Soil Swelling Research Articles

Comparative Study of Swelling Pressure in Expansive Soils considering Different Initial Water Contents and BOFS Stabilization

In terms of geotechnical engineering, swelling soils are among the most important soil groups whose characteristics should be determined in detail before design studies. These types of soils cause significant damage to engineering structures. For this reason, it is expected that the swelling behavior of the soils will be known in advance to minimize the damage that may occur in the structures. Within the scope of this study, the swelling pressures of bentonite clay with 10 different water content were determined by keeping all conditions the same to reveal the effect of water content on soil swelling behavior. In this context, bentonite-type (montmorillonite content) clay, which has a very swelling property when it comes in contact with water, was used in the experiments. The fixed volume swelling pressure test method was used in the experiments and all samples were compressed at the same rate and placed in the swelling test device. In all samples left to swell with pure water, measurements were made for 10 days and the effects of swelling pressures on the initial water content were discussed. Thereafter, another swelling soil was stabilized using basic oxygen furnace slag (BOFS) during different curing times, and after performing the swelling pressure test, the results were compared with the findings obtained from different initial water contents. According to the results, while the swelling pressures increase in the regions close to optimum water content, significant decreases are observed in swelling pressure values in wetter and drier regions than in optimum water content. Finally, the results indicated that the application of BOFS, albeit small, after the proper curing time can significantly affect the swelling behavior of bentonite, even more than changing the initial water content.

Sustainable Utilization of Calcium Carbide Residue along with Polypropylene Fiber Waste Materials for Accessing Swelling and Strength Characteristics of Black Cotton Soil

Due to industrialization and modernization, huge amount of waste generated by many industries causes a huge threat to the human health, environment and aqua life due to disposal problems. The present study focuses on utilizing industrial wastes to strengthen geotechnical properties of black cotton soil. The toxic compounds included in calcium carbide residue (CCR) created by the acetylene gas companies and polypropylene fiber made by the textile mills are both highly polluting. These materials can be utilized in soil stabilization alone and in combination in various proportions to obtain the finest subgrade material. The use of such industrial waste for subgrade soil stabilization is a cost-effective way of building pavements. This study examines the effects of addition of different percentages of CCR and fiber contents on Atterberg’s limits, compaction characteristics, unconfined compressive strength and California bearing ratio.

Determination of Diameter of Belled Shafts with respect to Uplift Forces Resulted From Expansive Soil Layer in Active Zone

Expansive soils are found in many parts of the world that are especially arid and semi-arid regions. They have caused several damages of lightweight structures for decades. For this reason, a more suitable foundation type should be selected and designed for the lightweight structures built on these soils. For example, the application of belled shaft foundation at expansive soil layer is preferable method in practice. However, one of the worst cases at the design of this foundation is accepted that the swelling of expansive soil placed in active zone. Therefore, this condition should be taken into account at the design process of this foundation. In this study, the diameter of belled shaft was separately determined with respect to some factors such as the diameter of shaft, the depth of active zone, the friction angle between shaft and soil, and the ratio between the undrained cohesion of soil at stable zone and the swelling pressure of expansive soil placed in active zone. In the calculation process, four different shaft diameters that are 0.3 m, 0. 45 m, 0.60 m, and 0.75 m were utilized. Also the depth of active zone that started from 1.5 m to 15 m was specified. To sum up, the optimum shaft diameter was found as 0.45 m.

PRE- FOUNDATION STUDIES USING VERTICAL ELECTRICAL SOUNDING AND SOIL SAMPLE ANALYSIS

Subsurface rock properties investigation to categories foundation competent layer for the proposed engineered structure capable of housing offices, lecture halls, and laboratories was carried out using geophysical (GPHY) and geotechnical (GTECH) techniques. Electrical resistivity GPHY technique using vertical electrical sounding (VES) field procedure was utilized in which nineteen (19) VES spots were occupied. Results of the VES revealed 2-D subsurface geoelectric sequences comprising of incompetent overburden layer of about 5 m thick with resistivity value between 10 and 210 ohm-m typical of clay soil material. Beneath this layer are sand formation and fresh bedrock with resistivity range of 750 to 1000 ohmm, which are good formations for foundation. Additionally, according to GPHY studies, western and northern portions of the region are marked by fractures/faults, which could cause building subsidence if foundation is stationed at these points. The results of the analyses of the soil samples taken in five different points in the study area revealed: (1) grain size distribution with 0.075 mm particle size passing of an average of 41% signifying the occurrence of clay, corroborating the presence of clay material within the weathered layer in GPHY investigations; (2) active and expansive nature of the soil with linear shrinkage greater than 8% revealing unsuitability of topsoil for foundation; (3) medium plasticity of soil indicating possible soil swelling; and (4) concomitant GTECH and GPHY results of the topsoil and weathered layer properties. The overburden layer with clayey materials must be removed and areas with geological structures must be taken into account.

