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| Meso-macro mechanical constitutive model under high seepage pressure in brittle rocks |
| LI Xiaozhao1，2，3，QI Chengzhi1，2，SHAO Zhushan3 |
| (1. School of Civil and Transportation Engineering，Beijing University of Civil Engineering and Architecture，Beijing 100044，China；2. Beijing Advanced Innovation Center for Future Urban Design，Beijing University of Civil Engineering and Architecture，Beijing 100044，China；3. Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering，Xi?an University of Architecture and Technology，Xi′an，Shaanxi 710055，China) |
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Abstract Meso-crack growth caused by the seepage pressure has a great significance for the macroscopic mechanical behaviors in brittle rocks. A meso-macro stress-strain constitutive model considering seepage pressure is proposed. The effects of seepage pressure on initial crack surface and wing crack surface are considered in this model. Seepage pressure weakens the normal stress on initial crack surface，and enhances the crack tension force on wing crack surface，which explains the mechanism of seepage pressure-induced crack growth. A variable of tension force at wing crack surface，i.e.，Fp，caused by seepage pressure is introduced into this proposed model，which has a key function in crack growth to failure of rocks. Combing a suggested relationship between crack growth and strain by relating meso-damage with macro-damage，the stress-strain constitutive relationship caused by microcracks growth under seepage pressure is established. Effects of seepage pressure on the stress-strain curves are studied. Rationality of the proposed model is verified by comparing the experimental data. Variations of the tension force at wing crack surface or the ratio between the tension force at wing crack surface and the tension force at initial crack surface (i.e.，Fp/Fw) with wing crack growth are analyzed. Effects of seepage pressure on crack initiation stress and peak strength are discussed.
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2020, Vol. 39 
