In situ digital testing method for quality assessment of soft soil improvement with polyurethane

This study purposes an in situ testing method on quality assessment of soil improvement.Factual drilling data includes the spatial distribution and in situ strength of untreated and treated soil along three different drillholes measured by on-site drilling monitoring method.These factual drilling data can characterize the degree of soil improvement by penetration injection with permeable polyurethane.Result from on-site drilling monitoring shows that the linear zones represent constant drilling speeds shown in the plot of drill bit advancement vs.net drilling time,which indicates the spatial distributions of soil profile.The soil profile at the study site is composed of four layers,which includes fill,untreated silty clay,treated silty clay,and mucky soil.The results of soil profile are verified by the parallel site loggings.The constant drilling speeds profile the coring-resistant strength of drilled soils.By comparing with the untreated silty clay,the constant drilling speeds of the treated silty clay have been decreased by 13.0-62.8%.Two drilling-speed-based indices of 61.2%and 65.6%are proposed to assess the decreased average drilling speed and the increased in situ strength of treated silty clay.Laboratory tests,i.e.uniaxial compressive strength(UCS)test,have been performed with core sample to investigate and characterize in situ strength by comparing that with drilling speeds.Results show that the average predicted strengths of treated silty clay are 2.4-6.9 times higher than the average measured strength of untreated silty clay.The UCS-based indices of 374.5%and 344.2%verified the quality assessment(QA)results by this new in situ method.This method provides a cost-effective tool for quality assessment of soil improvement by utilizing the digital drilling data.

Effects of Microbial Fertilizers on Soil Improvement and Wheat Growth Characteristics in Saline-alkali Land

[Objectives]This study was conducted to further enrich the research on saline-alkali land improvement,and explore the effects of biological bacterial fertilizers containing Bacillus subtilis and Bacillus velezensis HM-3 in saline-alkali land improvement and crop growth promotion.[Methods]Wheat was planted in saline-alkali land in Huanghua City,Hebei Province,and a mixed application experiment was carried out using biological agents from Hemiao Biotechnology Co.,Ltd.[Results]Compared with the field of control check(CK),water-soluble salts and pH value in the experimental fields decreased,and living bacteria count in the soil increased.Meanwhile,the economic characters of wheat in the experimental fields showed excellent performance,with yields increasing by 39.09%and 27.49%compared with the CK.It could be seen that the application of biological bacterial fertilizers achieved obvious effects of improving saline-alkali soil and increasing wheat yield.[Conclusions]In this study,the effects of biological bacterial fertilizers on saline-alkali land and wheat growth characters were clarified,providing some technical support and theoretical guidance for wheat planting in Huanghua saline-alkali land.

An Overview of Soil Improvement through Ground Grouting

Soil is an essential component of what surrounds us in nature, providing as the basis for our infrastructure and construction. However, soil is not always suitable for construction due to a variety of geotechnical issues such as inadequate bearing capacity, excessive settlement, and liquefaction susceptibility. Through improving the engineering qualities of soil, such as strength, permeability, and stability, ground grouting is a specific geotechnical method used. Using a fluid grout mixture injected into the subsurface, holes are filled and weak or loose strata are solidified as the material seeps into the soil matrix. The approach’s adaptability in addressing soil-related issues has made it more well-known in the fields of civil engineering and construction. In the end, this has improved groundwater management, foundation support, and overall geotechnical performance.

Effects of Biochar on Tobacco-planting Soil Improvement and Tobacco Quality in Mudanjiang Area

This study was conducted to study the feasibility of biochar in soil im- provement and tobacco quality. The black soil in NinganCountry of Mudanjiang was used as the material in this study, and the effects of biochar on tobacco-planting soil C/N, soil microorganisms, the development of tobacco, and chemical compo- nents and neutral aroma components in flue-cured tobacco werestudied. The results showed that the application of biochar at a rate of 1 800 kg/hm2 could increase soil C/N by 31.79%, and the quantity of actinomycetes in the soil was 3.8 times as much as that in control. The growth wasobviously better after biochar application, plant height and effective leaf number were significantly higher than those ofcontrol, but total sugar and nicotine were not significantly different. The application of biochar at a rate of 1 200 kg/hm2 increased the potassium content by 11%, the application of biochar at a rate of 2 400 kg/hm2 improved total sugar content by 5.40%, and the application of biochar at a rate of 1 800 kg/hm2 made the tobacco solanone content 1.97 times as that of control. Comprehensive studies showed that the application of biochar 1 200-1 800 kg/hm2 could improvesoilenvironment, and promote tobacco growth and quality.

