Slope deformation partitioning and monitoring points optimization based on cluster analysis

The scientific and fair positioning of monitoring locations for surface displacement on slopes is a prerequisite for early warning and forecasting.However,there is no specific provision on how to effectively determine the number and location of monitoring points according to the actual deformation characteristics of the slope.There are still some defects in the layout of monitoring points.To this end,based on displacement data series and spatial location information of surface displacement monitoring points,by combining displacement series correlation and spatial distance influence factors,a spatial deformation correlation calculation model of slope based on clustering analysis was proposed to calculate the correlation between different monitoring points,based on which the deformation area of the slope was divided.The redundant monitoring points in each partition were eliminated based on the partition's outcome,and the overall optimal arrangement of slope monitoring points was then achieved.This method scientifically addresses the issues of slope deformation zoning and data gathering overlap.It not only eliminates human subjectivity from slope deformation zoning but also increases the efficiency and accuracy of slope monitoring.In order to verify the effectiveness of the method,a sand-mudstone interbedded CounterTilt excavation slope in the Chongqing city of China was used as the research object.Twenty-four monitoring points deployed on this slope were monitored for surface displacement for 13 months.The spatial location of the monitoring points was discussed.The results show that the proposed method of slope deformation zoning and the optimized placement of monitoring points are feasible.

High precision slope deformation monitoring model based on the GPS/Pseudolites technology in open-pit mine

As the number and geometric intensity of visual satellites are susceptible to large slopes in open-pit mines, we propose integration of GPS/Pseudolites (PLs) positioning technology which can increase the number of visible satellites, strengthen the geometric intensity of satellites and provide a precision solution for slope deformation monitoring. However, the un-modeled systematic errors are still the main limiting factors for high precision baseline solution. In order to eliminate the un-modeled systematic error, the Empirical Mode Decomposition (EMD) theory is employed. The multi-scale decomposition and reconstruction architecture are defined here on the basis of the EMD theory and the systematic error mitigation model is demonstrated as well. A standard of the scale selection for the systematic error elimination is given in terms of the mean of the accumulated standardized modes. Thereafter, the scheme of the GPS/PLs baseline solution based on the EMD is suggested. The simulation and experiment results show that the precision factors (DOP) are reduced greatly when PLs is located suitably. The proposed scheme dramatically improves the reliability of ambiguity resolution and the precision of baseline vector after systematic error being eliminated, and provides an effective model for high precision slope deformation monitoring in open-pit mine.

Deep-seated large-scale toppling failure in metamorphic rocks：a case study of the Erguxi slope in southwest China

Deep-seated large-scale toppling failure presents unique challenges in the study of natural slope deformation process in mountainous regions.An active deep-seated toppling process was identified in the Erguxi slope located in southwest China,which affected a large area and damaged critical transportation infrastructure with the volume of the deforming rock mass exceeding 24×10~6 m^3.It poses significant risks to the downstream Shiziping Hydropower Station by damming the Zagunao River.Field investigation and monitoring results indicate that the deformation of the Erguxi slope is in the advanced stage of deep-seated toppling process,with the formation of a disturbed belt but no identifiable master failure surface.It was postulated that the alternating tensile and shear strength associated with the hard/soft laminated rock strata of metasandstone and phyllite layers preclude the development of either a tensile or shear failure surface,which resulted in the continuous deformation and displacement without a catastrophic mass movement.The slope movement is in close association with the unfavorable geological conditions of the study area in addition to the construction of transportation infrastructure and the increase of the reservoir level.On the basis of the mechanism and intensity of the ongoing toppling deformation,a qualitative grading system was proposed to describe the toppling process and toevaluate the slope stability.This paper summarized the field observation and monitoring data on the toppling deformation for better characterizing its effect on the stability of the Erguxi slope.The qualitative grading system intends to provide a basis for quantitative study of large-scale deep-seated toppling process in metamorphic rocks.

Deformation features and failure mechanism of steep rock slope under the mining activities and rainfall

Underground mining activities and rainfall have potential important influence on the initiation and reactivation of the slope deformations,especially on the steep rock slope. In this paper,using the discrete element method(UDEC),numerical simulation was carried out to investigate deformation features and the failure mechanism of the steep rock slope under mining activities and rainfall. A steep rock slope numerical model was created based on a case study at the Wulong area in Chongqing city,China. Mechanical parameters of the rock mass have been determined by situ measurements and laboratory measurements. A preliminary site monitoring system has been realized,aiming at getting structure movements and stresses of unstablerock masses at the most significant discontinuities. According to the numerical model calibrated based on the monitoring data,four types of operation conditions are designed to reveal the effect of mining excavation and extreme rainfall on the deformation of the steep rock slope.

Geological analysis of gravitational rock slope deformation：a case from Nujiang River, China

This paper presents a study on the gravityinduced rock slope deformation observed along the Nujiang River in China. We performed a comprehensive field investigation and analysis to identify the deformation pattern of the slope and its triggering factors. Moreover, a geologicalevolutionary model was developed, and it considers the effects of river incision and rock mass degradation caused by weathering and simulates the mechanisms underlying the initiation and progression of the slope deformation. The results support the proposed failure mechanism in which fractures within the slope are induced by rock mass degradation caused by weathering. Importantly, the modeling reveals that compressional deformation at the toe of the slope results in a tensile failure in the upper portion of the slope, demonstrating that the rock mass in the slope toe is the key factor inducing slope deformation. This analysis of slope deformation and its spatial and temporal correlations with rock weathering and river incision reveal the main triggering factors that control the evolution of the studied slope and provide insights into the deformation process.

