Hydraulic Conductivity Tests Research Articles

An appraisal of lateritic soil modified with lime and bamboo leaf ash as hydraulic barrier

The production of ashes from plant residue requires less energy and their application in construction industry would serve as a measure to reduce the over-reliance on the use of conventional stabilizing materials, which their means of production has negative influence on the environment, and also provides eco-friendly means of disposing such residue. This study investigates the influence of combined use of lime and bamboo leaf ash for the modification of lateritic soil as a construction material for hydraulic barrier in waste containment facilities. Natural soil was modified by adding BLA at percentage of 0%, 2%, 4%, 6%, 8% and lime at 1% 2% and 3% by weight of soil sample. Classification, compaction, volumetric shrinkage, unconfined compressive strength (UCS), hydraulic conductivity tests and microstructural analyses were carried out on both natural and stabilized soil. Results indicated that the natural soil was an A-7 and MH (sandy elastic silt) soil based on AASHTO and USCS classification respectively. The maximum dry density of natural soil increase from 1421 kg/m3 at natural state to the maximum of 1866 kg/m3, while the optimum moisture content decreased from 19% at natural to the minimum of 11.12% at 3% lime and 4% BLA addition. The volumetric shrinkage reduced from 7% at natural state to 3.58% at 3% lime-6% BLA addition and hydraulic conductivity also reduced from 5.36 × 10−5cm/s at natural state to 1.01 × 10−8cm/s at 3% lime-6% BLA. The UCS values increased from 390 kN/m2 at natural state to a maximum value of 754 kN/m2 at 3% lime 4% BLA mix, but later declined with further addition of BLA. The microstructural analyses showed that modified soil exhibited some densely packed particles than the natural soil. Based on the findings in the course of this study, addition of lime-BLA to the soil exhibited adequate strength and enhanced the soil and has a promising prospect for stabilization of lateritic soil as a construction material for hydraulic barrier in waste containment facilities.

Geomechanical aspects of stabilizing arsenic trioxide roaster waste in cemented paste backfill at the Giant Mine, Canada

Giant Mine, an abandoned gold mine near Yellowknife in the Northwest Territories of Canada, generated significant arsenic trioxide roaster waste (ATRW) during its operations, posing a substantial environmental hazard. This study explored the feasibility of stabilizing ATRW by incorporating it into cemented paste backfill (CPB). Using response surface methodology (RSM), CPB samples with varying mixing ratios were analyzed to identify key parameters influencing strength. Unconfined compressive strength (UCS) tests assessed physical stability, while saturated hydraulic conductivity and computed tomography (CT) analyses examined the microstructure of the CPB. The results revealed that CPB samples prepared with general use (GU) cement exhibited significantly higher strength than those with a GU and lime kiln dust (LKD) mixture. Binder and solid contents were identified as the most critical factors influencing UCS, with binder content having a more pronounced influence. Curing time was found to be non-significant. Higher binder and solid contents correlated with higher UCS values in the CPB samples. The addition of 10% wt. ATRW reduced the UCS by over 30%, particularly in samples with lower binder and solid contents. Although microstructure differences were not evident in saturated hydraulic conductivity tests, CT scans showed increased formation of high-density arsenic-containing materials in samples with the highest UCS, especially those using GU binder. These findings suggest that optimizing binder and solid contents is crucial for enhancing CPB strength and effectively stabilizing ATRW.

Geoenvironmental performance of nanogeopolymer-modified natural soil: Towards sustainable geocomposite liner application