Steel Slag as an Iron Fertilizer for Corn Growth and Soil Improvement in a Pot Experiment

The feasibility of steel slag used as an iron fertilizer was studied in a pot experiment with corn. Slag alone or acidified slag was added to two Fe-deficient calcareous soils at different rates. Results showed that moderate rates (10 and 20 g kg-1) of slag or acidified slag substantially increased corn dry matter yield and Fe uptake. Application of steel slag increased the residual concentration of ammonium bicarbonate-diethylenetriamine pentaacetic acid (AB-DTPA) extractable Fe in the soils. The increase of extractable Fe was usually proportional to the application rate, and enhanced by the acidification of slag. Steel slag appeared to be a promising and inexpensive source of Fe to alleviate crop Fe chlorosis in Fe-deficient calcareous soils.

Biological process of soil improvement in civil engineering:A review

The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and environmental sustainability. This paper presents a review on the soil microorganisms responsible for this process, and factors that affect their metabolic activities and geometric compatibility with the soil particle sizes. Two mechanisms of biomineralization, i.e. biologically controlled and biologically induced mineralization, were also discussed. Environmental and other factors that may be encountered in situ during microbially induced calcite precipitation （MICP） and their influences on the process were identified and presented. Improvements in the engineering properties of soil such as strength/stiffness and permeability as evaluated in some studies were explored. Potential applications of the process in geotechnical engineering and the challenges of field application of the process were identified.

Functions of Russian Melilotus officinalis on Degraded Soil Improvement

To improve the serious situation of soil degradation in China, tests were carried out to study the improvement effects of Russian Melilotus officinalis on the low base saturation acid soil, the alkaline-saline soil and the heavy metal contaminated soil. The results showed that M. officinalis could improve the low base saturation acid soil, increase the salt, alkali content, mineral nutrition and organic nutrient, which indicated that M. officinalis could be planted in the acid soil, and had a significant ecological effect on soil improvement. M. officinalis achieved a remarkable effect on improving the alkaline-saline soil （pH 8.5-9.5） that the soil desalted, dealkalized and had more organic nutrient. Moreover, M. officinalis could improve the heavy metal contaminated soil and had the ability to enrich and transform heavy metal elements, especially Cd and Ni, thereby presenting significant repair effects on soil improvement. Therefore, Russian M. officinalis had multiple-effects on degraded soil improvement, so it is worthy of application and popularization.

Experimental study on soil improvement with stone columns and granular blankets

Stone column is one of the soil stabilizing methods that is used to increase bearing capacity and decrease the settlement of soft soils.Reinforced and unreinforced granular blankets are now being utilized to overcome the problems of soft soils.In this research,the bearing capacity of stone columns,granular blanket,and a combination of both methods in reinforced and unreinforced modes were studied using scaled physical models.Results show that using granular blanket,stone column,and combination of both improves bearing capacity of soft soils.Using geogrid as the reinforcement of granular blankets and geotextile as stone-column encasement increases the efficiency of granular blankets and stone columns significantly.Additionally,in the case of using geotextile around the stone column,the stress concentration ratio of the stone column will increase as well as its rigidity and bearing capacity.

Use of CCW （Civil Construction Waste） in Soil Improvement

The vast production of CCW （Civil Construction Waste） has caused socio-environmental concern as a result of the exploration of natural resources, clandestine disposal and proliferation of vector-borne diseases, for example. It now gives priority to non-generation, reduction and recycling of CCW. This study, therefore, seeks an alternative for CCW by comparing the physical and mechanical characteristics, both in laboratory and onsite, of the recycled CCW aggregate and natural aggregate （stone powder）, commonly used in the composition of compaction piles for improving soils in foundation works in the city of Recife, Pernambuco, Brazil. All results showed similar behaviours among the investigated samples （CCW recycled and natural）, confirming the satisfactory performance of the investigated CCW material.

