Email Alerts
RSS
Experimental study of unloading impact on deformation behavior and strength of mudstone in sampling state
-
摘要: 泥岩强度和变形参数是工程设计与施工控制的重要指标。为研究卸荷作用和水岩作用对膨胀性泥岩强度和变形特性的影响程度，选取南宁盆地典型膨胀性泥岩为研究对象，进行了加卸荷剪切试验和无荷膨胀率试验，在此基础上，分析了卸荷泥岩强度变化规律，探讨了水岩作用对卸荷泥岩变形特性的影响程度。试验结果表明，卸荷作用引起泥岩强度降低，压缩性增大，相比于加载条件，卸荷状态下泥岩的黏聚力明显较高，而内摩擦角则相对较小。引入卸荷比和强度损失率分析了卸荷泥岩的强度变化规律，卸荷泥岩强度损失率随卸荷比增加而增大，当卸荷比为0.7~0.8时，泥岩强度损失率最大。相对于卸荷作用，水岩作用对泥岩变形特性的影响较大，对样品的损伤约占30%~65%。研究结果表明获取试样力学参数中不能忽略取样过程对泥岩强度和变形特性的影响。Abstract: The strength and deformation characteristics of mudstone are important reference indexes in the engineering design and construction management. In order to analyse the effect of water-rock interaction and unloading on the strength properties and deformation characteristics of expansive mudstone, the sample of typical expansive mudstone in Nanning basin is chosen for the loading and unloading shear test and unloaded expansion ratio test. The intensity change rule of unloading mudstone is analyzed. And the influence of water-rock interaction on the deformation characteristics is discussed. The deformation and the curve of unloaded expansion ratio test are obtained. The experimental results show that sampling unloading has a great influence on the strength and compressibility, as well as the expansion deformation. Due to the unloading, the strength of mudstone decreases and the compression ratio of mudstone increases. The internal friction angle under unloading condition is smaller than that under the loading condition, while the value of cohesion increases. The unloading ratio and the loss strength rate are used to analyze the variation law of the strength of unloading mudstone. With the increase of the unloading ratio, the loss strength rate of unloading mudstone also increases. When the unloading ratio is between 0.7 and 0.8, the loss rate of mudstone strength is the largest. Compared with the unloading effect, the water-rock interaction has a greater influence on the deformation characteristics of unloading mudstone, and its structural damage to mudstone is up to 30% ~ 65% during the sampling progress. So, the influence of sampling process on the strength and deformation characteristics of mudstone can't be ignored.
-
Key words:
- mudstone /
- sampling unloading /
- stress path /
- strength /
- deformation
-
图 4 超固结土固结不排水剪试验中的应力路径
Figure 4. Stress parth for a consolidated-undrained triaxial test on overconsolidated soil
图 6 加、卸状态下泥岩强度关系曲线
Figure 6. Intensity curve of mudstone under conditions of loading and unloading respectively
图 9 水岩作用下膨胀率与时间的关系曲线
Figure 9. Relationship between swelling rate and time under water-rock interaction
表 1 卸载试验情况
Table 1. Test conditions of unloading
荷载作用方式 样号(个数) 竖向荷载 固结稳定标准与卸荷稳定标准 P1/kPa P2/kPa 卸载作用 XZ-1(2) 100 100→25 固结和卸荷稳定标准为每级荷载作用下，每小时变形低于0.01 mm，且连续出现2次以上，即可进行下一步试验 XZ-2(4) 200 200→25 XZ-3(6) 300 300→25 XZ-4(8) 400 400→25 注：P1为固结压力，P2为剪切时作用在试件上的法向压力。“→”表示卸载过程，每级卸荷量为50 kPa，最后一级压力为25 kPa。 
下载: 导出CSV
表 2 泥岩物理性质指标
Table 2. Physical and mechanical parameters of mudstone
天然含水量ω/% 重度γ/(kN·m-3) 孔隙比e 饱和度Sr/% 液限ωL/% 塑限ωP/% 液性指数IL 塑性指数IP 19.6 21.1 0.565 93.0 41.9 20.3 -0.05 21.6
下载: 导出CSV
表 3 卸载试样抗剪强度指标
Table 3. Shear strength index of unloading samples
固结压力P1/kPa 黏聚力c/ kPa 内摩擦角φ/° 100 275.6 28.9 200 299.3 26.9 300 331.7 30.6 400 363.1 29.4
下载: 导出CSV
表 4 固结与卸荷作用下的变形量
Table 4. Deformation under consolidation and unloading
样号 固结压力
P0/kPa固结变形量/mm 卸荷稳定变形量/mm 回弹量/
mm1 100 1.03 0.87 0.16 2 200 1.25 0.64 0.61 3 300 1.75 1.26 0.49 4 400 1.65 0.77 0.88
下载: 导出CSV
