Wall Stability Research Articles

Failure Mechanisms and the Control of a Longwall Face with a Large Mining Height within a Shallow-Buried Coal Seam

The capabilities of mining equipment and technology in China have been improving rapidly in recent years. Correspondingly, in the western part of the country, the mining heights of longwall faces in shallow-buried coal seams have shown an increasing trend, resulting in enhanced mining efficiency. However, the problems associated with the possible failure of the coal wall then increase and remain a serious difficulty, restricting safe and efficient mining operations. In the present study, the 12401 longwall face of the Shangwan Coal Mine, Inner Mongolia, China, with a mining height of 8.8 m, is taken as an example to study the mechanisms underlying failure phenomena of coal walls and their control methods. Our results show that the failure region inward of the longwall face is small in shallow-buried coal seams, and the damage degree of the exposed coal wall is low. The medium and higher sections of the coal wall display a dynamic failure mode, while the broken coal blocks, given their initial speed, threaten the safety of coal miners. A mechanical model was developed, from which the conditions for tensile failure and structural instability are deduced. Horizontal displacement in the lower part of the coal wall is small, where no tensile stress emerges. On the other hand, in the intermediate and higher parts of the coal wall, horizontal displacement is relatively large. In addition, tensile stress increases first with increasing distance from the floor and then decreases to zero. Experiments using physical models representing different mining heights have been carried out and showed that the horizontal displacement increases from 6 to 12 mm and load-bearing capacity decreases from 20 to 7.9 kN when the coal wall increases in height from 3 to 9 m. Furthermore, failure depth and failure height show an increasing trend. It is therefore proposed that a large initial support force, large maximum support force, large support stiffness, and large support height of a coal wall-protecting guard are required for the improved stability of high coal walls, which operate well in the Shangwan coal mine.

Repair of the myometrial scar defect at repeat caesarean section: a modified surgical technique

BackgroundTo investigate whether the existing surgical technique for uterine closure at repeat lower segment Caesarean section (LSCS) can be modified to achieve adequate residual myometrial thickness (RMT) to ensure scar integrity and reduce complications in future pregnancy.MethodsWomen with a significant scar defect at repeat LSCS had the anterior uterine wall closed by a single experienced obstetrician with a technique focused on recognition, mobilisation and apposition of the retracted myometrial edges at the boundary of the defect. This was aimed at anatomical restoration of the lower segment. The RMT at the scar area was assessed by postnatal pelvic ultrasound scan at three months.ResultsThirty women with a history of at least one previous CS, incidentally found to have a large defect at operation underwent the technique with prior consent. A postnatal scan showed a mean residual myometrial thickness of 8.4 mm (SD ±1.3 mm; range 5.6–11.0 mm). The average operating time was 91 mins and the average blood loss 728 ml. Two women who underwent the repair have gone on to have a further uneventful CS.ConclusionThis modified technique resulted in scan evidence of an RMT indicative of uterine wall stability postnatally and offers the potential for reducing the risk of rupture and placenta accreta spectrum (PAS) in future pregnancy.

Bovine jugular vein conduit: What affects its elastomechanical properties and thermostability?

The aim of this study was to compare the mechanical properties and thermal stability of the venous wall depending on the treatment method used, and, accordingly, on those structural changes in the tissue that this treatment causes. Bovine jugular vein walls (BJVWs) cross-linked with glutaraldehyde (GA), ethylene glycol diglycidyl ether (DE), and Contegra commercial conduit were evaluated using uniaxial stretching [with and without pre-conditioning (PreC)], differential scanning calorimetry, amino acid analysis, and attenuated total reflection infrared spectroscopy. Fresh BJVW was used as a control. It was shown that failure stress in non-PreC GA-treated and DE-treated materials was lower than that in fresh and Contegra counterparts. Contegra samples were the stiffest among the tested materials. Cyclic preloading leads to distortion of the mechanical behavior of this material, which is heterogeneous in composition and structure. The denaturation temperatures (Td ) of all cross-linked BJVWs were higher than the Td of the fresh vein. The microstructures of the tested BJVWs did not exhibit any differences, but the cross-linking density and hydration of the DE-vein were the highest. GA-cross-linking or DE-cross-linking and isopropanol exposure (Contegra) changed the protein secondary structures of the tested materials in different ways. We hypothesized that the protein secondary structure and hydration degree are the main causes of differences in the mechanical properties and thermal stability of BJVW.