A Study of the Effect of Soil Improvement Based on the Numerical Site Response Analysis of Natural Ground in Babol City

A series of numerical calculations have been performed to investigate the effect of soil improvement on seismic site response. Seismic site response analyses were also performed using data collected from a study area in Babol city. The improved site is a composite ground and has more or less different mechanical properties than the natural ground. In this research, the influence of the elastic modulus of the pile, the pile distance ratio, ground motion input, distance to fault rupture, and PGA of the earthquakes on seismic response characteristics are especially investigated. The results reveal that the values of the PGA and amplification factor on the surface of the natural and improved grounds depend strongly on the fundamental period of the site, the predominant period, and the intensity of the ground motion input. The acceleration response spectra also are affected by the characteristics of ground motion input and soil layers. Changing the pile distance ratio doesn’t have a significant effect on the seismic response of the site.

Study on Soil Improvement Measure of Plant Landscape Construction in Saline and Alkaline Area in Tianjin

A detailed research in soil improving measure was conducted during the process of plants that were cultivated in Tianjin saline and alkaline area. The results showed that the commonly used measures could improve the soil, and also we got some useful advices and suggestions for plants cultivating in Tianiin saline and alkaline areas.

Effects of Continuous Cropping on Soil Microbial Flora and Research Progress of Continuous Cropping Obstacle Reduction Techniques

Continuous cropping can bring economic benefits in a short time and meet the growing demand of agricultural products such as grain,but long-term continuous cropping will accelerate soil degradation,lead to the reduction of crop yield and the increase of disease rate,and destroy the balance of soil microbial structure.Therefore,it is not conducive to the sustainable development of soil ecosystem.In this paper,the problems caused by continuous cropping,such as imbalance of soil microbial flora,decrease of biodiversity,accumulation of root exudates and their effects on soil fertility and crop growth,were summarized,and some measures were suggested to alleviate the obstacles of continuous cropping,such as reasonable rotation,adjustment of intercropping planting mode and application of biological fertilizers.Moreover,the paper also looked forward to the development trend of continuous cropping obstacle reduction techniques,including the integration and application of biological techniques,the promotion of green ecological techniques and the application of intelligent management system.This study provides theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promote the healthy and sustainable development of modern agriculture.

Research Progress on Effects of Continuous Cropping on Soil Microbial Florae and Its Restoration

Continuous cropping has become a common form of agricultural production at present, but with the increase of continuous cropping years, continuous cropping obstacles such as soil-borne diseases and plant growth potential decline are becoming more and more common. At present, the causes of continuous cropping obstacles and continuous cropping restoration have become a hot issue in agricultural research. This paper summarized the effects of continuous cropping obstacles on soil microbial community structure and main technical methods to repair continuous cropping obstacles, such as agricultural measure management, microbial balance adjustment and soil improvement, aiming to provide theoretical reference for protecting the sustainable utilization of soil ecosystem and ensuring the stability of crop production.

Impact of Continuous Cropping on Soil Phenolic Acid Substances and Research Progress on Continuous Cropping Obstacle Reduction Techniques

At present,long-term continuous cropping in agricultural production has formed a relatively common development trend.With the increase of continuous cropping years,soil phenolic acids are also affected to varying degrees.This paper summarized the effects of continuous cropping on soil phenolic acids and the research progress of continuous cropping obstacle reduction techniques,aiming at providing theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promoting the healthy and sustainable development of modern agriculture.

