Ground Surface Movements Research Articles

Experimental Study on the Law of the Ground Surface Movement on the Old Goaf in Different Mining Conditions

The formation process of goaf was dynamically simulated by similar material simulation esperiment. After mining coal was finished and the goaf was basically stable, deformation regularity of surface migrating was studied under gradual loading in different lacation of goaf . The results show: the residual deformation caused by load arranged on both sides of goaf is bigger than that caused by load arranged in the central of goaf. And the maximum values of residual deformation occur on both sides of goaf. The different mining conditions, load location and size will affect the residual deformation. In single mining conditions, a larger load in the both sides of goaf ,the greater the residual deformation.

A theoretical study on ground movement prediction for braced excavation in soft clay

Braced excavation in urban areas requires control of ground movements as well as wall deflection. Previously interpolation from empirical database or numerical analysis by finite element method is used for estimation of ground settlement. But these methods are relatively complex and sometimes important assumptions are invalid at different situations. A design approach for calculating wall deflection and ground settlement is proposed by Bolton and Osman (2006) assuming the plastic deformation mechanism. Here, in this paper this design method is extended by presenting displacement profiles at different zones of the mechanism with different mathematical functions on the basis of ground settlement profile suggested by Peck (1969) and reported case study of Kolkata Metro Excavation (Som, 1991). From this deformation function incremental shear strain is calculated and average shear strain mobilized in each zone is expressed in term of maximum deflection. The conventional hyperbolic stress strain relationship is used to relate mobilized shear stress and shear strain. Finally, the total loss of potential energy is equated with the virtual work done by the soil within the deformed zone in order to develop an equation which may serve as a design tool for calculating ground surface movement and wall deflection at different stages of excavation at different depth.

Repeated absolute gravity measurements for monitoring slow intraplate vertical deformation in western Europe

[1] In continental plate interiors, ground surface movements are at the limit of the noise level and close to or below the accuracy of current geodetic techniques. Absolute gravity measurements are valuable to quantify slow vertical movements, as this instrument is drift free and, unlike GPS, independent of the terrestrial reference frame. Repeated absolute gravity (AG) measurements have been performed in Oostende (Belgian coastline) and at eight stations along a southwest-northeast profile across the Belgian Ardennes and the Roer Valley Graben (Germany), in order to estimate the tectonic deformation in the area. The AG measurements, repeated once or twice a year, can resolve elusive gravity changes with a precision better than 3.7 nm/s2/yr (95% confidence interval) after 11 years, even in difficult conditions. After 8–15 years (depending on the station), we find that the gravity rates of change lie in the [−3.1, 8.1] nm/s2/yr interval and result from a combination of anthropogenic, climatic, tectonic, and glacial isostatic adjustment (GIA) effects. After correcting for the GIA, the inferred gravity rates and consequently, the vertical land movements, reduce to zero within the uncertainty level at all stations except Jülich (because of man-induced subsidence) and Sohier (possibly, an artifact because of the shortness of the time series at that station).

A New Method of Equivalent Material Model Deformation Observation

Equivalent Material Model is a staple method that can be used to imitate the strata and the ground surface movement which caused by human's underground activities, such as coal resources extraction. The precision of indoor imitations are mainly decided by ways of models' deformation observation. This paper proposes a new method of measuring models after analyzing the status of deformation observation of equivalent material models. In this paper, the industrial measuring system is used to measure deformations of the model. The system includes two main parts: photographic surveying of industry instruments and structure lighting scanning devices. The first part is used to get the coordinates of the target points which are set on the model; the second one is used to scan the model surface for catching the cracks on the model surface. Due to the high accuracy of photographic surveying of industry method, it can meet the need of monitoring imperceptible movements of target points; also the structure lighting scanning has a high precision on scanning the model surface, which can get the very thick points cloud of the model surface. The system is originally used for reverse engineering, and it scarcely used for Equivalent material model until our research used, so there is no mature method on data management. This paper researches the special data procession method for the model, and results show that methods in the paper are suit for the industrial measuring system.

