Gravel Layer Research Articles

Effects of Vegetation and Saturated Zone in Cascaded Bioretention on Enhancing Nutrient Removal

Bioretention is a water management practice that is increasingly being applied for runoff quality control. Although previous Bioretention studies have used some techniques to improve nutrient removal, some nutrients still leach out. Therefore, this study used Cascaded Bioretention (CB) by connecting three Bioretention columns in series. The planted Bioretention Column was retrofitted by adding a subsurface drainage module (SDM) below the gravel layer to create a dual saturated zone. This study aimed to investigate the effect of the number of treatments, vegetation, and modified saturated zone on enhancing nutrient removal from agricultural runoff and to understand nutrient removal mechanisms. The removal efficiencies of NH3-N, NO3-N, NO2-N, and TN improved to 89.8%, 49.7%, 49.2%, and 53.4%, respectively. The only negative removal was ON, which significantly decreased by incorporating vegetation and a modified saturated zone. Increasing the number of treatments significantly enhanced TN and ON while maintaining stable removal for other nitrogen compounds. However, phosphorus was less sensitive to increasing the number of treatments. Nitrogen removal could be enhanced by different removal processes such as nitrification, denitrification, mineralization, assimilation by plant uptake, and Anammox. However, phosphorus removal was less complicated, as adsorption and infiltration are likely to be the main removal mechanisms.

Effect of hydraulic conductivity and impeded drainage on the liquefaction potential of gravelly soils

Investigating the role of sand and fines content and in situ drainage conditions in governing the hydraulic conductivity of gravelly deposits is highly important to characterize the liquefaction potential of gravelly soil. In this study, a variation of hydraulic conductivity with sand content has been empirically obtained based on the existing gravel liquefaction case histories. It is found that the hydraulic conductivity of a soil matrix having more than about 20%–30% sand content by mass is low enough to cause liquefaction without the presence of any impervious confining layer. In addition, a numerical study has been performed using the commercial software FEQDrain to study pore pressure generation in gravelly soil at a variety of relative densities and hydraulic conductivities with and without an impermeable cap layer when subjected to a variety of earthquake loadings. For both unconfined and confined condition, excess pore pressure ratios consistently increase with a decrease in hydraulic conductivity ( k) and relative density ( Dr). Excess pore pressure ratio is correlated with hydraulic conductivity, soil compressibility, and cyclic stress ratio (CSR). For the confined condition, pore pressure in the gravel layer is primarily governed by the overlying cap layer and even a sandy cap layer instead of highly impervious clay layer can cause liquefaction.

Significance of fluvial landform evolution and river reorganization in settlement development over the past 50 ka: A case study of Baodun site on Chengdu Plain, SW China

The Baodun archaeological site, which is representative of Baodun Culture (4.5–3.6 cal. ka BP), is a well-known walled site covering large areas of the Chengdu Plain (CDP), which is located in the upper reaches of the Yangtze River. The CDP is a low-lying sedimentary basin that is one of the cradles of Chinese civilization and was formed by many rivers originating from the northeastern part of the Qinghai–Tibetan Plateau. Geological and hydrological characteristics have strongly influenced the development of ancient cultures on the CDP. However, their relationship has not been validated. Based on field investigations, ground surveys, microgeomorphological discrimination, grain-size measurements, tree species identification, and the analysis of fluvial deposits, including age dating, height measurement, and observations of gravel layers, we investigated the effects of geomorphology and river channel migration on the evolution of the Baodun site. The results showed that three grades of terraces developed at the Baodun site region during the past ~50 ka BP, which had important impacts on the regional evolution of geomorphology and river systems. The chronology constrains the ages of terraces T1, T2, and T3 to ~7, ~22, and ~48 ka, respectively; T2 and T3 were closely related to tectonic activity, whereas T1 was related to climate variation. Similar to the modern river system, ancient waterflow primarily originated from the northwest; however, it mixed with water from other directions in the past. We attribute the construction of the Baodun site to the persistently outcropped terraces and the attraction of more stable rivers, which provided space and resources for the Baodun people. The evolution of the river system influenced the safety of the Baodun site, and flooding was the main factor leading to its decline and abandonment. The stability of the terrace and sedimentary environments and the decreased precipitation were important factors influencing the large-scale habitation of archaeological sites on the CDP during the middle and late Holocene.

