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1

Study on the dynamic development law of fissure in expansive soil under different soil thickness

Guo Jianhua, Ding Gang, Wang Hanhui, Li Shichang, Dai Zhangjun

Archives of Civil Engineering

|

2023

|

Vol. 69, nr 4

519--534

EN

Fissures are an important factor to induce slope instability of expansive soil channel, which destroys the integrity of soil mass and deteriorates soil mass. Currently, the research is limited to the fissures in the plane direction, and it is very important to reveal the development mechanism of fissures in expansive soils along the depth direction by studying the development law of fissures in expansive soils with different thicknesses. In this study, taking expansive soil on channel slope of the Middle Route Project of South-to-North Water Transfer as an example, crack expansion tests with thickness of 10 mm, 20 mm, 30 mm and 40 mm are carried out based on self-designed crack expansion test device. An innovative test method for volumetric fracturing rate is proposed and the following conclusions are drawn: (1) the later the cracking time of soil body is, the lower the water content of cracking and the higher the water content after stabilization when the soil body is thicker; (2) When the fissures develop in soils of different thicknesses, their plane fissure rate changes with time in accordance with the logistic law; (3) Volumetric fracturing increases significantly with thickness; (4) The development of fissures is the form of stress release of soil mass, and the release along depth direction is the main form for soil mass with large thickness. (5) It is of great significance to study the law of fracture development in depth direction for further exploring the mechanism of fracture propagation.

2

Application of steel slag in stabilizations of expansive soil: an experimental study

Kabeta Worku Firomsa

Archives of Civil Engineering

|

2023

|

Vol. 69, nr 1

105--117

EN

This study was carried out to evaluate the effect of steel slag (SS) as a by-product as an additive on the geotechnical properties of expansive soil. A series of laboratory tests were conducted on natural and stabilized soils. Steel slag (SS) was added at a rate of 0, 5, 10, 15, 20, and 25% to the soil. The conducted tests are consistency limits, specific gravity, grain size analysis, modified Proctor compaction, free swell, unconfined compression strength, and California Bearing Ratio. The Atterberg limit test result shows that the liquid limit decreases from 90.8 to 65.2%, the plastic limit decreases from 60.3 to 42.5%, and the plasticity index decreases from 30.5 to 22.7% as the steel slag of 25% was added to expansive soil. With 25% steel slag content, specific gravity increases from 2.67 to 3.05. The free swell value decreased from 104.6 to 58.2%. From the Standard Proctor compaction test, maximum dry density increases from 1.504 to 1.69 g/cm3 and optimum moisture content decreases from 19.77 to 12.01 %. Unconfined compressive strength tests reveal that the addition of steel slag of 25% to expansive soil increases the unconfined compressive strength of the soil from 94.3 to 260.6 kPa. The California Bearing Ratio test also shows that the addition of steel slag by 25% increases the California Bearing ratio value from 3.64 to 6.82%. Hence, steel slag was found to be successfully improving the geotechnical properties of expansive soil.

3

Utilization of coconut shell residual in green roof: hydraulic and thermal properties of expansive soil amended with biochar and fbre including theoretical model

Wang Hao, Garg Ankit, Zhang Xiaoyong, Xiao Yangyang, Mei Guoxiong

Acta Geophysica

|

2020

|

Vol. 68, no. 6

1803--1819

EN

The study intends to explore hydraulic and thermal properties of expansive soils treated with fbre, biochar and biochar–fbre mix. Both fbre and biochar are derived from coconut shell, which is highly common in coastal regions around the world. Besides, benefts, limitations and engineering feasibility of these geomaterials in green roofs are explored. Theoretical framework for thermal–hydraulic analysis is proposed based on mass conservation and the frst law of thermodynamics. Heat capacity, thermal conductivity, water retention curve, crack intensity factor (CIF) and saturated and unsaturated hydraulic conductivities of four kinds of soils are evaluated and compared. Characterizations of geomaterials are also investigated via thermal mass loss, micro-structure, surface area and functional groups identifcation. Both biochar and fbre admixtures contribute to improvement in soil heat capacity and saturated and unsaturated hydraulic conductivities. Biochar enhances saturated and residual water contents of expansive soil by 10% and 8%, respectively. Also, biochar decreases soil thermal conductivity and CIF by 31% and 5%, respectively, while fbre decreases soil-saturated and residual water contents by 15% and 29%, respectively, and reduces soil thermal conductivity and CIF by 21% and 50%, respectively. Soil–biochar–fbre composite is also recommended due to low air-entry value, acceptable water-holding capacity and limited crack propagation. The study flls the knowledge gap of how soil thermal–hydraulic properties are afected due to biochar and/or fbre admixture. It is recommended to pay more attention on production and utilization of biochar derived from coconut shell currently utilized for fbre extraction.

