Morphology and controlling factors of the longitudinal profile of gullies in the Yuanmou dry-hot valley

The morphology of the gully longitudinal profile （GLP） is an important topographic index of the gully bottom associated with the evolution of the gullies. This index can be used to predict the development trend and evaluate the eroded volumes and soil losses by gullying. To depict the morphology of GLP and understand its controlling factors, the Global Positioning System Real-time Kinematic （GPS RTK） and the total station were used to measure the detail points along the gully bottom of 122 gullies at six sites of the Yuanmou dry-hot Valley. Then, nine parameters including length （Lt）, horizontal distance （Dh）, height （H）, vertical erosional area （A）, vertical curvature （Co）, concavity （Ca）, average gradient （Ga）, gully length-gradient index （GL）, normalized gully length-gradient index （Ngl）, were calculated and mapped using CASS, Excel and SPSS. The results showed that this study area is dominated by slightly concave and medium gradient GLPs, and the lithology of most gullies is sandstone and siltstone. Although different types of GLPs appear at different sites, all parameters present a positively skewed distribution. There are relatively strong correlations between several parameters： namely Lt and H, Dh and H, Lt and A, Dh and A, H and GL. Most GLPs, except three, have a best fit of exponential functions with quasi- straight shapes. Soil properties, vegetation coverage, piping erosion and topography are important factors to affect the GLP morphology. This study provides useful insight into the knowledge of GLP morphology and its influential factors that are of critical importance to prevent and control gully erosion.

Analysis of Longitudinal Profiles along the Eastern Margin of the Qinghai-Tibetan Plateau

Resulting from the collision of the Eurasian and Indian plates, the Qinghai-Tibetan Plateau is commonly known as the ＇roof of the world＇. Collectively the Yarlung Tsangpo, Nu, Laneang, Yangtze, Yalong, and Yellow River basins drain the eastern margin of the plateau. In this paper, we utilize Shuttle Radar Topography Mission elevation data to examine morphometric and relief attributes of these basins to reveal insights rates of incision. A robust into tectonic activity and technique using Maflab is proposed to alleviate errors associated with SRTM data in the derivation of river longitudinal profiles. Convex longitudinal profiles are interpreted to be a product of uplift rates that exceed rates of channel incision along the entire margin of the Qinghai- Tibetan Plateau. Highest relief towards the south reflects extensive fluvial incision. High relief is also prominent along major active faults. Erosion patterns are related to distance from knickpoints. Highest rates of erosion and incision are evident towards the south, with decreasing values towards the north, suggesting a link between tectonic activity and erosion.

Application of River Longitudinal Profile Morphometrics to Reveal the Uplift of Lushan Mountain

The stream power model was applied to Lushan Mt. in South China in order to verify its capability of interpreting the uplift of a small block mountain. On a log-log plot, the longitudinal profiles of 9 rivers derived from a 30 m DEM exhibit primary characteristics similar to those derived from a 5 m DEM; however, the 5 m DEM clearly reveals more minor knickpoints, and the positions of knickpoints are pinpointed more accurately. All of the studied rivers on the block mountain are in a transient state due to geological perturbations. Some of them exhibit two segments in steady state separated by a slopebreak knickpoint. Such rivers generally develop in a longitudinal valley, which are less perturbed by substrate inhomogeneities. The similar heights of the slope-break knickpoints and the similar uplift rate indicated by the k_（sn） values demonstrate an almost simultaneous headward erosion induced by the fall in base level. This modelling result is consistent with the mode of formation of this particular block mountain. Our study demonstrates that the stream power model is applicable to a small tectonicallyactive massif only if the channel segments are in a steady state.

