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论文中文题名:

 玄武岩单侧受微波照射下的损伤研究    

姓名:

 杨清清    

学号:

 21204228059    

保密级别:

 公开    

论文语种:

 chi    

学科代码:

 085900    

学科名称:

 工学 - 工程 - 土木水利    

学生类型:

 硕士    

学位级别:

 工程硕士    

学位年度:

 2024    

培养单位:

 西安科技大学    

院系:

 建筑与土木工程学院    

专业:

 土木水利    

研究方向:

 岩土力学与工程应用    

第一导师姓名:

 戴俊    

第一导师单位:

 西安科技大学    

论文提交日期:

 2024-06-12    

论文答辩日期:

 2024-05-30    

论文外文题名:

 Study on Damage to Basalt under Microwave Irradiation on One Side    

论文中文关键词:

 微波照射 ; 玄武岩 ; 损伤变量 ; 力学特性 ; SHPB    

论文外文关键词:

 Microwave irradiation ; Basalt ; Damage variable ; Mechanical property ; SHPB    

论文中文摘要:

在地下岩体开挖中,岩石破碎不再是只要求破碎效果和质量安全,还需要提高破岩效率,微波辅助机械破岩就是当下最受关注的新型破岩技术之一。目前在微波辅助机械破岩的试验研究中,多是直接将试样置于微波腔体进行照射,与实际隧道开挖时微波只能从掌子面照射进岩石内部的情况不相符,因此,需要开展岩石单侧受微波照射的室内试验。本文首先总结了微波破岩的基本理论并采用铜箔包裹法开展微波照射岩石单侧试验,验证了该方法的可行性;其次研究了不同微波照射参数照射后的玄武岩表面升温特性、纵波波速、损伤变量等变化规律;接着通过单轴压缩试验及动态冲击试验分析了不同微波照射参数对岩石应力-应变曲线、力学性能及破碎形态的影响规律。论文的主要研究内容及结论如下:

(1)同一照射功率下,玄武岩上表面升温速率随照射时间增加逐渐降低。侧面温度由上至下表现为先迅速上升,后逐渐降低,最后趋于平缓,最大值在距离顶部0~20 mm范围内,且照射时间越长侧面温度最大值的距离越靠下。

(2)随着功率和时间的增加,岩石照射前后纵波波速差逐渐增大。波速差与照射时间、微波功率呈现二次多项式变化趋势。不同照射时间下,试样平均质量损失率随功率增大逐渐由非线性向线性变化。

(3)随着微波功率和照射时间的增加,玄武岩单轴压缩应力-应变曲线表现出明显变化:压密段延长、弹性段斜率减小、屈服段显著增加,岩石表现出脆转塑性的趋势;低功率微波照射对岩石强度影响较小。纵波波速是最直观反映微波造成岩石损伤程度的指标,大功率、长时间照射下,采用纵波波速和峰值应力定义的损伤变量二者差异越小。

(4)单轴压缩过程中系统能量演化主要包含四个阶段:裂纹闭合压密阶段、线弹性变形阶段、裂纹发展阶段以及峰后破坏阶段。岩石破碎形态随微波照射时间、功率的增加由能看出原始形态、保持较高完整度到破碎成多块岩石碎块,碎块形状由长条形过渡为块状,进一步说明功率和照射时间的增加使得岩石损伤逐渐加剧。

(5)玄武岩动态冲击应力-应变曲线形貌随微波功率、照射时间的增大,逐渐由“高瘦”趋于“矮胖”。当微波能量相同时,增加功率会导致岩石强度更快削弱;动态峰值应变随着照射时间和功率的增加而增加。微波功率和照射时间增加时,岩石破碎尺度减小,碎块数量增加,裂纹数量也会有所不同。就破坏模式而言,主要包括轴向劈裂破坏和沿轴向及垂直于轴向的破坏。

论文外文摘要:

In the excavation of underground rock mass, rock fragmentation is no longer only required for fragmentation effect and quality safety, but also to improve the efficiency of rock fragmentation. Microwave assisted mechanical rock fragmentation is currently one of the most concerned new rock fragmentation technologies. At present, in the experimental research of microwave-assisted mechanical rock breaking, the samples are mostly directly placed in the microwave chamber for irradiation, which is inconsistent with the situation where microwaves can only be irradiated into the interior of the rock from the palm face during actual tunnel excavation. Therefore, it is necessary to carry out indoor experiments on one side of the rock under microwave irradiation. This article first summarizes the basic theory of microwave rock breaking and uses the copper foil wrapping method to conduct single-sided experiments on microwave irradiated rocks, verifying the feasibility of this method; Secondly, the temperature rise characteristics, longitudinal wave velocity, and damage variables of basalt surface after different microwave irradiation parameters were studied; Subsequently, the influence of different microwave irradiation parameters on the stress-strain curve, mechanical properties, and fracture morphology of rocks was analyzed through uniaxial compression tests and dynamic impact tests. The main research content and conclusions of the paper are as follows:

 (1) Under the same irradiation power, the heating rate of the upper surface of basalt gradually decreases with the increase of irradiation time. From top to bottom, the side temperature rises rapidly at first, then gradually decreases, and finally tends to be gentle. The maximum value is within the range of 0~20 mm from the top, and the longer the irradiation time, the lower the distance of the maximum value of the side temperature.

(2) As power and time increase, the difference in longitudinal wave velocity before and after rock irradiation gradually increases. The trend in wave velocity difference with respect to irradiation time and microwave power follows a quadratic polynomial. Under different irradiation times, the average mass loss rate of the sample gradually changes from nonlinear to linear with increasing power.

(3) With the increase of microwave power and irradiation time, the compaction section of the uniaxial compressive stress-strain curve of the sample becomes longer, the slope of the elastic section decreases, and the yield section gradually becomes significant. Low power microwave irradiation has little effect on rock strength. The longitudinal wave velocity is the most direct indicator to reflect the damage degree caused by microwave. Under high power and long time irradiation, the difference between the damage variables defined by longitudinal wave velocity and peak stress is smaller.

(4) The system energy evolution in the uniaxial compression process mainly includes four stages: crack closure compaction stage, linear elastic deformation stage, crack development stage and post-peak failure stage. With the increase of microwave irradiation time and power, the rock broken form changes from being able to see the original form and maintain a high degree of integrity to being broken into several rock fragments, and the fragment shape changes from strip to block, which further indicates that the increase of power and irradiation time leads to the gradual aggravation of rock damage.

(5) The morphology of the dynamic impact stress-strain curve for basalt gradually evolves from "tall and thin" to "short and plump" with the increase of microwave power and irradiation time. When the microwave energy is the same, the power is larger and the rock strength is reduced more. The dynamic peak strain is positively correlated with irradiation time and power. With the increase of microwave power and irradiation time, the fragmentation scale of rock decreases step by step, the number of fragments increases gradually, and the number of cracks is also different. As far as failure modes are concerned, they mainly include axial splitting failure and axial and vertical failure.

中图分类号:

 TU458    

开放日期:

 2024-06-13    

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