4

A comparative laboratory investigation into the role of geosynthetics in the initial swell control of an expansive soil

James Jijo, Vijayasimhan Sivapriva, Srinivasan Hemavathi, Arulselvan Javasri, Purushothaman Sathya, Paramasivam Murali

Civil and Environmental Engineering Reports

|

2019

|

Vol. 29, no. 4

18--40

EN

Volume change in expansive soils due to the intervention of water causes swell. A laboratory investigation using two different geosynthetic materials was designed to minimise the swell characteristics. The influence of three parameters, being geosynthetic material [Secutex (ST) and Combigrid (CG)], orientation (horizontal and vertical), and number of layers (1, 2, and 3) on the swell of an expansive soil was studied to better understand the potential for geosynthetics in swell control. The study on the immediate swell characteristics (limited to 24 hours) helps in gaining confidence in the use of geosynthetics in the swell control of expansive soils. From the investigation results, it was found that all three parameters, being type of material, orientation, and number of layers influenced the swell control of the soil. When two layers of ST and CG were placed both vertically and crossed, they reduced the swell of the virgin soil by almost 60% and 44%, respectively. It can, therefore, be concluded that geosynthetics can play an effective role in the swell control of expansive soils.

5

Współpraca ściany oporowej wykopu z podłożem gruntowym o właściwościach ekspansywnych

Kuchler A.

Inżynieria i Budownictwo

|

2018

|

R. 74, nr 6

313--315

PL

Rozpatrzono ścianę oporową opisaną modelem liniowo-sprężystym, za którą zalega na całej wysokości aktywna strefa gruntu o właściwościach ekspansywnych. Do opisu tej strefy zastosowano dwuparametrowy model liniowo-sprężysty. Podano równanie różniczkowe oporowej ściany wspornikowej, rozwiązanie ogólne tego równania, a następnie przykład rozwiązania wspornikowej ściany oporowej współpracującej z dwoma rodzajami aktywnej strefy gruntu ekspansywnego. Wyniki obliczeń porównano z rozwiązaniem ściany obciążonej parciem gruntu.

EN

Considered retaining wall described linear elastic model, for which default the entire height of the active area of land with expansive properties. For the description of the zone was used a two-parameter model linear-elastic. Given differential equation of the cantilever retaining wall, the general solution of this equation and then solve such a cantilever retaining wall cooperating with the two types of active zone of expansive soil. The calculation results are compared with the solution of the wall-loaded ground pressure.

6

Klasyfikacja przemieszczeń pionowych obiektów budowlanych z wykorzystaniem sieci neuronowej SVM

Mrówczyńska M.

Materiały Budowlane

|

2016

|

nr 11

44--45

PL

W artykule przedstawiono podstawowe zasady budowania i uczenia sieci neuronowych zwane metodą (techniką) wektorów podtrzymujących (ang. Support Vector Machine – SVM) wraz z możliwością aplikacji tego rodzaju sieci. Sieci nieliniowe SVM wykorzystano do klasyfikacji danych separowalnych liniowo w celu sformułowania modelu przemieszczeń punktów sieci pomiarowo-kontrolnej. Punkty sieci pomiarowo-kontrolnej zostały założone na obiekcie budowlanym posadowionym na gruntach ekspansywnych.

EN

The article presents the basic rules for constructing and training neural networks called the Support Vector Machine (SVM) method as well as possible applications for this kind of network. Non-linear SVM networks have been used for classifying linearly separable data with a view to formulating a model of displacements of points in a measurement-control network. The points of the measurement-control network were placed on a civil engineering object located on expansive soil.