Morphodynamic evolution of paraglacial spit complexes on a tide-influenced Arctic fjord delta (Dicksonfjorden, Svalbard)

Recent global warming triggered pronounced geomorphic changes such as coastal retreat and delta progradation along the coastlines of the Arctic regions. Coastal morphodynamics and associated sediment transport at the Arctic fjord head remain relatively unexplored due to the logistically limited accessibility to the field area, especially at short-term temporal scales. A repeat survey using an unmanned aerial vehicle (UAV)-assisted photogrammetry was conducted to quantify the annual morphodynamics of gravel spit complexes developed on the tidal delta plain of the deglaciated Dicksonfjorden, Svalbard of Arctic. Results show that the spit morphodynamics varies in time and space with an overall downfjord increase in the growth and migration rate of the spits. The youngest spits elongated 22 m yr−1 and migrated landward 4.3 m yr−1 between 2015 and 2019, marking the most pronounced spit morphodynamics documented to date in the Svalbard fjord systems. The spit morphodynamics is driven primarily by longshore drift and to a lesser degree by overwash processes. Gravels constituting the spits originate from the unconsolidated debris-flow deposits of old alluvial fans, which locally retreat 0.5 m yr−1. The growth of the spit complexes is also fed by snow meltwater discharge on the alluvial fans, accounting for a downfjord imbrication of angular gravel layers that are intercalated with interlaminated sands and muds on the landward sides of the spits. The breached spits at the most upfjord location have remained stationary during the study period and presumably since the 1930s. Rapid delta progradation combined with an isostatic rebound after the Little Ice Age (LIA) has decreased spit morphodynamics on the tidal delta plain upfjord in Dicksonfjorden with infrequent and insignificant wave influence. Sparse distribution of the isolated spits signifies the intermittent spit development, which is constrained by the proximity to the protruded alluvial fans. The spit complexes in Dicksonfjorden highlight that climate change accelerates coastal geomorphic changes at the fjord head by enhancing wave intensity and regulating episodic sediment delivery that led to the downfjord shift in the locus of wave shoaling.

Deep and ultra-deep oil and gas well drilling technologies: Progress and prospect

In the period of “13th Five-Year Plan”, domestic deep and ultra-deep oil/gas well drilling technologies were developed quickly and a great number of technological achievements were obtained by means of continuous researches, including: (1) high-end devices, such as automatic drilling rig, managed pressure drilling, logging, cementing and completion technology, high-torque top drive system, and deep-well coiled tubing operation unit; (2) advanced tools, such as vertical drilling tool, non-planar tooth bit, high-strength expandable tubular, high-temperature, high-torque and long-life screw rod, torsion impact tool, synergistic damping based rock breaking tool, measurement while drilling tool, and safety monitoring tool; (3) core additives, such as temperature-resistance high-density oil based drilling fluid, high-performance water based drilling fluid, ductile cement slurry, and self-healing cement slurry; (4) life-cycle wellbore integrity technology system. Nevertheless, oil and gas well drilling and completion still faces severe challenges, including deep (great burial depth), steep (large formation dip), narrow (narrow pressure window), thick (thick gravel layer, salt bed and other complex intervals), difficult (complex multi-pressure system, abundant complex accidents and poor drillability) and high (high temperature, high pressure and high acid). Facing these challenges, the following suggestions are proposed. The key to the oil and gas reserve and production increase during the 14th Five-Year Plan and afterwards is till deep and ultra-deep layers. And it is necessary to focus on above mentioned geological difficulties to research key core technologies, such as automatic and intelligent drilling equipment, ultra-high temperature wellbore working fluid, pre-exploration while drilling and digital twin well construction, so as to realize the iterative upgrading of traditional superior technologies and improve the ability to drill deep and ultra-deep wells safely, quickly and optimally. In conclusion, during the 13th Five-Year Plan, China exceeded America in the number of ultra-deep wells for the first time and its well depth stepped up to a new stage of 8000 m, which plays an important role in supporting the development of deep oil and gas exploration and development and improving the market competitiveness of drilling and completion.

