Sand Silt Research Articles

Stress–strain Behavior of Silt Sand Soil Under Isotropically Consolidated Drained Conditions by Principal Stress Direction and Intermediate Stress Coefficient Parameters

Stress–strain Behavior of Silt Sand Soil Under Isotropically Consolidated Drained Conditions by Principal Stress Direction and Intermediate Stress Coefficient Parameters

Prediction of Excess Pore Water Pressure Generation in Sand–Silt Mixtures During Cyclic Loading: A Dissipated Energy-Based Model

Prediction of Excess Pore Water Pressure Generation in Sand–Silt Mixtures During Cyclic Loading: A Dissipated Energy-Based Model

Characteristics of Methane Hydrate Formation in a Gas–Water–Silt Sand Three-Phase Flow System and Its Effect on Multiphase Flow Behavior

Characteristics of Methane Hydrate Formation in a Gas–Water–Silt Sand Three-Phase Flow System and Its Effect on Multiphase Flow Behavior

A first report on the distribution of Ostracod taxa in the Ashtamudi Lake, southwest coast of Kerala, India

The present study is the first taxonomical account of Ostracoda occurring in the sediments of the Ashtamudi Lake in Kerala, intending to generate a baseline for future palaeo-ecological or palaeoenvironmental applications. A total of 22 Ostracod species belonging to 16 genera, 11 families, 5 superfamilies and 2 suborders of the order Podocopida have been identified from 66 surface sediment samples collected across the lake. Sedimentological parameters, such as CaCO3, organic matter, sand silt and clay, were estimated and their distribution is discussed. The ratio between the carapaces and open valves has been taken into consideration for determining the rate of sedimentation in the study area.

Influence of silt sand on the characteristics of methane hydrate equilibrium and formation

Influence of silt sand on the characteristics of methane hydrate equilibrium and formation

Role of Temperature-Dependent Interfacial Tension on Shear Wave Velocity for Energy Geosystems.

Interfacial tension varies with temperature. This paper investigates the effects of temperature-dependent interfacial tension on shear wave velocity. We designed a nylon cell equipped with bender elements in a cross-hole configuration to measure the shear wave velocity of nine sand-silt mixtures with different degrees of saturation (S = 0%, 2.5%, 5%, 10%, and 100%). All specimens were subjected to a temperature change from 10 °C to 1 °C. The results demonstrate that shear wave velocity tends to be very sensitive to changes in temperature at a low degree of saturation. Particle-scale analyses overlapped with the experimental results and captured the critical role of temperature-dependent interfacial tension in small-strain skeletal stiffness. In fact, the temperature should be considered during laboratory and field shear modulus measurements of the long-term performance of energy geosystems subjected to thermally induced repetitive loads.

Identifikasi Karakteristik Fisik Berbagai Jenis Agregat Halus dan Korelasinya pada Sifat Beton Segar dan Beton Padat

One of the main constituents of concrete is fine aggregate or sand. As a filler, the characteristics of sand affect the properties of both fresh and hardened concrete. The aim of this research is to identify the characteristics of various types of sand and to correlate them with the properties of the concrete. The type of sand used in the experiment is common type of sand used in construction; for instance, silt sand, river sand, and beach sand, as well as recycled sand from concrete waste. The examination on physical characteristics includes visualization with a digital microscope, specific gravity, water absorption, fine modulus, and impurities content. This characteristic is compared with the value of slump, concrete unit weight, and concrete compressive strength. Quarry sand has denser particles and a fairly coarse texture, while recycled sand has the finest, hollowest, lightest particles and a lighter color than other sands. According to the properties of fresh concrete, silt sand produces the lowest slump value while recycled sand has the highest slump value. A positive correlation in the form of y = 1,55x + C is obtained from the relationship of the specific gravity of sand (x) to the compressive strength of concrete (y) and constants (C). the same correlation but in a negative relationship is obtained from the influence of water absorption characteristics

Analysis Of Compressive Strength Of Foam Mortar With The Use Of Teratak Buluh Sand And Ringgit Sand

