Strength Control Factors of Chlorite Schist under Schistose Structure

Abstract

In tunnel engineering, it is important to understand the influence of schistose structure on the failure strength of chlorite schist. To explore the strength control factors of chlorite schist, this paper firstly analyzes the mineral composition and meso structure of chlorite schist of different weathering states. The results show that the mineral composition of chlorite schist is changed during the weathering process, and that chlorite is an anisotropic rock mass. Next, a series of uniaxial compressive tests were conducted on chlorite schist samples with different bedding angles (the angle between bedding plane and loading direction; θ=0°, 15°, 30°, 45°, 60°, 75°, and 90°), moisture conditions (dry and saturated), and weathering states (strongly weathered and weakly weathered). Based on the test data, the authors discussed the change laws of the rock strength with bedding angle, weathering state, and moisture condition. The main results are as follows: Chlorite schist is a low-anisotropy rock mass, whose compressive strength exhibited a V-shaped trend with the growing bedding angle; the schistose structure is the internal cause of the deformation and the anisotropic or transversely isotropic strength of the schist; the schistose structure is reshaped and further damaged by external factors (e.g. water softening and weathering effects) in engineering. The research findings help to improve the rock stability and support design in tunnel engineering.

Coupling between tectonic activity and diagenetic evolution of a clastic buried hill—a case study from Gubei low buried hill in Jiyang Depression of Bohai Bay Basin

“…Drawing on the previous studies, this paper analyzes the diagenesis of the Permian tight sandstone reservoirs in Gubei low buried hill, Jiyang Depression, and discusses the coupling between buried hill tectonic activity and diagenetic evolution. The following analysis and testing methods were adopted to facilitate the research: core observation, casting sheet observation, X-ray diffractometry (XRD) (Hadi et al 2019;Rathanasalam et al 2019;Yan et al 2020), scanning electron microscopy (SEM) (Al Owais and El-Hallag 2020;Merizgui et al 2019;Wang et al 2019), and energy spectrum analysis. The research results provide a reference for the exploration and development of clastic buried hills.…”

Study on the Effect of Amygdales on Mechanical Characteristics of Basalt Using the Combined Finite‐Discrete Element Method

“…Bubeck et al [26] found that specimens that contain flat pores were weaker if compression was applied parallel to the short axis than if compression was applied parallel to the long axis. Yan et al [28] found that the UCS of samples exhibited a "V-shaped" trend with increasing bedding angle in chlorite schist. e results of this paper have a certain degree of the engineering reference value.…”