通过田间试验,研究了不同灌溉水平(95％θf(土壤田间持水量)、80％θf和65％θf,依次记为FI、DI1和DI2)和施氮量(0、70、140 kg·hm-2和210 kg·hm-2,依次记为N0、N70、N140和N210)对春玉米的产量、水氮利用效率和经济效益等的影响.结果表明:灌水和施氮均可使春玉米产量增加,在FI和DI2灌溉条件下,春玉米产量随施氮量的增加而显著增加,N210处理的籽粒产量比N0处理分别高21.8％和18.8％;但在DI1灌溉条件下,N140和N210处理下的春玉米产量间无显著差异,DI1灌溉水平比FI和DI2平均增产5.5％和8.3％.增施氮肥可提高春玉米水分利用效率,但施氮量超过70 kg·hm-2水分利用效率显著降低;相同灌溉水平下,氮肥偏生产力随施氮量的增加而显著降低,N70、N140和N210处理的氮肥偏生产力均值分别为262.59、141.52 kg·kg-1和97.31 kg·kg-1.综合考虑产量、经济效益和环境因素,在中国河西地区推荐春玉米的最适宜水氮组合为DI1×N140,其产量达23.68 t·hm-2,净效益达25390元·hm-2.

为探索河西地区春小麦节水高产的微喷带灌水定额,以"永良4号"为试验材料,在生育后期(孕穗期―成熟期)设置5次灌水,4个灌水定额30 mm(W30)、40 mm(W40)、50 mm(W50)及60 mm(W60),研究了河西春小麦生育后期在微喷带灌溉下不同灌水量对其生长、产量和水分利用效率的影响.结果表明:随后期灌水量的增加,春小麦株高呈增加趋势,W50和W60处理分别比W30处理高7.3％、9.27％;灌水有利于光合同化物向籽粒的转移,W50和W60处理千粒重分别比W30处理显著提高12.6％、15.29％;各处理春小麦的穗粒数、产量和水分利用效率随着灌水量的增加均呈先增加后减小的变化趋势,且均在W50处理达到最大,分别比W30显著高11.74％、35.95％和18.24％.从节水高产的角度综合考虑灌水量、产量和水分利用效率,W50处理可作为河西春小麦生育后期较适宜的灌水处理.

Soil cement is a synthetic building materials,the compacted cement soil has good mechanical properties of engineering. Damage calcula-tion model of the clay cement-soil seepage deformation was established,in order to explore the clayey soil cement penetration deformation law. The paper carried on the indoor seepage deformation experiment research of two factors on the affect clay soil-cement seepage deformation damage more prominent cement and ages by the method of indoor test. The results of statistics and regression analysis show that there is a correlation of the linear logarithmic height between the slope of the clay cement-soil seepage deformation damage and the dosage of cement and ages. Preliminary test model between them is established.

In order to understand the cement soil compaction characteristic, through indoor compaction test methods, study on the different amount of cement soil in dry and wet compaction test. The results showed that in the standard compaction power, the optimum moisture content and the maximum dry density of cement soil present a certain regularity with different cement quantity. When the cement quantity and compaction work at the same time, the optimum moisture content and the maximum dry density are significant differences in the dry and wet compaction conditions. It is of practical significance to the geotechnical engineering construction of using cement soil construction or reinforcement.

To explore the cement soil's permeability coefficient variation,we performed laboratory permeability test on cement soil of different dry densities,cement contents and ages.The test results show that cement soil's permeability coefficient is closely related with its dry density,cement content and age: when the dry density and age remain unchanged,the permeability coefficient increases with the increase of cement content;while when the dry density under standard compaction work and the age remain the same,the permeability coefficient decreases with the increase of cement content;when the dry density under standard compaction work and the cement content remain the same,the permeability coefficient decreases with the increase of age.These conclusions are helpful to explore cement soil's permeability,and are also practical for the construction and reinforcement of geotechnical engineering using cement soil.

现代建筑物的高大发展趋势对地基土体的力学性能提出了更高要求.利用水泥对土的抗压、抗剪、抗拉等力学性能改善突出的特点,水泥土在地基加固、边坡处理、渠道防渗、抗渗等方面将有着广泛应用前景.为了探索水泥土抗拉强度随水泥掺量、龄期的变化规律,采用特制单轴拉伸仪,对不同水泥掺量和龄期的水泥土进行了室内单轴直接拉伸试验研究.结果表明:水泥土单轴抗拉强度较素土显著增强,随水泥掺量和龄期的不同,呈现出有一定规律的变化.

