初始通气对PHD-PVD真空预压法处理淤泥加固影响试验研究

为进一步改善水平联合竖直排水板真空预压法加固效果的影响,提出了PHD-PVD真空预压联合通气法。通过5组室内模型试验,对真空预压过程中的排水量、沉降量、孔隙水压力等进行监测。试验结果表明:间歇通入空气能够使排水通道的水形成回流,润湿周围土体,待重新启动真空泵时,瞬间施加的真空吸力破坏土体的结构,产生更多新的排水通道,提升排水效率。相较于未进行间歇通气的试验组,当抽真空96 h时启动间歇通气,试验后土体的排水量增加9.38%,土体表面沉降增加12.29%,十字板剪切强度提高了22.8%,孔压消散值增加了23.26%,在各组试验中效果最好。该研究为改进真空预压法的技术发展提供了参考依据。

钻探技术在某煤矿井下防治水的应用探究

煤矿开采受开采环境、地势结构等方面的影响。其中水害为较为常见的问题,会导致后期开采工作无法顺利开展。本文针对钻探技术在煤矿井下防治水中的应用展开分析,以先进科学钻探技术为支撑,实现高质量煤矿防治水施工。同时应综合考虑煤矿井下水害类型,合理应用全煤层钻孔螺旋钻杆、高角度上仰孔等多项钻进技术,顺利实现煤矿井下防治水目标。

浅谈排水工程的排水方式

排水不畅造成洪涝等灾害,如洪灾、涝灾、清灾、土壤盐碱化、冷浸田等表现形式。排水工程的内容包括工程 措施和非工程措施,而工程措施有水平和竖直排水。

井下空压机冷却水节能技术研究

针对煤矿井下空压机的实际情况,对循环水和直排水系统进行了分析和比较,并设计了以管壳式热交换器为核心的、与煤矿井下水冷式空压机相配套的循环冷却水冷却系统,在煤矿应用后取得了良好的节能效果。

高炉冷却水处理技术与工艺

在实践的基础上 ,对敞开式高炉冷却水循环系统水处理技术。

A general solution for vertical-drain consolidation with impeded drainage boundaries

An analytical solution is derived from the generalized governing equations of equal-strain consolidation with vertical drains under multi-ramp surcharge preloading. The hydraulic boundary conditions at both top and bottom of the consolidating soil are modelled as impeded drainage. The impeded drainage is described by using the third type boundary condition with a characteristic factor of drainage efficiency. Fully drained and undrained boundary conditions can also be modelled by applying an infinite and a zero characteristic factor, respectively. Simultaneous radial and vertical flow conditions are considered, together with the effects of drain resistance and smear. An increase in total stress due to multi-ramp loading is reasonably modelled as a function of both time and depth. A solution to calculate excess pore-water pressure at any arbitrary point in soil is derived, and the overall average degree of consolidation is obtained. It shows that the proposed solution can be used to analyze not only vertical-drain consolidation but also one-dimensional consolidation under either one-way or two-way vertical drainage conditions. The characteristic factors of drainage efficiency of top and bottom boundaries have a potentially important influence on consolidation. The boundary may be considered fully drained when the characteristic factor is greater than 100 and fully undrained when the characteristic factor is less than 0.1. The stress distribution along depth induced by the surcharge loading has a limited effect on the overall average degree of consolidation.

Stability analyses of vertically exposed cemented backfill:A revisit to Mitchell's physical model tests

Mitchell's solution is commonly used to determine the required strength of vertically exposed cemented backfill in mines. Developed for drained backfill, Mitchell model assumed a zero friction angle for the backfill. Physical model tests were performed. Good agreements were obtained between the required strengths predicted by the analytical solution and experimental results. However, it is well-known that zero friction angle can only be possible in terms of total stresses when geomaterials are submitted to unconsolidated and undrained conditions. A revisit to Mitchell's physical model tests reveals that both the laboratory tests performed for obtaining the shear strength parameters of the cemented backfill and the box stability tests were conducted under a condition close to undrained condition. This explains well the good agreement between Mitchell's solution and experimental results. Good agreements are equally obtained between Mitchell's experimental results and FLAC3 D numerical modeling of shortterm stability analyses of exposed cemented backfill.

