Sand Gravel Research Articles

Investigation of Backfill Compaction Effect on Buried Concrete Pipes

The present study deals with the experimental investigation of buried concrete pipes. Concrete pipes are buried in loose and dense conditions of gravelly sand soil and subjected to different surface loadings to study the effects of the backfill compaction on the pipe. The experimental investigation was accomplished using full-scale precast unreinforced concrete pipes with 300 mm internal diameter tested in a laboratory soil box test facility set up for this study. Two loading platforms are used namely, uniform loading platform and patch loading platform. The wheel load was simulated through patch loading platform which have dimensions of 254 mm *508 mm, which is used by AASHTO to model the wheel load of a HS20 truck. The pipe-soil systems were loaded up to pipes collapse. Pipes were instrumented with strain gauges to measure circumferential strains, in addition to dial gauges, for measurements of the pipe vertical deflections and settlement of the loading platforms. The test results indicated that flexure governed the buried pipe behavior. Flexural cracks formed slightly before the ultimate load. A comparison of soil backfill, between a loose and dense compaction, showed that the dense backfill improve largely the pipe installation and the strength ofpipe-soil system

Detection of groundwater aquifers using geoelectrical resistivity method (case study : Plupuh Sub-district, Sragen District )

An aquifer is a layer below the ground surface that contains groundwater. Inside the earth there are unconfined aquifers and confined aquifers, where unconfined aquifers are located near the surface while confined aquifers are located very deep beneath the earth. This study aims to find the location, depth, and thickness of aquifers that have the potential to contain large amounts of groundwater. The instrument used in this research is a resistivity meter OYO Model 2119C Mc OHM-EL, with a Schlumberger configuration with a current electrode length of AB/2 to 350 meters. Data acquisition were carried out in the Plupuh sub-district, Sragen district as many as 5 sounding points, and data processing using IP2win software. Based on the interpretation of resistivity geoelectrical data, it can be concluded that the area has the potential to have a lot of groundwater content, for unconfined aquifers at the TS1 sounding point with a depth of 7.7 meters to 19.2 meters with a thickness of 11.5 meters. and TS4 with a depth of 15.4 meters to 30 meters with a layer thickness of 14.6 meters. This aquifer layer is dominated by sand layer lithology, while the confined aquifer layer is located around TS1 and TS2. The two sounding points are located in the east and northeast of the research area. TS1 was detected at a depth of 39.9 meters to 110 meters with a layer thickness of 60.1 meters and TS2 was at a depth of 40.2 meters to 66.5 meters and 80.2 meters to 139.7 meters with a thickness of 84.8 meters. This aquifer layer is dominated by the gravel sand layer in TS1 and the sand layer in TS2.

Response of soil respiration to hydrothermal effects of gravel–sand mulch in arid regions of the Loess Plateau, China

Gravel–sand mulching is a traditional no–tillage technique used for more than 300 years on the Loess Plateau. Applying gravel–sand mulch (mixture of gravel and sand) has an impact on the soil environment, soil microorganisms, and crop yield. However, we know surprisingly little of how respiration dynamics at the soil surface is affected by gravel–sand mulching. To study the response of soil respiration (Rs) dynamics to different in gravel–sand mulch thickness and its driving factors, we recorded Rs under a gradient of gravel–sand mulch thickness consisting of six layers (0 cm [CK], 3 cm, 5 cm, 7 cm, 9 cm, 11 cm), in situ, during the growing season by using the LI–6400–09 soil respiration measurement system on the Loess Plateau in northwest China. The trends of all six treatments in diurnal and monthly variation of soil respiration followed a single–peaked curve; the diurnal dynamics trends were consistent with soil temperature changes. With gravel–sand mulch applied, the daily peak of soil respiration decreased, and the peak in Rs under the gravel–sand mulch treatments lagged that of bare land by 2 h. Monthly changes in soil respiration were consistent with soil temperature and precipitation changes, with peaks concentrated in July and August. Compared with bare land (CK), the monthly average soil respiration is lowest at 0.67 µmol∙m–2∙s–1 under a 11–cm thick mulch layer, and reduced by 26.63–61.03% by all mulch applications. Gravel–sand mulch reduced the temperature sensitivity of soil respiration, while soil temperature and soil water content were the main factors determining soil respiration. The thickness of gravel–sand has a significant, negative exponential function relationship with the changes in monthly soil respiration. Further, compared with bare land, the presence of gravel–sand mulch reduced the positive impact of precipitation on Rs. Soil temperature (T), gravel–sand mulch thickness (M), and soil pH were all significant predictors of soil respiration (Rs) (multiple regression model: Rs = 8.561 + 0.077 T – 0.056 M – 0.989 pH), together accounting for 73% of its variation. Hence, by considering all these three factors simultaneously we can better explain the changes to soil respiration in response to gravel–sand mulch. Overall, our results show that as the thickness of the gravel–sand layer increases, soil respiration decreases.

