Overburden Layer Research Articles

Effect of cold CO2 injection on fracture apertures and growth

The injection of cold CO2 is modelled in three dimensions using a two-stage coupled thermoporoelastic model, with the aim of evaluating changes in apertures and potential growth of fractures. Non-isothermal flow is considered within the fractures and the rock matrix, and the two flow domains are coupled through a mass transfer term. The numerical model has been developed using standard finite elements, with spatial discretisation achieved using the Galerkin method, and temporal discretisation using finite differences. A full-scale field case geometric model, based on the Goldeneye depleted hydrocarbon reservoir in the North Sea, is developed and used for simulations. The in situ faults are modelled discretely as discontinuous surfaces in a three-dimensional matrix, including basement, reservoir, caprock and overburden layers. The faults are assumed initially to be low-permeable faults, with the same permeability as the caprock. However, the simulations show that their apertures (and as a result, their permeabilities) vary due to the thermoporoelastic effects caused by the injection of the relatively cold CO2. The change in the fracture apertures is mainly due to thermal effects; the reservoir layer undergoes contractions due to the cooling, significantly increasing fault aperture in the region of the fault within the reservoir, whereas the fault aperture is reduced in regions within the caprock. Propagation of fractures under thermoporoelastic loading is investigated. Results show that the distance to the injection well, as well as spatial orientation of fractures with respect to the injection well, affect aperture evolution and potential growth of fractures. A sensitivity analysis is performed on the parameters affecting the fracture growth: minimum normal stress acting on the fracture plane, dip angle of the fracture, and the contact friction coefficient. It is found that low friction, low normal contact stress, or high in situ shear stress on the fracture surfaces may trigger propagation under combined mode II and III within the reservoir layer, or at the interface of the reservoir and caprock.

Comparative analyses of seismic site conditions and microzonation of the major cities in Gangwon Province, Korea

To determine the seismic site conditions and microzonation of Chuncheon, Wonju and Gangneung cities in the Gangwon Province, Korea, the dispersion curves of Rayleigh waves were derived at 313 sites by the extended spatial autocorrelation (ESPAC) method. Using the shear-wave velocities (Vs) determined from dispersion curves, average depth to the bedrock (Db) and Vs at the top of the bedrock (Vsb), the overburden layer (Vso) and the top 30 m depth layer (Vs30) were determined. The resonance frequencies (fr) were then computed using both Db and Vso. The estimated averages of the three cities were 13 ± 7 m for Db, 472 ± 109 m/s for Vsb, 248 ± 44 m/s for Vso, 411 ± 157 m/s for Vs30 and 5.8 ± 2.8 Hz for fr. Microzonation maps based on the proxy-based Vs30 indicated that the three cities were mainly categorised into National Earthquake Hazards Reduction Program (NEHRP) classes B, C and D, with a minor proportion of A. Although no area was estimated to be in class E using the proxy-based Vs30, the Vs30 values derived from the recorded Rayleigh waves at 13 sites in Gangneung were less than 180 m/s. This indicates a greater vulnerability to seismic amplification during large earthquakes in this city, which had the smallest Vso, Vs30 and fr, and the greatest Db of the three cities. Microzonation maps, together with information for fr, can be effectively used for seismic risk assessments, urban planning, and disaster management.

A Modified Newmark Methodology for Permanent Deformation Analysis of Rock-Fill Dams

Newmark sliding block approach has been extensively studied by many researchers in the past decades. Significant progress has been made to alleviate its deficiencies and overcome its simplifying assumptions, but some aspects such as the cyclic shear strength and time history vertical acceleration in the Newmark sliding displacement analysis are seldom considered strictly. In the presented research, a modified Newmark methodology for sliding deformation analysis of rock-fill dams subjected to strong earthquake is proposed. In order to make the seismic safety evaluation of dams more realistic, the influence of cyclic shear strength (earthquake-induced reduction of shear strength) and time history vertical acceleration obtained from the dynamic response analysis on the critical acceleration and accumulative sliding displacement of the flexible sliding body is considered. Detailed comparison between the proposed method and existing methods is performed via the analysis of two typical dams, that is, a virtual rock-fill dam with a height of 100 m which is assumed to be situated on rock formation and a real core rock-fill dam with a height of 150 m built on deep overburden layers. It is demonstrated that the cyclic shear strength and time history vertical acceleration within flexible sliding body, as highlighted in the proposed method, have significant effect on the seismic safety evaluation, critical acceleration, and accumulation of sliding deformation of rock-fill dams subjected to strong earthquake loading. The existing approaches tend to provide unconservative evaluation on the consequences of earthquakes on rock-fill dams.

