Surface Subsidence Prediction Research Articles

Ground Movements Prediction in Shield-Driven Tunnels using Gene Expression Programming

Introduction: The increase in population and traffic in metropolitan areas has led to the development of underground transportation spaces. Therefore, the estimation of the surface settlement caused by the construction of underground structures should be accurately considered. Several methods have been developed to predict tunneling-induced surface settlement. Among these methods, artificial intelligence-based methods have received much attention in recent years. This paper is aimed to develop a model based on Gene Expression Programming (GEP) algorithm to predict surface settlement induced by mechanized tunneling. Methods: For this purpose, Tehran Metro Line 6 was simulated numerically to investigate the effects of different parameters on the surface settlement, and 85 datasets were prepared from numerical simulations. Subsequently, several GEP models were implemented using the obtained datasets from numerical simulations and finally, a model with 30 chromosomes and 3 genes was selected as the optimum model. Results: A comparison was made between obtained maximum surface settlements by the proposed GEP model and numerical simulation. The results demonstrated that the proposed model could predict surface settlement induced by mechanized tunneling with a high degree of accuracy. Conclusion: Finally, a mathematical equation was derived from the proposed GEP model, which can be easily used for surface settlement prediction.

Prediction of Surface Subsidence Due to Mining

Ground subsidence caused by mining is increasing day by day, and some enormous disasters have been brought. Some scholars have carried out some results by a single factor analysis, but did not consider the multi-working conditions, resulting in a certain deviation from the actual project. Accurate and effective prediction of subsidence caused by coal mining is an urgent problem to be solved. In this paper, the main factors affecting surface subsidence in mining area, which are coal seam thickness and mining depth, are studied by means of composite analysis method. At the same time, three-dimensional finite element method is employed to simulate different engineering conditions. According to the simulation maximum value settlements, fitting through MATLAB software, the corresponding predicted models are established. Comparing with the actual engineering survey data, it is proved that the settlement prediction curve is in good agreement with each other. This research has reference value for actual coal mine engineering and construction engineering.

Evaluation Method of Surface Subsidence Degree for Underground Coal Gasification without Shaft

ABSTRACT Underground coal gasification (UCG) is a green mining technology with less interference to the environment of mining area. However, underground coal gasification also can cause surface subsidence, which will affect the mining area environment. Therefore, it is necessary to study the evaluation method of surface subsidence degree of underground coal gasification to provide scientific basis for environment influence assessment of underground coal gasification. However, few current researches are conducted on the evaluation of surface subsidence degree of underground coal gasification (UCG). To solve this problem, this paper firstly proposes the process for assessing surface subsidence degree of UCG, and then offers a new method of surface subsidence prediction of UCG based on continuum-stochastic medium theory by combining the characteristics of strata movement of UCG without shaft. Meanwhile, the new approach was applied to evaluate the subsidence degree of UCG experiment site of Ulanqab mine. It was found that the subsidence area of UCG test site was in Class I damage, and have slight impact on the environment of the mining area. The safety of ground buildings can also be guaranteed. The research results own important theoretical significance for the environment impact assessment caused by underground coal gasification and UCG industrialization.

Numerical and artificial neural network analyses of ground surface settlement of tunnel in saturated soil

The main purpose of this research is to predict the ground surface settlement in tunneling of a single circular tunnel with simultaneous changes in the mechanical properties of soil and geometrical properties of the tunnel section. In this research, numerical and parametric analysis of circular tunneling in frictional–cohesive saturated soil has been investigated using 2D finite element method by ABAQUS. In other words, the behavior of ground surface, considering to change the different values of depth-to-diameter ratio (H/D), soil cohesion, internal friction angle, permeability coefficient, and the influence of these variables on settlement of surface in each model, has been separately evaluated. Then, a multilayer perceptron (MLP) artificial neural network is designed to predict the ground surface settlement. MLP is a type of feedforward artificial neural network utilizing backpropagation technique for training phase, and the Levenberg–Marquardt method is used to reduce the errors and the distance between the network outputs and finite element method results. There are some independent variables in the input layer and a dependent variable in the output layer. The middle layer consists of seven neurons. Finally, the high potential of the artificial neural network with a correlation coefficient of 0.98 is shown in the prediction of ground surface settlement.

