The Relation between Moisture Content and Share Strength of Swelling Soft Rock in the North of Xianfeng Town Open-Cast Coal

2014 ◽  
Vol 971-973 ◽  
pp. 2168-2171
Author(s):  
Qing Shui Liu ◽  
Ying Hui Chen ◽  
Wen Lian Liu
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Soft Rock ◽  
Soil Mass ◽  
Soaking Time ◽  
The North ◽  
Disturbed Soil ◽  
Strength Tests ◽  
The Stability ◽  
Open Cast

We did sorts of shear strength tests in different moisture content conditions with amount of disturbed soil which was collected from the swelling soft rock in the north of xianfeng town open-cast coal. Furthermore, we analyzed the physical relationships between moisture content of the rock-soil mass and shear strength under different soaking time or different moisture content conditions. Finally, we find the shear strength of rock-soil mass drops along with the saturated degree of test specimen doubled and re-doubled. We get a conclusion that soaking of the rock-soil mass has a strong influence on the strength of rock-soil mass. The soaking of groundwater and surface water could soft the rock-soil mass, which plays an important role in controlling the stability of side slope, also in continuing slip deformation.

Seasonal changes in diatom biomass, sediment stability and biogenic stabilization in the Severn Estuary

1993 ◽  
Vol 73 (4) ◽  
pp. 871-887 ◽  
Author(s):  
Graham J. C. Underwood ◽  
David M. Paterson
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Surface Sediments ◽  
Critical Shear Stress ◽  
Strongly Correlated ◽  
Sediment Stability ◽  
Severn Estuary ◽  
Epipelic Diatoms ◽  
The Stability ◽  
Better Than

Epipelic diatoms represented the dominant microphy tobenthos on the intertidal mudflats of the Severn Estuary, south-western Britain. Algal biomass (measured as chlorophyllaconcentration) varied over a seasonal cycle and was strongly correlated with sediment shear strength and critical shear stress and therefore with position on the shore. High levels of diatom biomass were positively correlated with the concentration of colloidal carbohydrate within the surface sediments. The critical shear strength for incipient erosion was significantly correlated with position on the shore (moisture content) and with both chlorophyllaand colloidal carbohydrate, the latter being the best biochemical predictor for the incipient erosion threshold. The range of stress required to cause incipient erosion varied from 1.0 to 8.0 N m-2, with the sediment increasing in resistance landwards. Two-way analysis of variance using both moisture content and colloidal carbohydrate as variables explained the stability of the sediment better than individual pair-wise comparisons.

scholarly journals A Theoretical Calculation Method of the Unsupported Span for the Shallow Tunnel in the Soft Stratum

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xiaoxu Tian ◽  
Zhanping Song ◽  
Guannan Zhou ◽  
Xiaowei Zhang
Keyword(s):  
Soft Rock ◽  
Friction Angle ◽  
Soil Mass ◽  
Calculation Model ◽  
Support Pressure ◽  
Shallow Tunnel ◽  
Tunnel Face ◽  
Rock Stratum ◽  
The Stability ◽  
Shallow Buried Tunnel

During the construction of the tunnel in soft stratum, it is often found that the unsupported span is too large, resulting in instability of the tunnel face and collapse of the vault. However, the unsupported span was often selected according to the experience of engineers in the actual construction process, which was lack of the theoretical basis. Therefore, based on the calculation model of the surrounding rock pressure of shallow buried tunnel, this paper analyzed the stability of the tunnel face and the vault and then obtained the calculation formula of the unsupported span of the shallow buried tunnel in soft rock stratum. It was pointed out that the unsupported span is not determined by the arch crown stability or the tunnel face stability alone, but by both. The rationality of the formula was verified by a centrifugal test and an engineering case. The analysis and discussion showed that the unsupported span is sensitive to the cohesion and internal friction angle of the rock-soil mass, especially the cohesion. The unsupported span of the shallow buried tunnel in the soft rock stratum is a linear function of the support pressure. The support pressure has a more significant contribution to the increase of the unsupported span by the centre cross diaphragm (CRD) method, and the unsupported span increases linearly with the increase of the support pressure. The research results provide a theoretical reference for the determination of the unsupported span for the shallow tunnel in the soft stratum.

scholarly journals Influence of moisture content of cohesive soils on their shear strength

2017 ◽  
Vol 2017 (5) ◽  
pp. 10-19 ◽  
Author(s):  
Tymoteusz Zydroń ◽  
Małgorzata Wojciechowska-Dymańska ◽  
Andrzej Gruchot ◽  
Tomasz Zalewski
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Optimum Moisture Content ◽  
Cohesive Soils ◽  
Test Results ◽  
Angle Of Internal Friction ◽  
Shearing Rate ◽  
Strength Tests ◽  
Shear Box ◽  
Direct Shear Apparatus