Subsidence prediction method of solid backfilling mining with different filling ratios under thick unconsolidated layers

Solid backfill mining for coal pillar recovery in industrial squares has to ensure that the mine infrastructure, such as the shafts and substations, is not degraded or has its utility impaired by that mining. At the same time, it is important to recover as much coal as possible. As a result, it is necessary to predict mining subsidence during solid backfilling mining of coal pillars in industrial squares and to optimize the design of the working faces. At the Baishan coal mine in Anhiu province, China, there are thick layers of unconsolidated overburden above the coal seam so it is not appropriate to use the surface subsidence prediction method of equivalent mining height to predict subsidence during the mining of the coal pillars there. In order to find a reasonable coal pillar recovery scheme for the Baishan mine, a numerical simulation method is used to determine the relationships between the compression ratio of the backfilling material and the surface subsidence prediction parameters. Research was done to determine the appropriate parameters, and based on the final prediction parameters and taking the mandated protection standards for buildings and structures into account, surface subsidence is predicted and a backfill mining scheme for pillar recovery is proposed. The results show that of the six mining schemes considered, scheme 5 is the best scheme for coal pillar recovery in the industrial square at the Baishan mine. The research results are significant for similar mines with thick unconsolidated overburden anywhere in the world.

Response of a Circular Tunnel Through Rock to a Harmonic Rayleigh Wave

A factor that combines tunnel depth and incident wavelength has been numerically determined to dominate the seismic responses of a tunnel in rocks that are subjected to harmonic P- and S-waves. This study applies the dynamic finite element method to investigate the seismic response of shallow overburden tunnels. Seismically induced stress increments in the lining of a circular tunnel that is subjected to an incident harmonic R-wave are examined. The determination of R-wave considers the dominant frequency of acceleration history of the 1999 Chi–Chi earthquake measured near the site with damage to two case tunnels at specifically shallow depth. An analysis reveals that the normalized seismically induced axial, shear and flexural stress increments in the lining of a tunnel reach their respective peaks at the depth h/λ = 0.15, where the ground motion that is generated by an incident of R-wave has its maximum. The tunnel radius has a stronger effect on seismically induced stress increments than does tunnel depth. A greater tunnel radius yields higher normalized seismically induced axial stress increments and lower normalized seismically induced shear and flexural stress increments. The inertia of the thin overburden layer above the tunnel impedes the propagation of the wave and affects the motion of the ground around the tunnel. With an extremely shallow overburden, such an effect can change the envelope of the normalized seismically induced stress increments from one with a symmetric four-petal pattern into one with a non-symmetric three-petal pattern. The simulated results may partially elucidate the spatial distributions of cracks that were observed in the lining of the case tunnels.

An empirical relationship between seismic bedrock depth and fundamental frequency for Değirmendere (Kocaeli-Turkey)

Sediments’ thickness is one of the important parameters in seismic hazard assessment. This study aims to establish a new empirical relationship to determine the overburden layer thickness on seismic bedrock by using a relationship between the fundamental frequencies obtained from microtremor measurements and seismic bedrock depth obtained from microgravity measurements and subsequently produce an approximate seismic bedrock depth distribution map for the study area. In this context, ambient noise analyses were performed to estimate the fundamental frequency of the ground. Within this scope, noise measurements at 43 points were established in the study area. Determined fundamental frequencies and seismic bedrock depths obtained by microgravity measurements were iteratively processed to calculate the best-fitting exponential function for the empirical depth–frequency relation. This relation was established as $$m = 338.2 \cdot f_{0}^{ - 0.6558}$$ (m is seismic bedrock depth, f 0 is fundamental frequency) for the study area.

