Investigation on jet grouting support strategy for controlling time‐dependent deformation in the roadway

Sun³

et al. 2021

Sustainability

Self Cite

High-efficiency maintenance and control of the deep coal roadway surrounding rock stability is a reliable guarantee for sustainable development of a coal mine. However, it is difficult to control the stability of a roadway that locates near a roadway with large deformation. With return air roadway 21201 (RAR 21201) in Hulusu coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to study pressure relief effect on the surrounding rock after the severe deformation of the roadway. Besides, the feasibility of excavating a new roadway near this damaged one by means of pressure relief effect is also discussed. Results showed that after the strong mining roadway suffered huge loose deformation, the space inside shrank so violently that surrounding rock released high stress to a large extent, which formed certain pressure relief effect on the rock. Through excavating a new roadway near this deformed one, the new roadway could obtain a relative low stress environment with the help of the pressure relief effect, which is beneficial for maintenance and control of itself. Equal row spacing double-bearing ring support technology is proposed and carried out. Engineering practice indicates that the new excavated roadway escaped from possible separation fracture in the roof anchoring range, and the surrounding rock deformation of the new roadway is well controlled, which verifies the pressure relief effect mentioned. This paper provides a reference for scientific mining under the condition of deep buried and high stress mining in western China.

Section: Introductionmentioning

confidence: 99%

Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

Yang¹,

Sun³

et al. 2021

Sustainability

Self Cite

“…To investigate the failure of soft rock mass roadway in deep mines, some methods such as theoretic analysis [6], field tests [7][8][9], physical simulation models [10,11], and numerical modeling were presented and utilized. Nowadays, different numerical simulation methods were developed and adopted due to their special advantages including low costs, high efficiency, and repeatability [12,13].…”

Section: Introductionmentioning

confidence: 99%

Failure Mechanisms of Rheological Coal Roadway

Sun

et al. 2020

Sustainability

Self Cite

The roadway instability in deep underground conditions has attracted constant concerns in recent years, as it seriously affects the efficiency of coal mining and the safety of personnel. The large rheological deformations normally occur in deep roadway with soft coal mass. However, the failure mechanism of such roadways is still not clear. In this study, based on a typical soft coal roadway in the field, the in-situ measurements and rock mass properties were obtained. The rheological deformation of that roadway was revealed. Then a time-dependent 3D numerical model was established and verified. Based on the verified model, the deformation properties and evolutionary failure mechanism of deep coal roadway were investigated in detail. The results showed that the deformation of the soft coal roadway demonstrated rheological behavior and the applied support structures failed completely. After roadway excavation, the maximum and minimum stresses around the roadway deteriorated gradually with the increase of time. The failure zones in soft coal mass expanded increasingly over time, which had a negative effect on roadway stability in the long-term. According to the findings, helpful suggestions were further presented to control the rheological deformation in the roadway. This research systematically reveals the instability mechanism of the deep coal roadway and provides some strategies for maintaining roadway stability, which can significantly promote the sustainability of mining in deep underground coal mines.

“…Cemented paste backfill (CPB) is widely used for mining operations in underground metal mines, in which tailings are normally used as main aggregates and they are mixed with cementitious material and water [1]. CPB is normally filled into the underground stope, and thus, it plays a critical role in supporting the roof and surrounding rock mass after a certain period of dehydration and consolidation [2][3][4][5]. Compared with other backfill materials, CPB is an eco-friendly and economic mine composite due to the maximum utilization of mine waste, which attracts much attention these years [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Development of an Ensemble Intelligent Model for Assessing the Strength of Cemented Paste Backfill

Sun

Advances in Civil Engineering

et al. 2020

Self Cite

Cemented paste backfill (CPB) is an eco-friendly composite containing mine waste or tailings and has been widely used as construction materials in underground stopes. In the field, the uniaxial compressive strength (UCS) of CPB is critical as it is closely related to the stability of stopes. Predicting the UCS of CPB using traditional mathematical models is far from being satisfactory due to the highly nonlinear relationships between the UCS and a large number of influencing variables. To solve this problem, this study uses a support vector machine (SVM) to predict the UCS of CPB. The hyperparameters of the SVM model are tuned using the beetle antennae search (BAS) algorithm; then, the model is called BSVM. The BSVM is then trained on a dataset collected from the experimental results. To explain the importance of each input variable on the UCS of CPB, the variable importance is obtained using a sensitivity study with the BSVM as the objective function. The results show that the proposed BSVM has high prediction accuracy on the test set with a high correlation coefficient (0.97) and low root-mean-square error (0.27 MPa). The proposed model can guide the design of CPB during mining.