APPLICATION OF TIME-VARYING VISCOUS GROUT IN GRAVEL- FOUNDATION ANTI-SEEPAGE TREATMENT

The time-varying viscosity of common grout and the controllable grout are measured with a rotation viscometer in experiments.The time-varying viscosity of grout is analyzed according to the characteristics in the process of anti-seepage treatment for gravel foundation.The principle of effective stress for porous medium is applied to analyzes the fluid-structure coupling in grouting.In the consideration of coupling physical variables,dynamic models of porosity,permeability and viscosity are constructed.The diffusion radius can thus be defined by the foundational porosity.The distribution of holes in field experiments is designed according to the diffusion radius of grout.Then,the permeability test is designed to verify the grout effect.The calculated diffusion radius coincides with experimental results,and the permeability meets the requirements of the project,which is valuable for the anti-seepage treatment in gravel foundation.     

砂砾石灌浆在虎头咀泵站围堰防渗中的应用

文章阐述了靖远电厂二期虎头咀泵站围堰防渗工程地质条件、技术参数、过程控制等,通过防渗效果分析,认为围堰防渗中达到了预期目的,表明砂砾石灌浆技术在靖远电厂二期虎头咀泵站围堰防渗工程应用取得了成功,可在类似工程中推广应用.     

人工砂中的石粉含量对水工混凝土性能的影响

文章分析了人工砂中不同石粉含量对水工混凝土中新拌混凝土的影响(包括坍落度、含气量),以及对抗压强度、抗冻性和抗渗性的影响.通过各项试验表明,人工砂中随着石粉含量的增加,混凝土的含气量、坍落度不断减小;当人工砂的石粉含量为16％时,硬化混凝土的抗压强度、抗冻性、抗渗性达到最佳效果.     

Large wood aids spawning Chinook salmon (Oncorhynchus tshawytscha) in marginal habitat on a regulated river in California

To determine whether large wood (LW, ≥1‐m length, ≥10‐cm diameter) plays a role in Chinook salmon (Oncorhynchus tshawytscha) redd (i.e. egg nest) placements in a regulated, Mediterranean‐climate, medium‐sized river (where channel width is less than the upper quartile of length of potential instream wood pieces), characteristics of 527 large wood pieces, locations of 650 redds, and mesohabitat delineations (riffle, run, glide, pool) were collected during a spawning season along a 7.7 km reach directly below Camanche Dam on the Mokelumne River, CA. LW was regularly distributed across the study reach an average 70 LW pieces km^‐1. Some LW clustering was evident at islands and meander bends. Spawners built 85% of redds within one average channel width (31 m) of LW. Spawners utilized LW within a 10 m radius 36% of the time in the upper 3 km rehabilitated reach, and 44% of the time in the lower 4.7 km marginal habitat reach. A greater percentage of LW was utilized in riffles in the upper 3 km reach where 90% of redds were built, while a larger percentage of spawners used LW in riffles in the lower 4.7 km reach. LW‐redd interactions occurred at greater rates than by random chance alone in the lower 4.7 km reach, which implies that LW aids spawning in marginal habitats. River managers and salmonid spawning habitat rehabilitation (SHR) projects should take LW additions into consideration as an important component of river rehabilitation. Copyright © 2010 John Wiley & Sons, Ltd.     

Geomorphic comparison of two Atlantic coastal rivers: Toward an understanding of physical controls on Atlantic salmon habitat

River channel substrate size and mobility are important to Atlantic salmon spawning and rearing success. We compare morphology and bed sediment between two North American Atlantic coastal streams (Narraguagus River, Maine, USA and Jacquet River, New Brunswick, Canada). The watersheds have similar drainage areas and mean annual precipitation, but differing relief structure, channel longitudinal profiles and numbers of returning salmon. The lower‐relief Narraguagus River is segmented into steeper (gradient >0.002) and flatter reaches (gradient <0.0005). Flat reaches, including mainstem lakes, act as sediment sinks, preventing the continuity of downstream sediment transport. Based on field measurements, the Narraguagus River has a larger high‐flow width to depth ratio than the Jacquet River, but this difference is principally the result of outliers from low‐gradient channel reaches. Measurements of substrate grain size reveal finer river‐bed sediments on the Narraguagus River, however, Shields parameter calculations indicate that bed sediment should be mobile during high flows in both streams. We use the Shields equation to predict grain size based on channel slope, width and drainage area measured from digital elevation models (DEM) and aerial photographs. Predictions of median grain size agree with field measurements within a factor of 2 for 62–70% of the survey stations. We suggest ways that model misfits may provide opportunities to prioritize reach‐based restoration efforts. Based on expected grain size, we estimate 62% spawning and 68% rearing habitat along the length of the Narraguagus River, and 28 and 95% respectively on the Jacquet. Overall, glacial history and relief structure appear to be the first‐order controls on substrate grain size and habitat quality in these two rivers. Copyright © 2010 John Wiley & Sons, Ltd.     

石拱桥拱圈加固的约束机理分析

通过分析套箍和砌体横向应变关系,探讨了采用钢筋昆凝土套箍加固石拱桥对核心砌体的约束机理,并提出了套箍对核心砌体的约束应力及由于套箍约束作用使砌体强度提高的计算方法.同时,通过此方法对巴中市南江县龙渠大桥进行了加固设计,计算后得知主拱圈承载力得到明显提高,且实际运用效果良好.     

强风化千糜岩粉土改良的CBR试验研究

由于强风化千糜岩风化程度强,微裂纹发育,强度很低,在开采、运输、摊铺、碾压和整平过程中颗粒破碎严重,最终成粉土状。用作高速公路路堤填料时,出现了填料压实不足,承载力偏低,弯沉值不满足设计要求,雨后沉降量过大等不利病害,因此,对强风化千糜岩粉土采用了掺加2%、3%、4%、5%的水泥和掺加砂砾与粉土比例为2∶8,3∶7,4...     

一种融合分水岭与ISODATA的岩心图像分割方法

分水岭算法用于图像分割,能获得封闭的和位置准确的轮廓,但容易造成过分割;ISODATA算法能将岩心砾石颗粒聚集成一类,但会使砾石目标边缘位置漂移。为克服以上两种方法的缺点,提出融合分水岭和ISODATA的图像分割方法。该方法首先利用分水岭算法得到过分割图像,ISODATA算法得到聚类图像,然后以ISODATA算法聚类的结果为依据,校正分水岭法的过分割问题。该方法用于砾岩图像的分割,取得了较好的实验效果。     

川南石刻图像模板匹配方法研究

本文以四川南部地区南宋墓葬石刻艺术图像为切入点,提出石刻图像模板匹配的方法,重点讨论石刻图像模板匹配的具体方法与流程,以及匹配过程中需要解决的几个关键技术性问题,最后通过仿真实验证明了该方法的有效性,并指出进一步的研究方向.     

川南石刻图像特征提取方法研究

本文以四川南部地区南宋墓葬石刻艺术为切入点,提出石刻图像特征提取的具体方法,并通过仿真试验证明了该方法的有效性,最后指出了进一步的研究方向.