Geological Topography Research Articles

Analysis of Seismic Response of the Arch Bridge across Reservoir considering Fluid-Solid Coupling Effect

Most of the deep-water bridges in Chinese reservoirs are concentrated on rivers in the southwest region. The unique structural characteristics of arch bridges are more in line with the geological topography requirements of deep reservoir areas, making them the bridge type of choice for bridges in deep reservoir areas. While the southwest region is an earthquake-prone area, in order to study the safety of arch bridges across deep water in the reservoir area, it is necessary to analyze the effect of water under seismic behavior on the box section arch ring and explore the effect of arch inundation depth on the dynamic response of arch bridges in the reservoir area. In this study, the effect of fluid-solid coupling is considered, the modified Morison equation is used to calculate the hydrodynamic pressure, and the effect of arch bridge inundation depth on the dynamic response is analyzed based on the Midas/civil finite element model of the arch bridge in the Yunnan reservoir area. The results show that the seismic response of the arch bridge across the reservoir is greatly influenced by the submergence depth of the arch bridge due to the fluid-solid coupling effect, and the influence of the hydrodynamic pressure on the longitudinal moment (My) and transverse moment (Mz) of the arch bridge increases with the increase of the submergence depth. There is a threshold value of the submergence depth. When the submergence depth is less than the threshold, the effect of fluid-solid coupling is negligible, and when the submergence depth is greater than the threshold, the fluid-solid coupling effect is significant. The thresholds for different parts of the main arch ring are different. The most unfavorable water depth in different parts of the main arch ring is not necessarily the water depth when the arch ring is completely submerged. Based on this result, for reservoir arch bridges in high intensity areas, it is recommended that the inundation depth of arch bridges crossing deep water reservoirs should be h/f less than or equal to 5/8 f.

Dense cold-water coral garden of Paragorgia johnsoni suggests the importance of the Mid-Atlantic Ridge for deep-sea biodiversity.

Mid‐ocean ridges generate a myriad of physical oceanographic processes that favor the supply of food and nutrients to suspension‐ and filter‐feeding organisms, such as cold‐water corals and deep‐sea sponges. However, the pioneering work conducted along the Mid‐Atlantic Ridge failed to report the presence of large and dense living coral reefs, coral gardens, or sponge aggregations. Here, we describe the densest, near‐natural, and novel octocoral garden composed of large red and white colonies of Paragorgia johnsoni Gray, 1862 discovered at 545–595 m depth on the slopes of the Mid‐Atlantic Ridge, in the Azores region. This newly discovered octocoral garden is a good candidate for protection since it fits many of the FAO criteria that define what constitutes a Vulnerable Marine Ecosystem. The observations described here corroborate the existence of a close relationship between the octocoral structure and the ambient currents on ridge‐like topographies, providing new insights into the functioning of mid‐ocean ridges' ecosystems. The ubiquitous presence of biogenic and geological topographies associated with mid‐ocean ridges, which could act as climate refugia, suggests their global importance for deep‐sea biodiversity. A better understanding of the processes involved is, therefore, required. Our observations may inspire future deep‐sea research initiatives to narrow existing knowledge gaps of biophysical connections with benthic fauna at small spatial scales along mid‐ocean ridges.

The effect of Hengduan Mountains Region (HMR) uplift to environmental changes in the HMR and its eastern adjacent area: Tracing the evolutionary history of Allium section Sikkimensia (Amaryllidaceae)

Exploring the effects of orographic events and climatic shifts on geographic distribution of organism in the Hengduan Mountains Region (HMR) and its eastern adjacent area is crucial to the understanding of the environmental changes to organismal evolution. To gain further insight into these processes, we reconstruct evolutionary history of ten species in Allium section Sikkimensia, distributed across regions abovementioned. Using chloroplast and nuclear sequence variation of 79 populations of these ten Allium species with known morphological preferences, we elucidate the phylogenetic relationship, divergence time, ancestral area and genetic structures. Climatic variables analysis, Isolation by distance (IBD) and environment (IBE) and Species distribution modeling (SDM) were analyzed along different genetic clades. These analyses indicated that the initial split of Sikkimensia was triggered by climate changes following Qinghai-Tibet Plateau sensu lato (QTPsl) uplift during the late Miocene. Subsequently, divergences within lineage (lineage A)/among lineages (lineage C and D) in Sikkimensia may be induced by the intense uplift of the HMR around 3–4 Ma and abrupt intensifying of the Asian monsoon regimes. Furthermore, Sikkimensia populations exhibited lopsided demographic history in the Last Glacial Maximum (LGM), as was indicated by the expansion of their range in the QDM and contraction in the HMR. Our findings appear to suggest that the HMR uplift could have strengthened the orographic difference between the HMR and its eastern adjacent area and led to a colder climate in the HMR, while geological topography also played an important role for taxa to respond the climate change that had taken place in the HMR and its eastern adjacent area during the Pleistocene.