Compression responses and particle breakage of calcareous granular material in reclaimed islands

Calcareous gravelly sand (CGS) is a highly compressible and easily breakable granular geomaterial widely used to fill the island reef foundation. In this study, a series of confined compression tests were conducted on CGS, and the particle breakage of CGS was quantitatively assessed. The results showed that the power function model was more suitable for describing the stress-strain relationship of CGS under confined compression than the hyperbolic and Gunary models. The yield stress of CGS was distributed within the range of 1.89–2.45 MPa, which was significantly smaller than that of terrigenous quartz sand. The compression modulus of CGS increased with increasing relative density (Dr); however, it first increased and then decreased with increasing nonuniform coefficient (Cu). The compression behaviors of CGS after the yield point were mainly determined by particle breakage. The CGS sample, which had experienced more serious particle breakage, was compressed to a more compact state under vertical stress. The relative breakage ratio of CGS decreased with increasing Dr, whereas it first increased and then decreased with increasing Cu. The changes in the fractal dimension and gradation parameters of CGS before and after testing were also evaluated. The particle breakage mechanism of CGS during confined compression was revealed based on the changes in the mass fraction of different particle groups before and after testing.

Sedimentary architecture and glacial hydrodynamic significance of the stratified Oak Ridges Moraine, southern Ontario, Canada

High‐quality subsurface data provide new insights into the formation of Oak Ridges Moraine (ORM), an ~80 km3 sequence of stratified meltwater deposits resting >200 m above adjacent Lake Ontario. The ORM sedimentary succession comprises a three‐part regional architecture: (i) ~north–south channel sand–gravel; (ii) channel‐capping rhythmites; and (iii) east–west ridge sediments. The ORM depositional sequence overlies a regional unconformity with a cross‐cutting channel network resulting from ~north–south meltwater floods that transitioned progressively (falling stage) from a ~NNE to ENE flow direction (parallels Lake Ontario depression). Seismic profiles delineate the channels and channel fill characteristics of bank‐to‐bank channel sedimentation of thick gradational gravel–sand–mud sequences. Channel‐capping mud (~100–236 rhythmites) within multiple channels beneath the ORM landform mark a widespread interval of low‐energy, seasonally controlled subglacial pond deposition. During this quiescent period ice‐sheet thickness adjusted to flood‐induced stretching/thinning and re‐profiled slopes. New ice gradients led to east–west flow and deposition of the overlying third element, a sequence of high‐energy confined esker–fan sediments along ORM ridge. Close, sequential timing (~329 varve years) of channel, basin and ridge‐forming architectural elements supports naming this assemblage the ORM formation. Proposed ORM floods are analogous to Icelandic jökulhlaups based on the size, geometry and sedimentology. The observed rhythmite interval between flood events represents a short period (~236 years) of regional meltwater storage prior to east–west ORM flooding. The ORM channel and overlying esker‐fan sediment ridge represent two closely timed meltwater drainage events rather than formation by coalescing ice streams. The scale and timing of the ORM flood events are linked to rapid sea‐level rise, ~13.5 ka BP. This high‐resolution ORM sedimentological record may provide insights into depositional and glaciogenic controls of other large, stratified moraines. The ORM data indicate deposition in response to hydrodynamic events (outbreak floods, re‐profiled ice) rather than direct climate forcing.

