Foot Of Slope Research Articles

黄土高原地区森林生态系统地下生物量影响因素

根系将土壤和大气相连与植物体共同影响生态系统的碳循环，同时根系也是森林生态系统土壤碳库的重要来源。研究表明森林地下生物量受生物因素和非生物因素影响，因此研究各因素对根系生物量的影响对精确估算土壤碳库至关重要。基于我国相关部门的观测及调查数据，通过标准化计算和统计分析来量化各因素对黄土高原地区地下生物量的影响。结果表明：黄土高原森林生态系统地下生物量主要分布在11.99-27.46 Mg/hm²之间；非生物因素对地下生物量起主导作用，其中降雨量和地形影响最为显著；不同土壤类型地下生物量表现出：棕壤 > 褐土 > 岩性土；不同森林类型地下生物量大小为：针叶林 > 针阔叶混交林 > 落叶阔叶林；不同地形地下生物量由大到小为：丘陵、山地 > 高原、平原；地下生物量在坡位上的分布大小为：坡麓 > 上、中、下三个坡位 > 平地；人类活动和动物活动干扰对地下生物量的影响没有显著差异。另外，在分析中发现若影响因素中含经纬度，非生物和生物因素对地下生物量的影响程度分别为68.9%和31.1%；若影响因素中不含经纬度，非生物和生物因素对地下生物量的影响程度分别为81.1%和18.9%，说明经纬度与其他因素存在很强的相关性，并严重影响着生物因素和非生物因素对森林生态系统地下生物量的比重。研究结果对地下生物量的估测有一定的意义，可以为森林植被如何通过根系适应环境的研究提供参考，为植被恢复、森林经营管理及地下部分碳循环的研究提供依据。;Root which connects soil and atmosphere and plant have a combined effect on the carbon cycle in the ecosystem. Meanwhile, root is also an important source of soil carbon pool in forest ecosystem. Previous studies showed that the forest underground biomass was affected by biological factors and abiotic factors, thus it is of great importance to determine the effect of various factors on root biomass for accurate estimation of soil carbon pool. Based on the observation and survey data of relevant departments in China, standardized calculation and statistical analysis methods were used to quantify the effect of various factors on the underground biomass in the Loess Plateau. There are 15 factors in this study, among which the abiotic factors are longitude, latitude, annual rainfall, annual mean temperature, altitude, topography, slope direction, slope position, slope angle and soil type. The other five factors are biotic factors, which are forest type, forest origin, forest age, animal activities and human activities. The results showed that the underground biomass in forest ecosystem in the Loess Plateau ranged from 11.99 Mg/hm² to 27.46 Mg/hm². Abiotic factors had dominant influence in the underground biomass, particularly for the rainfall and topography. The order for underground biomass was brown > cinnamon > lithologic soil in different soil types, coniferous > coniferous broad-leaved mixed > deciduous broad-leaved forest in different forest types, hillly and mountainous > plateau and plain terrain in different topography respectively. The distribution of underground biomass on the slope was:the foot of mountain slopes > upper, middle and lower slope > flat land. There was no significant difference between human activities and animal activities. We found that the proportion of biotic and abiotic factors on the underground biomass was severely affected by longitude and latitude. It was 68.9% and 31.1% with longitude and latitude factors, otherwise it was 81.1% and 18.9%, respectively. The results indicated that latitude and longitude had a strong correlation with other factors. In addition, controlling a single factor explained the influence of the other factors on the underground biomass. For example, the main factors determining the underground biomass in humid area were annual temperature (19%) and slope position (19%). Our study could have implications for the estimation of underground biomass, which could provide a reference for plantation root adaptation to the environment, and put forward the theoretical basis for the study of vegetation restoration, forest management and underground carbon cycle.

