沙漠矿物组成与生态修复的互馈关系研究

以乌兰布和沙漠和库布齐沙漠为研究区域,在流动沙丘、半固定沙丘和固定沙丘分别采集表层(0～20 cm)、中层(20～40 cm)和底层(40～60 cm)沙样,分析了沙漠不同深度沙样的粒径组成、矿物成分、风化程度及三者之间的关系。针对不同植被覆盖区域进行采样,研究了沙漠生态修复与风化程度、黏性矿物含量之间的关系,揭示了沙漠矿物风化程度与生态修复的互馈关系。结果表明:沙漠表层沙样粒径小于中层和底层沙样,黏性矿物含量高于中层和底层;风化程度越高,黏性矿物含量越高,粒径组成越细。植被盖度与矿物风化程度和黏性矿物含量之间具有良好的关系,植被盖度由4%增加至18%～22%时,黏性矿物含量和风化程度增加速率较快,之后增加速率减小。矿物风化程度随生态修复的时间逐渐增加,对库布齐沙漠来说,随着植被盖度和风化程度增加,黏性矿物中伊利石含量显著增加。     

干旱区高盐度潜水蒸发条件下土壤积盐规律分析

为分析干旱区高盐度潜水蒸发条件下土壤中盐分积累规律,利用室外土柱模拟试验开展了不同TDS(Total Dissolved Solids)(30和100 g/L)、不同包气带质地(细砂和粉质黏土)和不同潜水埋深(0.5、1.0和3.0 m)的高盐度潜水蒸发条件下分层土壤盐分的监测工作。通过对各个土柱不同深度7次取样得到的土壤平均含盐量数据分析表明:高盐度潜水蒸发条件下,潜水埋深越浅,土壤剖面上相同深度范围内的含盐量就越大;在其他条件一定时,包气带质地为粉质黏土的土壤剖面含盐量大于包气带质地为细砂的土壤剖面含盐量;由于黏性土的膜效应和土壤中积盐对土壤孔隙的填充作用,导致粉质黏土土柱上层的土壤含盐量表现为潜水TDS为30 g/L的大于潜水TDS为100 g/L的,在土柱下层的土壤含盐量表现为潜水TDS为30 g/L的小于潜水TDS为100 g/L的;由于TDS升高对毛细水的重力和土体结构的改变,随着潜水TDS的升高,粉质黏土土壤剖面上出现局部积盐深度下移的趋势。     

Deep soil water recharge response to precipitation in Mu Us Sandy Land of China

Soil water is the main form of water in desert areas, and its primary source is precipitation, which has a vital impact on the changes in soil moisture and plays an important role in deep soil water recharge (DSWR) in sandy areas. This study investigated the soil water response of mobile sand dunes to precipitation in a semi-arid sandy area of China. Precipitation and soil moisture sensors were used to simultaneously monitor the precipitation and the soil water content (SWC) dynamics of the upper 200-cm soil layer of mobile sand dunes located at the northeastern edge of the Mu Us Sandy Land of China in 2013. The data were used to analyze the characteristics of SWC, infiltration, and eventually DSWR. The results show that the accumulated precipitation (494 mm) from April 1 to November 1 of 2013 significantly influenced SWC at soil depths of 0–200 cm. When SWC in the upper 200-cm soil layer was relatively low (6.49%), the wetting front associated with 53.8 mm of accumulated precipitation could reach the 200-cm deep soil layer. When the SWC of the upper 200-cm soil layer was relatively high (10.22%), the wetting front associated with the 24.2 mm of accumulated precipitation could reach the upper 200-cm deep soil layer. Of the accumulated 494-mm precipitation in 2013, 103.2 mm of precipitation eventually became DSWR, accounting for 20.9% of the precipitation of that year. The annual soil moisture increase was 54.26 mm in 2013. Accurate calculation of DSWR will have important theoretical and practical significance for desert water resources assessment and ecological construction.     