New deformation back analysis method for the creep model parameters using finite element nonlinear method

Creep deformation of rockfill and overburden affect anti-seepage systems, such as face slabs, toe slabs, and peripheral joints, which may cause structural damage, particularly in a high concrete-faced rockfill dam (CFRD) on a deep overburden layer. The deformation mechanism of rockfills is complex. It is difficult to determine the creep deformation characteristics completely with creep test. Back analysis based on measured data inversion is an effective approach to study the long-term deformation characteristics of CFRD. In this paper, a new deformation back analysis method called MPSO-BP, which integrates a modified particle swarm optimization algorithm and neural network simulator, is presented to reverse the creep model parameters of Jiudianxia CFRD based on the plate load test, pressure test, and large-scale triaxial test. The creep model parameters of rockfill and overburden are applied to analyze and forecast the long-term deformation characteristics of the CFRD by using 3D nonlinear finite element numerical analysis method. Results show that the calculated creep deformations are agreed with the monitoring data. The back analysis method and the inversion parameters are demonstrated to be reasonable. The deformation of the CFRD tends to stabilize after the dam reservoir reaches its tenth year of operation.

Dynamic geotechnical properties evaluation of a candidate nuclear power plant site (NPP): P- and S-waves seismic refraction technique, North Western Coast, Egypt

Determination of the dynamic geotechnical properties and Vs30 of soil and rocks from seismic wave velocities serves as essential inputs for a foundation design cognizant of seismic site response and rock strength. This study evaluates a site which was suggested for a Nuclear Power Plant (NPP) in El-Dabaa area, north western coast of Egypt. On the near subsurface geology is made up of a thick succession of limestone overlain by a thin layer of soft soil. Assessment of geotechnical materials and Vs30 of the near sub-surface lithological layers are required for design of the foundation of critical structures like turbo-generator and reactor buildings. Interpretation of ninety one shallow P-waves and S-waves seismic refraction profiles distributed within the study area in conjunction with data of 76 boreholes were undertaken to delineate the dynamic properties of shallow soil for construction NPP. The velocity of the P- and S-waves were acquired and interpreted using SeisImager Software Package, then the results were used to build a velocity-depth model to estimate the depth to the bedrock and the thicknesses of overburden layers. This model was verified using boreholes data dissected the seismic profiles to improve the final velocity depth model. The depth to bedrock was determined from both shallow seismic refraction profiles and boreholes. Vs30, elastic moduli and dynamic geotechnical parameters were calculated and the site was classified as a National Earthquake Hazard Reduction Program (NEHRP) class “B”. The values of seismic velocities, the engineering consolidations, and the strength parameters showed that the bedrock in the study area is characterized by more competent rock quality.

Overburden 4D time shifts — Indicating undrained areas and fault transmissibility in the reservoir

Production-induced geomechanical stress changes cause velocity changes in the overburden that might be detected as 4D seismic time shifts. The strength of the velocity changes depends on the degree of pressure changes and the elastic properties of the reservoir and overburden layers. Even small velocity changes (less than 1%) might accumulate into detectable seismic time shifts at the top reservoir, since the overburden thickness typically ranges from one to several kilometers. Reservoir pressure changes inducing seismic time shifts are observed in the overburden of the Snorre, Heidrun, and Statfjord fields, all located on the Norwegian Continental Shelf. The strong correlation between overburden time shifts, geomechanics, and reservoir pressure changes is used to indicate undrained areas and transmissibility across faults, which is useful information for increased oil recovery, well planning, and reservoir model updating. 4D geomechanical models are built with input from simulated reservoir pressures. Geomechanical strain and velocity changes are linked through a “dilation” factor, R. The Snorre, Heidrun, and Statfjord fields indicate an average R value of about 15 for the overburden, when combining modeled vertical strain with observed seismic time shifts. However, this study also shows strong vertical variation in R, implying that R might be layer dependent. For the Statfjord Field, seabed subsidence measurements from gravity and GPS monitoring are used to calibrate the geomechanical model. The Snorre Field results show that both reservoir pressure depletion and pressure buildup can be identified by the use of overburden time shifts. The properties of the reservoir formations and surrounding layers of the investigated fields are typical for many fields on the Norwegian Continental Shelf. This implies that pressure-induced time shifts might be expected for many producing fields, not only chalk or high-pressure, high-temperature reservoirs but also sandstone reservoirs close to hydrostatic pressure.