Comparison of Two Sulfate-Bearing Soils Stabilized with Reactive Magnesia-Activated Ground Granulated Blast Furnace Slag: Swelling, Strength, and Mechanism

Sulfate-bearing soils, which causes many engineering problems, e.g., cracking, collapse, and pavement layer settlement, are often encountered in the construction of pavements. Ground granulated blast furnace slag (GGBS)-magnesia (MgO) has been regarded as an effective curing agent in the treatment of sulfate-bearing soil containing gypsum. However, field sulfate-bearing soils usually include other forms of sulfates, such as sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4). Currently, few studies have investigated the effect of the type of sulfate on the properties of sulfate-bearing soil stabilized with GGBS-MgO. In this study, GGBS-MgO was used to treat Ca-sulfate-soil and Mg-sulfate-soil. Swelling, unconfined compressive strength (UCS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) tests were employed to investigate the properties of the stabilized soils. The results showed that when suitable GGBS:MgO ratios were achieved, the swelling of the two types of sulfate-bearing soils could be well suppressed. However, the trend that the swelling varied with the decrease in the GGBS:MgO ratios was opposite between the two soils. The UCS of Mg-sulfate-soils was much lower than that of the Ca-sulfate-soils after the stabilization of GGBS-MgO irrespective of the curing or soaking stage. CSH significantly occurred in Ca-sulfated soils treated by GGBS-MgO. Ettringite was not observed in the soil with GGBS-MgO = 9:1 but was observed in 6:4. Compared to Ca-sulfate-soils, MSH and less CSH were formed in Mg-sulfate-soils stabilized with GGBS-MgO, which caused the lower strength of the stabilized Mg-sulfate-soils. No ettringite was formed in such soils. Hence, the sulfate type contained in the soils had a significant effect on the swelling and strength properties of sulfate-bearing soils with GGBS-MgO, and so the sulfate needs to be identified before the soil’s stabilization.

Swelling–shrinkage mechanisms of diatomaceous soil and its geohazard implication

Current understanding of soil behaviors from classic soil mechanics is constantly challenged by a variety of unusual soils, one of which is diatomaceous soils (DSs). It is well understood that this biological-origin soil has fundamentally different geotechnical features from that of common fine-grained soils because of the presence of diatom fossils. Recently, increasing geohazards and engineering disasters associated with DS swelling–shrinkage are reported but the exact role of diatoms in determining soil swelling–shrinkage, the underlying mechanisms, and the geohazard implications, have not yet been revealed. This study systematically investigates the swelling–shrinkage behavior of natural DS as well as artificial mixture of diatoms and clay minerals (kaolinite and montmorillonite). The swelling–shrinkage behaviors are explained from the perspectives of mineralogy and microstructure as revealed through X-ray diffraction, scanning electronic microscopy, and transmission electron microscopy. Diatoms have a special microstructure with inter-frustule pores, and the intra-skeletal and skeletal pores in DS make the soil characterized by a high void ratio and water content. In addition, the presence of diatoms curbs the swelling–shrinkage of DS but this may be overwhelmed by the high stress generated due to the swelling of montmorillonite. The wetting–drying cycles subjected to DS result in fissure development, a higher level of swelling–shrinkage behavior, and ultimately in related geohazards such as landslides. The distinct swelling–shrinkage behavior of DS makes the previous classification inapplicable; thus, more rational classification methods are adopted. This study enhances the understanding of the swelling–shrinkage behavior of DS and the control of related geohazards.

