scholarly journals Systematic slope stability assessment through deformation field monitoring

2019 ◽  
Vol 92 ◽  
pp. 18009
Author(s):  
Yukun Wei ◽  
Anders B. Lundberg ◽  
Fredrik Resare

Field monitoring is frequently carried out during excavations and other geotechnical activities and provides additional information during the execution of a construction project. The interpretation of field monitoring data is often obscured by measurement noise and disturbance, and a systematic approach to assess both the quality and implications of the field monitoring data is very helpful in geotechnical practice. The possibility to infer practical conclusions from the field monitoring data depends on the type of field measurements, especially in monitoring of the stability of slopes. Pore pressure measurements can serve as a direct measurement of utilized soil strength for a slope, while deformation measurements are significantly more ambiguous and complicates the interpretation. The assessment of slope stability through field monitoring of deformations requires inverse or back analysis of the soil properties, followed by a forward analysis of the resulting slope stability. Such an inverse or back analysis is frequently influenced by non-uniqueness of the material properties and the stability of the measurement data. Systematic approaches to inverse or back analysis have been demonstrated in the scientific literature, but the practical use of these methods is not entirely straight-forward. The current paper presents a case study of systematic slope stability assessment through field measurements of deformations with a review of the field monitoring programme, numerical simulations of deformations, and a simplified approach to back analysis of the soil parameters. The excavation of a slope in an urban environment including layers of organic clay covered with highly heterogeneous gravel fill is used as an example of geotechnical back analysis. The aim is to elucidate some of the challenges in geotechnical back analysis while providing some practical solutions for practice.

2020 ◽  
pp. 65-75
Author(s):  
Liudmyla Skochko ◽  
Viktor Nosenko ◽  
Vasyl Pidlutskyi ◽  
Oleksandr Gavryliuk

The stability of the slope in the existing and design provisions is investigated, the constructive decisions of retaining walls on protection of the territory of construction of a residential complex in a zone of a slope are substantiated. The stability of the slope when using rational landslide structures is estimated. The results of the calculation of the slope stability for five characteristic sections on the basis of engineering-geological survey are analyzed. For each of the given sections the finite-element scheme according to the last data on change of a relief is created. The slope was formed artificially by filling the existing ravine with construction debris from the demolition of old houses and from the excavation of ditches for the first houses of the complex. Five sections along the slope are considered and its stability in the natural state and design positions is determined. Also the constructive decisions of retaining walls on protection of the territory of construction of a residential complex as along the slope there are bulk soils with various difference of heights are substantiated. This requires a separate approach to the choice of parameters of retaining walls, namely the dimensions of the piles and their mutual placement, as well as the choice of the angle of the bulk soil along the slope. The calculations were performed using numerical simulation of the stress-strain state of the system "slope soils-retaining wall" using the finite element method. An elastic-plastic model of soil deformation with a change in soil parameters (deformation module) depending on the level of stresses in the soil is adopted. Hardening soil model (HSM) used. Calculations of slope stability involve taking into account the technological sequence of erection of retaining walls and modeling of the phased development of the pit. The simulation was performed in several stages: Stage 1 - determination of stresses from the own shaft, Stage 2 - assessment of slope stability before construction, Stage 3 - installation of retaining wall piles, Stage 4 - assessment of slope stability after landslides. Based on these studies, practical recommendations were developed for the design of each section of the retaining wall in accordance with the characteristic cross-sections.


2018 ◽  
Vol 14 (1) ◽  
pp. 47-54
Author(s):  
Pieter Kunu ◽  
Marcus Luhukay

Research has been conducted with the aim of mapping a potential landslide of soil that is alleged to be happening on a national road development area on the island of North Maluku Sanana island because in some locations excavations or cutting slope were conducted for build trails. Research was done by survey method, by analysis of land as well as the analysis of soil samples in the laboratory against some physical-chemical soil parameters to predict the potential for landslide of soil. The results showed that in the developed area of national roads, there were some points or locations with the potential landslide. However, by cutting slope of landslide the potential became greater, things which would be very threatening road users on the sections of the road that passes through the hilly and mountainous regions. The cutting slopes have been disturbing the equilibrium slope stability or lower slopes so the landslide is easy to happen. Mitigation efforts can be done by building a retaining structure at the foot of the slopes, the angle of the cutting slope made slightly sloping and in the upper part land use should be preserved and enriched with plant conservation to improve the stability of slopes. Keywords: a potential avalanche of soil, national road, slope stability   ABSTRAK Penelitian telah dilakukan dengan tujuan untuk memetakan potensi longsoran tanah yang diduga akan terjadi pada kawasan pengembangan jalan nasional di Pulau Sanana Maluku Utara karena di beberapa lokasi dilakukan penggalian atau pemotongan lereng untuk membangun jalur jalan. Penelitian dilakukan dengan metode survey dengan analisis lahan serta analisis sampel tanah di laboratorium terhadap beberapa parameter fisik-kimia tanah untuk memprediksi potensi longsoran tanah. Hasil penelitian menunjukkan bahwa pada kawasan ruas jalan nasional yang dikembangkan terdapat beberapa titik atau lokasi dengan potensi longsoran tergolong sedang. Namun dengan adanya pemotongan lereng maka potensi longsoran menjadi semakin besar, hal mana akan sangat mengancam pengguna jalan di ruas-ruas jalan yang melewati kawasan berbukit dan bergunung. Pemotongan lereng telah mengganggu keseimbangan lereng atau menurunkan stabilitas lereng sehingga longsoran mudah terjadi. Upaya mitigasi dapat dilakukan dengan membangun struktur penahan di kaki lereng, sudut pemotongan lereng dibuat landai dan penggunaan lahan di bagian atas lereng harus dipertahankan dan diperkayadengan tanaman konservasi untuk meningkatkan stabilitas lereng yang sudah terganggu. Kata kunci: jalan nasional, potensi longsoran tanah, stabilitas lereng