The inevitable desiccation crack and excessive swelling of expansive clays have necessitated optimizing clayey soils for leachate retention and long-term performance in the landfill. Most clays are not suitable for compacted clay liner (CCL) use. To improve these substandard clay materials against heavy metals contamination and leachate permeation into the substrate soil. A moderate alkali solution of sodium silicate/sodium hydroxide (alkaline activator ratio: 0.5) concentration of 10 M and nanosized slag was used to build a nano-geopolymer (NGP). The synthesis of NGP was achieved by blending the alkali solution with varying percentages of nano slag (5 %, 10 %, 15 %, and 20 %). The developed NGP was used to modify the CCLs, followed by experimental testing. The fabricated CCL specimens were subjected to a series of pH tests, cation exchange capacity tests (CEC.), compaction tests, swelling pressure tests, unconfined compressive strength (UCS) tests, hydraulic conductivity (HC) tests, and desiccation crack tests through a digital image analyzer to evaluate the geotechnical performance of the NGP treated CCL. The results revealed an average of 83 % increase in strength. Meanwhile, the surface crack area ratio decreased to 28 % upon 20 % inclusion of NGP content. On the other hand, as the percentages of NGP increased, the swelling pressure decreased from 550 kPa to 130 kPa while the hydraulic conductivity decreased from 2.6×10−8m/s to 2.1×10−10m/s, suggesting an improved clay liner with greater retention capacity. Furthermore, with 20 % of nano-geopolymer content, the composite liner met the required standards for liner construction, including hydraulic conductivity <10−9 m/s and UCS (0.9 MPa > 0.2 MPa). Including NGP in CCL significantly improved the geotechnical properties of natural in-situ soil, making the investigated natural soil a suitable baseliner for leachate retention in landfills.

Anisotropic hydraulic conductivity of as-compacted, bare and vegetated soils

Soils are generally considered anisotropic with respect to hydraulic conductivity, while the evolution of the anisotropy condition is unknown for bare and vegetated soils. Therefore, the main goal of this study is to compare the anisotropic hydraulic conductivity of as-compacted, bare and vegetated specimens. Accordingly, a series of 54 hydraulic conductivity tests was conducted in a custom-made cube triaxial permeameter. The as-compacted specimens were revealed as isotropic because the loosely packed preparation procedure resulted in a dominant flocculent structure. However, a five-fold increase in the anisotropy ratio of bare specimens was measured along the isotropic loading path because of the induced surficial degradation zone formed by irrigation and desiccation processes, as evident in preliminary observations and crack network analysis. The variations in anisotropy ratio compared against void ratio function of vegetated soil generally fall below the corresponding function of the bare soil. The function was revealed to have a crossed nature, varying from sub-isotropic to super-isotropic states, corresponding to the lower and upper bounds of 0·3 and 3, respectively. It was postulated that vegetation impacts the flow differently by reducing the potential of desiccation cracks, creating preferential flow through the propagation of primary roots and clogging flow channels by secondary roots.

Oxidation effectiveness and kinetics of potassium permanganate on low-permeability phenanthrene-contaminated soil under fracturing conditions

For low-permeability contaminated sites, existing combined fracturing-oxidation remediation technologies rely on diffusive migration of the oxidant to remediate only a small area near the fracture, resulting in long site-wide remediation times. Therefore, this study proposed a new fracturing-enhanced oxidative remediation method aimed at achieving rapid remediation of low-permeability polycyclic aromatic hydrocarbon-contaminated sites. Specifically, this study investigated the effect of potassium permanganate (KMnO4) oxidation on the remediation time, total oxidant demand, phenanthrene (PHE) removal, oxidation kinetics, and physicochemical properties of low-permeability PHE-contaminated soil under fracturing conditions through one-dimensional rigid-wall hydraulic conductivity tests and a series of laboratory experiments. The results indicate that according to systematic evaluation, the optimal Darcy velocity was ≥ 5.95 × 10-6 m/s, and the optimal KMnO4 concentrations for remediation of contaminated soils with low and medium–high PHE concentrations were 1 g/L and 2 g/L, respectively. The migration of KMnO4 within the soil matrix between two adjacent parallel fractures followed piecewise first-order reaction kinetics. Additionally, KMnO4 oxidation under fracturing conditions had less impact on the physicochemical properties of low-permeability PHE-contaminated soils while significantly reducing their ecotoxicity. Overall, this new remediation method shows promise for the rapid and efficient cleanup of low-permeability contaminated sites. Further research is warranted to evaluate the influence of other factors (e.g., permeability) on the oxidation effectiveness and kinetics of KMnO4 in low-permeability PHE-contaminated soils.