双向“锅盖效应”诱发戈壁荒漠长草机制分析

我国西北荒漠戈壁滩是气候干旱的不毛之地。然而，塔拉滩光伏电站建成后，场区内却出现了大面积长草的现象。本文探讨了光伏电站中野草生长的可能水分来源。从定性的角度初步探究了双向“锅盖效应”的诱发机理。通过对比光伏板区与非光伏板区分析了浅层土壤3个测点、大气的温度和水分变化规律，以及对双向“锅盖效应”的年循环和日循环水分变化规律进行简单的定量分析。结果表明光伏发电板组件及地表硬化覆盖层综合因素诱发了双向“锅盖效应”；在夏季光伏板可显著降低土壤表层温度；冬、春季以正向“锅盖效应”为主，是维持浅层土壤野草存活的主要水分供给，年循环水分提升幅度约11%~20%；而夏、初秋季以反向“锅盖效应”为主，保证了野草每日水分需求变化在小范围内波动。本文的相关研究也可为荒漠治沙提供参考。     

沙漠风积沙溯源冲刷速度的影响因素初探

通过试验对沙漠风积沙的冲刷破坏形态以及影响沙漠风积沙溯源冲刷速度的主要因素进行初步分析。结果表明:在具有跌坎的地形上,沙漠风积沙在集中水流冲刷下,表面的冲刷剥蚀速度远小于跌坎处的溯源冲刷速度;沙漠风积沙的溯源冲刷速度与通过沙漠风积沙表面水流的单宽流量、跌坎处初始落差以及沙漠风积沙的含水率等因素有关;在初始落差一定的情况下,溯源冲刷速度随单宽流量的增大而加快;在相同单宽流量作用下,溯源冲刷速度随初始落差的增大而增大。     

港珠澳大桥隧道人工岛暗埋段基坑防渗方案研究

拟建的港珠澳大桥,为实现桥隧平顺过渡,设置了东、西两座海中隧道人工岛.人工岛地基土上部为深厚淤泥及粉质黏土夹砂层,下部为承压水中砂层,基坑最大开挖深度达15.5 m.为达到基坑干地安全施工目的,综合考虑人工岛支护结构、地基处理方案等因素,对西人工岛暗埋段基坑防渗降水的保留粉质黏土防渗层方案和设置升浆混凝土封底方案进行了...     

沙漠砂取代率及黏土掺量对砂浆性能影响研究

在沙漠内修建筑工程,所用砂料需要外运且费用较高,为此,开展了试验研究。选用金沙滩沙漠砂部分地取代中砂来配置砂浆进行施工。通过试验,研究了沙漠砂取代率和黏土掺量对砂浆抗压强度、稠度的影响。结果表明,随着沙漠砂取代率的增大,砂浆抗压强度呈先升高后下降的趋势,当取代率为20%时达到峰值;而当沙漠砂、黏土取代率继续增大时,砂浆稠度分别呈下降和上升趋势。研究成果对于科学利用沙漠砂、指导掺和料对砂浆的改性,具有一定的指导意义。     

太行山山地丘陵区雨季土壤水分动态规律研究——以崇陵流域为研究区

以河北易县崇陵丘陵山区为研究对象,在实验的基础上,针对主要土壤质地、坡度和植被,研究不同下垫面条件下土壤水分变化规律,得到典型土壤质地的物理参数,并对土壤水分的动态变化规律进行了研究。实验结果表明,土壤质地对土壤物理参数和土壤水分变化影响非常大,明显强于植被和坡度。土壤质地对表层和深层水分的变化影响很大,活跃层受质地影响相对较小。     

A Dissipative Hydrological Model for the Hotan Oasis (DHMHO)

Various hydrological models have been designed to simulate moisture transformation in the water-cycle system between atmospheric water, surface water, soil water and groundwater. But few have been designed specially for oases in arid desert areas where the ecology and the environment are vulnerable because of unwise water-land resources utilization. In order to analyze the moisture transformation in the Hotan Oasis in the Taklimakan Desert in China, and hence to provide scientific references for the rational exploitation and allocation of the limited water-land resources, for the purpose of ensuring that the vulnerable ecology and environment there can be gradually improved and the social economy there can develop sustainably, a dissipative hydrological model for the Hotan Oasis (DHMHO) was developed. It was an outcome of years of systematic study on the moisture transformation in arid areas and on the water–land conditions in the Hotan Oasis. Based on statistics, DHMHO introduces two empirical equations whereby we dynamically calibrated model parameters with monthly data from year 1971 to 1995. Then the calibrated parameters were used to model the moisture movement from 1996 to 2003 and thereafter rationality check and error analysis were conducted. The error analysis results show that the absolute relative errors between simulated and observed groundwater depth values are almost (11 of 12 points) within 20%, and those in annual watershed outflow simulation are mostly (six of eight points) within 20% with an average annual Nash–Sutcliffe Efficiency Coefficient (NSEC) of 0.80. With DHMHO and IPCC assessment, we also simulated the moisture transformation and dissipation in the Hotan Oasis from the year 2011 to 2020. Results show details of the water resources in the Hotan Oasis in the next decade and hence are expected to provide scientific references for establishing rational exploitation and allocation policies on the local water–land resources in the future.     

