h i g h l i g h t s Xanthan gum has limited effect on the soil strength at initial stage. Drying leads to xanthan gum bonding strength and soil cohesion increase. Shrank brittle dry xanthan gum generates strengthening effect variability in soil.

2020)Risk assessment of water inrush in tunnel through water-rich fault based on AHP-Cloud model, ABSTRACTWater inrush is a serious geological disaster in tunnel. Due to the complexity of geological conditions, large-scale water inrush is prone to occur in tunnel through water-rich fault during construction. Based on the comprehensive analysis of influencing factors, 8 evaluation indexes and the corresponding grading criteria are put forward to assess the risk of water inrush, and the risk of water inrush is divided into 4 levels. Synthesizing the standardization process and the analytic hierarchy process (AHP), a novel Cloud model is established to assess the risk of tunnel water inrush. The model is applied to the Longjinxi Tunnel to assess the risk level of water inrush. It is proved that the assessment results of the tunnel through water-rich fault is consistent with the actual situation, which verifies the reliability of evaluation model. ARTICLE HISTORY

The study of the high-performance of biopolymers and current eco-friendly have recently emerged. However, the micro-behavior and underlying mechanisms during the test are still unclear. In this study, we conducted experimental and numerical tests in parallel to investigate the impact of different xanthan gum biopolymer contents sand. Then, a numerical simulation of the direct tensile test under different tensile positions was carried out. The micro-characteristics of the biopolymer-treated sand were captured and analyzed by numerical simulations. The results indicate that the biopolymer can substantially increase the uniaxial compressive strength and tensile strength of the soil. The analysis of the microparameters demonstrates the increase in the contact bond parameter values with different biopolymer contents, and stronger bonding strength is provided with a higher biopolymer content from the microscale. The contact force and crack development during the test were visualized in the paper. In addition, a regression model for predicting the direct tensile strength under different tensile positions was established. The numerical simulation results explained the mechanical and fracture behavior of xanthan gum biopolymer stabilized sand under uniaxial compression, which provides a better understanding of the biopolymer strengthening effect.

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