中国建筑西南勘察设计研究院有限公司

The prediction of the soil-rock interface is crucial for airport construction in mountainous areas.Conventional methods typically rely on borehole data to directly estimate the elevation of the soil-rock interface.However,when topographic variability is pronounced and interface-elevation contrasts are large,the accuracy of such estimates is often insufficient to satisfy engineering requirements.In this paper it introduces an interpolation strategy that incorporates terrain elevation and interface depth.In this framework,the elevation of the soil-rock interface is expressed as the terrain elevation minus the depth of the interface.By shifting the prediction task to estimating interface depth alone,this approach reduces the influence of topographic variability on prediction accuracy.The performance of the proposed strategy is systematically evaluated using various prediction methods,including kernel methods such as inverse distance weighting,radial basis function kernel regression,and Gaussian process regression,as well as neural network approaches(e.g.,multilayer perceptron and Kolmogorov-Arnold Networks).Case studies from airport projects in mountainous regions demonstrate that the strategy can be readily integrated with different prediction methods and substantially improves the accuracy of soil-rock interface predictions.The findings provide technical support for airport site selection,earthwork volume estimation,and construction planning in complex terrains.

The creep characteristics of fillers in water transportation engineering are related to the long-term stability of dock foundations. However, limited studies focused on the creep model of sandstone and mudstone fillers. To construct a constitutive model that can accurately describe the creep characteristics of sandstone and mudstone fillers, shear creep tests were conducted under different mix ratio conditions. Based on experimental results, the basic model is determined, and a new fractional order creep model considering time-dependent damage is constructed by combining Riemann-Liouville fractional calculus operator theory and damage mechanics theory. Model validation analysis found that as the content of mudstone particles increases, the long-term strength of sandstone and mudstone fillers gradually decreases, promoting the development of filler damage. Sensitivity analysis reveals that the model parameters ηα1, ηα2, α1, and α2 influence the model response in descending order of sensitivity: ηα2>ηα1>α2>α1. The simulated values of the new model are consistent with the experimental data of sandstone and mudstone fillers, with an average R2 of 0.99, proving the feasibility and rationality of the new model. This achievement provides the valuable insight for understanding the creep characteristics of sandstone and mudstone fillers and the long-term stability of dock foundations.

Gypsum intercalations with uneven thicknesses are widely distributed within sand and mudstone in red layers of the Sichuan Basin.In the process of groundwater infiltration or erosion,these gypsum intercalations inevitably undergo dissolution reactions,resulting in the formation of numerous pores.Additionally,the unique physical and mechanical properties of red layers can significantly reduce the bearing capacity of foundations,leading to uneven settlement deformation and even damage to engineering structures.Therefore,it is necessary to carry out more in-depth research on the dissolution characteristics of gypsum intercalations in red layers.Based on an avionics hub project in Chongqing,this study took the original rock containing gypsum intercalations in the dam foundation as a research object.A self-designed apparatus for flowing water dissolution was used to perform the dissolution test.By regularly monitoring the changes in ion concentrations of Ca2+and SO42-ions within the solution,the dissolution process of gypsum in the test can be characterized,thereby allowing for an investigation into the erosion characteristics of gypsum intercalations in red layers under different flow velocities. At the end of the test,the gypsum intercalations in different flow velocities exhibited erosion grooves to varying degrees.Notably,the depth of surface grooves in the sample exposed to dissolution under still water conditions was the smallest,measuring only 2-3 mm,while the deepest groove formed by dissolution under flowing water conditions reached 12 mm.This observation indicates that the dissolution rate of gypsum significantly increased under flowing water conditions.Following the test,the concentrations of Ca2+and SO42-in the solution were measured,revealing that the contents of both ions showed an increasing trend over time.Comparing the dissolution test under flowing water conditions to that under still water conditions,the average chemical dissolution rate of the samples in still water was lower,both in terms of numerical values and the magnitude of changes.Furthermore,the slope of Ca2+content change curve for the experimental groups increased gradually with the rise in flow velocity,indicating that higher flow velocity has a promoting effect on the chemical dissolution of gypsum.Through the processing and conversion of the test data,it can be found that the average dissolution rate under different flow velocity conditions exhibited a rapid decline in a short time,followed by a gradual stabilization.At the initial time of the dissolution test,the average chemical dissolution rate of the samples indicated that the higher flow velocity corresponded to increased dissolution rates.With the experiment,the dissolution rate decreased rapidly and the decreasing trend under different flow velocity conditions was different to some extent.The greater the flow velocity was,the greater the dissolution rate became.The trend of curve for instantaneous chemical dissolution rate of each dissolution test group under flowing water conditions was generally consistent with the trend of curve for the average chemical dissolution rate.This trend exhibited a pattern of decline over time,with all curves demonstrating a sudden drop on the third day of the test,followed by a gradual decrease that eventually stabilized.According to the curve depicting the dissolution amount of each sample as a function of flow velocity,it is evident that both chemical dissolution and mechanical subsurface erosion in gypsum intercalations were enhanced with increasing flow velocity.