PENGGUNAAN METODE GEOLISTRIK RESISTIVITAS KONFIGURASI SCHLUMBERGER UNTUK MENGETAHUI LAPISAN STRUKTUR LITOLOGI BAWAH TANAH DI TAMAN ILMU UNIVERSITAS RIAU

Research has been carried out at the Science Park, Riau University to determine the layers of underground lithological structures using the one-dimensional Schlumberger configuration Geoelectric resistivity method. Research data processing is done using Software Progress. The results of data processing show that lanes 1 and 2 consists of layers of alluvium, sand, gravel, and clay. On track 1, the highest soil layer resistivity value of 863.14 m is interpreted as a layer of sand and gravel at a depth of 2.28 - 31.12 m, while the smallest is 226.90 m which can be interpreted as a layer of clay at a depth of 0.68 - 1.28 m. On track 2, the highest soil layer resistivity value of 1027.83 m is interpreted as a layer of sand and gravel at a depth of 0.28 - 1.15 m, while the smallest is 188.08 m interpreted as a clay layer at a depth of 0 - 0.28 m. The highest and lowest resistivity values tend to be identified as sand, gravel, and clay, respectively.

Isochron 26Al/10Be burial dating of the Xiashagou Fauna in the Nihewan Basin, northern China: Implications for biogeography and early hominin dispersals

The Nihewan Basin in northern China is one of the most dense occurrences of Early Pleistocene vertebrate paleontological and Paleolithic sites outside of Africa and thus plays a key role in the study of biochronostratigraphy and early human evolution in East Asia. The Xiashagou Fauna, as the first systematically studied fauna in the basin, is usually referred to as the Nihewan Fauna (sensu stricto) and is considered the Early Pleistocene type fauna in northern China, serving as a key reference for biostratigraphical correlations. The Xiashagou Fauna was initially correlated with the Olivola Fauna of early Late Villafranchian age in Europe, dated to ∼1.8 Ma. It has been more recently constrained to the Matuyama chron between the Réunion and Olduvai subchrons, with an estimated age range of 2.2–1.7 Ma. However, there is still an absence of absolute dates associated with this important Fauna. Here, the isochron 26Al/10Be burial dating method was used to radio-isotopically verify the biostratigraphic and magnetostratigraphic age of the Xiashagou Fauna. Two sets of quartzose clasts were collected from the cross-sections near Xiashagou. The isochron burial age of six samples from one of the fossil-bearing layers is 2.05 ± 0.38 (0.39) Ma (bracketed uncertainty includes external systematic errors, ±1σ), in agreement with previous paleomagnetic estimates of 2.2–1.7 Ma. The isochron age of another five samples from a gravel layer about 80 m below the sampled fossil layer and 55 m beneath the deepest buried fossil layer is 2.43 ± 0.16 (0.18) Ma (±1σ), in agreement with previous paleomagnetic estimates of 2.58 Ma. Our results show that the age of the Xiashagou Fauna is consistent with the updated ages (2.21–1.95 Ma) of the Senèze and Olivola Faunas in Europe. The potential existence of an ecological corridor for faunal dispersals across northern Eurasia during this time period should be important to help contextualize the nature of the earliest hominin dispersals into and across Eurasia. As the first radio-isotopic ages for the Nihewan Basin sites, our results provide independent age control to anchor the magnetostratigraphy of the Early-Middle Pleistocene strata in the Nihewan Basin and to calibrate the Early Pleistocene stage of the Chinese Quaternary.

The overall and phased nitrogen leaching from a field bioretention during rainfall runoff events

Bioretention has been widely applied to mitigate urban runoff pollution. However, its net nitrogen leaching (outflow nitrogen concentration > inflow nitrogen concentration) frequently occurs and attracts more and more attention. In this paper, the variations of nitrogen leaching under different rainfall-runoff events (overall leaching) from a field bioretention were investigated based on a two-year continuous monitoring effort. The temporal course of leaching during each rainfall-runoff event (phased leaching) was analyzed by dividing the outflow into three phases in accordance with the volumes of residual water stored in the bioretention gravel and soil layers before the rain. The results indicate that: (1) The events with overall net leaching of ammonium (NH4+), nitrate (NO3−) and dissolved organic nitrogen (DON) account for 8%, 46% and 50% of the total monitored events, respectively. Overall net leaching occurs when the event mean concentration in inflow of current rain is lower than that of previous rain and the antecedent dry period (ADP) meets a certain threshold (e.g., ADP < 70 h for NO3− leaching and ADP > 24 h for DON leaching in this study); (2) The nitrogen leaching in the initial and final phase of outflow is respectively affected by the inflow of previous rain and current rain; while the nitrogen leaching in the middle phase is jointly affected by the inflow of previous rain and current rain; in addition, most NO3− leaches in the final phase, while most DON leaches in the initial phase; (3) Denitrification and assimilation in the bioretention during drying periods decreases NO3− leaching and increases DON leaching in the initial phase of outflow, respectively. This field study thus provides pertinent information that could help accurately assess and efficiently manage the risk of nitrogen leaching from a bioretention system.