实践教学是大学学习的重要环节,是理论和实践相结合的重要手段.传统的大学生集中实践教学模式具有省时、省力、学习阶段明显等特点,但实习效果不佳,重形式轻质量是其突出弊端.加强教学质量、增强学生实践能力和创新能力的培养,探索更有效的实习教学模式,是大学实践教学值得探讨的重要课题.本文就我校实行的本科生实践教学导师制模式的改革探索进行分析,将改革成效成文供有关人才培养单位参考借鉴.

Cement-soil is a kind of hydraulic composite building materials which is made by a certain percentage of cement soil particles and water. In order to make a deep research of seepage deformation and the variation law of cement-soil, laboratory test methods were adopted, carrying on deformation tests of indoor penetration on dry density, cement content and age etc, the factors owning outstanding effect on the seepage deformation and failure of cement-soil. The results shows that the seepage deformation and failure appear to change in certain laws with dry density, cement content and age. The gradient of seepage deformation and failure can reach one thousand under the condition that cement percentage is 5%, compaction maximum dry density is standard, and the age is 7 days. And numerical value will be enhanced significantly with the increase of cement content, dry density and the prolong of age. The seepage deformation and failure of cement-soil is not ordinary piping effect or soil-flow failure, but the form of shearing failure. The conclusion has not only a positive exploration significance of the academic research of the seepage deformation and failure of cement-soil, but also a certain practical significance on the geotechnical construction applying cement soil as impermeability.

Because cement soil has a lot of prominent engineering advantages,as resist compression,shear,high tensile strength and impervious,and so on,it has a wide application prospects in foundation reinforcement,slope treatment,canal seepage control and impervious.In order to have a better understanding of the soil cement compression path and intensity variation with the cement content and age variation,a modified triaxial compression apparatus is used to take uniaxial compression tests on different cement content and age of cement soil.The results show that the lower dosage cement and the shorter age of cement soil,the compressive stress-strain curve is relatively flat,it has a small stress,large strain plasticity failure characteristics;the higher dosage cement and the longer age of cement soil,the compressive stress-strain curve is steeper,it has a large stress,small strain brittle failure characteristics.The compressive strength increases with increasing cement content and age,the increase rate gradually decreases,on the contrary,failure strain of cement soil decreases with increasing cement content and age,and the decrease amplitude gradually slow.

Currently,in China,compaction test with five-point method is the most basic earthwork test in the various specifications of soil test.The test has some drawbacks such as needing much more test soil and test time,great effort and meeting trouble in data processing.In order to overcome these shortcomings,different soil samples being prepared is dehydrated under the conditions of the timing constant pressure that its moisture content is higher than its plastic limit water content.There is a law that the moisture content after being dehydrated was stable,it is always lower than the optimum water content under standard compaction work.Based on the characteristic,optimum moisture content of the soil could be calculated by dehydrated moisture content and the correlation coefficient multiplied.Soil optimum moisture content and maximum dry density under standard compaction work could be obtained quickly and accurately using single-compaction method.After improving the method of compaction test,it is simple,fast and reliable comparing with the five-point method.

采用野外抽水试验方法,进行了潜水和承压水完整井稳定流流量-降深试验研究.结果表明:两类地下水完整井稳定流出水量因地下水埋藏条件、抽水条件不同而主导作用因素不同,在抽水降深相同时,渗透系数的大小对井的流量起决定性控制作用.

The compaction test of cohesive soil is one of the most basic soil mechanics experiments in various types of geotechnical engineering test specifications,the aim of which is to obtain the optimal water content and maximum dry density under a certain compactive effort.The test results could not only be directly used to guide the engineering constructions,but some other mechanical indexes are also obtained with the compaction test results,therefore,it is particularly important to achieve the accurate compaction test results.Here,by using the soil saturation analysis method,the reasonable calculation and analysis are made for a compacted soil whose saturation coefficient is greater than 100%.The results show that the root cause of problems is not to consider the restrictive effect of the water in clayey soil upon the soil dry density.And it is proposed that the percent moisture content has certain limits on the clay dry density,that is,the maximum dry density of clay soil would not exceed the maximum dry density in saturated state of the compacted soil.