Soft computing approach for prediction of surface settlement induced by earth pressure balance shield tunneling

Estimating surface settlement induced by excavation construction is an indispensable task in tunneling, particularly for earth pressure balance (EPB) shield machines. In this study, predictive models for assessing surface settlement caused by EPB tunneling were established based on extreme gradient boosting (XGBoost), artificial neural network, support vector machine, and multivariate adaptive regression spline. Datasets from three tunnel construction projects in Singapore were used, with main input parameters of cover depth, advance rate, earth pressure, mean standard penetration test (SPT) value above crown level, mean tunnel SPT value, mean moisture content, mean soil elastic modulus, and grout pressure. The performances of these soft computing models were evaluated by comparing predicted deformation with measured values. Results demonstrate the acceptable accuracy of the model in predicting ground settlement, while XGBoost demonstrates a slightly higher accuracy. In addition, the ensemble method of XGBoost is more computationally efficient and can be used as a reliable alternative in solving multivariate nonlinear geo-engineering problems.

Prediction of surface subsidence and deformations due to the underground coal mining

Throughout its historical development, mining has faced the problem of moral and material responsibility due to various types of endangerment and damage to the environment. As a result of the underground coal exploitation, a movement of the rock massif above the coal seam, and changes on the terrain surface due to the process of massif stabilizing take place. The process occurs in space and time, from the moment of balance disturbance in the massif, i.e., the beginning of excavation, during excavation, and after the final excavation of deposit, when the equilibrium state is reestablished in the massif. The character and intensity of these movements and principles according to which they are performed, depend on numerous natural and mining-technological conditions, and are specific to each individual coal deposit. Deformations on the terrain surface in the sinkhole occur in the horizontal and vertical directions. Their values serve to determine the vulnerability level of individual objects on the terrain surface. On the basis of the Patarić-Stojanović stochastic method for the predictive subsidence and deformations calculation, an original MITSOUKO program package, supported by the spatial analyses in the Geographic Information System (GIS), was designed. A case study in Sladaja village influenced by the underground exploitation in the coal mine "Rembas"-Resavica, one of the biggest Serbian coal mines, has been chosen. The data processed in the GIS provided determining the module, sense, and direction of the displacements, sinking velocity, and possible effects of subsidence on facilities.

Surface Subsidence Control during Deep Backfill Coal Mining: A Case Study

Deep resource exploitation is imperative, but it is facing with more complicated mining environment and more dangerous mining disturbances to induce the potential catastrophe process. Solid backfill technology, which can control the strata movement and prevent potential hazards, has been used as the primary method in deep mining for surface subsidence control and ecosystem protection. In this study, taking backfill mining area no. 930 in the Tangkou coal mine as background, the probability integral model was adopted to predict the surface subsidence at different mining depths and filling ratios. The filling ratio was designed for deep mining based on the regression analysis of the predicted surface subsidence results. The study shows that the backfilling ratio at the Tangkou deep coal mining area should be controlled at a level greater than 82.5%, and the mining damage to the surface under this condition was analyzed. Furthermore, control strategies for deep backfill mining are proposed in which the backfill density can be enhanced by optimizing the tamping machine, material composition, and tamping process. Finally, the measurement of the backfill mass and surface subsidence showed that the actual filling ratio was controlled at 82.57%, which ensures adequate protection of the surface buildings during the mining process.

Response Analysis of Deep Foundation Excavation and Dewatering on Surface Settlements

Accurate prediction of surface settlements is a primary concern when deep excavations were carrying out under the water table in urban environments for the safety of the work site. The sedimentation deformation due to deep excavation of foundation pit and dewatering occurs as a result of coupling action of the two factors. The study is aimed at revealing the coupling ground response to the two factors and developing empirical correlations for estimating ground deformations. Taking a deep foundation pit of a metro station as an example, surface settlement estimations were calculated by analytical formulas and numerical models. The settlement results by analytical formulas under excavation and dewatering conditions were added linearly to the total settlements. And three‐dimensional coupling numerical models were established by applying commercial software (GMS and MIDAS) to investigate the interaction impact of excavation and dewatering on the sedimentation deformation. Comparing with monitoring data, numerical simulation results match well with the monitoring data. Furthermore, an empirical surface subsidence correlation equation was developed by the polynomial fitting to illustrate the effect contribution on the total surface settlement of foundation excavation and dewatering.