Applying full-azimuth angle domain imaging to study carbonate reefs at great depths

The main goal of the seismic surveys conducted in the target area in Kazakhstan was to image and detect a major Devonian carbonate barrier reef and to characterize the density and orientation of its main fracture zones. This area is unique in that the carbonate layers occur at great depths, from 5700 to 8500 m, with a complex structure of overburden layers of interbedded clay, sandstone, salt and others (Table 1). These different lithology plays and morphology rocks create strong vertical and lateral velocity variations, resulting in a complex seismic wave phenomenon. In addition, the target carbonate structures contain heterogeneous objects and require high-quality processing of the recorded data. Under such conditions, it is crucial to use full-azimuth, long-offset and dense (high fold) acquisition patterns. Advanced processing sequence tools and high-end depth migrations are required to handle both strong heterogeneity and azimuthal anisotropy effects. Traditional Kirchhoff migrations, even the most accurate ones (wavefront reconstruction, beam), have not been able to provide the required image quality and level of detail required at the target zones (Figure 1). Conventional Kirchhoff migrations generate surface offset-azimuth/offset domain common image gathers (CIG). In this particularly complex area, the correlation between the surface offset-azimuths and the actual, in situ, subsurface slowness-azimuths (azimuth of the incidence/reflected ray pairs at the image points) is relatively poor, leading to significant errors in the estimation of fracture orientation. Additionally, Kirchhoff migrations do not account for multi-pathing (multi-wave path solutions between image points and surface source/receiver locations), which is essential when imaging in areas involving complex wave phenomena. Kirchhoff beam migrations map surface beams with given directions backward to the subsurface. Since they account for the multi-pathing, they provide better results. However, they normally generate the same type of surface offset-azimuth/offset CIGs and therefore cannot be accurately used for azimuthal studies. They also cannot ensure sufficient subsurface illumination, especially at the complex target subsurface regions.

Methodological basis for calculating parameters of direct dumping flowsheets in open pit mining of gently dipping coal beds

Under discussion are the direct dumping flowsheets applied to remove lower overburden layers at coal series deposits in Kuzbass. The authors present the calculation procedure for the parameters of overburden excavation and re-excavation flowsheets using draglines. It is found how the re-excavation coefficient depends on the place and level of the dragline site. The recommendations on selecting the dragline route in internal dumping are made. The main trends toward expanding the area of application of the direct dumping technology are identified.

The transient impact of the resonant flexible drill string of a sonic drill on rock

Sonic drilling is a fast and efficient method for the undisturbed sampling of soft soils and is widely used in overburden layer drilling such as in soft soil and gravel. This technique can also be used to quickly drill through bedrock using vibration shock technology with rotary drilling, a process that differs from the general vibratory immersed-pipe/pile method. To date, little has been published at home or abroad regarding how to determine the impact of sonic drill bits on rock to rationally design button bits for highly efficient rock penetration. This paper establishes a mathematical model of a sonic drill with a flexible drill string on rock, succeeds in determining a transient solution for flexible drill string vibrations under complex boundary conditions, and systematically studies the influential impulse factors of the sonic resonant flexible drill string on rock by a button bit. As the bedrock stiffness and order of the resonance increase, the magnitude of the impact peak increases, and the impact duration becomes shorter. As the drilling hole is extended, the drill string becomes longer, and the largest impulse obviously decreases. In addition, the damping increase is approximately proportional to the attenuation inhibition effect on the impact force. Through systematic research on the modeling and determination of the impact of the sonic drilling process, the design theory of sonic drilling can continue to be improved.