The core material in the manufacture of lightweight concrete (foam mortar) is influenced by the composition of the mixture of fine aggregate. The purpose of the study was to compare foam mortar with foaming agent using two types of fine aggregates from different sources, namely Teratak Buluh Sand, Kampar and Ringgit Sand, Indragiri Hulu. This study focuses on testing the properties of fine aggregate, flow value, bulk density and Unconfined Compression Strength (UCS) of foam mortar. The fine aggregate of Teratak Buluh has a mud content value of 0.50% while the ringgit sand silt content value is higher with a 1.92% mud content percentage value where the maximum silt content value is 3%. In this study, both types of aggregates had variations in the mixture of sand to cement, namely 18/82%; 16/84%; 15/85%; 14/86% and 12/88%. The flow value in a mixture of 14/86% Teratak Buluh Sand and a mixture of 12/88% ringgit sand has a flow value of 19.00 cm which is the highest value of the five variations. Teratak Buluh sand mixture of 14/86% has a higher value than the five variations, which is 781.67 Kg/m3 while ringgit sand has the highest density value of 758.12 Kg/m3 in a mixture of 12/88%. The value of Unconfined Compression Strength (UCS) using Teratak Buluh sand is superior when compared to the use of ringgit sand. The average value of the Unconfined Compression Strength (UCS) of lightweight foam mortar material from the use of mixed teratak buluh sand of 14/86% (1136.80 kPa) and 12/88% (1175.78 kPa) has the highest value which is close to the reference Unconfined Compression Strength (UCS) of the mixture. 15/85% (1253.73 kPa) while the mixture was 18/82%; 16/84% Teratak Buluh and 18/82%; 16/84%; 15/85%; 14/86%; 12/88% ringgit sand has the lowest f Unconfined Compression Strength (UCS) which does not meet the design Unconfined Compression Strength (UCS) of 1000 kPa and 800 kPa based on the SE-PUPR-46-SE-M-2015 specifications.

Effects of the Properties of Fines on the Pore Water Pressure Generation Characteristics of Sand–Silt–Clay Mixtures during Cyclic Loading

To investigate the effects of the properties of plastic fines on the pore water pressure generation characteristics of fine-grained soils during cyclic loadings, we used 29 sets of test data from the literature and prepared another 21 reconstituted specimens with different types of fines and fine contents (FCs) for cyclic triaxial testing. Two types of undisturbed soil specimens and three types of reconstituted soil specimens were also included for testing. The results indicated that under cyclic loading, the pore water pressure (PWP) ratios of clean sands increased slowly, stagnated, then finally accelerated until initial liquefaction, whereas those of the plastic soils containing fines with a plastic index (PI) value of >5 increased sharply in the initial stage. In addition, the cyclic stress ratio of specimens containing mudstone (PI = 12.4) and kaolinite (PI = 32.0) fines increased by 1.5–3.0 times more than non-plastic fines if the cyclic number chosen was 100. The range of the upper and lower limits of the PWP curves of the specimens with an FC of 30% were smaller that of the limits of the PWP curves of the specimens with an FC of 15%. The above results were further analyzed using a mathematical model. This paper systematically uses both the literature and laboratory test data to demonstrate that plastic fines and non-plastic fines have significantly different effects on water pressure generation under cyclic loading conditions, and a mathematical model also demonstrated the same trends. These findings are able to clarify previous unclear arguments. Thus, the model results developed in this study could also provide the field of engineering with a complete advanced calculation, requiring analysis only via software.

