Strategic deep tillage of deep sand soils impacts the sorption and biological availability of trifluralin

The phytotoxicity of soil-applied herbicides is enhanced in the first-year post strategic deep tillage

The decreasing number of places suitable for constructing buildings forces people to creatively develop newer methods of soil reinforcement. One of these methods is the deep soil mixing. This technology has been firstly developed and applied in Japan in the 1970s. Initially, it was used to create DSM (Deep Soil Mixing) columns. In the subsequent years, it was also developed in Scandinavia. Over time, the deep mixing technology was modified and developed, and in addition to the wet method, also the dry method was started to be used, while in addition to the cement binder, also lime binders and fly ashes were used. Technologies consisting of the deep mixing of cement with soil are very popular due to the wide range of applications and relatively low implementation costs. The method of Mass Stabilization (MS) is a soil reinforcement method that is analogical to DSM and it consists of mixing large volumes of soil with cement. This article describes the method of dry Mass Stabilization of organic soils. It cites the analyzed laboratory tests of soil-cement material manufactured in MS technology. The tests included the creation of 140 material samples, and subsequently the performance of compression strength test on them, along with the registration of stress path. The main aspect of these tests consisted of increase in the primary deformation modulus over time, depending on the amount of applied cement. Also, an example of the project to strengthen the layer of aggregate mud under the floor in the hall is demonstrated. The reinforcement was implemented in the MS technology.

In this paper, the impact and control of the triple shaft deep soil mixing (DSM) process is investigated by in situ experiments to reduce the displacement of adjacent tunnel. The modified construction parameters are presented in the project to minimize the installation effects of DSM by controlling water-cement ratio, the construction rate and spray process. The pore water pressure and soil displacement are measured during a single DSM column construction. Field test results show that the pore water pressure increases and diffuses, but the movement of surrounding soil is very little and almost keep in balance. A series of tests are carried out to compare the effects of the modified method with the traditional one, which shows that heave of adjacent tunnel caused by modified method is much less. Large-scale soil improvement in the project confirms that the deformation of running tunnels incurred by DSM is controlled within a little value.

Strategic deep tillage (SDT) practices, such as soil mixing following the application of soil amendments, are promising approaches to alleviate topsoil water repellence and other subsoil constraints and improve crop productivity. However, there is a lack of knowledge on the effect of SDT on soil water dynamics, especially under water-limited environments. This study evaluates the effects of clay incorporation, soil inversion and deep soil mixing on soil water infiltration, surface evaporation rates, soil water storage and subsequent impacts on the below and aboveground growth of wheat (Triticum aestivum L. var Scepter) in controlled environments. Results show that soil mixing significantly improved water infiltration compared to an untreated control. Clay incorporation exhibited the highest bare soil surface evaporation rates immediately and two years post-tillage, leading to substantial water losses under warm and dry ambient conditions. Despite improving soil water storage in deeper layers, high evaporation rates in clay-incorporated soils negatively impacted wheat growth, with reduced shoot biomass and root length density. Conversely, soil inversion and mixing-only treatments demonstrated balanced improvements in water infiltration, soil water use, and wheat shoot biomass. These findings underscore the trade-offs associated with SDT practices, particularly in managing soil water loss and crop productivity in water-limited environments. This study also highlights the need for the careful selection of SDT for soil amelioration strategies tailored to soil types and climatic conditions to enhance agricultural productivity and sustainability.

Liquefaction during earthquakes can result in severe damage to structures, primarily from excess pore water pressure generation and subsoil softening. Deep Soil Mixing (DSM) is a common method of soil improvement and is also used to decrease shear stress in liquefiable soils to control liquefaction. The current study evaluated the effect of Deep Soil Mixing (DSM) columns and implementation of different column patterns on controlling liquefaction and decreasing settlement of shallow foundations. A series of shaking table physical modelling tests were conducted for three different distribution patterns of Deep Soil Mixing (DSM) columns (i.e.: square, triangular and single) with a treatment area ratio of 30%. The treatment was applied to a liquefiable soil under a shallow model foundation. The results showed that the excess pore water pressure decreased 20% to 50% in comparison with the unimproved soil, depending on the Deep Soil Mixing (DSM) column pattern used. For improved soil, the shallow foundation settlement was about 10% that of the unimproved soil in the best case. The increase in soil shear stiffness after use of the Deep Soil Mixing (DSM) columns was compared with the results of existing practical relations to increase soil shear strength.