风积沙路基压实特性试验研究

风积沙是沙漠地区路基的主要填料,其压实质量直接影响着公路的强度与稳定性。通过重型击实试验和振动试验并结合理论分析,研究了含水率、颗粒级配、振幅、振动频率、振动时间等因素对风积沙压实的影响规律,用以指导路基施工。同时试验方法不同,测得的最大干密度值存在差异,为了能用压实度合理评价路基压实质量,对试验适用范围进行了界定。     

准噶尔盆地南缘初春沙漠含水率、沙漠冻土及植被覆盖率研究

准噶尔盆地南缘处于沙漠绿洲交汇处,生态环境脆弱,当地植被是“三北”防护林的重要组成部分,冬季降雪融化形成的水源,是当地沙漠植被赖以生存的主要组成部分之一。本文根据在当地沙丘多点取土,测得沙丘阳坡、背阴坡和沙谷的冬季冻土深度分别13cm、29cm、32cm;利用烘干法测土壤质量含水率．计算出沙丘阳坡、背阴坡和沙谷的累积含水量分别为1．3mm,2．1mm,1．67mm;同时测量三点的植被覆盖率变化,得出当地沙漠不同地形的含水率变化和植被覆盖率的关系,为当地生态建设提供数据支持。     

长期膜下滴灌棉田土壤水盐空间分布特征研究

为分析播种前膜下滴灌棉田土壤不同深度水分和盐分的分布特征,对1998年开始利用膜下滴灌种植技术的棉田进行大规模网格取土,主要分析了棉田土壤水盐空间分布特征。研究结果表明:在生育期初播种前,棉田土壤0~5、5~20、20~40、40~60、60~80及80~100 cm对应土层中,水分变异系数小于盐分变异系数,且都属于中等变异性;土壤各层水分和盐分含量总体都呈现出表层土壤水分和盐分含量较低,深层土壤水分和盐分含量较高的分布规律;在0~100 cm土层中,随着深度增加,水分和盐分含量呈现出先增大后减小的趋势;设置排盐沟,能够使土壤盐分向排盐沟运移,有助于棉田改良。     

含砂量对黄原胶复合黏性土抗裂和抗冲刷性能的影响

为增强黏性土的抗裂和抗冲刷性能,对掺加不同含量砂土的黄原胶复合黏性土开展了一系列室内蒸发、干缩开裂和抗冲刷试验,通过测算试样含水率和土体抗冲刷系数,结合图形分析软件定量分析了土体表层裂隙的发育情况,以研究复合黏性土体内部水分变化规律及其抗裂和抗冲刷性能。结果表明：随着黏性土中砂土颗粒的掺入,试样的裂隙率、裂隙宽度和受冲刷破坏程度呈现先增大后减小的趋势;当含砂量为30%时,素土及黄原胶复合试样的裂隙率、裂隙宽度和受冲刷破坏程度均为各含砂量下的最大值;当含砂量为50%左右时,对于黄原胶复合黏性土,黄原胶胶体与砂土颗粒形成具有一定强度的稳定结构,其抗冲刷性能得到显著提高。     

铁谢——神堤河段地层土体特性及滩岸稳定分析

在铁谢—神堤河段选择典型部位开展了土体物理力学特性试验,同时探讨了不同含水率状态下土体力学特性的变化规律,并对滩岸稳定性进行了初步分析。结论认为:①粉质黏土、粉质壤土、砂壤土、细砂、中砂、粗砂的摩擦角、干密度均呈依次增大的趋势,压缩系数、液限含水率、孔隙比、天然含水率均呈依次减小的趋势;②土体含水率发生变化时,土体的状态随之而变;③滩岸边界特性、土层结构、水流条件和河床冲淤演变特性等在滩岸崩塌过程中起到了重要的作用,而且这些影响因素在不同时期所发挥的作用也不同。     