Analysis on velocity distribution and displacement along the profile of a slope using both empirical and analytical methods

Assessing the slope deformation is significant for landslide prediction. Many researchers have studied the slope displacement based on field data from the inclinometer in combination with complicated numerical analysis. They found that there was a shear zone above the slip surface, and they usually focused on the distribution of velocity and displacement within the shear zone. In this paper,two simple methods are proposed to analyze the distribution of displacement and velocity along the whole profile of a slope from the slip surface to the slope surface during slow movement. In the empirical method, the slope soil above the shear zone is assumed as a rigid body. Dual or triple piecewise fitting functions are empirically proposed for the distribution of velocity along the profile of a slope. In the analytical method, the slope soil is not assumed as a rigid body but as a deformable material. Continuous functions of the velocity and displacement along the profile of a slope are directly obtained by solving the Newton's equation of motion associated with the Bingham model. Using the two proposed methods respectively, the displacement and velocity along the slope profiles of three slopes are determined. A reasonable agreement between the measured data and the calculated results of the two proposed methods has been reached. In comparison with the empirical method, the analytical method would be more beneficial for slope deformation analysis in slope engineering, because the parameters are material constants in the analytical solution independent of time t, and the nonlinear viscosity of the soil can be considered.

Stability of High Slope Interbedded Strata with Low Dip Angle Constituted by Soft and Hard Rock Mass

Slopes consisting of interbedded strata of soft and hard rock mass, such as purplish red mudstone and grey brown arkosic sandstone of Jurassic age, are very common in Sichuan basin of China. The mudstone is soft while the sandstone is hard and contains many opening or closing joints with a high dip angle. Some are nearly parallel and the others are nearly decussated with the trend of the slopes. Many natural slopes are in deformation or sliding because of those reasons. The stability of cutting slopes and supporting method to be taken for their stability in civil engineering are important. In this paper, the stability and deformation of the slopes are studied. The methods of analysis and support design principle are analyzed also. Finally, the method put forward is applied to study Fengdian high cutting slope in Sichuan section of the express way from Chengdu to Shanghai. The results indicate that the method is effective.

Landslide mapping and analysis along the China-Pakistan Karakoram Highway based on SBAS-InSAR detection in 2017

The Karakoram Highway(KKH),a part of the China–Pakistan Economic Corridor(CPEC),is a major highway connecting northern Pakistan to China.The inventorying and analysis of landslides along KKH are challenging because of poor accessibility,vast study area,limited availability of ground-based datasets,and the complexity of landslide processes in the region.In order to preserve life,property,and infrastructure,and to enable the uninterrupted and efficient operation of the KKH,it is essential to strengthen measures for the prevention and control of geological disasters.In the present study,SBASInSAR(Small Baseline Subsets-Interferometric Synthetic Aperture Radar)was used to process 150 scenes of Sentinel 1-A images in the year 2017 along the Karakoram Highway.A total of 762 landslides,including 57 complex landslides,126 rock falls,167 debris slides,and 412 unstable slopes,ranging in size between 0.0017 and 10.63 km2 were identified.Moreover,this study also gains an inventory of 40 active glacier movements in this region.Landslide categorization,displacements characteristics,spatial distribution,and their relationship with various contributing factors have been successfully investigated along the entire KKH using image interpretation and frequency-area statistics.The criteria adopted for landslides categorization is presented in the study.The results showed that the 2-D ground deformation derived in Hunza valley echoes well with the general regional landslides characteristics.The spatial distribution analysis revealed that there are clumped distributions of landslides in the Gaizi,Tashkurgan,and Khunjerab in China,as well as in Hunza valley,and north of Chilas city in Pakistan.Statistical results indicated that these landslides mainly occur on south-facing slopes with a slope angle of 20°–45°and elevation relief of 550–2,100 m.Landslide development is also related to low vegetation cover and weathering effects in mountain gullies.Overall,our study provides scientific data support and theoretical references for prevention,control,and mitigation of geological disasters in the Karakoram region.

Debris flow hazard assessment by means of numerical simulations:implications for the Rotolon creek valley(Northern Italy)

On 4th November 2OLO, a debris flow detached from a large debris cover accumulated above the lowermost portion of the Rotolon landslide （Vicentine Pre-AIps, NE Italy） and channelized in the valley below within the Rotolon Creek riverbed. Such event evolved into a highly mobile and sudden debris flow, damaging some hydraulic works and putting at high risk four villages located along the creek banks. A monitoring campaign was carried out by means of a ground based radar interferometer （GB-InSAR） to evaluate any residual displacement risk in the affected area and in the undisturbed neighbouring materials. Moreover, starting from the current slope condition, a landslide runout numerical modelling was performed by means of DAN-3D code to assess the impacted areas, flow velocity, and deposit distribution of the simulated events. The rheological parameters necessary for an accurate modelling were obtained through the back analysis of the 2010 debris flow event. Back analysis was calibrated with all of the available terrain data coming from field surveys and ancillary documents, such as topographic, geomorphological and geological maps, with pre- and post-event LiDAR derived DTMs, and with orthophotos. Finally, to identify new possible future debris flow source areas as input data for the new modelling, all the obtained terrain data were reanalysed and integrated with the GB-InSAR displacement maps; consequently, new simulations were made to forecast future events. The results show that the integration of the selected modelling technique with ancillary data and radar displacement maps can be a very useful tool for managing problems related to debris flow events in the examined area.