对“论土骨架与渗透力”讨论的答复

拜读毛昶熙老先生对拙作的批评意见,甚为感动。毛先生年事已高,头脑仍然清晰敏锐,并不吝指教,指出文章中的谬误与不足。对笔者而言,＂就有道而正焉＂,不亦乐乎。回答与请教如下,敬请指正。1关于土力学中的虚拟尽管土力学跻身于力学,但由于其对象的特殊性及工程实践的复杂性,实用主义的倾向是很突出的。

滤水排渗桩在堤防渗漏险情抢护中的研究与应用

1成果技术介绍1.1技术原理借鉴“基坑井点”排水原理,加工制造滤水管桩。在抢护堤防渗漏险情时,只需将滤水排渗管桩直接置入堤防渗漏区范围堤身内部,抽排管内气体,致使滤水管内形成真空,再加上堤防堤身或地基渗透水压力的作用,渗透水流经过滤料过滤能够快速将清水通过滤水段过滤管和排水嘴排出堤身或地基以外,从而避免堤身发生渗水、流土、滑坡和地基发生管涌等渗透破坏险情发生。

无砂混凝土板取水工程渗流渗透特性试验研究

无砂混凝土板取水具有较高的技术经济性,且对改善局部地区地质、水域环境有积极作用。文章共设计三种实验方案,对不同工况下的无砂混凝土板取水容重-工作水头-渗水量关系以及集水公式等进行探讨。研究结果表明,无砂混凝土板取水板容重越大,工程渗流量越小;对单一骨料而言,粒径越小,无砂混凝土板取水板渗水量越小;对骨料进行排列组合时,应尽可能将中骨料、粗骨料铺设至水流下行方向。

A、B反渗透防爆膜破裂原因分析

本文通过对反渗透设备产水流量突降进行了一系列的原因分析,从运行方式、水质变化、产水压力波动、防爆膜材质等方面详 细阐述了可能引起防爆膜破裂的可能性因素及判断过程,并提出了运行和检修方面保障措施。为反渗透设备运行和机组正常补水提高了可 靠性。

某闸测压管实测数据分析及安全稳定验算

根据测压管观测资料不仅能反应出闸上游段的防渗效果和下游逸出点的反滤效果,而且能为闸在运行期间的安全稳定验算提供可靠的数据。本文根据观测成果分别绘出了水闸上游和下游水位与渗透压力曲线,进行了测压管渗透压力特征分析和水闸安全稳定计算。对利用测压管观测成果,分析水闸的运行是否安全稳定具有一定的现实意义。

无纺土工织物的淤堵分析

一、前言土工织物由于其良好的水力特性而广泛应用于排水和反滤系统中。用于反滤的主要作用是在保证透水的前提下,防止土颗粒的过量流失,造成管涌现象。因此作为理想的反滤系统的土工织物,应能同时满足上述两个相互矛盾的功能。土工织物的水力特性主要取决于孔隙率、渗透性、开孔面积率和孔径等因素。

土工合成材料的应用

土工合成材料(Geosynthetics)是近二三十年发展起来的一种新型土工材料,它具有用途多、施工方便和造价便宜等优点,因而在水利电力、铁道、公路、建筑、海港以及治金等工程中得到了广泛的应用,推动岩土工程在设计理论和施工工艺方面发生了革命性的进展,所发挥的经济效益与社会效益也越来越为人们注目。现对这种新型材料作一简要介绍,以期有助于进一步推广使用。

试论土石坝隐患探测

土石坝在长期复杂的自然环境条件影响和各种内外力的作用下,其状态随时都在变化,有可能产生这样那样的隐患.如果再加上人为因素的影响,如设计考虑不周。

人工湖体开挖反滤层带施工工法

1.前言 当土中水流过土工织物时,水可以顺畅穿过,而土颗粒却被阻留的现象称为反滤。反滤层是指由1层土工布以及3层颗粒大小不同的黄砂、碎石和块石材料铺筑成的,顺着水流的方向颗粒逐渐增大,任一层的颗粒都不允许穿过相邻较粗一层的孔隙,

浅谈燃煤电厂贮灰场设计

随着电力工业的迅速发展,国家每年都要新建和扩建一大批燃煤电厂。目前条件下燃煤电厂一般都需要修建贮灰场,一座40万kw的燃煤电厂,一年排出十几万m^3的灰进入贮灰场。据资料分析,贮灰场每贮存1m^3的灰,需要投资9～11元的工程费用。

有效应力或总应力的分析与稳定安全系数——关于《辗压式土石坝设计规范》SDJ-218-84中“稳定计算”部份的一些问题的讨论之四

在“园弧滑动稳定计算公式——关于《辗压式土石坝设计规范》SDJ——218——84中稳定计算部份的一些问题的讨论之一”的一文中已述及不论计算的是施工期、稳定渗流期或水库水位降落期,都可以按两种具体计算方式,统一地用总应力分析式或有效应力分析式表达稳定计算方程式.对于重力渗流场中的渗透水流作用力,两分析式也都以不同的方式予以计入.这些计算稳定安全系数的方程式,在已考虑坝坡外水位的影响下可表达为:

Energy Recovery Device with a Fluid Switcher for Seawater Reverse Osmosis System

Energy recovery device （ERD） is an important part of the seawater reverse osmosis （SWRO） desalination system. There are principally two kinds of ERDs, the centrifugal type and the positive displacement （PD） type. The PD type is of extensive concern and is preferred in large-scale plants. In this article, an innovative fluid switcher was presented and a two-cylinder hydraulic energy recovery unit with a lab-scale fluid switcher was set up. Tap water was used as the working medium instead of the actual seawater and brine in SWRO desalination plants. Under steady state operating conditions, the experimental results were obtained on the variations of the pressure and flow rate to and from the energy recovery unit. The hydraulic recovery efficiency （En） of the energy recovery unit with the fluid switcher reached up to 76.83%.

