Assessment of rapid impact compaction in ground improvement from in-situ testing

Ground improvement has been used on many construction sites to densify granular materials, in other word, to improve soil properties and reduce potential settlement. This work presents a case study of ground improvement using rapid impact compaction （RIC）. The research site comprises the construction of workshop and depots as part of railway development project at Batu Gajah-Ipoh, Malaysia. In-situ testing results show that the subsurface soil comprises mainly of sand and silty sand through the investigated depth extended to 10 m. Groundwater is approximately 0.5 m below the ground surface. Evaluation of improvement was based on the results of pre- and post-improvement cone penetration test （CPT）. Interpretation software has been used to infer soil properties. Load test was conducted to estimate soil settlement. It is found that the technique succeeds in improving soil properties namely the relative density increases from 45% to 70%, the friction angle of soil is increased by an average of 3°, and the soil settlement is reduced by 50%： The technique succeeds in improving soil properties to approximately 5.0 m in depth depending on soil uniformity with depth.

Effects of Soil Testing and Formulated Fertilization on Yield and Economic Benefit of Major Crops in Burundi

[Objectives]The purpose of this study was to provide technical support for high-yield cultivation of major crops in Burundi,thereby increasing local farmers'income and promoting sustainable development of agriculture in Burundi.[Methods]In the IMBO and MOSO test stations of the Burundi Academy of Agricultural Sciences and the Burundi Fruit and Vegetable Extension and Service Center,soil testing and formulated fertilization test and demonstration was carried out in rice,maize and cabbage.The test set up three treatments,soil testing and formulated fertilization(STFF),local routine fertilization(RF)and non-fertilization(CK)to investigate the effects of soil testing and formulated fertilization on the yield and economic benefit of the crops.[Results]In the plot test,the yield and net economic benefit of rice,maize and cabbage were both highest in the STFF treatment.Compared with those in the RF treatment,the yield of rice,maize and cabbage increased by 19.0%,25.7%and 33.0%,respectively,and the net economic benefit increased by 4292,2837 and 8232 yuan/ha,respectively.In the field test,the yield and net economic benefit of rice,maize and cabbage were also both highest in the STFF treatment.The yield increased by 18.1%,24.3%and 25.9%,respectively,and the net economic benefit increased by 4142,2881 and 8665 yuan/ha,respectively compared with those in the RF treatment.[Conclusions]Soil testing and formulated fertilization not only increased rice,maize and cabbage yield per unit area,but also increased farmers'income in Burundi.It is one of the important technical measures to promote the increase of agricultural production and income in Burundi.

Research on wind erosion processes and controlling factors based on wind tunnel test and 3D laser scanning technology

The study of wind erosion processes is of great importance to the prevention and control of soil wind erosion.In this study,three structurally intact soil samples were collected from the steppe of Inner Mongolia Autonomous Region,China and placed in a wind tunnel where they were subjected to six different wind speeds(10,15,17,20,25,and 30 m/s)to simulate wind erosion in the wind tunnel.After each test,the soil surfaces were scanned by a 3D laser scanner to create a high-resolution Digital Elevation Model(DEM),and the changes in wind erosion mass and microtopography were quantified.Based on this,we performed further analysis of wind erosion-controlling factors.The study results showed that the average measurement error between the 3D laser scanning method and weighing method was 6.23%for the three undisturbed soil samples.With increasing wind speed,the microtopography on the undisturbed soil surface first became smooth,and then fine stripes and pits gradually developed.In the initial stage of wind erosion processes,the ability of the soil to resist wind erosion was mainly affected by the soil hardness.In the late stage of wind erosion processes,the degree of soil erosion was mainly affected by soil organic matter and CaCO_(3)content.The results of this study are expected to provide a theoretical basis for soil wind erosion control and promote the application of 3D laser scanners in wind erosion monitoring.