In Situ Tests--Predicted vs. Observed Settlements： A Comparative Case Study

This paper aims to deal with the comparison of the estimated settlements derived by in situ tests with the observed settlements in site, in order to evaluate the accuracy of settlement prediction by in situ tests, in comparison not only with site observation by topographic means, but also with the values of settlements derived by numerical analysis by means of PLAXIS 2D and 3 D. The site where are carried out the tests and periodically are observed the settlements since the beginning of construction process, is located in the Oil Product Terminal, at the industrial park of Porto Romano, Durres, Albania. The main purpose of this project was the ground improvement by using preloading method in order to prevent liquefaction process and settlements. The data used to conduct this study are taken by the site investigation done after inserting into the soil vertical drains made of columns of free--draining gravel （gravel pile drains） until 14 m depth and center-to-center spacing of 2 m, and wick drains （premanufactured） until 25 m depth and center-to-center spacing of 1.8 m. The observed settlements are periodically measured by topographic equipments. This paper will present the conclusions derived by settlement analyzes from in situ tests and site observations.

Indirect Watermarking

Watermariding system is a complex system requiring both expertise and specialized techniques with security concems.Thus to relieve the multimedia manufactures of the complexities of desgning complicated watermarking systems,this paper presents a new watermarking model in which watermaiking is provided as a kind of service by the specialized watermarking companies.In order to make this service model work,a simple permutation scheme to hide the true contents is proposed.The paper also proves the security of the scheme against the attacks from the watermarking companies.Finally ,the effectiveness of the scheme is demonstrated through experiments.

Sensitivity of Chinese Industrial Wastewater Discharge Reduction to Direct Input Coefficients in an Input-output Context

Industrial wastewater discharge in China is increasing with the country′s economic development and it is worthy of concern. The discharge is primarily relevant to the direct discharge coefficient of each sector of the economy, its direct input coefficient and the final demand in input-output models. In this study, we calculated the sensitivity of the reduction in the Chinese industrial wastewater discharge using the direct input coefficients based on the theory of error-transmission in an input-output framework. Using input-output models, we calculated the direct and total industrial wastewater discharge coefficients. Analysis of 2007 input-output data of 30 sectors of the Chinese economy and of 30 provincial regions of China indicates that by lowering their direct input coefficients, the manufacturers of textiles, paper and paper products, chemical products, smelting and metal pressing, telecommunication equipment, computers and other electronic equipment will significantly reduce their amounts of industrial wastewater discharge. By lowering intra-provincial direct input coefficients to industrial sectors themselves of Jiangsu, Shandong and Zhejiang, there will be a significant reduction in industrial wastewater discharge for the country as a whole. Investment in production technology and improvement in organizational efficiency in these sectors and in these provinces can help lessen the direct input coefficients, thereby effectively achieving a reduction in industrial wastewater discharge in China via industrial restructuring.

Vertical drainage capacity of new electrical drainage board on improvement of super soft clayey ground

As an advanced polymer composites electro-kinetic geosynthetics, the electro-osmotic vertical drainage(EVD) board could drain water quickly and accelerate consolidation process. However, the drainage rate was mainly impacted by the vertical drainage capability. Therefore, vertical drainage capability at the top of EVD board was theoretically analyzed. Basic requirements for drainage at the top of the board were summed up, as well as the formula of anode pore pressure when losing the vertical drainage capability. Meanwhile, a contrast test on the top and bottom drainage capacities was conducted. In use of the advanced EVD board, the voltage potential and pore pressure of anode were measured. Moreover, the derived formulas were verified. The result shows that the decrease of electric force gradient had an observable impact on the drainage capability. There was nearly no difference between the energy consumption for the two drainage methods. Although a little less water was discharged, the top drainage method had more advantages, such as high initial drainage velocity, few soil cracks, low anode water content and high soil strength. All of these show that the super soft soil ground could be consolidated quickly in use of the advanced EVD board through the top drainage. The top drainage method could efficiently improve the drainage effect, decrease the energy consumption and speed up the project proceeding.

含水量变化对广州花岗岩残积土抗剪强度的影响

基于不固结不排水直剪试验,建立了广工大学城区域花岗岩残积重塑土关于含水率与抗剪强度指标之间的试验曲线。试验研究表明:在控制相同含水量与干密度条件下,对花岗岩残积原状土和重塑土进行了不固结不排水直剪试验,当垂直压力小于先期固结压力时,重塑土的粘聚力小于原状土的粘聚力,重塑土的内摩擦角也小于原状土的内摩擦角;当垂直压力大于先期固结压力时,两者的抗剪强度逐渐接近,且在垂直压力大于135 kPa之后,原状土的抗剪强度小于重塑土的抗剪强度,此时重塑土的内摩擦角大于原状土的内摩擦角。在不同含水量的花岗岩残积重塑土不固结不排水直剪试验中,土体的抗剪强度均随垂直压力的增大而增大;土体的黏聚力随含水率的增加而显著减小,而内摩擦角随含水率的增加而稍微减小。