|
|
|
| Mechanical behaviors of soft rocks based on the fractional thermal elastic-plastic theory#br# |
| LI Haichao1，MA Bo1，ZHANG Sheng1，2，SHENG Daichao3#br# |
| (1. School of Civil Engineering，Central South University，Changsha，Hunan 410075，China；2. National Engineering Laboratory for High Speed Railway Construction，Central South University，Changsha，Hunan 410075，China；3. School of Civil and Environmental Engineering，University of Technology Sydney，Sydney NSW 2007，Australia) |
|
|
|
Abstract Soft rocks have complex thermodynamic behaviors and their strength maybe increase or decrease with temperature. In this paper，the soft rocks were considered as heavily over-consolidated clays and their preconsolidation pressure was assumed to be the uniaxial compression strength. Based on the fractional thermal elastoplastic theory，a fractional sub-loading surface model for soft rocks considering the effects of temperature was proposed，which can decribe associated and non-associated flow rules without introducing the plastic potential. The analysis results show that the phenomena of heat-increase and heat-decrease are closely related to the angle of the plastic flow direction and the loading direction. Application of the non-associated flow rule in the undrained triaxial test results in that stress paths of soft rocks cross through the critical state line and finally reach the critical state，and the undrained shear strength of soft rocks will increase as temperature increases. On the other hand，the associated flow rule will do the opposite. In addition，the preconsolidation pressure of soft rocks will decrease as temperature increases，leading that the sub-loading surface is located outside the temperature loading surface in the p-q plane and that the overconsolidated ratio OCR is smaller than 1. Comparisons between the proposed model with test results indicate that soft rocks show the features of strain-softening and dilatancy，which can be captured by the proposed model，and that，increasing temperature will decrease the fragility of soft rocks as well as the dilatancy. Compared with the modified Cam-clay model，the proposed model introduces two extra parameters including the coefficient of linear expansion and dilative related parameter m，which have clear physical meanings and can be determined through conventional tests directly.
|
|
|
|
|
|
[1] 张 锋. 计算土力学[M]. 北京：人民交通出版社，2007：31.(ZHANG Feng. Computational soil mechanics[M]. Beijing：China Communications Press，2007：31.(in Chinese))
[2] ZHANG S，LENG W，ZHANG F，et al. A simple thermo- elastoplastic model for geomaterials[J]. International Journal of Plasticity，2012，34：93–113.
[3] NAKANO H，NISHIMURA T. Temperature-controlled triaxial compression/creep test device for thermodynamic properties of soft sedimentary rock and corresponding theoretical prediction[J]. Journal of Rock Mechanics and Geotechnical Engineering，2010，(3)：67–73.
[4] 查文华，宋新龙，武腾飞. 不同温度条件下煤系砂质泥岩力学特征试验研究[J]. 岩石力学与工程学报，2014，33(4)：809–816.(ZHA Wenhua，SONG Xinlong，WU Tengfei. Experimental study of mechanical characteristics of coal-serial sandy mudstone at different temperatures[J]. Chinese Journal of Rock Mechanics and Engineering，2014，33(4)：809–816.(in Chinese))
[5] 何满潮. 深部软岩工程的研究进展与挑战[J]. 煤炭学报，2014，39(8)：1 409–1 417.(HE Manchao. Progress and challenges of soft rock engineering in depth[J]. Journal of China Coal Society，2014，39(8)：1 409–1 417.(in Chinese))
[6] NOBLE C A. Effect of temperature on strength of soils[Ph. D. Thesie][D]. Iowa，USA：Iowa State University，1968.
[7] CEKEREVAC C，LALOUI L. Experimental study of thermal effects on the mechanical behaviour of a clay[J]. International Journal for Numerical and Analytical Methods in Geomechanics，2004，28(3)：209–228.
[8] KUNTIWATTANAKUL P. Effect of high temperature on mechanical behaviour of clays[Ph. D. Thesis][D]. Tokyo：University of Tokyo，1991.
[9] 张 升，贺佐跃，滕继东，等. 考虑结构性的软岩热弹塑性本构模型研究[J]. 岩石力学与工程学报，2017，36(3)：571–578.(ZHANG Sheng，HE Zuoyue，TENG Jidong，et al. A thermo-elasto-plastic model for soft rocks considering structure[J]. Chinese Journal of Rock Mechanics and Engineering，2017，36(3)：571–578.(in Chinese))
[10] ABUEL-NAGA H M. Thermo-mechanical behavior of soft bangkok clay：experimental results and constitutive modeling[Ph. D. Thesis][D]. Bangkok：Asian Institute of Technology，2006.
[11] GHAHREMANNEJAD B. Thermo-mechanical behaviour of two reconstituted clays[Ph. D. Thesis][D]. Sydney：The University of Sydney，2003.