Терригенное лавинное осадконакопление на примере пермских толщ Охотского и Аян-Юряхского бассейнов (Северо-Восток Азии)

Terrigenous avalanche sedimentation in Northeast Asia is considered on the example of the Permian strata of the Okhotsk and Ayan-Yuryakh basins. These deposits form a complicated sedimentary complex undergoing regular changes in the direction from the southwest (from the Okhotsk massif) to the northeast (to the Ayan-Yuryakh anticlinorium) - from continental and coastal-marine environments to deep-water, corresponding to the conditions of the foot of the continental slope. An important specific feature of this basins is the widespread development of deep-water deposits, primarily of various types of gravitites, among which facies of proximal and distal turbidites, grain and clay flows, and diamictites (debrites) can be distinguished. The facies of nepheloidites and disturbed-bedded deep-water siltstones also play a significant role. Shallower sediments are less widespread and were formed within the shelf of the Okhotsk massif. They are represented by facies of coastal sandstones, sandstones and siltstones of the inner part of the shelf and siltstones of the outer part of the shelf. Almost all types of rocks contain one or another fraction of pyroclastic material, the amount of which increases with approaching the Okhotsk massif, where some probable centers of eruptions of the Okhotsk-Taigonos volcanic arc were located. In the evolution of the basins under consideration, the general stages in the development of the entire system of northeast Asian basins are clearly established, which was obviously determined by reasons of a global scale. The first three stages correspond to the regional superhorizons (Munugudzhakian, Dzhigdalian, and Omolonian), the last three, to the Gizhigian Horizon and subhorizons of the Khivachian Horizon).

Rapid identification of landslide, collapse and crack based on low-altitude remote sensing image of UAV

Landslides, collapses and cracks are the main types of geological hazards, which threaten the safety of human life and property at all times. In emergency surveying and mapping, it is time-consuming and laborious to use the method of field artificial investigation and recognition and using satellite image to identify ground hazards, there are some problems, such as time lag, low resolution, and difficult to select the map on demand. In this paper, a 10 cm per pixel resolution photogrammetry of a geological hazard -prone area of Taohuagou, Shanxi Province, China is carried out by DJ 4 UAV. The digital orthophoto model (DOM), digital surface model (DSM) and three-dimensional point cloud model (3 DPCM) are generated in this region. The method of visual interpretation of cracks based on DOM (as main) -3DPCM (as auxiliary) and landslide and collapse based on 3DPCM (as main) — DOM and DSM (as auxiliary) are proposed. Based on the low altitude remote sensing image of UAV, the shape characteristics, geological characteristics and distribution of the identified hazards are analyzed. The results show that using UAV low altitude remote sensing image, the method of combination of main and auxiliary data can quickly and accurately identify landslide, collapse and crack, the accuracy of crack identification is 93%, and the accuracy of landslide and collapse identification is 100%. It mainly occurs in silty clay and mudstone geology and is greatly affected by slope foot excavation. This study can play a great role in the recognition of sudden hazards by low altitude remote sensing images of UAV.

Indoor model test of red clay slope under evaporation-rainfall

Evaporation-rainfall is one of the main causes of red clay slope failure. In order to explore the evolution law and mechanism of red clay slope failure under evaporation-rainfall, this paper takes Guizhou red clay as the research object, establishes slope model in laboratory, and analyzes the failure characteristics, failure mode and failure mechanism of red clay slope under evaporation-rainfall. The test results show that the failure mode of red clay slope under evaporation-rainfall is: splash erosion and surface erosion stage → crack development stage → gully formation stage → gully development stage → local collapse stage → slope foot collapse stage. During the test, there is no obvious sliding surface on the slope. In the process of rainfall, the free water inside the slope converges to the foot of the slope under the action of gravity, which results in the maximum moisture content at the foot of the slope, and the strength of the soil decreases sharply. The local collapse occurs at the foot of the slope first. When several collapses are connected and the structure of the slope foot cannot support the weight of the upper shallow soil, the collapse occurs to the middle and upper part of the slope exhibition.

Slope failure mechanism affected by mining subsidence: a case study of highway slopes in Yangquan, Shanxi Province, China

This paper presents details of highway slopes affected by a mining subsidence event that occurred in the Yangquan coal mining area of China in 2016. To ascertain the developmental characteristics of surface deformation, a few methods were applied for investigation and monitoring, such as multiple field investigations, unmanned aerial vehicle measurements, and time-series interferometric synthetic-aperture radar techniques. An accurate numerical simulation was conducted on two slopes for stability analysis and mining subsidence prediction. Results show that the mining subsidence developed from south to north, which was consistent with the mining direction; two subsidence centers were distributed on the ground, and the north one was located in the southeast slope foot of the highway. The influence of the mining subsidence whose subsidence magnitude reached 4 m is obviously different on both sides of the highway. Although the rock and soil structure were damaged seriously, the northwest slope was completely unstable, whereas the southeast slope remained standing. The differences were studied to illuminate that slope instability is not only due to the mechanical properties of rock mass decrease dramatically but also relates to the direction of horizontal traction force, the spatial distribution of the working face, and the effective free surface of the slope. This paper presents a case of mining landslide failure for researchers.