表 5 取样卸荷作用模拟试验的泥岩变形情况
Table 5. Deformation of mudstone under unloading
样号 损伤样品膨胀变形量/mm 非损伤样品膨胀变形量/mm 卸荷回弹变形量/mm 非损伤样品总变形量/mm 水岩作用损伤度/% 卸荷作用损伤度/% 1 1.93 3.56 0.16 3.72 51.88 4.30 2 2.63 3.93 0.61 4.54 57.93 13.40 3 2.10 2.72 0.49 3.21 65.42 15.26 4 1.27 3.32 0.88 4.20 30.24 20.95
下载: 导出CSV
表 6 无荷膨胀率试验指标
Table 6. Physical parameters of unloaded swelling ratio test
样号 原状样品物理指标 原状样品无荷膨胀率试验指标 卸荷样品无荷膨胀率试验指标 含水量/
%密度/
(g·cm-3)孔隙比 含水量/
%密度/
(g·cm-3)孔隙比 无荷膨胀率/% 含水量/
%密度/
(g·cm-3)孔隙比 无荷膨胀率/% 1 27.16 2.10(1.65) 0.666 36.12 2.23(1.64) 0.682 9.65 36.63 2.18(1.60) 0.723 18.63 2 22.96 2.11(1.71) 0.588 33.30 2.27(1.70) 0.600 13.16 36.24 2.24(1.65) 0.654 20.62 3 24.26 2.11(1.70) 0.622 30.69 2.15(1.63) 0.687 9.52 31.04 2.19(1.65) 0.671 14.15 4 21.84 2.11(1.73) 0.588 27.26 2.23(1.75) 0.570 6.33 29.29 2.21(1.71) 0.612 16.75 注：()中值为相应干密度。
下载: 导出CSV
-
[1] 马福荣, 李芒原, 陈青生, 等.南宁盆地第三系泥岩参数试验方法改进[J].广西大学学报(自然科学版), 2008, 33(2): 128-132. http://d.wanfangdata.com.cn/Periodical/gxdxxb200802008 MA Furong, LI Mangyuan, CHEN Qingsheng, et al. Improvement on testing method for parameters of the mudstone of tertiary in Nanning basin[J]. Journal of Guangxi University(Natural Science Edition), 2008, 33(2): 128-132.(in Chinese) http://d.wanfangdata.com.cn/Periodical/gxdxxb200802008 [2] CARRUBBA P. Stress relief disturbance and residual pore pressure in cohesive soils[J]. Soils and Foundations, 2000, 40(1): 57-72. doi: 10.3208/sandf.40.57 [3] WATABE Y, TSUCHIDA T. Influence of stress release on sample quality of pleistocene clay collected from large depthin Osaka bay[J]. Soils and Foundations, 2001, 41(4): 17-24. doi: 10.3208/sandf.41.4_17 [4] 王璐, 刘建锋, 杨昊天, 等.深埋大理岩卸荷力学特性的试验研究[J].四川大学学报(工程科学版), 2014, 46(2): 46-51. http://d.wanfangdata.com.cn/Periodical/scdxxb-gckx201402007 WANG Lu, LIU Jianfeng, YANG Haotian, et al. Experimental research on mechanical properties of deeply buried marble under unloading conditions[J]. Journal of Sichuan University (Engineering Science Edition), 2014, 46(2): 46-51.(in Chinese) http://d.wanfangdata.com.cn/Periodical/scdxxb-gckx201402007 [5] 张凯, 周辉, 潘鹏志, 等.不同卸荷速率下岩石强度特性研究[J].岩土力学, 2010, 31(7): 2072-2078. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=ytlx201007010&dbname=CJFD&dbcode=CJFQ ZHANG Kai, ZHOU Hui, PAN Pengzhi, et al. Characteristics of strength of rocks under different unloading rates[J]. Rock and Soil Mechanics, 2010, 31(7): 2072-2078.(in Chinese) http://kns.cnki.net/KCMS/detail/detail.aspx?filename=ytlx201007010&dbname=CJFD&dbcode=CJFQ [6] 张成良, 杨绪祥, 余贤斌.加卸荷条件下辉绿岩岩体力学参数特性研究[J].地下空间与工程学报, 2012, 8(2): 280-285. http://d.wanfangdata.com.cn/Periodical/dxkj201202010 ZHANG Chengliang, YANG Xuxiang, YU Xianbin. Experimental study of diabase mechanical properties by tri-axial loading and unloading tests[J]. Chinese Journal of Underground Space and Engineering, 2012, 8(2): 280-285.(in Chinese) http://d.wanfangdata.com.cn/Periodical/dxkj201202010 [7] 严鹏, 卢文波, 陈明, 等.高应力取芯卸荷损伤及其对岩石强度的影响[J].岩石力学与工程学报, 2013, 32(4): 681-688. http://d.wanfangdata.com.cn/Periodical/yslxygcxb201304005 YAN Peng, LU Wenbo, CHEN Ming, et al. Coring-induced unloading damage to rock samples under high stress condition and its impact on rock strength[J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(4): 681-688.(in Chinese) http://d.wanfangdata.com.cn/Periodical/yslxygcxb201304005 [8] 赵国彦, 戴兵, 董陇军, 等.不同应力路径下岩石三轴卸荷力学特性与强度准则研究[J].