Spatial distribution differences of cholinesterase in healthy Chinese under the influence of geographical environmental factors.

The main targets of this were to screen the factors that may influence the distribution of cholinesterase (CHE) reference value in healthy people, and further explored the geographical distribution differences of CHE reference value in China. In this study, we collected the CHE data of 17,601 healthy people from 173 cities in China to analyse the correlation between CHE and 22 geography secondary indexes through spearman regression analysis. Six indexes with significant correlation were extracted, and a ridge regression model was built, and the country's urban CHE reference value of healthy Chinese was predicted. By using the disjunctive kriging method, we obtained the geographical distribution of CHE reference values for healthy people in China. The reference value of CHE for healthy Chinese was significantly correlated with the 6 secondary indexes, namely, latitude (°), altitude (m), annual average temperature (°C), annual average relative humidity (%) and annual precipitation (mm), and topsoil sand gravel percentage (% wt). The geographical distribution of CHE values of healthy Chinese showed a trend of being higher in southeast China and lower in northwest. This study lays a foundation for further research on the mechanism of different influencing factors on the reference value of CHE index. A ridge regression model composed of significant influencing factors has been established to provide the basis for formulating reference criteria for the treatment factors of the liver damage diseases and livercancer using CHE reference values in different regions.

THE LITHOLOGY OF FLOOD PRONE AREAS USING THE VERTICAL ELECTRICAL SOUNDING (VES) METHOD

Rock lithology modeling of flood-prone areas has been carried out using the Vertical Electrical Sounding (VES) method in Rawa Makmur village, Bengkulu city. Field data acquisition using a stretch length of 160 with the MAE X612-EM Geoelectric tool forming a straight line. VES method, using Excel software for resistivity variations with depth and Progress lithology modeling. This research aims to determine the subsurface condition of flood-prone areas and the characteristics of rocks that make up flood-prone areas. The results of this study can be concluded that the Rawa Makmur village is dominated by sand (0,2-50 Ωm), silty sand (1-35 Ωm), gravel sand (20-150 Ωm) and clay (65-250 Ωm) at several points. VES 1, VES 2, VES 3, VES 4, VES 5, VES 8, and VES 9 have a shallow water table of 1-10 meters, close to the Rawa Makmur river and have a rock structure that is saturated with water so that it cannot absorb moisture on the surface and becomes a flood puddle. The characteristics of rocks that make up flood-prone areas are porous stones such as sand and gravel saturated with water. Sites that are not prone to flooding in the Rawa Makmur village at points VES 6 and VES 7 are dominated by the rock structure of sand (20-65 Ωm), gravel sand (100-200 Ωm), and dry gravel (100-1000 Ωm).

Internal erosion of debris-flow deposits triggered by seepage

Debris flows can be triggered by runoffs at considerably steep natural channels and streams. Specifically, runoff-generated debris-flow deposits are loose mixtures, comprising coarse and fine particles. Owing to seeping water, these fine particles are eroded and transported through the skeleton formed by the coarse particles. Such erosion can modify the porosity of deposits and influence their mechanical characteristics, which can be non-negligible for geotechnical and geological engineering. In this study, seven groups of seepage tests on gravel–sand–clay mixtures with different coarse particle content proportions (48%, 52%, 60%, 70%, 80%, 90%, and 100%) were conducted to investigate the erosion characteristics of debris-flow deposits triggered by seepage flows. In particular, concentrated leak erosion, internal instability erosion, and piping were noted in the soil with a coarse particle content of 48%–80%. Further, when the coarse particle content exceeds 80%, the soil does not disintegrate. A model coupling seepage and internal erosion was also developed to characterise internal erosion. For this model, mass conservation equations were reformulated for different types of internal erosion, based on the assumptions for the pore channel erosion of suspended materials and general erosion. Moreover, an equation based on the internal erosion rate, considering the pore size distribution and hydraulic gradient, was firstly introduced for concentrated leak and internal instability erosion. This equation could efficiently evaluate the mass of particles eroded from the soil. Lastly, the model was calibrated based on experimental data; the corresponding results are discussed herein.

