氯盐腐蚀对充填膏体蠕变特性影响的试验研究

为探索充填膏体在经过不同时长氯盐腐蚀后的蠕变规律,采用饱和氯化钠(NaCl)溶液,对养护28天的充填膏体进行干湿循环加速腐蚀试验。采用TAW2000型岩石三轴试验机,将未经腐蚀的试件和经过不同时间腐蚀的试件分别进行不同应力水平的三轴蠕变试验,并对试验结果进行对比分析。在试验基础上,建立了氯盐腐蚀条件下充填膏体的蠕变模型。将一个应变触发的非线性粘壶串联在原来的Poynting-Thomson模型上,建立了一个改进Poynting-Thomson模型。研究表明:在腐蚀早期,经过腐蚀的充填膏体蠕变变形较之未经腐蚀的小;随着腐蚀时间延长,充填膏体的蠕变变形逐渐增大;在长时间腐蚀、高应力水平同时存在的条件下,充填膏体会出现加速蠕变现象。本文建立的蠕变模型与蠕变试验数据吻合较好,能够反映出充填膏体在氯盐腐蚀作用下的蠕变特征。

Experimental Study of the Influence of Chloride Corrosion on Creep Properties of Filling Paste

In order to explore the creep properties of a kind of filling paste subjected to chloride corrosion of different time length, taking sodium chloride (NaCl) saturated solution as the chloride, a series of wet-dry cyclic accelerated corrosion experiments were carried out for filling paste maintained for 28 days. Adopting TAW2000 triaxial rock test machine, triaxial creep experiments at different stress levels were conducted for uncorroded specimens and specimens corroded of different time legnths, respectively. Based on experimental results, which were comparatively analyzed, a creep model of filling paste was established under chloride corrosion condition. An improved Poynting-Thomson model was established by connecting in series a strain triggered nonlinear dashpot to original Poynting-Thomson model. Study finds that in the early period of corrosion, the creep deformation of corroded filling paste is smaller than that of uncorroded filling paste. With the corrosion time increases, the creep deformation of filling paste gradually enlarges. When both the long time corrosion and the high stress level exist simultaneously, filling paste presents accelerated creep deformation. The creep model presented in this paper is in a good agreement with experimental data, and can reflect creep characteristics of filling paste subjected to chloride corrosion.