The methods and program implementation for river longitudinal profile analysis——RiverProAnalysis, a set of open-source functions based on the Matlab platform

River is one of the geomorphic units that are the most sensitive to tectonic activity, of which the longitudinal profile serves as a key archieve to record information on active tectonics. The stream-power incision model is an important means to analyze channel long profiles and to extract both temporal and spatial patterns of regional tectonic activity. Analytical solutions to the steady-state and linear transient-state equations of the model provides means to calibrate drainage basin concavity,calculate channel steepness index, determine drainage divide stability, project the paleo-channel profile, and to invert the tectonic uplift rate history. Yet, not all of these functions have been implemented in the published open-source tools. Here, we developed a set of open-source codes, RiverProAnalysis, which was based on the Matlab platform and integrated all of these functions. The products of the tool set are in the format of image, text and vector files, which not only can be used for visual analysis, but be read by softwares of geographic information system. Taking examples of two transient drainage catchments in the northern margin of the Taiyuan Basin, we analyzed the long profiles of the trunk streams, identified two generations of knickpoints, and estimated the minimum amount of river incision. We combined all the trunk and tributary channels together to model the catchment-wide uplift history and found moderate increases in the uplift rates since the Middle Pliocene and rapid accelation since the late Quaternary. The inverted results are consistent with the sedimentary records in the adjacent basin. By comparing the chi value,slope, and topographic relief of both sides of the catchment divide, we concluded the stability of the drainage divide. Our tool set integrates the main functions of the modern studies on fluvial landsape, thus providing a powerful tool for analyzing river long profiles and for understanding tectonic geomorphology.

Longitudinal profiled plate straightening process based on curvature integral method

Considering the variable cross section thickness of longitudinal profiled plate and the dynamic reductions of straightening rolls,an analytical model combining curvature integral method with linear decreasing straightening scheme was proposed to investigate the longitudinal profiled plate straightening process.Moreover,the calculation flow and solution algorithm of longitudinal profiled plate straightening process were presented.To verify the proposed model,calculated straightening forces were compared with the measured values,and very good agreements were achieved.Then,the reduction,contact angle,reverse bending curvature,residual curvature,straightening force and straightening moment of longitudinal profiled plate in the straightening process were calculated and analyzed,and the calculated results show that the curvature integral method can be used to reveal the mechanism of longitudinal profiled plate straightening.

Analytical algorithm for longitudinal deformation profile of a deep tunnel

To investigate the longitudinal deformation profile(LDP)of a deep tunnel in non-hydrostatic condition,an analytical model is proposed in our study.In this model,the problem is considered as a superposition of two partial models,and the displacement field of the second partial model is the same as that of the concerned problem.Therefore,the problem can be solved by a model with simple boundary conditions.We obtain the solutions for the stress and displacement fields of an infinite body caused by arbitrary surface tractions on the boundary of the coming tunnel(zone inside the tunnel before excavation)by integrating the extended Kelvin solution over the boundary.The obtained stress solution is used to solve the specific surface tractions,which can satisfy the boundary conditions of the second partial model,on the boundary of the coming tunnel in an infinite body.Then,the specific surface tractions are substituted into the obtained displacement solution to solve the displacement on the wall and face of the tunnel.Therefore,the LDP can also be calculated.The proposed solution is verified by both numerical simulation and the LDP functions recommended by other researchers.The major advantage of our analytical model is that it can consider the effects of the axial and horizontal lateral pressure coefficients.It is revealed that the horizontal lateral pressure coefficient majorly affects the LDP behind the tunnel face,while the axial lateral pressure coefficient dominates the LDP ahead of the tunnel face.Furthermore,the deformation characteristics of the LDPs ahead of the face and the unexcavated core are investigated.The axial displacements of the excavation face can be used to predict the crown displacements ahead of the face.