Effectiveness of Fiber Bragg Grating monitoring in the centrifugal model test of soil slope under rainfall conditions

Centrifugal model testsare playing an increasingly importantrolein investigating slope characteristics under rainfall conditions. However, conventional electronic transducers usually fail during centrifugal model tests because of the impacts of limitedtest space, high centrifugal force, and presence of water, with the result that limited valid data is obtained. In this study, Fiber Bragg Grating(FBG) sensing technology is employed in the design and development of displacement gauge, an anchor force gauge and an anti-slide pile moment gauge for use on centrifugal model slopes with and without a retaining structure. The two model slopes were installed and monitored at a centrifugal acceleration of 100 g. The test results show that the sensors developed succeed in capturing the deformation and retaining structure mechanical response of the model slopes during and after rainfall. The deformation curvefor the slope without retaining structure shows a steepresponse that turns gradualfor the slope with retaining structure. Importantly, for the slope with the retaining structure, results suggest that more attention be paid to increase of anchor force and antislide pile moment during rainfall. This study verifies the effectiveness of FBG sensing technology in centrifuge research and presents a new and innovative method for slope model testing under rainfall conditions.

Application Strategy of CBR Test in Highway Engineering

California Bearing Ratio(CBR)test is highly professional and requires a high level of skills.In order to improve the accuracy of the test results,the relevant staff will not only need to understand the rules and procedures involved in the test,they would also need to be meticulous in their work to avoid human errors,provide good data support for highway engineering,and improve the overall quality of the project.Therefore,this paper presents an analysis of the application of CBR test in highway engineering,which can provide reference for engineering and promote the development of the highway industry.

适用于植物生长的透明土制备及其性能试验

植物根系可以增强土体的抗剪强度,预防浅层滑坡。以熔融石英砂、正十二烷为主要成分的透明土技术为可视化观察植物根系提供技术支撑,但是植被难以在其中生长,无法克服根土耦合和观测的难题。该研究改进透明土配制工艺,提出既能模拟土壤力学性能又能适应植被生长的透明土方案。以侧柏根系为例,通过直剪试验分析含液率和含根率对根土复合体抗剪强度的影响,并以透明素土为对照。进一步采用粒子图像测速(particle image velocimetry,PIV)技术分析透明素土及根土复合体边坡模型在坡顶加载工况下的宏细观力学特征。研究表明:1)改进透明土能适应植被生长并观测根系形态,并能模拟根土复合体的力学性能,当含液率≥20%时,具有良好透明度,能观测植物根系形态。2)随着含液率的增加,透明土黏聚力下降,当含液率从0升至25.8%时,透明土的黏聚力下降了64.09%。当含根率从0增至0.6%时,黏聚力增加了127.50%。根系的加入,增加了透明土的黏聚力,但随含根率的增大,对黏聚力增益效果逐步减弱。3)根系的存在极大减小了边坡在坡顶荷载作用下的微观形变,有效预防潜在滑坡的发生。研究成果可为根系固土研究提供材料制备工艺和思路。

含粗粒滑带土剪切带演化及空间展布规律研究

对含不同强度粗颗粒的滑带土进行了可视化中型直剪试验,通过竖直置入铝丝观察剪切后铝丝变形情况获取剪切破坏带的空间信息,并建立了剪切带空间曲面方程。通过粒子图像测速(particle image velocimetry,PIV)技术对可视面处二维剪切带信息进行提取,并与剪切试验得到的空间曲面方程的边界外推值进行对比,证明了空间曲面方程与PIV技术能够描述剪切带特征。然后通过PIV技术对不同剪切总位移与某一剪切位移下短时间内相对位移规律进行了分析。最后分析了预制损伤与粗颗粒强度对剪切带特征的影响。研究结果表明,剪切带形状为两端薄中间厚的带状,可采用高斯曲面方程对剪切带轮廓进行拟合。剪切带在发展过程中经历压密、自由损伤、损伤沿固定路径发展与剪切带贯通4个阶段,损伤使得剪切带发展各阶段前移,粗颗粒强度会对局部剪切带变形产生较大影响而对整体剪切带的变形影响较小。该研究成果对于揭示滑坡剪切带形成与演变规律从而设计合理的边坡防治方案具有重要意义。