Influence of steel slag content on the mechanical and hydraulic properties of compacted silt-bentonite mixtures

ABSTRACT The reuse of by-products has become increasingly important as a means of minimising the consumption of natural resources and reducing waste disposal. This study examines the potential reuse of steel slag for soil stabilisation, with benefits such as conserving natural resources and mitigating the greenhouse gas emissions associated with the production of conventional stabilising agents. It focuses on evaluating the effect of pozzolanic reactions on the strength and stiffness of both loess silt and silt-bentonite mixtures. The experimental tests included the physical characterisation of granular materials, reactivity tests of the pozzolanicity of soil mixtures, compaction tests, unconfined compression tests, and hydraulic conductivity tests. The impact of the curing period was also analysed to quantify the effects of natural cementation and the development of hydrogels within soil pores on the compacted soil properties. The findings suggest that adding steel slag can significantly increase the strength and the stiffness of compacted loess silts by over 300% and 500%, respectively, after 56 days of curing, substantially reducing the hydraulic conductivity of granular materials, such as the tested silt, as hydrogels partially occupy the pores available for liquid flow. It should be noted that the chemical reactions during hydrogel formation may hinder the free expansion of clay mixtures and release Ca2+ ions, thereby counteracting the expected reduction in hydraulic conductivity when bentonite is added to compacted earthen barriers.

RELIABILITY OF GUELPH PERMEAMETER FOR DETERMINING THE LINERS HYDRAULIC CONDUCTIVITY

The aim of this study is to evaluate whether the Guelph permeameter can be effectively used as a quick and reliable instrument to measure the hydraulic conductivity of compacted mineral liners. The investigation was carried out on two distinct areas of the final capping of a municipal solid waste landfill in Italy. On the first test site, hydraulic conductivity tests were performed using the Guelph permeameter, assessing reliability and repeatability of test results. On the second one, many undisturbed soil samples were taken and tested in the laboratory using a modified oedometric apparatus as a falling-head permeameter. Further hydraulic conductivity tests with Guelph permeameter were also performed in the holes made by soil sampling. The campaign was integrated with in situ density tests using the calibrated sand method, to check the uniformity of the compaction degree of liners. A final comparison between hydraulic conductivity obtained in situ and in the laboratory was proposed and critically analysed. The experiments performed on the two test sites with the Guelph permeameter and their statistical processing demonstrate that the instrument is not only economical and easy to use, but also reliable if used with appropriate precautions.

Density spatial distribution and anisotropy of full-scale bentonite-sand blocks

Constructing buffer barriers using high-quality bentonite-based blocks is crucial for the secure disposal of high-level radioactive waste (HLW). However, the density distribution and anisotropy of full-size bentonite-sand blocks are not yet fully understood, which may affect their quality and performance as buffer barriers. This study aimed to address this critical issue by conducting computed tomography (CT) scanning tests on full-size bentonite-sand blocks in the radial, angular, and vertical directions to obtain CT numbers and density. The analysis of the density distribution and anisotropy in these three directions followed. Subsequently, thermal conductivity and hydraulic conductivity tests were conducted in these directions to explore their relationship with density anisotropy. The findings revealed that the block density gradually decreased with increasing radius in the radial direction and first decreased slightly and then increased slightly in the angular and vertical directions. However, the density of the bentonite-sand mixture inside the blocks ranged from 1.96 g/cm³ to 2.09 g/cm³, with minimal differences. Additionally, there was no significant difference in density between the radial and angular directions, with an average density of 2.06 g/cm³. The density in the vertical direction was slightly lower, with an average density of 2.04 g/cm³. Scanning electron microscope images validated the presence of anisotropy in block density caused by horizontally oriented bentonite aggregates resulting from axial compression. However, the presence of quartz sand and incompressible impurities in the blocks created preferential flow paths, mitigating the impact of block density anisotropy on thermal and hydraulic conductivity. Consequently, thermal conductivity, averaging 1.60 W/m·K, and hydraulic conductivity, averaging 3.12 × 10−10 cm/s, demonstrated isotropy in all three directions. These block parameters meet the design requirements for an effective buffer barrier. This study systematically reveals the density distribution of full-size bentonite-sand blocks and its impact on the performance, providing important references for the safe design of HLW repositories.

