Pressuremeter Tests Research Articles

Lychnophora pinaster's effects on inflammation and pain in acute gout

Ethnopharmacological relevanceEthanolic extract of aerial parts from Lychnophora pinaster Mart. are used in traditional Brazilian medicine for treating pain, rheumatism and inflammation. Aim of the studyDrugs for the treatment of gout present severe adverse effects, justifying the need to search for new therapeutic options. The aim of the present study was to evaluate the effects of the ethanolic extract of L. pinaster and its main constituents in arthritis induced in mice by the injection of monosodium urate (MSU) crystals. Materials and methodsAntinociceptive effect was investigated using an electronic pressure-meter nociception paw test in C57BL/6 mice. Anti-gouty arthritis was investigated in mice induced with gout by the injection of MSU crystals into their femur-tibial tissue. Ethanolic extract of the aerial parts of Lychnophora pinaster and its main chemical constituents were evaluated as treatment. ResultsThe ethanolic extract and their main chemical constituents inhibited neutrophil migration, reduced IL-1β and TNF-α concentrations in the inflamed tissue and showed antinociceptive activity. ConclusionsGouty arthritis effects of the ethanolic extract can be attached to a synergistic effect of terpenes, flavonoids and phenolic acids present in the extract. Results obtained support the use of this extract and its main chemical constituents in the treatment of gout, inflammation, and pain.

Estimating Deformation Modulus and Bearing Capacity of Deep Soils from Dynamic Penetration Test

The dynamic penetration test (DPT) and the Menard pressuremeter test (PMT) have been widely used in geotechnical survey of deep soils for megadam foundations in western China. The DPT measures are not well utilized due to the lack of correction factors and of empirical relationships for deep soils. This study investigates the relationships between the corrected DPT blow counts ( N 120 ′ ), pressuremeter modulus (EPMT), limit pressure (pL), deformation modulus (E0), and bearing capacity (fak) derived from the PMT results. Meanwhile, a nonlinear regression model is developed to predict the DPT correction factor (a) based on the raw DPT blow counts (N120) and the rod length (L) by integrating the available correction factors for shallow gravelly soils suggested by the code provisions and the deep soil data in this work. It is concluded that the proposed DPT correction factors match well with the code suggestions and the new compiled dataset, and the corrected DPT blow counts can be used to reasonably predict the engineering properties of deep sand and clay soils. Although the proposed correlations need to be tested among different soil types and regions, the results shed the light on in situ geotechnical tests and data utilization for deep and thick overburden.

Application of in situ tests in unsaturated soils to analysis of spread footings

Spread footings are often supported in the upper zone of the soil profile, which is frequently unsaturated. It is common in geotechnical practice to use in situ testing to assess soil properties throughout the zone of influence for footings. These tests regularly include the Standard Penetration Test (SPT), and sometimes the Cone Penetration Test (CPT), and Pre-bored Pressuremeter Test (PMT). Yet degree of saturation is often not considered in the analysis of the test results. To investigate the importance of partial saturation, SPTs, CPTs, and PMTs were conducted at two test sites over two years covering dry and wet periods. Water content and suction profiles were established for each test date to assess their impact on the in situ tests. Results from this study revealed that changes in moisture content and suction had an important influence on the results of in situ tests and the soil parameters derived from these tests. Specifically, undrained shear strengths estimated from SPT penetration resistance and CPT tip resistance using empirical and semi-empirical equations, respectively, were significantly lower during wet periods compared to dry periods. Consequently, estimated bearing capacities for a shallow foundation varied considerably from dry to wet periods. Similarly, PMT limit pressures were significantly impacted by increases in moisture content. Associated reductions in limit pressures resulted in large reductions in predicted allowable bearing capacity. While PMT modulus did appear to decrease with increasing moisture, its impact on settlement was offset by the decrease in allowable bearing pressure under wet conditions.