Influence of moisture content of two cohesive soils on their shear strength was the purpose of the tests. The shear strength tests were carried out in a standard direct shear apparatus of dimensions of the box 6 x 6 x 1,8 cm. Each sample of assumed moisture content was preliminary compacted at Proctor apparatus, then was cut using a square cutter and to set into the shear box. Each series of samples were tested at four values of moisture content: equal, lower and higher than optimum moisture content. One series of samples, sheared at moisture content higher than optimum moisture content, the shearbox during consolidation and shearing was filled with the water to the level corresponding to shearing plane. Main tests were done using shearing rate equal to 1,0 mm.min-1 and time of consolidation was equal to 12 hours. Additional tests were done using shearing rate equal to 0,05 mm.min-1 and the samples during consolidation and shearing were saturated. Test results revealed that the most beneficial values of shear strength were obtained at optimum moisture content or lower that optimum moisture content. It stated that the increase of moisture content cause decrease of angle of internal friction and the highest values of cohesion was obtained at optimum moisture content. Comparison of test results obtained for series of samples sheared at optimum moisture content revealed that saturation of soil sample and low shearing rate cause very significant reduction of obtained values of cohesion.

Experimental Study of the Creep Disturbance Effect and Acoustic Emission Characteristics of Mudstone with Different Moisture Contents

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Yongjiang Yu ◽  
Pengbo Wang ◽  
Shipeng Zhang ◽  
Jingjing Liu
Keyword(s):  
Acoustic Emission ◽  
Moisture Content ◽  
Soft Rock ◽  
Clear Understanding ◽  
Creep Failure ◽  
Soft Rocks ◽  
Moisture Contents ◽  
Accelerated Creep ◽  
The Stability ◽  
The Impact

It is important to have a clear understanding of the creep characteristics of water-rich soft rocks under a dynamic load and the evolution of cracks because soft rock roadways in deep mines are very sensitive to disturbances, and instability and damage can easily occur under the impact of disturbances such as mining and blasting. In this study, a self-developed disturbed creep test bench was used to conduct graded loading creep disturbance tests on mudstone specimens with different moisture contents. The results show that an increase in the moisture content leads to a significant increase in the creep failure strain of mudstone, and the accelerated creep rate is greatly accelerated. Moreover, as the moisture content increases, the type of mudstone creep disturbance failure gradually changes from accelerated creep failure to disturbance failure. By analyzing the acoustic emission (AE) characteristics of the mudstone creep disturbance tests, it was found that the increase in the moisture content greatly weakens the AE count and the accumulated energy. In each stage of disturbance, the AE signals jumped, and the stability was restored at the end of the disturbance. As the load increased, the specimen entered the accelerated creep stage, the AE signal increased exponentially, and the internal cracks expanded rapidly until failure occurred. It is of great significance to carry out creep disturbance experiments and to analyze the evolution of the internal cracks in specimens with different moisture contents to maintain the long-term stability of deep soft rocks.

Shear Strength of Soils

2015 ◽  
pp. 249-312
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Continuum Mechanics ◽  
Geotechnical Engineering ◽  
Soil Mass ◽  
Physico Chemical ◽  
Soil Deposits ◽  
Intrinsic Capacity ◽  
The Stability ◽  
Multi Phase

Shear strength is a very important property of soils. The concept is used by geotechnical engineers in estimating the bearing capacity of foundations and in assessing the stability of retaining walls, slopes, and embankments and the design and construction of highway and airfield pavements. The shear strength of a soil can be regarded as its intrinsic capacity to resist failure when forces act on the soil mass. The strength is a function of the type as well as the physico-chemical make-up of the soil. This chapter explores the strength theories that are used in geotechnical engineering and which derive essentially from the classical theories of elasticity and plasticity. Such theories are usually modified when used by soil engineers in recognition of the discrete and multi-phase nature of soil deposits. It is important therefore to understand some of the fundamental concepts or hypothesis of continuum mechanics to be able to appreciate the limitations and applicability of strength theories in geotechnical engineering.

The stability of stage-constructed embankments on soft clays

1978 ◽  
Vol 15 (2) ◽  
pp. 283-305 ◽  
Author(s):  
F. Tavenas ◽  
R. Blanchet ◽  
R. Garneau ◽  
S. Leroueil
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Text Analysis ◽  
Factor Of Safety ◽  
Initial Period ◽  
Stability Conditions ◽  
Soft Clays ◽  
North Shore ◽  
The North ◽  
The Stability

The stage construction of seven high embankments on soft clays on the north shore of the St. Lawrence Valley has provided an excellent opportunity to check the applicability of the concepts of limit and critical states to the analysis of the behaviour of clay foundations.The construction pore pressures have confirmed the development of a significant consolidation in the initial period of construction.The consequences of this consolidation on the behaviour of the clay, in particular in terms of available strength, and on the method of stability analysis have been found entirely consistent with the general model proposed by Leroueil, Tavenas, Mieussens and Peignaud.It is suggested that the so-called [Formula: see text] analysis based on the vane shear strength corrected according to Bjerrum gives the minimum factor of safety and may be too conservative during stage construction. Effective stress analyses are shown to be more representative of the true stability conditions, and they have been successfully used to accelerate the construction of the embankments.