Discriminating between the roles of late Pleistocene palaeodischarge and geological‐topographic inheritance in fluvial longitudinal profile and channel development

AbstractThis paper investigates the influences of palaeohydrology and geological‐topographic inheritance in shaping the channel of the lower River Suir, southeast Ireland. Results of acoustic surveys of the lower River Suir and Waterford Harbour reveal two scales of pseudo‐cyclic river bedforms. Longitudinal elevation profiles of the geological topography (undulating bedrock and till‐mantled bedrock) bounding the present floodplain swath reveal pseudo‐cyclicity in that terrain too. Spectral and statistical analyses are used to quantify the cyclicity of the long profile and geological‐topographic series. These methods show that the dominant cyclicity of the long profile reflects autocorrelation more than inheritance of cyclicity from the bounding geological topography. The cyclicity of the long profile mainly reflects a hydraulic control on pool‐spacing, although some cyclicity probably has been inherited from the geological‐topography. Channel‐forming palaeodischarge is estimated based on the dominant pool‐spacing revealed by spectral analysis, validated using relationships between meander wavelength, channel cross‐sectional geometry and hydraulically‐informed discharge reconstruction. The palaeodischarge estimates are in close agreement and are two orders of magnitude greater than present flood maxima. Significantly, these palaeodischarge estimates also agree closely with palaeodischarge calculated for the submerged Pleistocene palaeochannel that extends across the near‐shore continental shelf from Waterford Harbour. The pool‐sequence of the lower Suir and the submerged palaeochannel represent a former land‐system that was active during a period of low relative sea level during the last glacial. More broadly, the paper offers insights into the landscape evolution of formerly glaciated regions that experienced very wide discharge variability during and after the transition from glacial to interglacial regimes, in a context of complex relative sea level change. Copyright © 2017 John Wiley & Sons, Ltd.

Ecosystem engineering creates a direct nutritional link between 600-m deep cold-water coral mounds and surface productivity.

Cold-water corals (CWCs) form large mounds on the seafloor that are hotspots of biodiversity in the deep sea, but it remains enigmatic how CWCs can thrive in this food-limited environment. Here, we infer from model simulations that the interaction between tidal currents and CWC-formed mounds induces downwelling events of surface water that brings organic matter to 600-m deep CWCs. This positive feedback between CWC growth on carbonate mounds and enhanced food supply is essential for their sustenance in the deep sea and represents an example of ecosystem engineering of unparalleled magnitude. This ’topographically-enhanced carbon pump’ leaks organic matter that settles at greater depths. The ubiquitous presence of biogenic and geological topographies along ocean margins suggests that carbon sequestration through this pump is of global importance. These results indicate that enhanced stratification and lower surface productivity, both expected consequences of climate change, may negatively impact the energy balance of CWCs.

High Containing Fly Ash Grouting Material Performance Test of Large Channel Underlying Goaf

Middle route of South-to-North Water Transfer Project of Yuzhou section of the mined-out area of coal mining area is old, has the characteristics of small coal mine of irregular, no mine distribution, engineering geological conditions are very complicated, decided to adopt the filling grouting treatment after analysis. Because the goaf filling grouting treatment scope, size, slurry material costs become an important factor restricting the engineering project management, and setting strength and fineness requirements of grouting material is relatively low, overall consideration the mined-out geology topography and distribution characteristics, combines with the highway, railway and other treatment of research results of mined-out area, comes up with the cement grout high containing 85% fly ash filling grouting, and provides valuable experience for similar goaf.

Comparisons of Random Forest and Support Vector Machine for Predicting Blasting Vibration Characteristic Parameters

The prediction of blasting vibration characteristic parameters is very important to evaluate the situations of blasting vibration damage. Blasting vibration of rock mass is affected by lots of characteristics, such as charging parameter, rock type and geological topography. The characteristics should be comprehensively considered in order to accurately predict the blasting vibration. Based on training and testing 93 sets of measured data in an open-pit mine, Support Vector Machine (SVM) and Random Forest (RF) methods are applied to predict the peak particle velocity (PPV), first dominant frequency and duration time of first dominant frequency of blasting vibration. The other 15 groups of measured data are tested as forecast samples, of which the predicted results are consistent with the measured ones. Results show that the prediction accuracies of SVM and RF models were acceptable. The average error rate of SVM is lower than results using RF, and the weight of factors is determined using RF. It is a new approach to predict destructive effect on housing under blasting vibration using SVM and RF, which can be applied to practical engineering.