CORRELATION BETWEEN SPT AND PMT RESULTS FOR SANDY AND CLAYEY SOILS

Determination of soil deformation and strength properties is of great importance in geotechnical design. The disturbance that occurred during the sampling from the field affects the results obtained by the laboratory tests. Therefore, the lack of representation of the field conditions and in-situ soil features with laboratory tests leads the designers to carry out field tests. Standard penetration test (SPT) and the Menard pressuremeter test (PMT) are the most widely used geotechnical field tests in which the results are utilized to investigate soil properties and lateral deformation characteristics at a specified depth. In this study, a total of 102 data of sandy and clayey soils belonging to the geotechnical investigations carried out in Istanbul were compiled. The regression analysis between the corrected SPT blow count N60, pressuremeter modulus EPMT, limit pressure PL and EPMT/PL ratio is performed. Empirical equations were separately developed for sandy and clayey soils between the considered parameters. The developed equations showed that there are acceptable relationships between the parameters examined in the particular dataset. Moreover, a neural network (NN) based prediction model was developed to predict EPMT and PL using the available soil data. The highly accurate prediction performance of the proposed model demonstrated the availability of modern methods for the estimation of soil parameters.

Comparison between pressuremeter modulus (EPMT) and shear wave velocity (Vs) in silty clay soil

Pressuremeter Test (PMT) and shear wave velocity (Vs) are two important in-situ tests for determining soil deformation characteristics in different strain levels. The PMT is an expensive and time-consuming test that can measure pressuremeter modulus (EPMT) of soil and rock. The Vs is a low-cost test for determining soil deformation through the seismic method. So finding the relationship between PMT and Vs can be useful and cost-saving for cross-checking the parameters obtained by these two methods.In this study, 94 PMT and Vs tests were carried out on silty clay and clay soil from 3 sites in Iran, and the relationship between EPMT and Vs was investigated using regression analysis. Finally, the best statistical model for relationships was proposed according to the highest value of adjusted R2 and Fisher coefficient (F) and a minimum value of significance (Sig.). The results showed that there is a direct relationship between EPMT, Vs, and N60 with depth then the soils with higher relative density are at the deeper layers. On the other hand, there is a linear significant relationship between EPMT and Vs for each site with R2 > 0.79. When the data for all three sites are considered together, R2 decreased to 0.62 but the overall trend of the data is similar. Due to the similarity of the soil of the three sites in terms of classification, minor differences in plasticity index and water content ranges in the three sites can be a reason to reduce the R2. The comparison between estimated EPMT based on proposed equations in the present study and measured EPMT shows that the normalized consistency ratio is generally close to zero (−0.09 < CR < 0.06) so the equations are valid and reliable.A comparison of the results of the present and a previous study showed that the change rates of EPMT and VS were similar so that the CR values are generally close to zero (−0.09 < CR < 0.09). The minor difference between the EPMT and Vs in each site in the present study and the previous research is due to the soil type and plasticity specifications.

Uncertainty quantification of in situ horizontal stress with pressuremeter using a statistical inverse analysis method

Knowledge of in situ stress magnitude and orientation plays a very important role in geological/geotechnical engineering and in the development of energy resources, such as caprock integrity, waste fluid disposal, geological storage of CO2, and geothermal energy extraction. The uncertainty of estimated parameters, especially horizontal stress, from in situ tests such as pressuremeter tests is a long-standing challenge owing to the existence of uncertainties from geomaterial spatial variability, measurement errors, limited information, and modelling methods. Therefore, non-unique solutions are often encountered in pressuremeter interpretation. In this study, a statistical inverse analysis method is proposed to solve this issue by combining a closed-form solution, finite-difference model, and selected optimization algorithms. The objective of the statistical inverse analysis is to determine the optimal parameters by minimizing the sum of squared errors while providing the confidence intervals of inversed parameters. Random variables generated in the optimization process reproduce the potential parameter uncertainties. The Jacobian matrix and confidence intervals are derived from the optimization process to evaluate variability of the predicted horizontal stress and ground properties. A workflow is presented that demonstrates a statistical inverse method for analyzing pressuremeter results and helps quantify uncertainties of the ground properties and in situ stress magnitudes and orientations derived from a pressuremeter test.

