Vane Shear Strength Research Articles

Field and laboratory investigation on geotechnical properties of sewage sludge disposed in a pit at Changan landfill, Chengdu, China

In order to find a proper treatment method for a sewage sludge disposal pit, field and laboratory investigation were conducted on the geotechnical properties of the sludge at the Changan landfill in Chengdu, China. The field investigation included borehole sampling, cone penetration tests and vane shear tests. The laboratory study involved the measurements of volume–mass relation, hydraulic conductivity, compressibility, coefficient of consolidation and shear strength for the borehole samples taken from the field. The field investigation revealed that the sludge in the disposal pit could be subdivided into three layers, i.e., top crust layer, middle fluid-like layer and deep soft plastic layer. The vane shear strength for the sludge was less than 1kPa at the fluid-like layer, and 1 and 3kPa at the deep soft plastic layer, being significantly lower than that of soft clay. Laboratory test results demonstrated that the sludge was high in organic content (18.5% to 51.8%) and water content (from 210% to 790%), and both of them exhibited a decreasing trend with depth. The variation in the organic content indicated a difference in the degree of biodegradation for the sludge at locations. The consolidation property and shear strength of the sludge exhibited a non-linear relationship to the applied consolidation pressure. The coefficient of consolidation of sewage sludge, decreasing with increasing consolidation pressure, was in an order of 10−5cm2/s to 10−6cm2/s, being 1–2 order lower than that of soft clay. The friction angle for the sludge increased from 10° for the pressure range from 0 to 100kPa to 15° for the pressure range from 100 to 400kPa.

Predicting geotechnical parameters of fine-grained dredged materials of the gulf of Izmit (NW Turkey) using the slump test method and index property correlations

2ABM Engineering Co., Izmit-Kocaeli, Turkey. Accepted 8 November, 2013 In this study, an attempt has been done to figure out the geotechnical properties of physically remolded dredged materials of the Gulf of Izmit located in NW Turkey, by using slump test method. For this aim, slum tests were conducted on dredged material specimens using open-ended polyvinyl chloride (PVC) cylinders of 10 cm diameter and height. Water content of the dredged material specimens was obtained in the laboratory using oven method. Bulk wet density, Atterberg limits and phase relations such as bulk unit weight, % solids by weight, void ratio, and engineering behavior properties such as Vane shear strength, and effective stress were determined. Later, the statistical correlations were conducted by regression analysis to obtain the relationships between water content and slump/cylinder height as well as other parameters such as wet bulk density, % solid by weight, void ratio, Vane shear strength and effective stress.

Discussion: Laboratory measurement of strength mobilisation in kaolin: link to stress history

CONTRIBUTION BY P. W. MAYNE While Vardanega et al. (2012) present an interesting empirical power law relationship for representing the stress– strain response of clays under constant volume, they must take care in the mixing and matching of different strength modes. In particular, the observed increase of normally consolidated undrained shear strength ratio (cu=s’v0)nc with plasticity index (Ip) given by equation (4) was specifically developed on the basis of raw (uncorrected) vane shear strengths measured in the field on natural clays. The general trend for the shear strength ratio from field vane tests (FVTs) varying with Ip is reported by Bjerrum (1972), Larsson (1980), Jamiolkowski et al. (1985), Chandler (1988) and Leroueil & Hight (2003), albeit using non-linear relationships such as power law rather than the original linear form. On the other hand, the general trend for the strength ratio (cu=s’v0)nc from triaxial compression (TC) tests on clays shows essentially no dependence on Ip (Larsson, 1980; Jamiolkowski et al., 1985; Ladd, 1991; Ladd & DeGroot, 2003). As a consequence, this fact led Chandler (1988) to recommend an Ip expression that inter-relates FVT strengths to equivalent TC values. Figure 9 shows the trends of (cu=s’v0)nc versus Ip using the original FVT dataset of Skempton (1957) and the laboratory dataset from TC, direct simple shear and triaxial extension modes presented by Ladd & DeGroot (2003). While the FVT data show a strong correlation with Ip (r 2 5 0?946), the TC data do not (r 5 0?0002). These trends have been supported by larger datasets including over 200 vane shear test (VST) data and over 200 laboratory strength data (Mayne, 2012). On the other hand, as per the theoretical link established by critical state soil mechanics, the ratio (cu=s’v0)nc for TC mode increases with the effective stress friction angle w9 of the clay, as verified elsewhere (Mayne, 1988, 2012).