Correction: Numerical simulation study on sand gravel layer collapse induced by tunnel lining damage

Correction: Numerical simulation study on sand gravel layer collapse induced by tunnel lining damage

Estimation of Stiffness of Non-Cohesive Soil in Natural State and Improved by Fiber and/or Cement Addition under Different Load Conditions

The aim of this study was to compare the stiffness of gravelly sand under various load conditions-static conditions using the CBR test and cyclic conditions using the resilient modulus test. The tests were conducted on natural soil and soil improved by the addition of polypropylene fibers and/or 1.5% cement. The impacts of the compaction and curing time of the stabilized samples were also determined. The soil was sheared during the Mr tests, even after fiber reinforcement, so the resilient modulus value for the unbound sand could not be obtained. The cement addition improved Mr, and the curing time also had an impact on this parameter. The fiber addition increased the value of the resilient modulus. The CBR value of the compacted gravelly sand was relatively high. It increased after adding 0.1% fibers in the case of the standard compacted samples. The greater fiber addition lowered the CBR value. For the modified compacted samples, each addition of fibers reduced the CBR value reduced the CBR value. The addition of cement influenced the CBR increase, which was also affected by the compaction method and the curing time. The addition of fibers to the stabilized sample improved the CBR value. The relationship Mr=f(CBR) obtained for all data sets was statistically significant but characterized by a large error of estimate.

The sedimentation and shoreline change on the coast of Tanjung Kapal Cape, Rupat Island

Tanjung Kapal is a cape area located on Rupat Island and is influenced by the oceanographic characteristics of the Rupat Strait. This research was conducted in June 2022 to provide information about the level of accretion on the coast of Tanjung Kapal from 2002 to 2020. The research was carried out through two steps : 1) processing of secondary data using Landsat Imagery Data, and 2) collection of sediment samples using a sediment grab, along with oceanographic observations (currents, tides, and waves) at the coast. Statistical calculations used to determine the accretion rate at Tanjung Kapal included EPR (End Point Rate) and NSM (Net Shoreline Movement), which are features of the DSAS (Digital Shoreline Analysis System). The results showed that the accretion rate on the coast of Tanjung Kapal ranged from 5.5 to 21.36 meters per year over the 18-year period. The waves at Tanjung Kapal have a height of 0.12 m with a period of 2 s, and current velocity of 0.16 m/s flowing towards the northwest. Accretion is thought to be due to a system of currents and waves flowing along the Tanjung Kapal beach, which carries sediment and then accumulates along the coast. Additionally, the coastal sediments, dominated by the gravel sand fraction with a sand percentage of 57.97%, are derived from the Rupat Strait by the current system.

Technical Study of Sediment Pond Maintenance Scheduling ( Sediment pond) For Guard Quality Sand Wash PT. Gunung Source Fortune

PT. Gunung Sumber Rejeki is a subsidiary of PT. Agung Satrya Abadi which is located at Wonosunyo Village, Kec. Gempol, Kab. Pasuruan, Province. East Java. Gravel sand mining The sale value of natural products (sirtu) can be increased by processing and refining. The feed material is brought to the stone crusher and sand washing plant with the production of stone split 1 cm – 1 cm, 1 cm – 2 cm, 5 cm – 10 cm and sand wash with a silt content of less than 5%. In 1 cycle of pond maintenance, the feed material that can be processed is 1587.15 tons with a maintenance schedule every 6 days in all pond segments. Sludge impurities from the process washing sand flowed into pond one and experienced as much sedimentation 298.5 m 3 /6 days, pool two as much 313.98 m3 / 6 day, pool three as much 365.7 m3 / 6 day, and pool four as much 385.5 m3 / 6 day. Maintenance settling pond very need done because water in a settling pond reused for washing sand so that very influential on quality sand which in earn

Geophysical and Geotechnical Evaluation of Landslide Slip Surface in a Residual Soil for Monitoring of Slope Instability