Organic matter dynamics control plant species coexistence in a tropical peat swamp forest

We studied the relationship between the coexistence of tree species and the dynamics of organic matter in forests. A tropical peat swamp forest was selected as a model ecosystem, where abiotic factors, such as geological topography or parent rock types, are homogeneous and only biological processes create habitat heterogeneity. The temporal or spatial variation of the ground elevation of peat soils is mainly caused by changes in the balance between organic matter inputs to soils and decomposition, which is affected by the growth and death of influential trees. To clarify the processes of elevation dynamics, we measured the microtopography around some tree groups, estimated organic matter (in the form of litter and roots) in soils under three kinds of microtopographic conditions, measured decomposition rates and detected dominant species' shifting distribution patterns in different stages of growth in relation to the locations of tree groups creating specific microtopographic conditions. We found that growth or death of buttressed trees has the greatest effects on the rising or sinking of ground surfaces through changes in litter supply and root production. We discuss here the possibility of extending our model to other forest types.

A colour-map plugin for the open source, Java based, image processing package, ImageJ

We present an interactive approach to the pseudo-colouring of greyscale images. We implement the technique by computing mappings from a three- dimensional (3D) colour space to a one- dimensional greyscale space (i.e. R 3 to R). To compute our maps, we employ both linear and nonlinear interpolation in 3D colour space. We validate our work by applying our maps to greyscale images resulting in significant image enhancement. Applications include space imagery, geological topographies, medical scans and many more. Our tool is coded as a Java plug-in for the open source image processing package, ImageJ.

Group Velocity Rayleigh Wave in Chinese Continent and its Adjacent Seas

AbstractRayleigh waves are used to carry out tomographic inversion and obtain group velocity for a period range from 15 s to 120 s in East Asia (70°E–145°E, 10°N–55°N). The Tarim Basin is obviously recognizable for the period of 15s appearing as a low‐velocity region, however, it can not be seen for 16 s–33 s periods, and then appears as a high velocity zone for 36s–85s periods. This suggests that there exists a deep root under the Tarim Basin. With clear demarcation lines to the Indian plate on the south and to the Tarim Basin and Qaidam Basin on the north, Qinghai‐Xizang Plateau is the most prominent low velocity block for periods of 44 s–120 s, and the velocity in its central and western portion is lower than that in the east. In the vicinity of Chiang Mai, Thailand, we can see a low velocity block with a scale of 1 000 km, which may be created as the mass of Qinghai‐Xizang Plateau migrates southeast. The South‐North seismic belt appears to be a region with high group velocity gradient. The velocities in the east part are noticeably higher than that in the west part. The central of South China Sea, the Japan Sea, and Philippine Sea appear as oceanic crust. The image of Philippine Sea is completely consistent with the geological topography and the seismic zone. Around the Philippine Sea and the Japan Sea, there is a low velocity belt about 400km wide, which may be a zone with magmatic activities.

Geological Topography and Thronging Species by Gill Net Fisheries at Souma, Fukushima

Geological Topography and Thronging Species by Gill Net Fisheries at Souma, Fukushima

A New Method to Express The Suitability-of Building Site from View Point of Geology Topography and Soil Condition.

The selection of building site is the most important work for engineer in stage of planning. Resently many failures of building site occur at the foot of mountain and hill region.Most of them seem to be coused by inadequate condition of the site. When we select the building site, we usually examine rather empirically several factors such as geological topographical hydrological and soil condition.The project being comparatively small and limited, engineer is able to analize stable condition by appling of soil mechanics principle. But the area conserved having great extention and variety, we must treat many factors affecting the stability of the site as geology topography soil sight view, traffic condition etc.We have hitherto treated these factors empirically and fragmentally. Now in this paper we propose a new method to express these factors more rationally than before.The factors treated in this paper are limited in geological topographical and soil condition and they are replaced into a standard term suitability index which is calculated by soil mechanics principle.The suitability index being a function of soil and rock properties (c, φ) and gradient of the slope (θ) means possible maximum width of even site plane that is formed by cutting and banking of soil or rock.Thus the factors discussed fragmentally before are comparatively synthetic expressed. This method however is not available for exact analysis of stability of relatively small and limited site because the stability of the site is affected considerably by another local minor factors.This method therefore is valuable as a standard to determine adequate site in primary stage of site planning.