Hydraulic conductivity of bentonite–polymer geosynthetic clay liners subject to wet–dry cycles used in landfill cover systems

This study evaluated the hydraulic conductivity of bentonite–polymer (B-P) geosynthetic clay liners (GCLs) subjected to wet-dry cycles that simulated seasonal conditions on a GCL installed in a landfill cover system. Hydraulic conductivity tests were conducted on B-P GCLs and NaB GCLs at 10 kPa in accordance with the ASTM D5084 standard. Two wet–dry methods were used to investigate the hydraulic conductivity of the GCLs under different field exposure conditions. The hydraulic conductivities of the NaB and B-P GCLs gradually increased during four wet–dry cycles. However, the hydraulic conductivity of the B-P GCL (K = 2.3 × 10-12 m/s) was lower than that of the NaB GCL (K = 6.3 × 10-11 m/s) by two orders of magnitude after four permeation–drying cycles. In addition, the hydraulic conductivity of the B-P GCL was lower (K = 5.8 × 10-12 m/s) than that of the NaB GCL (K = 7.8 × 10-10 m/s) by two orders of magnitude after four saturation–drying cycles. The results suggest that B-P GCLs can enhance the effectiveness of landfill cover systems compared to Na-B GCLs in managing conditions during wet and dry seasons.

Long-term hydraulic conductivity of bentonite-polymer geosynthetic clay liners

Hydraulic conductivity tests were conducted on six bentonite-polymer (B–P) geosynthetic clay liners (GCLs) to investigate the effect of the slow cation exchange process and polymer elution on the long-term hydraulic conductivity of B–P GCLs. Tests were conducted up to 1458 days and as many as 443 pore volumes of flows (PVFs). Three B–P GCLs consist of linear polymer whereas the other three have crosslinked polymer. One sodium geosynthetic clay liner (Na–B GCL) was used as a control. Hydraulic conductivities (K6766) of B–P GCLs (5.4 × 10−12 m/s to 3.7 × 10−11 m/s) per ASTM D6766 were approximately 2-3 orders of magnitude lower than that of Na–B GCL (2.3 × 10−9 m/s to 3.5 × 10−9 m/s). Tests were continued after hydraulic and chemical equilibrium to investigate the long-term hydraulic conductivity of GCLs. Hydraulic conductivities of GCLs had an increasing trend after hydraulic and chemical equilibrium. The ratio of KL/K6766 for B–P GCLs was 3.5–14.7, whereas ratio of KL/K6766 for Na–B GCLs was 1.0–1.7. Total organic carbon (TOC) tests results confirmed that polymer elution occurred during the entire permeation process. The higher ratio of KL/K6766 for B–P GCLs was attributed to the effect of polymer elution.

Understanding the creep behavior of bentonite-sand mixtures as buffer materials in a low-level radioactive waste repository in Taiwan

This study investigates the creep behavior of bentonite-sand mixtures as potential buffer materials for low-level radioactive waste (LLW) repositories, with a specific case study in Taiwan. To assess the long-term hydro-mechanical properties, constant-volume swelling pressure, hydraulic conductivity, strain-controlled shear, and stress-controlled shear tests were conducted on MX80 and KV1 bentonite-sand mixtures. The experimental results indicate that MX80-sand 70/30 mixtures are prioritized as the buffer materials with 2.10 MPa swelling pressure and 1 × 10−13 m/s hydraulic conductivity. However, the shear strength of mixtures was reduced by almost 50 % when fully saturated. Furthermore, this study proposed a novel stress-controlled direct shear apparatus to retrieve the creep model parameters. The numerical method based on the creep model efficiently supports and simulates the saturation process and creep displacement. The finite element method (FEM) result predicts that the buffer of both bentonite-sand mixtures will achieve an average degree of saturation of 95 % at the end of three decades and full saturation in 100 years. The simulated creep displacement results at key nodes suggest that both top and bottom parts in the buffer, assembled from MX80-sand 70/30 mixtures or KV1-sand 70/30 mixtures, will have almost equivalent values of 4 mm in the horizontal and 2 mm in the vertical directions eventually.

