动载荷作用下裂隙岩体的止裂机理分析

周磊; 姜亚成; 朱哲明; 董玉清; 牛草原; 王蒙

doi:10.11883/bzycj-2020-0125

动载荷作用下裂隙岩体的止裂机理分析

doi: 10.11883/bzycj-2020-0125

四川大学建筑与环境学院深地科学与工程教育部重点实验室，四川成都 610065

基金项目: 国家自然科学基金(U19A2098)；四川省科技计划项目(2021YJ0511)；深地科学与工程教育部重点实验室(四川大学)开放基金(DESE202005)；工程材料与结构冲击振动四川省重点实验室开放基金(18yfjk02)

详细信息

作者简介:
周　磊（1990－　），男，博士，助理研究员，zhouleittkx@126.com

通讯作者:
朱哲明（1965－　），男，博士，教授，博士生导师，zhemingzhu@hotmail.com

中图分类号: O346.1
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- 被引次数: 0
出版历程
- 收稿日期: 2020-04-30
- 修回日期: 2020-07-24
- 网络出版日期: 2021-03-05
- 刊出日期: 2021-05-05

Mechanism study of preventing crack propagation of fractured rockunder dynamic loads

MOE Key Laboratory of Deep Underground Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan, China

摘要

摘要: 为深层次了解裂隙岩体在动载荷作用下的动态断裂特性及止裂机理，采用TWSRC（tunnel with single radial crack）构型进行中低速冲击实验，选择砂岩作为原材料制作裂隙岩体试样，以落锤冲击试验装置与裂纹扩展计实验系统对裂纹的动态起裂、扩展及止裂过程进行全过程监测，重点研究动态破裂过程的破裂行为及止裂现象。使用有限差分法程序进行数值模拟，验证冲击实验结果的科学性与准确性。研究发现：裂隙岩体的动态断裂过程是由起裂加速-高速扩展-缓慢减速-止裂-再次起裂加速-再次高速扩展等多次循环的过程构成，且止裂区间尺寸为微秒量级；裂隙岩体止裂位置的穿晶断裂比例远小于初始起裂点，青砂岩动态断裂过程的穿晶断裂比例稍大于黑砂岩；裂隙岩体中止裂点再次起裂所需的能量，远小于预制裂纹初始起裂所需要的能量。
- 裂隙岩体 /
- 动载荷 /
- 裂纹扩展速度 /
- 止裂 /
- 能量演化
Abstract: To deeply understanding dynamic fracture properties and preventing crack propagation of fractured rock mass under dynamic loads, impact experiments were conducted using TWSRC (tunnel with single radial crack) samples, and sandstone were selected as the raw material to manufacture fractured rock samples. The crack initiation, propagation and obstructing behavior were measured by using a drop hammer impact test device and crack propagation gauge measuring system. The mechanism of preventing crack propagation and failure behavior during dynamic fracturing process was focused, and then the corresponding numerical simulation was conducted by using the finite difference code, which can be used to accurately estimate the experiment result. The results indicate that the whole dynamic fracturing process of fractured rock under dynamic loads is composed of the cyclic process of crack initiation, high-speed crack propagation, slowly deceleration, preventing crack propagation. In addition, the period of crack obstruction was approximate the microsecond level. The ratio of transgranular (TG) fracture at the crack obstruction point of fractured rock was smaller than that of the crack initiation point, and the ratio of TG fracture of green sandstone during the dynamic fracturing process was larger than that of black sandstone. The fracture energy for crack initiation again after crack obstruction was much less than the fracture energy required for the initial initiation of pre-existing crack.
- fractured rock mass /
- dynamic load /
- crack propagation velocity /
- crack arrest /
- energy evolution

HTML全文

图 1 TWSRC构型

Figure 1. TWSRC sample

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图 2 砂岩材料的XRD成分分析

Figure 2. XRD analyses of sandstone materials

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图 3 落锤冲击试验装置

Figure 3. Drop hammer impact device

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图 4 冲击脉冲信号

Figure 4. Impulse signals

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图 5 实验结果

Figure 5. Experimental results

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图 6 青砂岩的快速扩展

Figure 6. Rapidly propagation of green sandstone

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图 7 电镜扫描图像

Figure 7. Scanning electron micrograph

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图 8 数值模型网格

Figure 8. Mesh of numerical model

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图 9 最大主应力

Figure 9. Maximum principal stresses

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图 10 数值模拟结果

Figure 10. Numerical simulation results

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图 11 止裂点和再次起裂点的应力变化

Figure 11. Stress variations at crack arrest point and crack again point

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图 12 起裂点、止裂点和再次起裂点的能量变化

Figure 12. Energy variations at crack point, crack arrest point and crack again point

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表 1 砂岩的力学性能

Table 1. Mechanical properties of sandstone materials

材料	ρ/（kg·m⁻³）	E/GPa	μ	f_d/MPa	c_l/（m·s⁻¹）	c_t /（m·s⁻¹）
青砂岩	2 265	13.58	0.165	24.84	2 563	1 607
黑砂岩	2 650	33.67	0.205	52.96	3 678	2 239

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表 2 实验结果

Table 2. Experimental results

试件	v_s/（m·s⁻¹）	t_i/μs	t_a/μs	v_a/（m·s⁻¹）	l_a/mm
青砂岩1	8.43	342.4	97.6	368.6	15.4
青砂岩2	8.40	356.1	79.6	363.7	24.2
青砂岩3	8.38	367.4	57.2	302.7	15.4
黑砂岩1	8.47	370.8	54.2	310.1	19.8
黑砂岩2	8.41	350.0	81.7	372.9	15.4
黑砂岩3	8.39	387.0	85.9	396.1	8.8

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