Laboratory Evaluation of the Measuring Capabilities of an Innovative Pressuremeter Probe in Dry Sand

Abstract This article presents the experimental procedures performed in a laboratory to evaluate the measuring capabilities of an innovative monocellular pressuremeter probe. This probe takes advantage of recent technological developments in the domain of inflatable membranes currently applied in the so-called Francis Cour standard tricellular probes, which allow covering an expansion range up to large cavity strains. Those improvements were found to enable increasing the accuracy in the assessment of radial expansion through volume injection in the probe measuring cell at relatively small strain levels without the need of sophisticated punctual measuring arms. Assessing this domain via in situ tests makes up a major contribution to the design of geotechnical structures under cyclic loads, for which the current design practice is mainly developed through laboratory soil tests. To reach this final objective, the probe’s validation program was launched based on pressuremeter tests with unload-reload loops performed in a laboratory calibration chamber and in situ on reference testing sites. This paper focuses on the laboratory testing protocols performed in dry Fontainebleau sand specimens. Shear moduli obtained with the pressuremeter are compared with the expected elementary values for this sand, and it is shown that it was possible to assess sand stiffness at a small strain level using this probe under controlled conditions in a laboratory.

Estimation of Pressuremeter Modulus and Limit Pressure in Weathered Granite Based on the SPT-N Value and Chemical Weathering Index: A Case Study in South Korea

A pressuremeter test (PMT) is a representative and highly reliable in situ test for assessing the stress–strain behavior of weathered granite. Its application, however, is restricted by its cost and time requirements. Many researchers have also investigated the correlations between the SPT-N value and the pressuremeter modulus (Em) and limit pressure (PL) of soils, but they have mostly focused on sand, silt, and clay and have employed simple regression analysis. In this study, equations for Em and PL were derived for weathered granite through multiple nonlinear regression analyses using a chemical weathering index that quantitatively represents the degree of weathering. Nonlinear multiple regression analyses were conducted by combining the allometric models that produced the optimal correlations between Em, PL, energy corrected SPT-N (SPT-N60), and normalized VR (Vogt’ ratio) with vertical effective stress. The obtained equations for Em and PL had higher R2 values (0.76 and 0.46, respectively) compared with the simple regression equations reported in previous studies. Because local characteristics are important determinants of the engineering properties of geo-materials, the Em and PL equations proposed in this paper are intended for use in geotechnical surveys of weathered granite in South Korea.

Maximising the efficiency of Menard pressuremeter testing in cohesive materials by a cookie-cutter drilling technique

Menard pressuremeter testing has been widely used in geotechnical engineering applications for 40 years and is an important technique in determining in-situ horizontal stress distributions. In this study, Menard pressuremeter testing is combined with a “cookie-cutter” insertion technique to determine horizontal stresses for a soft-rock in an operational Australian mine. The method presents an alternative to the Self-Bored Pressuremeter, with cookie-cutter drill rods allowing for sample recovery and further laboratory testing. The method accommodates for the presence of gravel and hard layered materials that present a risk of damage to cutting shoes of Self-Bored Pressuremeter devices. The combination of a sonic drill rig, coupled with the cookie cutter rods produces a close tolerance pocket resulting in “pseudo self boring pressuremeter tests”. The undrained shear strength, unload-reload shear modulus and in-situ horizontal stress are presented from pressuremeter tests conducted in the region for the first time. The undrained shear strength was observed in the range of 0.47–0.57 MPa, the unload-reload shear modulus between 17.43 and 18.25 MPa, the lift-off pressure in the range of 0.35–0.61 MPa. The K0 of coal was equal to 1, with interseam materials ranging from 2.1 to 3.5. Results of the cookie-cutter insertion method are compared with conventional drilling methods, with the cookie-cutter insertion test providing results in good agreement with both advanced triaxial laboratory tests and FEM numerical analysis. Cookie-cutter pressuremeter tests were conducted on cohesive soils at Australia's second-largest open-pit mine, with pressuremeter test results presented for Victorian brown coal for the first time.