Prospects and limitations of soil amendment and irrigation techniques for the water-saving public urban greenery and ephemeral weed management in the sandy soils of the United Arab Emirates

Public urban greenery greatly contributes to the residential and tourist value of cities in the Gulf Region,but due to the hyper-arid climatic conditions,the cost of irrigation and plant maintenance is very high.Existing strategies to reduce the monetary and ecological costs involve the cultivation of native xerophytic plantations,and/or the use of soil improvers to increase water-and nutrient-holding capacity of the sandy soils.Various soil improvers based on mineral,organic,or synthetic materials have entered the United Arab Emirates(UAE)market in recent years,but there is considerable uncertainty about how they should best be used in combination with ornamental plant stands involving xerophytic native plants.The present study investigated the effect of soil amendment and deep pipe irrigation on perennial ornamental plant stands involving native plants(Tephrosia appolinea(Gel.)Link in combination with Aerva javanica(Burm.f.)Juss.ex Schult.)and native-exotic plants(T.appolinea in combination with Ruelia simplex C.Wright)either or not topsoil and subsoil amendment with bentonite and hydrophobic sand under the irrigation water supply of less than 50%of reference evapotranspiration(ET0).After one year of cultivation,T.appolinea and A.javanica(native vs.native)produced high biomass and exhibited high water use efficiency(WUE)as compared with T.appolinea and R.simplex(native vs.exotic)combination given that no significant differences were found under the soil amendment treatments.All stands thrived under irrigation water supply far below what is usually supplied to exotic ornamental stands in public parks of the Al Ain City,the UAE.However,subsoil amendment in combination with deep pipe irrigation reduced the occurrence of weeds and increased the overall plant rooting depth.Our results suggest that subsoil amendment and irrigation up to 60-80 cm depth can potentially control ephemeral weed infestation,which is a great challenge in various plant production systems of the Gulf Region.The results of the present study suggest that the impact of soil amendment on the WUE of exotic plants is marginal and might not be economically justified.Replacing exotic with native ornamental plant species seems to have a far greater water-saving potential than the amendment of the soil,while weeds can be suppressed in the absence of topsoil moisture.

Improvement of geotechnical properties of sabkha soil utilizing cement kiln dust

Improvement of properties of weak soils in terms of strength,durability and cost is the key from engineering point of view.The weak soils could be stabilized using mechanical and/or chemical methods.Agents added during chemical stabilization could improve the engineering properties of treated soils.Stabilizers utilized have to satisfy noticeable performance,durability,low price,and can be easily implemented.Since cement kiln dust(CKD) is industrial by-product,it would be a noble task if this waste material could be utilized for stabilization of sabkha soil.This study investigates the feasibility of utilizing CKD for improving the properties of sabkha soil.Soil samples are prepared with 2% cement and 10%,20% or 30% CKD and are tested to determine their unconfined compressive strength(UCS),soaked California bearing ratio(CBR) and durability.Mechanism of stabilization is studied utilizing advanced techniques,such as the scanning electron microscope(SEM),energy dispersive X-ray analysis(EDX),backscattered electron image(BEI) and X-ray diffraction analysis(XRD).It is noted that the sabkha soil mixed with 2% cement and 30% CKD could be used as a sub-base material in rigid pavements.The incorporation of CKD leads to technical and economic benefits.

Emission control for precursors causing acid rain(V): Improvement of acid soil with the bio-briquette combustion ash

The bio-briquette technique which mixes coal, biomass and sulfur fixation agent and bio-briquettes under 3—5 t/cm 2 line pressure has aroused people's attention in view of controlling the air pollution and the acid rain. In this paper, the physicochemical properties of bio-briquette and its ash were investigated. And the acid soil was improved by the bio-briquette combustion ash, which contained nutritive substances such as P, N, K and had the acid-neutralizing capacity(ANC). The pH, EC, effective nutrient elements(Ca, Mg, K, P and N), heavy metal elements(Al, Cu, Cd, Cr, Zn and Mn) and acid-neutralizing capacity change of ash-added soils within the range of 0—10%, were also studied. Specially, when 5% bio-briquette combustion ash was added to the tested soil, the content of the effective elements such as Ca, Mg and K rose by 100 times, 7 times and twice, respectively. The total nitrogen also increased by about twice. The results showed the oxyanions such as that of Al, Cu, Cd, Cr, Zn and Mn were not potentially dangerous, because they were about the same as the averages of them in Chinese soil. It is shown that the ANC became stronger, though the ANC hardly increases in the ash-added soil. On the basis of the evaluation indices, it is concluded that the best mixture ratio is to add 2.5%—8% of the bio-briquette combustion ash to the tested soil.