LAND SUBSIDENCE AND GEOTECHNICAL IMPACT OF JAKARTA KOTA AREA

Land subsidence has long occurred around the Special Capital Region of Jakarta. It is important to know and deal with Land subsidence events which also cause various negative impacts. Aim: When large amounts of groundwater are withdrawn from certain types of rocks, such as fine-grained sediments, land subsidence occurs. The rock compacts because the water helps to keep the ground in place. When the water is removed, the rocks collapse in on themselves.The immediate impact is the building collapse around the Kota Tua of DKI Jakarta. Methodology and Results: The research method used is a quantitative descriptive survey method by observing the amount of land subsidence that occurs in the Kota Tua area and its surroundings. The results showed that there has been a vertical land subsidence that varies between 20-60 cm. Based on the results of the resistivity values and coordinates plotted on the Regional Geological Map (Jakarta and Kep Seribu), the research location is classified into Lithology: Clay, Sand Silt, Gravel, and Pebbles (Quartenary deposits). The phenomenon, land subsidence, is caused by a combination of various parameters, including natural consolidation of alluvial soils, excessive groundwater extraction, and also building loads from infrastructure development and tectonic factors. Conclusion, significance, and impact study: Knowing the value of land subsidence and its location is expected to support urban planning, basic infrastructure planning and development, housing, settlement planning, and local financial improvement in efforts to mitigate land subsidence disasters.

Multidisciplinary Study of Mud Emissions Following the 2016 Norcia Earthquake

We report composition, grain size, and rheological data related to the mud emitted as a consequence of the maximum moment magnitude (Mw max = 6.5) on 30 October 2016, commonly referred to as the Norcia earthquake (central Italy), and on the activity of pre-existent mud volcanoes affected by the central Italy seismic sequence started on 24 August 2016. The emission sites were located at Monteleone di Fermo and Santa Vittoria in Matenano, two municipalities near the town of Fermo (Marche Region, Italy). We sampled, measured, and analyzed the products of mud emissions 3 days after the mainshock to characterize the mud by geochemical, mineralogical, and rheological analyses. The muds’ geochemical composition and low electrical conductivity suggest a continental origin, likely belonging to the Colombacci Formation. The collected muds are silt–sand–water-rich suspensions characterized by a Bigham rheology with viscosity values between 6.3∙107 and 6.9∙105 Pa∙s. The calculated minimum fluidization velocity of the mud suspensions is between 0.05 m/s (grain size of 2 μm) and 0.74 m/s (grain size of 8 μm). Water-rich mud suspensions flowing on a slope move faster as the water content increases up to 30 wt.%. At higher values, the velocity remains almost constant due to the disaggregation of bonds among the solid particles in the mixtures.

Effect of N Fertilizer Dosage and Base/Topdressing Ratio on Potato Growth Characteristics and Yield

Nitrogen fertilizer is an important kinetic energy for potato production. To study the effect of nitrogen(N) fertilizer application and the topdressing ratio on potato growth and yield, different N application levels: N75 (75 kg ha−1), N150 (150 kg ha−1), N225 (225 kg ha−1) and different N fertilizer base/topdressing ratios: T1 (2:8), T2 (5:5), T3 (8:2), and T4 (10:0) were used to find the best N fertilizer operation. The results showed that higher yields can be obtained when 120–180 kg ha−1 N was applied under the base/topdressing ratio of 8:2 in silt loam (sand–silt–clay: 29-50-21). The base N fertilizer dosage largely determined the root morphology, while topdressing fertilizer mainly affected the leaf photosystem, however, rhizosphere topdressing at the early stages of bud emergence did not immediately affect the leaf soluble protein and the sugar content. Topdressing N increased the tuber crude protein and ascorbic acid content to some extent, but had weak effect on the amylose/amylopectin ratio, for the starch content was mainly influenced by total N application. When base N fertilizer was low, it could be compensated by applying fertilizer during flowering, though when the amount of base fertilizer was sufficient, topdressing would cause a decrease in the average single potato weight and an increase in potato sets per plant, thereby reducing the commercial potato rate. Overall, adopting a suitable base/topdressing ratio can promote plant growth and improve tuber quality and yield. However, the relationship between the specific application amount and the ratio under different soil texture conditions needs further study.

