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Special Issue "Risk Management Technologies for Deep Excavations in Water-Rich Area"

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A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydrogeology".

Deadline for manuscript submissions: 20 December 2023 | Viewed by 12027

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Special Issue Editors

Prof. Dr. Yixian Wang

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Guest Editor

School of Civil Engineering, Hefei University of Technology, Hefei 230009, China
Interests: rock mechanics; soil mechanics; tunnelling technology; ground improvement; carbon capture and storage; underground infrastructures
Special Issues, Collections and Topics in MDPI journals

Dr. Panpan Guo

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Guest Editor

School of Civil Engineering, Hefei University of Technology, Hefei, China
Interests: geotechnical engineering; tunnelling; excavation; soil mechanics; rock mechanics

Prof. Dr. Hang Lin

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Guest Editor

School of Resources and Safety Engineering, Central South University, Changsha 410083, China
Interests: numerical calculation of geotechnical engineering; joint mechanics; slope engineering; tunnel engineering; safety management and prediction system
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Yanlin Zhao

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Guest Editor

Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines, Work Safety Key Laboratory on Prevention and Control of Gas and Roof Disasters for Southern Coal Mines, Hunan University of Science and Technology, Xiangtan 411201, China
Interests: rock mechanics; rock fluid mechanics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Due to the adverse effect of high hydraulic head pressure in water-rich area, deep excavations in that area inevitably involve a relatively high risk of instabilities, such as water burst, mud gushing, and sand inrush, which might result in large-scale failures imperiling human lives, personnel property, and economic balance. Risk management for deep excavations in water-rich areas is a systematic process of identifying potential hazards and mitigating them in order to maintain a specified degree of safety throughout the duration of the project. In engineering practice, the commonly adopted countermeasure against the detriment of water infiltration induced by great water head difference is carrying out dewatering during the construction of deep excavation in water-rich areas. However, improper dewatering can yield unbalanced ground stress, which gives rise to overlarge ground movements, lateral wall deformations, and collapse or failure of adjacent buildings and infrastructures.

The objective of this Special Issue is to provide a platform for researchers to report new advances in risk management technologies for deep excavations in water-rich areas and their many applications. Both original research and review articles are welcome.

Potential topics include but are not limited to the following:

Role of groundwater in affecting the stability of deep excavations
Method for assessing the risks in various stages
Identification of hazards during the entire phase
Precautions for reducing the risk of certain dangers
In situ instrumentation methods and result interpretation
Environmental effects of deep excavations
Mechanism of soil–groundwater–structure interactions
Innovation of excavation supporting systems
Numerical modeling of three-dimensional deep excavation behavior
Analytical methods for predicting risks and responses

Prof. Dr. Yixian Wang
Dr. Panpan Guo
Prof. Dr. Hang Lin
Prof. Dr. Yanlin Zhao
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

groundwater
hydrogeology
geotechnical engineering
deep excavation
risk management
ground deformation

Published Papers (12 papers)

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Open AccessArticle

Detection of Landfill Leachate Leakage Based on ERT and OCTEM

and

Water 2023, 15(9), 1778; https://doi.org/10.3390/w15091778 - 05 May 2023

Viewed by 763

Abstract

Leakage in the impervious layer of a domestic waste landfill seriously pollutes the soil and groundwater. Therefore, it is necessary to carry out rapid nondestructive leakage location detection. In this research, the electrical resistivity tomography (ERT) method and the opposing-coils transient electromagnetic method (OCTEM) were used to detect the leakage location. The inversion sections of both methods showed a clear low–middle–high resistivity spectrum in the longitudinal direction that could be used to speculate the distribution pattern of the upper waste body layer, the bottom impermeable layer, and the lower limestone layer. The leakage area was identified in Zone B of the landfill on the basis of inversion results and drilling verification results. The results indicate that OCTEM and ERT were both sensitive to leakage detection. However, OCTEM had higher longitudinal resolution and more refined inversion results, resulting in more effective delineation for the location of the damage and leakage of the impervious landfill layer, thereby providing a new technical basis for landfill leakage detection. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessArticle

Application and Automatic Monitoring and Analysis of Hybrid Support Structure in Ultra-DEEP Foundation Pit Engineering in the Lanzhou Area under Complex Environmental Conditions

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Water 2023, 15(7), 1335; https://doi.org/10.3390/w15071335 - 28 Mar 2023