7

Wpływ metody badania na wyznaczone ciśnienie pęcznienia na przykładzie iłów krakowieckich

Wdowska M., Lendo-Siwicka M., Garbulewski K., Michalczuk K.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

|

2016

|

z. 63, nr 1/II

121--128

PL

Projektowanie obiektów budowlanych posadowionych w iłach stanowi trudne zadanie inżynierskie ze względu na możliwość zwiększenia (pęcznienie) lub zmniejszenia (skurcz) ich objętości [8] pod wpływem zmian wilgotności naturalnej, dlatego też obiekty posadowione na iłach często ulegają awariom. Nietypowy charakter zachowania się iłów wynika przede wszystkim z obecności minerałów hydrofitowych (m.in. montmorylonit, beidelit i inne). Na etapie projektowania i wymiarowania budowli posadowionej w iłach podstawowym parametrem jaki należy wziąć pod uwagę jest ciśnienie pęcznienia, które wyznacza się w badaniach laboratoryjnych stosując metody różniące się warunkami badań prezentowanymi w dalszej części artykułu. Jak wykazały dotychczasowe analizy, wybór metody określania ciśnienia pęcznienia ma kluczowe znaczenie w określaniu wiarygodnych wartości tego parametru. W artykule zaprezentowano wyniki badań ciśnienia pęcznienia mioceńskich iłów krakowieckich występujących w zapadlisku przedkarpackim przy zastosowaniu trzech najczęściej stosowanych metod badawczych. Na podstawie prezentowanych w artykule wyników badań stwierdzono, że ciśnienie pęcznienia badanych iłów zmieniają się w szerokim zakresie wartości (od 11,6 kPa do 270 kPa) zależnie od wskaźnika plastyczności IP i metody badań.

EN

In the geotechnical design of structures in expansive clays the additional actions occurring during volume changes, especially during swelling, should be taken into account for design appropriate safeguards which is usually difficult task for engineers. The most important action that must be taken into account in the design of structures in clays and directly applicate in dimensioning structures is swelling pressure, which is determined in the laboratory using methods with different test conditions. The previous tests results show that the choice of method for determining the swelling pressure is a key problem in determining reliable values of swelling pressure. This paper presents the results of laboratory tests carried out to determine the swelling pressure of Miocene clays occurring in Carpathian Fore-Deep using the following three methods: free swelling in accordance with ASTM 4546, a series of sampling as well as methods of constant volume in accordance with PN-88 / B- 0448. The clay samples tested are characterized by clay fraction in the range of 32 to 60%, values of liquid limit in the range of 72.2 ÷ 139.6% and the plastic index Ip from 45.8% to 112 %. Clays tested are of high colloidal activity soils expressed by the ratio of plasticity index to the content of clay fraction (A ratio acc. to Skempton) in the range of 1.1 ÷ 1.9, which justifies their classification to clays with high potential swelling. Based on the research presented in the paper it was found that the swelling pressures of clays are in the broad range of from 11.6 kPa to 270 kPa, depending on the plasticity index Ip and test method. The highest swelling pressure values obtained using the method of free clay swelling, the smallest from the method of the zero volumetric strain.

8

Długookresowy monitoring obiektów posadowionych na podłożu ekspansywnym

Gadomska M.

Materiały Budowlane

|

2015

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nr 5

57--58

PL

Obiekty posadowione na podłożu ekspansywnym ulegają licznym uszkodzenion i wymagają długookresowych obserwacji. Na podstawie wieloletnich obserwacji stwierdzono istotne przemieszczenia pionowe, pomimo przeprowadzonych prac zabezpieczających. W przypadku niektórych obiektów przemieszczenia są zróżnicowane i w związku z tym można zrezygnować z częstych obserwacji części obiektu o nieznaczących przemieszczeniach.

EN

Objects constructed in expansive soil foundation reveal significant damage and require long-term observation. In effect of long-term monitoring, significant vertical displacements that had occurred despite conservation works, were found on the objects. On some objects the displacements are highly diversified and, therefore, observation of the parts with slight displacements can be abandoned.

9

Evaluation of expansivity of Neogene clays and glacial tills from central Poland on the basis of suction tests

Izdebska-Mucha D., Wójcik E.

