Soil Problems Research Articles

Compressibility Characteristics of an Organic Soil Treated with Fly Ash and Fly Ash-Based Geopolymer

Organic soils are problematic soil for various engineering applications due to their high compressibility and low shear strength which need to be improved. For many soil improvement techniques, using waste materials, such as fly ash (FA), is a practical and sustainable process. In this research, FA and geopolymer were used e used to reduce organic soil's compressibility. A one-dimensional consolidation test was performed to evaluate the organic soil's consolidation and compressibility properties. The geopolymer was prepared using 20% FA and of sodium hydroxide ratio and sodium silicate alkali solutions. The geopolymer specimens were first cured for 2 hours at 45 and 65 oC, then cured for further 28 days at room temperature. The consolidation test results showed that FA-based geopolymer is effective in stabilizing organic soils due to the observed improvement in the compressibility, consolidation, and permeability characteristics. The compression index decreased by 98.16%, and the permeability decreased by 95%.

Microstructural Characterization of Fibric Peat Stabilized with Portland Cement and Silica Fume.

Peat is a renowned problematic soil and needs stabilization to enhance its engineering properties. Silica fume (SF) and Ordinary Portland Cement (OPC) were extensively adopted to increase the mechanical properties of peat; however, their microstructural analysis is lacking. Investigated herein is the microstructural evolution caused by the OPC and SF implementation in peat soil stabilization. Initially, the compositional analysis (elements and oxides) of peat and binders was carried out via energy-dispersive X-ray (EDX) and X-ray fluorescence (XRF). Subsequently, the microstructural changes that occurred in the stabilized peat were examined through a series of microstructural analyses. The analysis includes scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and thermogravimetric analysis (TGA) for morphological, mineralogical, functional group analysis, and bond thermal analysis, respectively. The SEM micrographs evidence the transformation of loosely packed with large micropores of untreated peat into a compact dense peat matrix. This transformation is due to the formation of newly developed minerals, i.e., calcium hydrates (CH), calcium silicate hydrates (C-S-H), calcium aluminate hydrate (CAH), ettringite (Aft) caused by the pozzolanic reaction of binders as recorded by the XRD. Similarly, different molecular functional groups were found in the FTIR analysis with the incorporation of SF and OPC. Finally, the percentage of mass loss was assessed through TGA analysis revealing the decomposition of stabilized in the second and third stages.

Evaluating the Effect of Nano-SiO2 on Different Types of Soils: A Multi-Scale Study

A rapid growth in the population leads to a large increase in engineering construction. This means there is an inevitability in regard to building on problematic soils. Soil reinforcement becomes an important subject due to the fact that it is a concern for engineers and scientists. With the development of nanotechnology, more and more nanomaterials are being introduced within the practice of soil reinforcement engineering. In this study, the reinforcing effect of novel nanomaterial nano-silica (SiO2) applied to different kinds of soils was systematically studied. The nano-SiO2-reinforced soil possessed lower final water evaporation loss, and evaporation rates. The nano-SiO2 increased the shear strength of clayey soil and sandy soil under both cured and uncured conditions, but the reinforcing effect on clayey soil was more obvious. The addition of nano-SiO2 promotes the friction angle and cohesion of clayey soil; further, it also increases the cohesion of sandy soil. The unconfined compressive strength of clayey soil was enhanced by nano-SiO2, meanwhile, the nano-SiO2-reinforced soil possessed greater brittleness. The microstructure of nano-SiO2-reinforced soil is shown via SEM analysis, and the results of X-ray diffraction (XRD) tests show that there are no new mineral components generated during the reinforcing process. It was also found that nano-SiO2 possessed little influence on the soil pH value. Adding nano-SiO2 will not damage the original chemical environment of the soil. The microstructure of nano-SiO2-reinforced soil was observed to prove the results above. In general, nano-SiO2 is an excellent soil additive that can improve the mechanical properties of both clayey soil and sandy soil effectively. This research provides more ideas and directions for the purposes of selecting soil reinforcement materials.