Prediction of Stresses and Settlement for TBM Tunnel Surrounding Soil

In recent years, modern technology in the construction of tunnels using tunnel-boring machines (TBM) is implemented in the practice of civil engineering in large cities which significantly reduces the harmful effects of tunneling on the ground's surface. Construction of the tunnel becomes fundamental and the exploitation of underground space form part of the infrastructure to treat the growing problem of mass rapid transit in urban cities. The method of tunnel construction numerical modeling based on the finite element method is used to evaluate of the ground movement induce tunneling which is an essential matter to predict the settlement through construction and their effects on adjacent buildings. A method of surface settlement prediction is based on field data and results of construction phases numerical modeling. In this study, the prediction of the settlement caused by tunneling by simulation model using numerical method (FEM), with Mohr-Coulomb. This method involves determination of the following characteristics of displacement process: the distribution of displacements, the position of the point of the maximum settlement and the value of the maximum settlement, and strains in the trough. The developed method for calculation of the settlements and he behavior of stress a round tunnel calculates and analysis the settlement during tunnel construction and compared with natural soil through various stages of construction of the tunnel. The results show the behavior of stresses of the native soil and predication of surface settlement through stages of construction of tunnel using the tunnel boring machines(TBM).

Prediction of Surface Settlement Due to Deep Excavation in Indo-Gangetic Plain: A Case Study

Excessive settlement occurred during the installation of collection chamber of sewage pumping station induced minor-to-major damages in the adjacent structures which cautioned the authorities. CSIR-Central Building Research Institute, India, investigated and identified the cause and control further damages to the adjacent structures due to excavation construction. Initial study revealed that excessive settlement occurred due to dewatering carried out after the installation of collection chamber by well sinking method. The presence of soft soil and high water table caused soil movement towards the collection chamber, leading to severe settlement issues. This necessitated a proper study before carrying out further excavation of the adjacent inlet and screen chambers. The evaluations for the remaining two chambers have been carried out using numerical analysis by finite element method and supplemented by comparing with existing analytical approaches and field values. Based on this study, a robust as well as economical shoring scheme is suggested to cater for minimal damage to the nearby buildings.

Prediction of Surface Settlement with Ultra-shallow-burial and Large Rectangular Cross-section Urban Underpass

Based on the actual measured surface settlement of two super-shallow buried large rectangular-section urban underpass, a settlement fitting function is established. The superposition curve used the reduction of settlement trough. By comparing the results of fitting analysis with Peck formula result, settlement characteristics and simple prediction method for super-shallow and large rectangular section urban underpass are proposed, including: 1) The settlement trough is a superposition of three normal distribution curves, with the maximum surface settlement appeared above the central line of each single passage; 2) The depth and width of the middle passage settlement trough should be uniformly reduced. The reduction coefficient is calculated based on the ratio of the middle passage width to the side passage; 3) The loss rate of the side passage is 0.7%–1.0%, while it is 0.4%–0.6% for the middle passage, 4) If the underpass is excavated in staggered sequence, the peck formula can be used to calculate the surface settlement. The surface settlement of a single passage is calculated firstly, and then the surface settlement of three passages is superimposed to obtain the final settlement.

Groundwater-related aspects during the development of deep excavations below the water table: A short review

The expected growth of urban areas requires the construction of underground infrastructures, especially for improving transportation and mobility. These new infrastructures are commonly constructed below the water table because they must be deeper than previous underground structures. In addition, many urban areas are located near surface water bodies (i.e., seas, rivers and/or lakes) that induce a shallow water table. The “cut and cover” method combined with dewatering wells is a frequently used procedure under these conditions for the construction of underground infrastructures. The main concerns of this procedure are related to the stability of the excavation bottom, the behavior of the retaining walls and/or the impacts induced by the dewatering actions. These issues must be evaluated, and new solutions must be proposed to improve its weak points. This paper compiles the main publications focused on the construction of underground infrastructures below the water table and in urban areas by using the cut and cover method combined with pumping. This review reveals that, despite many published studies, more research is needed to address some relevant issues such as: (1) the mitigation of dewatering impacts by using artificial recharge, (2) the adaptation of methods for characterizing retaining walls to be used under heterogeneous conditions, (3) the improvement of the prediction of surface settlements produced by pumping, and (4) the consideration of non-Darcy flows in the design of dewatering systems.

