Development of a Soft-Rock Weathering Test Apparatus

Abstract

This paper presents a weathering test apparatus developed for testing the deformation and shear strength behavior of rockfill materials for high dams under coupling actions of drying/wetting cycles, cooling/heating cycles, and vertical loads. The apparatus was integrated with a vertical load unit, a lateral shear unit, a drying/wetting circulation unit, and a cooling/heating circulation unit. A cell was designed to perform direct shear tests under normal pressures up to 5.5 MPa after long‐term weathering associated with wide variations in temperature and moisture content. It accommodates specimens 150 mm in diameter and 150 mm in height. The related experimental procedures and calibration of the device are discussed. Results of tests performed on an argillaceous siltstone used as the rockfill material for a 261.5 m high dam are presented in order to highlight the features of the apparatus and the weathering effects on soft rock.

Deformation and shear strength of rockfill materials composed of soft siltstones subjected to stress, cyclical drying/wetting and temperature variations

“…Table 1 lists the test program. Testing procedures can be found in Zhang et al (2014). Five groups of tests were performed on the argillaceous siltstone under various conditions.…”

Support Technique of Horse Head in Weakly Cemented Soft Rock

“…So it is urgent to put forward the effective and simple support technique to determine the strain softening effect of weakly cemented soft rock. It has great difficulty of supporting the horse head in weakly cemented soft rock [5]. At the same time, and the cost of horse head engineering is much higher than the general tunnel because of its high importance and its long service life.…”

Study on Damage Characteristics of Unstable Rocks under Excitation Effect

“…And in terms of unstable rock collapse source failure mechanism, research achievements are less open report. Qiang XU considered that there were key blocks on a steep cliff at the situation of outsize landslide from the cocktail mountain located in Wulong of Chongqing [2]; Yong-xing ZHANG analyzed the impact on the tensile stress in slope and the development depth of rock cavity to the formation and the destruction of differential weathering unstable rock [3]; Frayssines and Hantz analyzed failure mechanism of limestone on steep slope [4]; Hong-kai CHEN discussed damage characteristics [5] from dominant fissure top and fatigue crack characteristics under the action of crack hydraulic pressure based on damage and fracture mechanics [6], and proposed stability analysis method of unstable rock fracture [7]. In recent years, research has shown that unstable rock damage could abruptly release of energy, and the energy passed around in the form of excitation wave, which could affect the safety state of adjacent unstable rock.…”