Shear Strength Behavior of Cement/Lime-Solidified Dunkirk Sediments by Fall Cone Tests and Vane Shear Tests

Abstract An attempt has been made to use the fall cone tests and the laboratory vane shear tests for measuring the undrained shear strength of cement/lime-solidified sediments from Dunkirk Port in France. The results of the fall cone tests and the laboratory vane tests performed on Dunkirk sediments are discussed. First, the relationship between the vane shear strength and the water content is explored. Second, the relationship between the depth of cone penetration and the water content is studied. Third, the relationship between the shear strength by the fall cone test and the depth of cone penetration is evaluated. Fourth, the relationship between the shear strength by the fall cone test and the water content is investigated. Finally, the comparison of undrained shear strength performed by the fall cone test and the vane shear test is performed.

Effect of Soil Conditioners on the Pressure and Rate-Dependent Shear Strength of Different Clays

Tunneling using the earth pressure balance machines method in clayey soils requires the addition of conditioning chemicals to reduce the torque moment of the machine and to guarantee a safe and economical excavation process. Injection of foams and polymers at the cutter head of the tunnel boring machine with subsequent remolding in the pressure chamber transforms the excavated material into a deformable soil paste with preferably low strength and adhesion. The soil becomes more compressible and can develop viscous properties, such that the pressure and rate dependency of the shear strength of the mixtures are of major importance for the proper design and analysis of the tunneling processes. In this paper, the results of vane shear strength measurements on various conditioned clays and clay-sand mixtures at various shearing velocities and applied pressures are presented and analyzed. The results clearly show the effects of the chemicals used and also point out the differences in their efficiency depending on the clay mineralogy. This allows for an improved understanding of the working mechanisms of the chemicals.

Discussion of “Evaluation of Undrained Shear Strength Using Full-Flow Penetrometers” by Jason T. DeJong, Nicholas J. Yafrate, and Don J. DeGroot

The authors have presented an important empirical analysis of the resistance factors of the T-bar and ball full-flow penetrometers. The analysis is comprehensive, involving measurements from numerous field tests around the world. Commonly, the resistance of the full-flow penetrometers is expressed using a resistance factor: N 1⁄4 ðP∕AÞ∕su 1⁄4 q∕su, where P is the penetration force, A is the projected area, q is the penetration resistance, and su is the undrained shear strength of the soil. By selecting the field vane shear strength, suðFVTÞ, as a reference value for su, the authors were able to obtain a robust relationship between the soil sensitivity, ST , and the resistance factor, N. The approach, analyses and results presented in the paper are supported mostly by the experimental data. There is a brief comparison to the N values derived from analytical solutions, but without a clear indication of the reference shear strength associated with the solutions (e.g., FVT, CAUC). The aim of this discussion is to supplement the presented empirical work with detailed analytically based results. Klar and Pinkert recently presented (2010) a new method for obtaining a steady-state solution for full-flow penetrometers. The method does not utilize a large strain remeshing approach as applied in the works of Zhou and Randolph (2007, 2009), but instead solves the problem as a small strain classical plasticity problem, in which time changes of the material properties are converted into a spatial distribution of strength using topological ordering. Specific details about the method and its validity may be found in Klar and Pinkert (2010). For each of the penetrometers (i.e., T-bar and ball) the theoretically calculated resistance factor may be expressed as a function of several fundamental parameters

Analysis of Shear Strength Parameters on Soft Clay Slope Stability at Short Term

The slope stability is an important problem for the slope building on the soft clay ground. At present, the vane shear strength is common used to calculate the factor of slope stability at short term. In fact, a lot of cases show that the vane shear strength underestimates the real shear strength of the sliding surface. Therefore, based on Mohr-Coulomb theory, and using the linear relation between the vane shear strength and the depth, a method of converting in-situ vane shear strength into undrained shear strength parameter is presented. Two shear strength parameters c and φ are from statistical regression analysis. The anisotropy, the lateral compression coefficient and the average consolidation degree of the soft clay are considered. The two shear strength parameters are used to calculate the short term safety factor of the slope stability. The safety factor is greater than 1.0 for steady slope.