[12] 李海潮，张 升，沈 远. 考虑温度影响的岩土材料高阶屈服函数[J]. 岩石力学与工程学报，2018，37(12)：2 795–2 803.(LI Haichao，ZHANG Sheng，SHEN Yuan. A high order yield function for geo-materials considering the effect of temperature[J]. Chinese Journal of Rock Mechanics and Engineering，2018，37(12)：2 795– 2 803.(in Chinese))
[13] 杨骐莱，熊勇林，张 升，等. 考虑温度影响的软岩弹塑性本构模型[J]. 岩土力学，2019，40(5)：1 898–1 906.(YANG Qilai，XIONG Yonglin，ZHANG Sheng，et al. Elastoplastic constitutive model for soft rock considering temperature effect[J]. Rock and Soil Mechanics，2019，40(5)：1 898–1 906.(in Chinese))
[14] SUN Y，GAO Y，ZHU Q. Fractional order plasticity modelling of state-dependent behaviour of granular soils without using plastic potential[J]. International Journal of Plasticity，2018，102(3)：53–69.
[15] SUN Y，XIAO Y. Fractional order plasticity model for granular soils subjected to monotonic triaxial compression[J]. International Journal of Solids and Structures，2017，118–119：224–234.
[16] CAPUTO M，M FABRIZIO. A new definition of fractional derivative without singular kernel[J]. Progress in Fractional Differentiation and Applications，2015，1(2)：73–85.
[17] 孙逸飞，沈 扬. 基于分数阶微积分的粗粒料静动力边界面本构模型[J]. 岩土力学，2018，39(4)：1 219–1 226.(SUN Yifei，SHEN Yang. Bounding surface model for granular aggregates incorporating the concept of fractional calculus[J]. Rock and Soil Mechanics，2018，39(4)：1 219–1 226.(in Chinese))
[18] 孙逸飞，高玉峰，鞠 雯. 分数阶塑性力学及其砂土本构模型[J].岩土工程学报，2018，40(8)：1 535–1 541.(SUN Yifei，GAO Yufeng，JU Wen. Fractional plasticity and its application in constitutive model for sands[J]. Chinese Journal of Geotechnical Engineering，2018，40(8)：1 535–1 541.(in Chinese))
[19] LU D，LIANG J，DU X，et al. Fractional elastoplastic constitutive model for soils based on a novel 3D fractional plastic flow rule[J]. Computers and Geotechnics，2019，105(2)：277–290.
[20] SUMELK A，WOJCIEC H. Application of fractional continuum mechanics to rate independent plasticity[J]. Acta Mechanica，2014，225(11)：3 247–3 264.
[21] SULTAN N，DELAGE P，CUI Y J. Temperature effects on the volume change behaviour of Boom clay[J]. Engineering Geology，2002，64(2)：135–145.
[22] ROSCOE K H，BURLAND J B. On the generalized stress-strain behaviour of wet clay[J]. Engineering Plasticity，1968，535–609.
[23] HASHIGUCHI K. Subloading surface model in unconventional plasticity[J]. International Journal of Solids and Structures，1989，25(8)：917–945.
[24] HASHIGUCHI K，TSUTSUMI S，OKAYASU T. Evaluation of typical conventional and unconventional plasticity models for prediction of softening behaviour of soils[J]. Géotechnique，2002，52(8)：561–578.
[25] ANANDARAJAH A，DAFALIAS Y F. Bounding surface plasticity. III：application to anisotropic cohesive soils[J]. Journal of Engineering Mechanics，1986，112(12)：1 292–1 318.
[26] YAO Y P，HOU W，ZHOU A N. UH model：Three-dimensional unified hardening model for overconsolidated clays[J]. Géotechnique，2009，59(5)：451–469.
[27] YAO Y P， ZHOU A N. Non-isothermal unified hardening model：a thermo-elasto-plastic model for clays[J]. Géotechnique，2013，63(15)：1 328–1 345.
[28] UCHAIPICHAT A，KHALILI N. Experimental investigation of thermo-hydromechanical behaviour of an unsaturated silt[J]. Géotechnique，2009，59(4)：339–53.
[29] 刘斯宏，沈超敏，毛航宇，等. 堆石料状态相关弹塑性本构模型[J]. 岩土力学，2019，40(8)：2 891–2 898.(LIU Sihong，SHEN Chaomin，MAO Hangyu，et al. State-dependent elastoplastic constitutive model for rockfill materials[J]. Rock and Soil Mechanics，2019，40(8)：2 891–2 898.(in Chinese))
[30] XIONG Y L，YE G L，ZHU H H，et al. A unified thermo- elasto-viscoplastic model for soft rock[J]. International Journal of Rock Mechanics and Mining Sciences，2017，93：1–12.
[31] 张 升，李海潮，滕继东，等. 考虑围压依存性的软岩结构性下加载面模型[J]. 岩土工程学报，2016，38(7)：1 269–1 276. (ZHANG Sheng，LI Haichao，TENG Jidong，et al. Structured subloading yield surface model for soft rock considering confining pressure[J]. Chinese Journal of Geotechnical Engineering，2016，38(7)：1 269–1 276.(in Chinese))
[32] HONG P Y，PEREIRA J M，CUI Y J，et al. A two-surface thermomechanical model for saturated clays[J]. International Journal for Numerical and Analytical Methods in Geomechanics，2016，40(7)：1 059–1 080. |
|
|
|
2020, Vol. 39 