Mineralogy and geotechnical properties of alkaline-activated kaolin with zeolitic tuff and cement kiln dust as landfill liners

Mixtures of variable proportions of kaolin, quartz sand, zeolitic tuff, and cement kiln dust were blended while adding an 8 M sodium hydroxide (NaOH) solution to allow alkali-activation of kaolin and achieve the optimum strength. This study investigated the mineralogy, microstructure, and geotechnical properties of the prepared mixtures. The aim was to produce a sustainable, environmentally friendly landfill liner. The samples were compacted in stainless steel molds to a maximum dry density and optimum moisture content, extruded from the molds, and left to cure in an oven at varying temperatures from 40°C to 80°C for 24 h. The investigations included XRD, SEM, unconfined compressive strength, and hydraulic conductivity tests. Test results showed the development of a hydroxysodalite binder due to the alkali reaction of kaolin, which caused an increase in strength ranging from 20 to 25 MPa depending on the curing temperature. Alkaline activation was effective even at temperatures as low as 40°C. A mixture of 100 units of kaolin, 45 units of sand, 45 units of zeolitic tuff, and 10% by weight cement kiln dust (CKD) with an 8 M sodium hydroxide activator was found to best achieve the required strength and hydraulic conductivity of 10−9 m/s for the landfill liner. The zeolitic tuff with high cation exchange capacity, available in the mixture, absorbs contaminants in the leachate and prevents pollution of the groundwater. The use of cement kiln dust contributes to enhancing strength and solving an acute environmental problem.

Modification of bentonite with black cotton soil and carboxyl methyl cellulose for the enhancement of hydraulic performance of geosynthetic clay liners

ABSTRACT Geosynthetic clay liners (GCLs) are mostly used as flow barriers in landfills and waste containments due to their low hydraulic conductivity to prevent the leachate from reaching the environment. The self-healing and swell-shrink properties of soft clays (expansive soils) such as bentonite enable them as promising materials for the GCL core layers. However, it is important to modify their physico-chemical properties in order to overcome the functional limitations of GCL under different hydraulic conditions. In the present study, locally available black cotton soil (BCS) is introduced in the presence of an anionic polymer named carboxymethyl cellulose (CMC) as an alternative to bentonite to enhance the hydraulic properties of GCL under different compositions. The modified GCL is prepared by stitching the liner with an optimum percentage of CMC along with various percentages of BCS mixed with bentonite. Hydraulic conductivity tests were performed on the modified GCL using the flexi-wall permeameter. The results suggest that the lowest hydraulic conductivity of 4.58 × 10−10 m/s is obtained when 25% of BCS is blended with bentonite and an optimum 8% CMC and further addition of BCS results in the reduction of the hydraulic conductivity.

Effect of wet and dry cycles on lighter bentonite-polymer geosynthetic clay liners

This study evaluated the hydraulic conductivity (K) of lighter bentonitepolymer (B-P) geosynthetic clay liners (GCLs) subjected to wet-dry cycles which simulated seasonal conditions on a GCL installed in a landfill cover system. Lighter bentonite-polymer composite (B-P) GCLs are manufactured with a lower mass per unit area of sodium bentonite (Na-B) (approximately 2.9 kg/m2) than conventional Na-B GCLs (approximately ≥ 3.6 kg/m2) which can reduce the transportation and installation costs compared to conventional Na-B GCLs. Hydraulic conductivity tests on lighter B-P GCL and Na-B GCL were conducted with a synthetic soil porewater leachate to represent wet season conditions on a landfill cover. Between hydraulic conductivity tests, GCL samples were placed in sealed chambers with a relative humidity of 75% until the water content of the specimens decreased to 55%, which represented dry season conditions of a GCL under a geomembrane in a cover system. Slight increases of the hydraulic conductivity were measured for both the Na-B and lighter B-P GCLs. After 5 wet-dry cycles K of the Na-B GCL increased from 3.1 x 10-12 m/s to 8.3 x 10-12 m/s, and K of the lighter B-P GCL increased from 1.6 x 10-12 m/s to 8.3 x 10-12 m/s.