Pressuremeter test in unsaturated soils: a numerical study

The paper presents a numerical analysis of pressuremeter test in unsaturated cohesive soils. In practice, pressuremeter is commonly expanded up to 10–15% cavity strains. At these strains, limit pressure is not usually reached, and its value is estimated by extrapolation. Accordingly, authors suggest using cavity pressure at 10% strain (P10) for the interpretation of pressuremeter test rather than limit pressure. At this strain, it is also assured that plastic strain occurs around the cavity, which is crucial for the interpretations. In unsaturated soils, the moisture at which a soil is tested has a noticeable influence on the pressuremeter cavity pressure, and consequently, on the magnitude of P10. In this paper, unsaturated soil behaviour has been captured by Barcelona basic model (BBM), and the influence of each BBM parameter on the P10 value is explored. Next, relative weight analysis technique is performed to investigate the relative importance of BBM parameters in prediction of P10. Artificial intelligence technique of genetic programming is used to develop a relationship to predict the P10 value in unsaturated soils from BBM parameters. Finally, the application of the proposed equation is shown through illustrative examples.

Coupling hardening soil model and Ménard pressuremeter tests to predict pile behavior

This paper presents a simple method to apply the Ménard Pressuremeter Test (PMT) results for the calibration of the soil stiffness due to primary deviatoric loading used in the Hardening Soil (HS) Model. A hyperbolic extension is used to rebuild the PMT pressure-expansion curve at small-strain values. The method was applied to simulate a series of PMT tests using axisymmetric finite element analysis (FEA) and was compared with the conventional HS model calibration using consolidated drained triaxial tests with reasonable accordance. Finally, the method was used in axisymmetric FEA of two static load tests in instrumented piles, performed in different sites. The results indicate good agreement between predicted and measured values of pile load-settlement behavior, average shear stresses at pile shaft and pile base pressure considering usual pile working loads. For highly mobilized piles, the numerical simulations indicated that an increase in soil cohesion was able to match the predictions of pile failure, in order to consider in a simplified way the effects of soil suction and pile execution procedure, which were not simulated herein.

An elastoplastic solution to undrained expansion of a cylindrical cavity in SANICLAY under plane stress condition

Although cylindrical cavity expansion under plane stress condition is commonly encountered in geotechnical problems, most currently available solutions have been developed for cavity expansion under plane strain condition. This paper develops a novel elastoplastic solution for undrained expansion of a cylindrical cavity in SANICLAY under plane stress condition. The SANICLAY model, which could well represent the mechanical behaviour of the anisotropic soil and overconsolidated soil, is employed in the present solution to model the responses of the soil around the expanded cavity. The problem is formulated as a system of first-order differential equations with the unknown variables as the functions of an auxiliary coordinate, which are solved as an initial value problem. The expansion responses under plane stress condition are comprehensively compared with those under plane stress condition to highlight the unique expansion responses under plane stress condition. The results show that the present solution could well reflect the unique expansion responses under plane stress condition, which are totally different from those under plane strain condition. It is expected the proposed solution could provide a reasonable approach to interpret the pressuremeter test and model pile installation effects near the surface of the natural anisotropic clays.

Relationship between Chemical Weathering Indices and Shear Strength of Highly and Completely Weathered Granite in South Korea

In South Korea, weathered granite is widely distributed and has been used as a bearing stratum for various structures. Therefore, it is important to determine the shear strength of the weathered granite. However, it is difficult to obtain reliable shear strength parameters with laboratory tests or standard penetration test (SPT) because weathered granite is easily crushed during the sampling process, and the penetrability of SPT is not secured. On the other hand, it is well known that weathering affects the variation of geotechnical properties. Based on this concept, this study reports a correlation between the shear strength parameters and the chemical weathering indices of the weathered granite. In this study, the pressuremeter test (PMT) was adopted to determine the friction angle of the weathered granite. For the identical granite, the chemical weathering indices (Vogt’s Ratio (VR), Chemical Index of Alteration (CIA), and Mobiles Index (Imob)) were measured by X-ray fluorescence (XRF). An estimating model considering both site-specific characteristics and degree of weathering was used, and the CIA showed the best correlation (R2 = 0.66) with friction angle among the weathering indices. Since the ratio of measured friction angle over the predicted one was distributed in the range from 0.8 to 1.2, it is more reasonable to predict friction angles based on CIA comparing to using the SPT-N value. It can contribute to a better estimation of friction angles of weathered granite.

