Values Of Water Pressure Research Articles

Study on the Seepage Mechanism of Gaskets at the Joints of Shield Segments Based on Coupled Euler-Lagrangian Method

In the construction and operation stage of urban shield tunnels, joint leakage of shield is always an urgent problem to be solved. In order to further explore the waterproof performance of elastic rubber gaskets at segment joints, the finite element software ABAQUS (2022) was used to establish a fluid-solid coupling calculation model. The dynamic simulation of the leakage process at the segment joints under water pressure revealed the whole process of leakage at the segment joints and the instant water pressure value when the waterproof system failed. The results show that during the whole process from segment assembly to joint leakage, the elastic rubber gasket has experienced four key stages: gasket compression, confined water pushing, water wedge and final leakage. When the opening amount of the gasket is 6 mm and 10 mm, the contact stress between the gasket shows a “W” symmetrical distribution of high at both ends and low in the middle, and the peak of the contact stress at both ends of the interface is about twice as much as that in the middle. The waterproof threshold of the gasket is closely related to the opening amount of the gasket, and the waterproof threshold has the same trend with the initial contact stress between the gaskets.

Ultimate water level and deformation failures of the artificial dam in the coal mine underground reservoir

Coal mine underground reservoirs provide a new choice for the protection and utilization of water resources. This paper takes the underground reservoir of Wulanmulun Mine as the background, and takes the MB-1# artificial dam in the goaf of 31104–31116 working face of 3–1 coal seam as the research object. The theoretical model of artificial dam is established by elastic–plastic two-way slab theory, and the theoretical mechanical analysis and calculation are carried out. A similitude physical model for the coal mine underground reservoir was built by using the self-developed nested dual-dynamic-pressure similitude simulation testing system. Later, the mechanical response and deformation failure features of the artificial dam under different water pressure values were analyzed and the ultimate water pressure was determined. In addition, FLAC3D was used to determine the stress-seepage field-coupling model for the artificial dam. Using this model, the influence of water pressure on the multi-load coupling effect of the artificial dam and coal pillar dam was characterized. The dam form is optimized and the safety water level evaluation method of the dam body is proposed. The research results are as follows: (1) Based on the theory of elastic–plastic two-way slab, the theoretical analysis model of artificial dam is established, the expression of the ultimate water level function of artificial dam is derived, and the theoretical ultimate water head is determined to be 18.2 m (2) The seepage law of underground reservoir under different water pressures is obtained, and the ultimate water pressure of the model is determined to be 11.43 kPa. (3) It is clarified that the failure modes of the artificial dam are seepage failure and mechanical failure, and it is revealed that the groove area is the weakest position where the dam is most vulnerable to failure. In view of the failure modes of the dam, the I-shaped structure artificial dam is proposed. (4) A safe water level assessment method is proposed for the constructed artificial dam. According to the analysis of on-site monitoring data of MB-1# dam, the actual water level in the reservoir is within the allowable water level range of the artificial dam, and the whole reservoir is in a stable and relatively safe state at present. The reliability of this assessment method has been verified.

Experimental study on the failure mechanisms of non-cohesive soil landslide dams with different scales

The blocking of rivers by landslides is common in mountainous areas with deep and narrow valleys. Landslide dams may pose a severe threat to the safety of life and property downstream in the event of a sudden dam failure. The similarities and differences in failure characteristics between the large-scale and small-scale landslide dams are insufficiently understood. Relatively large-scale physical models to study the failure processes are expensive and time-consuming. Relatively small-scale experiments give a better opportunity to explore the failure mechanisms, but the scale effect needs to be considered. In this study, a large-scale test and three small-scale flume tests were conducted to study the failure characteristics of landslide dams with a scale ratio of 10:1. Experimental results showed that the large-scale and small-scale dam tests followed almost the same failure processes, which can be divided into three stages: seepage on the downstream surface, slope failure, and overtopping and erosion. But they differed in some quantitative outcomes such as the failure duration and pore water pressure value. The small-scale dam tests can be used to study the failure processes and mechanisms of landslide dams, but can not be used to predict the specific parameters due to the scale effect.

