A case study of the pore water pressure fluctuation on the slip surface using horizontal borehole works on drainage well

Tsao, Tsung-Ming; Wang, M.K.; Chen, M.C.; Takeuchi, Yoshitugu; Matsuura, Sumio; Ochiai, H

doi:10.1016/j.enggeo.2004.11.002

Cited by 26 publications

(14 citation statements)

References 20 publications

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“…The water induces movements for two main reasons: (i) infiltration increases water pore pressure on the slip surface and remarkably decreasing shear strengths of the landslide mass (Tsao et al, 2005); (ii) water creates an increase of weight on the slope and destabilizes the mass by loading (Brunsden, 1999). However, during the movement, the slip surface evolution creates a new distribution of fluid pressure that can modify the movement (Cornet et al, 2003) linked with a hydromechanical effect.…”

Section: Introductionmentioning

confidence: 96%

Experimental analysis of groundwater flow through a landslide slip surface using natural and artificial water chemical tracers

Binet

Jomard

Lebourg

et al. 2007

Hydrological Processes

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Abstract:Artificial and natural tracer tests combined with high accurate electronic distancemeter measurements are conducted on a small landslide with a well known slip surface geometry. Outflow yields and chemical contents are monitored for all the experiment duration and they analyzed to estimate the slip surface hydraulic parameters. The main result is that the slip surface acts as a drain for groundwater flows that evacuates interstitial pressures in the slope and brings the sliding mass to be more stable one.

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Section: Introductionmentioning

confidence: 96%

Experimental analysis of groundwater flow through a landslide slip surface using natural and artificial water chemical tracers

Binet

Jomard

Lebourg

et al. 2007

Hydrological Processes

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“…In the period between 1994 and 1998, the landslide enlarged, partially retrogressively into the hinterland, 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 (Vlaj andŽigman, 2001). Consequently, the landslide destroyed the state road (called Panoramska cesta) Solčava (642 m) -Sleme (1308 m) at the altitude of ca 1110 m, and a new pontoon steel bridge had to be built instead.…”

Section: The Evolution Of the Macesnik Landslidementioning

confidence: 99%

“…This important aspect should not be overlooked in order to ensure the longevity of the mitigation works. Nevertheless, drainage wells have been widely used as a landslide control work, quite often in combination with horizontal drain borings in order to drain groundwater even more effectively (Nakamura, 1988;Wichter et al, 1988;Beer et al, 1992;Peila et al, 1992;Tsao et al, 2005;Shou and Chen, 2005).…”

Section: Introductionmentioning

confidence: 99%

Stepwise mitigation of the Macesnik landslide, N Slovenia

Mikoš

Fazarinc

Pulko

et al. 2005

Nat. Hazards Earth Syst. Sci.

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Abstract. The paper gives an overview of the history of evolution and mitigation of the Macesnik landslide in N Slovenia. It was triggered in 1989 above the Solčava village, but it enlarged with time. In 2005, the landslide has been threatening a few residential and farm houses, as well as the panoramic road, and it is only 1000 m away from the Savinja River and the village of Solčava. It is 2500 m long and up to more than 100 m wide with an estimated volume in excess of 2 million m 3 . Its depth is not constant: on average it is 10 to 15 m deep, but in the area of the toe, which is retained by a rock outcrop, it reaches the depth of 30 m. The unstable mass consists of water-saturated highly-weathered carboniferous formations. The presently active landslide lies within the fossil landslide which is up to 350 m wide and 50 m deep with the total volume estimated at 8 to 10 million m 3 . Since 2000, the landslide has been investigated by 36 boreholes, and 28 of them were equipped with inclinometer casings, which also serve as piezometers. Surface movements have been monitored geodetically in 20 cross sections. This helped to understand the causes and mechanics of the landslide. Therefore, landslide mitigation works were planned rather to reduce the landslide movement so that the resulting damages could be minimized. The construction of mitigation works was made difficult in the 1990s due to intensive landslide movements that could reach up to 50 cm/day with an average of 25 cm/day. Since 2001, surface drainage works in the form of open surface drains have mainly been completed around the circumference of the landslide as the first phase of the mitigation works and they are regularly maintained. As a final mitigation solution, plans have been made to build a combination of subsurface drainage works in the form of deep drains with retaining works in the form of concrete vertical shafts functioning as deep water wells to drain the landslide, and as dowels to stop the landslide movement starting from the slide plane towards its surface. Due to the length of the landslide and its longitudinal geometry it will be divided In Slovenia, this sort of support construction, known from road construction, was used for the first time for landslide mitigation. The monitoring results show that the landslide displacements have been drastically reduced to less than 1 cm/day. As a part of the stepwise mitigation of the Macesnik landslide, further reinforced concrete shafts are to be constructed in the middle section of the landslide to support the road crossing the landslide. At the landslide toe, a support construction is planned to prevent further landslide advancement, and its type is still to be defined during the procedure of adopting a detailed plan of national importance for the Macesnik landslide.