Factors that affect coseismic folds in an overburden layer

Coseismic folds induced by blind thrust faults have been observed in many earthquake zones, and they have received widespread attention from geologists and geophysicists. Numerous studies have been conducted regarding fold kinematics; however, few have studied fold dynamics quantitatively. In this paper, we establish a conceptual model with a thrust fault zone and tectonic stress load to study the factors that affect coseismic folds and their formation mechanisms using the finite element method. The numerical results show that the fault dip angle is a key factor that controls folding. The greater the dip angle is, the steeper the fold slope. The second most important factor is the overburden thickness. The thicker the overburden is, the more gradual the fold. In this case, folds are difficult to identify in field surveys. Therefore, if a fold can be easily identified with the naked eye, the overburden is likely shallow. The least important factors are the mechanical parameters of the overburden. The larger the Young’s modulus of the overburden is, the smaller the displacement of the fold and the fold slope. Strong horizontal compression and vertical extension in the overburden near the fault zone are the main mechanisms that form coseismic folds.

Seismic stability analysis of subsea tunnels under the effects of seepage and temperature

ABSTRACTThis study used the strength reduction method to analyze the seismic stability of a subsea tunnel under the effects of seepage and temperature. Excess pore water pressure within the rock mass was first eliminated by calculating the consolidation; then, an earthquake wave was applied to begin the dynamic and time-history analysis and to obtain the maximum horizontal displacement of the model boundary. Finally, a temperature field model was established for the thermal analysis of the structure. The temperature of each node of the structure was regarded as a form of outside load applied to the reduction model; both sides of the vertical horizontal displacement of the boundary nodes and gravity were used as inputs for the static analysis when the vertex horizontal displacement reached its maximum value. By continuously decreasing the shear strength parameters, the safety factor of the tunnel structure was determined. The results show that the plastic zone first appeared in a smaller range on both sides of the tunnel arch feet near the lining and vault of both sides. The safety factor decreased with increasing water depth and overburden layer thickness.

Investigation of the Youjiang active fault zone and a preliminary study of its impact on the planned Huaneng Baise Power Plant

Along with the rapid development of the Chinese economy, there is an increasing demand for power consumption in southern China. The China Huaneng Group plans to build the Huaneng Baise Power Plant in the Baise region of Guangxi Province. The plant site is located in Baise City, Tianyang County, and is close to the Youjiang fault zone, which is an active fault zone. To investigate the impact of the active fault zone on the planned power plant, the geographical distribution of the fault zone and its relationship to the plant site should be further clarified. Because the plant site is covered by a Quaternary overburden layer and the Youjiang fault zone is concealed beneath the layer, the geographical relationship between the Youjiang fault zone and the plant site is difficult to determine. This paper reports on a comprehensive investigation using multiple approaches, including drilling, geophysical prospecting and a geological survey. By searching the moniliform spring heads and comparing strata variations and topographic changes between the foot wall and the hanging wall of the active fault zone, the location and trend of the Youjiang active fault zone were determined. The characteristics of this fault zone were further analyzed using high-density resistivity measurements and seismic imaging. Preliminary studies were conducted on the impact of the Youjiang active fault zone on the planned Huaneng Baise Power Plant, which provide an important basis for seismic safety assessment and also a significant reference for a feasibility study of the power plant. This investigation is a part of The Feasibility Study Project of Huaneng Baise Power Plant.

Numerical stress-deformation analysis of cut-off wall in clay-core rockfill dam on thick overburden

The cut-off wall in a clay-core rockfill dam built on a thick overburden layer is subjected to a large compressive pressure under the action of the loads such as the dead weight of both the dam and the overburden layer, the frictional force induced by the differential settlement between the cut-off wall and surrounding soils, and the water pressure. Thus, reduction of the stress of the cut-off wall has become one of the main problems for consideration in engineering design. In this paper, numerical analysis of a core rockfill dam built on a thick overburden layer was conducted and some factors influencing the stress-strain behaviors of the cut-off wall were investigated. The factors include the improvement of the overburden layer, the modeling approach for interfacial contact between the cut-off wall and surrounding soils, the modulus of the cut-off wall concrete, and the connected pattern between the cut-off wall and the clay core. The result shows that improving the overburden layer, selecting plastic concrete with a low modulus and high strength, and optimizing the connection between the cut-off wall and the clay core of the dam are effective measures of reducing the deformations and compressive stresses of the cut-off wall. In addition, both the Goodman element and the mud-layer element are suitable for simulating the interfacial contact between the cut-off wall and surrounding soils.