Numerical Study of Pore Water Pressure in Frozen Soils during Moisture Migration

Frost heaving in soils is a primary cause of engineering failures in cold regions. Although extensive experimental and numerical research has focused on the deformation caused by frost heaving, there is a notable lack of numerical investigations into the critical underlying factor: pore water pressure. This study aimed to experimentally determine changes in soil water content over time at various depths during unidirectional freezing and to model this process using a coupled hydrothermal approach. The agreement between experimental water content outcomes and numerical predictions validates the numerical method’s applicability. Furthermore, by applying the Gibbs free energy equation, we derived a novel equation for calculating the pore water pressure in saturated frozen soil. Utilizing this equation, we developed a numerical model to simulate pore water pressure and water movement in frozen soil, accounting for scenarios with and without ice lens formation and quantifying unfrozen water migration from unfrozen to frozen zones over time. Our findings reveal that pore water pressure decreases as freezing depth increases, reaching near zero at the freezing front. Notably, the presence of an ice lens significantly amplifies pore water pressure—approximately tenfold—compared to scenarios without an ice lens, aligning with existing experimental data. The model also indicates that the cold-end temperature sets the maximum pore water pressure value in freezing soil, with superior performance to Konrad’s model at lower temperatures in the absence of ice lenses. Additionally, as freezing progresses, the rate of water flow from the unfrozen region to the freezing fringe exhibits a fluctuating decline. This study successfully establishes a numerical model for pore water pressure and water flow in frozen soil, confirms its validity through experimental comparison, and introduces an improved formula for pore water pressure calculation, offering a more accurate reflection of the real-world phenomena than previous formulations.

Rainfall–Mining Coupling Effects on Slope Failure Mechanism and Evolution Process: A Case Study of Open-Pit to Underground Mining

This research examines how rainfall and mining affect the slope damage resulting from the transition from open-pit mining to underground mining. Using an unmanned aerial vehicle (UAV), the Huangniu slope of the Dexing Copper Mine was fully characterized, and experiments were conducted on rock samples from appropriate sites. First, the mechanical properties of the samples were measured. Then, the parameters of the similarity simulation experiments were derived based on the similarity theory. Subsequently, the rainfall, rock slope, data acquisition, and monitoring systems were designed. Finally, the rock mass failure with different slope angles was analyzed, and the deformation and damage patterns under the coupling effect were obtained. The results show that rainfall increases pore water pressure and moisture content. Rainfall and slope-slip water have more of an impact on the open-pit platform. The pore water pressure values on the upper rock mass rise faster than inside it. In the open-pit mining stage, the rock mass shifts slightly to the upper left. In the room mining stage, vertical fractures and goaf sinking occur. The fractures above the mine form a semi-ellipse. In the pillar mining stage, overlying rock displacement is evident and fractures persist. In the continuous pillar mining stage, the overlying rock collapses. The 65° slope model was the most damaged, while the 55° slope model was the least damaged. The results also suggest that the UAV guides sample selection.

Mechanisms of rainfall-induced landslides and interception dynamic response: a case study of the Ni changgou landslide in Shimian, China

Geological hazards, especially landslides and mudslides, are frequent in Caoke County, Sichuan Province, China. In September 2022, the mechanical parameters of the soil were obtained through a basic investigation of the landslide characteristics of Ni changgou. Upon that, the finite element-discrete element method was used to reconstruct the three-dimensional numerical model of the landslide on the right bank of Ni changgou, and the initiation mechanism of rainfall on landslide and the formation of debris flow impact dam process were simulated. Furthermore, the pore pressure, stability coefficient as well as displacement of the landslide body were analyzed. It turned out that with the increase of rainfall intensity, the pore water pressure value also increases, where pore water pressure rises rapidly. the slope is close to the unstable edge, Eventually, it tends to one under rainfall conditions, and due to gravity, the slide of the landslide is induced. The duration of landslide movement is about 200 s, the maximum average velocity of the landslide reaches 4.85 m/s, and the average movement distance is close to 500 m. In addition, this method is applied to the Chutougou debris flow, and the corresponding hazard analysis is added which could better show the treatment and application of debris flow in actual engineering.