Influence of the Reservoir Position on Sponge Slope Stability

Sponge slopes have received increasing attention due to their unique ecological advantage. Based on the three-dimensional numerical calculation model, the paper explores the influence of the position of the reservoir on the safety and stability of the slope and compares the variation characteristics of the sliding displacement and stress field of the slope. The results show that when the reservoir is built below the slope foot or at the slope top, the disturbance is relatively small, and the maximum displacement of the slope is smaller. Shear stress concentration occurs near the wall of the reservoir, and it increases and then decreases as the height of the reservoir increases. Besides, the maximum principal stress appears near the reservoir wall and the maximum principal stress decreases as the position of the reservoir increases.

Significance to hydrocarbon exploration of terrestrial organic matter introduced into deep marine systems: Insights from the Lower Cretaceous in the Levant Basin

Oil shows from wells in the Levant Basin and Egypt are suggestive of potential economic discoveries within unpenetrated Mesozoic reservoirs in the Eastern Mediterranean. Analysis of some of these oils indicate a non-marine source of mixed deltaic-terrestrial or lacustrine origin for the organic matter. Data from Barremian-Aptian sediments from the MNUPH-1 core in northern Israel opens a window on potential importance of terrestrial-sourced kerogen deposited in source rocks in a marine depositional environment.Core analyses of the Barremian Nabi Sa'id Fm. demonstrate the occurrence of a gas-prone immature source rock of >77 m gross thickness averaging 4.6% TOC, peaking at 37% TOC. Rock-Eval pyrolysis, biomarker n-alkane, sterane, and tricyclic terpane indices, atomic C/N ratios, and δ13Corg ranges indicate mixed terrestrial-marine organic source rocks for the Barremian, while higher up, the Aptian Hidra Fm. contains source rocks with organic matter derived dominantly from carbohydrate-rich land plants. The interval at MNUPH-1 includes abundant evidence for off-shelf mass transport of terrestrial and proximal marine sediments into the deep marine basin. These features are used to explain the anomaly of a terrestrial source for organic matter in this setting. Mass transport and consequent mixing of distal marine, proximal marine and land-derived sediment is, in fact, the norm at the foot of continental slopes globally.The dominantly type III source rocks described here would be unlikely to expel oil but might produce thermogenic gas. Thermogenic gas identified in similar marine settings might wrongly be interpreted as having been generated from marine organic matter, misleadingly indicative of a prospective oil source. When prospecting for deep-rooted hydrocarbon accumulations in offshore marine settings, an alternative system dominated by basinward sediment transport of gas-prone ‘terrestrial’ source rocks into strategically-positioned toe-of-slope marine settings, is supported here, and could well be producing gas in the Levant Basin.

Liquefaction performance and deformation of slightly sloping site in floodplains of the lower reaches of Yangtze River

Serious seismic damage is expected owing to the occurrence of lateral displacement following soil liquefaction after a strong earthquake. Currently, there is a need for increased research on the lateral deformation occurring inside a liquefied foundation and its spatial distribution characteristics. Considering the initial geostatic stress of a slightly sloping site, a finite-element model that reflects the liquefaction-induced slippage of the liquefiable site with a slightly inclined ground was designed. According to the results, the steeper the ground slope is, the weaker the soil liquefaction in the slope body will be. As the ground inclination and the intensity of input ground motion vary, the lateral slippage of the liquefiable soil layer transforms from the liquefaction-induced slipping along a single sliding surface to that along multiple sliding surfaces. The dominant lateral displacement of liquefiable soil layers in the slope body changes as well, from liquefaction-induced slippage of soil to largely large single-direction accumulated shear deformation of softening soil, as a result of the drastically reduced intensity of the liquefiable soil. In addition, a similar linear relationship is found among the maximum lateral displacement, the ground settlement near the slope crest, and the ground uplift near the slope foot.