Shear Strength Characteristics of Clay-Gravel Layer and Its Slope Failure Law and Mechanism

The Anqing Formation clay-gravel layer is widely distributed in the Anqing area of the upper reaches of the Wanjiang River. It is a typical soil-rock mixture composed of gravel and clay. The poor engineering properties of the clay-gravel layer are the main factors for the failure of the slope. On the basis of regional geological survey, the clay-gravel threshold, clay mineral composition and cementation characteristics of clay-gravel layer were studied. The in-situ horizontal push-shear tests under different gravel content, water environment and overlying load were designed and carried out, and its shear failure mode and strength were analyzed. The study found that the shear zone was in the shape of a broken line and was controlled by the particle size and distribution of the gravel. The shear strength of the clay-gravel layer is relatively high in the natural state due to the structure of the gravel and the friction and cementation force between the clay and the gravel. Water had the greatest influence on the shear strength of the clay-gravel layer, and the overlying load affected its shear strength within a certain range. The indoor rainfall erosion model test of the clay-gravel slope was carried out, and the failure and instability modes and mechanisms of the slope with different gravel contents were studied. When the gravel content was 30%, the failure of the slope surface was the development of gullies. The erosion damage process was similar to the soil slope. When the gravel content was 50%, affected by the distribution of gravel, the slope failure was manifested as the development of erosion pits, followed by local slumps, and finally the overall sliding in layers. When the gravel content was 70%, the clay particles on the slope were quickly washed away by the water flow, and the gravel skeleton of the slope formed a temporary relatively stable structure. After being disturbed, the gravel layer collapsed as a whole.

Using a Unique Retaining Method for Building Foundation Excavation: A Case Study on Sustainable Construction Methods and Circular Economy

The selection of a retaining method during the excavation of building foundations is always of paramount concern to engineers. In general, the application and use of steel H-shapes are typically practiced by designers to form the entire retaining system; however, sustainability issues, including carbon emission reduction, environment protection, material consumption, and resource circulation, are being increasingly considered when developing a new project. The Linkou Public Housing Project (LPHP), located in New Taipei City, Taiwan, is introduced in this paper to present a sustainable soil-retaining method that also exhibits the principles of a circular economy. The triangular shape of the foundation zone of the LPHP led to difficulty in setting the horizontal strut H-beam system. In this project, the “Anchor Pile with Steel Cable System (APSCS)” was adopted to retain the 11.5 m depth excavation for the LPHP foundation construction. The prime contents of the soil in the Linkou district comprises a laterite–gravel layer mixed with brown silty and sandy clay, with a groundwater level (G.L.) of −25 m. By adopting the sustainable APSCS method, the excavation of the LPHP foundation was safely completed. Approximately NT $350 million in direct and indirect costs of construction was saved, and the duration of the work was reduced by up to 90 days. Furthermore, the carbon emissions were reduced by 677.6 tons due to the diminished use of the steel H-shaped materials. The authors concluded that the use of the APSCS method in the LPHP was successful and it was a valuable reference for other similar projects. Moreover, the authors presented another retaining-system failure case, which was located near the LPHP site, to compare the success of the LPHP.