Effects of Climate Change on Geotechnical Infrastructures — state of the art

Geotechnical infrastructures, like slopes and embankments, retaining walls, foundations, engineered landfills, overburden dumps, and pavements, get continuously exposed to various environmental factors which are climate dependent. Fate/stability of these infrastructures due to extreme and abrupt change in precipitation, temperatures, humidity, and wind/airflow is quite questionable. Some of the issues related to climate change on soils include increase in infiltration rate, high pore-water pressure, decrease in effective stress, soil liquefaction, seepage failures, frost heaving, changes in soil suction potential, swelling and shrinkage in fine-grained soils, differential settlement, and damage to vegetation cover and thereby causing slope failures, waterlogged conditions, floods, soil erosion and/or internal erosion of fines, damage to landfill liners and soil covers, desertification, desiccation cracks on the ground surface, and groundwater table pollution due to contaminant migration. Therefore, studies on the impact of climate change on geotechnical infrastructures have gained attention of many researchers in the recent times. In present study, an up-to-date review of the works related to the influence of various climatic factors on geotechnical properties and thereby on geotechnical projects is carried out. Topics related to climate data downscaling using global climate models (GCM), climate change-induced slope instability, acid rains, desiccation cracking in soils with changing temperatures, impacts of dry-wet cycles and freeze-thaw cycles, and vegetation effects on soils are emphasized in this paper. Furthermore, to address the challenges, need-based research related to resilient infrastructures, thermo-hydro-mechanical models, bioremediation methods, innovative sustainable composite materials, and incorporation of climatic factors in design is highlighted and discussed.

Swelling Prediction in Compacted Soils Using Adaptive Neuro-Fuzzy Inference System

Swelling in compacted soils may lead to some damages to structures and buildings. For the sake of reducing such damages, soil swelling should be determined, so as to make the structures exhibit adequate resistance against such a phenomenon. For most cases, fully non-linear relations have been observed between soil swelling and the parameters contributing to swelling in compacted soil. As such, soil swelling should be determined via either experimentations or prediction models. However, being extremely timely, swelling tests require special expensive equipment. Accordingly, there is a need for models which can use available data to theoretically give swelling estimations of a relatively high accuracy without getting busy with swelling tests and associated issues. Investigated and evaluated in this research are the ability and application of an adaptive neuro-fuzzy interference system (ANFIS) developed by subtractive clustering and fuzzy c-mean clustering to determine and predict swelling in compacted soils. The results along with the obtained values of root mean squared error (RMSE), mean absolute error (MAE) and coefficient of correlation (R) indicated that the proposed ANFIS model succeeded to predict swelling in compacted soils at a good level of accuracy. Therefore, ANFIS models can be used to predict swelling without getting busy with swelling tests and associated issues. KEYWORDS: Swelling of compacted soil, Subtractive clustering, Fuzzy c-mean clustering, ANFIS, Prediction.

The Investigation of the Addition of Sodium Lignosulfonate to Lime Column Used For Improving the Expansive Soils

The lime column (LC) technique has been commonly used for the improvement of expansive soils. The achievement of this technique depends on the lime diffusion into the expansive soils, but lime diffusion into the expansive soil is generally a slow process due to the low permeability of these soils. In this study, sodium lignosulfonate, which is used as a superplasticizer in the concrete industry, was added to lime columns to accelerate the diffusion of lime particles. First, treated expansive clay specimens with thirty-seven 4.5 mm diameter columns were prepared in an oedometer ring. These columns were filled with two different mixtures: water-lime and water-lime-sodium lignosulphonate to investigate the effect of the addition of sodium lignosulphonate. Free swell tests were done on these treated expansive clay specimens that were subjected to different curing periods, it was observed that the treated specimens with sodium lignosulphonate lime columns (NaLS-LC) are more effective than the treated specimens with lime columns (LC). A treated expansive clay specimen (in a 30cmx30cm mold) with seven pieces of 45 mm diameter sodium lignosulphonate lime columns were prepared to observe the alteration of engineering properties of untreated expansive clay specimen (US) located between the columns. Free swell and unconfined compressive strength tests were done on the undisturbed expansive clay specimens taken from the mold between the columns. SEM-EDX analyses were made to investigate whether the ettringite mineral, which leads to swelling of the expansive soil during lime stabilization, forms or not. While the ettringite mineral formed during the curing period in the lime column stabilization method, the addition of sodium lignosulphonate to lime columns blocked the formation of the ettringite mineral. It can be stated that sodium lignosulphonate lime columns (NaLS-LC) show better performance than lime columns (LC), in the treatment of expansive clays.