Interpretation, age and significance of a relict paraglacial and periglacial boulder-dominated landform assemblage in Alnesdalen, Romsdalsalpane, southern Norway

A boulder-dominated landform assemblage in an alpine setting in Norway is described, interpreted and dated using a combination of Schmidt-hammer exposure-age dating (SHD) and cosmogenic 10Be surface-exposure dating. The origin and formation of these features is determined from their morphology, topographic setting and age. Three main components of the assemblage are recognized. First a ~300 m long and ~160 m wide, tongue-shaped rock-slope failure with a SHD age of 11.49 ± 0.82–12.96 ± 0.86 ka is identified on the basis of its planform, thickness, ‘runout distance’ and association with a fractured backing scarp. This is interpreted as a relict paraglacial landform triggered by deglaciation. Second, a 400-m long unequivocal pronival (protalus) rampart with an SHD age of 6.95 ± 0.97–8.35 ± 1.21 ka is identified on the basis of its narrow ridge form aligned close to the foot of an extensive talus slope. Although formation of the rampart probably commenced with deglaciation, the younger SHD ages indicate formation at a diminishing rate through the Holocene. Third, a ~550 m by ~150 m lobate component with transverse ridges, longitudinal and transverse depressions and enclosed pits, previously identified as a rock glacier, is dated to 11.33 ± 0.83–13.33 ± 0.90 ka with the Schmidt hammer and between 13.3 ± 2.0–14.7 ± 2.0 ka with 10Be. This third component may also be a product of rock-slope failure but attribution to rock-glacier creep associated with either interstitial ice (permafrost) or buried glacier ice during the Allerød Interstadial – Younger Dryas Stadial, and to which one or more rock-slope failures contributed debris, cannot be rejected. The advantages and limitations of compiling such evidence for identifying, differentiating and classifying apparently similar boulder-dominated colluvial landforms are exemplified.

Formation Mechanism and Control Measures of Sliding Surface about Bedding Slope Containing Weak Interlayer

During the mining process of Hami open-pit coal mine, a large number of cracks appeared on the ground surface near the top of the end slope, which affected the stability of the slope and the subsequent safe mining of resources. By analyzing the deformation of rock stratum, the position of weak interlayer in the slope was determined. Considering the rock mass with weak interlayer as a complete mechanical system, the mechanical model of the rock mass system with weak interlayer was established, and the evaluation index of rock failure degree before slope instability was proposed. The failure mode of slope with weak interlayer is as follows: sliding failure-cutting layer failure-tension failure. The safety factor of slope decreases first and then increases with the increase of the depth of the weak interlayer, and gradually decreases with the increase of the inclination of the weak interlayer. The pressing foot of slope can be used in landslide control of slope with weak interlayers, and the optimal pressing foot solution to ensure the safe mining of final slope coal resources was determined to be a pressing foot height of 35 m and pressing foot width of 20 m.

Evolution of the hydrogeological structure and disaster-generating mechanisms of landslides in loess slopes of the southern Jingyang Plateau, Shaanxi, China

Landslides in loess slopes are mainly triggered by heterogeneity in hydrogeology. The southern Jingyang Plateau (China) was selected to characterize the geological structure and groundwater synergetic mechanisms that trigger landslides through groundwater–soil interactions. The study investigated hydrogeological and irrigation factors, the groundwater-perching effect of paleosols, the groundwater-conducting effect of fissures, and the damming effect of slide mass accumulation. A two-dimensional steady unsaturated numerical seepage model of a vertical section was established to simulate landslide evolution induced by irrigation and fissures. Long-term irrigation causes springs and weak zones to develop when the water table rises above the slope foot. Perched groundwater can lead superfluous water to migrate to the slope edge. The downward expansion of fissures and water migration can mutually cause extension of weak zones beneath fissures. A slip zone may appear when the weak zone connects to weaknesses at the slope foot, which forms a larger foot along the slope. Landslides occur frequently under the combined action of hydrostatic pressure from water-filled cracks, dynamic water pressure from a rising water table, and depressed sliding resistance caused by water enrichment in soil. After sliding, the slide mass will accumulate at the slope foot, blocking the original groundwater drainage point, so the water level may rise again, leading to subsequent landslides developing with new fissures and continued irrigation. Investigations in areas irrigated by groundwater wells showed that pumping can lower the water table in the soil and eliminate weak zones at the slope foot, effectively reducing the occurrence of landslides.

