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Study on Water-Rock Interaction with the Cyclic Drying-Wetting Effect on Rock

Author: FuZuo
Tutor: LiuXinRong;ZhangYongXing
School: Chongqing University
Course: Geotechnical Engineering
Keywords: cyclic drying-wetting effect statistical rock damage PFC mechanism of deterioration stability of reservoir bank
CLC: TU452
Type: PhD thesis
Year: 2010
Downloads: 361
Quote: 1
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Abstract

As the advancing edge of geotechnical engineering and its related science studies, water-rock interaction is a crucial content of the study of the stability of engineering rock-mass and soil. And in the procedure of cyclic drying-wetting, which is one of water-rock interaction’s important compositions, rock-mass altered the current state of water, while suffering repeated erosion itself, which would result in the deterioration of rock and soil, influence its the strength and deformation parameters, and leave significant effect on the stability and durability of geotechnical engineering. Based on previous studies and from the prospect of deterioration procedure of effect of cyclic drying-wetting, this thesis is about to proceed a systematic and deep study on the deterioration mechanism of rock-mass under cyclic drying-wetting effect with research methods like theoretical analysis, laboratory test, and numerical simulation. Major contents and results are as the following:①Rules caused by effect of cyclic drying-wetting are discovered with the laboratory test of cyclic drying-wetting effect on integrated sandstone. It is a gradual process as suggested in the experiment results, in whose primary stage the influence is the greatest, and deterioration effect fades as time passes by. Therefore, the function relationship between the rock mechanics parameters and cycles of drying and wetting are discussed, and degradation coefficient of cyclic drying-wetting is furthermore defined to signify the degree of influence of cyclic drying-wetting effect on each parameter.②On the basis of experimental study, continuum damage mechanics and statistical theory are applied in the introduction of the statistical damage constitutive model of rock-mass under the effect of cyclic drying-wetting. The model is testified with the sandstone experiment results, and the analysis indicates that the effect of cyclic drying-wetting on the sandstone’s stress-strain curves can be categorized into two sorts: the approximate linear part is influenced by the variation of young’s modulus E, while the nonlinear part the Weibull distribution parameters m and F0. The increase in number of drying-wetting cycles would decrease the distribution parameters m and F0 and critical-damage effective stressσ1c*, and increase critical damage value Dc.③With the laboratory test and microscopic particle flow numerical experiments, the basic relationship between the rock’s macroscopic and microscopic parameters is concluded, and the influence effect of macroscopic and microscopic parameters is analyzed, hence the quantitative expressions of the relation between macroscopic and microscopic parameters. Then, half-quantitative confirming method of rock’s macroscopic and microscopic parameters is established based on particle flow theory. The analysis of the particle flow calculation results show that contact network of the grains under the same confining pressure under peak stress own the similar distribution form. The number of cracks under peak stress is increased with cycles of drying and wetting. The energy of equivalent micro-beam is used to educe the quantitative relation between micro-strength parameters and fracture toughness, which explains the physical significance of the micro-strength parameters of rock.④Rules of density of strain energy and micro-strength parameters of the sandstones are discussed and micro-degradation coefficient of cyclic drying-wetting is defined to signify the degree of influence of cyclic drying-wetting effect on each micro-parameters. Micro-damage constitutive model of sandstone is established with the analysis of contact normal and shear modulus, and micro-damage effect of cyclic drying-wetting is probed into.⑤Quantitative relation between integrity coefficient of jointed rock mass and GSI system is established on basis of previous study, and so is volumetric joint count. Then, GSI classification is amended. Parameters of rock mass are deduced based on generalized Hoek-Brown criterion. And the effect of cyclic drying-wetting on rock mass is discussed. The concept of shear strength reduction is applied to deduce the improvement of strength reduction method based on Hoek-Brown criterion, and it is programmed with FISH language. Numerical simulation of both the normal and limit conditions of reservoir bank mode4l via FLAC2D is proceeded, and the stability of reservoir bank caused by degradation of rock mass with the effect of cyclic drying-wetting is discussed.

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