透明土试验技术在滑坡降雨入渗中的研究与应用

由于滑坡体内部结构的复杂性和不可视性,使得滑坡降雨入渗及其渗流过程无法直观观测,从而难于查明滑坡灾变演化全阶段中降雨入渗的具体作用过程,导致降雨诱发滑坡成灾机制的认识存在不确定性,因此,发展可以观测滑坡内部降雨入渗灾变过程的新技术手段,对深入理解降雨诱发滑坡灾变机理具有重要意义。而透明土试验技术则使岩土体内部非介入式、连续、无损、可视化测量得以实现。从透明土材料特性、岩土工程性质、试验设备与图像处理解析技术等方面,总结透明土试验技术发展现状及其在不同领域的应用,重点概述该技术在边坡工程领域的应用和渗流过程可视化模拟中的实践,并讨论将其应用于滑坡渗流直观观测的可行性。在此基础上,针对透明土材料进行筛选和对制备方法进行优化,利用透明土替代传统土工模型材料建立适用于渗流过程观测的滑坡透明土物理模型,开展降雨条件下滑坡渗流物理模拟试验,获取降雨入渗诱发滑坡灾变全过程信息,确定滑坡体内部地下水渗流过程及其变化特征。该模型试验是透明土试验技术在滑坡渗流可视化观测领域一次有效的应用实践,拓展了滑坡灾害可视化模拟新途径,进一步确定地下水渗流对滑坡的复杂影响,有利于揭示降雨诱发滑坡演化规律、深入探索滑坡滑动机制,为降雨滑坡灾害防治和灾害规划提供科技支撑。

固定化微生物技术在小秦岭金矿区农田土壤修复中的应用

为积极探索土壤污染防治新路径,开展固定化微生物技术在土壤原位生态修复方面的应用研究。选取豫西小秦岭金矿矿区及周边农田土壤进行重金属含量测定及分析评价,发现该地区土壤中Pb^(2+)元素污染风险较大。将侧孢芽孢杆菌、放线菌及酵母菌株进行固定化混合菌制备并开展土壤原位生物修复。发现经固定化混合菌处理后土壤脲酶活性显著高于CK。以Pb^(2+)钝化效率及去除率提高为目的,分别采用单因素试验及响应面法对影响土壤修复效果各因素进行分析,最终确定Pb^(2+)最佳去除条件为固定化混合菌投加量10.496%,处理温度30.784℃,pH值6.242,Pb^(2+)去除率理论值为72.754%。对此模型进行试验验证,结果与理论值接近,说明响应面分析可起到优化土壤原位修复试验参数的目的。

EPC项目中地源热泵系统的设计优化与施工技术

浅层地热能是一种重要的新型能源,开发浅层地热能主要作用是为建筑物提供供暖制冷,目前利用浅层地热能作为冷、热源的地埋管地源热泵系统在工程中得到广泛应用。对芜湖某EPC公建项目地源热泵系统进行了研究,介绍了项目场地区域岩土热响应试验情况,根据相关规范要求进行了地埋管地源热泵系统的设计优化,阐述了地埋管地源热泵的施工技术。由岩土热响应试验得出芜湖地区适合做地源热泵系统,利用规范中热量平衡原理,优化了初步设计中地源热泵的数量和节点处理措施,缩短了施工工期并节省了工程造价,针对地源热泵施工过程中的技术难点提出应对措施,对工程实际具有参考意义。

岩土工程勘察原位测试技术研究

文章全面回顾岩土工程勘察测试技术的现状和发展趋势,梳理了土体原位测试技术和岩体原位测试技术的分类、优缺点及未来发展趋势,结果表明:测试技术朝自动化、数字化和智能化方向发展是未来趋势,人工智能和物联网技术在即时数据分析和远程监控中具有突出的应用潜力。

岩土工程勘察中土工试验质量管理的研究

本文主要简单介绍了岩土工程勘察和土工试验的相关内容,阐述了岩土工程勘察中开展土工试验活动的必要性,讨论了岩土工程勘察中土工试验技术的应用,明确岩土工程勘察中土工试验工作的重要性,转变传统的岩土工程勘察模式,充分发挥土工试验技术作用,保障土工试验质量,为岩土工程勘察工作奠定了扎实基础,保障岩土工程的顺利开展,提高岩土工程施工安全,实现岩土工程施工效益最大化。