Saltmarsh creek bank stability: Biostabilisation and consolidation with depth

The stability of cohesive sediments of a saltmarsh in Southern England was measured in the field and the laboratory using a Cohesive Strength Meter (CSM) and a shear vane apparatus. Cores and sediment samples were collected from two tidal creek banks, covered by Atriplex portulacoides (Sea Purslane) and Juncus maritimus (Sea Rush), respectively. The objectives of the study were to examine the variation of sediment stability throughout banks with cantilevers present and investigate the influence of roots and downcore consolidation on bank stability. Data on erosion threshold and shear strength were interpreted with reference to bank depth, sediment properties and biological influences. The higher average erosion threshold was from the Sea Purslane bank whilst the Sea Rush bank showed higher average vane shear strength. The vertical variation in core sediment stability was mainly affected by roots and downcore consolidation with depth. The data obtained from the bank faces revealed that vertical variations in both erosion threshold and vane shear strength were affected primarily by roots and algae. A quantitative estimate of the relative contributions of roots and downcore consolidation to bank sediment stability was undertaken using the bank stability data and sediment density data. This showed that roots contributed more to the Sea Purslane bank stability than downcore consolidation, whilst downcore consolidation has more pronounced effects on the Sea Rush bank stability.

MD179調査より得られた日本海東縁域海底表層堆積土の物理・力学的性質

Gas hydrates are attracting attention as a next-generation energy source. On the other hands, Methane gas contained in the natural gas hydrates has approximately 20 times the greenhouse effect of CO2. There are concerns that dissociation of methane gas from the gas hydrates distributed in submarine surface layers (shallow type gas hydrates) by rising ocean temperatures or by vaporization at recovery of the hydrates for energy may contribute to global warming, which in turn may raise the sea level and causing climatic instability. In addition, many gas-hydrate-bearing areas are distributed near the boundaries of tectonic plates, as shown in the figure. Gas hydrates in the surface layer of seafloor may dissociate when seismic activities cause seafloor landslides that in turn cause gas hydrate-bearing layers to fail. There have been concerns over the environmental effects of shallow type gas hydrates, but surveys for shallow type hydrates have been few.The purpose of this study is to understand the soil properties of the sea-bottom sediment obtained from the Eastern Margin of Japan Sea. The samples were collected from 5 regions (Umitaka Spur, Joetsu Ridge, Toyama Trough, West of Tsugaru and west of Okushiri Ridge), and the physical (soil density and water content) and mechanical (cone penetration ratio and vane shear strength) tests were performed by on-board used for the sea-bottom sediments.From the test results, it is found that the physical properties of the sediment samples obtained in these areas have no marked difference regardless of the locations or depth of sampling. However, the soil strength of sea-bottom sediments obtained gas hydrates was lower than those of other sediments. It would seem that this is because the effect of methane hydrates dissociation and vaporization of dissolved gas in the pore water at sampling.

高含水比状態における海成粘土の流動特性

The flow properties of marine clays, the water content of which are much larger than the liquid limit are studied experimentally. A series of vane shear tests and rotary viscometer tests were carried out with four marine clays with different water contents larger than the liquid limit. It was found that the yield stresses obtained by the viscometer were closely related with the water contents normalized by liquid limit. Using water content normalized by the liquid limit, a unique relationship between shear stress and shear rate is obtained. As a result, it was known that the flow properties of marine clays with high water content can be estimated by knowing the normalized water content or vane shear strength. These findings are useful to consider the wave-mud interaction problem.

Application of Dynamic-Static Drainage Consolidation Method on a Silty Ground of Guangzhou

The treatment of a silty ground for petroleum product storage facilities in Guangzhou with dynamic-static drainage consolidation method which is based on based on combining the dynamic compaction method and the static consolidation is presented. The pore water pressure, settlement, field vane shear strength, bearing capacity through plate load tests have clearly shown that this method can significantly strengthen the silt ground within reasonable time frame. The soft ground has been improved under the dynamic and static forces and their residual effects.