Impact of rice husk ash and xanthan gum in road works by improving the characteristics of expansive soil (black cotton soil)– an inclusive study

The soils of Indian Black Cotton are well-known examples of Expansive soils, which display significant swelling and shrinkage in response to changes in moisture content. The distressing cyclical swelling and shrinking of soils under moisture fluctuations lead to serious failures. Stabilization of soil can be used to improve it in order to get around this. An agricultural industrial waste called rice husk ash is created when rice husk, a byproduct of paddy milling, is burned. In delta regions, it is widely distributed. It is a pozzolanic material that is widely distributed in India and has potential use in a number of geotechnical areas. In this stabilisation process, black cotton soil is mixed with RHA-lime and various percentages of cementitious material, particularly lime. Tests such as plasticity, compaction, swell, and CBR were also conducted with different water contents of OMCs (such as OMC + 2% water content and OMC + 5% water content). From the test findings, it can be concluded that adding lime reduces flexibility and increases strength. With the addition of RHA and lime, expansive soil gets higher CBR values at varied water contents more than 50% for dosages of 10% lime + 20% RHA and 10% lime + 30% RHA. The expansive soil becomes non-plastic, non-swelling, and has increased strengths, making it suitable for use as a building material for roads.

Strength and compaction characteristics of kaolin clay blended with industrial wastes

The long-term stability of the construction over soil depends significantly on the strength of the ground. Swelling and shrinkage characteristics of expansive fine-grained soil causes volumetric changes followed by distress and damage to the structures resting on it. One of the most popular and cost-effective methods of improving soil is adding admixtures. Utilization of industrial wastes in soil stabilization is a cost effective and environment friendly solution. In this study, two types of industrial wastes, copper slag and pond ash, are used with the aim of improving the strength and compaction characteristics of subgrade. So, the work is focused on evaluating the compaction and strength characteristics of Kaolin clay (KC) blended with Copper Slag (CS) and Pond Ash (PA). For the compaction characteristics, modified proctor compaction tests were conducted and to study the strength characteristics, Unconfined compressive strength (UCS) and split tensile strength (STS) tests were conducted. In Total, 14 different mix combinations were used in this study. From the test results, it has been observed that blending KC with PA and CS not only improved its compaction characteristics but strength too.

Analysis of climate change impacts on the shrinkage-swelling phenomenon of clayey soils to adapt infrastructures

As a tendency in France, the well-known shrinkage-swelling phenomenon of clayey soils intensifies naturally and durably under climate change effects after the severe droughts happened post 2015. More than 10.4 million houses are highly exposed to this phenomenon and the new national zoning shows that high or medium exposure now concerns 48% of the metropolitan soils. Roads are also severely impacted by the shrinkage-swelling phenomenon through damage characterized most often by longitudinal cracks close to the edges and very significant deformations that can be a danger for the safety of users. The aim of this research is first to understand how the natural unsaturated clay soils shrink and swell under numerous drying-wetting cycles using several devices at the laboratory scale. The second approach consist of several in situ experimentations of different techniques to reduce the shrinkage-swelling impact on unsaturated clay soils. The first results show that at the laboratory scale, the unsaturated clay soils can be significantly affected after some drying-wetting cycles. In the other hand, in situ monitoring results show that some techniques allow clay soils to save their hydromechanical properties at a hydric equilibrium state which can reduce settlement deformations. The main goal of these research works is to better understand how the shrinkage-swelling phenomenon of clayey soils evolves under climate change in order to develop the new solutions allowing the adaptation of the infrastructures.

Influence of compaction on the soil shrinkage and swelling curves

The behaviour of soils undergoing deformation due to changes in water content can be described using Soil Shrinkage Curves (SSCs). The SSCs are normally influenced by several factors as the soil’s fabric, different compaction levels, residual void ratio, and the shrinkage limit. In this study, shrinkage curves at different compaction levels were obtained using both wax coating and image analysis as volumetric quantification methods. Both techniques returned consistent results. To fit the obtained experimental data, a single equation is proposed with fitting parameters pertaining to the physical characteristics of the soil samples used. The use of Mercury Intrusion Porosimetry (MIP) is also incorporated to further analyse the structure of the soils being studied. The effect of the drying path on the structure was more apparent in the size range of 100-2000 nm. The effects of compaction on soil structure and shrinkage behaviour were also discussed in the study. The presented work provides valuable insights on the effect of different compaction levels on the soil shrinkage behaviour.