scholarly journals INFLUENCE OF CEMENT – SODIUM SILICATE GROUT ADMIXED WITH CALCIUM CHLORIDE AND KAOLINITE ON SAPRIC PEAT / SAPROGENINIŲ DURPIŲ POVEIKIS CEMENTO IR NATRIO SILIKATO SKIEDINIO SU KALCIO CHLORIDU BEI KAOLINITU SAVYBĖMS

2011 ◽  
Vol 17 (3) ◽  
pp. 309-318 ◽  
Author(s):  
Sina Kazemian ◽  
Arun Prasad ◽  
Bujang B. K. Huat ◽  
Jafar Bolouri Bazaz ◽  
Farah N. A. Abdul Aziz ◽  
...  
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Calcium Chloride ◽  
Sodium Silicate ◽  
Organic Content ◽  
Silicate System ◽  
Net Charge ◽  
Soaking Time ◽  
Porous Microstructure ◽  
High Organic Content

Sapric peat is extremely soft, unconsolidated and has high organic content. It is most decomposed peat with less fiber content among all peats. This paper investigates the effectiveness of using different ratios of cement–sodium silicate system grout compounds with kaolinite in mechanical property (shear strength) and micro–structural properties (SEM and EDX) of sapric peat samples after 3 and 30 days of curing. The study showed that the kaolinite was effective in increasing the shear strength and reducing the moisture content of the treated peat. Calcium chloride seemed to have different effects on the grouts strength. It caused to increased shear strength of samples until the net charge of the sample changed to zero and then it decreased with further increase in calcium chloride. By increasing sodium silicate (within 3%), cement and soaking time on treated peat, it was observed that they are able to increase the shear strength and density with a corresponding decrease in moisture content, porous microstructure, and the multitude of voids of confection. Santrauka Durpės, susidarančios pūvant, yra ypač minkštos, nevienalytės struktūros, turi daug organikos. Durpių struktūra yra chaotiška, jose mažai fibrų. Šiame darbe nagrinėjamos skirtingų skiedinių (cemento ir natrio silikato su pūvant susidarančiomis durpėmis ir kaolinitu) mechaninės (šlyties stipris) ir mikrostruktūrinės savybės (SEM ir EDX) po 3, 30 ir 90 dienų. Nustatytas tokių durpių ir kitų priedų naudojimo veiksmingumas skiediniuose. Tyrimai parodė, kad kaolinito priedas padidina šlyties stiprį ir sumažina durpių vandens poreikį. Taip pat nustatyta, kad kalcio chloridas gali skirtingai veikti skiedinių stiprį. Įvertinta, kad bandinių šlyties stipris didėja, kai kalcio chlorido kiekis mišinyje artimas nuliui, didinant kalcio chlorido kiekį, stipris mažeja. Atlikus tyrimus pastebėta, kad didinant natrio silikato, cemento kiekį ir ilginant apdorotų durpių įmirkymo laiką, bandinių šlyties stipris ir tankis didėja, mažėja vandens poreikis ir tuštumų skaičius, kinta mikrostruktūros parametrai.

scholarly journals Dependence of physico-mechanical characteristics and safety factor of the soil mass on the spacing of vertical pillars of crushed stone

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Igor Artyushenko
Keyword(s):  
Soil Mass ◽  
Climatic Conditions ◽  
Transport Infrastructure ◽  
Strength Characteristics ◽  
Crushed Stone ◽  
Soil Base ◽  
Railway Line ◽  
The North ◽  
Permafrost Soils ◽  
The Stability

In the design, construction and further operation of communication lines on permafrost soils, the most urgent task is to ensure the reliability of the foundation of the structure. The complexity of construction in the North is due to the presence of permafrost soils in the foundations of buildings, a large number of natural barriers, extreme climatic conditions and lack of infrastructure. In this regard, the choice of structural, technological and organizational solutions for the development of transport infrastructure, including for railways and, first of all, a deformability forecast, measures to ensure the stability of the soil base and the development of rational organizational schemes for their implementation, should be economically feasible, optimal or close to optimal for a particular engineering structure and the region of its location. To ensure stability and sustainability of the soil base of the structure on the Northern Latitudinal Railway section of the new Obskaya-Salekhard railway line, PK 01+50 – PK 06+50, the author proposes a solution to strengthen the base soil with vertical columns of crushed stone. This article shows the effect of vertical columns of crushed stone on the strength characteristics of permafrost soils of the base of the structure. The dependence of the strength characteristics of the soil base on the different steps of the placement of vertical columns of crushed stone is shown. The conclusion is drawn about the most optimal spacing step according to the results of calculations and comparison of various steps of arranging vertical pillars from crushed stone. The results presented in the article are part of the dissertation research I. Artyushenko «Reinforcement of the subgrade base with vertical columns of crushed stone in areas with permafrost soils».

Slope Stability Analysis under the Condition of Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 241-245
Author(s):  
Yang Jin
Keyword(s):  
Finite Element Method ◽  
Shear Strength ◽  
Slope Stability ◽  
Negative Impact ◽  
Strength Reduction ◽  
Soil Slope ◽  
Failure State ◽  
Calculation Results ◽  
The Stability ◽  
Shear Strength Reduction

The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

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