Engineering behavior of cement-treated stiff clay subjected to freezing/thawing cycles

Deep soil mixing (DSM) with cement has been adopted to enhance soft ground and stabilize problematic soils worldwide. The literature is limited to DSM-treated soft soils with low cement contents, temperate curing conditions, short-term stability, and compressive properties. Due to the increased applications of DSM in cold regions, the study on the mechanical behavior of cemented soils (soilcrete) with high cement content under freezing/thawing (F/T) conditions has become important. In the present study, cylindrical specimens formed by mixing Edmonton stiff clay with high ordinary Portland cement contents (over 20%) were prepared in the lab to examine the mechanical behavior of soilcrete under unexposed and F/T exposed conditions. Unconfined compression and tensile tests were performed to assess changes in the mechanical properties of specimens cured for 1 to 300 days after 1 to 20 F/T cycles at freezing temperatures from −2 to −20 °C. Test results showed that the compressive and tensile strength of soilcrete increased with curing age and decreased significantly with more F/T cycles. Additionally, the mechanical strength loss in the −5 to −10 °C range was more significant than in the −2 to −5 °C range, indicating that the lower temperature caused more severe damage to the samples. Although the mass loss was <5% for most samples, it increased with more F/T cycles and the declining temperature, indicating that the mass loss was able to reflect the impact of F/T cycles.

Post-cyclic Loading Relationship Effects to the Shear Stress and Cyclic Shear Strain of Peat Soil

Peats originate from plants and denote the various stages in the humification process. This condition renders the peat extremely soft and can be considered problematic soil. Thus, this study is conducted to examine and comprehend the particularities of peat engineering behaviour in respect to the relationship effects to the shear stress and cyclic shear strain of peat soil various characteristics to establish suitable correlation. This study carried out by using triaxial testing described by geotechnical test standards BS-1377: Part 8: 1990. Methods of Testing Soils for Civil Engineering Purposes: Shear Strength Tests (Effective Stress) that required for consolidated undrained and consist of five main stages: saturation, consolidation, static, dynamic, and post-cyclic loading using the GDS Enterprise Level Dynamic Triaxial Testing System (ELDYN). The parameters of shear strength were obtained in the peak deviator stress at a maximum of 20% of axial strain by using an undisturbed sample with an effective pressure imposed of 25, 50, and 100 kPa. In this study, all specimens are subjected to cyclic loading up to 100 cycles based on a one-way loading system with strain-controlled conditions. Based on the analysis conveyed, the post-cyclic shear stress decreased compared to its initial value of about 65.56 kPa (PNpt-100 kPa) in static and decreased to 14.9616 kPa in post-cyclic (PNpt-25 kPa-1 Hz). The principal stress ratio (σ'1/σ'3) shows the maximum values of this ratio that are located in the narrow zone of 1.61 to 1.12. Doi: 10.28991/CEJ-2022-08-12-08 Full Text: PDF

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.

Peat Stabilization Using Waste Crumb Rubber Tire

Peat is a notoriously problematic soil having high-water content, a large void ratio, and weak engineering properties. Thus, it needs to be treated before utilization to withstand structural stress. On the other hand, the amount of waste tires increases exponentially due to the high demand for vehicles. Therefore, they need to be sustainably recovered and recycled rather than disposed or incinerated. This study aimed to stabilize the peat collected from Sungai Bidut, Sibu with crumb waste tires (CRT). Different percentages (15%, 20%, and 25%) of CRT were used to determine its effect on peat strength improvement. The effectiveness of CRT was assessed using mechanical testing i.e., unconfined compressive strength (UCS). The optimum amount of CRT was also concluded based on the UCS by comparing it with the untreated peat. Finally, the morphological change of peat in depth was studied by scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The results revealed that the optimum compressive strength of the peat soil is achieved with the incorporation of 15% CRT. The highest UCS of 99.73 kPa was recorded with the use of 15% CRT and the strength decreases with the increasing use of CRT. The microstructural tests show that peat becomes more compact and humified with depth. Moreover, peat at any depth is mainly composed of carbon (C) and oxygen (O) and the small proportion of Silicon (Si) indicates less amount of clay particles.

