含水率对相似材料模型强度的影响规律

Influence of moisture content on strength of similar material models

为减少含水率对相似材料模型强度的影响,利用时域反射技术对相似材料模型含水率变化特征进行了监测,通过不同含水率值的相似材料试件,获得了相似材料试件单轴抗压强度与含水率的关系;提出克里金空间插值法的估值公式计算相似材料模型含水率,得出了含水率变异函数表达式;以哈拉沟煤矿12101工作面为研究对象,搭建了长×宽×高为1 000 mm×120 mm×700 mm的相似材料模型,利用FDR传感器监测模型含水率,绘制模型含水率分布图。结果表明,当配比为8∶3∶7且含水率在0.2%~2.3%之间时,相似材料试件的单轴抗压强度与其含水率呈负线性关系;通过模型含水率分布云图,模型竖直方向含水率呈上低下高的梯度特征,中硬度岩石相似材料模型含水率值达到1.7%~2.2%时,模型强度达到预期强度;相似材料模型干燥后期模型上部强度大于预期强度,中下部基本一致。提出了一种利用含水率特征值来预判模型干燥养护程度的方法,为提高相似材料模型试验准确性提供方法参考。

In order to reduce the influence of moisture content on the strength of similar material models,the change characteristics of moisture content of similar material models were monitored by frequency domain reflectometry.The relationship between the water content of similar materials and the uniaxial compressive strength was obtained through the test of similar materials with different moisture content values.A Kriging space interpolation formula is presented to calculate moisture content values between the measured moisture content locations.A function expressing the variation of moisture content in the physical model is given.Taking the 12101 working face of Halagou coal mine as the research object,a similar material model of 1 000 mm×120 mm×700 mm was constructed;the water content of the model was monitored by FDR sensor to draw the water content distribution map of the model.The results show that when the ratio is 8∶3∶7 and the moisture content is between 0.2%and 2.3%,the uniaxial compressive strength of the specimens of similar materials meets a negative linear correlation with the content.Through the model water content distribution cloud map,the model moisture content shows vertical gradient characteristics in the vertical direction.When the moisture content of the model constructed with materials similar to medium hardness rock reaches 1.7%~2.2%,the strength of the model reaches the expected strength.In the later stage of drying,the upside’s strength of model is greater than the expected strength,and the middle and lower parts are basically the same.A method for predicting the dryness of the model by using the eigenvalue of moisture content is proposed,which provides a method reference for improving the accuracy of model test of similar materials.