测土配方施肥技术在哈尔滨市发展历程及现状

为进一步推广测土配方施肥技术,实现农业的绿色可持续发展,通过查阅历史资料、工作方案和试验数据等,将测土配方施肥技术在哈尔滨市的发展历程归纳为探索尝试、奠定基础,建设体系、初具雏形,全面启动、迅速发展,大力推广、整建推进,重心调整、绿色发展,科学施肥、推广“三新”六个阶段。从开创科学施肥工作新局面、促进粮食高产稳产、保护农业生态环境和提高农民科学施肥意识等方面总结哈尔滨市测土配方施肥技术取得的成果。2014-2023年累计开展农户调查92727户,采集化验土壤样品132319个,基本摸清了哈尔滨市耕地土壤理化性状,编制了地力评价类书籍7本,县域耕地土壤养分状况专题报告11本,制作发放施肥建议卡132580份,发布施肥配方14514个,使哈尔滨市施肥配比更加合理,在减少施肥量的同时保证了粮食产量。目前哈尔滨市测土配方施肥技术发展仍存在基层化验室难以完成化验任务、推荐施肥指标体系有待更新、推广力度应持续加强、基层技术人员不足等方面的问题,并展望了测土配方施肥工作的前景,应更注重于探索多元化科学施肥、加强农技推广部门与科研单位合作、理论与创新相结合、推动大型合作社及肥料企业的交流合作等。

Soil Clinics: Farmers Teaching Smart-Farming to Farmers

In Thailand, the site-specific nutrient management technology, known as “Tailor-made Fertilizer Technology (TFT)”, for rice, maize and sugarcane in the Northeastern region was developed between 1997-2007, using the concepts of precision agriculture together with an approach of building capacity of small farmers. TFT, also called Smart-farming, comprises four components, namely 1) soil series identification, 2) N-P-K testing by soil test kit, 3) fertilizer recommendations using decision-aids and a simplified version of a complex model and 4) farmer empowerment. The benefit of TFT at the rice field of the Huay Kamin chairman farmer group was one example, the technology has been disseminated to the 80 members with a total planting area of about 320 ha. The results revealed chemical fertilizer reduction of 69%, and rice yield increased some 10% - 20% with the improved fertilizer application method. The farmers were encouraged to establish “Soil Clinics” in their communities. In a Soil Clinic, designated and trained farmer leaders analyze soil samples for member farmers and provide TFT recommendations while providing access to fertilizer materials available for sale at competitive prices. At present, there are about 70 soil clinics in 20 provinces with the support of many government and private sectors.

测土配方施肥项目十五年进展与展望

为系统总结测土配方施肥对我国科学施肥工作的重要贡献,对测土配方施肥项目实施15年的发展进程进行了归纳,划分为启动扩大阶段(2005~2009年)、整建制推进阶段(2010~2014年)、绿色发展阶段(2015~2019年)。利用国家测土配方施肥管理系统统计数据,研究了项目在构建我国土壤及作物肥效基础数据库、推动土壤肥料技术普及和提升农民科学施肥水平等方面取得的成效。结果表明,15年来测土配方施肥项目累计采集土壤样品2046.7万个、植株样品152.6万个,分析土壤样品1833.9万个、植株样品129.9万个,开展小区试验40.3万个、大田示范76.7万个,发布肥料配方31.1万个,培训农民3.26亿人次,化肥施用总量和单位面积化肥用量分别较峰值下降10.3%和10.1%,氮肥利用率提升11.7个百分点,2019年实现测土配方施肥推广面积1.38亿hm2。测土配方施肥项目成效显著,但在管理、技术等方面仍存在一些问题,特别是在测试化验、推荐施肥指标体系、技术物化、高效施肥技术推广等方面仍有改进和提升的空间,建议围绕农业绿色发展主线,进一步夯实测土配方施肥基础性工作,加强高效肥料品种和施肥技术的研发,强化技术推广,服务乡村振兴战略实施。