Experimental investigation on the dynamic tensile characteristics of conglomerate based on 3D SHPB system

The mechanical properties and failure characteristics of conglomerate, main components of gravel layer, are of great significance to the study of efficient drilling methods in gravel layer. However, there are few works published previously, especially rare in terms of dynamics. While drilling in gravel layer, the bottom hole rock is subjected to complex loads, including impact loading and in-situ stress. The static and dynamic tension behaviours of conglomerate are tested by outcrop in this paper. Based on GCTS and 3D SHPB systems respectively, the static and dynamic tensile properties are analyzed, and the energy consumption while failure and the influence of axial static load on dynamic tensile characteristics are discussed. Results show that the tensile characteristics of conglomerate have a significant strain rate correlation, and the dynamic tensile strength is significantly higher than that of static; The strength in both impact direction and axial direction increase linearly with the loading strain rate, while the failure strain decreases linearly; As there is no axial load and the strain rate is 140.31–248.95 s−1, the dynamic tensile strength is 75.86–109.91 MPa, and the strength growth factor is 10.55–15.29 between the dynamic and static tensile strength. Due to the energy absorbed by the specimen increases exponentially in the dynamic test, there are a great number of cracks produced accompanied by the collapse of large debris, manifested as the volume crushing failure mainly, while in the static test, there is mainly brittle splitting failure. The dynamic tensile strength can be reduced linearly by increasing the axial static load or reducing the dynamic load. The research has an important theoretical reference for the study of drilling technology and theory in the gravel-rich stratum.

An extended, 2.4-ka long record of western Pacific tsunamis and pumice rafts in northern Taiwan: Tsunami recurrence, pumice sources, and drifting routes

Encircled by arcs and trenches, the western Pacific region of the Philippine Sea is exposed to trans-oceanic tsunamis and pumice rafts. However, shortage of extended archive has limited our knowledge of tsunami recurrence, pumice sources, and drifting routes. This study identifies a backshore colluvium with three new pumice gravel layers in northern Taiwan, stratigraphically below four previously reported pumice-bearing paleotsunami deposits from the last millennium. The new layers are attributed to tsunamis, based on foreshore-derived sediments, facies characteristics reflecting suspension-rich turbulent flow process, supratidal locations exceeding typhoon surge heights, and mismatched super typhoon occurrences. The tsunami record therefore extends in duration from 1.0 to 2.4 ka with an increase in event number from four to seven, which unfolds new time intervals, stretches the recurrence from 100–400 to 100–800 years, and indicates complicated tsunami occurrences and sources in this region. Simultaneously, a stranded pumice archive is established by six of the seven paleotsunami deposits with abundant pumices rounded by grain-to-grain abrasion during drifting. The pumices consist of black, shoshonitic trachyte–trachyandesite grains and white, low-K dacite–rhyolite grains, indicating diverse sources and drifting routes. The unique alkali and adjoining subalkaline volcano provinces of the Izu-Bonin-Mariana Arc might have successively generated pumice rafts since 2.4 ka that embarked the Kuroshio counter and branch currents for northern Taiwan in a ∼2000-km-long course across the Philippine Sea. White rhyolite pumice domination is also present and comparable in composition to the southern Ryukyu pumice, indicating a ∼200 km-long northwest-bound route.

Otsenka nadezhnosti kirpichnogo zdaniya na svainom fundamente v usloviyakh razvitiya neravnomernykh osadok [Reliability of brick building on pile foundation in relative settlement conditions

The paper studies an extended five-storey brick building on a pile foundation, subjected to significant deformation. The building reliability is assessed after the instrumented survey. During the building construction and operation, its spatial stiffness is broken with the crack formation in the walls and foundation frame due to an insufficient pile immersion in the gravel layer in difficult engineering and geological conditions. Due to accident technical conditions of the brick walls, the superstructure block is examined in the first phase. The second step includes the examination of the foundation frame and pile using bored pits. The MicroFe software is used for finite element modeling of the stress-strain state of the pile foundation and footing strength of the footing–foundation–building system. The obtained results allow assessing the building reliability and developing recommendations on the pile foundation serviceability.

The exploration of gravel layer with 3D magnetotelluric data

The Horgos area of the thrust belt on the southern margin of the Junggar Basin has a good prospect for oil and gas exploration. However, because of the complex surface conditions and the coverage of the gravel layer, the seismic data on the southern margin thrust belt have some poor imaging, which makes the three-row structural pattern unclear. It is urgent to use 3D magnetotelluric (MT) exploration to investigate the distribution of gravel layer for seismic processing to build shallow model. In this paper, a 3D geoelectric model is established using MT data and logging data collected in the study area. Through the forward modeling and inversion calculation, the feasibility of using 3D MT data to explore the high resistivity gravel layer of various thickness is verified. Phase tensor analyses indicate the shallow (> 0.1 Hz) electrical structure is mainly 1D or 2D, while the deep structure is affected by 3D structure. The 3D conjugate gradients inversion method is used to process the MT data of the study area, the forward responses of the inversion result fit the observed data well and the electrical layers of the 3D inversion is consistent with the electrical characteristic revealed by the electric logging data. All these indicate the reliability of the 3D inversion results. The 3D MT results are first used to interpret the distribution and thickness of two sets of gravel layers in the study area. It is mainly used to assist the seismic exploration to solve problems involving exploration of complex surface carbonate rocks, exploration of deep complex structures and identification of shallow lithology. It proves that 3D MT is an effective technique for the gravel and shallow lithology exploration in similar regions.