岩土力学, 2015, 36(11): 3121-3128. http://d.wanfangdata.com.cn/Periodical/ytlx201511011 ZHAO Guoyan, DAI Bing, DONG Longjun, et al. Experimental research on mechanical characteristics and strength criterion of rock of triaxial unloading tests under different stress paths[J]. Rock and Soil Mechanics, 2015, 36(11): 3121-3128.(in Chinese) http://d.wanfangdata.com.cn/Periodical/ytlx201511011 [9] 张楚旋, 戴兵, 吴秋红.不同应力路径下岩石卸荷破坏过程的变形特性与能量耗散分析[J].中国安全生产科学技术, 2014, 10(10): 35-40. http://d.wanfangdata.com.cn/Periodical/zgzyaqwsgltxrz201410007 ZHANG Chuxuan, DAI Bin, WU Qiuhong. Analysis on deformation properties and energy dissipation of rock unloading failure process under different stress path[J]. Journal of Safety Science and Technology, 2014, 10(10): 35-40.(in Chinese) http://d.wanfangdata.com.cn/Periodical/zgzyaqwsgltxrz201410007 [10] 黄伟, 沈明荣, 张清照.高围压下岩石卸荷的扩容性质及其本构模型研究[J].岩石力学与工程学报, 2010, 29(增刊2): 3475-3481. http://d.wanfangdata.com.cn/Periodical/yslxygcxb2010z2005 HUANG Wei, SHEN Mingrong, ZHANG Qingzhao. Study of unloading dilatancy property of rock and its constitutive model under high confining pressure[J]. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(Suppl2): 3475-3481.(in Chinese) http://d.wanfangdata.com.cn/Periodical/yslxygcxb2010z2005 [11] 郭印同, 杨春和, 付建军.盐岩三轴卸荷力学特性试验研究[J].岩土力学, 2012, 33(3): 725-731. http://d.wanfangdata.com.cn/Periodical/ytlx201203012 GUO Yintong, YANG Chunhe, FU Jianjun. Experimental research on mechanical characteristics of salt rock under triaxial unloading test[J]. Rock and Soil Mechanics, 2012, 33(3): 725-731.(in Chinese) http://d.wanfangdata.com.cn/Periodical/ytlx201203012 [12] 李栋伟, 汪仁和, 范菊红.基于卸荷试验路径的泥岩变形特征及数值计算[J].煤炭学报, 2010, 35(3): 387-391. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=mtxb201003011&dbname=CJFD&dbcode=CJFQ LI Dongwei, WANG Renhe, FAN Juhong. The deformation properties of mudstone and numerical calculation based on unloading path[J]. Journal of China Coal Society, 2010, 35(3): 387-391.(in Chinese) http://kns.cnki.net/KCMS/detail/detail.aspx?filename=mtxb201003011&dbname=CJFD&dbcode=CJFQ [13] 原先凡, 邓华锋, 李建林.砂质泥岩卸荷流变本构模型研究[J].岩土工程学报, 2015, 37(9): 1733-1739. doi: 10.11779/CJGE201509024 YUAN Xianfan, DENG Huafeng, LI Jianlin. Unloading rheological constitutive model for sandy mudstone[J]. Chinese Journal of Geotechnical Engineering, 2015, 37(9): 1733-1739.(in Chinese) doi: 10.11779/CJGE201509024 [14] 王宇, 李建林, 邓华锋, 等.软岩三轴卸荷流变力学特性及本构模型研究[J].岩土力学, 2012, 33(11): 3338-3345. http://d.wanfangdata.com.cn/Conference/7895656 WANG Yu, LI Jianlin, DENG Huafeng, et al. Investigation on unloading triaxial rheological mechanical properties of soft rock and its constitutive model[J]. Rock and Soil Mechanics, 2012, 33(11): 3338-3345.(in Chinese) http://d.wanfangdata.com.cn/Conference/7895656 [15] 邓华锋, 原先凡, 李建林, 等.软岩三轴加-卸载试验的破坏特征及抗压强度取值方法研究[J].岩土力学, 2014, 35(4): 959-966. http://d.wanfangdata.com.cn/Periodical/ytlx201404007 DENG Huafeng, YUAN Xianfan, LI Jianlin, et al. Research on failure characteristics and determination method for compressive strength of soft rock in triaxial loading and unloading tests[J]. Rock and Soil Mechanics, 2014, 35(4): 959-966.(in Chinese) http://d.wanfangdata.com.cn/Periodical/ytlx201404007 [16] 张信贵, 易念平, 黄绍铿.南宁盆地泥岩承载性状研究[J].岩石力学与工程学报, 2000, 19(3): 357-360. http://d.wanfangdata.com.cn/Periodical/yslxygcxb200003022 ZHANG Xingui, YI Nianping, HUANG Shaokeng. Research on the bearing properties of mudstone in Nanning basin[J]. Chinese Journal of Rock Mechanics and Engineering, 2000, 19(3): 357-360.(in Chinese) http://d.wanfangdata.com.cn/Periodical/yslxygcxb200003022 -
点击查看大图
图(9) / 表 (6)
计量
- 文章访问数: 936
- HTML全文浏览量: 26
- PDF下载量: 303
- 被引次数: 0