Enhanced surface area and thermal stability of mesoporous zirconia fibers modified by various oxides and the reinforcement mechanism

In the present work, four oxides (SiO2, TiO2, LaO1.5, or CeO2) were selected as additives to increase the surface areas and the pore wall stability of mesoporous zirconia (ZrO2) fibers in virtue of enhancing the skeleton stability and hindering the grain growth. The preparation, characterization, and thermal evolution of mesoporous ZrO2 fibers incorporated with different amounts of oxide additive and simultaneously combined with heat treatment via water vapour are presented. The effects of different oxide additives on the crystallization and phase transformation of mesoporous ZrO2 fibers were investigated by X-ray diffraction. N2 adsorption-desorption studies were conducted to investigate the changes in the porous structure of the ZrO2 fibers heat-treated at different temperatures. Scanning electron microscopy confirmed the mesoporous structure of the ZrO2 fibers. The oxide-added ZrO2 fibers heat-treated in the presence of water vapour exhibited a mesoporous structure with increased surface areas and thermal stability. The related reinforcing mechanisms were proposed. It was deduced that water vapour promoted the removal of the soft template, leading to the formation of a mesoporous structure with a high surface area. Meanwhile, the increase in the surface areas of mesoporous ZrO2 fibers with the incorporation of the oxide additive was mainly due to the enhanced thermal stability of the porous walls. The relationship between the mesoporous structure stability and the zirconia phase stability was fully discussed. This work provides a new route for enhancing the surface areas and structure thermal stability of mesoporous ZrO2 fibers.

Regression models and response surfaces to assess the external stability of soil nail walls

Debido a su rapida y economica ejecucion, la solucion geotecnica conocida como muros de soil nailing se utiliza ampliamente para la estabilizacion de taludes y excavaciones del terreno. En la etapa de diseno, la verificacion de la estabilidad externa del muro de soil nailing es uno de los criterios de aceptabilidad mas importantes. El principal objetivo de este trabajo es evaluar la estabilidad externa de muros de soil nailing, considerando la influencia de la variabilidad de su altura y los parametros geomecanicos del suelo in-situ. La metodologia probabilistica de diseno factorial 2k ha sido aplicada para generar 32 experimentos. Un muro de soil nailing vertical, con altura variable, bajo condiciones de carga pseudo-estatica, y ejecutado en suelo residual de roca granitica ha sido utilizado como modelo prototipo. Basandose en el analisis de las observaciones de los 32 experimentos, se han desarrollado tres modelos de regresion, los que pueden ser usados para predecir el valor de los factores de seguridad con realizaciones arbitrarias. Ademas, las observaciones muestran que los factores que mas influencia tienen sobre la estabilidad externa de muros de soil nailing son la altura del muro, la cohesion y el angulo de friccion del suelo in-situ.

Engineering formulas for dimensioning of deformation and damage zones in jointed rock mass under impact of blasting in quarries in Transbaikalia

Currently, there are five characteristic zones of blast-induced impact in quarries: crushed zone, radial cracking zone, severely fractured zone, blast-induced residual stress zone, and blast-induced load zone. Knowledge about the size of the zones is very important in the technological processes of mining. The size of the crushed zone governs the amount of ore over-grinding and loss. The size of the radial cracking zone is reflective of the spacing of blastholes. The size of the severe fracturing zone is characteristic of the geometry of an unstable pit wall area. The zone of blast-induced residual stresses in rock mass and its size affects the slope stability of pit wall. The purpose of this study is to develop engineering formulas for calculating the sizes of deformation and damage zones in jointed rock mass during short-delay blasting in quarries. The mathematical and numerical analyses of the complex theoretical expression provided engineering formulas for dimensioning of the blasting-induced impact zones in quarries. The reliability of the formulas is proved by the comparison with the full-scale testing data obtained in quarries in Transbaikalia.

