A Novel Approach for Predicting the Height of the Water-Flow Fracture Zone in Undersea Safety Mining

Bing Dai,Ying Chen

doi:10.3390/rs12030358

Abstract

The height of the water-flow fracture zone (WFZ) is an important reference for designing the size of a waterproof crown pillar. Once the WFZ is connected with the sea, there will be catastrophic consequences, especially for undersea mining. This study suggests using a rotating forest (RoF) model to predict the height of the WFZ for the evaluation of the size of a waterproof crown pillar. To train and test the RoF model, five indicators with major influencing factors on undersea safety mining were determined, 107 field-measured mining datasets were collected, 75 (70%) datasets were used for training, and 32 (30%) datasets were used for model testing. At the same time, the random forest ensemble algorithm (RFR) and support vector machine (SVM) models were introduced for comparison and verification; in the end, the tested results were evaluated by RMSE (root-mean-square error) and R2. The comparison shows that the predicted results from the RoF model are significantly better than those from the RFR and SVM models. An importance analysis of the impact indicators shows that the mining height and depth have significant impacts on the prediction results. The development height of the WFZ in undersea safety mining was predicted via the RoF model. The predicted results via the RoF model were verified by field observations using panoramic borehole televiewers. The RoF prediction results are consistent with the observation results at all depths. Compared with the other two models, the RoF model has the smallest average absolute error at 2.87%. The results show that the RoF model can be applied to predict the height of the WFZ in undersea mining, which could be an effective way of minimizing the mineral resource waste in the study area and in other similar areas in the world under the premise of mine safety.

Highlights

With the rapid growth of the economy, the demand for mineral resources has continued to increase [1]
The results show that the rotating forest (RoF) model can be applied to predict the height of the water-flow fracture zone (WFZ) in undersea mining, which could be an effective way of minimizing the mineral resource waste in the study area and in other similar areas in the world under the premise of mine safety
After mining an underwater orebody, a goaf can be produced, which will cause the overburden to move, deform, and even break down [5], making it easy to form an overburden mining fracture zone, which may lead to water pouring into the mine, causing water inrush accidents [6]

Summary

Introduction

With the rapid growth of the economy, the demand for mineral resources has continued to increase [1]. As easy-to-mine orebodies are gradually exhausted, orebodies with complicated mining conditions, such as broken orebodies, high-cold orebodies, deep orebodies, and underwater or seabed orebodies, are becoming important mining targets [2,3,4]. With the development of technology and equipment upgrades, the exploitation of underwater mines is gradually increasing. After mining an underwater orebody, a goaf can be produced, which will cause the overburden to move, deform, and even break down [5], making it easy to form an overburden mining fracture zone, which may lead to water pouring into the mine, causing water inrush accidents [6]. The occurrence of water-inrush accidents in mines causes casualties and resource losses and damages the original water and land

Methods

Discussion

Conclusion