WIND-TUNNEL EXPERIMENT ON SAND DEPOSITION MECHANISM AND OPTIMAL MEASURES OF WIND-BREAK WALL ALONG RAILWAY IN STRONG WIND AREA

The Lan-Xin Railway II from Lanzhou to Xinjiang is the first high-speed railway which passes through the strong wind zones in the world, and it passes through the famous Yan Dun, Hundred Miles, Thirty Miles and Dabancheng wind zones. The total length of the railway is more than 462.4 kilometers, accounting for 65.1${\%}$ of the total length of railway in Xinjiang. Strong winds can do great harm to the operation, maintenance and transportation of railways. In order to resist the damage of strong wind to train, a large number of wind-break walls were built along the Lan-Xin Railway II. The wind-break wall reduces the strong wind damage, but brings a new disaster caused by sand sedimentation. To solve the problem of this engineering practice, this paper puts forward the idea of setting up the second retaining wall at different positions on the leeward side of existing wind-break wall to reduce sand particles sedimentation. The wind tunnel experiment was employed to simulate the wind-sand flow environment. Three typical configurations are considered: 1) single wind-break wall; 2) two walls and the second one locates at the top of the leeward slope of subgrade; 3) two walls and the second one locates at the foot of the leeward slope of subgrade. The decrease rates of the horizontal velocity, number density, horizontal transport flux and deposition rate of sand particles at the height of 0.1 m after the second wall are respectively 8${\%}$$\sim $12${\%}$, 51${\%}$$\sim $69${\%}$, 20${\%}$$\sim $73${\%}$ and 26${\%}$$\sim $38${\%}$, by comparing to the case without the second wall. It is found that the second retaining wall at the foot of the leeward slope of subgrade is optimal. The research result of this paper is helpful to optimize the preventing sand sedimentation measures of existing railway lines and towns in the strong wind zone.

Physical model test of seepage and deformation characteristics of shallow expansive soil slope

Large-scale physical model test on expansive soil slope at a shallow depth is conducted with the aim of monitoring moisture content and swelling deformation. In this paper, a wedge-shaped model box with a bevel at the bottom was developed to reflect the actual channel slope in the South-to-North Water Transfer Project. The results provide an improved understanding of the physical behavior and failure mode of a saturated-unsaturated expansive soil slope subjected to moisture content variation. Showing that, after rainfall, the surface soil quickly became saturated, with the deeper soil moisture remaining unchanged. Infiltration depth, speed, and saturation region reduced with the increasing height along the slope. Surface displacement increased from slope foot to slope shoulder, and significantly attenuated towards the depth. Horizontal displacement was about 1/3–1/2 of the vertical displacement. The larger the increment of the soil moisture, the greater the surface deformation. Soil showed dehydration shrinkage with fissures first appearing in the soil surface and expands downward with continuing evaporation. The junction of saturated-unsaturated zone and the wet-dry interface were the areas of stress concentration. Swelling effect led to stress field redistribution in the expansive soil slope, and it was the most important factor causing expansive soil shallow slope failure.

Contourites and Gravitites on the Rio Grande Rise, Southwest Atlantic Ocean (Seismoacoustic Data)

Morphology of the Rio Grande Rise and the acoustic structure of different types of deposits in its uppermost sedimentary cover were discussed based on high-resolution seismoacoustic profiling of cruises #32 (2010) and #52 (2016) of R/V Akademik Ioffe. Slopes of the Rio Grande Rise are composed mainly of landslide deposits and gravitites, but contourite sedimentation is possible on its southern slope. Contourite sedimentary waves and, probably, small drifts are identified in the Cruzeiro do Sul Trough at the top of the Rio Grande Rise. Mixed gravitite–contourite sedimentary systems seem to be located at the foot of northern and southern slopes. The downslope density flows and the Antarctic Bottom Water (AABW) contourite current are responsible for the formation of these features.

