Case studies on Deep-seated landslidesslope deformation (2).pptx

2 Case studies have been presented over deep seated
landslides and methods incorporated to mitigate them.

1. Case Study On Deep-Seated Landslides/Slope Deformation Ginyard International Co. Presented by Saqib Khursheed Wani Tunnel Engineering 2023PTE0073 1

2. https://en.wikipedia.org/wiki/Landslide#/media/File:Landslide_in_Cusco,_Peru_-_2018.jpg accessed on (21/11/23) Introduction to deep- seated Landslides. Deep-seated landslides are rooted in bedrock, are often slow moving, and can cover large areas and devastate infrastructure and housing developments. This depth can range from ten feet to several hundreds of feet. These slides tend to be a result of change in the geologic and hydrologic processes in the area of the landslide, such as seismic shaking or increased levels of groundwater. Deep-seated landslides usually occur as translational slides, rotational slides, or large block slides Shallow-rapid landslides are debris-flow slides that occur within the forest rooting zone, generally less than 10 feet deep. Typically initiated by intense rainfall and/or rapid snowmelt Shallow slides usually follow a long saturation period that is punctuated by an intense burst of precipitation over several hours or a few days. Based on speed and size/scale A landslide generally refers to the downhill movement of rock, soil, or debris 2

3. Macesnik landslide M. Mikoˇs et al.: Stepwise mitigation of the Macesnik landslide, N Slovenia 1000m away from the Savinja River and the village of Solcava in Norther n Slovenia near the border with Austria. Is more than 2,500 m long, up to 100 m wide, and, on average, 10 to 15 m deep with an estimated volume of the sliding mass about 2 million m 3 . The active landslide lies within the fossil landslide that is up to 350 m wide and 50 m deep with the total volume estimated at 8 to 10 million m 3 . The crown of the landslide is at an altitude of 1,360 m and the toe, where the landslide was stopped by a large rock outcrop, at 840 m asl T he Macesnik landslide was triggered by complex geological conditions at the junction of Carboniferous, Triassic, and Oligocene rocks in 1989 above the Solcava village, but it enlarged with time. In the period between 2000 and 2004, the landslide movements in the most critical upper part of the landslide reached up to 50 cm/day with an average value of 15 cm/day. In 2005, the landslide has been threatening a few residential and farm houses, as well as even some roads. Learn More uploaded by Mikoš Matjaž 3

4. Causes & development Firs t triggered in1989 due to large flooding in the Savinja River basin. Initially had no direct influence on the residential buildings, farm houses and the local infrastructure Thus till1994 no remediation activities were underway in the landslide area 01 Between 1994 and 1998, the landslide enlarged and it especially advanced on the slope. Surficial drainage of the landslide by earthen ditches and prefabricated concrete “canalettes”, carried out and maintained in this period, was unsuccessful and did not help to stabilise or at least slow down its advancement 02 Consequently, the landslide destroyed the state road (called Panoramska cesta) and in 1996, the landslide advanced again and destroyed a turn on the same state road .It a lso posed a threat to water supply system may times. 03 In 1999, its further advancement was stopped by a large rock outcrop. In 2005, the toe of the landslide has stayed at the altitude of 840m. As a precaution measure, a mechanical alarm system was established below the landslide toe and connected to the regional early warning and alarm center . uploaded by Mikoš Matjaž M. Mikoˇs et al.: Stepwise mitigation of the Macesnik landslide, N Slovenia 4 04

5. Data from the drilling cores show that the sliding mass was heterogeneous, mainly dark-grey stiff clay with layers of more permeable clayey gravels of different thicknesses a t different depths. Investigations and reports In 2001, after special law on large landslides being adopted, Macesnik was given fresh financial support. The time distribution of the surface displacements of the Macesnik landslide in the period 2000–2004 in selected cross sections were carried In several phases, all together 36 boreholes were drilled at and around the landslide. Investigation proved that the Macesnik land slide was triggered within a much larger fossil landslide out of which around one quarter of the volume had been activated Following rock types were determined;- Carboniferous rocks Triassic rocks Oligocene rocks Talus slope M. Mikoˇs et al.: Stepwise mitigation of the Macesnik landslide, N Slovenia uploaded by Mikoš Matjaž uploaded by Mikoš Matjaž 5

6. Planning and execution of the mitigation measures Lowering of ground water pressures by deep drainage trenches filled with gravels in the upper part of the landslide Planning of restraining structures in such a way that there is no sliding of mass away from the structure. Support structures should be formed by grouping several deep shafts made of reinforced concrete with supportive and drainage functions (as deep water wells). Planned mitigation of the Macesnik landslide will follow the division of the landslide into 3 areas: Upper part-around the pontoon bridge Middle part-around panoramic road Lower part-around and above the rock outcrop that temporarily stopped further landslide advancement M. Mikoˇs et al.: Stepwise mitigation of the Macesnik landslide, N Slovenia 6

7. Reinforced concrete shafts proved to be an effective way of remediating a landslide such as the Macesnik landslide after it was efficiently slowed down by a system of deep drainage trenches. The measurements of the quantity of ground water that gravitationally flows from the RC shafts have indicated an effective draining of the landslide mass with low permeability around the shafts and effective lowering of water pressures in the landslide mass. Following the first example, this technology was successfully used in another case, namely at the Slano blato landslide, W Slovenia In one year after their completion, geodetic measurements at the shafts’ top have shown no displacements. There were no horizontal displacements even of the inclinometers embedded in the secondary coating of the RC shafts. Conclusions Following the first example, this technology was successfully used in another case, namely at the Slano blato landslide, W Slovenia M. Mikoˇs et al.: Stepwise mitigation of the Macesnik landslide, N Slovenia 7

8. 8 References 1. Mikoš, M., Fazarinc, R., Pulko, B., Petkovšek, A., and Majes, B.: Stepwise mitigation of the Macesnik landslide, N Slovenia, Nat. Hazards Earth Syst. Sci., 5, 947–958, https://doi.org/10.5194/nhess-5-947-2005, 2005. 2. Logar J, Fifer BK, Kočevar M, Mikoš M, Ribičič M, Majes B (2005) History and present state of the Slano blato landslide. Nat Hazard Earth Syst Sci 5:447–457 3. Pulko, B., Majes, B., Mikoˇs, M., 2014. Reinforced concrete shafts for the structural mitigation of large deep-seated landslides: an experience from the Macesnik and the Slano blato landslides (Slovenia).

9. Thank you [email protected] IIT JAMMU 8 R. Fazarinc in 2004