Viewed by 779

Abstract

This paper takes the deep foundation pit project of Lanzhou Hospital of Traditional Chinese Medicine as the background. The design and construction of the foundation pit is relatively difficult due to the complex environment around the pit, the dense surrounding buildings, the complex underground soil layer and the influence of groundwater on the pit. In order to detect problems in the construction process, the pit was monitored in real time through an automated monitoring system for the whole process of excavation and backfilling of the pit. The analysis of the actual monitoring data shows that: (i) the support scheme of bored pile + prestressed anchor cable support combined with concrete corner bracing can meet the design of this type of foundation pit without causing disturbance to the surrounding buildings; (ii) combined with the actual case of the influence of groundwater on the excavation process of the foundation pit, it proves that the real-time measurement by the robot can timely detect the safety hazards caused by external factors during the construction process of the foundation pit. The project is a very important one for deep pits and complex pits. This project provides a good reference case for deep foundation pits and foundation pit projects in complex environments. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessArticle

Mining Leachates Effect on the Hydraulic Performance of Geosynthetic Clay Liners under Different Temperatures

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Water 2023, 15(6), 1132; https://doi.org/10.3390/w15061132 - 15 Mar 2023

Viewed by 756

Abstract

Geosynthetic clay liners (GCLs) are often used as anti-seepage systems in landfills and at the bottom of tailing ponds. The anti-seepage performance of GCL will change under different temperatures. In this study, bentonite was mixed with test solutions at different temperatures to measure the basic performance indexes of bentonite components and analyze the permeability. The composition and micro-structure of bentonite at different temperatures were analyzed by X-ray diffraction, X-ray fluorescence spectrum, and SEM, and the change rule of permeability property with the mine leachates at different temperatures was understood by combining the macro-measured parameters with the microscopic analysis results. The research results indicate that the fluid loss of two bentonites increased with the increasing temperature due to the inhibition of ion exchange between bentonite and mixture by the increased temperature. The swelling index of the bentonite increased at high temperatures. The micro-structure analysis showed the increase of the pore size attributed to high temperature, and the uneven distribution of the pore size resulted in the increase of the intrinsic permeability. The study would provide the reference for the application of GCL in mining. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessFeature PaperArticle

Failure Characteristics of the Water-Resisting Coal Pillar under Stress-Seepage Coupling and Determination of Reasonable Coal Pillar Width

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Water 2023, 15(5), 1002; https://doi.org/10.3390/w15051002 - 06 Mar 2023

Cited by 1 | Viewed by 683 | Correction

Abstract

Groundwater inrush hazard has always been a great threat to the construction of vertical shafts in coal mines. Generally, the failure of the water-resisting coal pillar under coupled stress-seepage conditions around the vertical shaft is the main reason for the generation of the water inrush channel. In order to understand the mechanical behaviors of the water-resisting coal pillar, the strength of typical coal affected by the size and water content was investigated, and the stress sensitivity of permeability was investigated by a stress-seepage coupling test. The stress field and deformation of the water-resisting coal pillar were investigated by numerical simulation, the stability of the water-resisting coal pillars with different widths was evaluated, and the reasonable width of the coal pillars under coupled stress-seepage condition was determined. Results show that the water content and coal pillar width have a great influence on the mechanical characteristics of coal samples. Under the conditions of lower water content and larger coal sample width, the coal sample presents higher strength, smaller axial deformation, smaller permeability and porosity, and weak sensitivity to stress. The simulation results show that the boundary of the main roadway at the end of the coal pillar is dominated by tensile stress, and fractures can significantly contribute to the destruction of coal pillars. With the increase in the width of the water-resisting coal pillar, the internal damage variable, maximum tensile stress, porosity, and average water flow velocity of the coal pillar decrease, which reduces the risk of water inrush and improves the safety of the water-resisting coal pillar. An evaluation model of the reasonable width of the water-resisting coal pillar under the stress-seepage coupling was proposed, and the model was verified by the shear slip law and experimental results. This study provides theoretical and experimental guidance for the risk management of groundwater inrush disaster during the construction of vertical shafts in coal mines. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessArticle

Impact of the Boreholes on the Surrounding Ground

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Water 2023, 15(1), 188; https://doi.org/10.3390/w15010188 - 02 Jan 2023

Viewed by 1238

Abstract

The infrastructures that were constructed decades ago do not meet the present structural benchmark, and they need to be demolished. In order to reclaim these lands, the existing pile foundations must be removed; otherwise, the land will lose its value. Since the piles are pulled out, vacant spaces are created in the ground. This causes the surrounding ground to experience settlement, jeopardizing its stability. The degree of influence depends upon the number of boreholes, the saturated condition of the ground, the time period of the vacant condition, the presence of loading, etc. It is important to understand the scope of the probable settlement under various situations. This study focused on determining the amount of displacement and its range for three different saturated soil types under loaded and unloaded conditions using the finite element method (FEM) analysis. It was observed that stiff ground underwent maximum deformation, while soft ground experienced the maximum influence from external factors. Moreover, the presence of loading not only increased the displacement amount and range, but it also caused a change in the location of the maximum displacement. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessArticle

Fast Recognition on Shallow Groundwater and Anomaly Analysis Using Frequency Selection Sounding Method

Lu Yulong

Yang Tianchun

Abdollah Taheri Tizro

and

Liu Yang

Water 2023, 15(1), 96; https://doi.org/10.3390/w15010096 - 28 Dec 2022

Cited by 1 | Viewed by 1351

Abstract

The validity of the frequency selection method (FSM) in shallow (<150 m) groundwater exploration was illustrated by practical applications, and the relationship between potential electrode spacing MN and groundwater depth in FSM sounding method was analyzed and preliminary theoretical research was carried out by a simple geologic-geophysical model of sphere. Firstly, under the combined action of horizontal alternating electric field and alternating magnetic field, a simplified geophysical model of low resistivity conductive sphere in homogeneous half space was established, and the forward calculation was performed on the FSM sounding curve. Then, the water yield of 131 wells in the application of FSM in the Rural Drinking Water Safety Project of 12th Five-Year Plan in Guangxi Province was counted. In addition, detailed tabular statistical analysis was carried out on the drilling results of 98 drilling wells, and the relationship between potential electrode spacing MN at abnormal sounding curve and actual drilling water depth was compared and studied. Theoretical analysis and practical application show that FSM has obvious effectiveness in shallow groundwater exploration, and it is an effective method to determine shallow groundwater well locations in the future. The cause of FSM anomaly is the comprehensive effect of the natural 3D alternating electromagnetic signal underground. At the same time, the practical statistics show that there is 1:1 approximation between the size of potential electrode spacing MN at the anomaly curve of the frequency selection method and the actual drilling water depth, which verifies the correctness of the theoretical simulation results. FSM could be widely used in the shallow groundwater exploration in the future, and it is an effective, non-destructive, fast, and low-cost geophysical method. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessFeature PaperArticle

A Machine Learning Method for Engineering Risk Identification of Goaf

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Water 2022, 14(24), 4075; https://doi.org/10.3390/w14244075 - 13 Dec 2022

Viewed by 739

Abstract

The risk evaluation indexes of goaf are multi-source and have complex mutual internal correlations, and there are great differences in the risk identification of goaf from different mines among the various influencing factors. This paper mainly focuses on principal component analysis (PCA) and the differential evolution algorithm (DE), while a multi-classification support vector machine (SVM) is adopted to classify the risks of goaf. Then, the K-fold cross-validation method is used to prevent the overfitting of selection in the model. After the analysis, nine factors affecting the risk identification of goaf in a certain area of East China were determined as the primary influencing factors, and 120 measured goafs were taken as examples for classifying the risks. More specifically, the classification results show that: (1) SVM has the useful ability of generalization, especially when solving the problems of overfitting, and it is easy to fall into the local minima under the conditions of small samples; (2) PCA is employed to realize the intelligent dimensionality reduction and denoising of multi-source impact indicators for goaf risk identification, which immensely improves the prediction accuracy and classification efficiency of the model; (3) after using the DE, the optimal solutions of the problems to be optimized are automatically obtained through the global optimization search mechanism, namely, the kernel function parameter, ‘γ’, and the penalty factor, ‘C’, of the SVM, which further verifies that the characteristics of clear logic, strong convergence, and good robustness can be found in the DE. As demonstrated, this method has the advantages of guiding significance and application value for goaf risk identification. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessArticle

Design and Field Monitoring of a Pile–Anchor–Brace Supporting System in a Soft Soil Area

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Water 2022, 14(23), 3949; https://doi.org/10.3390/w14233949 - 04 Dec 2022