砾石土料的湿化变形试验技术难点与解决方法

砾石土心墙料的大尺寸样品湿化变形试验难度极大,这主要是砾石土料的性质决定了其饱和固结排水困难、样品难以达到饱和状态、试验周期太长。从试验技术、测试方法等方面进行攻关,分析试验成果出现偏差的原因并修正,针对砾石土湿化变形离散性大、存在应力饱和问题,进行了艰难地研究探索。通过对湿化试验过程中的体变修正、进水量修正、饱和度实时计算、成果离散性处理等关键细节的严格把控,最终成功地完成了典型砾石土料的湿化变形试验,获得了规律性较好的砾石土心墙料湿化变形成果。试验过程中出现的异于常规的现象,如围压施加过程中三轴压力室的整体向上变形、高应力状态下没有湿化变形量等,通过试验数据分析和理论分析,最终都得到了合理的解释,加深了对砾石土心墙料土工试验技术和砾石土料湿化变形的认识。

非饱和土力学特性及本构模型

地表土几乎全是非饱和土,特别是在干旱和半干旱地区,用饱和土力学理论和实验手段不能正确解释和处理非饱和土工程问题。首先介绍用低吸力和高吸力分别描述土的非饱和程度;简单回顾饱和土力学理论之后介绍现在比较认可的非饱和土力学理论;介绍低吸力下非饱和土持水和力学性质的测试方法,重点说明因使用陶土板而需要注意事项与对策以及非饱和土三轴仪的体积测量方法;用吸力控制压缩试验、三轴试验和真三轴试验的实测结果说明非饱和土的典型力学性质;根据试验结果分析持水曲线的直接影响因素和持水与力学性质的耦合特性,用弹塑性方法建立非饱和土持水和力学特性耦合的本构模型,并用吸力控制或量测的等向压缩和三轴试验结果验证;开发高吸力范围内吸力控制三轴试验方法,用该方法获得广吸力范围内4种典型土的应力应变关系,并用其中两种广吸力范围内强度数据对各种非饱和土强度计算公式的适用性进行分析。

生计分化对农户环境友好型技术采纳的决策行为的影响研究

基于江西省1092户农户的微观数据,从当前农村社会农户生计分化这一突出现象切入,运用Triple-Hurdle模型,从自然、人力、社会、物质、金融、生态和心理7个维度,分析生计资本对农户环境友好型技术的采纳意愿、采纳行为以及采纳程度3个阶段决策行为的影响。结果表明:(1)有测土配方施肥技术采纳意愿的农户占样本总数的81.96%,其中24.13%的农户有采纳行为,并且采纳程度为91.60%,仍有较大提升空间。(2)农户的技术采纳意愿、采纳行为与采纳程度受到7项生计资本的综合影响且具有一定的差异性。(3)人力资本和社会资本对农户环境友好型技术采纳行为影响较小,社会资本和生态资本对农户采纳程度影响较小。基于此,建议加大对农田水利与农村教育的投入,健全和完善土地流转制度,提高对大型农机具的购置补贴,推广使用节能产品,加强相关技术宣传力度,完善示范、培训、推广体系建设,针对各类农户制定相应的技术服务措施,促进农户意愿向行为转化。

农户绿色生产技术采纳的邻里效应分析——基于农技推广和农户认知的调节作用

研究目的:以测土配方施肥技术为例,探究农户采纳绿色生产技术行为的邻里效应,分析农技推广与农户认知在农户邻里效应中的调节作用,为加快绿色生产技术推广政策落地提供参考。研究方法:内生转换Probit模型。研究结果:(1)农户测土配方施肥技术采纳行为中存在明显的邻里效应,邻里效应中群体学习、交流机会显著正向促进农户采纳测土配方施肥技术;(2)农技推广对农户测土配方施肥技术采纳行为中邻里效应有显著正向和负向调节作用,农户认知对农户测土配方施肥技术采纳行为中邻里效应有显著负向调节作用;(3)农户具有技术接纳者和技术传播者的“双重身份”,且技术采纳可将邻里效应中群体学习、社会规范、交流机会的概率分别提升3.65%、3.82%、4.12%。研究结论:为了促进农户对绿色生产技术的采纳,建议培养农业生产示范户,充分发挥邻里效应;深化多元政企合作,形成技术扩散乘数效应。