Model Test of Anchoring Effect on Zonal Disintegration in Deep Surrounding Rock Masses

Abstract

The deep rock masses show a different mechanical behavior compared with the shallow rock masses. They are classified into alternating fractured and intact zones during the excavation, which is known as zonal disintegration. Such phenomenon is a great disaster and will induce the different excavation and anchoring methodology. In this study, a 3D geomechanics model test was conducted to research the anchoring effect of zonal disintegration. The model was constructed with anchoring in a half and nonanchoring in the other half, to compare with each other. The optical extensometer and optical sensor were adopted to measure the displacement and strain changing law in the model test. The displacement laws of the deep surrounding rocks were obtained and found to be nonmonotonic versus the distance to the periphery. Zonal disintegration occurs in the area without anchoring and did not occur in the model under anchoring condition. By contrasting the phenomenon, the anchor effect of restraining zonal disintegration was revealed. And the formation condition of zonal disintegration was decided. In the procedure of tunnel excavation, the anchor strain was found to be alternation in tension and compression. It indicates that anchor will show the nonmonotonic law during suppressing the zonal disintegration.

Physical Model Test on the Deformation and Fracturing Process of Underground Research Laboratory during Excavation and Overloading Test

“…The properties of the prototype and analogue bolt are listed in Table 3. The physical model was paved, compacted and air-dried layer-by-layer to ensure the integrity and homogeneity of the surrounding rock [48][49][50][51][52][53].…”

“…Due to the limitation of the bolt installation technology and model chamber size, the bolt support is frequently simulated by pre-embedding the bolt [31,50,52]. The detailed procedures of pre-embedding the bolt are as follows: determining the position of preembedding the bolt (see Figure 4a); drilling holes in the position of the pre-embedded bolt (see Figure 4b); inserting similar materials of the bolt (see Figure 4c); injecting grouting similar materials (see Figure 4d); and air-drying grouting similar materials.…”

Physical Similarity Simulation of Deformation and Failure Characteristics of Coal-Rock Rise under the Influence of Repeated Mining in Close Distance Coal Seams

“…For example, Lin et al [14] simulated roadway excavation in a coal mine, used a selfmade model to build a test model, which was controlled by microcomputer and employing an electro-hydraulic servo universal testing machine to load. Chen et al [15] simulated roadway excavation with high geostress, which was supported by an anchor used selfmade true three-dimensional loading model test system. Pornkasem Jongpradist et al [16] studied the fracture mechanism of surrounding rock for high internal pressure roadway through establishing physical similarity model.…”

Failure Mechanism and Numerical Simulation of Splitting Failure for Deep High Sidewall Cavern Under High Stress

“…With its advantages of visualization, intuition and realism, the geomechanical model test is of great significance to the study of damage mechanism of underground caverns (Chen et al 2013a(Chen et al , 2013b(Chen et al and 2013cZhang et al 2013 andGao et al 2018). The method can also simulate excavation and unloading under real three-dimensional high ground stress conditions, reproduce the damage pattern of the cavern, and capture the variations in deformation and stress (Zhang et al, 2019a(Zhang et al, , 2019b.…”