응력 -간극수압 연계해석을 이용한 흙막이 굴착시 지하수저하에 따른 지반침하에 관한 연구

본 연구에서는 흙막이 굴착 공사시 지하수저하에 의한 주변 지반의 공학적 거동에 관한 수치해석 연구내용을 다루었다. 먼저 2차원 간극수압-응력 연계해석을 통하여 굴착공사가 지반침하 거동에 미지는 영향을 알아보았으며 그 결과를 토대로 벽체 수평변형, 벽체배변 변형, 소성변형률 분포, 유효응력분포 및 버팀보 축력분포 등을 분석을 수행하였다. 한편 다양한 지층조건과 초기 지하수위 조건에 대한 매개변수 연구를 통하여 주변지반 및 버팀보의 거동을 분석하였으며 해석 결과를 토대로 특정조건의 최대 지반변형범위를 제안하였다. This paper presents the results of a numerical investigation on the behavior of earth retaining wall system with emphasis on the groundwater lowering. Using the 2D stress-pore pressure coupled analysis, the effects of ground excavation and groundwater interaction were examined using wall horizontal deformation, ground surface movement, plastic strain pattern, effective stress distribution and axial stress of strut. In addition, based on the results from a parametric study on a wide range of soil profile and initial ground water table level, the ranges of wall displacement and ground deformation were suggested quantitatively.

Dynamic Response of Pile Groups under Vertical Forces in Saturated Soil

Based on Biot’s wave propagation equation and boundary conditions, this paper builds up pile group and soil system used for calculation in 3 dimension models, though mass conservative and motion equation. The results of ground surface movement are obtained under the effect of vertical dynamic force though Newmark direct integration. Compared with the measured results, the numerical outcomes conform accurately. The calculating results show that vibration of ground surface can be affected by several parameters such as soils’ possion ratio, permeability coefficient, different types of pile groups and so on. Different factors have different effects on ground’s surface vibration in both far field and near field.

Estimation of ground deformation caused by the earthquake (M7.2) in Japan, 2008, from the geomorphic image analysis of high resolution LiDAR DEMs

In this study, a new method for quantitative and efficient measurement for the ground surface movement was developed. The feature of this technique is to identify geomorphic characteristics by image matching analysis, using the intelligent images made from high resolution DEM(Digital Elevation Model). This method is useful to extract the small ground displacement where the surface shape was not intensely deformed.

Ground movement prediction for tunnels using simplified procedure

Stochastic medium theory is an effective method to predict tunneling-induced ground surface movement. However, the calculation formula of this theory is a complex double integral and the limit of integration is difficult to obtain when the cross section of tunnel is non-circular. In this paper, the stochastic medium theory is simplified, and the simplified procedure is proposed to predict the ground surface movement. In order to evaluate the validity of the simplified procedure, the numerical results using the stochastic medium theory are compared with those using the simplified procedure. The comparisons show that the present results by the simplified method agree well with the results by the stochastic medium theory except for very shallow tunnel, which means that the simplified method is an effective technique for predicting ground surface movement.

Artificial neural network application for the prediction of ground surface movements induced by shield tunnelling

This paper presents a methodology to correlate ground surface movements and tunnel boring machine (TBM) operation parameters. Two approaches are proposed and evaluated based on a case study of a shallow tunnel in a dense urban area. The first approach is based on a least square approximation and the second one uses an artificial neural network model. Data analysed were selected from the excavation of the subway line B tunnel in Toulouse, France, which was performed mainly by a shield TBM. Ground movements measured on the 4.7 km long contract 2 are reproduced with reasonable agreement by each of the two approaches. The amount of data (in particular for TBM operation parameters), the rather small amplitude of measured movements (a few millimetres), and the accuracy of these measurements (designed for routine construction management) make it necessary to create a pre-processing technique for the data, and a step-by-step improvement of approaches used. An elimination procedure is proposed to identify the most influential operation parameters and a sensitivity analysis shows their respective effect on ground movements.