Estimating Mechanical Parameters of Hydrate-Bearing Sediments on Basis of Shear Wave Velocity Under Triaxial Compression

The strength parameters of hydrate-bearing sediments(HBS)are vital to geological risk assessment and control during drilling and production operations.However,current publications mainly focus on the laboratory evaluation of strength parameters through triaxial compression,generating results intrinsically deviating from those obtained through petrophysical modeling.In this study,we developed an integrated apparatus that can simultaneously measure wave velocity and the mechanical behaviors of HBS under triaxial compression conditions.A series of experiments were conducted to analyze correlations between wave velocities and strength parameters.Results reveal that the P-and S-wave velocities considerably increase with hydrate saturation and are affected by effective confining pressure.Failure strength and elastic modulus are correlated with P-wave velocity.Finally,semi-empirical models are developed to predict strength parameters based on P-wave velocity and extended to establish longitudinal profiles for strength parameters of hydrate reservoirs in the Nankai Trough.This study offers insights into the acoustic properties of HBS under stress states for the prediction of mechanical parameters during natural gas hydrate development.

A model for the mean velocity of debris flow movement based on the minimum energy dissipation principle

The geomorphic minimum energy dissipation principle is important in the development of gully evolutionary theory.The impact of debris flows on channels during movement also adheres to this theory.A minimum energy dissipation model for debris flows has been obtained from previous studies,which is derived from the flow rules of runoff along a channel under rainfall or ice-snow meltwater conditions.However,the lack of consideration for erosion characteristics has hindered a comprehensive understanding of the movement characteristics of debris flow.In this paper,the phenomenon of volume increase resulting from the entrainment along debris flow movement is considered in order to derive a model for the mean velocity,reflecting the minimum energy dissipation principle.The entire expression of the mean velocity model is determined through 38 typical glacial and rainstorm debris flow cases.To evaluate the reliability of the proposed model,we employed 164 monitoring data from 1995 to 2000 in the Jiangjia gully,Yunnan,China.The results show that the velocity calculated by the proposed model are highly correlated with those obtained from the monitoring data.Additionally,a comparison is made between the mean velocities calculated by the proposed model and those obtained from previous studies,highlighting the exceptional applicability of the proposed model.This study will contribute to reveal the movement laws of debris flow along the channel.

Controls on geomorphic characteristics of the Xiaohei River basin in the upper Lancang-Mekong, China

Understanding the evolution of the fluvial geomorphology in an orogenic belt provides valuable insight into the relationship between upper crustal deformation and surface processes.The upper Lancang-Mekong River is in an area experiencing both uplift and erosion.The related processes provide a steady sediment supply to the lower reaches of the river and play an important role in the regional environmental changes.The Xiaohei(Weiyuan)River Basin is an important sub-basin in this area,which is characterized by large-scale topographic fluctuations,active tectonics and erosion,and anthropogenic activities.These different factors introduce numerous complexities to the local surface processes.In this study,we investigate and quantify the controls of geomorphic evolution of the Xiaohei River Basin.We located and mapped the main knick-zones within the channels and examined the main genetic factors,such as faults and stratigraphic differences.The results show that the areas with the lowest uplift rates are characterized by a low steepness index and are located in the southeastern part of the basin.The stream power of the mainstream increases downstream,with an average value of^122 W/m.The erosional activity of the various stream channels is intense.Overall,the basin tends to expansion,with only local instances of inward contraction.Our analysis confirms that a number of the geomorphic evolutionary characteristics of the Xiaohei River Basin are transient.In addition,the future potential for the increasing the number of dams and the hydropower development in the basin may weaken the expansion trend of the basin over a long period of time.

Geomorphic effect of debris-flow sediments on the Min River,Wenchuan Earthquake region,western China

Coseismic landslides and subsequent mobilization of sediment greatly aggravated the landscape evolution and river sedimentation after the Wenchuan earthquake.The debris-flow alluvial fan and river morphological index was combined to describe quantitatively the effects of debris-flow sediment on the river characteristics in Longmen Mountains.The section of the Min River from the urban area of the Wenchuan county to the epicenter,the Yingxiu town in this county,was selected as the study area.We identified 27 river-blocking debrisflows(5 partial-,7 semi-,7 over semi-,and 5 fullyblocking degrees)in the study area via remote sensing interpretation and field survey.Based on this,the response of river longitudinal profile and curvature to debris-flow sediment was qualitatively and quantitatively analyzed.The results show that the channel gradient has decreased due to debris-flow aggradation,while two marked peaks in the river steepness index(ksn,represents the relative steepness degree of the channel)changed from 585 m0.9 to 732 m0.9 in zone 1,from 362 m0.9 to 513 m0.9 in zone 2.Moreover,the main channel has undergone substantial lateral migration with channel width decreased and river curvature increased.The temporal and spatial variation between river morphological characteristics and debris-flow sediments in short-term provides insights into the internal dynamic role of mass wasting processes in river morphology,which could be served as useful information for natural hazards management to prevent the river from being blocked by episodically debris flows after the earthquake.

