Dynamic Compression Properties and Deterioration of Red-Sandstone Subject to Cyclic Wet-Dry Treatment

Bin Du,Guangming Wu,Haibo Bai

doi:10.1155/2019/1487156

Abstract

Rock engineering is usually associated with impact loads induced by blasting, drilling, vibration, or earthquake. In the engineering fields of tunnelling, slopes, dams, and mining, rocks are always subjected to cyclic wet-dry caused by periodical variation in moisture. To study cyclic wet-dry effects on dynamic compression properties and deterioration of red-sandstone, physical tests and dynamic and static tests were conducted after 0, 5, 10, 15, and 20 wet-dry cycles. Changes in physical and mechanical parameters, including P-wave velocity, density, and static and dynamic compression strength, were determined. Deterioration of red-sandstone caused by wet-dry cycles was verified through physicomechanical parameters, and the microscopic features were scanned by SEM techniques. Experimental results showed that the dynamic compression strength increased with the loading rate, but decreased with the increase of wet-dry cycles. In terms of the loading rate, the decay function model was proposed to evaluate the long-term dynamic compression strength of red-sandstone against cyclic wet-dry action. Besides, the function of the loading rate was obtained. Parameters of two models, decay constant and half-life values, were measured accurately.

Highlights

Weathering is defined as the alteration and destruction process of physical and chemical effects on rock and soil materials at or near the earth’s surface. is phenomenon is widespread in rock materials [1,2,3]
Index Property Variations. e variation of P-wave velocity, density, and static uniaxial compression strength is listed in Table 2. e data clearly illustrate that, with the increase of wet-dry cycles, three index properties all decrease to varying degrees
A decay function model taking the loading rate into account was developed for the long-term prediction of dynamic compression strength. e conclusions are as follows: (1) Cyclic wet-dry treatment signi cantly a ects the mechanical and physical properties of red-sandstone

Summary

Introduction

Weathering is defined as the alteration and destruction process of physical and chemical effects on rock and soil materials at or near the earth’s surface. is phenomenon is widespread in rock materials [1,2,3]. As a typical type of the weathering process, cyclic wet and dry are prevalent in rock engineering, especially in fields of tunnelling, slopes, dams, and mining, where rock materials are usually subjected to periodical changes in the moist condition (namely, seasonal changes in groundwater level, water level changes in reservoirs, recurrent rainfall, and ebb and flow of tides) [4, 5]. To accelerate the simulation process, the wet process is usually conducted by submerging rock materials in water for different time (e.g., 12 h, 24 h, 32 h, 48 h, and 3 d). For the oven-dried type, the temperature is generally controlled below 105°C to reduce the temperature effect on mechanical properties of rocks [7, 8]

Methods

Results

Conclusion