Influence of Pore Fluid Viscosity on the Dynamic Properties of an Artificial Clay

This paper presents the results of vane shear, laboratory compaction, isotropic consolidation, cyclic triaxial, bender element, and resonant-column tests that were performed to characterize the dynamic properties of an artificial soil called modified glyben. Modified glyben comprises a mixture of glycerin, water, and bentonite that can be used in scaled model tests performed at 1 G or n G in a centrifuge to study seismic soil–structure interaction. The results described in this paper show that the vane shear strength, coefficient of consolidation, dynamic modulus, and damping ratio are strongly influenced by the viscosity of the pore fluid which can be varied by altering the ratio of glycerin-to-water. In addition, the properties of modified glyben are stable during prolonged exposure to air and multiple largestrain load cycles making it a suitable model soil for scaled model tests involving seismic soil–structure interaction.

Effects of cattle grazing during the dormant season on soil surface hydrology and physical quality in a moist‐temperate region

AbstractLivestock grazing in paddocks of temperate regions during the dormant season affects soil surface hydrology and physical quality, thus, impacting its capacity to function. However, very few studies have dealt with these effects in temperate‐moist regions. Thus, the objective of this study was to evaluate the effects of grazing on these variables, with reference to soil hydrological and physical characteristics. Soil properties were measured in a paddock under rotational grazing during the growing season only (GR) and compared with those under grazing during the dormant season and rotational grazing during the growing season (DO). Soil series in both paddocks is Coshocton (fine loamy, mixed, active, mesic Aquultic Hapludalfs). Soil properties were studied for 0–5, 5–10 and 10–15 cm depths. In comparison with GR, DO had a smaller soil water sorptivity (36·2 vs 19·4 mm min−0·5), transmissivity (2·2 vs 0·6 mm min−1), equilibrium infiltration rate (4·8 vs 1·4 mm min−1) and cumulative infiltration in 3 h (865·6 vs 260·0 mm). In addition, GR had larger volumetric field moisture capacity (41·4 vs 39·3%), water stable aggregates (880 vs 830 g kg−1), coarse root (>1 mm) biomass (12·8 vs 7·2 mg cm−3), smaller penetration resistance (0·93 vs 1·42 MPa) and bulk density (1·24 vs 1·44 g cm−3). A small difference between GR and DO was observed in vane shear strength (130·3 vs 124·8 kPa), and no difference was found in aggregate's mean weight diameter. Soil properties differed among depths, and the effect of grazing decreased with increased depth. Copyright © 2010 John Wiley & Sons, Ltd.

Influence of Shear Rate on Undrained Vane Shear Strength of Organic Harbor Mud

Dredging operations in European harbors for maintenance of navigable water depth produce vast amounts of harbor mud. Between 2005 and 2007, the second largest harbor construction project in Germany was designed as a pilot study to use dredged harbor mud as backfill material to avoid expensive disposal or ex situ treatment. During this project, a partial collapse of the backfill highlighted the need for an improved assessment of undrained shear strength of naturally occurring liquid harbor mud. Using vane shear testing, this study evaluates the effect of shear rate on the undrained shear strength of harbor mud. It is shown that measured values for both peak and residual shear strength are significantly influenced by shear rate effects. Furthermore, the influence of shear rate on the peak shear strength is found to be independent of water content while the influence of the shear rate on the residual shear strength strongly depends on water content. New shear rate dependent correction factors μ are proposed ...

Mechanical weeding effects on soil structure under field carrots (Daucus carota L.) and beans (Vicia faba L.)

AbstractThe successful production of organic vegetables relies heavily on mechanical weeding, flame weeding and stale seedbeds. These operations involve repeated passes by tractors. Mechanical weeding also involves regular tillage. This combination of repeated tillage and compaction changes soil structure. We studied these structural changes in two fields of organic carrots and one field of beans in eastern Scotland. Structure was described by measuring soil strength with a vane shear tester and a cone penetrometer, by measuring bulk density and by visual assessment. Under beans, vane shear strength below the growing root zone was highly variable and in some areas was high enough to restrict root growth (>50 kPa). The carrots were grown in beds containing crop rows separated by bare soil. The bare soil was regularly weeded mechanically. The structure of this weeded soil in the top 10 cm layer of a loam eventually became disrupted and compacted enough to deter root growth (vane shear strength of 70 kPa). In addition the topsoil and subsoil in the wheel‐tracks between the beds became very compact with little distinguishable structure. This compaction extended to the subsoil and persisted into the next cropping season (cone resistance >3 MPa at 35–50 cm depth). Reduced tillage by discing without ploughing was used to incorporate the straw used to protect the carrots overwinter and prepare the soil for the next crop. The resulting topsoil quality was poor leading to anaerobic growing conditions which restricted growth of the following crop and led to losses of the greenhouse gas nitrous oxide. The greatest threat to soil quality posed by mechanical weeding was subsoil compaction by tractor wheeling.