Geomorphological responses of rivers to active tectonics along the Siwalik Hills,Midwestern Nepalese Himalaya

The Nepalese Himalaya is well known for ongoing collisional tectonics,witnessed by major historical and recent earthquakes.The Siwalik Hills in Midwestern Nepalese Himalaya are bounded by eastwest trending Main Frontal Thrust(MFT)to the south and the Main Boundary Thrust(MBT)to the north.The area is dissected by numerous southwest to south-flowing bedrock rivers.This study investigates geomorphic metrics of these rivers to unravel landscape evolution and active tectonics of the Siwalik Hills.Digital Elevation Model(DEM)analysis was conducted to extract structural lineaments and longitudinal river profile and their metrics(knickpoints,Normalized Steepness Index(ksn),concavity index,and chi integral)using steam powerlaw approaches.Most of the lineaments trend eastwest like MFT.River profiles exhibit convex to double-concave shapes with upstream-propagating tectonic knickpoints that separate upstream and downstream reaches,indicating different phases of river incision.The spatial distribution of ksn shows high values along with low concavity values at the eastern part of the study area,reflecting disequilibrium conditions that are likely responding to a high uplift rate.Chi integral distribution shows a variation in drainage divide migration between the eastern and western parts of the study area.This study suggests that the rivers in the Siwalik Hills are undergoing active incision likely related to the ongoing uplift and active deformation associated with the Himalayan tectonics.The above findings can bring fresh perspectives to comprehend the neotectonic deformation and lateral variability along the Siwalik Hills landscapes within the Himalaya.

Physical model simulation of rock-support interaction for the tunnel in squeezing ground

The existence of squeezing ground conditions can lead to significant challenges in designing an adequate support system for tunnels.Numerous empirical,observational and analytical methods have been suggested over the years to design support systems in squeezing ground conditions,but all of them have some limitations.In this study,a novel experimental setup having physical model for simulating the tunnel boring machine(TBM)excavation and support installation process in squeezing clay-rich rocks is developed.The observations are made to understand better the interaction between the support and the squeezing ground.The physical model included a large true-triaxial cell,a miniature TBM,laboratoryprepared synthetic test specimen with properties similar to natural mudstone,and an instrumented cylindrical aluminum support system.Experiments were conducted at realistic in situ stress levels to study the time-dependent three-dimensional tunnel support convergence.The tunnel was excavated using the miniature TBM in the cubical rock specimen loaded in the true-triaxial cell,after which the support was installed.The confining stress was then increased in stages to values greater than the rock’s unconfined compressive strength.A model for the time-dependent longitudinal displacement profile(LDP)for the supported tunnel was proposed using the tunnel convergence measurements at different times and stress levels.The LDP formulation was then compared with the unsupported model to calculate the squeezing amount carried by the support.The increase in thrust in the support was backcalculated from an analytical solution with the assumption of linear elastic support.Based on the test results and case studies,a recommendation to optimize the support requirement for tunnels in squeezing ground is proposed.

NUMERICAL MODELING OF CHANNEL EQUILIBRIUM PROFILE AND ITS EFFECT ON FLOOD CONTROL

Based on the morphology of Luoshan-Hankou reach at the middle Yangtze River, the one-dimensional, unsteady flow and sediment transport numerical model was adopted to study the generalized cha nnel equilibrium profile. The variation of the longitudinal equilibrium profile, and the r elation with the condition of the inflow water and sediment from the upper reach were analyzed. Meanwhile, the numerical simulation results were compared with t he corresponding theoretical results. Finally, the equilibrium longitudinal slop e variations and its impact on flood control were analyzed after the sediment tr ansport process has changed.