The Xianshuihe-Xiaojiang fault zone diverges into several SN-trending branch faults in central Yunnan,among which the Puduhe fault has triggered earthquakes of magnitude more than 5 for many times,but its spatial distribution characteristics of tectonic activity are not clear.Because geomorphic index is very sensitive to tectonic activity,it can well indicate the distribution characteristics of tectonic activity.In order to study the distribution characteristics of tectonic activity of the Purduhe fault,41 basins in the Purduhe fault region were extracted by using digital elevation model(DEM)with a resolution of 30 m.The basin is divided into three sections:north section(Sayingpan-Fumin Section),middle section(Fumin-Jinning Section)and south section(Jinning-Eshan Section).Seven geomorphic indices including hypsometric curve and hypsometric integral(HI),asymmetric factor(AF),basin shape index(BS),the ratio of valley floor width to valley height(VF),normalized stream-length gradient(SLK),sinuosity of the mountain front(Smf)and the steepness index(Ksn)were obtained through analysis.The results show that the spatial variation characteristics of geomorphic indices of the Puduhe fault are not affected by non-structural factors(precipitation and lithology),but they are mainly affected by tectonic activities.The relative tectonic activity of the Puduhe fault gradually decreases from north to south,and the tectonic activity of the east side of the fault is slightly weaker than that of the west side.The structural activity of the Puduhe fault is weaker than that of the Xiaojiang fault,indicating that during the extrusion process of the Sichuan-Yunnan block,the highly active area is mainly concentrated in the boundary fault zone.

There are frequent cataclastic rockfall disasters in southwest mountainous areas.To accurately simulate the process of rockfall movement and quantify the risk of rockfall,it must first determine the volume of rockfall.However,to date,there is no effective and reliable method to estimate the volume of rockfall.This study constructed an effective method of estimating cataclastic rock rockfall volume based on image recognition.The application and verification of this method was conducted at the rockfall of Yaohe Dam in Shimian of Yaxi Expressway in 2020.Through in-site measurement and close photogrammetry of UAV,the partition and sampling area of rockfall accumulation area are determined.Using the open-source software of image processing(ImagePy),a quick block identification step is established,and characteristic parameters,such as equivalent particle size,perimeter,and area of blocks,are extracted.The method of estimating the volume of cataclastic rock rockfall based on the volume distribution of blocks was applied and verified by rock rockfall in the field.The results show that:(1)ImagePy software has high speed and accuracy in block image recognition;(2)The obtained distribution curve of rock volume is nearly consistent with that measured in the field;(3)The estimated volume of rock rockfall in Yaohe Dam accounts for nearly 80％of the volume obtained by three-dimensional point-cloud difference method.Thus,it is feasible to use image recognition technology to extract the particle size and estimate the size of cataclastic rock mass,and it has the advantages of high efficiency and accuracy.This method can be applied to rapid assessment of cataclastic rock mass and quantitative risk assessment.Statistical block volume distribution can provide data support for fragmentation research.