Three-dimensional ground displacements from static pipe bursting in stiff clay

Three-dimensional ground surface displacements from 20 m long static pipe-bursting experiments are reported. These experiments were conducted with firm-to-stiff clay backfill in a trench with very stiff clay sidewalls at three different burial depths. Multiple digital cameras and image analysis were used to quantify the surface response as the expander progressed through the original pipe. The experiments quantified the upward surface movement as the expander approached, the effect of burial depth on maximum uplift, and the final amount of uplift after it decreased to a residual displacement. The experiments also quantified the axially forward ground surface movement as the expander approached, reaching maximum just ahead of the expander, and decreasing to almost zero after the expander had passed by. Lateral movements of the ground surface away from the centreline are also reported, which were essentially zero at the centre line, increasing to a maximum and then decreasing with distance from the centreline. The three different burial depths produced in effect the same width of vertical surface response with the displacements contained within 1.5 m on either side of the centreline, suggesting that the very stiff clay trench walls had a dominant influence on the measured displacements.

Fully Coupled Numerical Modelling of Ground Surface Uplift in Steam Injection

Abstract In enhanced oil recovery, steam injection involves high stresses, pressures, temperatures and volume changes. Traditional reservoir simulation fails to predict associated transient ground surface movements because it does not consider coupled geomechanical effects. We present a fully-coupled, thermal half-space model using a hybrid DDFEM method, in which a simultaneous finite element method (FEM) solution is adopted for the reservoir and the surrounding thermally affected zone, and a displacement discontinuity (DD) method used for the elastic, non-thermal zone. This approach provides transient ground surface movements in a natural manner. Introduction Enhanced oil recovery (EOR) methods involving high pressures and steam injection (steamflooding, cyclic steam stimulation, steam-assisted gravity drainage) are accompanied by large volume changes in the reservoir horizon. Ground movements in excess of 300 mm heave or subsidence are registered during injection and production cycles. Reservoir simulation cannot address this phenomena without due consideration of geomechanical effects. The earliest theory to account for coupled pore fluid behaviour and soil deformation was the Terzaghi one-dimensional consolidation theory, still used in soil mechanics. Since Biot's theory of consolidation(1) was introduced to petroleum engineering by Geertsma(2) with the coined term "poroelasticity,?? coupled analysis of petroleum geomechanics effects has been widely advocated(3-5). Coupled reservoir simulation can be carried out in a loosely coupled fashion(6, 7) or with a tightly coupled scheme(8-10), and comparisons of different coupling techniques can be found (11, 12). In reservoir simulation, a coupled analysis demands simultaneous solution of changes in (p,T) and fluid flow as well as stress and strain. Computing challenges persist in large-scale 3D applications to real cases where there are a huge number of equations to solve iteratively; e.g. thermo-poro-elasto-plastic analyses involving several simultaneous diffusion processes (Darcy, Fourier, Fick). In regions of large pressure, temperature, concentration or stress gradients, accurate solution requires small-scale discretization. If the problem has strong non-linearity, such as changes in permeability, compressibility, or other properties arising from changes in pressure and effective stress, the computational effort increases by several orders of magnitude because multiple iteration loops are needed. These issues mean that accurate analysis of realistic complex 3D problems is challenging, and will so remain as we seek to solve larger and larger coupled problems involving non-linear responses.

Thermal reservoir modeling in petroleum geomechanics

AbstractThermal oil recovery processes involve high pressures and temperatures, leading to large volume changes and induced stresses. These cannot be handled by traditional reservoir simulation because it does not consider coupled geomechanics effects. In this paper we present a fully coupled, thermal half‐space model using a hybrid DDFEM method. A finite element method (FEM) solution is adopted for the reservoir and the surrounding thermally affected zone, and a displacement discontinuity method is used for the surrounding elastic, non‐thermal zone. This approach analyzes stress, pressure, temperature and volume change in the reservoir; it also provides stresses and displacements around the reservoir (including transient ground surface movements) in a natural manner without introducing extra spatial discretization outside the FEM zone. To overcome spurious spatial temperature oscillations in the convection‐dominated thermal advection–diffusion problem, we place the transient problem into an advection–diffusion–reaction problem framework, which is then efficiently addressed by a stabilized finite element approach, the subgrid‐scale/gradient subgrid‐scale method. Copyright © 2008 John Wiley & Sons, Ltd.