Mechanical Behavior of the Reinforced Retaining Wall under Vehicle Load

This study primarily aims to explore the mechanical behavior and influence factors of the reinforced retaining wall subject to vehicle loads. Mohr–Coulomb model was adopted to simulate and analyze the structural characteristics of the reinforced retaining wall by the finite element method. Its mechanical behavior was investigated in accordance with relevant theories. The results showed that the vertical and horizontal maximum displacement of the reinforced retaining wall occurs at the wall surface of the retaining wall, the maximum internal soil pressure appears at the middle and lower part of the retaining wall, and the maximum tensile strain of the tension bar acts on the wall rupture surface. As impacted by static vehicle load, the largest settlement is located at the parking position, and the maximum horizontal displacement and wall stability will vary with the vehicle position. Moreover, the closer the vehicle to the reinforcement is, the greater the lateral Earth pressure will be imposed on the upper part of the reinforcement body. With the variation of the vehicle position, the tension stress of the geogrid will vary noticeably.

Interplay of the RNA Exosome Complex and RNA-Binding Protein Ssd1 in Maintaining Cell Wall Stability in Yeast.

ABSTRACTYeast cell wall stability is important for cell division and survival under stress conditions. The expression of cell-wall-related proteins is regulated by several pathways involving RNA-binding proteins and RNases. The multiprotein RNA exosome complex provides the 3′→5′ exoribonuclease activity that is critical for maintaining the stability and integrity of the yeast cell wall under stress conditions such as high temperatures. In this work, we show that the temperature sensitivity of RNA exosome mutants is most pronounced in the W303 genetic background due to the nonfunctional ssd1-d allele. This gene encodes the RNA-binding protein Ssd1, which is involved in the posttranscriptional regulation of cell-wall-related genes. Expression of the functional SSD1-V allele from its native genomic locus or from a centromeric plasmid suppresses the growth defects and aberrant morphology of RNA exosome mutant cells at high temperatures or upon treatment with cell wall stressors. Moreover, combined inactivation of the RNA exosome catalytic subunit Rrp6 and Ssd1 results in a synthetically sick phenotype of cell wall instability, as these proteins may function in parallel pathways (i.e., via different mRNA targets) to maintain cell wall stability.IMPORTANCE Stressful conditions such as high temperatures can compromise cellular integrity and cause bursting. In microorganisms surrounded by a cell wall, such as yeast, the cell wall is the primary shield that protects cells from environmental stress. Therefore, remodeling its structure requires inputs from multiple signaling pathways and regulators. In this work, we identify the interplay of the RNA exosome complex and the RNA-binding protein Ssd1 as an important factor in the yeast cell wall stress response. These proteins operate in independent pathways to support yeast cell wall stability. This work highlights the contribution of RNA-binding proteins in the regulation of yeast cell wall structure, providing new insights into yeast physiology.

Predictive assessment of the stability of quarry sides

The composition of the rocks composing the quarry sides and the approximate slope angles in accordance with the mining and geological conditions are described. The issues of creating observation stations are considered taking into account seasonal temperature fluctuations of the benchmarks. Observation materials are generalized, the degree of danger of deformations is established on the basis of observations of deformation speed. The mining safety control methods are described. The disadvantages of the approach to data processing and analysis are identified. A criterion for mine surveying prediction of the pit wall stability based on the comparison of critical and actual relative deformations is proposed. The purpose of the local forecast of wall deformation is to control the stability of non-working and working slopes of the sides, and to confirm the efficiency of the method used. The predictive assessment was carried out on the shift of working benchmarks on one of the open pits of Transbaikalia. It is suggested monitoring the stability of rocks using oscillograms obtained by seismic equipment.

The Diaphragm Wall Deflection Simulation Project was Tested in Ho Chi Minh City, Vietnam

Checking and calculating the stability of retaining walls and deep excavation are required in the design and construction of subterranean structures, particularly the DW500 reinforced concrete Wall-Plate. This is one of the most significant approaches to preventing landslides and settlement for buildings in the immediate vicinity. In fact, calculating and forecasting the DW500 retainer wall's stability and determining the influent area can provide a variety of options for reducing reinforced frame parts (retaining wall and shoring). This technology is now being explored and used for the most realistic structures in Vietnam, particularly in Ho Chi Minh City. This article uses the finite element technique (FEM –Plaxis 2D-2019) to calculate the lateral displacements, shoring, and outer foundation for the DW500 retaining wall.

