Effect Of Water Pressure Research Articles

Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

This study aims at determining the effect of water pressure on the mechanical properties of concrete subjected to freeze-thaw (F-T) attack under the dynamic triaxial compression state. Two specimens were used: (1) a 100 mm × 100 mm × 400 mm prism for testing the loss of mass and relative dynamic modulus of elasticity (RDME) after F-T cycles and (2) cylinders with a diameter of 100 mm and a height of 200 mm for testing the dynamic mechanical properties of concrete. Strain rates ranged from 10−5·s−1 to 10−3·s−1, and F-T cycles ranged from 0 to 100. Three levels of water pressure (0, 5, and 10 MPa) were applied to concrete. Results showed that as the number of F-T cycles increased, the mass loss rate of the concrete specimen initially decreased and then increased, but the RDME decreased. Under 5 MPa of water pressure and at the same strain rate, the ultimate compressive strength decreased, whereas the peak strain increased with the increase in the number of F-T cycles. This result is contrary to the variation law of ultimate compressive strength and peak strain with the increase in strain rate under the same number of F-T times. With the increase in F-T cycles or water pressure, the strain sensitivity of the dynamic increase factor of ultimate compressive strength and peak strain decreased, respectively. After 100 F-T cycles, the dynamic compressive strength under all water pressure levels tended to increase as the strain rate increased, whereas the peak strain decreased gradually.

Low-Salinity Polymeric Nanofluid-Enhanced Oil Recovery Using Green Polymer-Coated ZnO/SiO2 Nanocomposites in the Upper Qamchuqa Formation in Kurdistan Region, Iraq

Many carbonate oil fields are known to be oil-wet, which makes production more difficult. Enhanced oil recovery methods have been developed in the past to reduce interfacial tension (IFT) and improve displacement efficiency by injecting higher viscosity solutions. This work focused on the production of ZnO/SiO2 nanocomposite (NC) that is designed to reduce IFT during water-flooding of an oil-wet rock sample from the Upper Qamchoqa carbonate formation. A natural polymer was used as a mobility modifying agent to increase oil recovery. In addition, the effects of water salinity, NC concentration, temperature, and pressure have been analyzed to determine potential improvement on the performance of the stated chemical additives to the injected fluids. ZnO/SiO2/xanthan NC was prepared in a simple, economical, and importantly, green way using the pomegranate seed extract and characterized with scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The potential effect of the polym...

Effect of water pressure on fracture parameters of concrete

The effects of water pressure in the crack on the fracture parameters of a concrete beam under three-point bending were discussed. A novel sealing device for hydraulic loading was proposed to simulate the hydraulic load in a test beam. Experimental results showed that the proposed novel sealing device had less effect on the crack propagation in concrete. Then, 12 three-point bending tests of concrete beams with different water pressure in the crack were conducted. A method for determining the fracture parameters of concrete within water pressure was introduced. Moreover, an analytical method based on the relationship of the water pressure and crack width was employed to determine the water pressure distribution along the crack surface. The experimental results indicated that the water pressure applied in the crack had little effect on the initiation fracture toughness but decreased the unstable fracture toughness of concrete. Moreover, as water pressure increased from 0.0 MPa to 0.3 MPa, the unstable fracture toughness decreased by 17.5%, and the cohesive fracture toughness decreased by 21.8%.

Corrigendum to “Effects of Initial Porosity and Water Pressure on Seepage-Erosion Properties of Water Inrush in Completely Weathered Granite”

Corrigendum to “Effects of Initial Porosity and Water Pressure on Seepage-Erosion Properties of Water Inrush in Completely Weathered Granite”