Microtremor response of the Cheongcheon dam in Korea

Microtremors were analysed using the reference-dependent horizontal spectral (H/H) method and the horizontal-to-vertical spectral ratio (H/V) method to estimate site effects of the Cheongcheon earthen dam in Korea. Seismic vibrations were recorded on the dam’s crest, at the toe of the dam, and in a downstream borehole using three-component accelerometers. The H/H peaks for crest versus toe-of-dam accelerations occurred at 3.1, 6.7 and 13.1 Hz with ratios of 6.9, 11.4 and 8.9, respectively. The H/V peaks for the crest of the dam occurred at 3.0, 7.0 and 13.4 Hz with ratios of 6.7, 7.8 and 5.6, respectively. The peak near 3 Hz may correspond to depth to bedrock, whereas the other peaks at higher frequencies may reflect the geometrical effect of the dam or overtone responses to the thickness of dam fill overlying the clay core. For the toe data, from the H/V spectral ratio method, the basement boundary appeared as double peaks near 8 and 10 Hz with corresponding amplification factors of 5.2 and 6.2. These may indicate a gradual change in velocity across the basement boundary at ~10 m depth. The third resonance, which occurred at 15 Hz, may correlate with the refraction boundary at 5–6 m depth in the overburden layer. Both the frequencies and magnitudes of resonance derived from the H/H and H/V methods are reasonably well matched to the theoretical response curves computed by the reflection and transmission matrix and the two-dimensional finite difference methods.

Soil aggregation and root growth of perennial grasses in a constructed clay minesoil

Studying constructed soils (anthropogenic) in mined areas provides an opportunity to expand the existing knowledge about the formation and stabilization of aggregates, due to the magnitude of ecosystem disruption, that creates a “zero time” scenario. The aim of this study was to evaluate the relationship between the aggregation and the root growth of perennial grasses 103 months after the reconstruction of a constructed minesoil, in a coal mining area located in Candiota/Rio Grande do Sul State, Brazil. The evaluated plant species were Hemarthria altissima, Paspalum notatum cv. Pensacola, Cynodon dactylon cv. Tifton, and Urochloa brizantha. The grass roots promoted the recovery of the soil physical condition in the 0.00–0.10m layer, with a decrease in dry bulk density and an increase in soil macroporosity related to the formation of new aggregates. The decrease in root development of all species below 0.10m depth is the result of the restrictive soil physical conditions, with high bulk density and low macroporosity related to aggregates formed originally by compression. The results of root and soil attributes found in this study suggest a different soil-aggregation hierarchy in compacted constructed minesoils, where first a disintegration occurs of large cohesive aggregates formed by compression followed by a re-aggregation process, with sequential re-formation and stabilization of aggregates. The Urochloa brizantha showed a greater root density, volume, length and area, thus presenting a greater potential to recover the physical attributes of the degraded areas, especially those in the compacted layer below 0.10m depth. The recommendation of this and other species in the reclamation of constructed soils after coal mining should take into account the thickness of the topsoil layer because the roots of these species can grow into the overburden layers and thus accelerate the sulfurization process. The recovery of physical attributes of the constructed minesoil, especially below the 0.00–0.10m layer, is a slow process, possibly due to the low accumulation rates of organic carbon in this layer.