Geological Quarterly

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2015

|

Vol. 59, No. 3

593--602

EN

This paper presents the characteristics of the expansivity and quantitative prediction of heave of clay soils from Poland based on suction testing. 11 Neogene clays and 6 glacial tills, differing in genesis and plasticity, were analyzed to identify the expansive potential using eight empirical methods. The laboratory studies included measurements of soil-water characteristic curves and soil index properties. Data from water content, volume and suction measurements served to determine the suction compression index Ch and the suction-water content index Dh/Dw of the soils examined. The values of these indices are clearly dependent of the clay fraction content in tested soils. Compared with glacial tills, Neogene clays are expected to exhibit larger changes in volume due to changes in soil suction. Comparative results of the evaluation of expansivity suggest that the chosen classification methodologies provided consistent expansion ratings for glacial tills, while values for Neogene clays vary from low to very high. The lowest expansivity classes have been obtained from evaluation based on soil suction. The McKeen (1992) method has been adopted for calculations of the potential field heave of Neogene clays and glacial tills. In order to provide a rational estimation of expansive soil behavior, specialists should take into consideration the specific site and design features.

10

Expansivity of Neogene clays and glacial tills from Central Poland

Izdebska-Mucha D., Wójcik E.

Geological Quarterly

|

2014

|

Vol. 58, No. 2

281--290

EN

The revision of classification methodologies for determination of soil expansivity revealed that parameters most frequently used for this purpose are: the liquid limit, plasticity index and swelling parameters which also predominate in older systems of expansive soil assessment, regarded as classical. Seventy-nine soil samples, including Neogene clays and glaciall tills from Central Poland, with a wide range of plasticity were examined for a comparative analysis of soil expansivity with a use of eight empirical methods. The study revealed that Neogene clays are mostly highly and very highly expansive, while glacial tills exhibit low to medium expansivity. Compared to classifications considering soil mineralogy indicators, those correlated solely to Atterberg limits and related parameters were found to overestimate soil expansivity. It is evident that the classifications are in better agreement for glacial tills than for clays. The comparison of mineral composition measured and predicted from swelling tests yielded consistent results.

11

Problemy projektowania i budowy kotwionej ściany szczelinowej w ekspansywnych iłach plioceńskich

Tomczak U.

Inżynieria i Budownictwo

|

2010

|

R. 66, nr 11

589-592

PL

Omówiono problemy związane z projektowaniem i budową ścian szczelinowych kotwionych kotwami gruntowymi, posadowionych w ekspansywnych iłach plioceńskich. Przedstawiono przykład realizacji obudowy wykopu budynku wzniesionego w Warszawie.

EN

An example of 80 cm thick diaphragm wall anchored with 1 level of ground anchors and 2 levels of steei struts in the corners, realized in expansive clays is presented. The bearing capacity of ground anchors is 750 kN and the length of grouted body 9 m. The realized diaphragm wall is the most economical ground support structure. It's also safe to the structure of nearby buildings as well as the environment (it does not influence the water level in the area).

12

Badania niezawodności eksploatacyjnej osnowy wysokościowej stabilizowanej na obszarze gruntów ekspansywnych

Derezińska A., Wolski B.

Czasopismo Techniczne. Środowisko

|

2008

|

R. 105, z. 2-Ś

85-94

PL

Na obszarze Bydgoszczy autorzy zrealizowali program badawczy dotyczący metodyki określenia niezawodności eksploatacyjnej osnowy wysokościowej. Niezbędne dane o warunkach wodno-gruntowych pozyskano, wykonując obszerne studium uwarunkowań środowiska. W artykule przedstawiono zakres studium, program i metodę badań oraz sposób interpretacji. W programie badań wyartykułowano specyficzne warunki stabilizacji punktów osnowy określone przez grunty ekspansywne dominujące na obszarze miasta. Przedstawiono algorytm analizy niezawodnościowej. Konkluzją badań jest stwierdzenie, że na obszarze gruntów ekspansywnych o niezawodności eksploatacyjnej punktów osnowy niwelacyjnej decyduje użytkowalność określona przez trwałość i dostępność znaków. Warunki wodno-gruntowe oddziałują na stabilność punktów osnowy w znacznie mniejszym stopniu.

