An elasto-visco-plastic model based on stress functions for deformation and damage of water-saturated rocks during the freeze-thaw process

Zhang, Chunyang; Ping-hua, Zou; Wang, Yixian; Jiang, Tianxing; Lin, Hang; Cao, Ping

doi:10.1016/j.conbuildmat.2020.118862

Cited by 67 publications

(22 citation statements)

References 64 publications

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“…To estimate the ultimate bearing capacity [34][35][36][37], maximum deflection, and flexural strength of damaged shield tunnel segment strengthening with CFRP, the tangential stress of the strengthening shield segments was analyzed as shown in Figure 16 [38][39][40]. The maximum and minimum values of the tangential stress can be calculated using the equations in Appendix B [41,42].…”

Section: Derivation Of Ultimate Bearing Capacity Formulationmentioning

confidence: 99%

Ultimate Bearing Capacity Analysis of CFRP-Strengthened Shield Segments Using Bonding Slip Behavior Experiments

Nie

2020

Materials

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Shield segments of subway tunnels are often exposed to the combined actions of several hygrothermal factors that could lead to accidents such as water seepage and tunnel collapse. Further, they often break and deform owing to formation pressure. In addition, uncertainties related to the stress relaxation characteristics and bonding performance of carbon-fiber-reinforced plastics (CFRPs) under a hygrothermal environment make their application in subway systems difficult. This study analyzes the effects of the slip-on-bending strength of CFRP-strengthened shield segments in a hygrothermal environment. In the study, the shield segments are damaged at ambient pressure under a combination of humidity (0%, 5%, and 10%) and temperature (20 °C, 25 °C, 30 °C, and 40 °C). An experimental procedure is designed to evaluate a CFRP-reinforced concrete arch. The method predicts the load–slip relationship and maximum shearing stress and strain. Moreover, confined compression tests are conducted on a tunnel segment lining strengthened with CFRP to evaluate the bearing capacity of the CFRP-strengthened shield segments. An equation for the latter’s ultimate bearing capacity is developed based on the elastic layer system theory, stress boundary condition, and bending stress characteristics of axisymmetric elements. It was found that the results from the developed model are compared with the experimental values of CFRP-strengthened shield segments under different humidity values (0%, 5%, and 10%) and a constant temperature. The ultimate strength—the debonding deflection of the CFRP-strengthened shield segment—can be predicted using the proposed ultimate bearing capacity equation with sufficient accuracy.

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Section: Derivation Of Ultimate Bearing Capacity Formulationmentioning

confidence: 99%

Ultimate Bearing Capacity Analysis of CFRP-Strengthened Shield Segments Using Bonding Slip Behavior Experiments

Nie

2020

Materials

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“…The main changes of the specimen surface after saturation in a hydrochemical solution are reflected in macro and micro aspects [8,[49][50][51].…”

Section: Rock Surface Characteristics After Acidificationmentioning

confidence: 99%

Aging Features and Strength Model of Diorite’s Damage Considering Acidization

et al. 2020

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Acidic fluids will cause rock erosion and further endanger the safety of rock engineering. To explore the aging characteristics of the mechanical damage under acid condition, diorite specimens were saturated in neutral water and acid solutions with pH values of 3 and 5 for 49 days. The masses and sizes of the specimens and the pH values of the acidic solution were tracked and measured. Besides, the specimens before and after saturations were observed by an electron microscope scanner. Meanwhile, triaxial compression tests were carried out under neutral water, pH 5 and pH 3 hydrochloric acid solutions, respectively. The mass damage features and mechanical properties of diorite specimens saturated in solutions with different pH values were analyzed. The results show: 1) after acidic saturation, the original lamellar structures and crystal forms were spongy or flocculent. The structure loosened and the boundary between layers became fuzzy. Meanwhile, the number of micro-cracks and micro-pores increased, which weakened the macro-mechanical performances of diorite; 2) the acid condition with pH value of 3 could be used to simulate the long-term effect of the weakly acidic environment in nature; 3) internal friction angle of diorite was more sensitive to acidic solutions than its cohesion; 4) at the initial stage of saturation, diorite broke rapidly. With increasing saturation time, the damage rate slowed down and finally stabilized. The established damage strength model considering acidification could properly describe the test results.

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“…Saeb and Amadei [7] extended Goodman [8] model to describe the whole shear deformation process of rock joints and a piecewise linear function was used to characterize the pre-peak and post-peak shear stress-displacement relationship. These existing theoretical explorations are conducive to a deeper understanding of the inherent laws of the research objects [9].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear shear constitutive model for peak shear-type joints based on improved Harris damage function

Xie

Lin

Wang

et al. 2020

Archiv.Civ.Mech.Eng

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The majority of jointed rock mass failures mainly occur along the joints in shear mode, which promotes a wide investigation on the proposal of a reasonable and reliable shear constitutive model of rock joints. In this paper, based on Improved Harris function and laboratory shear tests, a new constitutive model of saw-tooth joints was proposed. Firstly, a series of laboratory direct shear tests were carried out on saw-tooth joint specimens made of rock-like materials (cement mortar) to obtain the shear stress-displacement curves. Subsequently, the test results were divided into sliding failure type and peak shear type according to whether there is a significant stress drop between peak stress and residual stress. It is assumed that rock elements can be divided into undamaged parts and damaged parts during the shearing process. The stress-displacement relation of the undamaged part satisfies Hooke's law, while the damaged part provides residual stress. Via the comparison with commonly used micro-element failure probability density functions, the Improved Harris distribution function was selected as the standard to characterize the strength of micro rock units. Finally, derived from the theory of damage statistical mechanics, a damage statistical constitutive model was proposed, which can reflect the deformation characteristics of rock joints. Compared with previous models and experimental data, the model proposed in this paper can represent the trend of peak shear curve variation with higher accuracy, the parameters are easy to be solved and have obvious physical significance, which verifies the advantages and applicability of this model.

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An elasto-visco-plastic model based on stress functions for deformation and damage of water-saturated rocks during the freeze-thaw process

Cited by 67 publications

References 64 publications

Ultimate Bearing Capacity Analysis of CFRP-Strengthened Shield Segments Using Bonding Slip Behavior Experiments

Ultimate Bearing Capacity Analysis of CFRP-Strengthened Shield Segments Using Bonding Slip Behavior Experiments

Aging Features and Strength Model of Diorite’s Damage Considering Acidization

Nonlinear shear constitutive model for peak shear-type joints based on improved Harris damage function

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