Evaluation of Remolded Shear Strength and Sensitivity of Soft Clay Using Full-Flow Penetrometers

The undrained remolded shear strength of soft clays is of importance in geosystem design, particularly for offshore structures. Common methods to estimate remolded shear strength, such as correlations with cone penetration data, direct measurement with an in situ field vane shear device, and laboratory measurements, produce varied results and can be particularly costly and time consuming. Full-flow penetrometers (T-bar and Ball) provide an alternative rapid method to estimate remolded shear strength and soil sensitivity through remolding soil by repeated cycling of the penetrometer up and down over a given depth interval. The cyclic penetration resistance degradation curve inherently contains information regarding remolded strength and sensitivity. The objective of this paper is to assess the ability of full-flow penetrometers to predict remolded strength and soil sensitivity, and to develop a suite of predictive correlations in which these properties can be estimated in the absence of complementary laboratory or in situ test data. To accomplish this, full-flow penetration profiles and cyclic tests were performed at five well characterized soft clay sites, which together represent the broad range of soils in which the penetrometers will be often used. A previously developed model for the reduction in penetration resistance with cycling is modified to predict the entire degradation curve, including the remolded penetration resistance using only measurements obtained during initial penetrometer penetration and extraction. Using field vane shear strength as the reference measurement, correlations are developed to predict soil sensitivity and remolded shear strength based solely on full-flow penetrometer data, which is particularly useful in site investigation programs where site specific data are not yet available or are sparse. Finally, the usefulness of these relationships is demonstrated by implementing them for two additional soft clay sites.

Visual assessment of soil structure: Evaluation of methodologies on sites in Canada, China and Germany: Part I: Comparing visual methods and linking them with soil physical data and grain yield of cereals

Visual observations of soil structure in the field offer the potential of semi-quantitative information for use in extension and monitoring. The aim of the study was to test the diagnostic value of different visual methods of soil structure assessment in relation to measurements of topsoil physical quality and yield of cereals. Visual methods that emphasized aggregate and pore characteristics were considered and included procedures of Peerlkamp [Peerlkamp, P.K., 1967. Visual estimation of soil structure. In: de Boodt, M., de Leenherr, D.E., Frese, H., Low, A.J., Peerlkamp, P.K. (Eds.), West European Methods for Soil Structure Determination, vol. 2, no. 11. State Faculty Agric. Sci., Ghent, Belgium, pp. 216–223], Diez and Weigelt [Diez, T., Weigelt, H., 1997. Bodenstruktur erkennen und beurteilen. Anleitung zur Bodenuntersuchung mit dem Spaten. Sonderdruck diz agrarmagazin. Bayer. Landesanstalt fuer Bodenkultur und Pflanzenbau, Freising-Muenchen., 2nd ed., 16 pp.], Shepherd [Shepherd, T.G., 2000. Visual Soil Assessment. Volume 1. Field Guide for Cropping and Pastoral Grazing on Flat to Rolling Country. Horizons.mw/Landcare Research, Palmerston North, 84 pp.], Werner and Thaemert [Werner, D., Thaemert, W., 1989. Zur Diagnose des physikalischen Bodenzustandes auf Produktionsflaechen. Arch. Acker-Pflanzenbau Bodenkd., Berlin 33, 729–739], FAO [FAO, 2006. Guidelines for soil description, 4th ed. FAO, Rome, 95 pp.] and the Peerlkamp method, modified by [Ball, B.C., Batey, T., Munkholm, L.J., 2007. Field assessment of soil structural quality—a development of the Peerlkamp test. Soil Use and Management 23, 329–337]. Measurements of soil quality included soil density (DBD), strength (penetrometer resistance, vane shear strength), permeability (initial infiltration rate) and biological activity (earthworm counts). The study was conducted on sites in Canada (Elora), China (Luancheng), and Germany (Dedelow). Soils were loamy and silty textured Haplic Luvisols (Elora, Dedelow) and Haplic Cambisols (Luancheng). Results showed that shape and size of aggregates were quickly recognizable diagnostic features of soil structure. Structure scores of most methods gave similar results after standardizing data. Measured soil physical qualities and crop yields correlated significantly with visual soil structure. Unfavourable visual structure was associated with increased dry bulk density, higher soil strength and lower infiltration rate but correlations were site-specific. Biological features like earthworm or root numbers were less reliable indicators of soil structure than aggregate characteristics. Visual soil structure assessment is a useful diagnostic tool and may indicate soil structure states clearly. Methods should be selected according to site conditions and should include a fast method of the Peerlkamp type.