An optimal method to design reinforced concrete lining of pressure tunnels

The utilization of the lining type in pressure tunnels is highly dependent on the geological and hydraulic conditions. There are two types of lining, namely concrete and steel lining but steel lining is one of the most expensive arrangements. To decrease the length of steel lining in these tunnels, the concrete lining, which prevents water seepage from the surrounding rock mass, is the appropriate alternative. In this work, a special attention is devoted to limit water losses in the concrete lining of pressure tunnel based on the critical reinforcing ratio in concrete lining. In order to evaluate the effect of internal water pressure on the permeability coefficient variation of the concrete lining and the surrounding rock mass, some simulations of reinforced concrete lining is implemented in the ABAQUS finite element software based on the coupled pore fluid-stress analysis. The results obtained indicate that although the critical reinforcing ratio has an important role in capturing the seepage flows and water losses, it is not sufficient to rely only on this parameter. However, among the various influential factors involved, a suitable arrangement of the reinforcement in the concrete lining should also be considered.

Variations in Hydraulic Properties of Sendimentary Rocks Induced by Fluid Injection: The Effect of Water Pressure

Variations in Hydraulic Properties of Sendimentary Rocks Induced by Fluid Injection: The Effect of Water Pressure

Effects of Initial Porosity and Water Pressure on Seepage-Erosion Properties of Water Inrush in Completely Weathered Granite

In order to investigate the water inrush mechanism in completely weathered granite, a large-scale triaxial testing system is designed and manufactured, which can induce the mass transfer and monitor the flow properties. Using this system, the effects of water pressure and initial porosity on the mass transfer and flow properties were determined, and the relative critical conditions for water inrush were proposed. The results indicate that (1) the particle transfer could cause an increase in porosity, permeability, and water inflow, which is the essential reason for water inrush in completely weathered granite. (2) Due to the effect of particle transfer, the flow properties may change from a Darcy to a non-Darcy flow, which is a key signal for water inrush. (3) With the increase of water pressure, the mass transfer, permeability, and water inflow increased gradually, and a critical value (p=0.6 MPa) that caused the water inrush was obtained. Furthermore, with the decrease of initial porosity, the mass transfer and flow properties were suppressed rapidly, and a critical porosity (0.23) to anti-inrush was observed. The results obtained can provide an important reference for understanding the mechanism, forecasting the risk, and taking the effective control measures for water inrush.

Experimental investigation of abrasive waterjet machining of Nickel based superalloys (Inconel 625)

This work explores abrasive waterjet machining (AWJM) process to improve the machining capabilities of conventional water jet machine by adding abrasive particles to the water jet. The addition of abrasive particles can turn the water jet into a modern machining tool for all materials. The experimental data of cutting parameters for hard-to-machine metal Inconel 625 is obtained. Inconel 625 is machined using an abrasive water jet and the effect of water pressure, abrasive flow rate, stand-off distance, surface quality has been studied and the response parameters are investigated. Experiments were conducted, based on Taguchi’s L18 orthogonal array and the process parameters were optimized using Grey relational analysis. Further, the morphological study is made using scanning electron microscope (SEM) on the samples that were machined at optimized parameters. It is observed from the experiment that Stand-off distance is the most influencing parameter among the input parameters.

Microseismic monitoring and stability analysis of the right bank slope at Dagangshan hydropower station after the initial impoundment

The right bank slope of the Dagangshan hydropower station in China has suffered from reservoir water pressure and seepage effects since the initial impoundment process. This paper describes the microseismic monitoring system and impoundment process of the Dagangshan hydropower station. Microseismic activity was detected in the right bank slope after the initial impoundment by the microseismic monitoring system. The spatiotemporal characteristics of the microseismic events and the piezometer monitoring results are used to confirm the conductive seepage pathways, the porous rock mass and the water recharge source in the right bank slope. Based on the geological conditions of the porous rock mass identified by microseismic and piezometer monitoring, a simplified two-dimensional (2D) finite element model is developed. A 2D finite element analysis is then applied to explore the damage mechanisms of local regions of the right bank slope after the initial impoundment. In addition, the load/unload response ratio theory is used to predict the failure of the slope based on the seismic source information obtained by the microseismic monitoring system. According to the actual geological conditions of the right bank slope, a simplified 3D numerical model is developed for the stability analysis of the right bank slope after the initial impoundment. Based on the porous rock mass identified by the microseismic monitoring, the effective stress is considered in the stability analysis. The safety factor of the right bank slope including the effective stress is 1.645, which indicates that the slope was stable after the initial impoundment. The microseismic monitoring technique can record disturbances caused by seepage effects in deep rock masses after the initial impoundment process in real time.