AbstractElectrical Resistivity Tomography (ERT) technique has been widely used conventionally to monitor slope instability; however, a detailed study to validate ERT models with geotechnical properties for monitoring of slope instability is still rare. The objective of this work was to evaluate soil water conditions in gravelly sand soil that influences slope instability. The ERT investigation was conducted on a 60 m survey length with 1.5 m electrodes space to obtain subsurface geological structures and geotechnical laboratory tests, and experiments were carried out to obtain soil engineering properties for validation of the ERT model results. Our results revealed three geological zones namely: saturated, weathered granite, boulders and floaters, and resistivity values of 1–800 Ωm, 1,200–4,000 Ωm, and >4,000 Ωm, respectively. The saturated zones were characterized by subsidence during dry season and possible collapsed structures of boulders and floaters during prolonged heavy rainfall. The analyzed ERT models revealed that the slip surface of a potential landslide may occur at the boundary between the saturated and weathered granite zones within 3.0 m depth. The analyzed geotechnical properties also confirmed the ERT result because the potential landslide sliding surface was delineated within 3.0 m depth at the boundary between gravelly sand with a lowest angle of internal friction of 30° and a cohesion of 8 KPa, which was easier to destroy, and silty sand with a high angle of internal friction of 33.8° and a cohesion of 12.7 KPa, which was more difficult to destroy. These findings are very fundamental in shaping the earth's surface, especially in the formation of landscapes.

Numerical simulation study on sand gravel layer collapse induced by tunnel lining damage

Numerical simulation study on sand gravel layer collapse induced by tunnel lining damage

Characteristics of Bottom Sediments in the Coastal Areas of the Crimean Peninsula

The aim of this work was to assess the influence of physical, chemical, and hydrochemical factors on the characteristics of bottom sediments in various areas of the shelf of the Crimean Peninsula. The data obtained during the cruises of the RV “Professor Vodianitsky” in the fall of 2018 and summer of 2019 were analyzed. Hydrochemical analyses of the bottom waters were carried out using standard hydrochemical methods. Profiles of dissolved oxygen, hydrogen sulfide, and oxidized and reduced forms of iron in pore waters were obtained, and the geochemical characteristics of bottom sediments were determined. The features of their spatial and vertical distributions were considered. Pelite-aleuritic sediments with inclusions of sandy material and shell detritus prevailed in the coastal zone of the Crimean shelf. The organic carbon content varied from 0.5–0.6% in the gravel–sand sediments of the Kerch pre-strait area to 2.5–2.7% in the northwestern part. The prevalence of suboxic conditions was noted, and the main processes in the sediment upper layer were controlled mainly by reactions involving iron. In some areas of the southern coast of Crimea and the Kerch pre-strait area from the Sea of Azov, the development of anoxic conditions in the surface layer of bottom sediments was recorded.

Hybrid 1D-CNN and attention-based Bi-GRU neural networks for predicting moisture content of sand gravel using NIR spectroscopy

A non-destructive and rapid moisture content detection method of sand gravel material is required in loose material dams. The near-infrared (NIR) spectrum of sand materials is closely related to its moisture content. Recently, there is a growing need for fully using spectral information when establishing calibration models for sand gravel moisture content detection. To address these issues, a hybrid one dimensional-convolutional neural network (1D-CNN) and attention-based bidirectional gated recurrent unit (Bi-GRU) neural network was proposed to detect sand gravel moisture content with NIR spectrum. Two learners, namely, 1D-CNN and Bi-GRU, were constructed to extract local abstract information and sequence position information from the spectrum, respectively. In the 1D-CNN learner, multiple kernels CNN layers and one dimensional-separable convolution layers were conjunct to improve model accuracy and reduce network parameters. In the Bi-GRU learner, a multi-head self-attention mechanism was appended to evaluate the weights of the output features extracted by Bi-GRU layers. The proposed model achieved the best prediction results in LUCAS dataset (R2 greater than 0.75, RPD greater than 2.0) and our sand gravel spectral dataset (R2 = 0.96, RPD = 5.06) compared to other deep learning and conventional spectroscopy analysis methods. In addition, the top ten characteristic wavelength points of sand gravel were identified. These can be used to choose a discrete spectrum measuring instrument, which has a relatively low cost.