Effect of Emulsified Asphalt on Expansive Soil Strength and Swelling

Some clay soils classified as extended soils threaten the structures resting on them. Many additives are available to improve the properties of expanded soils. This study tries to investigate the consequences of wetting-drying cycles on the swelling behavior of modified expansive clayey soils under laboratory conditions by modifying expansive clayey soil samples using emulsified asphalt. Five different percentages of emulsified asphalt were used: (2, 4, 6, 8, and 10) %. The natural and treatment soils were tested for classification, specific gravity, compaction characteristics, free swell and swell pressure, consolidation, and compressive strength. The liquid limit and plasticity index have been lowered by adding Emulsified Asphalt. After that, the effects of Emulsified Asphalt on undrained shear strength characteristics (cohesion and friction angle) have been studied. The results revealed that when the emulsified asphalt content was increased to 10%, the swelling pressure and swelling potential decreased by 58 and 78 %, respectively. The swell and shrink improvement factor for the 10% emulsified asphalt addition is always larger than 75%. As the duration of wetting-drying cycles increased, the swelling pressure and swelling potential values were also reduced. The plastic limit, on the other hand, increased as the Emulsified Asphalt content increased. Increasing the amount of Emulsified Asphalt increased the maximum dry unit weight values, whereas the optimum water contents increased. It was concluded that emulsified asphalt stabilization may be useful for expansive clay as it improves compressive shear strength.

Healing behaviour of desiccation cracks in a clayey soil subjected to different wetting rates

Desiccation cracks initiate and propagate during the drying process and healing occurs during the wetting process. However, most of the previous studies only paid attention to the drying-induced crack propagation and the wetting-induced healing behaviour was always neglected. In this paper, a series of wetting tests were conducted on cracked soils under different wetting rates. The crack pattern evolution during wetting was recorded and quantitatively analysed. The results show that the narrow and short secondary and tertiary cracks heal earlier than the long and wide primary cracks during wetting. With the elapsed wetting time, the surface crack ratio and average crack width decrease slowly at first, then rapidly decrease and eventually stabilise. However, at the early stage of wetting, the total crack length almost remains constant. The healing of desiccation cracks in clayey soils is mainly attributed by two factors: wetting-induced swelling and disintegration. Furthermore, the healing degree of desiccation cracks become higher with increasing wetting rate. The healing of desiccation cracks with a lower wetting rate is mainly due to the wetting-induced swelling of soils. However, that with a higher wetting rate is dominated by both swelling and disintegration.

Improvement of swelling soil by using lime sludge and sodium chloride

Construction on swelling soil is a major challenge to geotechnical engineers all around the world. This type of soil has a quite complex behavior as they undergo the category of problematic soils. The seasonal variations in the climate cause swelling and shrinkage, affecting soil’s water retention. The prediction of future climate change will worsen this problem, increasing the importance of the matter. The attention has been directed to experimental modeling and field investigations. In previous references, this problem was targeted by adding additives which are relatively expensive and non-environment friendly. In this study, waste and recycled materials are used in the lab to enhance the undesirable expansive soil characteristics to keep the environment clean and sustainable and reduce pollution. The additives are selected not only for its availability and cheapness but also to reduce the damage of environment due to disposal of waste. Therefore, the aim of study is to observe the behavior of expansive soils when mixing with various percentages of sodium chloride (NaCl) and lime sludge (LS). The percentages used in this work to determine the swelling properties of expansive soil were 1%, 2%, and 3% NaCl by weight with 3%, 6%, 9%, 10%, 12%, 15%, and 20% of LS by weight. The experimental tests held in the laboratory were liquid limit (LL), plastic limit (PL), free swell (FS), plasticity index (PI), swelling pressure, swelling and infiltration test, and physical models. The results show that by increasing the percentage of NaCl and LS, a significant improvement is obvious to the swelling properties of soils. Added to that, a decrease in PI of the swelling soil is clearly observed which reflects a decrease in swelling pressure and free swell of the swelling soil.

Experimental Investigation on Black Cotton Soil Treated with Terrabind Chemical and Glass Powder

