高强高韧锚杆钢能量吸收特性研究

Study on energy absorption characteristics of high-strength and high-toughness steels used for rock bolt

在深部地下工程中,研发和应用新型金属支护材料越发引起人们的关注与重视,然而关于其在预应力和围岩加载过程中的能量吸收规律和特性尚不清楚,亟待进行相关研究。因此,基于晶体塑性方法,以新型高强高韧锚杆钢为例,比较分析不同金属支护材料的力学和能量吸收特性。同时采用以物理机制为基础的晶体塑性模型,研究不同预应力和围岩加载速率对高强高韧锚杆钢能量吸收特性的影响。研究结果表明,传统金属支护材料在能量吸收密度方面存在发展瓶颈。与传统金属支护材料的能量吸收密度与极限抗拉强度存在倒置关系不同,新型高强高韧锚杆钢在保持高强度(>940 MPa)和较大延伸率(>0.4)的同时,具有极高的能量吸收密度(>3.5×10^(8)J/m^(3)),是现有金属支护材料的3~7倍。晶体塑性模拟结果表明,通过调整预应力和控制围岩加载速率,可以进一步提高锚杆钢的能量吸收能力。例如,通过提高预应力可以快速提高材料的有效能量吸收速率,并能抵抗围岩加载速率的影响。当预应力增加至接近材料的屈服应力且围岩加载速率控制在10-2MPa/s以下时,可以使高强高韧锚杆钢获得最大的有效应变量(>0.54)和最高的有效能量吸收密度(>4.5×10^(8)J/m^(3)),充分发挥高强高韧锚杆钢的能量吸收特性。研究结果为高强高韧锚杆钢在高地应力支护工程上的应用提供理论依据和技术指导。

In deep engineering,the development and application of novel metallic materials has attracted many attentions.Although previous studies have demonstrated the importance and mechanical advantages of using high-strength and high-toughness steels in rock support system,its energy absorption characteristics under the influences of prestressing and rock loading remains still unclear.Therefore,based on the crystal plasticity method,this study takes novel high-strength and high-toughness bolt steel as an example to compare and analyze the mechanical and energy absorption characteristics of various metallic rock support materials.Meanwhile,the crystal plasticity model based on underlying physical mechanisms was used to study the effects of varying prestresses and rock loading rates on the energy absorption characteristics of high-strength and high-toughness bolt steel.The research results show that the development of energy absorption density of conventional metallic rock support materials meets a bottleneck.Distinct from the trade-off relationship between energy absorption density and ultimate tensile strength of conventional metallic rock support materials,the high strength(>940 MPa)and large elongation(>0.4)characteristics of novel high-strength and high-toughness bolt steel result in its extremely high energy absorption density of 3.5×10^(8)J/m^(3),which is about 3-7 times that of conventional metallic rock support materials.The results of crystal plasticity simulations show that the material’s energy absorption characteristics can be further improved by adjusting the prestress and controlling the rock loading rate.For instance,the effective energy absorption rate of the material can be rapidly increased by applying high prestress,and it can resist the influence of rock loading rate.As the prestress is increased close to the yield stress of the material and the rock loading rate is controlled below 10-2 MPa/s,the high-strength and high-toughness bolt steel can obtain the largest effective strain(>0.54)and the highest effective energy absorption density(>4.5×10^(8)J/m^(3)),which can optimize the energy absorption characteristics of high-strength and high-toughness bolt steel.The research results provide theoretical basis and technical guidance for practical application of high-strength and high-toughness steel for rock support engineering in high in-situ stress field.