High Temperature Effect on the Engineering Performance of Pumice Added Sand-Bentonite Mixtures

The surrounding soils at energy geo-structures must perform for a long time under high temperatures and thermal cycles. Engineering properties of soils are affected by temperature. Pumice is a thermally durable material and it may be used to increase thermal durability of soils. For this reason, it was aimed to develop thermally durable soil material by adding pumice additive to sand-bentonite mixtures. 10% and 20% pumice were added to 10% and 20% sand-bentonite mixtures and compaction, consolidation, direct shear and hydraulic conductivity tests were performed. The direct shear and hydraulic conductivity tests were performed both at room temperature and 80 °C. The consolidation test results showed that as pumice content increases the total vertical deformation decreased at room temperature. Pumice additive reduced the maximum shear stress values when temperature increased for 10B-90S mixtures. However, the pumice additive increased the internal friction angle of the mixtures at high temperature. It was observed that the hydraulic conductivity increased with increasing temperature. Thermal conductivity measurements showed that pumice additive reduced the thermal conductivity value of the mixtures.

A systematic approach for conducting and interpreting hydraulic conductivity tests on granular soils under non-isothermal conditions

Although non-isothermal tests are important for many applications in geotechnical engineering, there is no standard for conducting such tests and interpreting the resulting data. This paper describes the development of a temperature-controlled triaxial apparatus, focussing on its thermal performance, and discusses relevant protocols to perform and interpret hydraulic conductivity tests on granular materials at different temperatures. With the aid of thermal cameras, hot spots on the surface of the equipment and instruments were identified. Subsequent modifications to minimise and mitigate heat reaching volume gauges and pore water pressure transducers were introduced. After modifications to reduce the system’s intrinsic head losses, the thermal expansion of the system proved to be significant and needed to be accounted for avoiding overestimation of thermally-induced mechanical strains. The addition of a new probe at the centre of the specimen allowed the characterisation of the temperature field within the system and specimen, as well as assisting with the identification of thermal equilibrium. Significant drops in temperature were flagged by this probe, though these proved to be unimportant in terms of hydraulic conductivity. The use of the average temperature for each pressure step is advised when a specimen probe is available. Alternatively, the use of target temperatures can be chosen, leading to minor underestimations of the intrinsic permeability.

GEOLOGY, SEDIMENTOLOGICAL AND HYDRAULIC CONDUCTIVITY OF AJALI POTENTIAL RESERVOIR SANDSTONE EXPOSED AROUND GRA IN IDAH, NORTHERN ANAMBRA BASIN

The Ajali sandstone is a possible reservoir rock in the Lower Benue Trough (LBT)/Anambra Basin (AB), and understanding its geological, sedimentological distribution is essential for accurate prediction of fluid flow dynamic. Geological, granulometric analysis and laboratory hydraulic conductivity test are integrated for this investigation. Results from geological studies reveals three sandstone lithofacies; namely; AJALI L2A a sandstone intermixed with siltstone, lamination, bioturbated, and crossed bedded, AJALI L2B sandstone mixed with silty clay, crossed bedded and bioturbated and AJALI L2C an excessive weathered sandstone with visible ripple and ridges with all sedimentary features supporting the earlier proposed fluvio-deltaic depositional environments. The granulometric analysis reveals medium to coarse grain, poorly sorted sandstone lithofacies. Hydraulic conductivity test for AJALI L2A crossed bedded and lamination sandstone contributes smaller pore spaces between grains, which reduce overall interconnectivity of the pore network primarily decreasing the fluid hydraulic flow conductivity and thus lowers the permeability value to 75mD. While in the AJALI L2B intermixed with siltstone and clay sandstone, lowers porosity; but cross-bedding may have contributed positively to increase in permeability value to 1850 mD in this lithofacies. The weathered AJALI L2C sandstone with visible ripples and ridges significantly affect the physical properties and pore spaces obliteration by iron oxide, by contributing to reduction in the permeability value to 60 mD. In overall it is concluded that the Ajali sandstones generally will exhibits an average moderate permeability of 662 mD.

