不同粗糙度岩体节理面的应力松弛特性及机理

王振; 顾琳琳; 沈明荣

doi:10.3969/j.issn.0258-2724.20190395

不同粗糙度岩体节理面的应力松弛特性及机理

doi: 10.3969/j.issn.0258-2724.20190395

王振^1,2,,
顾琳琳^3, ,,
沈明荣⁴

基金项目: 国家自然科学基金（51908288）

详细信息

作者简介:
王振（1987—），男，讲师，博士，研究方向为岩体力学及地下工程，E-mail：wangzhen2012@njust.edu.cn

通讯作者:
顾琳琳（1987—），女，讲师，博士，研究方向为岩土力学，E-mail：linlin_gu@njust.edu.cn

中图分类号: TU 448.27
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- 被引次数: 0
出版历程
- 收稿日期: 2019-05-06
- 修回日期: 2019-10-02
- 网络出版日期: 2019-12-11
- 刊出日期: 2021-04-15

Stress Relaxation Behavior and Mechanism of Rock Joint Planes with Different Roughness

WANG Zhen^{1,2
,},
GU Linlin^{3
, ,},
SHEN Mingrong⁴

摘要

摘要: 应力松弛是岩体节理面时效特性的重要组成部分，也是影响岩体工程长期稳定性的重要因素. 为研究不同粗糙度岩体节理面的应力松弛特性，并进一步探索节理面的应力松弛机理，选取Barton标准剖面为人工模拟节理面的表面形态，并用水泥砂浆浇筑成型；然后，对其进行了分级加载剪切应力松弛试验，研究了不同粗糙度节理面在不同初始应力水平下的应力松弛曲线及应力松弛速率曲线特征，给出了松弛应力与初始应力之间的关系，并结合试验现象分析了应力松弛的发生机理. 研究成果表明：随着初始松弛应力的升高，松弛应力先减小后增大，即岩体节理面应力松弛能力先减弱后增大，该现象与剪切过程中节理面的变形和裂隙发展有关，应力松弛是试验机为保持变形不变而不断调整，同时内部裂隙发育导致其内部抗力减小，进而引起应力下降的过程，并且粗糙度（JRC）越大，应力松弛能力越强.
- 应力松弛 /
- 分级加载松弛试验 /
- 节理面 /
- 松弛机理
Abstract: Stress relaxation is an important part of time-dependent behavior of rock joints, and also an important factor affecting the long-term stability of engineering rock masses. To study the stress relaxation characteristics of rock joints with different roughness and further explore the stress relaxation mechanism of rock joint planes, samples with artificial joint surfaces based on Barton’s standard profile lines were prepared by pouring cement mortar into shape. Then, shear stress relaxation tests with a multi-stage loading process were conducted to investigate characteristics of stress relaxation curves and stress relaxation rate curves for joint surfaces with different joint roughness coefficient (JRC) under different initial stress levels, the relationships between initial stress and relaxation stress were obtained, and the mechanism of stress relaxation was analyzed from the test phenomena. The results show that with the increase of the initial stress, the relaxation stress decreases first and then increases; that is, the stress relaxation ability of the rock joint planes decreases first and then increases. This phenomenon is related to the deformation and crack development of joint planes during the shear tests. The stress relaxation is a process in which the test machine constantly adjusts to keep the deformation unchanged and the development of internal cracks leads to the reduction of internal resistance, further resulting in the decrease of shear stress; moreover, the stress relaxation ability of the rock joint planes increases with the increasing of JRC.
- stress relaxation /
- stress relaxation test with muti-stage loading /
- rock joint /
- stress relaxation mechanism

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图 1 岩石双轴流变试验机

Figure 1. Biaxial rheological test machine

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图 2 试样制作过程

Figure 2. Sample preparation process

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图 3 试验中的采用巴顿曲线剖面及试验样品

Figure 3. Barton’s standard profile lines and sample for test

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图 4 分级松弛试验加载过程示意

Figure 4. Schematic diagram of loading process in the multi-stage stress relaxation test

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图 5 分级加载剪切应力松弛试验全过程曲线

Figure 5. Complete curves of multi-stage loading relaxation tests

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图 6 总松弛应力与初始应力之间的关系

Figure 6. Relationships between total relaxation stress and initial stress

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图 7 松弛应力/初始应力与初始应力/峰值应力的关系

Figure 7. Relationships between the relaxation stress to initial stress ratio and the initial stress to peak stress ratio

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图 8 分级加载剪切应力松弛曲线

Figure 8. Shear stress relaxation curves with multi-stage loading

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图 9 分级加载剪切应力松弛速率曲线

Figure 9. Shear stress relaxation rate curves with multi-stage loading

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图 10 初始松弛速率与应力比的关系

Figure 10. Relationships between initial stress relaxation rates and stress ratio

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图 11 应力松弛过程中的试验机响应

Figure 11. Response of test machine during stress relaxation

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表 1 不同粗糙度节理面的剪切强度

Table 1. Shear strength of joints with different JRCs

JRC	剪切强度/MPa
1	4.90
7	5.77
19	7.20
完整	8.55

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表 2 分级加载剪切应力松弛试验应力表

Table 2. Shear stresses of multi-stage relaxation tests

JRC	试验编号	初始应力 τ_i/MPa	破坏应力/MPa	松弛时间/h
1	1	2.35、2.82、3.29、 3.76、4.23、4.70	4.90	432
7	4	2.90、3.48、4.06、 4.64、5.22	5.77	360
19	10	3.50、4.20、4.90、 5.60、6.30、7.00	7.20	432
完整	w	4.75、5.70、6.65、 7.60、8.55	8.90	360

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