Peat represents an extreme form of soft soil and it poses serious problems in construction due to its long-term consolidation settlement even when subjected to a moderate load. Hence, suitable geotechnical design parameters and construction techniques are needed for this type of ground condition. Deep soil mixing (DSM) method is one of the widely used chemical methods of ground improvement for soft clay. However, DSM technique is quiet new for peat. Hence, aim of this research was to study the compressibility behaviour of peat stabilized with fly ash using DSM technique. A series of Rowe Cell consolidation experiments was conducted on peat and peat stabilized with fly ash. For the stabilization, 50% of fly ash was added to peat and single and multiple deep mixing columns were formed. Based on the outcome of this research, it was noticed that compressibility parameters such as compression index (Cc) and swell index (Cs) reduce with the addition of fly ash. Percentage reductions in Cc by the addition of stabilized single and multiple columns (for column area ratio of 16%) were 27.3% and 39.4% respectively compared to raw peat, while the reductions in Cs were 37.6% and 62.5% respectively for single and multiple columns. In addition, it was noticed that shear strength parameters of peat (c' and φ') can be significantly improved by stabilizing with fly ash. On the whole, DSM technique is applicable for peat, and for a given area ratio, multiple DSM columns are more effective in reducing the compressibility compared to asingle DSM column.

Purpose In an ongoing construction project for a power plant, deep soil mixing (DSM) in a block configuration was proposed to reduce settlement and enhance the bearing capacity of weak subsoil. Given its critical importance for seismic performance under near-fault ground motions, this study aims to evaluate the dynamic response of DSM-improved soils subjected to various seismic excitations, including Ricker waves with varying amplitudes and frequencies, as well as unidirectional and bidirectional near-fault earthquakes, both with and without velocity pulses. The investigation focuses on the influence of key parameters such as incident angle, burial depth, DSM block width, thickness and interaction between DSM-soil-DSM. Additionally, considering the uncertainties in the geotechnical and structural parameters affecting seismic behavior, mathematical and statistical techniques are employed to develop metamodels that provide insight into DSM performance and enable sensitivity analysis of seismic responses. Design/methodology/approach Two-dimensional elastic finite element models were developed using GID software (version 14.0.2) based on project dimensions, followed by dynamic analyses performed in OpenSees (version 3.5.0). Soil and improved soil properties derived from laboratory tests were assigned to the finite element models. Lateral and bottom boundaries were modeled as semi-infinite to minimize boundary effects. Statistical analyses and metamodeling were conducted using Design-Expert software (version 12) to account for uncertainties in seismic response parameters. Findings The results of this study demonstrated that DSM can significantly influence horizontal and vertical accelerations at the ground surface. Increasing the DSM thickness led to a reduction in horizontal accelerations but caused an increase in vertical accelerations due to rocking motion. Therefore, increasing the DSM thickness beyond one-quarter of the soil's shear wavelength is not recommended. The presence of DSM or increasing its thickness had no considerable effect on reducing vertical accelerations. Although increasing the DSM width did not reduce horizontal accelerations, it proved an effective measure for controlling rocking motion. A width increase of more than 1.5 times the initial value is not recommended due to decreased efficiency and increased implementation costs. Given the significant influence of block-type DSM on the surrounding soil, evaluating DSM–soil and DSM–soil–DSM interactions is essential. Furthermore, applying bidirectional seismic loading led to a considerable increase in vertical accelerations. Practical implications In this study, the seismic performance of the block DSM method has been comprehensively investigated. The effects of various parameters under different loading conditions have been analysed. The results of this research can provide valuable insights to engineers for a better understanding of the behavior of this soil improvement technique. Originality/value This research was conducted based on real data from an ongoing power plant project and systematically investigated the key parameters influencing the seismic behavior of improved soils. The findings provide practical guidance for optimizing design and enhancing the understanding of the seismic performance of DSM systems.