MODELING OF PORE WATER PRESSURE IN FREEZING DISPERSED SOILS DURING MOISTURE MIGRATION

Frost heaving of soils is the main cause of engineering accidents in cold regions, but the current experimental as well as numerical studies focus on frost heaving deformation of soils, while there are fewer numerical studies on the main factors causing frost heaving deformation: pore water pressure. In this study, new calculation formulas of pore water pressure for saturated frozen soil are obtained by solving Gibbs free energy equation, and a thermo-hydraulic coupling model under different boundary conditions is constructed to calculate the pore water pressure values and water flow during water migration process. The results showed: (1) the pore water pressure of freezing soil with the ice lens is about ten times that without the ice lens, and the calculated results agree with the previous known experimental results; (2) The temperature of the cold end directly determines the upper limit of the pore water pressure value of freezing soil; (3) Pore water pressure decreases with depth much faster than the rate of temperature decrease.

Mechanical properties and acoustic emission evolution of water-bearing sandstone under triaxial conditions

Accidents occur frequently in underground chambers owing to the high-stress environment, poor stability of rocks, and unreasonable mining and construction layout. Significant damage to the deep surrounding rock mass by confined water can result in water inrush and flooding accidents. This study numerically investigated the mechanical properties and acoustic emission (AE) signal evolution mechanism of water-bearing sandstone in deep high-stress mining environments. The results showed that, the lower the confining pressure, the lower is the compressive strength of the specimen, resulting in evident failure. The confining pressure inhibited the radial strain and enhanced the strength of the specimen. Furthermore, under the same confining pressure and different water pressure, the higher the water pressure value, the more evident was the failure phenomenon, and the lower was the peak stress. The water pressure decreased the strength of the specimen and its ability to resist damage. Moreover, for the same water pressure, the smaller the confining pressure, the larger was the maximum AE number and the total cumulative amount of acoustic emissions. When the specimen reached the peak stress and produced macroscopic failure, the AE number reached the maximum value. Finally, the AE activity decreased as the water pressure increased, and the higher the water pressure, the smaller was the cumulative AE number. Owing to the existence of water pressure, the internal structure of the model specimen was affected by the softening effect, which decreased the model strength, thereby suppressing the AE activity of the specimen. Our findings can provide a basis for numerical simulation research on mechanical properties and AE evolution mechanism of water-bearing sandstone under three-way stress state.

Mechanical performance evaluation and structural optimization of ceramic lined thin-walled vacuum chambers

Thin-walled vacuum chamber internally supported by ceramic spacers is a promising approach to provide sufficiently robust, ultra-high vacuum compatible and low gap vacuum devices for high energy, high current, heavy ions accelerators. The mechanical performance of the ring shaped ceramic spacers is a key factor in the structural design of these vacuum chambers. An extensive campaign was devoted to develop methodologies and equipment for evaluating the mechanical and structural properties of the ceramic spacers and to optimize the chamber design. To this aim, a force analysis on single ceramic rings was first conducted, and formulas for calculating the elastic modulus and bending strength of the ceramic rings were derived. The elastic modulus and critical position strength limits of alumina and zirconia ceramic rings were tested using a mechanical testing platform. Based on the test results of a single ceramic ring, a preliminary design and processing of ceramic lined thin-walled vacuum chamber test samples was finalized. A testing device capable to apply known water pressure values was then designed and built to test the chamber ability to withstand externally applied forces and measure the mechanical parameters of the ceramic spacers. Thanks to this, the acceptable stress limits of alumina and zirconia ceramic rings as the supporting components of the vacuum chamber were obtained. Knowing these values, through an iteration process, the whole design and properties of the ceramic lined thin-wall vacuum chamber was optimized. Finally, to reduce the impact of eddy current heat effect on ceramic strength and outgassing, a suitable cooling structure was designed and implemented.

Analisis Fluktuasi Pemakaian Air Bersih di Pemukiman Desa

The need for water in an area is certainly different. Water needs in rural and urban areas are clearly different. This difference in water demand is influenced by water usage, and this difference in water usage will give rise to the value of water fluctuations. This study aims to determine the value of water usage fluctuations in rural residential areas so that water suppliers can know the exact amount of water discharge that will be distributed to customers in the area, in this way it is expected to make the water distribution system more effective, then it is also expected that the water supplier is able to know the number of water losses distributed to make improvements to the network system in the residential area. This research study is located in a residential area of the village, with a research time of 24 hours. From the results of observations in the field which were then calculated, the total debit of water usage per day from a total of 632 customers in the area was 320 m3 / day or 3.70 liters / second. As for the secondary data obtained, the total water distribution to customers in the village settlement area is 5169 m3 / month or 1.99 liters / second for the period April 2023. So that the water loss rate in the area is 46.21%. The peak hour debit is 5.39 liters/second with a water pressure value of 1.8 ATM.

