Slope stability (Soil & Rock)

Questa guida è indirizzata a tutti gli utenti del codice SSAP che desiderano avere una
panoramica completa delle possibilità di impiego offerte dal programma.
In particolare essa è rivolta ai professionisti e tecnici che possiedono già un certo grado di
conoscenza delle metodologie, e delle problematiche connesse, di verifica di stabilità dei pendii
costituiti da terreni sciolti e/o ammassi rocciosi fratturati, con o senza opere di rinforzo e
stabilizzazione.
La guida si propone di fornire un riferimento completo a tutti gli strumenti di lavoro e alle
procedure di calcolo implementate nel programma SSAP, sviluppate nel corso degli ultimi 26 anni
dall’Autore.
Una quantità di tempo considerevole è stata impiegata per la stesura di questa
documentazione, essendo essa parte integrante ed essenziale per garantire una buona qualità del
software.
Come per un qualunque programma di calcolo per scopi tecnico-scientifici, soggetto ad un
continuo processo di verifica e miglioramento, anche la documentazione interna ed esterna è
soggetta a revisioni ed ampliamenti. Costante cura dell'autore sarà informare gli utenti di tutte le
revisioni e migliorie apportate, affinché sia disponibile uno strumento di lavoro sempre al passo
con gli standard attuali.
La versione più aggiornata dei questa guida è scaricabile, in forma di un file .PDF, dal sito
ufficiale di SSAP: http://www.ssap.eu , che fornisce anche indicazioni sulla ultima versione
ufficiale del software e sulla Licenza d'uso Freeware (ovvero gratuita) per privati e Pubbliche
Amministrazioni, a partire dalla versione 4.0 (SSAP2010)..
Nel continuo processo di sviluppo di questo software sono di insostituibile aiuto i contributi
degli utilizzatori del programma attraverso suggerimenti e critiche costruttive, che nascono
dall'uso quotidiano e da applicazioni sopra casistiche reali. Al fine di garantire un trend continuo
nel miglioramento della qualità del software applicativo sviluppato, l'intervento degli utenti sarà
sempre assai gradito.
Si ringraziano pertanto tutti i numerosi utilizzatori che hanno fornito da più 25 anni, con i loro
suggerimenti e tests, la possibilità di migliorare in modo continuo la qualità d questo software.
Senza il loro contributo ciò non sarebbe stato possibile. Ringrazio quindi in modo particolare:

The Slope Stability Analysis Program (SSAP version 4.9.9 - 2019), is the first full freeware application for LEM implementing a series of characteristics usually available today only in commercial software. SSAP has been developed during 28 years (1991-2019). All computational procedures have been developed starting from published paper on LEM and from original developments by the author.
Current SSAP release (4.9.9 - 64 bit -2019) contains many new tools and original algorithms in order to obtain more reliable FOS values and using a more general approach to LEM with respect to the past.

SSAP2010 HIGHLIGHTS
Freeware software tool with large diffusion and use in Italy for professionals, students, researchers, and private and public companies.
28 years of development based on 100% original coding, testing, and continuous interaction with final users with the aims of software improvement.
Many original algorithms (e.g. sniff random search 2.7.1, and 2D map of local average FOS).
Numerical stability control and its reliability analysis; groundwater and fluid pressure management module; reinforcement structures etc.
interactions with various type of structures: as geogrids-geotextiles, MSEW,MSE, gabions, piles, walls, ground anchors.
Seismic pseudostatic methods.
5 Failure criteria Mohr-Coulomb, Tresca, Generalized Hoek-Brown (non-linear), Barton-Bandis(1990) (non-linear), Liquefaction: Olson -Stark.
Technical documentation on-line (still in Italian) and many real examples of application in natural and reinforced slopes.
Many applications in Italy, and some in México: case studies with high stratigraphic, geomechanics and hydraulic complexities.
Free download from the WEB: http://www.ssap.eu.
Full freeware user’s license for any type of applications.