2021 ◽  
Vol 13 (7) ◽  
pp. 4046
Author(s):  
Vittoria Capobianco ◽  
Kate Robinson ◽  
Bjørn Kalsnes ◽  
Christina Ekeheien ◽  
Øyvind Høydal

Vegetation can be used as a nature-based solution (NBS) to restore rivers and mitigate water-triggered processes along streambanks. Roots are well known to improve the overall stability of slopes through hydro-mechanical reinforcement within the rooted zone. Vegetation-based solutions require the selection of species that are most suitable for specific locations, and they are aimed at restoring the natural state and function of river systems in support of biodiversity, flood management, and landscape development. Selecting a combination of different species along different zones of the riverbank can improve the conditions for the river system with regard to biodiversity and stability. Therefore, more studies are needed to investigate how the combination of a variety of different plant species can improve the stability of the riverbank. This paper presents a methodological approach for slope stability modeling including vegetation as well as the results obtained from a series of slope stability calculations adopting the proposed methodology. The analyses were carried out for critical shallow (≤3 m deep) shear planes of ideal benchmark slopes covered with four different plant combinations—(i) only grass, (ii) grass and shrubs, (iii) only trees, and (iv) trees, shrubs, and grass—for species typically found along streams in southeastern Norway. In this desk study, two types of tree species were selected, namely Norway spruce (Picea abies) and Downy birch (Betula pubescens). The Goat willow (Salix caprea) was selected as a shrub, while a common mixed-grass was chosen as grass. Vegetation features were obtained from the literature. The methodology was used for two main cases: (1) considering only the mechanical contribution of vegetation and (2) considering both the hydrological and mechanical reinforcement of vegetation. The main outcome of the numerical modeling showed that the purely mechanical contribution of vegetation to slope stability could not be decoupled from the hydrological reinforcement in order to have a realistic assessment of the roots improvement to the stability. The most critical shear surfaces occurred below the rooted zone in all cases, and the best performance was obtained using the combinations including trees. Considering the typical climate conditions in Norway, the hydro-mechanical reinforcement was most effective in the spring and for combinations including low height vegetation (i.e., grass and shrubs). The study concludes that a mixed combination of vegetation (trees, shrubs, and grass) is the most suitable for reaching the highest hydro-mechanical reinforcement of streambanks, together with erosion protection and boosting the ecosystem biodiversity. The current study can help practitioners determine which vegetation cover combination is appropriate for improving the current stability of a streambank with restoration practices.


2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Wenchen Fan ◽  
Ping Cao ◽  
Ke Zhang ◽  
Kaihui Li ◽  
Chong Chen

Chengmenshan copper mine, located at Jiujiang city in the Jiangxi Province, is a rarely lakeside open-pit mine in China. Since the open-pit is very close to Sai Lake, the seasonally changed water level and the distance between lake and slope have great influence to the stability of open-pit slope. Based on the drill data and geological sections, a numerical model of the slope is built. With the fluid-mechanical interaction associated, the stability of the slopes is numerically analyzed, in which different lake water levels and lake-slope distances are taken into consideration. The comparative analysis shows that a larger lake-slope distance can promise better slope stability and weaken the sensitivity of slope stability to water. The stability of slopes with different heights is analyzed to find that the stability weakens and the sensitivity is enhanced with the height increasing. To the most serious situation, the slope height and the lake water level being 238 m and 17.2 m, respectively, theFsvalue equals 1.18945 which is extremely closed to the allowable safety factor of 1.20 for slope design. According to the minimumFsfor slope design, the minimum distance between lake and open-pit slope is found to be 60 m.


Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 417 ◽  
Author(s):  
Abbate ◽  
Longoni ◽  
Ivanov ◽  
Papini

Landslides over steep slopes, floods along rivers plains and debris flows across valleys are hydrogeological phenomena typical for mountain regions. Such events are generally triggered by rainfall, which can have large variability in terms of both its intensity and volume. Furthermore, terrain predisposition and the presence of some disturbances, such as wildfires, can have an adverse effect on the potential risk. Modelling the complex interaction between these components is not a simple task and cannot always be carried out using instability thresholds that only take into account the characteristics of the rainfall events. In some particular cases, external factors can modify the existing delicate equilibrium on the basis of which stability thresholds are defined. In particular, events such as wildfires can cause the removal of vegetation coverage and the modification of the soil terrain properties. Therefore, wildfires can effectively reduce the infiltration capacity of the terrain and modify evapotranspiration. As a result, key factors for slope stability, such as the trend of the degree of saturation of the terrain, can be strongly modified. Thus, studying the role of wildfire effects on the terrain’s hydrological balance is fundamental to establish the critical conditions that can trigger potential slope failures (i.e., shallow landslides and possible subsequent debris flows). In this work, we investigate the consequences of wildfire on the stability of slopes through a hydrological model that takes into account the wildfire effects and compare the results to the current stability thresholds. Two case studies in the Ardenno (IT) and Ronco sopra Ascona (CH) municipalities were chosen for model testing. The aim of this paper is to propose a quantitative analysis of the two cases studies, taking into account the role of fire in the slope stability assessment. The results indicate how the post-fire circumstances strongly modify the ability of the terrain to absorb rainfall water. This effect results in a persistently drier terrain until a corner point is reached, after which the stability of the slope could be undermined by a rainfall event of negligible intensity.


2019 ◽  
Vol 9 (21) ◽  
pp. 4638 ◽  
Author(s):  
Moayedi ◽  
Bui ◽  
Kalantar ◽  
Foong

In this paper, the authors investigated the applicability of combining machine-learning-based models toward slope stability assessment. To do this, several well-known machine-learning-based methods, namely multiple linear regression (MLR), multi-layer perceptron (MLP), radial basis function regression (RBFR), improved support vector machine using sequential minimal optimization algorithm (SMO-SVM), lazy k-nearest neighbor (IBK), random forest (RF), and random tree (RT), were selected to evaluate the stability of a slope through estimating the factor of safety (FOS). In the following, a comparative classification was carried out based on the five stability categories. Based on the respective values of total scores (the summation of scores obtained for the training and testing stages) of 15, 35, 48, 15, 50, 60, and 57, acquired for MLR, MLP, RBFR, SMO-SVM, IBK, RF, and RT, respectively, it was concluded that RF outperformed other intelligent models. The results of statistical indexes also prove the excellent prediction from the optimized structure of the ANN and RF techniques.


2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Qibing Zhan ◽  
Xinjian Sun ◽  
Cheng Li ◽  
Yawei Zhao ◽  
Xinjie Zhou ◽  
...  

This study presents a stability analysis of a high-steep rock slope with two faults during excavations and evaluates the effectiveness of a proposed reinforcement method using prestressed anchor cables. A 3D finite difference model was established based on the strength reduction method using FLAC3D software. The influence of various fault conditions and the effectiveness of the reinforcement on the slope stability during the excavation process were analyzed and compared to field monitoring data. The numerical analysis and field monitoring results showed that the fault close to the slope surface (f20) was prone to the local instability under external forces caused by the excavation, but a fault further away from the slope surface (f14) had insignificant influence on the stability of the slope. Based on the numerical analysis results, the proposed reinforcement measure can increase the factor of safety (FOS) of the slope by 19.2%. The field monitoring data also showed that the displacement of the monitoring point gradually decreased after the reinforcement, and the deformation of the slope was effectively controlled.


1993 ◽  
Vol 30 (3) ◽  
pp. 391-408 ◽  
Author(s):  
R. Ulusay ◽  
M.F. Yolerì ◽  
V. Doyuran

Eskihisar open pit mine, located at Yatagan, southwest Turkey, produces thermal coal for a power generating plant. As mining of strips advanced southwards, instability appeared to be highly critical due to the movements in the southeast wall slopes adjacent to the state highway running parallel to the pit boundary. This situation called for an immediate response to initiate a detailed geotechnical investigation program and to redesign the pit slopes. This paper outlines the most probable mode and mechanism of instability along the southeast wall, as well as field and laboratory studies, results of back analysis, discussion of the data requirements, and results of slope stability analyses performed to ensure adequate overall stability. The studies revealed that the most critical failures may occur along two or three planar surfaces, by combination of fault, bedding plane, and localized strata steepening adjacent to the fault, in multiplanar failure mode controlled by faulted blocks. The stability is sensitive to changes in length of the lower part of the basal sliding surface, as well as to the configuration and shear strength of black and highly plastic underclay. The effects of a buttress of intact rock and slope flattening on the stability are compared and discussed. Key words : back analysis, multiplanar failure, shear strength, slope stability, toe buttressing.


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