Application of high-pressure water jet technology and the theory of rock burst control in roadway

This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone is formed by using high-pressure water jet to cut the coal wall in a continuous and rotational way. In order to study the influence law of weak structure zone in surrounding rock, this paper numerically analyzed the influence law of weak structure zone, and the disturbance law of coal wall and floor under dynamic and static combined load. The results show that when the distance between high-pressure water jet drillings is 3 m and the diameter of drilling is 300 mm, continuous stress superposition zone can be formed. The weak structure zone can transfer and reduce the concentrated static load in surrounding rock, and then form distressed zone. The longer the high-pressure water jet drilling is, the larger the distressed zone is. The stress change and displacement change of non-distressed zone in coal wall and floor are significantly greater than that of distressed zone under dynamic and static combined load. And it shows that the distressed zone can effectively control rock burst in roadway under dynamic and static combined load. High-pressure water jet technology was applied in the haulage gate of 250203 working face in Yanbei Coal Mine, and had gained good effect. The study conclusions provide theoretical foundation and a new guidance for controlling rock burst in roadway.

In situ experimental study on TBM excavation with high-pressure water-jet-assisted rock breaking

China’s first high-pressure hydraulically coupled rock-breaking tunnel boring machine(TBM) was designed to overcome the rock breaking problems of TBM in super-hard rock geology, where high-pressure water jet system is configured, including high-flow pump sets, high-pressure rotary joint and high-pressure water jet injection device. In order to investigate the rock breaking performance of high-pressure water-jet-assisted TBM, in situ excavation tests were carried out at the Wan’anxi Water Diversion Project in Longyan, Fujian Province, China, under different water jet pressure and rotational speed. The rock-breaking performance of TBM was analyzed including penetration, cutterhead load, advance rate and field penetration index. The test results show that the adoption of high-pressure water-jet-assisted rock breaking technology can improve the boreability of rock mass, where the TBM penetration increases by 64% under the water jet pressure of 270 MPa. In addition, with the increase of the water jet pressure, the TBM penetration increases and the field penetration index decreases. The auxiliary rock-breaking effect of high-pressure water jet decreases with the increase of cutterhead rotational speed. In the case of the in situ tunneling test parameters of this study, the advance rate is the maximum when the pressure of the high-pressure water jet is 270 MPa and the cutterhead rotational speed is 6 r/min. The technical superiority of high-pressure water-jet-assisted rock breaking technology is highlighted and it provides guidance for the excavation parameter selection of high-pressure hydraulically coupled rock-breaking TBM.

EVOLUTION OF LIQUID WATER CONTENT IN A SEA FOG CONTROLLED BY A HIGH-PRESSURE PATTERN

On March 16–17, 2008, a sea fog occurred in Dianbai in the west of Guangdong Province and was accompanied by a high-pressure synoptic system. Using comprehensive observation datasets, this study analyzes the evolution of liquid water content during this sea fog and investigates the relationships between liquid water content and the average diameters and count densities of fog droplets, air temperature, wind speed and turbulence exchanges. The main results are presented as follows. (1) The sea fog showed a quasi-periodic oscillation characteristic, i.e., it developed, disappeared and then developed again. (2) During the sea fog, the number of fog droplets changed significantly while the changes in average diameter of the fog droplets were relatively small. The development and disappearance of the sea fog correlated significantly with the fog droplet numbers. (3) The air-cooling mechanism played a significant role in sea fog formation and development. However, the influences of this mechanism were not evident during fog persistence. (4) During sea fog formation, weak turbulence exchanges were helpful for fog formation. During sea fog development and persistence, liquid water content increased when turbulence exchanges weakened, and vice versa. The changes in turbulence exchanges were closely related to the quasi-periodic oscillations observed in sea fog presence.

Numerical Simulation Analysis of the Transformer Fire Extinguishing Process with a High-Pressure Water Mist System under Different Conditions