Study of Water–Sand Inrush through a Vertical Karst Conduit Uncovered through Tunnel Excavation

The existence of karst compromises the safety of underground engineering, especially during tunnel excavations. Karst conduits are uncovered through tunnel excavations, which may lead to a water–sand inrush disaster. Taking a vertical karst conduit as an example, the process of water–sand inrush through a karst conduit could be viewed as being similar to the process whereby a water–sand mixture flows through the discharge opening of a storage bin. In this study, based on force analysis of a non-aqueous sand body above a karst conduit, the limiting diameter of the karst conduit under force equilibrium was obtained. Considering the effect of water on aqueous sand bodies, the criterion of water–sand inrush was established. We aimed to study water–sand migration and inrush through vertical karst conduits in order to obtain the distribution of the water pressure near a vertical karst conduit, and to explore the relationship between the conduit size, water pressure, and water–sand flow rate; therefore, a simulated testing system for analyzing water–sand inrush through a vertical karst conduit was developed. When the water pressure in the testing chamber was close to the critical head pressure of the water–sand inrush, the water–sand inrush exhibited a pattern of instability—migration—deposition—stability. When the water pressure in the testing chamber exceeded the critical head pressure, the water–sand flow increased first and then stabilized over time. With the increase in the set values of the water pressure and conduit size, the steady flow of the water–sand mixture increased gradually. When the karst conduit was opened suddenly, the actual water pressure in the testing chamber decreased significantly, due to the water–sand mixture flowing out of the testing chamber and the water supply lagging behind. With the stabilization of the water–sand flow, the actual water pressure gradually tended towards stability, but it was still lower than the initial set water pressure. When the karst conduit was opened, the values of the water pressure monitored by the pore pressure gauges all clearly decreased. With the stabilization of the water–sand flow, the water pressure gradually became stable. With the increase in the distance between the pore pressure sensor and the karst conduit, the water pressure values all increased gradually. These test results are significant for further studies of the formation mechanisms of water–sand inrush through vertical karst conduits.

The Effect of High Pore Water Pressure on Liquefaction Potential in Sidoarjo Mud Volcanoes (LUSI)

LUSI until now is still active and holds the potential for subsequent disasters due to the influence of high pore water pressure in the affected area. The presence of high pore water pressure will cause a decrease in effective stress and decrease in soil / rock strength. This type of subsequent disaster is closely related to the process of liquefaction which has the potential to occur with the addition of earthquake events. Analysis of liquefaction potential with empirical analysis on standard penetration test (SPT) based evaluation, with input of soil properties parameters, seismicity, and groundwater level parameters. The groundwater level parameter in the calculation will show a normal pore water pressure value in accordance with the depth of the water-saturated layer. Input of high pore water pressure parameters so far has not been done. CPT-u measurement data for pore pressure value input consists of 13 points of measurements was on the northern embankment, with the lowest level of stability. The input of these parameters will provide variations in the differences in the level of potential liquefaction in the study area. The result is changes occur in the decrease in the safety factor value ranging from 0.1-0.4 and the change in the liquefaction potential index (LPI) value from originally low to high, and originally high to very high. The anomaly input of pore pressure in CPT-u measurement results ranges from 40%-70% higher than normal pore pressure in the sand layer. Analysis of the potential for liquefaction in the study area showed that the results of the high-very high liquefaction potential in the northern and eastern research areas, and the low Liquefaction potential was in the southern and western areas.

Experimental study on hydraulic fracture behavior of concrete with wedge-splitting testing

Abstract The aim of this paper is to investigate the water pressure effects on hydraulic fracture behavior of concrete with wedge-splitting testing under dynamic loading. Five waterproof strain gauges are stuck along the crack path to observe the fracture process during the experiments. Four silicon water pressure sensors successfully measured the water pressure value on concrete face. The results show that the water pressure on crack faces accelerates the crack propagation of the concrete. The critical values of the splitting force decrease 26.7 and 25.6%, respectively, with the external applied water pressure of 0.2 and 0.4 MPa. Moreover, the hydraulic crack propagation speed increases at the beginning and tends to reach a peak value finally. The peak value of cracking speed is 11.08 m/s, which is high. Under dynamic loading, the water fails to fill the crack and only the trapped water interacts with the crack face. The water pressure is mainly a parabolic curve distribution along the crack path and the peak value decreases with the increase in the crack length.

