Investigation on the Influence of Temperature and Confining Pressure on the Hydraulic Conductivity of the Integrated and Fractured Jurassic Conglomerates

Ilaria Fuoco,Wanghua Sui,Jiawei Liu,Dingyang Zhang

doi:10.1155/2021/8858030

Abstract

This paper presents an experimental investigation on the properties of hydraulic conductivity and permeability of conglomerates under different temperatures and confining pressures with integrated samples and samples with shear failure. Constant head tests were carried out in a temperature-controlled triaxial cell with samples obtained from the Zhuxianzhuang Coal Mine. Five levels of temperatures (10°C, 20°C, 28°C, 35°C, and 50°C) and three levels of confining pressures (3 MPa, 5 MPa, and 7 MPa) were chosen for the tests. The results show that there is a negative relationship between hydraulic conductivity and confining pressure with both original and shear failure samples. An inflection point of 35°C is found in the relationship between the flow rate and temperature. However, with increasing temperature conditions, hydraulic conductivity first increases and then decreases at 50°C with the intact sample, while hydraulic conductivity first decreases from 20°C and then increases with the shear failure sample. Finally, nonlinear regression equations of hydraulic conductivity and temperature were obtained under different confining pressures.

Highlights

Multiple fields, such as temperature, stress, and seepage, are coupling around rock masses
The hydraulic conductivity of porous media is a fundamental property that determines the durability of these media and the flow rate through them
The results show that the hydraulic conductivity is not sensitive to the heating rate, but there is a positive relationship between the hydraulic conductivity and temperatures of 23°C, 40°C, 60°C, and 80°C

Summary

Introduction

Multiple fields, such as temperature, stress, and seepage, are coupling around rock masses. Based on existing theory and practice, an investigation of the characteristics of permeability in both an integrated and a fractured rock mass under the combined interactions of seepage, stress, and temperature is necessary for understanding the stability of rock slopes and underground surroundings. Understanding the permeability of a fractured rock mass is one of the fundamental issues in the study of fluid flow in fractured rock masses. Within a certain depth, temperature increases with depth, while in different stratigraphic structures, the surrounding pressure changes. The confining pressure and the ambient temperature of the rock mass are different, which affects the permeability characteristics, and these factors cannot be ignored. The hydraulic conductivity of porous media is a fundamental property that determines the durability of these media and the flow rate through them

Methods

Results

Discussion

Conclusion