Development of Creep Deformations during Service Life: A Comparison of CLT and TCC Floor Constructions

Cross-laminated timber (CLT) slabs in residential buildings need additional weight, e.g., in the form of screeds or gravel layers, to fulfill the criterion for the highest impact-sound class. The additional mass is, however, not exploited for the load bearing behavior, but adds additional weight and leads to an increased height of the floor construction. In this study, such a CLT floor construction with a construction height of 380 mm is compared with a composite slab consisting of a CLT plate with a concrete layer on top with a floor construction height of 330 mm. The timber concrete composite (TCC) slab has a different creep behavior than the CLT slab. Thus, the development of the time-dependent deflections over the service life are of interest. A straightforward hybrid approach is developed, which exploits advanced multiscale-based material models for the individual composite layers and a standardized structural analysis method for the structural slab to model its linear creep behavior. The introduced approach allows to investigate load redistribution between the layers of the composite structure and the evolution of the deflection of the slab during the service life. The investigated slab types show a similar deflection after 50 years, while the development of the deflections over time are different. The CLT slab has a smaller overall stiffness at the beginning but a smaller decrease in stiffness over time than the investigated TCC slab.

Geoelectrical Assessment of Groundwater Potential within Zamfara and its Environs, Northwestern Nigeria

Groundwater potential assessment was carried out within Zamfara environs, Northwestern Nigeria using geoelectrical technique with a view of solving the problem of incessant failure of boreholes in the study area. A total of one hundred and eighty-three (183) vertical electrical soundings (VES) were used to identify potential groundwater bearing zones capable of sustaining economic development of the study area. Two hydrogeological units were investigated (basement rock units and sedimentary rock unit), using Omega resistivity meter Model No. 122, to measure and record the resistance of the subsurface by Schlumberger configuration. The data obtained were interpreted quantitatively and qualitatively using the partial curve matching and computer iteration techniques to generate the first order geoelectric parameters. Generally, the VES result from the basement rock units revealed, four geoelectric layers which correspond to lateritic top soil, weathered basement (clay), partially fractured layer/fractured layer and fresh basement. The weathered/fractured layer was identified as the water bearing layer, within the basement rock units of the study area. From geospatial analysis of both weathered thickness/fracture thickness layers, South and Northeastern part tends to be the most prospective area with the best hydrogeologic conditions for borehole siting within the basement rock units. Consequently, three geo-electric layers were delineated from VES result obtained from Gundumi formation, which correspond to sandy clayey top/gravelly sandy top soil, second layer are mostly silty-clay/compacted sandstone/sandy gravel layers, the third layer were majorly saturated sandstone in some instances silty clay. However, the aquiferous layer is saturated sandstone/sandy gravel layer. The Dar Zarrouk result revealed excellent groundwater potential within the Gundumi formation. The values of coefficient anisotropy obtained from Gundumi rock units range from 0.44 to 3.79, which implies moderate saturation of groundwater. This is an indication that the aquifers of the Gundumi formation is more promising and it can be tap for both domestic and agricultural uses.&#x0D; Keywords: Vertical electrical sounding; Fractured layer; Saturated Sandstone; Basement rock units; Gundumi formation

Analytical model of flow velocity in gravel-bed streams under the effect of gravel array with different densities