EN

On the area of Bydgoszcz city the authors completed the research program on levelling network in the aspect of its operational reliability. The necessary data has been gathered by completion of the studies of environmental conditions. Research program, method and scope of studies as well as method of interpretation has been presented in the paper. The program has been focused at specific conditions of establishment of levelling network points determined by impact of expansive soils. The analysis of data gathered has been carried out according to original algorithm of operational reliability. As the main conclusion of the presented studies and analysis the authors point that on the area dominated by expansive soils the operational reliability depends on useability determined by damages and possibility of survey precedure completion. The impact of water and soil conditions on stability of bench marks is relatively small.

13

Podniesienie podłoża o właściwościach ekspansywnych i fundamentów

Ahmad D., Kuchler A.

Zeszyty Naukowe. Budownictwo / Politechnika Śląska

|

2003

|

z. 97

363-370

PL

Zainteresowanie gruntami ekspansywnymi jest żywotne i ważne. Występują one powszechnie w stanie nienasyconym i strefie [14] posadawiania obiektów budowlanych. Istnieje wiele metod do obliczania podniesienia podłoża spowodowanego pęcznieniem gruntów ekspansywnych, zarówno bez obciążenia, jak i z obciążeniem. W pracy dokonano porównania wyników obliczeń tego podniesienia wyznaczonego różnymi metodami w aspekcie wpływu podziału warstwy podłoża ekspansywnego na warstwy obliczeniowe, wpływu miąższości podłoża ekspansywnego oraz obciążenia zewnętrznego. W obliczeniach wykorzystano literaturowe parametry geotechniczne, średnie, minimalne i maksymalne, charakteryzujące grunty ekspansywne. Rozpatrzone metody prowadzą do wyraźnie zróżnicowanej wielkości podniesienia podłoża. Wykonane obliczenia i analizy wykazały złożoność problemu i potrzebę dalszych badań, ale nie tylko obliczeniowych, lecz także obejmujących obserwacje terenowe.

EN

The interest in expansive soils is important and vital. Expansive soils occur generally in unsaturated state and in the whole area of building foundations. There are lots of methods and formulas to calculate the raising of soil caused by swelling of expansive soils, either with the load or without it. The paper compares calculated results of raising, determined by different methods from the perspective of the influence of expansive soil layers fragmentation on calculated layers, the influence of the expansive soil thickness and the influence of external load. Literature geotechnical parameters, average, minimum and maximum, characteristic for the expansive soil, were used in the calculations. The methods considered lead to clearly differentiated expansive soil dimensions. The calculations and analyses made show the problem complexity and the need of further examinations, including site observations.

14

Zmiany wilgotności naturalnej iłów ekspansywnych po usunięciu grupy drzew na podstawie obserwacji poligonowych

Kumor M. K, Gorączko A.

Zeszyty Naukowe. Budownictwo i Inżynieria Środowiska / Akademia Techniczno-Rolnicza w Bydgoszczy

|

2001

|

Z. 33(239)

85-94

PL

W artykule przedstawiono wyniki wieloletnich obserwacji zmian wilgotności podłoża ekspansywnego zbudowanego z iłów trzeciorzędowych, poddanego oddziaływaniu dużej grupy drzew. Badania wykonano w skali naturalnej, na poligonie doświadczalnym Katedry Geotechniki Wydziału Budownictwa i Inżynierii Środowiska ATR. zlokalizowanym w Bydgoszczy przy ulicy Toruńskiej. Szczegółową analizą objęto zwłaszcza proces odbudowy wilgotności naturalnej w podłożu w okresie kilku lat po usunięciu roślinności. Podjęto także próbę analitycznego opisu redystrybucji wilgotności w funkcji głębokości i czasu, z uwzględnieniem cech geotechnicznych podłoża gruntowego.

EN

The present paper presents a multi-year observations of changes in expansive clay water content as affected by a considerably large group of deciduous trees. The research was conducted in the experimental field of the Department of Geotechnics, Faculty of Civil and Environmental Engineering of the University of Technology and Agriculture in Bydgoszcz. A thorough analysis covered, first of all, the process of natural water content restoration over a few years after cutting down the trees. An attempt has been made to provide an analysis of water content redistribution, including depth and time and geotechnical expansive clay.