사질토 지반의 비개착공법 시공시 강관압입에 따른 지표침하량 예측식 제안

비개착공법은 주로 도심지역에 적용되는데, 도심지 특성상 토피고가 낮아 터널 굴착시 상부지반에 작용하는 하중이 활동면을 따라 취성파괴로 발생할 가능성이 높다. 따라서 비개착공법 적용시 상부지표면의 변위를 최소화하기 위하여 강관을 압입하여 보강을 실시하고 그 내부를 굴착하게 되는데, 이때 지반과 강관의 마찰력 및 과굴착 등의 이유로 상부지반의 지표침하는 불가피하게 발생하게 된다. 따라서 비개착공법시 강관을 순차적으로 압입할 경우 발생하는 지표침하량을 예측하고자 본 연구에서는 사질토 지반 내 지하수위 영향이 없는 현장을 중심으로 강관 압입에 따른 지표침하 경향분석 및 수치해석을 수행하였으며, 지표침하 예측식인 Gauss분포곡선을 이용하여 지반거동에 적합한 예측식을 도출하고 검증하였다.

A new dynamic prediction method for surface subsidence based on numerical model parameter sensitivity

Surface subsidence is a widespread problem frequently caused by underground mining. Accurate surface subsidence prediction is particularly important for protecting buildings and structures above the goaf. Because mining is a dynamic process, surface dynamic movement and deformation can significantly affect buildings and structures. However, dynamic predictions are often highly inaccurate because of the complex nature of dynamic surface movement and deformation. To address this problem, we performed numerical simulations to assess the sensibility of geomechanical parameters to surface movement values. Our results show that: 1) Sensitive factors of surface movement extremum gradually shift from stiffness parameters to strength parameters with increased mining degree; and 2) the sensitivity of the evaluation indicators to the geomechanical parameters is related to the proportion of plastic zones in the mining-affected area. We propose a new dynamic prediction method of surface subsidence and verify the method with a case study from the Yanzhou mine in China. It is proofed that the new method can greatly improve the prediction accuracy of dynamic surface subsidence. The research results are significant for accurately predicting dynamic surface subsidence, protecting ground buildings and structures while promoting sustainable development of mine areas.

Techniques for Assessing and Mitigating Longwall Subsidence Effects on Interstate Highways

Surface subsidence induced by underground coal mining activities, especially longwall mining operations, can cause various problems to interstate highways ranging from structural integrity, drivability to safety. Accurate subsidence prediction, correct influence assessments, and effective mitigation measures are the keys to ensure the safety of highway traffic. The surface subsidence prediction program, called comprehensive and integrated subsidence prediction model (CISPM), was developed based on the principle of influence function method and has been validated with a large number of subsidence measurements. In this paper, the techniques to use the predicted final surface movements and deformations for assessing their influence on the integrity and functionality of highway structures (e.g., road surface pavements, concrete slabs, transverse joints, etc.), vehicle dynamics, comfort level, and drivability are presented. A number of mitigation measures to protect the highway structures and to ensure traffic safety are proposed along with an application case.

Numerical Simulation and Analysis of Surface and Surrounding Rock Failure in Deep High-Dip Coal Seam Mining

With the continuous reduction of coal resources, mining conditions become more and more complex, showing a trend of deep and large dip. There are two main problems in the mining of high dip seam: on the one hand, the roof caving characteristics of high dip seam mining are more complex, and the solution of this problem is helpful to formulate a reasonable and effective support scheme for the roof in the production process of coal mine; on the other hand, the characteristics of surface subsidence caused by mining of high dip seam, which is related to the prediction and prediction of surface subsidence. Prevention and cure. Based on this, firstly, according to the knowledge of elasticity mechanics, the mining dynamic model of high dip coal seam is established; secondly, the geological model of high dip coal seam is established by using the simulation numerical software FLAC3D, and the excavation process is simulated; finally, the excavation of the working face with 40 m and 14 m coal pillars is simulated by FLAC3D. The results show that the mining of high dip coal seam will cause a large amount of surface subsidence, which will seriously affect the surrounding rock by stress concentration. After setting 40 m and 14 m coal pillars, the serious problems of surface subsidence and surrounding rock destruction caused by mining can be effectively reduced.

