Palaeoclimate,stratigraphy and prehistory in north and west Rajasthan

Quaternary formations in western Rajasthan are of fluvial, locustrinal and aeolian origins. Fossil gravel ridge of Jayal in Nagaur District is one of the earliest quaternary formations so far recorded in the region. A rich lower palaeolithic habitation-cum-workshop site has been discovered in association with the gravel ridge. Multiple evidence for climatic change in the area during the quaternary period is discussed.     

A casting procedure for reproducing coarse‐grained sedimentary surfaces

In the ?eld, the measurement of near‐bed hydraulics remains problematic. Greater precision is possible in the laboratory, but, in the case of gravels, it is dif?cult to create a water‐worked channel‐bed that is realistic enough to replicate faithfully the conditions found in nature. In this paper, a technique to reproduce coarse‐grained sedimentary fabrics of large areal extent is described. It involves moulding natural river‐bed surfaces from which facsimiles are cast. Remarkably realistic casts with dimensions of 1 m by 2 m have been produced and their quality assessed using spatial data derived using automated digital photogrammetry. The casts reproduce the prototype surfaces with errors at millimetre scale (0·5 per cent of the microrelief). The technique has facilitated the introduction of sedimentary surfaces that incorporate natural, complex structures of grains up to cobble size into experimental channels where detailed studies of near‐bed hydraulics can be carried out. Copyright © 2003 John Wiley & Sons, Ltd.     

U-PVC贴砾滤水管井中二次成井技术

介绍了U-PVC塑料贴砾滤水管井中二次成井的几种方法;以大庆地区的试验为例,说明该技术的优越性。     

重庆上界高速公路E1合同段软基处理施工与评价

重庆上界高速公路E1合同段所经路线位于重丘区，冲坳沟多。且地表多为水田、鱼塘、藕池，常年积水，沟谷中多为低液限粘土。厚度3～10m不等。粘土多呈可塑状，部分为软塑状，含水量大，孔隙比高，压缩模量小，沉降量大、承载力小，属于软弱地基。高填方路基和部分涵洞位于软基上，设计采用碎石桩进行处理。本文就碎石桩施工工艺、施工控制指标以及施工后效果进行分析与评价。     

甘肃砂田西瓜覆膜补灌效应研究

为证明集雨补灌对砂田西瓜是否有效,在甘肃省皋兰县进行了集雨补灌效应研究,结果表明:在西瓜全生育期,各处理的土壤水分呈波动性下降,0～120cm土层含水量下降幅度在2.59%～4.13%之间,补灌量愈大,土壤含水量的下降幅度愈小。砂田西瓜全生育期耗水较少,不同补灌量处理的耗水量在175.9～218.9mm之间,比小麦等大田作物低100mm以上。灌水量对结瓜期的耗水量影响很大,灌水量增加,结瓜期耗水量增大。不同补灌量处理的西瓜产量差异达显著水平,随灌水量的增加,产量、单瓜重和采收瓜数相应增加。补灌量对西瓜的含糖量也有影响,补灌量低于45mm,各处理之间含糖量的差异不大,补灌量为67.5mm,西瓜含糖量降低4.4%以上。适量补灌可以提高西瓜水分利用效率,其中滴灌67.5mm处理水分利用率最高,达到267.2kg·hm-2·mm-1,比不补灌处理提高17.0%。但随灌水量的增加,灌水效率降低,单方水产值减少。由于补灌对西瓜的产量、含糖量和水分利用率都有影响,只有适时适量补灌,才能即提高产量和水分利用率,又不降低品质。研究结果证明,砂田集雨补灌栽培西瓜是集雨水利用的一种较经济高效的方式,但最佳补灌量应控制在45mm左右为宜。     

窑街三矿矿井水文地质特征及防治措施研究

根据生产实践总结，对窑街三矿矿井危害最大的是位于煤二层上部的第四系砾石层潜水，其次是烧变岩孔隙水与地表塌陷区积水，经多年水文地质资料分析，认为砾石层与地表水大通河水力联系密切，如采用帷幕注浆，打放水孔或泄水巷都不会取得好的效果，切断大通河与砾石层的水力联系，是根治砾石层最有效的方法，故要在充分研究大通河补给范围的情况下有目的地修筑拦河提与地下挡水墙，烧变岩孔隙水已利用打泄水巷，放水孔的方式排完，目前主要是严防地表水重新灌入，对塌陷区复垦，修筑防洪渠是防止大气降水进入塌陷区及防止地表水溃入矿井的有效途径。     

松辽盆地第三系含砾砂岩、砂砾岩层钻探硬质合金钻头的研究

设计试验了几种硬质合金钻头，得出发了在设计钻井含砾砂岩、砂砾岩层的硬质合金钻头时，应适当增加钻头口径，并应以球头硬质合金作为主要切削具的结论。     

碎石土压实性能试验研究

以现场取得的碎石土为原料,通过筛分试验确定其平均级配,以平均级配为基础,利用代替法设计试验级配。在试样含水量的确定上,结合碎石土的特点,以碎石土中细粒的多少来确定试样的含水量。通过等压制样的试验方法研究了含碎石(质量分数)、含水(质量分数)对碎石土压实性能的影响规律,并从理论上推导了最佳含石量的计算公式,通过理论与试验的对比分析,提出了确定碎石土最佳含水量和含石量的方法。     

A wind tunnel investigation of the influences of fetch length on the flux profile of a sand cloud blowing over a gravel surface

Wind tunnel tests were conducted to examine the fetch effect of a gravel surface on the ?ux pro?le of the sand cloud blowing over it using typical dune sand. The results suggest that the ?ux pro?le of blown sand over a gravel surface differs from that over a sandy surface and is characterized by a peak ?ux at a height above the surface while that over a sandy surface decreases exponentially with height. The ?ux pro?le of a sand cloud over a gravel surface can be expressed by a Gaussian peak function: q = a + b exp (?0·5((h ? c)/d)²), where q is the sand transport rate at height h, and a, b, c and d are regression coef?cients. The signi?cance of the coef?cients in the function could be de?ned in accordance with the fetch length of the gravel surface and wind velocity. Coef?cient c represents the peak ?ux height and increases with both wind velocity and fetch length, implying that the peak ?ux height is related to the bounce height of the particles in the blowing sand cloud. Coef?cient d shows a tendency to increase with both wind velocity and fetch length. The sum of a and b, representing the peak ?ux, increases with wind velocity but decreases with fetch length. The average saltation height derived from the cumulative percentage curve shows a tendency to increase with both the fetch length and wind velocity. For any fetch length of a gravel surface the sand transport equation is expressed as Q = C(1 ? U_t/U)(ρ/g)U³, where Q is the sand transport rate, U is the wind velocity, U_t is the threshold velocity measured at the same height as U, g is the gravitational acceleration, ρ is the air density, C is a proportionality coef?cient that decreases with the fetch length of the gravel surface. At a given wind velocity, the sand transport rate over a gravel surface is only 52–68 per cent of that over a sandy surface. The ?ux rate in true creep over a gravel surface increases with wind velocity but decreases with the fetch length, whereas the creep proportion (the ratio of creep ?ux to the sand transport rate) decreases with both the wind velocity and fetch length. Two‐variable (including fetch length and wind velocity) equations were developed to predict the peak ?ux height, average saltation height and transport rate. Copyright © 2004 John Wiley & Sons, Ltd.