Stabilization of Black Cotton Soil Using RBI Grade 81 and Sodium Silicate

Abstract: Nearly 51.8 million hectares of land area in India is covered with expansive soils (mainly Black Cotton soil). The property of the expansive soils, in general, is that they are very hard when in dry state, but they lose all of their strength when in wet state. In light of this property of expansive soils, these soils pose problems worldwide that serve as challenge to overcome for the Geotechnical Engineers. One of the most important aspects for construction purpose issoil stabilization, which is used widely in foundation and road pavement constructions; this is because such a stabilization regime improves engineering properties of the soil, such as volume stability, strength and durability. In this process, removal or replacing of the problematic soil is done; replacement is done by a better quality material, or the soil is treatedwith additives. In the present study, RBI Grade 81 obtained from Alchemist Touchnology Limited, Gurgaon, Haryana and Sodium Silicate solution 5mol/Liter obtained from Organ Refractories, Khammam, Telangana are used for the stabilization of black cotton soil. These additives are added in various proportions

Review of the Effects of Freezing/Thawing Cycles on the Engineering Properties of Soilcrete

Soil mixing, which blends the natural soils with cementitious materials (or binders), has been used to enhance the soft ground and improve problematic soils for several decades. With developments in technique and machinery, the embedded depth of soil mixing has increased from the shallow ground to as deep as tens of meters, especially when deep soil mixing and grouting emerged in the 1970s. Extensive studies have been undertaken on the physical and mechanical properties of the mixing products (soilcrete) with regard to water content, soil type, binder type, binder content, curing age, and curing condition. However, most studies initially focused on soil mixing in temperate weather. In recent decades, soil mixing in cold regions has become common. Thus, plenty of research has been conducted on the engineering properties of soilcrete exposed to weathering conditions in cold regions, namely freezing/thawing (F/T) cycles. However, while summaries of studies on soilcrete used in temperate conditions have been undertaken by researchers, reviews of studies on soil mixing in cold regions are still rare. In order to link potential research on soil mixing with previous studies and point out the possible research directions, a review of works on soilcrete subjected to F/T cycles was composed. The present paper summarizes the testing methods adopted by various studies and the change in engineering properties of soilcrete caused by F/T cycles.

Effect of Tree Leaf Litterfall on available Nutrients and Organic Carbon Pools of Soil

A study was conducted to investigate the effect of leaf litterfall of shelterbelt, Azadirachta indica, Ailanthus excels and Prosopis cineraria and control (devoid of trees) on available nutrients and organic carbon pools of soil from 3 distances (2, 5 and 10m) The total litterfall during the study period ranged between 1712 and 4126kg/ha and it was found maximum in the month of January and it was minimum in February in different plantations. Annual litterfall showed considerable variation among different plantations. Litter accumulation under the different plantations canopy was highest in the shelterbelt followed by Prosopis cineraria and lowest in the Azadirachta indica. There was improvement in soil organic carbon, dissolved organic carbon, microbial biomass carbon, available macro (N, P and K) and micronutrients (Zn, Fe, Mn and Cu) tree species when compared to field without trees. Significant improvement in soil organic carbon (0.14 to 0.26 %), available N (55.9 to 116.6kg/ha) P (9.6 to 13.6kg/ha) and K (188.9 to 248.3kg/ha) was observed under these tree species compared to field without trees. The content of Zn, Cu, Fe and Mn and was 15, 25, 40 and 51 percent, respectively higher under these tree species than the control field. The amount of nutrients returned to the soils through litter was significantly highest at 2m distance under different plantations. The present study indicated that these available nutrients and organic carbon pools improved significantly across the different land use system. Due to intensive cultivation and monocropping, the fertility of soil is deteriorating day by day. Simultaneously it is creating a pressure on the natural resources like soil because the population is increasing day by day. Therefore, it is wise to use degraded and problematic soil for cultivation. Agroforestry systems have been recognized as an alternative for the rehabilitation of degraded areas and it provides ecosystem services and reduces human impacts on natural forests (Nair et al., 2009). Tree based land use systems have special role in reclamation of wastelands, use of poor-quality waters, organic carbon build up and moderating climate change related risks. In areas of Haryana and Rajasthan trees like Prosopis cineraria, Azadirachta indica and Ailanthus excels are more beneficial under adverse environments due to their drought hardiness, resistance to inhospitable climate and assured economic returns. These tree species can be grown on soils having poor fertility, moisture deficit and high soil temperature.