Perkuatan Lereng pada Sempadan Sungai Jl. Sultan Agung Kabupaten Jember dengan Dinding Penahan Tanah Kantilever

The land collapsed on Jl. Sultan Agung, Jompo, Jember Regency was reported. A team from the Regional Disaster Management Agency (BPBD) found cracks in the ground under a shop since February 2019. This incident resulted in a landslide of a road with approximately 45 meters long and 10 meters wide that it blocked the river flow, and nine shophouses, which are the assets of the Jember Regency government, collapsed as deep as approximately 4 meters. The cantilever type retaining wall is designed in the landslide area as an effort to revitalize the banks of Jompo river on Jalan Sultan Agung. Cantilever wall design stability refers to SNI 8460: 2017 and was assisted by using the GEO 5 program. The stability of cantilever walls against overturning shows a safety factor value of 3.72 that greater than 2 (safe condition), whereas the stability of cantilever walls against sliding was 1.61 that greater than 1.5 (safe condition), and the stability of the bearing capacity was 8.18 that greater than 3 (safe condition). Cantilever wall structure using concrete quality (Fc ') 40 MPa, and reinforcement quality (Fy) 420 Mpa, with a diameter and a distance of 25 mm and 125 mm respectively. Additional reinforcement was given to the Cantilever Wall, i.e. a bore-pile with a diameter of 60 cm which was fixed to a depth of 6 meters.

Management of Malignant Chest Wall Tumors.

To analyse the malignant chest wall tumors in terms of histological types and confer option for resection, stabilisation and reconstruction, along with postoperative morbidity and mortality. Observational study. Department of Thoracic Surgery, CMH Rawalpindi, Lahore and Multan from January, 2010 to October, 2018. Patients who had histologically proven malignant tumors of chest wall and breast with bone involvement, and required resection, stabilisation, mesh reinforcement and muscle flap reconstruction, were included. Small soft tissue tumors without bony involvement which did not require reconstruction, primary tumors of spine, pancoast tumors and lung tumors involving chest wall were excluded from the study. Record of these patients including age, gender, histopathological type, reconstruction method used, postoperative complications, mortality and recurrence were noted. Data was analysed using descriptive statistics. The study included 86 patients with 61 (70.9%) males and 25 (29.1%) females; age ranging from 18 to 77 years with mean age of 47.84 ± 12.9 years. Palpable mass was the most common symptom occurring in 61 (70.9%) patients. Twenty-one (24.4%) had breast tumor with chest wall invasion. In the remaining cases, most common histological type was chondrosarcoma occurring in 13 (15.1%) patients, followed by Ewing sarcoma in 12 (14%) patients. The most common complication was post-thoracotomy neuralgia (PTN), occurring in 25 (29.1%) patients. Malignant tumors of the chest wall are rare entity which can be effectively treated with chest wall resection, mesh reinforcement for stabilisation and muscle flaps for reconstruction with acceptable postoperative complications, morbidity and mortality. Key Words: Primary, Malignant, Chest wall, Tumors, Chest wall reconstruction, Stability of chest wall.

Analysis of Stress and Deformation and Stability of Grouting Wall and Mud Control in Tunnel Excavation

To prevent the grout and fissure water from gushing out of the working face and to ensure the effective diffusion of grout along the fissure under the action of high grouting pressure, the grouting wall should be set up on the working face before grouting to ensure the grouting effect. This study found that under the grouting pressure of 4MPa, the grouting wall model with a thickness of 80cm is more stable than that with a thickness of 50cm. At the same time, for the grouting stop wall with a thickness of 80cm and a dip angle of 50°, both the horizontal deformation and the settlement of the vault have met the requirements of the construction specification in the process of simulated grouting calculation.

Theoretical preconditions for modeling wellbore stability and predicting hydraulic fracturing

One of the complex technological tasks in the process of drilling is to ensure the stability of the wellbore walls, as well as their modeling for further forecasting the state of the wellbore and the likelihood of hydraulic fracturing. This is due to the fact that most of the complications and factors affecting the equilibrium state of the wall are associated with external influences. The article discusses the mechanical and partially hydraulic aspects of solving the described problems associated with modeling the stability of the wellbore walls and predicting hydraulic fracturing. As a result of calculations, the necessary data are obtained for making a decision on the density of the drilling fluid for drilling the considered interval of rocks. The assumed model of the porous rock and the given calculation formulas make it possible to fully evaluate the influence of the formation fluid pressure on the mechanical processes in the rocks when they are opened by a well. Keywords: hydraulic fracturing; blade bit; steel ball-shaped toothed bit; polycrystalline diamond bit; laser drilling; impact rope drilling; rotary drilling.