Prediction of limit pressure and pressuremeter modulus using artificial neural network analysis based on CPTU data

Pressuremeter test (PMT) is conducted to obtain effective soil parameters such as limit pressure (PL) and pressuremeter modulus (Ep) that are frequently used in calculating foundation bearing capacity, settlement, and foundation behavior. However, the application of PMT in China was limited due to higher cost and time. There is a need for identifying a suitable method and establish models to predict reliable PL and Ep for interpreting or cross-checking soil parameters. Piezocone test (CPTU) offers an ideal test method to develop correlation models since it is widely adopted for geotechnical investigations in China. In this study, artificial neural networks (ANN) have been used to develop CPTU-PMT correlations. A total of 92 sets of sandy soil and 65 sets of clayey soil data from four testing sites were collected using CPTU and PMT. ANN was employed to develop 4 models, half of them considering effective overburden stress ( $$ {\sigma}_{v0}^{\hbox{'}} $$ ), for predicting PL and Ep from CPTU data. The obtained ANN models were validated using the measured values of PL and Ep from pressuremeter tests and also the predicted values based on previous correlations. The comparison results show that PL and Ep values predicted by ANN models proposed in this study are more consistent with the measured values at testing sites. Additionally, foundation settlements were measured from a load test and compared with predictive settlements obtained using PL and Ep estimated by the proposed ANN correlation models. The results have shown that the CPTU results can be used to accurately predict PMT parameters and derive settlements.

Experimental Geotechnical Characterization Campaign of the Matam Soil for Lithology: Application to the Study of Supports of the Balterdi Bridge

This paper presents a geotechnical study whose objective is to determine the lithology of the soil of Balterdi village (Matam, Senegal). A bridge-type structure with six supports is to be built on the studied site. The drilling program consisted of six core drillings (SC) each 30 m deep with sampling and six destructive drillings with pressuremeter tests (SP) every 1.5 m up to 30 m deep. A pair of core and pressuremeter tests was carried out under each support. From the results of the core drill holes and the geological model of the site, it can be seen that the lithology of the soil along the structure consists essentially of soft clay layers, becoming firm at depth over the first 18 m on average (with some incursions of sandy layers) resting on medium to compacted sand up to 30 m. Brown clayey fill is also present between piers P3 and P5. The presence of a watercourse along the structure is noted. The foundations will therefore be carried out in the water. The results of the pressuremeter tests confirm the homogeneity of the soil over the whole area. Indeed, the values obtained are almost similar for all the tests. According to the limit pressures obtained, the clayey-sandy formations encountered along the structure are respectively soft to firm and moderately compact to compact. Their limit pressures are high enough to allow good bearing capacities.

COMPUTATIONAL PROGRAM FOR EVALUATING PRESSUREMETER TEST RESULTS OF CLAY SOIL

Pressuremeters are often used in applications to test soils onsite; major developments for these devices are related to methods of manufacturing and analytical solutions to enable operation with different types of soils. In this study, pressuremeter tests were conducted in situ to obtain information on the horizontal at-rest pressure, elastic modulus, undrained shear strength, limit pressure, and horizontal coefficient of consolidation. Owing to the increasing importance of pressuremeter test results and their applicability in determining the engineering properties of soils, different methods and theories have been used to analyze and interpret pressuremeter parameters; many of the assumptions for these parameters reflect the uncertainties of soil properties: some assumptions are that the soil is elastic perfectly plastic and that the tests ensure plain strain conditions; furthermore, horizontal at-rest and limit pressures are critical to the design of foundations. A computational program was thus developed to explore the results of conventional and theoretical limit pressures using different analysis methods. This program was intended to simplify the methods used to determine the conventional and theoretical limit pressures without obtaining the curves necessary for determining the various parameters used in the conventional analysis; moreover, the program could unify the metrics used in the different analysis methods. Using the proposed program, the results of the conventional and theoretical limit pressures were shown to have distinct differences when using different analysis methods.