ОБҐРУНТУВАННЯ ПАРАМЕТРІВ АНКЕРНОГО КРІПЛЕННЯ ПІДГОТОВЧИХ ВИРОБОК В УМОВАХ ІНТЕНСИВНИХ ВОДОПРИПЛИВІВ

Purpose. Improvement of the method of reducing water inflows into mine workings with using com-bined frame-roof bolting to ensure the stability of the mine workings, waterproofing and protection against the collapse of wet contour rocks inside the mine workings. Methods. When solving the problem of water filtration in deformed rock, the method of studying the state of a layered rock massif with a mine working in the presence of water-saturated layers in its vicinity, which was developed by the authors, as well as the finite element method, were used. Research results. As a result of the calculations, the stress values, the zones of inelastic defor-mations, the values of permeability coefficients, water pressure and water inflows have been obtained for the roadways supported with different number of roof bolts. It is shown that the number of roof bolts af-fects all these parameters around the roadway in the rock mass and in the water-saturated seam. If a larg-er number of roof bolts are installed, the processes of crack formation and, accordingly, rock fracturing are slower. After mining, if 3 or more roof bolts installed, intensity of water filtration process is minimal, but after 2-3 days water from the water-saturated seam begins to penetrate deep into the surrounding rocks. Roof bolting significantly reduces these processes, the using of a scheme with 5-9 roof bolts re-strains the movement of water and, most importantly, practically isolates the roadway from water-saturated rocks. Scientific novelty. For the first time, a numerical model has been created and the calculations have been completed for roadways supported with 1-9 roof bolts in conditions of intensive inflows over time from the moment of its building. Practical significance. Research and calculations make it possible to obtain a significant economic effect due to the setting of the optimal number of roof bolts and the reduction of the use of materials for supporting the roadway and, at the same time, to prevent water inflows and increase the stability of road-ways.

Numerical study of the influence of different water depths on the muzzle flow characteristics of machine gun

The mathematical and physical models of the underwater submerged gun are established to study the flow field distribution characteristics of the gun muzzle at different water depths. The Schnerr–Sauer cavitation model and the realizable k–ω transport turbulence model based on the Reynolds-averaged Navier–Stokes method are employed. The muzzle flow field for the 12.7 mm gun that is submerged launched underwater is numerically simulated by combining user-defined functions and overlapping mesh technology. The flow characteristics of the density, velocity, and pressure fields at the gun muzzle at different water depths are analyzed in detail. The results show that the muzzle flow morphology depends mainly on the pressure at different water depths. The muzzle flow field distribution in deep water is more flat due to the high value of water pressure, which limits the expansion of the muzzle gas, and the range of the velocity field of the muzzle flow field at 100 m is one time smaller than that at 1 m.

Elastic-plastic solution of circular hydraulic pressure tunnel based on D-P criterion

This work provides new findings on the theory of D–P failure criterion applied to the study of the analytic solution of the radius and stress of tunnel plastic zone and the periphery displacement of hydraulic pressure tunnel under uniform ground stress field. It focuses on elasto-plastic rock masses with the stage of construction and operation. The results that are obtained are compared to other calculation techniques and show that: The elastic-plastic solution calculated based on the theoretical model is larger than that based on the D-P Criterion, indicating safer conditions. The principal stress varies with the internal water pressure, and it firstly decreases to zero and then gradually increase in the plastic zone. With the internal water pressure keeping increasing to a high level, the principal stress in the elastic zone changes from tangential stress to radial stress in the radial distance-enlarging direction, which tends to reach the geostress. In this condition, the radial distance is related to the value of internal water pressure. The calculation results of this study are demonstrated to be in good agreement with those of numerical simulation under the same conditions.

