含水率对砂岩动态拉伸强度的影响

Influence of Moisture Content on Dynamic Tensile Strength of Sandstone

工程中的岩石具有不同的含水性,研究不同含水率岩石动态力学性质的变化规律,对岩石工程的设计和建设具有很强的指导意义。为研究不同含水率对砂岩动态拉伸强度的影响,利用霍普金森压杆(SHPB)试验装置对不同含水率试样进行了一系列动态巴西劈裂试验,研究了不同含水率砂岩在不同加载率条件下的动态拉伸强度变化规律。试验结果表明:岩石的动态拉伸强度随着加载率的增加而增加,其率相关性与含水率有关,饱和试样的率相关性较强,而干燥岩石的动态强度对加载率的变化不敏感。当加载率较低时,岩石的拉伸强度随着含水率的增加而降低;当加载率较高时,由于水的Stefan效应,水对岩石裂纹产生抗力,阻碍其扩展,导致岩石强度增加,饱和试样的动态拉伸强度出现高于非饱和试样强度的现象。

The rocks in the project have different water content.It is important for the design and construction of rock engineering to carry out research on the dynamic mechanical properties of different water content rocks.In order to study the effect of different moisture content on the dynamic tensile strength of sandstone,a series of dynamic Brazil split tests were carried out for the samples in different moisture content by using the Hopkinson pressure bar(SHPB)test device,and the dynamic tensile strength change rule of sandstone with different moisture content under different loading rates was studied.Experimental results show that:The dynamic tensile strength of the rock as loading rate increases,rate dependence is related to the moisture content,rate dependence of saturated sample is stronger,while the dynamic strength of the dry rock is not sensitive to the change in rate of loading.When loading rate is lower,the tensile strength of the rock decreases with the increase of moisture content.When loading rate is higher,because the water Stefan effect results in that the resistance to rock crack generated by the water impeded its expansion,which leads to the increase of rock strength,so that the dynamic tensile strength of saturated sample is higher than that of unsaturated sample.