To thoroughly study the extinguishing effect of a high-pressure water mist fire extinguishing system when a transformer fire occurs,a 3D experimental model of a transformer is established in this work by employing Fire Dynamics Simulator(FDS)software.More specifically,by setting different parameters,the process of the highpressure water mist fire extinguishing system with the presence of both diverse ambient temperatures and water mist sprinkler laying conditions is simulated.In addition,the fire extinguishing effect of the employed high-pressure water mist system with the implementation of different strategies is systematically analyzed.The extracted results show that a fire source farther away fromthe centerline leads to a lower local temperature distribution.In addition,as the ambient temperature increases,the temperature above the fire source decreases,while the temperature and the concentrationof theupperflue gas layer bothdecrease.Interestingly,after thehigh-pressurewatermist sprinkler begins to operate,both the temperature distribution above the fire source and the concentration of the flue gas decrease,which indicates that the high-pressure water mist system plays the role of cooling and dust removal.By comparing various sprinkler laying methods,it is found that the lower sprinkler height has a better effect on the temperature above the fire source,the temperature of the upper flue gas layer,and the concentration of the flue gas.Moreover,when the sprinkler is spread over thewhole transformer,the cooling effect on both the temperature above the fire source and the temperature of the upper flue gas layer is good,whereas the change in the concentration of the flue gas above the fire source is not obvious compared to the case where the sprinkler is not fully spread.

Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams

Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.

A Numerical Study on the Extinguishing Performances of High-Pressure Water Mist on Power-Transformer Fires for Different Flow Rates and Particle Velocities

In order to study the extinguishing performance of high-pressure-water-mist-based systems on the fires originating from power transformers the PyroSim software is used.Different particle velocities and flow rates are considered.The evolution laws of temperature around transformer,flue gas concentration and upper layer temperature of flue gas are analyzed under different boundary conditions.It is shown that the higher the particle velocity is,the lower the smoke concentration is,the better the cooling effect on the upper layer temperature of flue gas layer is,the larger the flow rate is and the better the cooling effect is.

A study of hydrate plug formation in a subsea natural gas pipeline using a novel high-pressure flow loop

The natural gas pipeline from Platform QKI8-1 in the southwest of Bohai Bay to the onshore processing facility is a subsea wet gas pipeline exposed to high pressure and low temperature for a long distance. Blockages in the pipeline occur occasionally. To maintain the natural gas flow in the pipeline, we proposed a method for analyzing blockages and ascribed them to the hydrate formation and agglomeration. A new high-pressure flow loop was developed to investigate hydrate plug formation and hydrate particle size, using a mixture of diesel oil, water, and natural gas as experimental fluids. The influences of pressure and initial flow rate were also studied. Experimental results indicated that when the flow rate was below 850 kg/h, gas hydrates would form and then plug the pipeline, even at a low water content （10%） of a water/oil emulsion. Furthermore, some practical suggestions were made for daily management of the subsea pipeline.

Water Deficit Stress Effects on Corn (<i>Zea mays</i>, L.) Root:Shoot Ratio

A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation management. Water deficit stress (Dstress) was quantified by the number of days when the water content in the surface 0.3 m deviated from the water content range determined by the Least Limiting Water Range (LLWR). Root and shoot samples were collected at the V6, V12, and R1 growth stages. There was no significant correlation between Dstress and shoot or root biomass at the V6 growth stage. At the V12 and R1 growth stages, there were negative, linear correlations among Dstress and both root biomass and shoot biomass. The proportional decrease of shoot biomass was greater than the proportional decrease in root biomass, leading to an increase in the root:shoot ratio as water deficit stress increased at all growth stages. Determining restrictive soil conditions using the LLWR may be useful for evaluating improvement or degradation of the soil physical environment caused by soil management.

High-pressure capacity expansion and water injection mechanism and indicator curve model for fractured-vuggy carbonate reservoirs

Water injection for oil displacement is one of the most effective ways to develop fractured-vuggy carbonate reservoirs.With the increase in the number of rounds of water injection,the development effect gradually fails.The emergence of high-pressure capacity expansion and water injection technology allows increased production from old wells.Although high-pressure capacity expansion and water injection technology has been implemented in practice for nearly 10 years in fractured-vuggy reservoirs,its mechanism remains unclear,and the water injection curve is not apparent.In the past,evaluating its effect could only be done by measuring the injection-production volume.In this study,we analyze the mechanism of high-pressure capacity expansion and water injection.We propose a fluid exchange index for high-pressure capacity expansion and water injection and establish a discrete model suitable for high-pressure capacity expansion and water injection curves in fractured-vuggy reservoirs.We propose the following mechanisms:replenishing energy,increasing energy,replacing energy,and releasing energy.The above mechanisms can be identified by the high-pressure capacity expansion and water injection curve of the well HA6X in the Halahatang Oilfield in the Tarim Basin.By solving the basic model,the relative errors of Reservoirs I and II are found to be 1.9%and 1.5%,respectively,and the application of field examples demonstrates that our proposed high-pressure capacity expansion and water injection indicator curve is reasonable and reliable.This research can provide theoretical support for high-pressure capacity expansion and water injection technology in fracture-vuggy carbonate reservoirs.