To exactly implement the non-linear Hoek–Brown shear strength reduction in slope stability calculations, three aspects of the problem are considered. Firstly, the normal and shear stress relationship of the generalized Hoek–Brown criterion (2002 edition) is derived by introducing the Mohr–Coulomb instantaneous friction angle as a variable. Secondly, the instantaneous Mohr–Coulomb friction angle and cohesive strength are derived for a micro-unit at a given stress state and they can be used to describe the shear strength of the rock mass under different stress states. Finally, the implementation of the non-linear shear strength reduction is described and a slope example is selected to verify our method. This technique can be also applied to other non-linear failure criteria.

On the 9 th October 1963 a catastrophic landslide suddenly occurred on the southern slope of the Vajont dam reservoir. A mass of approximately 270 million m 3 collapsed into the reservoir generating a wave which overtopped the dam and hit the town of Longarone and other villages: almost 2000 people lost their lives. Many studies and researches were carried out on the geological and geomechanical aspects and several attempts were made to explain the kinematics and dynamics of the landslide. This large mass of studies and researches has greatly increased the understanding of such phenomena, recognizing their precursory activity, predicting their dynamic behaviour and identifying likely areas of triggering and deposition. This paper reports briefly all the information reported in related papers, referring to the geological studies, to the chronology of events before 9 th October 1963 and to the different interpretations of the landslide triggering and actual mechanics and dynamics.

Remote monitoring of slope movement using electronic instrumentation can be an effective approach for many unstable or potentially unstable slopes. Water levels can be observed using vibrating wire piezometers. Movements and deformation can be determined with electrolytic bubble " in-place " inclinometers and tiltmeters, extensometers, and time domain reflectometry (TDR). All of these instruments can be attached to a programmed on-site datalogger. The datalogger can collect readings at selected intervals and trigger an alarm or initiate a telephone message or page if predetermined movement intervals are exceeded. These systems are self-contained using cellular telephone communications and batteries charged by solar panels. Case studies in Central and Northern California illustrate the use and flexibility of this technology in monitoring slope stability problems.

SSAP2010 is a complete freeware software for checking the stability of natural and artificial slopes or with reinforcing elements.  SSAP2010 provides users with a set of original tools able to perform in-depth stability checks using only rigorous and innovative methods based on the advanced Limit equilibrium method and innovative search engines able to find the critical surfaces associated to minimum Safety Factor (Fs). The Slope Stability Analysis Program (SSAP version 5.0 - 2020), is the first complete, and freeware,  application of LEM (Limit Equilibrium Method) numerical methods  implementing a series of characteristics and functions, not only  available today  in commercial software but with the addition of innovative algorithms and original methods..
SSAP has been developed during 29 years (1991-2020). All computational procedures have been developed starting from published papers on slope stability computational techniques in geotechnical literature in the last 60 years, and from original developments by the author.
Current SSAP release (5.0 - 2020) contains many new tools and original algorithms in order to obtain more reliable Fs values and using a more general approach to LEM  (Advanced LEM) with respect  the past.  An Important integration is given with the adoption of original and innovative numerical methods and of a hybrid methodology between LEM and finite element method (FEM), here called qFEM.
A Windows WIN 10 graphic interface and a series of software tools for  the slope model assembly,  graphic visualization and reporting, complete the software. https://www.ssap.eu.

Main SSAP2010 HIGHLIGHTS
Freeware software tool with large diffusion and use in Italy for professionals, students, researchers, and private and public companies.
29 years of development based on 100% original coding, testing, and continuous interaction with final users with the aims of software improvement.
Many original algorithms (e.g. sniff random search 3.0, and 2D map of local average Fs by the new hybrid LEM -FEM method).
Numerical stability control and its reliability analysis; groundwater and fluid pressure management module; reinforcement structures etc.
interactions with various type of structures: as geogrids-geotextiles, MSEW,MSE, gabions, piles, walls, ground anchors, anchored steel wire mesh.
Dynamic analysis by Seismic pseudo-static methods and displacemement method.
5 Failure criteria Mohr-Coulomb, Tresca, Generalized Hoek-Brown (non-linear), Barton-Bandis(1990) (non-linear), Liquefaction: Olson -Stark (2003)
Technical documentation on-line (still in Italian) and many real examples of application in natural and reinforced slopes.
Many applications in Italy, and some in México: case studies with high stratigraphic, geomechanics and hydraulic complexities.
Free download from the WEB: https://www.ssap.eu.
User’s license Full freeware for any type of final applications (profit and no-profit).