Novel application of Google earth engine interpolation algorithm for the development of geotechnical soil maps: a case study of mega-district

This article explores the novel application of the Google Earth Engine (GEE) platform using the inverse distance weighting (IDW) interpolation technique based on an improved version of the modified Shephard method for the development of specialized geotechnical soil maps (GSMs) for mega-district Lahore. The study area was assessed at multiple depths in terms of key geotechnical properties. The result depicts a predominance of fine-grained soil at a shallow depth of 3 m exhibiting low to moderate soil stiffness, consistency and activity along with a few zones of problematic soil with adverse geotechnical characteristics which require due attention. Whereas beyond 3 m the study area exhibits higher bearing values, low plasticity and non-active soil. Besides, the chemical content level was within permissible limits except for a few spots. The comprehensive statistical evaluation based on key performance indices indicates the efficient performance of the novel GEE-based IDW algorithm to yield significantly accurate maps.

Mechanical Strength of Saline Sandy Soils Stabilized with Alkali-Activated Cements

Saline soils usually cannot satisfy the requirements of engineering projects because of their inappropriate geotechnical properties. For this reason, they have always been known as one of the problematic soils worldwide. Moreover, the lack of access to normal water has intensified the use of saline water resources such as seawater in many construction and mining projects. Although cement stabilization is frequently used to improve the engineering properties of saline soils, Portland cement’s usage as a binder is constrained by its negative consequences, particularly on the environment. In this line, the effects of NaCl on the microstructural and mechanical properties of alkali-activated volcanic ash/slag-stabilized sandy soil were investigated in this study. Moreover, the effects of binder type, slag replacement, curing time, curing condition, and NaCl content on the mechanical strength of stabilized soils were examined. In addition, microstructural analyses, including XRD, FTIR, and SEM–EDS mapping tests, were performed to understand the physical and chemical interaction of chloride ions and alkali-activated cements. The results show that alkali-activated slag can be a sustainable alternative to Portland cement for soil stabilization projects in saline environments. The increase in sodium chloride (NaCl) content up to 1 wt.% caused the strength development up to 244% in specimens with 50 and 100 wt.% slag, and adding more NaCl had no significant effect on the strength in all curing conditions. Microstructural investigations showed that the replacement of volcanic ash with slag resulted in the formation of C-S-H and C-A-S-H gels that reduced the porosity of the samples and increased mechanical strength. Furthermore, surface adsorption and chemical encapsulation mechanisms co-occurred in stabilized soil samples containing slag and volcanic ash.

Investigation of Mechanical Properties of Quicksand Stabilized with Bitumen Emulsion and Reinforced with Waste Polypropylene Fibers and The Effect of Freeze and Thaw on Its Performance

The existing quicksands in the desert are among the problematic soils whose stabilization has been considered by experts. Emulsion bitumen is one of the environmentally friendly stabilizers of these sands. Also, the method of reinforcement with (fibers) has many advantages due to the increase in soilstrength in the same way and the formation of thickness in the soil mass. The aim of this study was to investigate the effect of polypropylene fibers and emulsion bitumen on improving sandy soil properties and the effect of freeze-thaw cycles on the behavior of soils stabilized by these two substances; For this purpose, samples of aeolian sand soil with 0%, 0.25%, 0.5%, 0.75% and 1% waste polypropylene fibers of 0, 5, 10, 15% bitumen emulsion were made and tested for California load-bearing capacity and uniaxial compressive strength. Also, to evaluate the effect of freeze-thaw cycle, the samples were subjected to uniaxial resistance test after enduring 3 and 7 freeze-thaw cycle. The results show that the addition of fibers and bitumen to the sand first increases the specific gravity and CBR and decreases from one percent onwards by increasing the fibers of these two parameters; It has compressive strength and ultimate strain with increasing fiber percentage; In general, increasing the percentage of fibers from 0to 1% on average increases the compressive strength by 91% and the final strain by 54% and increasing the percentage of bitumen from 5 to 15% on average increases the compressive strength by 4% and the final strain by 13%. In addition, the results show that the compressive strength of the samples decreases by an average of 15% and 19% after withstanding 3 and 7 freeze-thaw cycle, respectively; However, after enduring 3 and 7 freeze-thaw cycle, the compressive strength increases with increasing the percentage of fibers to 75%.