A New Fracturing Method to Improve Stimulation Effect of Marl Tight Oil Reservoir in Sichuan Basin

China’s argillaceous limestone reservoir has a lot of oil and gas resources, and hydraulic fracturing of the argillaceous limestone reservoir faces many difficulties. The first problem is that the heterogeneity of the argillaceous limestone reservoir is strong, and it is difficult to optimize fracturing parameters. The second problem is that there are a lot of natural fractures in the argillaceous limestone reservoir, which leads to a lot of fracturing fluid loss. The third problem is that the closure pressure of the argillaceous limestone reservoir is high, and the conductivity of fractures decreases rapidly under high closure pressure. The last problem is that the fracture shape of the argillaceous limestone reservoir is complex, and the law of proppant migration is unclear. The main research methods in this paper include reservoir numerical simulation, fluid-loss-reducer performance evaluation, flow conductivity tests and proppant migration visualization. To solve the above problems, this paper establishes the fracturing productivity prediction model of complex lithology reservoirs and defines the optimal hydraulic fracturing parameters of the argillous limestone reservoir in the Sichuan Basin. The 70/140 mesh ceramide was selected as the fluid loss additive after an evaluation of the sealing properties of different mesh ceramides. At the same time, the hydraulic fracture conductivity test is carried out in this paper, and it is confirmed that the fracture conductivity of 70/140 mesh and 40/70 mesh composite particle-size ceramics mixed according to the mass ratio of 5:5 is the highest. When the closure pressure is 40 MPa, the conductivity of a mixture of 70/140 mesh ceramic and 40/70 mesh ceramic is 35.6% higher than that of a mixture of 70/140 mesh ceramic and 30/50 mesh ceramic. The proppant migration visualization device is used to evaluate the morphology of the sand dike formed by the ceramsite, and it is clear that the shape of the sand dike is the best when the mass ratio of 70/140 mesh ceramsite and 40/70 mesh ceramsite is 6:4. The research results achieved a good stimulation effect in the SC1 well. The daily oil production of the SC1 well is 20 t, and the monitoring results of the wide-area electromagnetic method show that the fracturing fracture length of the SC1 well is up to 129 m.

Soils hydraulic conductivity tests in slopes affected by fire: an example on Pisani Mountains (Tuscany, Italy)

Soils hydraulic conductivity tests in slopes affected by fire: an example on Pisani Mountains (Tuscany, Italy)

Assessment of a new rigid wall permeameter for the slurry like barrier materials: zeolite example

Areas vulnerable to catastrophic disasters such as hurricane, landslide and earthquake require ready and sustainable solutions for the post-pollution scenarios. Clinoptilolite type zeolite re- sources of Türkiye can serve economical and sustainable solutions as a quick response. While the studies on compacted zeolite-bentonite mixture at optimum water content for the landfill liners applications or dry zeolite-sand mixtures in permeable reactive barrier (PRB)s are com- mon, the slurry form of zeolite emplacement at subsurface reactive barriers has not received an attention by the researchers. In this context, this experimental study presents the prelimi- nary findings on one-dimensional consolidation and hydraulic conductivity tests performed on crushed zeolite samples S1 and S2 with fine contents of 33 and 84%, respectively. The results indicate that S2 has a higher compression index than S1, without a significant change in swelling index attributed to less than 4% clay contents. A self-designed rigid wall type per- meameter was used to study on reconstituted slurry like materials under the benefit of back pressure saturation without the consolidation during testing that encountered in flexible wall permeameter. Falling head – rising tail water procedure was adopted under the back pressure in between 200 and 700 kN/m2. S2 samples reconstituted under 25, 50, 100 and 200 kN/m2 show a gradual decrease in kv from 3×10-8 to 2×10-9 m/s. Previous observations on the sample of S1 revealed 8 times higher kv values under the same σv'. Since the fine content of zeolite limits kv, the proposed permeameter will be beneficial to determine the proper grain size dis- tribution of fill materials considering the barrier height and in-situ stress conditions before the environmental studies with leachate.