秋浇定额对土壤盐分变化的影响分析

秋浇是内蒙古引黄灌区传统的秋后淋盐、春季保墒的一种特殊的灌水制度.本文通过分析不同秋浇定额灌溉条件下土壤盐分的变化,研究了土壤盐分变化与秋浇定额的关系.结果表明:20 cm以上土层的土壤含盐量变化与秋浇定额存在较好的相关关系,秋浇前后、秋浇前～春播前秋浇定额在1 725 m~3/hm~2时土壤含盐量减少最多,秋浇定额小于1 725 m~3/hm~2时,土壤含盐量的减少量随秋浇定额的增大而增大,秋浇定额大于1 725 m~3/hm~2时,土壤含盐量的减少量随秋浇定额的增大而减少;20 cm以下土层含盐量变化则不完全受秋浇定额的影响.     

颗粒级配与压实度对路基土-水特征曲线的影响

为探究东北寒区公路路基黏土的基质吸力与其含水率、压实度、颗粒级配之间的关系,通过控制黏土中细粒含量,制备3种不同颗粒级配的黏土试样,采取人工压实的方法制备3种不同压实度的土样,采用离心机法测定不同颗粒级配、不同压实度条件下的重塑黏土的基质吸力.结果表明,在同一种压实度情况下,体积含水率相同时,细粒含量越多,黏土的基质吸...     

含水率对高液限细粒土砾与粉质黏土抗剪强度影响比较研究

近年来,随着极端气候的变化,土石坝安全性问题日益突显。为了研究不同筑坝材料对土石坝安全的影响,利用应变直剪仪对粉质黏土和高液限细粒土砾土样在不同含水率和实施不同正应力下进行不排水不固结快剪试验,研究不同含水量和不同应力情况对土的抗剪强度的影响。试验结果表明,粉质黏土在最大干密度和最优含水率时抗剪强度最大,在最优含水率以前随含水率越大抗剪强度越大,在最优含水率以后随含水率越大抗剪强度越小;而高液限细粒土砾的含水量越大抗剪强度越小。     

黄河内蒙古段乌兰布和沙漠入黄风积沙监测研究

黄河内蒙古段途经乌兰布和沙漠,局部河段发展为＂地上悬河＂,洪灾、凌灾频繁发生。对乌兰布和沙漠沿黄河段风沙入黄的初步监测结果进行了分析与探讨,揭示沿黄段入黄风沙运移规律并精确计算出风积沙入黄沙量。国家及有关部门应对乌兰布和沙漠对黄河的危害高度重视,形成多渠道、多学科联合攻关研究的平台,使研究结果更好地为科学治理黄河泥沙问题及完善黄河沿岸综合防护体系提供科学依据。     

Comparison studies of unsaturated flow below annual and perennial plants

Values of unsaturated water content determined with neutron moisture measurements (NMM) reveal different water profiles below different plantings. In the extremes, calibration requires a linear and logarithmic response (using the Lambert-W function) along with the normal submersion in a drum of water. Nevertheless a post-calibration with a hydraulic push sampler was used for confirmation. Data were collected at six pastures near the Western Australia coast near Geraldton, with four replicates through the profile. The sites have mostly sandy soils and receive 300-500 mm of rainfall annually. Findings generally showed that, if there was sufficient water, as in 2006, the perennials were able to use the water evenly throughout the vertical profile. Otherwise, with low rainfall, as in 2009, perennials struggle to survive and use less water than the annuals. Modelling of the soil water movement, plant growth and calibration/recalibration is and will be used to get a maximum likehood fit. Clearly, in desert conditions and little or no vegetation, rainfall tends to build up deep in the profile, increase salinity in groundwater, and create waterlogging. Any vegetation is helpful; perennials more so; provided they have sufficient water and are not significantly harvested.     

半干旱草地土壤粒径分形维数及空间变异特征

本文以毛乌素沙区内半干旱草地土壤颗粒为研究对象,运用地质统计学方法分析土壤颗粒大小含量及其分形维数的空间变异性,认为分形维数与沙粒含量线性负相关,与粘黏粒含量线性正相关。土壤黏粉粒损失导致土壤沙化加剧,分形维数减少,说明分形维数可以反映土壤颗粒物质的损失状况及土壤沙质荒漠化的程度。在20m采样尺度上,各空间变量由随机因素引起的变异占总变异的比例较小,自相关引起的变异比例较大。以分形维数的空间变异性表示土壤质地的分布,不但方法简单且更经济实用。