Pore-scale simulation of gas-water flow in low permeability gas reservoirs

A novel method was developed to establish a realistic three dimensional(3D) network model representing pore space in low permeability sandstone.Digital core of rock sample was established by the combination of micro-CT scanning and image processing,then 3D pore-throat network model was extracted from the digital core through analyzing pore space topology,calculating pore-throat parameters and simplifying the shapes of pores and throats.The good agreements between predicted and measured porosity and absolute permeability verified the validity of this new network model.Gas-water flow mechanism was studied by using pore-scale simulations,and the influence of pore structure parameters,including coordination number,aspect ratio and shape factor,on gas-water flow,was investigated.The present simulation results show that with the increment of coordination number,gas flow ability in network improves and the effect of invading water on blocking gas flow weakens.The smaller the aspect ratio is,the stronger the anisotropy of the network is,resulting in the increase of seepage resistance.It is found that the shape factor mainly affects the end points in relative permeability curves,and for a highly irregular pore or throat with a small shape factor,the irreducible water saturation(Swi) and residual gas saturation(Sgr) are relatively high.

Rules for confidence intervals of permeability coefficients for water flow in over-broken rock mass

Based on the steady-state seepage method, we used the Mechanical Testing and Simulation 815.02 System and a self-designed seepage instrument for over-broken stone to measure seepage properties of water flows in three types of crushed rock samples. Three methods of confidence interval in describing permeability coefficients are presented: the secure interval, the calculated interval and the systemic interval. The lower bound of the secure interval can be applied to water-inrush and the upper bound can solve the problem of connectivity. For the calculated interval, as the axial pressure increases, the length of confidence interval is shortened and the upper and lower bounds are reduced. For the systemic interval, the length of its confidence interval, as well as the upper and lower bounds, clearly vary under low axial pressure but are fairly similar under high axial pressure. These three methods provide useful information and references for analyzing the permeability coefficient of over-broken rock.

Osmotic concentration of succinic acid by forward osmosis:Influence of feed solution pH and evaluation of seawater as draw solution

In this study, we investigated the essential role of feed solution pH so as to gain insights into the transport mechanisms of succinic acid concentration by osmotically-driven forward osmosis （FO） process. FO performances including water flux and bidirectional transport of succinate and chloride anions were systematically examined using cellulose triacetate-based FO membrane. Additionally, real seawater was explored as draw solution. Experimental results revealed that the pH-dependent speciation of succinic acid can affect the FO performances. Ionization of succinic acid at higher solution pH enhanced the osmotic pressure of feed solution, thus leading to lower water flux performance. A strong effect was pointed out on the succinate rejection for which nearly 100% rejections were achieved at pH above its pKa2 value. The rejection of succinate increased in the following order of chemical form： C2H4C2O4H2 〈 C2H4C2OH- 〈 C2H4C2O24-. With real seawater as the draw solution, low to moderate water fluxes （〈4 L. m- 2. h- 1 ） were observed. The divalent succinate anion was highly retained in the feed side despite differences in the succinic acid feed concentration at pH of approximately 6.90.

Influence of Temperature on the Performance of Forward Osmosis Using Ammonium Bicarbonate as Draw Solute

This study investigated the influence of temperature on the performance of forward osmosis(FO) under the condition that the feed solution(FS) temperature was diff erent from draw solution(DS) temperature. An FO model considering the mass and heat transfer between FS and DS was developed, and the FO experiment with ammonium bicarbonate solution as DS and sodium chloride solution as FS was carried out. The predicted water flux and reverse draw solute flux using the developed model coincided with the experimental fluxes. Increases in the temperature of FS or DS yield corresponding increases in the water flux, reverse draw solute flux, and forward rejection of feed solute. Compared with increasing the FS temperature, increasing the DS temperature has a more significant impact on enhancing FO performance. When the temperature of DS increased from 20 to 40 ℃, the specific reverse solute flux decreased from 0.231 to 0.190 mol/L.

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.

On-site tests to estimate aquifer permeability of drainage area of south caisson anchorage construction of Taizhou Bridge

During the construction of the south caisson anchorage of Taizhou Bridge, the drainage area is located in the lower reaches of the Yangtze River and the permeability of stratums there is considerable. In order to maintain progress and guarantee safety during the sinking of the caisson, water should be drained in the initial period. Subsequently, detailed information about the aquifer permeability is required to make sure that the drainage will proceed successfully, which consequently necessitates the on-site estimation of the aquifer permeability in the drainage area. Therefore, the traditional pumping test and slug test are implemented respectively on site. The comparison of computational results of these two tests indicates that they are consistent overall. Notwithstanding, as slug test can be conducted with portable facilities in a short time and the manipulation is easy and few people need to be involved, the advantages of slug test is conspicuous compared with the traditional pumping test. It could be speculated that slug test will gain a prevalent application in the measurement of aquifer permeability in the future.