ABSTRACT Homeowners who live near or on steep slopes of the Traverse Mountains along the Wasatch front in southern Salt Lake City, Utah (USA) are at risk where development of “master-planned communities” has been permitted on known landslide deposits since 2001. Some of the largest landslides in the state of Utah are being modified as road construction and residential development progresses. This paper reviewed the setting of the landslide-prone areas and used Geographic Information Systems (GIS) spatial tools to assess the value of local developments built on mapped slide features. Dataset overlays
were compiled to determine the vulnerability of residences, and to quantify potential monetary loss from a future landslide event. The key elements at risk include property, as well as the population, economic activities, and public services of a given region. An initial conservative figure calculated for the vulnerability of residents owning property exceeds $500 million for the Traverse Mountains region of Draper City, based on 2007 property values recorded at the Salt Lake County Assessors Office. In developing this area, the failure to consider existing and potential hazards has caused a myriad of tensions among local government officials, planners, financiers, state regulators, consultants, developers, realtors, and homeowners.

SSAP2010 is a complete freeware software for checking the stability of natural and artificial slopes or with reinforcing elements.  SSAP2010 provides users with a set of original tools able to perform in-depth stability checks using only rigorous and innovative methods based on the advanced Limit equilibrium method and innovative search engines able to find the critical surfaces associated to minimum Safety Factor (Fs). The Slope Stability Analysis Program (SSAP version 5.0 - 2020), is the first complete, and freeware,  application of LEM (Limit Equilibrium Method) numerical methods  implementing a series of characteristics and functions, not only  available today  in commercial software but with the addition of innovative algorithms and original methods..
SSAP has been developed during 29 years (1991-2020). All computational procedures have been developed starting from published papers on slope stability computational techniques in geotechnical literature in the last 60 years, and from original developments by the author.
Current SSAP release (5.0 - 2020) contains many new tools and original algorithms in order to obtain more reliable Fs values and using a more general approach to LEM  (Advanced LEM) with respect  the past.  An Important integration is given with the adoption of original and innovative numerical methods and of a hybrid methodology between LEM and finite element method (FEM), here called qFEM.
A Windows WIN 10 graphic interface and a series of software tools for  the slope model assembly,  graphic visualization and reporting, complete the software. https://www.ssap.eu.

Main SSAP2010 HIGHLIGHTS
Freeware software tool with large diffusion and use in Italy for professionals, students, researchers, and private and public companies.
29 years of development based on 100% original coding, testing, and continuous interaction with final users with the aims of software improvement.
Many original algorithms (e.g. sniff random search 3.0, and 2D map of local average Fs by the new hybrid LEM -FEM method).
Numerical stability control and its reliability analysis; groundwater and fluid pressure management module; reinforcement structures etc.
interactions with various type of structures: as geogrids-geotextiles, MSEW,MSE, gabions, piles, walls, ground anchors, anchored steel wire mesh.
Dynamic analysis by Seismic pseudo-static methods and displacemement method.
5 Failure criteria Mohr-Coulomb, Tresca, Generalized Hoek-Brown (non-linear), Barton-Bandis(1990) (non-linear), Liquefaction: Olson -Stark (2003)
Technical documentation on-line (still in Italian) and many real examples of application in natural and reinforced slopes.
Many applications in Italy, and some in México: case studies with high stratigraphic, geomechanics and hydraulic complexities.
Free download from the WEB: https://www.ssap.eu.
User’s license Full freeware for any type of final applications (profit and no-profit).