Effect of water pressure and soaking time on the selective oxidation of DP980 advanced high strength steel

Due to the limited heating power in non-oxidation furnace of continuous strip processing facilities of heating stage, selective oxidation with higher oxygen pressure is practically inevitable, which will greatly influence the quality of coating during immersion into the zinc bath. In this paper, the oxidation behaviors of DP980 advanced high strength steel are studied during annealing in a pure H2 atmosphere with controlled water pressure ranging from 0.033 to 0.094 bar (PH2O/PH2) and soaking time from 30 s to 2 h. The oxidation proceeds as a combination of external formation of Mn oxides and internal formation of Mn2SiO4, MnSiO3 and SiO2 from the subsurface of the steel into the matrix. As the water pressure increases from 0.033 to 0.094 bar, it can be seen that the amount of oxide particles and coverage on the surface of the steel seems to decrease initially and increase afterwards. The sequence of oxides determined by oxygen partial pressure was calculated and illustrated using thermodynamics with alloys activity. Oxide growth mechanism during annealing and the effect of water pressure on the amount of oxide particles were also discussed.

Numerical study for dynamic response of marine sediments subjected to underwater explosion

This paper developed a three-dimensional numerical model for saturated soil response induced by underwater explosion in marine environment. Unlike previous studies, three new features are included in the present model: (1) genuine detonation with real explosive materials; (2) coupled ALE (Arbitrary-Lagrangian-Eulerian)-Lagrangian algorithm for large seabed deformation; and (3) u-p formulation considering pore water pressure effect. The proposed explosion model is validated against experiment data available in the literature. Several parametric studies are carried out to investigate seabed response considering various soil types and TNT equivalent. Time series of total stress and pore pressure from sandy bed and clayey bed subjected to explosive loads are presented. Special attention is given to the distribution of peak total stress and pore pressure during propagation of blast wave. To facilitate engineering practice, a series of formulas for evaluating attenuation of peak total stress and pore water pressure are proposed.

Wollastonite carbonation in water-bearing supercritical CO2: Effects of water saturation conditions, temperature, and pressure

Abstract The carbonation of silicates in water-bearing supercritical CO2 (scCO2) can affect the performance of CO2-enhanced subsurface operation. This study investigated the effects of water, temperature, and pressure on the carbonation of wollastonite (CaSiO3) in water-bearing scCO2 at 35–93 °C, 25–125 bar, and from dry conditions to 140 times more water than needed for saturation (140 × Sw). The extent of reaction increased with more water, higher pressure, and interestingly, lower temperature. In addition, for the first time, we report on water-bearing scCO2–silicate reactions for samples with varying prior histories of water saturation conditions, temperature, and pressure. For a sample initially reacted at 100% water saturation (1 × Sw) and then with 45 × Sw, the final reaction extent was smaller than the sample reacted only with 45 × Sw. Similarly, for a sample initially reacted at 60 °C and then at 35 °C, the reaction extent was smaller than for a sample reacted only at 35 °C. In contrast, for a sample initially reacted at 50 bar and then at 100 bar, the reaction extent was the same as for a sample reacted only at 100 bar. The amorphous silica layers formed on the particle surfaces are more permeable with more water and lower temperature, and are not affected by pressure. These findings provide new insights into the extent to which water-bearing scCO2–silicates reactions depend on environmental conditions and the reactions' impacts on subsurface CO2 injection.