Geological and biological diversity of seeps in the Sea of Marmara

The Sea of Marmara hosts part of the North Anatolian Fault as an active submarine strike-slip fault. This area has suffered numerous earthquakes and presents a major seismic risk. Although the Sea of Marmara has been studied for many years, the link between geological morphostructures, the nature of fluids and biological communities is still rarely described. During the Marsite cruise (November 2014), dives with Remotely Operated Vehicle (ROV) VICTOR 6000 focused on detailed seafloor explorations of four different areas: the Central and Western highs and the Tekirdağ and Çinarcik basins. Based on 130 h of in situ videos, high-resolution seafloor mapping of seeps was conducted, emphasizing their significant geological and biological diversity from one seeping site to another, from one basin/high to another. Gas bubbles (CH4, CO2), shimmering water (brine, marine and fresh water) and oil, escape from the seafloor into the water column with low to strong fluxes. Black patches of reduced sediments, authigenic carbonate crusts and chimneys compose the seep environments with various types of bacterial mats and chemosynthetic fauna. Several venting sites discovered during previous cruises are still active 7–12 years later. The seeps are mostly, but not only, focalized along the Main Marmara Fault (MMF), at the southern border of the Tekirdağ Basin and along the Western High. Fluid emission is also occurring at secondary faults and at their intersection with the MMF. Our study emphasizes the location of seeps at the foot of slopes, gully outlets and crossroads. Sedimentary features, such as mass wastings, stratigraphic discontinuities or canyons, also interact with fluid emissions. The observed fauna is dominated by Bathymodiolinae, Vesicomyidae, Lucinidae-like empty shells and tubiculous worms resembling Ampharetidae polychatea. Most of the symbiont-bearing taxa encountered and previously sampled in the Marmara Sea, are characterized by thiotrophic symbioses. Vesicomyids and Idas sp. mussels are present at gas seeps, but also in areas where crude oil escapes from the seafloor. Moreover, other taxa unusually encountered at cold seeps such as large-sized amphipod and vagile worms were observed in the Çinarcik Basin. Idas-like mussels were observed in the western part of the Sea of Marmara, in the Tekirdağ Basin and possibly on the Western High active seep sites. There, the sampled fluids had high methane content (reaching 65 μmol/l) but not as high as on the Central High (363 μmol/l) and Çinarcik Basin (228 μmol/l) where no mussels were observed in the video records. Bottom waters oxygen levels in the Sea of Marmara showed a west to east decreasing gradient (57–8.5 μmol/l). These oxygen conditions, which fall under the limit of Oxygen Minimum Zones (OMZ <20 μm/l) in the eastern part, may impact benthic fauna and explain the absence of symbiotrophic bivalves at cold seep sites of the Çinarcik Basin, whereas densely aggregated amphipods, likely more tolerant to oxygen stress were observed in the seepage area. Finally, no specific fauna was observed near the CO2-rich seep sites. First observations suggest that seep fauna composition in the Sea of Marmara does not seem to be strongly influenced by the nature (e.g., oil, gas bubbling, brines) of fluid venting through seeps. The seep environments are highly variable and characterized by distinctive geological morphostructures. They sustain typical Mediterranean cold seep fauna, but also unusual communities likely related to the interaction of seeps with hypoxic conditions.

Recognition of the coastal dune migration micro-deformation in Changli Gold Coast of China based on GB-InSAR

Based on an analysis of current research regarding dune migration and deformation monitoring methods, high-precision ground-based synthetic aperture radar (GB-InSAR) interferometry was used for continuous dynamic monitoring of the migration and deformation of dunes in Changli Gold Coast in Hebei Province, China, a typical area of coastal dunes. Methods for interpretation and key data processing were investigated. The results showed that the maximum deformation of dunes reached 7 mm during the monitoring period and that the deformation of the topset of the dune was greater than that of the slope foot. With GB-InSAR technology, millimeter-scale deformation can be effectively recognized. This method can be applied to monitor real-time dynamic micro-deformation of coastal dunes because of its excellent precision. It offers good application prospects if popularized and applied in coastal dune migration monitoring. This study not only enriches the research methods and content for studying coastal wind–sand issues but also provides a scientific basis for the protection and development of the study area.

Spatial variation of soil physical properties and its relationship with plant biomass in degraded slopes in dry-hot valley region of Southwest China