Assessment of glass fiber-reinforced polyester pipe powder in soil improvement

This study investigates the use of glass fiber-reinforced polyester(GRP)pipe powder(PP)for improving the bearing capacity of sandy soils.After a series of direct share tests,the optimum PP addition for improving the bearing capacity of soils was found to be 12%.Then,using the optimum PP addition,the bearing capacity of the soil was estimated through a series of loading tests on a shallow foundation model placed in a test box.The bearing capacity of sandy soil was improved by up to 30.7%.The ratio of the depth of the PP-reinforced soil to the diameter of the foundation model(H/D)of 1.25 could sufficiently strengthen sandy soil when the optimum PP ratio was used.Microstructural analyses showed that the increase in the bearing capacity can be attributed to the chopped fibers in the PP and their multiaxial distribution in the soil.Besides improving the engineering properties of soils,using PP as an additive in soils would reduce the accumulation of the industrial waste,thus providing a twofold benefit.

The influence of hydrochar from biogas digestate on soil improvement and plant growth aspects

Hydrochar(HC),produced by hydrothermal carbonization,offers technical advantages over biochar(BC)produced by pyrolysis,and is suitable for soil amelioration,carbon sequestration,and enhanced plant growth.BC grain size has been shown to influence nutrient retention,microbial colonization and aggregate formation;however,similar research for HC is lacking.Pot trials were conducted to investigate the influence of HC grain size[coarse(6.3-2 mm),medium(2-0.63 mm)and fine(<0.63 mm)],produced from biogas digestate,for soil improvement in three soils:loamy Chernozem,sandy Podzol,and clayey Gleysol,at a 5%HC application rate(w/w).All soils including two controls(with and without plants)were analysed for water holding capacity(WHC),cation exchange capacity(CEC),wet aggregate stability,pH,plant available nutrients(PO_(4)-P,K and N_(min))and germination and biomass success using standard laboratory and statistical methods.Soil pH showed a compensatory shift toward the HC pH(7.2)in all soils over the course of the study.For example,the pH of the medium grained HC treatment for the Chernozem decreased from 7.9 to 7.2 and increased in the Podzol and Gleysol from 5.9 to 6.1 and 4.9 to 5.5,respectively.The nutrient-rich HC(2034±38.3 mg kg^(−1) PO_(4)-P and 2612.5±268.7 mg kg^(−1) K content)provided only a short-term supply of nutrients,due to the relatively easily mineralized fraction of HC,which allowed for quick nutrient release.The pH and PO_(4)-P effects were most pronounced in the fine grained HC treatments,with a~87%,~308%and~2500%increase in PO_(4)-P content in the Chernozem,Podzol and Gleysol,respectively,compared to the controls at the beginning of the study.The same trend was observed for the K and NH_(4)^(+)content in the fine and medium grained HC treatments in all soils.No seed germination inhibition of Chinese cabbage was observed,with average germina-tion rates>50%in all soils.An effect on NO_(3)^(−)content was indeterminable,while there was little to no effect on biomass production,WHC,CEC and aggregate stability.In conclusion,the application of 5%fine grained HC significantly influenced the nutrient content over a short-term.However,the application rate was insufficient to substantially improve plant growth,nor to sustain a longer-term nutrients supply,regardless of grain size.

Effects of Several Passivating Agents on Improvement of Cd Polluted Soil

Clay minerals,phosphates,alkaline materials,organic materials are common improvers in the management of Cd polluted soil. This paper systematically summarized types of common soil improvers and their passivation mechanism of Cd in soil. It reviewed advances in researches of soil improvers. Besides,it introduced major problems in four common passivating agents for management of Cd polluted soil. Finally,according to different mechanism characteristics of passivating agents,it came up with some recommendations.