Effect of water extracts of larch on growth of Manchurian walnut seedlings

A study was conducted to detect the effect of water extracts from different parts such as root, bark, branch and leaf, of adult larch, Larix gmelini, trees on growth of Manchurian walnut, Juglans mandshudca, seedlings and the allelopathy between the two tree species. Four concentrations （100 g. kg i, 50 g. kg^-1, 25 g. kg^-1 and 12.5 g. kg^-1） were prepared for each kind of extracts. Result showed that the water extracts with low and moderate concentrations accelerated the growth of collar diameter and increased biomass and root/shoot ratio of walnut seedlings. The water extracts from branches and barks with low and moderate concentrations accelerated the height growth of the seedlings, while those from leaves and roots slightly decreased the height growth of seedlings. The fact that application of water extracts of larch improved the growth of Manchurian walnut attributes possibly to the allelopathy between the two tree species.

Effect of Kaolin Film Particle Applications (Surround WP^®) and Water Deficit on Physiological Characteristics in Rose Cut Plants (<i>Rose spp</i>L.)

The effect of foliar applications of a kaolin clay particle film (Surround WP) on leaf temperature (Tlf), chlorophyll fluorescence (Fv/Fm), shoot length, production and water relations in well-irrigated and water-stressed rose cut plants (Rose spp) were studied during ten weeks. Plants were sprayed twice at first and fifth week after the experiment started with aqueous suspensions of Kaolin (Surround) at a dose of 5% (w/v). The interaction between Kaolin applications and water status did not showed significances. Water stress decreased the stomatal conductance (gs), leaf water content (LWC), shoot length and the number of marketable floral stems. Kaolin sprays did not affect on SPAD readings, chlorophyll fluorescence, gs, LWC and shoot length. Kaolin reduced leaf temperature by 2.5°C approximately at midday compared to plants non-sprayed with kaolin. These results show that kaolin foliar applications could be considered an useful tool at early growth stage in improving rose plant acclimation to high temperatures levels under greenhouse conditions in tropical regions.

Water adaptive traits of deep-rooted C_3 halophyte(Karelinia caspica(Pall.) Less.) and shallow-rooted C_4 halophyte(Atriplex tatarica L.) in an arid region,Northwest China

This paper focused on the water relations of two halophytes differing in photosynthetic pathway, phe- notype, and life cycle： Karelinia caspica （Pall.） Less. （C3, deep-rooted perennial Asteraceae grass） and Atriplex tatarica L. （C4, shallow-rooted annual Chenopodiaceae grass）. Gas exchange, leaf water potential, and growth characteristics were investigated in two growing seasons in an arid area of Xinjiang to explore the physiological adaptability of the two halophytes. Both K. caspica and A. tatarica showed midday depression of transpiration, in- dicating that they were strong xerophytes and weak midday depression types. The roots of A. tatarica were con- centrated mainly in the 0-60 cm soil layer, and the leaf water potential （~L） increased sharply in the 0-20 cm layer due to high soil water content, suggesting that the upper soil was the main water source. On the other hand, K. caspica had a rooting depth of about 1.5 m and a larger root/shoot ratio, which confirmed that this species uptakes water mainly from deeper soil layer. Although A. tatarica had lower transpiration water consumption, higher water use efficiency （WUE）, and less water demand at the same leaf water potential, it showed larger water stress impact than K. caspica, indicating that the growth of A. tatarica was restricted more than that of K. caspica when there was no rainfall recharge. As a shallow-rooted C4 species, A. tatarica displayed lower stomatal conductance, which could to some extent reduce transpiration water loss and maintain leaf water potential steadily. In contrast, the deep-rooted C3 species K. caspica had a larger root/shoot ratio that was in favor of exploiting groundwater. We concluded that C3 species （K. caspica） tapes water and C4 species （A. tatarica） reduces water loss to survive in the arid and saline conditions. The results provided a case for the phenotype theory of Schwinning and Ehleringer on halophytic plants.

Discussion on Anti-Seepage Technologies in the Construction of Small-Scale Rural Water Conservancy Projects

In order to ensure the sustainable growth of rural economy,it is necessary to carry out further research on small-scale water conservancy projects and solve the seepage issue in rural areas.Based on the application significance of small-scale rural water conservancy projects and the analysis of anti-seepage technologies,along with specific examples,this paper specifically discusses the application of high-pressure jet technology,so as to provide reference for the development of engineering construction.