Analysis of the Additional Stress and Ground Settlement Induced by the Construction of Double-O-Tube Shield Tunnels in Sandy Soils

Double-O-tube shield tunneling has attracted increasing attention because it offers cost-efficiency in underground construction. Prediction of ground surface settlement and the variety of additional stresses induced by shield construction is crucial to underground construction in metropolises since excessive settlement could trigger potential damage to the surrounding environment. The additional stresses induced by the propulsion of double-O-tube shields are calculated by means of the Mindlin’s equations of elasticity. The characteristics of additional stresses are analyzed with compound Gauss-Legendre integral arithmetic, and the frontal additional thrust, the lateral friction, and the ground loss are taken into account. Subsequently, based on field measurements, the maximum settlement coefficient and width of the settlement trough coefficient of the typical Peck formula are modified. The predictive curve of the Peck formula is closer to the engineering measured data than that of the typical formula. The cut-off functions of ground surface settlement caused by double-O-tube tunnel shield construction are proposed and can predict the shape of ground surface settlement, such as single peak or double peak. The correctness of the proposed functions is verified based on an engineering project.

Breakage law and fractal characteristics of broken coal and rock masses with different mixing ratios during compaction

AbstractBroken coal and rock masses are the major part of the goaf. The compaction characteristics of coal and rock masses and the breakage law of whose particles during compaction exert an important influence on various aspects including control of strata motion, prediction of surface subsidence, and backfill mining. In this paper, the triaxial compaction experiment on broken coal‐rock masses with different mixing ratios was carried out. The test results showed that with the increase of stresses, the strain of coal‐rock masses gradually rose while the porosity, bulking factor, and degree of compaction gradually declined. During the compaction of coal‐rock masses, the fitting curves of the strain, porosity, bulking factor, and degree of compaction with stresses of coal samples all appeared as a cubic function of stresses. The breakage behavior of coal particles underwent three stages: structure re‐arrangement and breakage of particles, particle breakage, and compression‐induced deformation of particles. With increasing stress, the crushing amount of particles gradually grew while the increase rate of the crushed particles gradually decreased and the larger the particle strength was, the lower the increase rate of the crushing amount. Additionally, in the compaction process of samples, particle breakage mainly appeared before the stress reached to 8 MPa while the coal and rock particles were hardly crushed after the stress was larger than 8 MPa. With increasing stresses, the particle size gradation of samples gradually became reasonable and the lower the particle strength of samples was, the more reasonable the particle size gradation of compacted samples. The particle size gradation of various compacted and crushed samples showed a favorable fractal characteristic. In the stage with a low stress, the value of fractal dimension D rapidly grew and the fractal dimensions D of various samples tended to be stabilized after the stress reached to a high level.

Surface subsidence prediction method of backfill-strip mining in coal mining

Intensive and massive coal mining causes a series of geological hazards and environmental problems, especially surface subsidence. In recent years, backfill-strip mining has been applied to control mining subsidence in order to realize sustainable development of the mining environment. To accurately predict the surface subsidence of backfill-strip mining, a prediction method of subsidence superposition of backfill-strip mining is proposed on the basis of the traditional probability integral method prediction model. In analyzing the distribution of the actual subsidence space, the surface subsidence problem of backfill-strip mining can be regarded as the superposition of surface subsidence caused by backfill mining and strip mining. Then, the appropriate prediction parameters will be chosen, and the surface subsidence caused by the backfill mining and strip mining will be predicted separately. The surface subsidence values of the backfill-strip mining are equal to the superposition subsidence values predicted by the backfill mining and strip mining prediction method at the same surface location. A similar material model and a numerical simulation model have been built to verify the feasibility and accuracy of the superposition prediction method. The comparison results of the surface subsidence values show that the superposition surface subsidence prediction method is reasonable. The average relative error of this superposition prediction method is less than 6.7%, and its accuracy is 3.9%~11.4% higher than that of the conventional prediction method. The superposition prediction method can satisfy the precision requirement of engineering applications. This study provides a scientific technical reference for safe mining engineering design and surface disaster protection for backfill-strip mining.

Model tests on longitudinal surface settlement caused by shield tunnelling in sandy soil

The prediction of longitudinal surface settlement caused by shield tunnel construction is a concerning problem. However, despite the increasing concern on it, most existing prediction methods either assume that surface settlement is evenly distributed over the longitudinal direction of the tunnel or the soil affected by tunneling is in a homogeneous, incompressible or undrained state, which is not true in reality. This paper describes results from a series of model tests (conducted at 1g) carried out in sandy soil. In these tests, the effects of tunnel depth and ground volume loss on the longitudinal surface settlement caused by tunnel construction are demonstrated. Based on the Gaussian curve, an equation is developed to predict the distribution of the final longitudinal surface settlement caused by tunnelling.