Some issues of ensuring the stability of the walls of directional wells and preventing the absorption of process fluids

Most of the main types of complications in the process of drilling wells, such as collapses, taluses, collapses of the walls, the formation of caverns, etc., are associated with external mechanical and hydrodynamic effects on the walls of the wellbore. Therefore, ensuring the stability of the borehole walls is one of the urgent and difficult technological formation fluid pressure on mechanical processes in rocks when they are opened with a directional well, especially of horizontal wells. This article provides solutions to problems associated with hydraulic fracturing of a well and the condition of its prevention, calculation of generalized stresses in the rock formation for inclined well. As a result of this calculations, the necessary data are obtained for making a decision on the density of the drilling fluid to drilling the considered interval of rocks, as well as for making other technological decisions. The given calculation formulas make it possible to fully evaluate the effect of the formation fluid pressure on the mechanical processes in the rocks when they are opened by a horizontal well. Keywords: hydraulic fracturing; blade bit; steel ball-shaped toothed bit; polycrystalline diamond bit; laser drilling; impact rope drilling; rotary drilling.

Geomechanical substantiation of the northeastern pit wall stability in Kurzhunkul mine

Kurzhunkul magnetite deposit is located in the Kostanai Region of Kazakhstan and is an open pit mining project of Sokolovsko–Sarbay Mining and Production Association (SSGPO) since 1983. The current depth of the open pit is 240 m (Level -28 m). It is expected that Kurzhunkul pit reaches the depth of 290 m. The deformation determinant in Kurzhunkul mine is its geological structure represented by complex faulting. Special care and attention should be paid to the northeastern pit wall which is a zone of large and closely spaced tectonic faults essentially extended along the strike and dip of the deposit, and depthward the pit. Unfavorable bedding conditions in combination with weak physical and mechanical properties of fracture fillers can induce movement of rock blocks during extraction of mineral reserves from the weak zone of the northeastern pit wall. This study offers the geomechanical substantiation of stability of NE Kurzhunkul pit wall which is most heavily intersected by tectonic faults and has low strength characteristics. The study was carried out with grant financing in framework of Project No. AR08053358 Rock Mass Control Based on the Integrated Geomechanical Model toward Mining Safety.

Technical and technological support for preventing the destruction of well walls

At present stage of the development of the domestic gas production industry, the problem of increasing the volume of hydrocarbon production is extremely urgent for our state. In the dynamics, there is a significant increase in the volume of directional wells drilling. However, the drilling of such wells is associated with a number of problems. The main problems that may arise in this case are associated with insufficient stability of their bore, which in most cases leads to sticking of the drill string and a significant increase in material costs and production time for their elimination. Therefore, ensuring the integrity of the borehole walls during their drilling is a priority and extremely important problem in the system of measures aimed at improving the quality and improving the technical and economic indicators of their construction. The work is devoted to the improvement of the technology for preventing the destruction of the walls of directional wells, through the influence of technical, technological, mining, and geological factors on the change in the stress-strain state of the mass of the near-wellbore zone of the well. The production material on the sticking of the drill string was analyzed during the construction of wells in the Dnieper-Donets depression fields. It was found that the reasons for the loss of mobility of the drilling tool are mainly the violation of the integrity of the borehole walls as a result of caving and collapse of rocks, as well as the formation of keyseats on the borehole walls. Such complications arose, despite the observance of the operating and technological parameters, when deepening the well and recommendations for reducing keyseats on the walls of the well and preventing caving and collapse of rocks. The existing scientific and practical methods and approaches to prevent the loss of stability of the wellbore walls do not allow eliminating the indicated cause of complications, since the correct selection of the BHA, as well as the development of measures to reduce the intensity of capping and grooving, plays an important role. The paper proposes measures to prevent cavities and keyseats when drilling directional wells. The factors influencing the stability of the borehole walls in conditions prone to collapse and rock caving have been analyzed. The expediency of using baths for strengthening the walls of wells in clayey rocks has been established and substantiated. The formulation of a modified fuel-bitumen bath, the duration of which is 1.5÷5 times longer than that of a fuel-bitumen bath is proposed. A method is proposed for predicting intervals prone to complications associated with the loss of stability of the wellbore walls. According to industrial data, a technology has been proposed for installing a fuel-bitumen bath to prevent keyseats formation during well drilling. To eliminate the keyseats in the well, a bottom-hole assembly is proposed, which consists of stepped heavyweight drill pipes with simultaneous installation of tapered adapters at the transition points from a larger diameter of a drill string element to a smaller one and an eccentric carbide bit