枝条角度对中国沙棘水碳代谢和生长结实的影响

[目的]研究中国沙棘不同角度枝条的水碳代谢与生长结实的关系,深入了解枝条角度对生长结实的影响及其生理机制,为沙棘的高效栽培技术措施的制定提供理论依据。[方法]本研究选择中国沙棘0°、45°、90°、135°4种角度枝条作为研究对象,比较其水势和水分输导能力、光合作用、非结构性碳水化合物、营养生长和花芽分化情况、结实性状以及果实营养成分上的差异,并进一步分析不同角度枝条的水碳代谢和生长结实之间的相互关系。[结果]0°~90°枝条的7月水势无显著差异,135°枝条7月凌晨和正午水势显著低于其它角度。随着枝条角度的增加,7月和9月的枝条PLC均呈升高趋势,枝条叶面积比导水率和茎面积比导水率呈降低趋势。0°~90°枝条的净光合速率差异不显著,135°枝条净光合速率显著低于其它角度。7月枝条NSC含量无显著差异,9月枝条木质部NSC含量呈先升后降的趋势,韧皮部NSC含量随枝条角度的增大而降低。随着枝条角度的增大,叶面积和新梢生长情况均呈降低趋势,比叶重、新梢总数、花芽占比、花芽纵横径、果实纵横经和百果质量、10 cm结果数和总黄酮含量均呈先升后降的趋势,在45°和90°达到较高水平。[结论]随着枝条角度的增加,干旱时期的水分状况变差,枝条营养生长变弱,NSC储藏、花芽分化、结实性状在45°~90°达到较高水平,因此在生产上利用45°~90°枝条结实可以提高中国沙棘产量。

不同防护措施对早熟朱柿抽条的防护效果及其生理机制

选取定植1 a的早熟朱柿幼树为研究对象,设置树干缠防寒布+反光膜、树干培土、树干涂白、树干缠防寒布、枝条喷涂水果保鲜剂、枝条喷涂高脂膜、枝条喷涂石蜡乳化剂共7个防抽条处理,测定不同处理的抽条率以及一年生枝的水分状况、细胞活力和非结构性碳水化合物(NSC)含量。结果表明:防寒布+反光膜处理和培土处理抽条率为0,水果保鲜剂、高脂膜、石蜡乳化剂处理抽条率介于30%~60%之间,涂白、防寒布处理及对照的抽条率为100%。石蜡乳化剂、防寒布+反光膜处理和培土处理的凌晨水势显著高于水果保鲜剂处理和高脂膜处理(P<0.05),两组差值为0.5 MPa左右。培土处理的枝条导水损失率(PLC)较水果保鲜剂处理和高脂膜处理显著降低,分别降低10.95%和11.24%(P<0.05);韧皮部细胞活力显著高于其他处理,增幅为13.53%~34.87%(P<0.05)。培土处理的韧皮部可溶性糖含量、淀粉含量和NSC含量显著高于其他处理,分别提高13.79%~28.80%、9.15%~39.65%和14.87%~29.61%(P<0.05),培土处理的木质部可溶性糖含量、淀粉含量和NSC含量显著高于其他处理,分别提高20.59%~35.27%、14.19%~37.90%和17.40%~37.00%(P<0.05)。相关性分析结果表明,不同防抽条技术措施下的抽条率与枝条PLC呈显著正相关关系(P<0.05),与枝条凌晨水势、木质部相对含水量、韧皮部细胞活力、木质部淀粉含量、木质部NSC含量呈显著负相关关系(P<0.05)。可见,防寒布+反光膜处理和培土处理对柿树冬春季抽条有较好的防护效果,能维持枝条水分状况和韧皮部细胞活力,并促进NSC向枝条运输。

不同土壤水分处理对冬小麦根冠生长的影响

通过温室冬小麦不同水分处理(土壤含水量分别为田间持水量的75%～100%,65%～55%,35%～45%)盆栽试验,研究了冬小麦根冠对水分的响应。试验结果表明:不同供水量并不影响冬小麦根系、冠层干物质累积过程的总趋势,但随胁迫的增强,根、冠干物质累积速率、干物质累积总量降低,且二者并不呈线性相关关系;根冠比(R/S)随胁迫的增强而增大;水分供应量的减少缩短了冬小麦的生育周期,随胁迫的增强,根冠生物量最大值出现的时间提前;充分供水的处理则有最大的根冠比(R/S)。这可能是由于水分胁迫发生,大量的同化产物运往根系,分配于根系的同化干物质增加,调整了根系的结构,改善其功能以增大水分的吸收量,缓减植株由于缺水造成的损失,导致根系干重增加,根冠比增加。对于供水超过75%的植株,根冠比达到所有处理的最大,可能原因为过量水分促使庞大根系的建成,从而消耗较多的同化产物,使根重增加,冠重减少。