Abstract: Objectives: To improve the soil stability of Black Cotton (BC) soil which is abundantly found in East Godavari district and some costal areas of Andhra Pradesh in India as they are susceptible to detrimental volumetric changes, with changes in moisture. Methods: laboratory studies has been carried-out to investigate the influence of chemical called Terrabind on Balck Cotton (BC) soil from Amalapuram, East Godavari, Andhra Pradesh, and further the influence on BC when Terrabind is added in combination with Glass Powder (GP). Basic geotechnical properties like grain size distribution, specific gravity, consistency limits have been determined and engineering properties like Maximum Dry Density (MDD), Optimum Moisture Content (OMC), Unconfined compressive strength, California Bearing Ratio (CBR), and Triaxial compression test have been determined for untreated and treated soil. Swelling properties have been determined by conducting free swell index test and swell pressure test. The laboratory investigations were conducted for different curing days to determine the basic and engineering properties of soil such as Atterberg’s limits, grain-size distribution, MDD, OMC, CBR, Unconfined Compressive Strength (UCS), Strength, Durability, Fatigue and Resilient Modulus (E). Findings: There is no huge soil expansion in the consistency limits for the compound (which compound) treated BC soil. Untreated soil shows LL=63%, PL =32%, and PI =34%. For soil settled with Terrabind, PI has diminished from 28% for one day restoring to 24% for 28 days relieving period. For soil balanced out with Terrabind+GP, PI has diminished from 27 % for one day restoring to 18% for 28 days relieving period. Improvement in dry density of treated soil is peripheral. MDD expanded from 17.6 KN/m3 to 18.4 KN/m3 and 18.7 KN/m3, and OMC was decreased from 16.32% to 16.24% and 16.12% for soil settled with Terrabind and Terrabind + GP for 28 days restoring period individually. Swell strain test results showed that Swell tension diminished from 49.5 KN/m2 to 36.73 KN/m2 and 35.12 KN/m2 for soil settled with Terrabind and Terrabind+ GP tried following 7 days of restoring. Swell tension was decreased by 26% and 29% for soil settled with Terrabind and Terrabind+ GP individually. Novelty: Soil stabilized with Terrabind and GP has showed better results compared to soil stabilized with Terrabind. Percentage weight loss was less than 14% for 12th cycle of freeze- thaw, which shows that the stabilized soil has become durable. Swelling has reduced to a great extent. The swelling of soil stabilized with Terrabind and Glass Powder (GP) has reduced by 100%

Artificial macropores and water management effects on reduction of greenhouse gas emissions from rice paddy fields

Rice production is an important sector of global agriculture, sustaining more than half of the world's population. However, rice production contributes significantly to global warming through increased emission of greenhouse gasses (GHGs), primarily CH4, into the atmosphere. Therefore, this study examined countermeasures to reduce GHG emissions from paddy fields without affecting rice production. A column experiment was conducted to investigate the effects of soil macroporous structure and water management on GHG emissions from flooded alluvial clay soil (paddy soil). The soils were subjected to different management regimes: with and without artificial macropores, compost, and drainage treatment. Drainage was maintained at 6.5 mm d − 1 to ensure infiltration yet prevent excessive leakage from the paddy field. The measured parameters included GHG emissions, soil water content, redox potential, soil temperature, soil swelling, total carbon, total nitrogen, iron, and manganese. The results showed that the soil column with macropores and drainage had significantly lower CO2 and CH4 emissions than that without macropores and drainage. In addition, the soil level increment, and thus, the amount of gas (CH4) produced in the soil column with drainage were lower than that without drainage. The combination of drainage treatment and macropores might have effectively acted as a hydrodynamic gradient and a structure that promotes freshwater intrusion into deeper soil profiles, inhibiting absolute anaerobic methanogenic activity. The redox potential of the column with drainage and macropores was the highest. Moreover, CO2 and CH4 emissions were reduced at a relatively small drainage rate of 6.5 mm d − 1 by adding macropores to the soil. The findings confirmed that GHG emissions were effectively reduced by a porous soil structure at a low drainage rate. Macropore application also exhibited effectiveness at mitigating nutrient loss (TOC and TN) through the drainage. Therefore, low tillage before flooding would be preferable to conserve the macroporous structure. However, the results also highlight an adverse effect on mineral leaching (particularly Mn) through the column with macropores.

Analysis of the Pile-Soil Combined Effect of Micropiles in Strengthening Expansive Soil Landslide in Southern Shaanxi Based on the Dynamic Soil Arch Model

Southern Shaanxi region is mountainous and landslide disasters are frequent. Micropile reinforcement technology is widely used in landslide management, especially in landslide emergency rescue projects, due to easy construction, small soil disturbance, and strong site adaptability. Soil arch effect is an important prerequisite for safe and economic performance of the support function of micropile. For the swelling soil landslide of the accumulation layer in southern Shaanxi, firstly, a numerical model is established by means of thermal-mechanical coupling of FLAC3D to explore the variation of the soil arch form with different swelling forces. Then, two theoretical models are proposed under normal working condition and rainfall working condition. The evolution and failure mode of soil arch are analyzed. The results show that the soil expansion after rainfall causes the change of the soil arch mode, the range of pile-soil interaction is obviously reduced, and the soil arch effect is weakened. It should be considered in the design of micropiles in strengthening expansive soil landslide.

Treatment of Swelling Soil Using Crushed Glass Wastes and Lime

Treatment of Swelling Soil Using Crushed Glass Wastes and Lime