Deep mixing method, the ideal choice that can be used to treat problems arising from the presence of soft clay soil as a basis for constructing a specific structure. Soft clay soil covers large areas in some countries around the world, making it difficult to find suitable places for construction. Soft clay soil which has a high moisture content that makes it with small shear resistance and high settlement capability is not suitable as a bearing layer under the foundations of the facilities, Therefore, the need arose to either the use of a certain type of foundation, such as deep foundations Which are more complicated compared to the second option, or the use a specific treatment technique to improve the properties of the soft clay soil and make it suitable for the construction with the using of a certain type of foundations other than deep foundations. One of the most suitable treatment techniques for soft clay soils in terms of structural purpose, cost and time is the deep mixing process. Deep soil mixing is a complex process in terms of factors that affect the improved soil quality and the processes that causing the improvement. This process has been covered in a lot of books and published researches in many of its aspects, but there is some of that relates to this process has not been significantly highlighted such as improved soil permanence over time, which causes a poor understanding of the behavior of improved soil after the improvement process. In this research paper, everything related to the deep mixing process will be touch upon, starting with the historical development of this process, its beginnings to its types, classifications and applications, and the accompanying chemical and physical processes, in addition to a literary review for what related to this process.

Deep soil mixing (DSM) has become a widely used ground improvement technique globally, producing soil-cementitious materials for various complex civil and environmental applications. In the field, the soil-cement materials form under confining stress conditions, which are often overlooked, as most wet grab specimens are cured and tested under ambient atmospheric conditions. This oversight has led to an underestimation of the engineering and mechanical properties of the soil-cement mixed material. With support from the DFI Technical Committee Project Fund, the authors initiated a multi-phased comprehensive research study in collaboration with industry experts to gain a fundamental understanding of these effects. This study investigates the curing conditions to which in-situ materials are exposed and how these conditions influence the strength of deep mixed materials. The findings reveal that the curing conditions for in-situ materials, including applied stresses and temperatures, significantly differ from those under which typical quality control specimens are cured. Neglecting these conditions can lead to a substantial underestimation of in-situ material strength. The data compiled for this study encompass strength and temperature data obtained from specially designed laboratory bench tests, field-conducted modified oedometer tests, in-situ instrumentation tests within deep mixed columns, and a review of independent coring data from deep mixed projects across North America. Analysis of these collective studies reveals a correlation between curing stress and unconfined compressive strength (UCS). The rate of strength gains follows a linear pattern and is influenced by the soil type being treated. Fine-grain soils, in particular, exhibit a higher rate of strength gain when subjected to in-situ curing stress (with depth) compared to granular soils. The paper delves into fundamental processes such as drainage, consolidation, and interparticle behaviors of deep mixed materials from their fresh state until the treated column has cured. It also presents empirical and analytical methods to correct in-situ strength measurements to account for the effects of curing stresses.