水稻拔节期水分胁迫及复水对叶片叶绿体色素的影响

通过盆栽试验,对水稻拔节期不同程度、不同历时的水分胁迫及复水后叶片叶绿体色素含量变化及其机理进行了研究.结果表明:胁迫历时对叶绿体色素的影响大于胁迫程度对叶绿体色素的影响.短历时(5 d)胁迫会增加叶绿素含量,复水后会降低叶绿素含量,且重度胁迫复水后对叶绿素的补偿效应强于轻度胁迫复水后对叶绿素的补偿效应;长历时(10 d)胁迫会降低叶绿素含量,复水后会增加叶绿素含量,且轻度胁迫复水后对叶绿素的补偿效应强于重度胁迫复水后对叶绿素的补偿效应.水分胁迫会增加叶绿素a与b的质量比,复水后会降低叶绿素a与b的质量比.类胡萝卜素含量的变化趋势与叶绿素含量的变化趋势一致.

水氮调控对冬小麦根冠比和水分利用效率的影响研究

通过田间和桶栽试验研究了水、氮调控对冬小麦根冠比和水分利用效率的影响。田间试验结果显示,土壤水分条件对冬小麦根冠生长影响显著。当冬小麦生育期60 cm土层土壤水分维持在田间持水量的60%以上时,根冠比维持稳定状态,不随灌溉次数的增加而变化;当冬小T麦生育期60 cm土层土壤水分低于田间持水量的60%时,土壤越干旱,根冠比越大。桶栽试验结果显示,氮素水平对冬小麦根冠比影响显著,而水氮互作效应对根冠比影响不显著。在所有水分处理条件下,随着施氮量增加,冬小麦根量减少。施氮对冬小麦地上部分和地下部分的影响不同。在水分亏缺条件下,随着氮用量增加,冬小麦经济产量呈增加趋势,水分利用效率与施氮量存在明显正相关关系;而在充分灌溉条件下,产量随着施氮量的增加表现出先增加后降低的趋势,存在一个氮肥用量阈值。因此,水氮通过调控地上地下干物质分配而影响作物产量和水分利用效率,在水分供应受限制条件下,增施氮肥会降低根冠比,更利于地上干物质的积累和经济产量形成。田间试验和桶栽试验均表明,冬小麦根冠比与水分利用效率呈负相关,根冠比大不利于地上部分干物质的积累和作物产量的形成,导致水分利用效率降低。

断根和剪枝对盆栽苹果叶片光合蒸腾及WUE的影响

以 5年生盆栽苹果 (MalusdomesticaBorkh/MalushupenensisRhed)为试材 ,研究了断根和剪枝等处理对叶片净光合速率 (Pn)、蒸腾速率 (Tr)、气孔导度 (Gs)、水分利用效率 (WUE)的影响及引起WUE变化的原因。结果表明 ,断根明显提高了WUE ,处理后第 2～ 42天逐渐升高。同时 ,断根后Tr、Gs明显下降 ,而Pn和羧化效率 (CE)迅速恢复 ,并在第 7天以后明显高于对照 ;新根总数及叶片玉米素核苷 (ZR)浓度则于第 2 8天后恢复至对照水平。剪枝使Pn、CE、Tr、Gs及叶片ZR浓度升高 ,但WUE只在 2 8d后稍高于对照。断根结合剪枝后第 2天 ,Pn、CE、Tr及Gs下降 ;2 1d后Pn和CE高于对照 ,而Tr及Gs与对照相近 ,WUE在后期稍有升高。分析认为 ,断根通过降低气孔导度极显著地提高了叶片WUE ,剪枝则通过提高CE而使WUE升高。

1-MCP处理对脱壳茭白木纤化与细胞结构的影响

研究了不同体积分数1-MCP处理对常温和低温贮藏期间脱壳茭白木纤化以及细胞超微结构的影响。结果发现:0.5μL/L的1-MCP处理可较好保持常温和低温条件下茭肉的外观品质,抑制乙烯的产生,减少纤维素含量的增加,抑制可溶性果胶含量的下降和原果胶含量的增加,减轻茭肉木纤化过程。用透射电镜观察常温贮藏6 d后的茭肉超微结构,发现1-MCP处理的细胞较对照细胞内含物丰富,胞间连丝仍然清晰,证实了1-MCP处理可延缓脱壳茭白的衰老过程。