Groundwater flow modeling for effective implementation of landslide stability enhancement measures

This paper deals with groundwater hydrology at a prominent fracture zone landslide slope (Nuta–Yone landslides) in Japan with an objective to explore an efficient method for the application of landslide stability enhancement measures. The correlation analyses between the hydrological parameters and ground surface movement data at this landslide resulted in low correlation values indicating that the geological formation of the area is extremely complex. For the purpose of understanding the groundwater flow behavior in the landslide area, a three-dimensional transient groundwater flow model was prepared for a part of the landslide slope, where the levels of effectiveness of applied landslide stability enhancement measures (in the form of multilayered deep horizontal drains) are different, and was calibrated against the measured water surface elevations at different piezometer locations. The parameter distributions in the calibrated model and the general directions of the groundwater flow in terms of flow vectors and the results of particle tracking at the model site were interpreted to understand the reasons for variations in effectiveness of existing landslide stability enhancement measures and to find potentially better locations for the implementation of future landslide stability enhancement measures. From the modeling results, it was also understood that groundwater flow model can be effectively used in better planning and locating the landslide stability enhancement measures.

Three-Dimensional Responses Observed in an Internally Braced Excavation in Soft Clay

Several three-dimensional effects were observed in the performance monitoring data collected during excavation for the Ford Engineering Design Center in Evanston, Illinois. The elevations of the soil around the excavation varied and the excavator removed the soil in a nonuniform excavation process, both of which contributed to the observed three-dimensional (3D) effects. This paper describes the excavation support system and subsurface conditions at the site, summarizes the construction procedures, and presents the lateral soil movements measured by inclinometers, ground-surface movements measured by an automated total station, tilt of components of an adjacent structure, and forces in internal braces. These responses are compared with expected responses from current design methods. The 3D nature of the excavation resulted in smaller movements on the side of the excavation, where the retained soil was lowest, an unexpected pattern of axial strut loads and very slight damage to an exterior wall that paralleled one of the excavation walls.

Forecasting vertical ground surface movement from shrinking/swelling soils with artificial neural networks

AbstractArtificial neural networks (ANNs) are used to estimate vertical ground surface movement when soils expand and contract due to changes in soil moisture content caused by changing climate conditions. Several counterpropagation ANN test cases were investigated to map climate data (i.e. temperature and rainfall) to vertical ground surface movement at field sites in Texas and Australia. Three of the four ANN test cases use a historical time series of climate data to forecast ground surface elevation relative to a specified datum. The fourth ANN test case predicts the rate of ground surface movement, and requires post‐processing of the predicted rates to calculate ground surface elevation relative to a specified datum. The counterpropagation network has demonstrated a successful mapping of temperature and rainfall data to vertical ground surface movement at a field site when it is trained with a subset of data from the same field site (test cases 1 and 2). The results of training an ANN on one field site and testing it on another field site (test cases 3 and 4) demonstrate the ability of the ANN to capture trends in vertical ground surface movement. When compared with the predictions from a physics‐based method (shrink test‐water content method) that requires measurements/estimates of changes in soil water content, the ANN‐based predictions (based on climatic changes) captured the trends in the field measurements of shrinking–swelling soil surface movements equally well. These findings are promising and merit further investigation with data from additional field sites. Copyright © 2007 John Wiley & Sons, Ltd.

Deep excavation-induced ground surface movement characteristics – A numerical investigation

This paper concerns the characterization of deep excavation-induced ground surface movements, using the results of numerical investigation. A calibrated 2D finite element model using the Lade’s double hardening constitutive model for soil was used to form a database of the wall and ground surface movements associated with deep excavation. The results indicated that the cantilever and the lateral bulging excavation stages produce distinctive patterns of ground surface movement profiles, and that final ground surface movement profiles can be constructed by combining the cantilever and the lateral bulging components with a reasonable degree of accuracy. A two-step approach for use in the prediction of ground surface movement profiles is proposed.

Fuzzy genetic programming method for analysis of ground movements due to underground mining

The prediction of ground surface movements is an important problem in rock and soil mechanics in the excavation activities especially the coal and metal mining. Based on results of the statistical analysis of a large amount of measured data in underground excavation engineering, the fuzzy genetic programming method (FGPM) of ground surface movements is given by using the theory of fuzzy probability measures and genetic programming (GP). And genetic programming approach is proposed to determine the parameter of ground surface movements due to underground mining of coal in this paper. Genetic programming is trained by used practical mining induced surface movement data. The agreement of the theoretical results with the field measurements shows that the FGPM is satisfactory and the formulae obtained are valid and thus can be effectively used for predicting the ground surface movements due to underground mining, especially the mining of coal and metal.