To understand the effects of deep tillage on the yield and yield composition of maize on national and regional scales, we collected data from 1998 to 2023 of published papers in China and abroad. We conducted a meta-analysis, and quantified the overall and regional impacts of deep tillage on maize yield and yield composition, with conventional tillage (e.g. plow tillage, rotary tillage or harrow tillage with the depth less than 18 cm) as the control group and deep tillage (e.g. subsoiling, deep ploughing or deep mixing with the depth more than 25 cm) as the treatment. We further quantitatively analyzed the effect of annual average temperature, annual average precipita-tion, soil texture, pH, soil organic carbon (SOC) content, total nitrogen (TN) content, planting method, cropping system, straw returning, experimental duration, and fertilizer application on maize yield of deep tillage. Results showed that deep tillage significantly increased maize yield by 8.1% on the national level. Responses of yield to deep tillage in different regions were highly variable. Deep tillage significantly increased maize yield by 9.2%, 8.1%, and 7.8% in Northwestern, Northeastern, and Northern China, respectively. There was no significant difference for yield effect of maize in Southeastern China and Southwestern China. The significant increase in maize yield through deep tillage was attributed to the combined improvement in effective number of spikes, the grains per spike and hundred grains weight. Random forest analysis showed that experimental duration had greatest impact on the relative change rate of maize yield, accounting for 13.3%. Deep tillage could improve maize yield in the Northwes-tern China under one crop per annum and continuous cropping with the annual average temperature, annual precipitation, SOC and TN content was less than 10 ℃, 400 mm, 10 g·kg-1 and 1 g·kg-1, respectively. In climate zones with an average annual temperature of less than 10 ℃ and an average annual precipitation of 400-800 mm, as well as neutral (pH 6.5-8) soils with moderate soil nutrient content (SOC of 10-15 g·kg-1 and TN of 1-1.5 g·kg-1), deep tillage could increase maize yield in Northeast China during continuous cropping of one crop per year. In the neutral soil with an average annual temperature of 10-15 ℃, an average annual precipitation of 400-800 mm, SOC content＜10 g·kg-1 and TN content of 1-1.5 g·kg-1, where two crop rotation was used in the Northern China region, deep tillage significantly increased maize yield. The higher mean annual temperature may be the main reason for the insignificant yield increase of deep tillage maize in Southern China. The average yield increasing rate decreased with the extension of deep tillage duration. Yield effect reached the maximum when deep tillage lasted for 1-3 years. Straw returning and reasonable fertilization were the best methods increasing maize yield under deep tillage. Therefore, deep tillage would benefit maize yield in Northern China. The duration of continuous deep tillage should not exceed three years in combination with straw returning and suitable fertilization.

This paper discusses the influence of adding various amounts of cement to and changing the water content of clayey soil and their effects on controlling the settlement of a superstructure with various improvement area ratios (IARs). As a first step, the physical and mechanical properties of clayey soil from Bandar Imam Port, Iran, with 4, 6, 8 and 10% cement content and various water contents (30, 48 and 70%) were determined. Sample preparation was carried out using the wet deep soil mixing (DSM) method. The relationship between secant modulus at 50% strength (E50) and curing time for various cement contents was determined. In addition, different DSM column patterns with IARs of 0, 0·2, 0·3, 0·4 and 0·5, considering floating and end bearing DSM columns, were modelled using the finite-element method. Soil improvement by mass mixing of layers 2–7 m thick was also studied. The optimisation of various IARs and DSM characteristics and patterns enables production of a chart guide for preliminary design.

In many parts of the world, the earth has been heavily compacted as a result of large farm equipment. For soil compaction, the main constituent factors were soil physiochemical properties such as soil texture, moisture content, electrical conductivity, cation exchange capacity, total organic carbon, organic matter, total nitrogen, and soil pH directly and indirectly. This article addressed the causes and effects of soil compaction, operating parameters, and soil physicochemical properties in the Bishoftu long year tilled farmland of Ethiopia. For the experimental test, 5 different depths (5, 10, 15, 20, and 25 cm) and fifteen sample points were selected in 0.6 ha of 60 m by 100 m farmland for taking soil compaction data. Soil samples are taken from three depth ranges (0–10, 10–20, and 20–30 cm) from farmlands for investigation of soil physicochemical properties. The maximum and minimum values of the cone index of this study were 1918.133 kPa and 864.733 kPa, respectively, by taking the average of all sample points. The soil laboratory result shows that Bishoftu farmland soil is a mixture of loam, clay loam, and sandy clay loam with 47.33% of sand, 25.67% of clay, and 27% of silt. The maximum and minimum percentages of soil moisture values were 27.02 and 21.46 at 0–10 cm and 20–30 cm depth, respectively. Total organic carbon, organic matter, and total nitrogen exhibit positive relationships with depth and soil compaction. The correlation analysis indicates soil pH, electric conductivity, percentage of sand, cation exchange capacity, organic matter, and total nitrogen were among soil physiochemical parameters that are positively correlated with soil compaction. Furthermore, the percentage of clay, percentage of silt, and total organic carbon ( p ≤ 0.05 ) are negatively correlated with soil compaction in soil samples.