Viewed by 985

Abstract

With the continuous development of urbanization and the rapid development of science and technology, the requirements for foundation pit engineering are getting higher and higher. Foundation pit engineering is gradually developing in the direction of larger area and deeper excavation. In engineering examples, the combined supporting structure of a pile–brace and pile–anchor for foundation pits is widely used, while the engineering examples supported by a pile–anchor–brace supporting system are less frequently used. Based on a super-large deep foundation pit project in Yancheng City, Jiangsu Province, China, according to the surrounding environmental conditions, the foundation pit support scheme, and on-site construction situation, the design and on-site monitoring of the pile–anchor–brace supporting system were introduced and analyzed. The results show that: (1) the deformation of the pile–anchor–brace supporting system shows an obvious spatial effect, and the horizontal displacement of the pile and soil of the long side direction is greater than the short side direction; (2) in the initial state, the deep horizontal displacement of the soil is in the form of a ‘cantilever’, but in the later stage it changed to the form of a ‘drum belly’, and both the brace and anchor cable can limit the displacement of the soil effectively; (3) the axial force of the brace develops rapidly in the initial stage, but its development tends to be gentle after the completion of the first anchor cable construction. Through on-site monitoring, it was found that the axial force of the ring brace was larger than that of the corner brace, which was larger than the opposite brace; and (4) the development trend of the axial force for the two rows of anchor cables is quite different. The average axial force of the first row of anchor cables is greater than the second row of anchor cables, and the development trend of the first row of anchor cables is steep first and then gentle, while the change trend of the second row of anchor cables is just the opposite. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessFeature PaperArticle

Predicting Ground Surface Settlements Induced by Deep Excavation under Embankment Surcharge Load in Flood Detention Zone

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Water 2022, 14(23), 3868; https://doi.org/10.3390/w14233868 - 27 Nov 2022

Cited by 3 | Viewed by 1594

Abstract

In this paper, a simplified prediction formula of ground settlement induced by deep foundation pit excavation is proposed, especially suitable for ground overloading near a foundation pit, such as embankment surcharge load, which is carefully considered via the means of load equivalence. The ground settlement induced by foundation pit excavation and embankment surcharge load is determined by the modified skewness prediction formula and the simplified Boussinesq solution, respectively, and it is assumed that no coupling effect exists between the two settlement sources. In addition, this paper improves the determination of the maximum settlement location by combining calculus and curve fitting, replacing the existing prediction formula which relies heavily on engineering experience to determine the maximum settlement point. The predicted value obtained using this method comes close to the measured value, and the deviation of the maximum surface settlement value is controlled within about 5% in the three cases introduced, of which the accuracy is higher than the existing prediction formula. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessFeature PaperArticle

Stability of Braced Excavation Underneath Crossing Underground Large Pressurized Pipelines

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Water 2022, 14(23), 3867; https://doi.org/10.3390/w14233867 - 27 Nov 2022

Cited by 1 | Viewed by 918

Abstract

The practice of deep-braced excavation in congested urban environments involves frequently buried pipelines, which can exert a significant effect on the performance of the excavation. The objective of this paper is to investigate the performance of a 12.5-m-deep-braced excavation spanned by two shallowly buried large-diameter pressurized pipelines. A suspension structure is installed within the excavation to protect the in situ pipelines during the construction. The excavation performance is investigated by performing a three-dimensional finite element analysis. The finite element method is verified based on the observations at the site. The results indicate that, as expected, the excavation support structures displace together with varying degrees of deformation toward the excavated area. The strut shear forces are found to be distributed axially in linear manners, while the strut bending moments are in symmetric manners. The benefit of using the proposed pipeline suspension structure is demonstrated. By using this structure, pipeline deformation can be well controlled, and the structural integrity and safety of the pipelines can be ensured. This benefit depends on the convenient operation in that the elevation of the cork base of the pipeline suspension structure is stably lowered during the construction process. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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Open AccessArticle

Risk Assessment for Critical Flood Height of Pedestrian Escape in Subway Station

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Water 2022, 14(21), 3409; https://doi.org/10.3390/w14213409 - 27 Oct 2022

Cited by 2 | Viewed by 999

Abstract

The escape of pedestrians in the subway station is hampered by floods created by heavy rain. In order to explore the critical flood level in a subway station so that pedestrians can escape safely, the case study of the Mingxiu Road subway station in Nanning, China, was conducted using numerical simulation techniques. In total, 30 groups of sample pedestrians with different walking speeds and numbers were randomly generated by the Monte Carlo method, and 3D simulation software was used for escape simulation. The simulated escape data were put into the SVM model, and the maximum pedestrian capacity and minimum speed of pedestrians were solved successfully with different conditions of the Mingxiu Road subway station. Then, a 1:1 contour model of the pedestrian was constructed to simulate the flood resistance of the pedestrian escaping at the minimum speed. The flood resistance and the friction force between the pedestrian and the ground were compared to calculate the critical escape flood level height, and the critical escape flood level height of an adult, child, and elder was 87.4 cm,75.5 cm, and 83.0 cm, respectively. Full article

(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Area)

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