建立在寒区的岩土工程,其岩石的损伤劣化不仅受冻融风化作用,而且还受到开挖卸荷的影响。采用冻融循环试验和三轴卸荷试验相结合的方法,对砂岩同时受2种破坏作用的强度特性和损伤特性进行系统的分析。分析结果表明:随围压的增加,冻融循环下岩石的破坏特性由张拉破坏逐渐转变为剪切破坏特征,随着冻融次数的增加,岩样明显产生侧向膨胀,侧边中部明显向外凸出,并出现了不同级别的张裂纹、环向裂纹及许多岩粉和岩石碎块;对于三轴卸荷试验,岩样的峰值强度随着冻融次数的增加而降低;扩容应力随冻融次数增加呈指数下降关系;破坏围压与冻融次数呈二次函数关系;冻融损伤值随冻融次数增加呈线性增长,表明岩样的损伤受冻融的影响逐渐增大。研究成果可为寒区岩土工程设计和施工提供指导。
Abstract
Geotechnical projects in cold regions suffer from both cyclic freezing-thawing and excavation unloading, giving rise to rock degradation. In this article, the strength characteristics and damage characteristics of sandstone subjected to both cyclic freezing-thawing and excavation unloading are analyzed systematically by freeze-thaw cycle test and triaxial unloading test. The results are concluded as follows: in freeze-thaw cycle test, the sandstone experienced a stage from tension failure gradually to shear failure as confining pressure rises; as the freeze-thaw cycle proceeds, the sandstone witnessed an apparent lateral expansion in the middle, with different levels of tension cracks, circular cracks, rock powder and rock fragments; while in triaxial unloading test, as freezing-thawing proceeds, the peak strength of sandstone reduces, and dilatancy stress declines in an exponential relation; destructive confining pressure is in a quadratic functional relation with cycle number; moreover, the freeze-thaw damage value increases linearly with the number of freeze-thaw cycles, indicating that the effect of cyclic freezing and thawing intensifies gradually.
关键词
砂岩 /
冻融循环 /
三轴卸荷试验 /
强度特性 /
损伤特性
Key words
sandstone /
freezing and thawing cycles /
triaxial unloading test /
strength characteristics /
damage characteristics
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] 李 宁,程国栋,谢定义.西部大开发中的岩土力学问题[J].岩土工程学报,2001,23(3):268-272.
[2] CHEN T C, YEUNG M R, MORI N. Effect of Water Saturation on Deterioration of Welded Tuff due to Freeze-thaw Action[J].Cold Regions Science and Technology, 2004,38(2/3):127-136.
[3]TAKARLI M, PRINCE W, SIDDIQUE R. Damage in Granite under Heating/cooling Cycles and Water Freeze-thaw Condition[J]. International Journal of Rock Mechanics and Mining Sciences, 2008, 45(7): 1164-1175.
[4] 侯淑鹏,陈礼仪,王 胜,等.冻融循环条件下水泥土损伤劣化特征研究[J].raybet体育在线
院报, 2016,33(12): 124-127.
[5] 许 雷,鲁 洋,薛 洋,等.冻融循环下水泥改性膨胀土物理力学特性研究[J].raybet体育在线
院报, 2017,34(4):87-91.
[6] 徐光苗,刘泉声.岩石冻融破坏机制分析及冻融力学试验研究[J].岩石力学与工程学报,2005,24(17):3076-3082.
[7] 杨更社,周春华,田应国,等.软岩类材料冻融过程水热迁移的实验研究初探[J].岩石力学与工程学报,2006,25(9):1765-1770.
[8] 张慧梅,雷利娜,杨更社.温度与荷载作用下岩石损伤模型[J].岩石力学与工程学报,2014,33(增2):3391-3396.
[9] 张慧梅,杨更社.冻融荷载耦合作用下岩石损伤力学特性[J]. 工程力学,2011,28(5):161-165.
[10]陈招军,王乐华,王思敏,等.冻融循环条件下岩石加卸荷力学特性研究[J].raybet体育在线
院报,2017,34(1): 98-103.
[11]吕颖慧,刘泉声,胡云华.基于花岗岩卸荷试验的损伤变形特征及其强度准则[J].岩石力学与工程学报,2009,28(10):2096-2103.
[12]吕颖慧,刘泉声,江 浩.基于高应力下花岗岩卸荷试验的力学变形特性研究[J].岩土力学,2010,31(2):337-344.
[13]李建林,陈 星,党 莉,等.高温后砂岩三轴卸荷试验研究[J].岩石力学与工程学报,2011,30(8):1587-1595.
[14]陈国庆,李天斌,何勇华,等.深埋硬岩隧道卸荷热-力效应及岩爆趋势分析[J].岩石力学与工程学报, 2013,32(8):1554-1563.
[15]姜德义,范金洋,陈 结,等. 盐岩在围压卸荷作用下的扩容特征研究[J]. 岩土力学,2013,34(7):1881-1886.
基金
国家自然科学基金项目(41272329,51379065);国家自然科学基金青年基金项目(51409122)
PDF(3347 KB)
