淤泥流变特性试验影响因素研究

Research on factors that influence rheological test results of mud

淤泥流变特性试验的剪切模式、样品的静置时间及温度等都会对试验结果产生影响。文章就淤泥流变特性试验影响因素进行了研究。研究结果表明:剪切率相同时,密度越大,剪应力则越大,样品密度测定须多次测量取平均值;样品密度越小,静置时间的影响越大,剪切率较低时,静置时间的影响较大,而当剪切率超过临界剪切率时,静置时间的影响变小,淤泥密度越小,静置时间影响的临界剪切率越大,流变试验时,静置时间应保持一致;随着样品温度的升高,对应的剪应力逐渐减小,在流变试验时,应保证各组次样品的温度一致;采用控制剪应力模式测得的数据相对稀少,剪切率较大时,采用控制剪应力模式测得的剪应力大于控制剪切率模式,而剪切率较小时,控制剪应力模式测得的剪应力则小于控制剪切率模式,在确定淤泥样品的低剪切率对应的屈服应力时宜采用控制剪应力模式,在对比不同淤泥样品的流变特性时,应当采用相同的剪切模式。

During the rheological test operation, some factors such as shear mode, standing time and the temperature of the sample may affect the results. Therefore, some research on factors that affect rheological test results of mud is done in this paper. It can be concluded as follows. When the shear rate is the same, the higher the density, the greater the shear stress is. Accordingly, it is recommended that the density of the sample must be measured several times and averaged. The effect of the standing time, which increases as the sample density decreases , is greater when shear rate is lower than a critical value, and then become insignificant when shear rate exceeds the critical value. Thus, the same standing time is recommended during the rheological test operation. The corresponding shear stress at the same shear rate decreases while the temperature of the sample is increasing. Accordingly , the samples for testing must be of the same temperature. The data measured with shear stress control mode, which are relatively sparse, are greater than those with shear rate control mode when the shear rates are relatively high, and conversely, on the contrary. Accordingly, it is more appropriate to choose shear stress control mode to determine the yield stress corresponding to low shear rate. And the same shear mode must be used when comparing the rheological properties of different mud samples.