Soil properties are one of the most important factors affecting the distribution and growth of plants in arid and semi-arid regions, especially in the dry-hot valley of southwest China, where desertification is a serious environmental problem deteriorating the dryland ecosystems. However, the spatial variation of soil physical properties and its relationship with plant productivity in degraded slopes is not yet fully understood. In this study, three parallel downslope transects were built on a typical degraded slope in the dry-hot valley of Jinsha River, and soil physical properties (including soil particle size, bulk density (BD), total porosity (TP), capillary porosity (CP), noncapillary porosity (NP), saturated water capacity (SWC), capillary water capacity (CWC), field water capacity (FWC), and hydraulic conductivity (Ks)) at two soil depths (0–10 cm and 10–20 cm) and plant biomass (reflected by aboveground biomass) were measured. The results indicated that the sand content, TP, NP, SWC, CWC, and Ks increased firstly and then decreased, while the silt content and BD decreased firstly and then increased from upper slope to lower slope. Plant biomass was only observed in middle and lower slopes, and that in the lower slope was decreased significantly to slope foot. Slope position and soil depth had significant effects (P < 0.05) on soil physical properties, indicating that topography and soil depth play a key role in driving the spatial variation in soil physical properties. Simple linear regression analysis showed that Ks, sand, and silt content are the key soil indicators affecting plant growth, and the soil layer differences in BD, CWC, and FWC are also the important factors affecting plant productivity. Our findings highlight the spatial variation of soil physical properties, and plant biomass is attributed to the interactions of topography-soil-plant, which is critical for the healthy function of degraded slopes. Such findings provide an important basis for ecological restoration and management in degraded regions.

Refining the Uluzzian through a new lithic assemblage from Roccia San Sebastiano (Mondragone, southern Italy)

Roccia San Sebastiano is a tectonic-karstic cave located at the foot of the southern slope of Mt. Massico, in the territory of Mondragone (Caserta) in Campania (southern Italy). Systematic excavation has been carried out since 2001, leading to the partial exploration of an important Pleistocene deposit, extraordinarily rich in lithic and faunal remains. The aim of this paper is to (1) present the stratigraphic sequence of Roccia San Sebastiano, and (2) technologically describe the lithic materials of squares F14 t18, t19, t20; E16 t16, t17, t18 recently recognised as Uluzzian. The stratigraphic sequence is more than 3 m thick and dates from the Middle to the Upper Palaeolithic. It contains different techno-complexes: Gravettian, Aurignacian, Uluzzian and Mousterian. In the Uluzzian lithic assemblage mostly local pebbles of chert were used in order to produce small-sized objects. The concept of debitage mainly deals with unidirectional debitage with absent or fairly accurate management of the convexities and angles; the striking platforms are usually natural or made by one stroke. It is attested the use of both direct freehand percussion and bipolar technique on anvil in the same reduction sequence. Amongst the retouched tools the presence of two lunates is of note. This study of the Roccia San Sebastiano Uluzzian lithic complexes is significant for understanding the dynamics of the transition from Middle to Upper Palaeolithic in the Tyrrhenian margin of southern Italy.

Analysis of the Impact of Engineering Construction on the near Built Seawalls Based on PLAXIS

The article analyzes the impact of a constructing sewage treatment plant on the built seawall nearly by PLAXIS finite element software, located on the coast eastern Zhejiang. As the construction carrying on, the settlement and horizontal displacement are gradually increasing on the top and backwater slope of the seawall. The settlement on the top of Seawalls is 35.91 cm, the horizontal displacement is 50.76 cm; the settlement on the back slope is 71.45 cm, the horizontal displacement is 48.54cm. During the construction process, settlement increase rate at the foot of the backwater slope was significantly larger than that at the top of the seawalls. The horizontal displacement increase rate at the top of the seawalls was slightly larger than that at the foot of the backwater slope. The settlement and horizontal displacement of the seawall exceed the normal allowable deformation, which threatens the safety of the seawall. It is necessary to take reinforcement measures for the seawall to ensure safe operation.

Study on response characteristics of red clay slope under evaporation rainfall condition

Evaporation rainfall is one of the main causes of slope failure. Red clay belongs to special soil, and the failure mode of the slope is different from that of the general soil slope. In this paper, based on the theory of similarity simulation, a test model of red clay slope similar to the prototype is established in a certain proportion. Sensors are embedded in different positions of the slope to carry out the change rule of physical and mechanical indexes of the red clay slope under the condition of evaporation and rainfall. The results show that the water content of the slope increases during the rainfall period, the surface water content of the slope is obviously affected by the rainfall intensity, and the water content of the slope decreases in the drying period. Under the action of evaporation and rainfall, the internal temperature of slope is stable, and the surface temperature changes significantly. The pore water pressure of the top, shoulder and slope changes little with the times of evaporation and rainfall, and the pore water pressure at the foot of slope is obviously affected by evaporation and rainfall. Evaporation rainfall causes obvious horizontal displacement of red clay slope. The earth pressure increases in the rainfall period and decreases in the static and dry periods. With the increase of evaporation rainfall times, the earth pressure increases gradually.