有明海湾奥部における懸濁物質濃度変動特性に関する研究

Suspended sediment concentration and current velocity were measured continuously by Acoustic Doppler Current Profiler at the inner part of the Ariake Sound. Simultaneously, shear strength of the surface of the bottom mud was measured around the mooring point. Shear strength which measured by viscosity meter had finer relationships between vane shear strength. Multiple regression analysis was applied to the maximum SS concentration in every 15 hours. The main factor of the variation of the SS was the bottom shear stress. Sub-factor of the variation of SS concentration were wind velocity and the shear strength of the surface bottom mud.

Heat flow distribution on the floor of Nankai Trough off Kumano and implications for the geothermal regime of subducting sediments

During three research cruises (KY05-14, KY07-01 and KY08-01) using JASMTEC R/V KAIYO, we obtained 13 heat flow data with piston core samples across the Nankai Trough and the Kashinosaki Knoll (KK). Subbottom temperatures were measured by precise thermometers attached to the piston corer. Thermal conductivity, color reflectance and vane shear strength were measured for the cored samples onboard KAIYO. Surface heat flow in the Nankai Trough north of KK ranges from 90135 mW/m 2 . With the sedimentation effects considered, basal heat flux beneath the Nankai Trough off Kumano is roughly estimated as 100-130 mW/m 2 , most likely as 120-130 mW/m 2 . In the Shikoku Basin south of KK, heat flow ranges 120-147 mW/m 2 , (average~135 mW/m 2 ), significantly higher than the theoretical value (110 mW/m 2 ) estimated from the age of the Shikoku Basin. Possible cause for the heat flow anomaly is either the postspreading volcanism at KK, thermal disturbance by tectonic compression at KK, or subseafloor fluid migration. More intensive study, including scientific drilling is necessary to estimate the accurate thermal structure of the incoming Shikoku Basin.

Engineering Properties of Fibrous Peats

This state-of-the-art paper presents an interpretation of the permeability, compressibility, and shear strength of fibrous peats using data from laboratory tests on undisturbed block samples of two fibrous peats, as well as extensive laboratory and field data from the literature on fibrous peat deposits. Engineering properties of fibrous peats are significantly different from those of most inorganic soils. However, the same fundamental mechanisms and factors determine behavior of both inorganic soils and fibrous peats. Fibrous peat deposits possess very high initial permeability, typically 1,000 times the initial permeability of soft clay and silt deposits. Upon compression, the permeability of fibrous peats decreases dramatically, with a ratio of permeability change index to in situ void ratio equal to 0.25, as compared to 0.50 for soft clay and silt deposits. Fibrous peats display extreme compressibility to the increase in effective vertical stress, with compression index values right after preconsolidation pressure 5 to 20 times the corresponding compressibility of typical soft clay and silt deposits. Among geotechnical materials, fibrous peats display the highest ratios of secondary compression index to compression index, in the range of 0.05 to 0.07. The values of coefficient of earth pressure at rest for normally consolidated young fibrous peat deposits are in the range of 0.30 to 0.35, as compared to 0.45 to 0.65 for inorganic soils. The values of friction angle from triaxial compression tests for fibrous peats are in the range of 40 to 60°, as compared to less than 35° for soft clay and silt compositions. For fibrous peats, the ratios of undrained shear strength in compression to preconsolidation pressure are usually in the range of 0.50 to 0.75, as compared to 0.32 for soft clay and silt deposits. For surficial fibrous peat deposits the ratio of vane shear strength to preconsolidation pressure is near 1.0, as compared to 0.12 to 0.35 for inorganic soft clay and silt deposits. For fibrous peats, the ratio of undrained Young's modulus to undrained shear strength is in the range of 20 to 80.