep under each stress level in the initial loading, unloading and reloading under stepped-load and constantload; creep deformation increases with the increasing stress. Comparison of the test results shows that there is a linear relation between the ratio of creep time and creep strain and creep time in both the stepped-load and constant-load creep. Analysis of the comparison results show that stable values of the creep deformation under the stepped-load can be used to calculate those of constant-load.