A 1225 m long, 35 m high zone earth filled embankment was being constructed from 1981 to 1984 from a British Regional Water Authority to regulate flows in the River Derwent in England. The Carsington Dam was planned to be one of the largest earth filled dams in Britain. Its reservoir capacity was 35 million m 3 and the watertight element was Rolled

Use of numerical modelling for back analysis of slope failure can provide a valuable insight into the underlying failure mechanisms and improve our understanding of factors controlling instability and geomorphology of slopes. This paper provides a brief overview of the range of methods that are available for slope instability analyses, and their respective benefits, using the back analysis of the Joss Bay Chalk cliff failure as a case example. A variety of analytical and numerical approaches are used to back analyse the failure to assess the potential impact of both the rock mass strength and discontinuity-controlled behaviour on the potential failure mechanism. Limit equilibrium analysis approaches are used to assess the sensitivity of the simulated model to variation in input parameters. Numerical simulation, constrained by the limit equilibrium models, is then used to evaluate the progressive nature of failure mechanism and directly simulate the trigger mechanism. Importantly, the modelling demonstrates that shear strain initiates at the base of the cliff and subsequently extends upwards resulting in tensile failure in the upper part of the slope. The case example demonstrates the capability of numerical models to simulate the progressive nature of slope failure, and their ability to evaluate the detrimental effects of a wave-cut notch at the base of a cliff.

APLIKASI GEOCOMPOSITE SEBAGAI DINDING PENAHAN TANAH PADA LERENG JALAN LABUAN-MALIGANO DI PULAU BUTON Darwis Panguriseng (Dosen Teknik Sipil Unismuh Makassar) 1. Konsep Perkuatan Tanah Perkuatan tanah merupakan salah satu metode atau teknik konstruksi yang tertua diterapkan oleh umat manusia. Tembok China (Great Wall of China) yang dibangun selama kurang lebih 500 tahun (722 SM-221 SM), ketika segmen yang melalui lahan rawa (low land) pondasi dinding diperkuat dengan ranting-ranting pohon konifer yang dicampur dengan rerumputan tertentu (Darwis, 2001). Demikian pula ketika bangsa Romawi membangun Via publica (jalan raya) yang pertama yaitu Via Appia (Jalan Appia), yang menghubungkan kota Roma dengan Brundusium (Brindisi) sebuah kota pelabuhan yang menjadi gerbang di wilayah timur Roma. Beberapa ruas jalan ini yang melalui kawasan low land menggunakan ranting-ranting cemara sebagai perkuatan lapisan tanah dasar jalan (subgrade). Penamaan Jalan Appia diambil dari Appius Claudius Caecus, yaitu nama pejabat Romawi yang memulai pembangunan jalan tersebut pada sekitar tahun 312 SM. Penggunaan ranting kayu sebagai perkuatan konstruksi pada zaman dahulu hanya didasarkan pada intuisi para ahli bangunan kuno, dan belum menggunakan teori apalagi dalam bentuk formula-formula matematis, baik dalam mendimensi maupun dalam menganalisis keandalan perkuatan tersebut. Orang pertama yang memperkenalkan konsep analisis perkuatan tanah secara ilmiah adalah Henry Vidal pada tahun 1968, seorang ahli Teknik sipil berbangsa Prancis dalam sebuah teori yang disebut Teori Reinforcement Earth. Konsep dasar perkuatan tanah dari Henry Vidal adalah bahwa suatu material gabungan (composite) yang dibentuk dari perkuatan berbentuk lembaran yang diletakkan horizontal pada tanah berbutir. Interaksi yang terjadi antara tanah dengan perkuatan diperoleh melalui gesekan yang terjadi akibat beban gravitasi. Penemuan Henry Vidal ini didasari oleh pengalaman sederhana melihat dua orang anaknya yang bermain perang-perangan dengan saling lempar pasir di pinggir pantai. Lalu salah seorang anaknya membuat tumpukan pasir sebagai benteng perlindungan dirinya. Akan tetapi karena pasir pantai yang ada tidak bisa ditumpuk tinggi untuk melindungi seluruh tubuhnya, maka dia mengambil daun kayu disekitarnya yang dihampar di atas tumpukan pasir lalu ditambahkan lagi tumpukan pasir, sehingga ketinggian tanggulnya dapat bertambah. Cara ini dilakukan berulang sampai beberapa lapis, hingga tanggul pertahanan anak tersebut dapat melindungi seluruh tubuhnya dari lemparan pasir dari adiknya. Henry Vidal yang menyaksikan aksi permainan kedua anaknya sejenak terkesimak, lalu menyimpulkan bahwa eksistensi lembaran daun di antara lapisan pasir ternyata dapat memperkuat lapisan pasir tersebut, sehingga tumpukannya bisa dibuat anak tersebut yang lebih tinggi. Dari kesimpulan itulah Henri Vidal mulai memikirkan rumusan aksi composite antara lapisan tanah dengan material sisipan sebagai bahan perkuatan. Perumusan formula