Seismic site conditions in Gangneung, Korea, based on Rayleigh-wave dispersion curves and topographic data

To determine the near-surface shear wave velocities (Vs) and characterize seismic site conditions in Gangneung, on the east coast of South Korea, passive and active surface waves were recorded at 136 sites. Dispersion images of the Rayleigh waves were obtained by the spatial autocorrelation method and inverted to Vs models. From these one-dimensional Vs models, the depth to the soft bedrock, average Vs at the top of the bedrock, average Vs of the overburden layer, average Vs in the top 30-m interval (Vs30), and average resonance frequency were estimated to be 16 ± 1 m, 481 ± 14 m/s, 254 ± 5 m/s, 374 ± 16 m/s, and 5.5 ± 0.3 Hz, respectively. A lower estimate for Vs30 and a relatively thick overburden layer make the downtown and agricultural areas in the region more prone to significant ground amplifications. Multiple regression analysis of Vs30 yielded a correlation coefficient of 0.79 with respect to the variables of elevation and topographic slope. Using this proxy-based empirical relationship, Vs30 values were computed at 13,583 sites covering the entire city. A microzonation map, constructed based on the Vs30 data, indicates that the ground in Gangneung is categorized mainly into B (44%), C (39%), and D (15%) National Earthquake Hazards Reduction Program site classes, with minor constituents assigned to the A and E classes.

Application of Process Simulation for Comparison of Contactless and Conventional Electrodeposition Methods for 3D Packaging

One of the key active manufacturing technologies for 3D integration is through silicon vias (TSVs), which involves etching of deep vias in a silicon substrate that are filled with an electrodeposited metal, and subsequent removal of excess metal by chemical mechanical planarization (CMP). Electrodeposition often results in undesired voids in the TSV metal fill as well as a thick overburden layer [[i],[ii]]. These via plating defects can severely degrade interconnect properties and lead to variation in via resistance, electrically open vias, and trapped plating chemicals that present a reliability hazard. Thick overburden layers result in lengthy and expensive CMP processing. We have recently developed a contactless technique that pursues a viable method of depositing a high quality metal inside vias with true bottom-up filling, using an additive-free deposition solution [[iii]]. The mechanism is based on a novel concept of electrochemical oxidation of backside silicon that releases electrons, and subsequent chemical etching of silicon dioxide for regeneration of the surface. The set-up consists of a reactor with two chambers. A silicon wafer with vias is placed and sealed between the two chambers. The front side of the wafer—the via side—is in contact with a deposition solution with an anode immersed in the bath. The backside of the wafer is in contact with an etchant solution (HF) with an immersed Pt mesh or graphite cathode. Silicon in contact with the etchant solution undergoes two-step dissolution, the first being electrochemical oxidation to SiO2 (see reaction R1) and the second involving chemical etching of SiO2(see reaction R2). Si + 2H2O = SiO2 + H2 + 2H+ + 2e- (R1) SiO2 + 6HF= H2SiF6 + 2H2O (R2) The electrons at the silicon/etchant solution interface resulting from first reaction are conducted through the bulk of silicon wafer to be consumed at the interface between the bottom of vias and the deposition solution. At this later interface, metal ions are reduced and deposited on the via bottom ensuring a bottom-up fill process. This prevents the formation of voids or seams because the driving force for the reaction is provided through the wafer rather than along a seed layer on the surface of the sample, as is typically the case in a traditional electro-deposition process. A comprehensive process model has been developed to analyze the kinetics and the mechanism of the deposition process and to uncover the role of different controlling steps. The model is used in the analysis of experimental data with the goal of selecting and optimizing the operational parameters to achieve high-quality fills with desired deposition rates. The process model includes the key aspects of the fluid mechanics, mass transfer, chemical reactions, and surface interactions/deposition occurring simultaneously in the process. [i]. S. Yoon, D. Yang, J. Koo, M. Padmanathan, and F. Carson, 3D TSV processes and its assembly/packaging technology, 3D System Integration, IEEE International Conference, pp.1-5 (2009) [ii]. T. Tsai and J. Huang, Electrochemical investigations for copper electrodeposition of through-silicon via, Microelectronic Engineering, 88, 2, pp. 195-199 (2011) [iii]. M. Zhao, R. Balachandran, Z. Patterson, R. Gouk, S. Verhaverbeke, F. Shadman, and M. Keswani, Contactless bottom-up electrodeposition of nickel for 3D integrated circuits, RSC Adv., pp. 45291-45299, 5 (2015) Figure 1