Experimental analysis of the water salinity impact on the energy consumption of small desalination plants

In the present research, the topic of desalination is investigated both theoretically and experimentally. In the theoretical part, information is provided on water consumption aspects in Greece and worldwide, on the problem of water shortage globally and on the solution of desalination. In the experimental part, the pilot Reverse Osmosis (RO) unit used for the conduction of this study is presented in detail, while following that, the experimental results are analysed, mainly focusing on the energy consumption of the RO desalination unit. Additional results concerning the effect of water pressure and water salinity on the energy consumption and the clean water production flow rate of the experimental desalination unit are presented and the relative conclusions are drawn.

Study on thermal deformation behavior and microstructural characteristics of wire electrical discharge machining thin-walled components

Wire electrical discharge machine (WEDM) has been successfully applied to aerospace field, mold industry and medical apparatus and instruments due to its excellent abilities. However, thermal deformation behavior of thin-walled components is always ignored due to no macro-force in the WEDM process, and different materials processed by WEDM have different thermal deformation behaviors. This work mainly describes the complex thermal deformation behavior during the WEDM processing the thin-walled components of three typical engineering materials, namely AISI H13, SKD11, and Inconel 718. Firstly, a large number of experiments are conducted to investigate the effects of pulse-on time, water pressure, and wire speed on the thermal deformation of three different materials. Through analyzing the experimental results, it was not only confirmed the significance and universality of thermal deformation in WEDM processing different materials, but also revealed that the effects of physical properties of workpiece materials and process parameters of WEDM on the deformation scale. Furthermore, it was concluded that the yield strength and thermal conductivity of materials both paly the significant roles in the thermal deformation. What's more, we also presented micro-structure characteristics and residual stress of thin-walled components with the thermal deformation. Eventually, several more complex but interesting deformation phenomena during the WEDM process were introduced and discussed.

Numerical study of catalytic steam reforming of aviation kerosene at supercritical pressures

A new two-dimensional numerical model is proposed for supercritical catalytic steam reforming of Chinese aviation kerosene No. 3 (RP-3) in order to suppress the coke formation during regenerative cooling of scramjet engines. A well-established wall catalytic steam reforming mechanism is used together with the newly proposed coke formation models to account for the coke formation during wall catalytic steam reforming reaction of RP-3. This wall catalytic steam reforming and coking model is coupled with computational fluid dynamics (CFD) codes to provide information of the flow field variables in the mini-channel reactor. The model is validated against experimental results. The effects of water content, pressure and inlet flow velocity on the wall catalytic reforming of RP-3, particularly on the coke formation, are then studied and analyzed. The simulation results show that higher water content and higher pressure can effectively suppress coke formation and increase the conversion of RP-3. The increase of inlet flow velocity, however, can reduce coke deposits but results in low conversion of RP-3.

Numerical modelling of pile installation and set-up effects on pile shaft capacity

Soil set-up effects significantly contribute to the increase in shaft bearing capacity of prefabricated displacement piles installed in saturated clay. This paper quantitatively distinguishes the effects of two contributing factors, (1) excess pore water pressure dissipation and (2) aging. A large-deformation coupled analysis using a finite-element scheme is used to carry out the analyses. The model only captures excess pore water pressure effect and the differences in skin friction between field measurements and numerical predictions are considered as aging. The results show that the coefficient of lateral earth pressure adjacent to the pile skin increases over time to 2.5 times of the initial coefficient (at rest). Numerical simulation of load–displacement response of static load tests at different times show that the contribution of the first factor which increases the shaft resistance is initially more significant. As time passes, the magnitude of the second factor (aging) becomes more significant..