Functional zoning optimization design of cemented sand and gravel dam based on modified Duncan-Chang nonlinear elastic model

Cemented sand and gravel is widely used in water conservancy project construction due to its advantages of low material consumption, strong adaptability and environmental protection. Due to the single design of the dam section, its application scope is limited. Aiming at the design problem of the cemented sand gravel dam section, In this paper, the modified Duncan-Chang nonlinear elastic model is used as the constitutive model of dam material, and the design concept of dam functional zoning is combined with the mechanical properties of Cemented sand and gravel dam material to propose the optimal design scheme of functional zoning in line with the CSG dam. The Tobetsu dam in Japan is used as a prototype for finite element optimization design analysis, and the analysis results are compared with the engineering data. The results show that: (1) The optimized scheme changes the upstream slope to 1:0.34 and the downstream slope to 1:0.77 under the condition of ensuring the safe operation of the dam, which reduces the amount of cementitious admixture per unit dam section by 34.2% and 23.6% respectively, significantly reducing the amount of cementitious materials used, in line with the concept of optimal design; (2) The vertical stress of the dam body is compressive stress during the completion period, but both during the operation period, the location of the dam heel appears; (3)The upstream side of the dam axis should have a large modulus of deformation during the operation period, and the modulus of deformation can be reduced from upstream to downstream in order to ensure that the dam deformation is coordinated after water storage.

Variation characteristics of water and sediment of managed aquifer recharge with the Yellow River water in the piedmont sand gravel channel in the North China Plain

Abstract A two-dimensional sand tank model was designed to investigate the water distribution and sediment clogging of the Yellow River water during the seepage recharge process of the piedmont sand gravel channel in the North China Plain. Due to the high permeability of the sand gravel medium, only infiltration deep runoff (IDR) and surface runoff (SR) occurred in the sand tank experiment. The increase in water released did not improve the effective recharge. The IDR accounted for 65–85% of the water released. After clogging appeared, the value decreased to 15–30%. More than 96% of suspended solids were deposited in the surface and upper areas of the sand tank, among which the sand gravel surface covered by the thin clay layer formed by suspended particles was the main cause of the change in the distribution of IDR and SR. A rubber dam can promote the conversion of high velocity SR to low velocity lateral shallow runoff (LSR) by 25–30% while increasing the deposition mass of suspended particles in the sand tank. The rationality of the sand tank model was verified by the numerical model, and the fitting degree between the simulated and the measured results was greater than 0.9.

Unsteady-State Conjugate Heat Transfer Model of Freeze-Sealing Pipe Roof Method and Sensitivity Analysis of Influencing Factors of Freezing Effect

The freeze-sealing pipe roof (FSPR) method has been applied to the Gongbei tunnel of the Hongkong–Zhuhai–Macau Bridge, which is the first application of this method in the world. The purpose of the ground-freezing method is soil waterproofing. Temperature is an important indicator for measuring the freezing effect; however, the FSPR method involves unsteady-state conjugate heat transfer between frozen soil, steel pipes, concrete, air, and other media. This paper proposes an unsteady-state conjugate heat transfer model and establishes a global solution algorithm of a strong coupling governing equation based on the virtual density method. Then, a calculation based on COMSOL software is realized and validated. The sensitivity of different factors such as initial formation temperature, different soil layers, and brine temperature on the freezing effect was studied by simulating the FSPR model. It is concluded that the brine temperature had a greater impact on the freezing effect, followed by the soil layer, whereas the formation temperature had the least impact. For muddy silty clay, if the brine temperature is −20 °C, it takes 44 days to meet the design requirements of 2 m. If the brine temperature is −30 °C, 27 days is enough. When the formation temperature is 20 °C, it takes 20 days for medium gravel sand to reach the thickness of the freezing curtain, and 32 days for muddy silty clay. Compared to other soil layers, the freezing effect of the medium gravel sand is relatively better. This research has a certain impetus to similar multimedia freezing heat transfer issues.

Elastoplastic Constitutive Model of Sand–Gravel Composites Considering the Whole Shearing Process

Elastoplastic Constitutive Model of Sand–Gravel Composites Considering the Whole Shearing Process