Soil amelioration via strategic deep tillage is occasionally utilized within conservation tillage systems to alleviate soil constraints, but its impact on weed seed burial and subsequent growth within the agronomic system is poorly understood. This study assessed the effects of different strategic deep-tillage practices, including soil loosening (deep ripping), soil mixing (rotary spading), or soil inversion (moldboard plow), on weed seed burial and subsequent weed growth, compared with a no-till control. The tillage practices were applied in 2019 at Yerecoin and Darkan, WA, and data on weed seed burial and growth were collected during the following 3-yr winter crop rotation (2019 to 2021). Soil inversion buried 89% of rigid ryegrass (Lolium rigidum Gaudin) and ripgut brome (Bromus diandrus Roth) seeds to a depth of 10 to 20 cm at both sites, while soil loosening and mixing left between 31% and 91% of the seeds in the top 0 to 10 cm of soil, with broad variation between sites. Few seeds were buried beyond 20 cm despite tillage working depths exceeding 30 cm at both sites. Soil inversion reduced the density of L. rigidum to <1 plant m−2 for 3 yr after strategic tillage. Bromus diandrus density was initially reduced to 0 to 1 plant m−2 by soil inversion, but increased to 4 plants m−2 at Yerecoin in 2020 and 147 plants at Darkan in 2021. Soil loosening or mixing did not consistently decrease weed density. The field data were used to parameterize a model that predicted weed density following strategic tillage with greater accuracy for soil inversion than for loosening or mixing. The findings provide important insights into the effects of strategic deep tillage on weed management in conservational agricultural systems and demonstrate the potential of models for optimizing weed management strategies.

Expansive clay soil has high potential of swelling due to minerals content which bind water, therefore, soil improvement is required to stabilize the swelling behavior by add binder additive such as lime in deep soil mixing method (DSM). In this study, Finite Element model approach was performed with embankment provided on the top of expansive clay layer to provide bearing layer for road construction. As the deep soil mixing is applied on the subgrade (expansive clay layer), some model variation is performed such as diameter variation with 0.4m; 0.6m; 0.8m, depth variation with 5m; 6.5m; 8m and space variation 0.8 m;1.2m;1.6m; 2.4m. Area ratio parameter also used for ease understanding of deep soil mixing behavior with so many model variations provided. Analysis results shows that higher area ratio of deep soil mixing will provide lower displacement value either immediate displacement or consolidation displacement. Moreover, plot result of area ratio shows that area ratio of 0.4 provide effective value regarding consolidation displacement and duration.

Ground improvement methods such as Deep Soil Mixing (DSM) and Jet Grouting Piles (JGP), are widely used to stabilize soft soils in underground construction. However, DSM and JGP construction processes themselves cause movements and pore water pressure changes in the adjacent ground, and can potentially impact adjacent structures. To mitigate these detrimental effects, the mechanisms of ground movements during DSM and JGP processes need to be well understood and controlled during construction. This paper summarizes data from a deep excavation within underconsolidated marine clays, where DSM and JGP were designed to stabilize the excavation. Field measurements show that significant ground movements and wall deflections occurred during DSM and JGP installation (prior to excavation). We have simulated the ground improvement processes using simplified 2D finite element analyses. The analyses assume a net volume change associated with deep soil mixing (reflecting pressure differences between the wet ‘soilcrete’ and surrounding clay), while much larger movements occur due to jet grouting in the space between the previously installed DSM columns and the perimeter diaphragm wall panels. This behavior is reasonably simulated by introducing a set of boundary pressures to represent JGP construction. Further research is now needed to establish how the jet grouting process can be controlled to limit potential ground movements in very soft clays.