Assessment of soils liquefaction hazard on the Marchica lagoon zone, NE of Morocco

Liquefaction is a natural phenomenon that can occur in seismically active areas where the water table is shallower. This phenomenon mainly affects sandy soils rather than clayey soils. The assessment of the susceptibility to liquefaction is made on the basis of Kramer's four criteria. In addition, to evaluate the risk of liquefaction, we used the cyclic stress method, which is based on the comparison of the soil resistance to liquefaction (Cyclic Resistance Ratio, CRR) and the cyclic stress ratio (CSR) generated by the earthquake. A correlation between the Menard Pressuremeter Test and the Standard Penetration Test (SPT) is used to estimate CRR. Sand is the soil most sensitive to liquefaction due to its permeability and low cohesion. The result of the application of the cyclic stress method shows that the liquefaction potential is absent; this result is due to the consolidation of the sand at depth. The results of this work will alert the Marchica lagoon agency development to the imminent risk of liquefaction that will occur after the construction of infrastructure and buildings in the touristic project lands so-called “The city of two seas”.

Correlations Between SPT, PMT and MASW on Quaternary Alluvial - Fluvial Sediments in Battalgazi, Malatya, Turkey

The field tests such as the standard penetration test (SPT), pressuremeter test (PMT), and Multi-Channel Analysis of Surface Waves (MASW) give information about the stratigraphic properties, structure, underground water level, bearing capacity, and liquefaction of soil. The studies investigating the correlations between these tests are quite common. Most of the studies found in the literature have focused on sand, silty, and clay soils, while the number of the studies about gravelly soils is limited. In the study area, the gravel content ranged from 0% to 47% depending on local differences. Gravel sizes reached 80 mm at certain locations but remained below it in most locations. In this study, it has been discussed that how correlation studies will change in heterogeneous soils. Among the correlations between the field test results, with the highest R2 value of 0.6847, the strongest correlation was obtained between the PMT-PL value and SPT-N60 value, while, with a R2 value of 0.3906, the weakest correlation was between the PMT-Em value and MASW- Vs value. The low R2 values were attributed to the exceedingly heterogenous structure of the soil and locally changing gravel amounts.

Closed-form solutions for large strain analysis of cavity contraction in a bounded Mohr-Coulomb medium

This paper presents rigorous analytical solutions for cavity contraction analysis of a thick-walled cylinder/sphere after an arbitrary magnitude of expansion. Closed-form solutions are given for the distribution of stress and displacement within the cylinder/sphere of soil that is subjected to constant external pressure and monotonically decreasing internal pressure. The soil is modelled as an elastic-perfectly plastic material obeying the Mohr-Coulomb yield criterion and a non-associated flow rule. Large strain effects are taken into account by adopting the logarithmic strain definition in the plastic deformation analysis. The new solutions are validated with published results at first, then parametric studies are carried out. It is shown that the reference stress state (e.g. in-situ, elastic, partially plastic and fully plastic) and the cavity geometry ratio may greatly affect the unloading behaviour, in particular, when the cavity geometry ratio is smaller than a limit value. Finally, three typical applications of the solutions are demonstrated, including (i) design of the thickness of frozen cylinder walls accounting for large deformation effects, (ii) interpretation of laboratory pressuremeter tests with consideration of effect of the constant stress boundary, and (iii) shakedown analysis of a soil cylinder/sphere considering its geometry changes upon cyclic loading and unloading.

Expansion responses of a cylindrical cavity in overconsolidated unsaturated soils: A semi-analytical elastoplastic solution

This paper presents a semi-analytical elastoplastic solution for cylindrical cavity expansion in overconsolidated (OC) unsaturated soils under constant water content condition, in which both the OC features and the coupled hydro-mechanical behaviour of soils are properly addressed. The unified hardening model for OC unsaturated soil is further coupled with a void ratio-dependent soil-water characteristic curve to model the coupled hydro-mechanical soil responses during expansion. With the aid of an auxiliary variable, the coupled hydro-mechanical constitutive matrix for the investigated problem is finally formulated as a set of first-order ordinary differential equations in terms of Lagrangian description, with the three net stress components, the suction, and the void ratio as the basic unknowns. The governing differential equations are solved as an initial value problem with the code developed based on the Runge-Kutta algorithm. Parametric studies show that both the overconsolidation ratio and the suction have remarkable impacts on the expansion responses, including the distribution of stress components, the change of degree of saturation as well as the expansion pressures. The proposed solution could provide a reasonable tool for interpretation of the pressuremeter tests and prediction of pile installation effects in overconsolidated unsaturated soils.