Swelling behavior induced by alteration in granite and its implications on underground excavation

Granite is commonly recognized as an ideal medium for underground construction. However, in the site investigation for Heimifeng Pumped Storage Power Station project, it was found that there are swelling behaviors induced by alteration in granite and eventually causing slaking and disintegration of rock blocks. The study shows that hydrothermal alteration in granite is primarily due to the intrusion of multi-phase igneous magma. The clay minerals, such as montmorillonite, chlorite, kaolinite, are the main causes for the swelling behavior of granite. In the exploratory adits, alteration was observed to occur mainly along faults or fractures in the rock masses and resulted in roof caving if water is present. Some of the highly altered borehole cores swell and crack within 24 h in water and eventually disintegrate completely. From the testing results on the samples, the maximum axial free swelling strain is about 1.2%, while the maximum axial confined swelling strain is around 0.1% with swelling stress less than 25 kPa. Under free swelling tests, 80% of swelling is completed within 24 hours. Under confined swelling condition, swelling process is completed within 1 h for some samples, with 80% of maximum swelling strain finished within around 22 h for most of the samples. Contraction of samples occurs after swelling completed. The strength of granite, reflected by deformation and elastic moduli, shear strength, decreases due to alteration. The deformation and elastic moduli are even lower compared to highly weathered rock. The shear strength is between that for highly weathered and slightly weathered rocks. The swelling characteristics of the altered rock present great challenges for support or lining during construction and operation stages. Support or lining shall be in place immediately after excavation. Since the rock may swell when encountering water, the shotcrete shall be designed accordingly. During the construction of access tunnel and caverns, water shall be drained in time. Drainage directly from surface shall be avoided so as to prevent floor heave.     

任意层互连生产技术研究

任意层互连（ELIC）是最高阶的高密度连接（HDI）制程，它可以比传统线路在层数相同的情况下，增加约30%层间互连；随着移动通讯产品功能需求的增加，ELIC技术被大举应用在智能手机及平面电脑等产品上。高阶ELIC线路板的生产不但流程长，且生产难度较大。本文对ELIC板的制作难点进行了分析，并提出相应的解决方法和生产注意事项，为ELIC工艺产业化提供必要的参考依据。     

Improvement of gold electrode conductivity after cofiring with CaO–B2O3–SiO2 green tapes for LTCC application

The cofiring process of Au paste containing various amount of glass additive with different properties and CaO–B₂O₃–SiO₂ (CBS) green tapes was investigated. The initial shrinkage temperature of Au paste was strongly associated with the softening point and the content of glass additive. The swell of sample and its mechanism during cofiring process was reported. The sheet resistivity of Au electrode was greatly depended on the content of CBS glass additive. When the content of CBS glass additive with the softening point of 704 °C was 3 wt %, the Au electrode exhibited the highest conductivity with the sheet resistivity of 2.4 mΩ/sq. The results obtained in this paper revealed the relationship between the glass additive and cofiring defects of Au electrode in the metal/ceramic multilayer structure, which gave an avenue to manufacture Low temperature co-fired ceramics (LTCC) modules with good quality.     

抗高温纤维强化凝胶颗粒堵漏剂

井漏是钻井过程中常见的复杂难题,针对常用聚合物凝胶堵漏剂抗温性能差、承压封堵能力弱的问题,通过分子结构设计,以丙烯酰胺、甲基丙烯酸丁酯和2-丙烯酰氨基-2-甲基丙磺酸为单体,柔性纤维为强化材料,过硫酸铵为引发剂,通过与自制大分子交联剂BWL聚合反应,制备了一种新型抗高温纤维强化凝胶堵漏剂。研究了柔性纤维对凝胶堵漏剂流变性能的影响,通过扫描电镜、热重、承压堵漏实验等对凝胶堵漏剂的微观结构、热稳定性、吸水膨胀性和承压堵漏性能进行了研究。结果表明：柔性纤维增强了凝胶堵漏剂的空间网架结构,使其韧性更强;凝胶堵漏剂颗粒具有良好的热稳定性和吸水膨胀性,通过“吸水膨胀、挤压充填”的堵漏原理对漏失通道进行封堵,在140℃下对高渗透性漏失层的封堵承压高于7 MPa,对宽裂缝漏失通道封堵后承压高于5 MPa,可满足高温高压漏失地层中堵漏目的。     

Characterization of electrical sags and swells using higher-order statistical estimators

This paper deals with the detection of power quality anomalies which preserve the frequency of the power line, in particular sags and swells. Three statistical estimators have been used (variance, skewness and kurtosis) to enhance characterization of these anomalies. The proposed measurement strategy is funded in the tuning of the signal under test via a sliding window over which computation is performed. Then, the calculation of the statistical features reveals the inherent properties of the signal: amplitude, frequency and symmetry. The work primarily examines a number of synthetics in order to extract the theoretical statistical features. Then the algorithm is corroborated using real-life signals, obtaining an accuracy of 83%. This experience is part of the design of an instrument for the measurement of the power quality.     