IDENTIFIKASI KUALITAS CADANGAN AIR TANAH DI KECAMATAN SEKARAN KABUPATEN LAMONGAN

Groundwater is part of the hydrological cycle located below the earth's surface in the pores and crevices of rocks and soil. Water scarcity is increasing around the world and the need for water presence is increasing due to growing demands in several fields. Geologically, Sekaran District is composed of alluvium formations where this formation consists of kerakal, gravel, silt sand, clay, local fragments of fossil shells and mud. This study was conducted to determine the quality of groundwater reserves based on the value of solute solids. The method carried out by taking water samples in the wells of residents' houses in Sekaran District.After data processing was carried out, it was found that the quality of groundwater reserves based on the value of dissolved materials in Sekaran District ranged from 50-950 ppm and based on electrical conductivity values ranging from 100-2000 ?S/cm.

Particle size distribution effects on cavitation erosion in sediment suspensions

Synergistic cavitation–particle erosion often occurs in high-speed sediment-laden flow in hydraulic structures and machines. However, erosion prediction is challenging due to the unclear relationship between erosion and the characteristics of sand- and silt-sized sediments, particularly the sediment particle size distribution (PSDS). In this study, vibratory erosion tests for carbon steel were conducted in suspensions of continuously graded sand–silt mixtures, and the influence of PSDS characteristics, such as the number of modes and sand-to-silt ratios, was investigated. The results indicated that both the total sediment concentration and PSDS parameters had a major impact on synergistic erosion. The changes in the PSDS patterns resulted in different erosion behaviors, even when the sand and silt concentrations were fixed. Based on the viscosity-enhancing effects of silt particles and the impinging effects of sand particles, a new theoretical model for determining the particle impact energy was developed by incorporating PSDS. A deeper understanding of the influence of PSDS and the application of the PSDS-based model can help predict and prevent synergistic erosion.

Factors Affecting Small-Strain Shear Modulus of Sand–Silt Mixture Considering Different Moisture Contents

Factors Affecting Small-Strain Shear Modulus of Sand–Silt Mixture Considering Different Moisture Contents

Ground Improvement - Selected Tunisian Case Histories

This paper presents a detailed analysis of three Tunisian ground improvement case histories. The first case focuses on the cause of disorders that seriously affected the stability of an oil tank, initially built on a superficial soft clay layer improved by sand piles. Due to the underestimated length of sand piles, the oil tank operations stopped after non-admissible consolidation differential settlement. Retrofit solution using micropiles’ reinforcement revealed quite satisfactory to restart the functioning of the oil tank after fifteen years. The second case deals with the reinforcement of compressible silt sand layer by floating stone columns to reduce the long-term differential settlement of a gas storage facility. Recorded measurements during the follow-up of stage construction of the storage facility permitted the assessment of numerical predictions of the settlement of reinforced soil. The third case studies the stability of access ramps of an interchange in Tunis Centre. Built numerical plan strain modelling helped for the prediction of the behaviour of embankment access on improved Tunis soft soil by geodrains. Based on recorded settlements and horizontal displacements, followed the validation of computed consolidation settlement. Adoption of suitable parameters of hardening and soft soil modelling of the behaviour of Tunis soft clay is discussed.

The Study of Liquefied Soil by Using Swedish Weight Sounding Test in Jono Oge Village, Sigi Regency

The liquefaction that occurred on September 28, 2018, caused a massive lateral spreading in certain areas. This study aims to determine and compare the properties of land affected and not affected by liquefaction based on the Swedish Weight Sounding test, as well as the potential for liquefaction at Jono Oge village. The results of this study indicate that the laboratory test results show that the dominant soil classification on the affected and the unaffected soil is poorly graded sand silt (SP-SM). Whereas the results of field testing showed that the Nsw value on the affected soil is in the range 3,33 n/m – 263,16 n/m, the Nsw value on the unaffected soil is in the range 10,00n/m – 357,14 n/m, the qa value on the affected land is in the range up to 240,53 kN/m2, the qa value on the unaffected land is in the range of up to 315,71 kN/m2, the qu value on the affected land is in the range of 2.25 kN/m2 – 247,37 kN/m2, the qu value of unaffected land is in the range of 2.25 kN/m2 – 312,86 kN/m2.