Plant community dynamics on the volcano Mount Koma, northern Japan, after the 1996 eruption

A small eruption occurred in the early spring of 1996 on the summit of Mount Koma, northern Japan, 67 years after the 1929 catastrophic eruption. To identify damage on the plant communities and recovery patterns, we established 400 50 × 50 cm permanent plots in four locations along the gradient of the thickness of tephra produced in 1996: non-disturbed (N), weakly disturbed (W), middle disturbed (M), and heavily disturbed (H). Annual monitoring was conducted from 1996 to 2001. Gullies and rills formed in M and H, indicating that the ground surface movements were more intense there. Mean vascular plant species richness increased from H to N, but did not increase from 1996 to 2001 in any location. In an area where tephra thickness was 10 cm, the recovery was mostly conducted by the species that could have survived during the eruption. A shrub,Salix reinii, was the leading species in most sites throughout most years. Large perennial herbs,Polygonum weyrichii, P. sachalinense andMiscanthus sinensis were common in the disturbed areas, in particular in M and H. Those three species develop large underground organs and enlarge clonally, suggesting that the tolerance to ground surface stability is the most important trait for the recovery of those species.Carex oxyandra established not only by vegetative regeneration but also by seedling regeneration. A short forb,Campanula lasiocarpa, could establish only in W by seedling regeneration. Mosses and lichens were predominant in plots in N and W, but less represented and not greatly increasing their cover in M and H up to 2001. We concluded that the community recovery was delayed in all the disturbed areas, mostly due to low seedling establishment. Only a few specific species established by vegetative reproduction. Disturbance gradients such as thickness of tephra and/or ground surface stability have determined plant community structure and development.

The influence of soil anisotropy and K0 on ground surface movements resulting from tunnel excavation

Finite element (FE) analysis is now often used in engineering practice to model tunnel-induced ground surface settlement. For initial stress regimes with a high coefficient of lateral earth pressure at rest, K0, it has been shown by several studies that the transverse settlement trough predicted by two-dimensional (2D) FE analysis is too wide when compared with field data. It has been suggested that 3D effects and/or soil anisotropy could account for this discrepancy. This paper presents a suite of both 2D and 3D FE analyses of tunnel construction in London Clay. Both isotropic and anisotropic non-linear elastic pre-yield models are employed, and it is shown that, even for a high degree of soil anisotropy, the transverse settlement trough remains too shallow. By comparing longitudinal settlement profiles obtained from 3D analyses with field data it is demonstrated that the longitudinal trough extends too far in the longitudinal direction, and that consequently it is difficult to establish steady-state settlement conditions behind the tunnel face. Steady-state conditions were achieved only when applying an unrealistically high degree of anisotropy combined with a low-K0 regime, leading to an unrealistically high volume loss.

The influence of soil anisotropy andK0on ground surface movements resulting from tunnel excavation

Finite element (FE) analysis is now often used in engineering practice to model tunnel-induced ground surface settlement. For initial stress regimes with a high coefficient of lateral earth pressure at rest, K0, it has been shown by several studies that the transverse settlement trough predicted by two-dimensional (2D) FE analysis is too wide when compared with field data. It has been suggested that 3D effects and/or soil anisotropy could account for this discrepancy. This paper presents a suite of both 2D and 3D FE analyses of tunnel construction in London Clay. Both isotropic and anisotropic non-linear elastic pre-yield models are employed, and it is shown that, even for a high degree of soil anisotropy, the transverse settlement trough remains too shallow. By comparing longitudinal settlement profiles obtained from 3D analyses with field data it is demonstrated that the longitudinal trough extends too far in the longitudinal direction, and that consequently it is difficult to establish steady-state settlement conditions behind the tunnel face. Steady-state conditions were achieved only when applying an unrealistically high degree of anisotropy combined with a low-K0 regime, leading to an unrealistically high volume loss.