三维气藏预测描述技术在陈家庄凸起天然气勘探中的应用

三维气藏预测描述技术是建立在亮点技术基础之上,结合精细地质研究,综合应用AVO、反射波多参数提取与识别、亮点分析、三维可视化等技术来识别含气储层,从而描述气藏展布。该技术突破了以往应用二维资料描述的孤立豆状气藏的局限,展现了气藏在三维空间的立体分布。在陈家庄凸起勘探中应用了该技术,取得了较好的效果,钻井成功率达96%,较以往提高了12%,完钻的24口井共钻遇气层30层110.2m,年生产能力达20×104m3/d。     

一次法混炼胶在半部件工序中的应用

通过一次法混炼(SSM)混炼胶在轮胎半部件各工序的使用,从流动性、膨胀系数、生热等方面,详细阐述了SSM混炼胶在使用性能上与普通混炼胶的差异。现场实践及数据收集和分析表明:SSM胶料在压出时胶料呈现出的膨胀率小,尺寸前后波动小;拉断强度、定伸强度大。SSM混炼胶混炼时对分子间力破坏小,门尼黏度高但是流动性好,胶料性能稳定,且生热较低。     

Analyse du comportement d’un sol argileux sous sollicitations hydriques cycliques

Expansive soils swell and shrink regularly when subjected to moisture changes. Clayey soils are available worldwide and are a continual source of concern causing substantial damage to civil engineering structures. Cyclic expansion and shrinkage of clays and associated movements of foundations may result in cracking and fatigue to structures. In France, the damage caused by this phenomenon was estimated to be more than 3.3 billion euros in 2002 (Vincent in 3^ème conférence SIRNAT-Forum des journées pour la Prévention des Risques Naturels, Orléans, janv. 2003) and the Paris region is one of the most affected. The objective of this study is to investigate the swell–shrink behaviour of a natural clayey soil considered to be responsible for a lot of damage observed on buildings in the Paris region, and thus contributing to the characterisation and understanding of expansive clayey soils. The studied soil, Argile verte de Romainville, is a lagoonal-marine deposit and is part of the Paris Basin Tertiary (Oligocene) formations (Fig. 1). It is a clayey soil sampled in the eastern region of Paris. The mineralogical and geotechnical properties of the soil are presented in Table 1. The soil contains quartz (15–20%), carbonates (12–20%) and traces of mica and feldspars. X-ray diffraction showed that carbonates are essentially dolomite and the clay minerals are dominantly illite, kaolinite and a small amount of smectite (Fig. 2). A grain size analysis shows that the clay content (<2 μm) varies between 78 and 80%. The study of its microstructure by means of the scanning electron microscope indicates that the clayey soil has structural elements oriented in the direction of bedding. The structure of the sample generally consisted of dense and continuous clay matrices with very limited visible pore spaces (Fig. 3). At its natural water content (w = 25%), the soil shows mainly a unimodal pore size distribution with an average pore radius of 0.07 μm and a very limited porosity with radii larger than 10 μm (Fig. 4). To assess the effect of suction on the simultaneous changes in void ratio and degree of saturation under zero external stresses, drying–wetting tests are performed on the natural samples. The osmotic technique (Polyethylene glycol solutions) and various salt solutions are used to control the suction values ranging from 1 to 300 MPa. Once equilibrium is reached at the given suction, the samples are weighed and their volume is measured. A synthesis of the drying–wetting paths is given on Fig. 5. The swelling potential of the soil is evaluated using both indirect (or empirical methods Tables 2 and 3) and direct methods. Swell percentage and swell pressure of the soil are measured in a conventional oedometer apparatus according to ASTM (D 4546-85). The test specimens are 70 mm in diameter and the height varies between 12 and 24 mm. The swell percentage is measured under a nominal pressure of 0.7, 2.0 and 6.3 kPa. Swelling pressure of the soil is measured by the conventional consolidation test method (free swell and load, ASTM D 4546-85 method A) and by a constant volume method (ASTM D 4546-85 method C). The test parameters and results for each specimen are given in Tables 4 and 5, and on Fig. 7. Cyclic swell–shrink tests are carried out on similar samples taken from the same monolith. A scheme that permits the study of the clayey soil behaviour at the extreme states of wetting and drying is chosen. The test begins by wetting the samples at their natural moisture content and density. When swelling is stabilized, the water is removed from around the samples and they are dried in an oven maintained at 45°C until the vertical deformation (shrinkage) is stabilised and are then rewetted and so on. Some experiments