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“…Compressive effective normal stresses (σ n '-P f ) press the opposing discontinuity walls together and resist sliding motion along the discontinuity surface, which can be induced by shear stresses (τ) acting parallel to the discontinuity plane. A reduction in the effective normal stress state leads to the normal opening of discontinuities, inducing a reduction of the internal shear strength of discontinuities or of the failure surface [37]. Deep in the slope and at the slope toe, where principal stresses are all compressive, an interstitial pressure increase can then induce slip on favourably oriented discontinuities.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale characterization of coupled hydromechanical behavior of a fractured-porous slope in response to free water-surface movement

Guglielmi¹,

Cappa

Rutqvist

et al. 2008

International Journal of Rock Mechanics and Mining Sciences

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To better understand the role of groundwater-level changes on rock-slope deformation and damage, a carbonate rock slope (30 m × 30 m × 15 m) was extensively instrumented for mesoscale hydraulic and mechanical measurements during water-level changes. The slope is naturally drained by a spring that can be artificially closed or opened by a water gate. In this study, a 2-hour slope-dewatering experiment was analyzed. Changes in fluid pressure and deformation were simultaneously monitored, both at discontinuities and in the intact rock, using short-base extensometers and pressure gauges as well as tiltmeters fixed at the slope surface. Field data were analyzed with different coupled hydromechanical (HM) codes (ROCMAS, FLAC 3D , and UDEC).Field data indicate that in the faults, a 40 kPa pressure fall occurs in 2 minutes and induces a 0.5 to 31 × 10 -6 m normal closure. Pressure fall is slower in the bedding-planes, lasting 120 minutes with no normal deformation. No pressure change or deformation is observed in the intact rock. The slope surface displays a complex tilt towards the interior of the slope, with magnitudes ranging from 0.6 to 15 × 10 -6 rad.Close agreement with model for both slope surface and internal measurements is obtained when a high variability in slope-element properties is introduced into the models, with normal stiffnesses of k n_faults = 10 -3 × k n_bedding-planes and permeabilities of k h_faults = 10 3 × k h_bedding-planes . A nonlinear correlation between hydraulic and mechanical discontinuity properties is proposed and related to discontinuity damage. A parametric study shows that 90% of slope deformation depends on HM effects in a few highly permeable and highly deformable discontinuities located in the basal, saturated part of the slope while the remaining 10% are related to elasto-plastic deformations in the low-permeability discontinuities induced by complex stress/strain transfers from the high-permeability zones. The periodicity and magnitude of free water-surface movements cause 10 to 20% variations in those local stress/strain accumulations related to the contrasting HM behavior for high and low-permeable elements of the slope. Finally, surface-tilt monitoring coupled with internal localized pressure/deformation measurements appears to be a promising method for characterizing the HM properties and behavior of a slope, and for detecting its progressive destabilization.

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A case study of the pore water pressure fluctuation on the slip surface using horizontal borehole works on drainage well

Cited by 26 publications

References 20 publications

Experimental analysis of groundwater flow through a landslide slip surface using natural and artificial water chemical tracers

Experimental analysis of groundwater flow through a landslide slip surface using natural and artificial water chemical tracers

Stepwise mitigation of the Macesnik landslide, N Slovenia

Mesoscale characterization of coupled hydromechanical behavior of a fractured-porous slope in response to free water-surface movement

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