Korelasi Air Entry Value (AEV) Dengan Kuat Geser Tanah Jenuh Sebagian

The characteristics of unsaturated soil seen from the Groundwater Characteristics Curve (SWCC). One of main variables determine the SWCC of soil are Air Entry Value (AEV). The AEV is the initial point of air entering the soil void. SWCC was obtained from the fitting of unsaturated soil model from Soil Vision. Although statistically a fitting model can match the point of laboratory result, the AEV resulted different point from the curve shaped by laboratory points. Therefore, this study aims to understand further the influence of AEV on unsaturated particularly on the change of soil share strength parameters. This studi used field investigation, a series of laboratory and numerical analysis to obtain Fredlund bimodal and Van Genutchen fitting model. Both models, then used to calculate the shear strength parameter (φ’, c’) change affected by different water content. On the other hand, the AEV consider as the major aspect on the calculation. The result shows that Van Genutchen model demonstrated the higher similarity with the laboratory test shear strength test comparing to Fredlund Bmodal’s. for silt sand oil in this study. This study is applicable for back filled and landslide case.

Study on the Erosion of Choke Valves in High-Pressure, High-Temperature Gas Wells

During the process of gas production in high-pressure, high-temperature (HPHT) gas wells, the choke valve, as the most vital component of the surface control equipment, plays a significant role in regulating the output and reducing the fluid pressure to ensure the safety of surface gathering and transportation equipment. High-pressure, high-velocity fluid flow and solid-phase particles cause deterioration of the choke valve. With the enhancement of intelligent and digital oilfields, conventional choke valves have been progressively replaced by electric choke valves. Due to the complex structure of the throttle valve, the flow path and the velocity state of the fluid in the throttle valve, and the distribution law of the erosion fraction are quite distinctive from those in the ordinary throttle valve, meriting further research. In this paper, a simulation of computational fluid dynamics (CFD) was conducted to determine the effects of the pressure distribution, fluid state, divergent particle sizes, and sand volume on the erosion rate of the choke valve. Under various valve openings, the fluid state and the location of high-risk points can be ascertained. The large particle size (diameter greater than 6 mm) of sand and gravel is convenient for causing concentrated erosion in the position of the valve hole, which induces the channel diameter to expand. Fine silt sand (diameter from 0.1 mm to 1 mm) gives rise to relatively uniform abrasion to the choke’s current-facing surface. This study can optimize the layout of the choke valve and reduce the cost and number of switching wells, thereby decreasing the frequency of maintenance and the pressure fluctuation’s effect on the formation.

Shear Modulus of a Carbonate Sand–Silt Mixture with THF Hydrate

The maximum shear modulus (Gmax) is an important factor determining soil deformation, and it is closely related to engineering safety and seafloor stability. In this study, a series of bender element tests was carried out to investigate the Gmax of a hydrate-bearing carbonate sand (CS)–silt mixture. The soil mixture adopted a CS:silt ratio of 1:4 by weight to mimic the fine-grained deposit of the South China Sea (SCS). Tetrahydrofuran (THF) was used to form the hydrate. Special specimen preparation procedures were adopted to form THF hydrate inside the intraparticle voids of the CS. The test results indicate that hydrate contributed to a significant part of the skeletal stiffness of the hydrate-bearing CS–silt mixture, and its Gmax at 5% hydrate saturation (Sh) was 4–6 times that of the host soil mixture. Such stiffness enhancement at a low Sh may be related to the cementation hydrate morphology. However, the Gmax of the hydrate-bearing CS–silt mixture was also sensitive to the effective stress for an Sh ranging between 5% and 31%, implying that the frame-supporting hydrate morphology also plays a key role in the skeletal stiffness of the soil mixture. Neither the existing cementation models nor the theoretical frame-supporting (i.e., Biot–Gassmann theory by Lee (BGTL)), could alone provide a satisfactory prediction of the test results. Thus, further theoretical study involving a combination of cementation and frame-supporting models is essential to understand the effects of complicated hydrate morphologies on the stiffness of soil with a substantial amount of intraparticle voids.