The standard exponential and logarithmic laws for flow velocity evaluation cannot be applied for gravel-bed streams due to the effect of large-scale roughness. An analytical model based on a two-layer subdivision approach was developed to predict flow velocity over a gravel array with different densities. The velocity distribution in the gravel layer was derived by solving the Darcy-Forchheimer-Brinkman (DFB) differential equation based on the concept of porous medium flows. The velocity in the surface layer was modeled by the mixing length theory with the length scale modified by taking into account the porous effect of the gravel (ball) arrays. To assess the model, flow velocities over gravel beds simulated by Ping-Pong ball arrays with different densities (or porosities) were measured in a laboratory flume. The results show that the predicted velocities by this subdivision model agree well with experimental data, reflecting that the porosity of the gravel array essentially impacts the flows both in the gravel layer and surface layer. In comparison with the existing models not considering the porous effect of the gravel bed, this model can effectively predict vertical velocity distributions and thereby flow resistances in gravel streams. The permeable interface velocity atop the gravel layer, as the boundary condition for the two-layer model, is sensitive to the bed context effect rather than the hydraulic effect, suggesting that the inflection point of the full velocity profile might be vital in determining the accuracy of the model. Moreover, with other data sources over dense gravel-bed, our model is suitable for data pre-dealt with the spatially averaging, where the spatial non-uniformity effect is great.

Coherence between sunlight quantum and soil water content in the shallow Quaternary gravel layer: Evidence of the spectral analysis

Due to the heterogeneity and nonlinear process in the unsaturated soil zone, it is challenging to represent the analytical mechanism and actual in-situ water content in the soil layer. With this in mind, this study provides a novel approach to discern the water content in the shallow Quaternary gravel layer at various depths using temporal sunlight and air temperature observation. It demonstrates significant components in spectral density to evaluate the crucial importance concerning the time-dependent soil water content, sunlight quantum, and air temperature. It shows that the soil water content at 10 cm depth can distinguish the fluctuated manner of light quantum at the time lag of about 6.6 and 5.1 h for diurnal and semidiurnal processes, respectively. The time progress of soil water contents at 30 cm depth is less relevant to 10 cm depth, but the phase at 60 and 120 cm depth is nearly in phase. Due to heterogeneity in the shallow layer, the temporal changes of soil water content below 10 cm depth have varying coherence degrees. Thus, using spectral analysis, practically estimating the coherence and time lag between light quantum, air temperature, and soil water content becomes feasible and achievable.

A Solution to Transportation Problem due to Surface Runoff or Storm Water in Panna City Madhya Pradesh

As urbanization is increasing day by day the runoff or storm water in a small city Panna is increasing due to which the transportation problem occurs in the city which leads to an improper flow of transportation in the city. Due to urbanization the proper groundwater recharge technique is not present which leads to increase of runoff in the city, as the soil surface is permeable in which groundwater recharge by infiltration can occur is reducing and resulting in increased surface run off in the Panna city. The effect of transportation flow can be reduced by use of runoff water for increase of water table of city. Infiltration system like infiltration trenches should be made for reducing surface runoff which also increases the infiltration rate of the city, by making of infiltration trenches an area below the footpath and providing filter media in it which has a different layer of gravel and sand due to which filtered water goes inside the earth surface. This helps in reducing the storm water or surface runoff in small city Panna.

Analysis of Behaviors of the Railway Subgrade with a New Waterproof Seal Layer.

This study proposes a new waterproof sealing layer to reduce the impact of water on subgrade beds. The proposed waterproof sealing layer is composed of a polyurethane adhesive (PA) mixture, which aims to control interlaminar deformation and prevent seepage. A variety of laboratory tests were first performed to analyze the attenuation characteristics and mechanical properties of various polyurethane polymer (PP)-improved gravel mixtures under thermohydraulic coupling effects. In addition, a waterproof performance model test of the PP-improved gravel layer was conducted to investigate its waterproof and drainage performance and hydraulic damage mechanism. Finally, the feasibility and effectiveness of the surface structure of the waterproof drainage subgrade bed containing the PA mixture was tested in combination with the treatment project of the Ciyaowan station of the Baoshen heavy-haul railway. According to the experimental and model results, (1) the waterproof layer containing the polyurethane mixture exhibited satisfactory stiffness, elasticity and flexibility. The waterproof layer containing the polyurethane mixture also controlled the deformation between layers, and its mechanical properties remained stable. (2) The waterproof layer with the dense polyurethane mixture performed well in terms of the waterproof aspect, and no infiltration occurred under cyclic load (3). Long-term field monitoring revealed that the effect of the implementation of a PP-improved gravel layer to treat mud pumping was remarkable. The settlement of the PP-improved gravel layer only reached 13.21 mm, and the settlement remained stable in the later stage.