磷石膏胶结充填体动态力学特性研究

Study on Dynamic Mechanical Characteristics of Phosphogypsum Cemented Filling Body

为了研究凿岩爆破对不同磷石膏新型砂浆配比和不同养护时间的磷石膏胶结充填体稳定性的影响,利用Hopkinson压杆实验装置,以不同加载速度轴向冲击充填体试样,对其动态力学性能进行了研究,分析了动态冲击下充填体的波形曲线、应力—应变曲线,动态抗压强度、强度增强因子(DIF)与平均应变率的关系。结果表明:磷石膏胶结充填体的波阻抗较小,能够对应力波产生阻尼作用;在相同配比和相同养护时间下,不同应变率的充填体应力—应变曲线的下降段基本一致,而上升段差异较为明显;随着应变率的提高,上升段曲线随之平缓;动态抗压强度和DIF均随着平均应变率的增加而增加,且均能用多项式函数分别来描述动态抗压强度、DIF与平均应变率之间的关系。

In order to study the influence of rock drilling and blasting on the stability of phosphogypsum cemented filling body with different phosphogypsum-to-the new mortar ratios and different curing times,the dynamic mechanical properties of the phosphogypsum cemented filling body were studied.By using the Hopkinson pressure bar(SHPB)experimental device to axially impact filling body at different loading speeds,the waveform curves,stress-strain curves,dynamic compressive strength,dynamic increase factor(DIF),the failure modes,and the relationship between the average strain rate of the filling body and the ratio of the filling materials were analyzed.The results show that the wave impedance of the phosphogypsum cemented filling body is small and can dampen the stress wave.Under the conditions of the same ratio,same curing and different strain rates,the descending section of the stress-strain curve of the filling body is basically the same,while the difference in the ascending section is more obvious.For the group with the highest static compressive strength,the growth rate of stress increases rapidly with the increase of strain,while the dynamic compressive strength and DIF both increase with the increase of the average strain rate,and the relationship between the dynamic compressive strength,DIF and average strain rates can be described by polynomial functions.When the curing time is the same,with the increase of the new phosphogypsum mortar ratio,the dynamic compressive strength and DIF of the filling body decrease,and relationship between the dynamic compressive strength of the filling body,DIF and the new phosphogypsum mortar ratio presents a polynomial function.When the proportion of new phosphogypsum mortar is the same,with the increase of curing time,the dynamic compressive strength and DIF of the filling body increase,and the dynamic compressive strength and DIF of the filling body have a polynomial function relationship with the curing time.When the average strain rate is less than 100 s-1,the fractured shape of the fillings is blocky,and when the average strain rate reaches 300 s-1,the fractured shape of the filling body is already powdery,indicating that the critical value of the average strain of the phosphogypsum cemented filling body is between 100 s-1 and 300 s-1.When the proportion of new phosphogypsum mortar is the same,the longer the curing time is,the lower the pulverization degree of the filling body is.When the curing time is the same,the larger the proportion of new phosphogypsum mortar,the higher the pulverization degree of the filling body.