https://www.jstage.jst.go.jp/article/sandf/50/1/50_1_45/_pdf

Stress-strain relationships and nonlinear mohr strength criteria of frozen sandy clay

A series of triaxial compression tests were carried out on frozen sand clay with confining pressures from 0.0 to 18.0 MPa at -6 ℃. The experimental results indicate that the strain softening exists in the stress-strain relationships of the studied frozen sand clay when the confining pressures is below 3.0 MPa;and the strain hardening phenomenon appears in the stress-strain relationships when confining pressures is greater than 3.0 MPa. Since the general hyperbolic model cannot describe the strain hardening behavior;and Duncan-Chang model cannot describe the strain softening behavior of frozen sand clay;an improved Duncan-Chang model is proposed. This model can describe not only the strain softening behavior but also the strain hardening behavior of frozen sand clay. Moreover,its modeling precision is better than those of Duncan-Chang model and the general hyperbolic model. Due to pressure melting,shear strength of frozen sand clay nonlinearly changes with increasing confining pressures. In order to solve the problem that linear Mohr-Coulomb criteria can not exactly reflect the shear strength of frozen sand clay,a nonlinear Mohr criterion of frozen sand clay is presented. The results calculated by the nonlinear Mohr criterion of frozen sand clay illustrate that it has higher precision and can more exactly describe the shear strength of frozen sand clay than the linear Mohr-Coulomb criterion.

Stress-strain relationships and nonlinear mohr strength criterion of frozen sand clay

Cyclic direct shear behaviors of an artificial frozen soil-structure interface under constant normal stress and sub-zero temperature

The shear behavior of rock mass significantly depends upon the surface roughness of rock joints which is generally characterized by the anisotropy characteristic and the scale effect. The large-scale natural rock joint surfaces, at Qingshi Town, southeast of Changshan County, Zhejiang Province, China, were used as a case study to analyze the roughness characteristics. A statistical assessment of joint roughness coefficient (JRC) indicated the roughness anisotropy of different sized rock joints. The lower limit ( ) was regarded as the determinate information, and the difference between lower and upper limits represented indeterminate information. The neutrosophic number (NN) was calculated to express the various JRC values. The parametric equations for JRC anisotropic ellipse were presented based on the JRC statistical assessment of joint profiles of various orientations. The JRC values of different sized joint samples were then quantitatively described by the neutrosophic function. Finally, a neutrosophic parameter for evaluating the scale effect on the surface roughness anisotropy was introduced using the ratio of maximum directional roughness to minimum directional roughness. The case study indicates that the proposed method has the superiority in moving forward from subjective assessment to quantitative and objective analysis on anisotropy characteristic and scale effect of joint surface roughness.

/pdf/neutrosophic-function-with-nns-for-analyzing-and-expressing-3xhb3apefc.pdf

Neutrosophic Function with NNs for Analyzing and Expressing Anisotropy Characteristic and Scale Effect of Joint Surface Roughness

The shear behaviors of concrete-frozen soil interface are important for analyzing the performance of engineering structures buried in the frozen ground. In this paper, a series of direct shear tests were carried out to determine the concrete-soil interface behaviors at different test temperatures (19°C, −1°C, −3°C, and −5°C) and initial water contents (9.2%, 13.1%, 17.1%, and 20.8%) of soils. The interface shear behaviors, including the shear stress versus horizontal displacement, interface cohesion, and interface friction coefficient, were analyzed based on the test results. Then, a simple, nonlinear model was proposed and verified for the interface shear behaviors. The results show that the effect of initial water content and test temperature on the interface shear behavior is significant, and the peak stress increases with the increasing initial water content and decreasing test temperature. The interface cohesion is sensitive to the test temperature and initial water content, while the interface friction coefficient is insensitive to both the factors. The parameters of the simple nonlinear model can be gained by back-analyzing the test results. The predictions made by the proposed model are found to be in good agreement with the experimental results.

/pdf/modeling-of-concrete-frozen-soil-interface-from-direct-shear-4k4fdfmtxp.pdf

E.A. Vorobyov

Papers

Mechanical Properties of Frozen Coarse-Grained Soils