Evaluation of the Relative Tectonic Activity from the Faults in the Gengma-Lancang-Menghai Seismic Belt(Southwestern China)

The Gengma-Lancang-Menghai seismic belt,the southernmost part of the North-South seismic belt,is controlled by four active faults:the Nantinghe fault(NTHF),the Sanjianshan fault(SJSF),the Hanmuba-Lancang fault(HMB-LCF),and the Heihe fault(HHF),from northwest to southeast.However,the tectonic activity of the faults in the Gengma-Lancang-Menghai seismic belt has not been fully studied yet.In the present work,we conducted tectonic geomorphic indices to analyze the relative tectonic activity along the faults in the seismic belt based on the digital elevation model.We interpreted asymmetric factor,index of drainage basin shape,hypsometric integral,normalized streamlength gradient,valley floor-to-width to height ratio,and longitudinal profiles to show that the relative tectonic activity is higher in the north and lower in the south,and is strong in the region from Shanjia to Huimin in the center of the seismic belt.

Prospects for Variable Gauge Rolling:Technology,Theory and Application

Variable gauge rolling （VGR） is a new technology to produce flat products with different thicknesses （FDT）, which could be used to replace conventional fiat products in order to save metals and reduce structure mass. The method of VGR was introduced for investigating new problems in rolling theory of VGR, and the new formulas for calculating parameters of VGR were proposed. Besides, some results of numerical simulation by finite elemen~ method were described. As an example, the products applications of FDT in bridge construction, ship building and auto manufacturing were presented. Finally, the prospects for VGR and FDT were discussed.

Recent Development on Theory and Application of Variable Gauge Rolling, a Review

Variable gauge rolling （VGR） is a new technology for producing the materials which have the advantage of lightweight due to optimized thickness according to load distribution. The new progresses in the theoretical research and application of VGR are reviewed in this paper. Two basic equations, VGR-f and VGR-s, were deduced. The former is a new differential equation of force equilibrium, and the latter is a new form of formula for the law of mass conservation. Both of them provide a new base for the development of VGR analysis. As the examples of VGR＇s application, tailor rolled blank （TRB） and longitudinal profile （LP） plate are introduced. Now TRBs are only produced in Germany and China, and have been used in the automotive manufacturing to play an important role in lightweight design. LP plates have been used in shipbuilding and bridge construction, and promised a bright prospect in reducing construction weight. In addition, new technologies and applications of VGR emerge constantly. Tailor welded strips and tailor rolled strips with variable thickness across the width can be used for progressive die and roll forming. The 3D profiled blank can be obtained by two-step rolling process. Tailor tubes witli the variable wail thickness are an efficient way to reduce the weight. The blank with tailored thickness and mechanical property is also under development. Above products based on the tailored ideas provide a new materials-warehouse for the designers to select so as to meet the needs of weight reducing and material saving.

Morphometric and geological conditions for sediment accumulation in the Udava River, Outer Carpathians, Slovakia

The accumulation of sediment in river channels is a phenomenon that is not only influenced by the channel morphology, but also by the physical and geographical character- istics and the endogenous and exogenous processes taking place in the catchment. This paper presents an analysis of the impact the changes in lithological conditions have on the morphological and morphometric parameters of the Udava River channel and their relation to the channel accumulation forms representative of the river＇s longitudinal profile as well as of its planform. Results document when accumulation forms occur and what is their spatial dis- tribution within the longitudinal and cross-sectional river profiles. More resistant structures created sections with a lower degree of sedimentation, while in depression segments the degree of sedimentation was higher. With the increase in longitudinal slope, the impact of channel width on the average channel bar size increased. Also a difference in the accumula- tion was observed between the left and right bank which could be possibly explained by the impact of Coriolis force.