Abstract

The columnar joints in Baihetan hydropower station are primary tensile joints since they were formed during the process of lava condensation. Understanding the influence of columnar jointed rock mass (CJRM) on the mechanical response and failure modes is the basis for designing of associated engineering works. Hence, the structural characteristics of Baihetan CJRM were analyzed by carrying out a geological survey at first. Three groups of numerical models capable of reflecting the structural characteristics of CJRM were then established to analyze the mechanical and failure characteristics. The results in this study showed that: (1) Irregularity of columnar basalt restricted crack propagation on columnar joints and also led to stress concentration in the distorted parts, and thus, damage of basalt columns; (2) when the included angle between direction of concentrated defect structures in CJRM and uniaxial stress was large, the defect structures can prevent crack propagation on columnar joints, and the failure of defect structure can cause the overall failure of the rock mass; and (3) under the condition of same columnar structure and included angle, the peak strength of models with microcracks and structural plane was low and the irregular shape of columnar joints decreased the anisotropy of mechanical parameters.

Highlights

  • Baihetan hydropower station on Jinsha River is located in the gorge between Ningnan County, Sichuan Province, and Qiaojia County, Yunnan Province, southwest China

  • According to in situ tests, the defect structures in Columnar jointed rock masses (CJRM) are unfilled structures composed of the same material and tightly embedded with each other

  • The failures of structural plane and steeply-dipping microcracks are dominant in the rock mass

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Summary

Introduction

Baihetan hydropower station on Jinsha River is located in the gorge between Ningnan County, Sichuan Province, and Qiaojia County, Yunnan Province, southwest China. The research into mechanical properties and failure characteristics of brittle materials cover three aspects: In situ tests, laboratory tests, and numerical simulations [2,3,4]. Jiang et al [6] explored the anisotropic characteristics of CJRM formation in Baihetan hydropower station, including aspects of geometrical rock structure, deformation, and strength anisotropy. [9] proposed an original model of Abaqus to simulate the failure of brittle material, such as glasses and concrete This model is able to account for the geometrical and mechanical properties of reference connection specimens. The influence of structural characteristics of CJRM on its failure modes and anisotropic mechanical properties were analyzed in detail. The failure characteristics of CJRM in different directions under uniaxial compression were summarized

Distribution Characteristics of CJRM at Baihetan Hydropower Station
The Roughness of Columnar Joints failure of jointed rock mass
Mechanical
Elasto-brittle damage constitutive law of element to uniaxial stress:
Calibration of Mechanical Parameters for Basalt Columns
Calibration of Mechanical Parameters for Defect Structures
Damage Evolution in CJRM
11. Simulation
14. Numerical without microcracks and structural planes
Failure Characteristics of Generalised CJRM Model
15. Numerical
Mechanical Properties
Stress-Strain Curves
Discussions
Conclusions
Full Text
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