Experimental Study on Axial Compression of an Insulating Layer through a Composite Shear Wall

Based on the research of composite walls at home and abroad, a construction method of continuous opening of the insulation layer in the specimen is proposed. In the edge component of the composite wall, the insulation layer should be thinned appropriately, the concrete on both sides should be thickened correspondingly, and U-shaped reinforcement should be used instead of stirrup. To study its axial compression test performance, five 1/2 scale composite shear wall specimens are tested under axial compression, including three composite wall specimens and two solid wall contrast specimens. The failure mode, load-bearing performance, deformation performance, and the collaborative work performance of wall are analyzed. The results show that the failure characteristics of the composite shear wall are similar to those of the solid wall, with splitting cracks at the corners and inverted triangular conical splitting at the top of the wall along the wall height direction, with no obvious bulging in the middle of the wall. The tie action of the ribs makes the concrete walls on both sides of the composite shear wall have good integrity and cooperative performance; the installation of the thermal insulation layer increases the overall thickness of the wall, improves the stability of the composite wall, and makes the composite wall axially compressed. The bearing capacity is not significantly reduced compared to the solid walls. Finally, according to the test results, the calculation formula of axial compression bearing capacity of composite shear wall is given, which provides the basis for the formulation of the code and engineering application.

Effect of Exogenous Auxin Treatment on Cell Wall Polymers of Strawberry Fruit.

The role of auxin in the fruit-ripening process during the early developmental stages of commercial strawberry fruits (Fragaria x ananassa) has been previously described, with auxin production occurring in achenes and moving to the receptacle. Additionally, fruit softening is a consequence of the depolymerization and solubilization of cell wall components produced by the action of a group of proteins and enzymes. The aim of this study was to compare the effect of exogenous auxin treatment on the physiological properties of the cell wall-associated polysaccharide contents of strawberry fruits. We combined thermogravimetric (TG) analysis with analyses of the mRNA abundance, enzymatic activity, and physiological characteristics related to the cell wall. The samples did not show a change in fruit firmness at 48 h post-treatment; by contrast, we showed changes in the cell wall stability based on TG and differential thermogravimetric (DTG) analysis curves. Less degradation of the cell wall polymers was observed after auxin treatment at 48 h post-treatment. The results of our study indicate that auxin treatment delays the cell wall disassembly process in strawberries.

Field and three-dimensional finite element investigations of the failure cause and rehabilitation of a composite soil-cement retaining wall

In this paper, the failure cause of a composite soil-cement (CSC) retaining wall is examined during reservoir excavation in the soft clay area of Bangkok, Thailand, by field investigation and three-dimensional finite element analyses. A rehabilitation method is also reported. The CSC wall consisted of precast reinforced concrete walls, soil-cement walls, and soil-cement columns encased with a stabilized mat. The original CSC wall configuration was designed based on the maximum soft clay thickness of 4 m found in the excavation areas from seven soil boreholes, providing an FSglobal of 1.61. However, a 50-m-long section of the composite wall failed unexpectedly. The field observation revealed that the wall collapsed from the loss of internal wall stability, namely, broken wall structures caused by bending failure. Continuous circular failure was observed due to the shear failure of the surrounding clays. This failure's primary cause was the unexpected soft clay thickness of 7 m induced by insufficient previous soil explorations. Finite element analyses confirmed that the unanticipated 7-m-thick soft clay facilitated significant failure since the FSglobal value was lower than 1.00. The soil and wall bodies exhibited a collapse because the shear and tensile failure points were fully developed in whole soil bodies and wall structures, respectively. Rehabilitation was performed by revising the original CSC wall configuration for supporting 7-m-thick soft clay, namely, increasing the embedded wall structure lengths and soil-cement rows to strengthen the CSC wall. The revised wall configuration improved the FSglobal during excavation to a value of 1.78, resulting in no visual failure after implementing the rehabilitation. During reservoir operation, the water storage level was kept at a level of −1.00 m to obtain a high FSglobal of 2.33.