A Comparative Study for the Effect of Some Petroleum Products on the Engineering Properties of Gypseous Soils

Gypseous soils are considered problematic soils because the soil cavities happen during receiving the water or this type of soil and solving gypsum materials and contract in a soil volume. In this study, three types of gypseous soils are used; soil1, soil2, and soil3 with gypsum content (28.71%, 43.6%, and 54.88%) respectively, petroleum products (engine oil, fuel oil, and kerosene) are added to the soils with percentages (3%, 6%, 9%, and 12%) for each product. The result showed that specific gravity, liquid limit, optimum moisture content (O.M.C), and maximum dry density decreased with an increased percentage of product for all types of products. The direct shear (dry and soaked case) results show that increasing the (angle of internal friction and the soil cohesion) for soil1, soil2, and soil3 by adding engine oil and fuel oil. Still, when the soils were treated with kerosene, the angle of internal friction increased while cohesion decreased. The collapse potential for the treated soils increases with increasing gypsum content for all petroleum products. The collapse potential (CP) for (soil1) decreased by 47% when using 6% of the engine oil, 48.8% when using 9% of the fuel oil, and 55% when using 9% of the kerosene. The same percentage of the petroleum products (engine oil, fuel oil, and kerosene) decrease the collapse potential for (soil2), (47%, 46%, and 50%) respectively and decrease the collapse potential for (soil 3), (51%, 47.7%, and 52%) respectively. In the unconfined compressive test applied on (soil1) using maximum density, the results show that the soil strength increased (26% and 10%) when using 6% and engine oil and fuel oil, respectively, while the soil strength decreased by 29% when treated with 9% of kerosene.

Effect of silica fume on the undrained strength parameters of dispersive

Dispersive soils are one of the problematic soils such as swelling and collapsible soils and they are common in many countries of the world. Due to dispersive soils, significant problems arise in road embankments and earth dams. Therefore, the use of such soils is possible with treatment. Silica fume (SF) as a waste material has been used in concrete production instead of partially cement, in the stabilization of expansive soils and in many civil engineering applications for different purposes. Within the scope of this study, to determine the dispersibility behavior of the soil sample, crumb test was performed. SF additive was used to improve the soil sample, which was determined to have high dispersibility. The compaction properties of the soil specimens mixed with SF in different proportions (0, 5, 10, 15, 20, 25 and 30%) were determined by the standard Proctor test. Crumb tests were performed to assess the dispersibility potential of the prepared specimens, and also unconsolidated and undrained (UU) triaxial tests were carried out to evaluate the strength parameters. UU experiments were performed under 20 kPa, 40 kPa and 60 kPa effective cell pressures on specimens cured for 1, 7 and 28 days because stabilization occurred at shallow depths in field applications. As a result, it was determined that the dispersibility feature of the soil sample was treated and the strength properties were improved depending on the SF content.

Modeling Undrained Shear Strength of Sensitive Alluvial Soft Clay Using Machine Learning Approach

Soft soils are commonly located in many regions near seas, oceans, and rivers all over the world. These regions are vital and attractive for population and governments development. Soft soil is classified as problematic soil owing to sustaining low shear strength and high settlement under structures. Constructing structures and/or infrastructures on soft soil is a considerable risk that needs great attention from structural engineers. The bearing capacity of structure foundations on soft soil depends mainly on their undrained shear strength. This soil feature strongly influences the selection of appropriate soil improvement methods. However, determining undrained shear strength is very difficult, costly, and time-consuming, especially for sensitive clay. Consequently, extracting undisturbed samples of sensitive clay faces several difficulties on construction sites. In this research, accurate field-tested data were fed to advanced machine learning models to predict the undrained shear strength of the sensitive clay to save hard effort, time, repeated laboratory testing, and costs. In this context, a dataset of 111 geotechnical testing points were collected based on laboratory and field examinations of the soil’s key features. These features included the water content, liquid limit, dry unit weight, plasticity index, consistency index, void ratio, specific gravity, and pocket penetration shear. Several machine learning algorithms were adopted to provide the soft clay modeling, including the linear, Gaussian process regression, ensemble and regression trees, and the support vector regression. The coefficient of determination was mainly used to assess the performance of each predictive model. The achieved results revealed that the support vector regression model attained the most accurate prediction for soil undrained shear strength. These outcomes lay the groundwork for evaluating soil shear strength characteristics in a practical, fast, and low-cost way.