The changes of hydrocarbon generation and potential in source rocks under semi-closed conditions with 50–840 bar water pressure

ABSTRACTIn order to investigate the effects of water pressure on hydrocarbon yields and potential in source rocks, carbonaceous mudstone from drilling in Liaohe Basin was pyrolyzed in simulation with constant water pressure and high-water-pressure experiments. Results demonstrate that the times of expelling hydrocarbon remarkably promote source rocks yielding liquid hydrocarbons. Increasing water pressure may increase the reaction of generating bitumen and oil, and enhance liquid hydrocarbons generation. Results of TOC, Rock-Eval, and elemental analysis in this study suggest that carbonaceous mudstone dominated by type-III kerogen remains a large number of hydrocarbon-generating potential, which may indicate that carbonaceous mudstone has a good potential to yield deep oil and natural gas. Besides, vitrinite reflectance may be the most suitable parameter to describe the maturity of source rocks.

Failure Behavior of Granite Affected by Confinement and Water Pressure and Its Influence on the Seepage Behavior by Laboratory Experiments.

Failure behavior of granite material is paramount for host rock stability of geological repositories for high-level waste (HLW) disposal. Failure behavior also affects the seepage behavior related to transportation of radionuclide. Few of the published studies gave a consistent analysis on how confinement and water pressure affect the failure behavior, which in turn influences the seepage behavior of the rock during the damage process. Based on a series of laboratory experiments on NRG01 granite samples cored from Alxa area, a candidate area for China’s HLW disposal, this paper presents some detailed observations and analyses for a better understanding on the failure mechanism and seepage behavior of the samples under different confinements and water pressure. The main findings of this study are as follows: (1) Strength reduction properties were found for the granite under water pressure. Besides, the complete axial stress–strain curves show more obvious yielding process in the pre-peak region and a more gradual stress drop in the post-peak region; (2) Shear fracturing pattern is more likely to form in the granite samples with the effect of water pressure, even under much lower confinements, than the predictions from the conventional triaxial compressive results; (3) Four stages of inflow rate curves are divided and the seepage behaviors are found to depend on the failure behavior affected by the confinement and water pressure.

CO2 separation performance by chitosan/tetraethylenepentamine/poly(ether sulfone) composite membrane

ABSTRACTCO2 separation from CO2/N2 (20:80) gas mixture has been demonstrated by tetraethylenepentamine blended with chitosan (CS‐TEPA) membrane. Optimization of CS and TEPA weight ratio were carried out based on characterization details involving thermogravimetric analysis, Fourier transform infrared spectroscopy, X‐ray diffraction, atomic force microscope, and field emission scanning electron microscope. Effects of water flow rate, pressure, and temperature were concurrently studied on CS‐TEPA membranes through gas permeation. Almost twofold increase in CO2 permeance (24.7 GPU) was detected in CS blend with 30% (w/w) of TEPA (CS70) as compared to pure CS membrane (12.5 GPU). CS70 yielded CO2/N2 selectivity of 80 whereas CS demonstrated a maximum of 54 at 90 °C. The membrane also exhibited improved stability at temperatures less than 120 °C which was evident from TGA isotherm trace. The proposed composite membrane can be a promising candidate for flue gas separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45206.

Experimental study on water fracture interactions in concrete

A novel sealing device that has a minimal effect on the mechanical behaviour of concrete specimens is proposed in this paper. This device connects one side of silicon plates to a specimen using two specially designed clamps, instead of adhesive and screws the other side of the plates together to a steel plate. Several experimental wedge-splitting tests under compact tension are conducted with and without this sealing device to investigate the effect of water pressure on concrete crack propagation. The fracture experiments for concrete under different water pressures and different loading rates are carried out by wedge-splitting tests with the water pressure applied using this novel device. The water distribution is obtained based on experimental data recorded by five pressure transducers present at the tip of a notched crack, and the results show that the internal water pressure consists of a constant curve and a parabolic curve. The water within the crack has sufficient time to enter the crack when the specimen is subjected to a slow split loading, and the water front during slow loading test exceeds that of the fast loadings when reaching the same CMOD. The effect of the water interactions in concrete is severe in quasi-static conditions rather than in fast loading conditions during crack sudden opening. The loading rate plays a dominant role in the water pressure distribution and crack propagation.