are stopped at different swelling phases for microstructural study of the soil. The test parameters of the specimens are given in Table 9 and the results are shown in Figs. 9 and 10. The evolution of the microstructure during wetting and drying cycles is investigated using scanning electron microscope and mercury intrusion porosimetry. Observations are made only on soil specimens taken at the end of the swelling phase of the selected cycles. In order to preserve the microstructure, the specimens are cut in small pieces, frozen by liquid nitrogen and finally sublimated. The results of the drying–wetting path including the water retention curve are shown on Fig. 5. The results show that on the drying path (in the void ratio versus water content plane) the soil first follows nearly the saturation line and then, as the water content decreases, the void ratio tends towards a constant value. A shrinkage limit of w = 14.5 % and a corresponding suction value of 15 MPa is deduced from this path. An air entry value of 10 MPa is obtained from degree of saturation versus suction curve. The wetting path shows that the wetting–drying path is reversible for suction values higher than 60 MPa. The different indirect methods used to assess the swelling potential of the Argile verte de Romainville show a general agreement with respect to its swelling potential ranging from high to very high (Table 3). Examination of the free swell test results shows that the Argile verte de Romainville exhibits swell percentage in the range of 15–26% and that its degree of swelling depends on the initial conditions (water content, dry density) and the applied load (Table 4). The higher the water content and the applied load, the lower the swell percentage. A specimen taken parallel to the bedding plane shows similar values of swell percentage with a steep volume change versus time curve indicating an anisotropy of permeability. The two direct methods used to assess the swelling pressure of the Argile verte de Romainville give different values (Table 5). The values obtained by the constant volume method are relatively close and are about 700 kPa. Lower values varying between 360 and 540 kPa are obtained by the conventional consolidation test (free swell-consolidation). This indicates that besides the initial conditions, the swelling pressure is strongly dependent on the stress path followed. The results obtained from the wetting–drying cycle tests show that the magnitude of the first swell cycle is controlled by the initial water content, the maximum deformation occurring on the second cycle and the stabilization of swelling deformation from the third cycle (Figs. 9, 10). Furthermore, the experimental data indicate that upon repeated wetting and drying, the swelling rate of the soil becomes faster, which is explained by an increase in permeability of the soil due to the development of preferential flow paths (micro cracks) on drying. With an increasing number of cycles, a permanent increase in the volume of the samples is observed. This suggests that the swelling–shrinkage behaviour of expansive soils is not completely reversible. Mercury intrusion porosimetry analysis and SEM observations before and after different numbers of cyclic swelling indicate that the swelling–shrinkage cycles are accompanied by a continual reconstruction of the soil structure (Figs. 11, 12). The mercury intrusion porosimetry results show that with an increasing number of wetting–drying cycles the pore volume and the average diameter of the pores increase progressively (Fig. 11). Larger modifications are observed in the pores with radius in the range of 0.1–5 μm. SEM observations also show further destruction of large aggregates and disorientation of structural elements as the number of cycles increases (Fig. 12). After the fifth cycle, the soil original structure is totally lost and a disoriented homogeneous and loose structure with more homogeneous pore spaces is observed (Fig. 12d).      

三氯氧磷交联木薯淀粉颗粒膨胀历程及溶胀机理研究

利用木薯淀粉与三氯氧磷的交联反应,通过控制交联反应程度,成功地控制了交联淀粉颗粒的膨胀并使其停留在不同的溶胀阶段,详细地研究了处在不同溶胀阶段的三氯氧磷交联木薯淀粉颗粒的结构特征和变化趋势,揭示了三氯氧磷交联木薯淀粉颗粒的具体的膨胀历程及溶胀机理,即木薯淀粉是“花蕾绽放式”膨胀历程。     

抗渗混凝土膨胀无缝加强带在施工中的应用实例

本文介绍超长结构膨胀无缝加强带施工的基本原理,通过日照市岚山区无害化垃圾处理场工程渗沥液调节池工程实例说明了在超长无缝抗渗混凝土膨胀无缝加强带替代后浇带的技术要点。