A Study of Cost Comparison of Flexible Pavement Using Different Soils

India is home to the world’s second-largest road network. It has a diverse range of soil types, each with its own set of conditions and characteristics, on which the road network is built. IRC: 37-2018 was used for the Design and Cost Analysis of Flexible Pavement for five distinct types of soils: Black cotton soil, Alluvial soil, Sandy soil, Red Laterite soil, and Murram soil. The Resilient modulus which depends on CBR value of the soil has been found to influence the pavement thickness, strength and performance. The project’s cost is determined by the pavement thickness, which again is determined by the soil’s CBR value. By employing a soil with a high CBR value, the project’s pavement thickness and cost will be decreased. On poor or problematic soils, soil stabilisation techniques should be employed to improve CBR value and save project expenses. According to the findings, employing the CBR value improves the pavement’s strength and hence saves time when planning a pavement.

Analysis of Chemical Stabilizer on the Behavior of Expansive Soil

Abstract: Rapid growth in industrialization and urbanization in developing countries like India, leads to increasing scarcity of land which forces us to utilize the available land even though it is problematic. Problematic soils are those having low bearing capacity, high compressibility and high swelling/shrinkage and as such they are not suitable for any geotechnical application. In most geotechnical engineering projects, increase in concentration of Red mud, Maximum dry density of mixture increases. The mix containing 30% Red Mud + 67% Soil + 3% Fly Ash has good bearing strength characteristics. The bearing strengths of Red Mud were increased to 7.354% on addition of Red Mud and Fly Ash in the ratios of 30% and 3% respectively. With increase in concentration of red mud, California bearing ratio increase up to a fixed concentration of Red mud. With increase in percentage concentration of Red Mud, Optimum moisture content of the mixture (Red Mud + Fly Ash + Soil) increases. With increase in concentration of Red mud, Maximum dry density of mixture increases.

Prediction of Post-Construction Settlement of Road Embankment on Soft Soil Deposits

Organic soils are often considered problematic soils around the world due to several reasons. Excessive settlement is one of the main concerns when constructing infrastructure on soft grounds with organic soil deposits. Ground improvement is mainly carried out on the sub surfaces that lack the strength and stability to bear the structure to be constructed and undergo large settlement during operation. Different soft-ground treatment methods must be applied based on the soil properties to reduce the expected settlements during construction and operation periods. In this context, it is essential to know the behaviour of the subsurface after the ground improvement process. This study mainly investigates the accuracy of the settlement prediction methods during the post-construction stage of the Colombo-Katunayake Expressway Project in Sri Lanka. Settlement prediction was done for the Defect Liability Period using the hyperbolic method, the Mesri method and the Ladd method. A comparison of the predicted settlement with the measured field settlement was done to assess the accuracy of the settlement prediction methods. The comparison showed that the hyperbolic method was more accurate and convenient for predicting the settlement of the embankment. KEYWORDS: Soft ground treatment methods; Preloading; consolidation settlement; Asaoka method; hyperbolic method

Small to medium strain dynamic properties of Lanzhou loess, China

Loess is a kind of world-recognized problematic soil and, as a consequence, it is a major hazard in geotechnical engineering. This study examines the small to medium strain dynamic properties of Lanzhou intact and recompacted loess through a set of resonant column (RC) tests. The influence of soil structure on the small-strain shear modulus G0, the variations of G/G0, and damping ratio DT(%) with shear strain γ were analyzed and discussed. The test results show that the structure has an important influence on the dynamic properties of dry loess at small and medium strain, whereas, with the increase of moisture, its effect weakens. It is proved that a normalized correlation between G/G0 and γ/γ0.7 is practically identical for undisturbed and recompacted loess in Lanzhou, irrespective of soil structure, which may be useful in practical applications.