Kalibrasi Model Epanet Dengan Uji Paired Sample Test pada Tinggi Tekan Model dan Tinggi Tekan Aktual

Local state drinking water company, Tirta Moedal, which its service area includes Mijen district, need to anticipate growing number of customers along with rapid growing population in the area for the last 5 years. One of the technical preparation is creation of Epanet model of pipe distribution network. Epanet model usage in water pipe network is addressed for time efficiency in hydraulics calculation if there are pipe network development. Calibration in water pipe model is comparing model simulation result to actual observation value of water pressure, by Paired Sample Test. Rising pipe life causing rising roughness and increasing headloss. The goal of this research is to calibrate the Epanet simulation model to actual condition by using modified roughness C value, conform to pipe age. Calibration results show average model simulation pressure is 20.92 m and average actual pressure is 18.94 m. Paired sample T test 2 tailed were conducted to both average pressure , resulting there is no real difference between simulation model to observation actual value, indicated by significant value is 0,124 > 0,05, the model is valid.

Analysis and Evaluation of West Semarang Distribution Pipe Network System Municipal Waterworks in Semarang City

The need for clean water is related to the growth rate and population density. High population density affects access to clean water. The population in the DWSS (Drinking Water Supply System) area of West Semarang is concentrated in three sub-districts, namely West Semarang (148,879 people), Ngaliyan (141,727 people), and Tugu (32,822 people). With the average population growth rate of Semarang City from 2011 to 2020 of 0.89%, the need for clean water will continue to increase. The condition of clean water services in Semarang City, which Municipal Waterworks manage, needs to be improved, both in terms of coverage and continuity of service distribution. The research method used is the method of field research and literature. Hydraulic data retrieval was obtained through field observations and water usage data from the internal Municipal Waterworks in Semarang City. The data were analyzed using the epanet program. From the analysis results, there were areas with significant differences in water pressure values , and at peak hours, there were areas that did not get sufficient water supply. It can be concluded that there are problems in the piping network in the West Semarang DWSS area.

Analisis Jaringan Distribusi Air Bersih Menggunakan Epanet 2.0 (Studi Kasus Perumahan Telkomas Kecamatan Tamalanrea)

Telkomas Housing is one of the complexes located in Tamalanrea District, Makassar City, South Sulawesi Province, and is an area that gets clean water distribution from Makassar City PDAM, but Telkomas Housing currently has a problem regarding water pressure. This research is intended to determine the need for clean water in Telkomas housing at present and in the future and make plans for the development of clean water distribution with the development of Telkomas housing. The results of the calculation of current water needs in Telkommas housing with the number of houses that are subscribed to are 405 houses, where the average daily water requirement is 340,200 liters/day, the average daily requirement is 391,230 liters/day and the peak hour is 7,924 liters/second. Then on the calculation of future water needs which is assumed to be 10 years in the future and the number of customers is 70% or about 770 houses, 2 educational facilities, and 3 religious facilities, where the average daily water requirement is 673,080 liters/day, the maximum daily requirement is 774,042 liters /day and peak hours of 15.678 liters/second. Then after analyzing the piping network on Epanet 2.0, there are several nodes whose pressure is still below the distribution pipe criteria or about 5.16 meters of water. each reservoir so that the water pressure value obtained has met the distribution pipe criteria and has been able to meet the water needs of PDAM customers in Telkomas housing both now and in the future.

An image recognition method for the deformation area of open-pit rock slopes under variable rainfall

Due to human mining action, relatively fragile open-pit mine rock slopes are prone to instability induced by heavy rain. Accurately identifying the information and area of deformation features on rock slopes is a key step for landslide disaster warning and prevention. This study simulates the deformation process of a large and steep rock slope in Dexing City, Jiangxi Province, China, under a variable rainfall event. The test results show that 1) the increased deformation region has positive relationships with increasing pore water pressure and water content values for the open-pit mine rock slope affected by heavy rainfall. 2) The infiltration of variable rainfall on the rock slope softens the weak interlayers and leads to failure of the slope toe first. Due to the action of gravity, the middle and upper parts slide and fail in sequence. In addition, an improved region growing segmentation method (IRGSM) is proposed based on the combination of multipixel seed points and point cloud coordinates for the image recognition of the deformation area of open-pit mine rock slopes. An error comparison with the original region growing segmentation method (ORGSM) shows that the average identification error in the X and Y directions by the method is reduced significantly (6.56% and 5.32% in IRGSM; 13.37% and 11.29% in ORGSM). This method may be applied to identify rock slope deformation in complex scenes with high precision.