Research is done on environmental factors of the summer corn and physiological indicators under the conditions of film mulch and open field through comparative experiments.Mulching can change in the soil water cycle,and increase shallow soil temperature,and promote soil moisture migration,and inhibit evaporation from plants,and can surface soil in the Absence of long-term precipitation circumstances and maintain a relatively high water content.Mulching has improved the growth environment of the summer corn;there is a marked increase in the summer corn leaf area per plant in the whole growth period.

采用膜缝沟灌和露地沟灌对夏玉米的生长发育进行了对比试验,结果表明:膜缝沟灌在一定程度上调节了耕层的土壤环境,抑制了棵间蒸发,提高了土壤温度,促进了夏玉米根系的生长发育;膜缝沟灌玉米叶面积指数增大,后期表现出较好的保绿性,叶面积指数维持在3.0以上;整个生育期内覆膜夏玉米干物质积累量比露地积累量大,从抽雄吐丝至乳熟期覆膜穗粒的增长速度明显高于露地.

Compared with the open field test,we studied the effect of film slit furrow irrigation on soil moisture content,soil temperature and status of summer maize during growing period.The result showed that the soil moisture content is higher than the open field when covered by plastic film,and,on average,it is 5.5% higher in 0～40 cm layer,2.9% higher in 40～80 cm layer and 1.3% higher in 80～120 cm layer.In addition,after film covering the soil temperature in tillage layer is higher than that in the open field,and the varying range of soil temperature with film covering at 8∶00,14∶00 and 20∶00 was 1.13℃,0.57℃ and 0.34℃,respectively,comared to 2.06℃,1.38℃ and 1.01℃ in open field.Under the same irrigation conditions,the plant height and dry matter of summer maize is 49 cm and 126 g/plant respectively higher than that in the open field.So film covering is conducive to the growth of summer maize.

Research is carried out for the maximum dry density of each residue earth material,through result analysis,it is found that there exists the linear relation between the maximum dry density and quantity of the sorting and the surplus. Thus,the idea of the maximum dry density that can be obtained indirectly from the extension of coarse-grained earth series,is proposed.

In view of the difficulty of determining the density of soil mixtures with giant grains in engineering practice,an experimental method is proposed.This method is trying to establish the relationships between contents of giant grains and maximum as well as minimum dry density of soil mixtures in laboratory.In the process of experiment the giant grains are to be winked out step by step and the relative density of the residual soil is measured accordingly.It is found that the relationship is positive linear correlated.According to this experimental relationship the relative density of soil mixtures with giant grains in prototype can be obtained by the method of extrapolation.

Through studying on the control experiment of the coarse-grained soil permeation damage slope of different grain composition,the paper points out that there is relativity between the scope of permeation damage and its grain composition of course-grained soil.And it comes to a conclusion that the permeation damage slope of the coarse-grained soil of well graded with a definite proportion of fine granule is higher than that of poorly graded.The study will lay a good foundation for the research on the relation between the permeation stability and the grain composition of coarse-grained soil.At the same time,the paper points out the direction of the research field,and provides some beneficial exploration for the engineering characteristics of the permeation stability of coarse-grained soil.

AbstrcatThe film bore irrigation technique is a new irrigation technique.Based on the ground film and cultivation technique,the technique uses the ground film to transfer water by preventing water evaporation from ground soil.This paper describes the present research status,characters,water saving mechanism,problems and solutions in practice of the film bore irrigation technique and provides theoretical and practical references in the field.

无粘性粗粒土颗粒组成具有较大分散性特点,其渗透系数受颗粒组成影响较大.为了探寻无粘性粗粒土级配对渗透系数的影响,通过室内试验方法进行不同级配的无粘性粗粒土渗透试验研究,试验结果表明,无粘性粗粒土渗透系数与其颗粒级配具有相关性.以太沙基公式为例,将原有公式修正为与级配参数相关的函数表达式,从而体现出无粘性粗粒土渗透系数与级配的关系,为无粘性粗粒土的工程特性进行了有益的探索.