In this study, it was aimed at evaluating the slope stability conditions in a residential area exposed to two landslides in the past by using two-and three-dimensional limit equilibrium analyses. Two separate, but interdependent, landslides were observed in the investigated area. In 1992 and 1994, two landslides occurred in the region after heavy precipitation and caused damages on the houses and infrastructures. An extensive field work was performed to obtain input parameters for the analyses. In addition, an unmanned aerial vehicle was flown to obtain a three-dimensional view of the landslide area for better understanding of the past failures. The landslides occurred in a flysch-type material representing complex geological characteristics. Hoek-Brown failure criterion and Geological Strength Index were chosen for the strength and visual definition of the geological unit. Since the landslide triggering factor was precipitation, the analyses were focused on the water conditions causing the failure. Sensitivity and back-analyses were performed to obtain the conditions of failure. It was revealed that a high pore pressure ratio was needed to trigger the landslides. However, the second landslide was failed with a lower pore water pressure and the current topography was determined to be on the edge of failure with a slight increase in the pore pressure ratio. In other words, the study area was still found to be prone to possible landslides in the future.

The present paper investigates the stability condition of excavated slopes along new 3 rd line on Barkhera-Budni track on Bhopal-Itarsi rail route of West-Central Railway. The entire length of track alignment falls in the Deccan Plateau characterized by steep Ghat area. The track section contains highly jointed sandstone, shale and limestone which are prone to different form of rock failures intensified by moderate to high weathering conditions of the existing rock mass. Natural calamities such as cloud burst was also reported at specific section in rainy season that enhances the erodibility of the slope materials onto the proposed track. The proposed railway track is going to be one of the busiest routes making it less approachable for slope corrections in future. Therefore, this necessitates a site-specific stabilization solution of vulnerable excavated slopes for long-term stability and safe transportation along the proposed route. Prior to stability analysis, field and laboratory investigation were conducted to assess the geotechnical properties of rock. The common problems identified during site investigation were large boulders adjacent to track, water seepage into the slopes, sudden movement of slope materials during rainy season and limited Right of Way (RoW) for the project. Based on the observed susceptibility conditions of slopes, stability analysis was performed through Limit Equilibrium Method (LEM) using Mohr-Coulomb strength criteria. The Factor of Safety (FoS) of 1.5 is considered for safe slope design in existing rock mass conditions. Based on the failure patterns, FoS and analyzed stabilization scenario, benching of the slope along with RCC super passage wall towards the hill side with drainage towards track has been recommended as a stabilization measure with a drainage at every bench for effective disposal of water for seepage treatment. Rock bolting with combination of Steel and Poly Fiber Reinforced Shotcrete (SPFRS) were suggested to obtain the desired FoS whereas shotcrete along with wire mesh has been used for highly vulnerable weathered sections.

Στην εργασία ουτή διερευνάται η ευστάθεια των πρανών της κοιλάδας Κarοκαλίοu-Αλμυρής(Ν. Κορινθίας). Εντοπίστηκανυπάρxovτα προβλήματααστοχιών κοι προτείνονται μέτρα πρόληψης ή αναχοίτησης φαινομένων κατολισθήσεωνκαι γε νικότερων οστοχιών (καθιζήσεις, ερπυσμοί, κ.λπ.). Η περιοχή γεωτεκτανικά εντάσσεται στην Πελαγανική ζώνΤ1 και καλύmεται οπό καρστικοποιημένοuςΤριαδιtωύς ασβεστολίθοuς και Νεογενείς και Τεταρτογενείς αποθέσεις οπό μόργες, οργίλους, ιλυόλιθοuς, ψαμμίτες, κώνους κορημότων, κ.λπ.

This study combines novel and previously published data to create a new method of estimating anisotropic rock-mass strength in three dimensions that considers both the orientation and the non-persistence of multiple joint sets. Equations are developed to evaluate joint persistence as a function of joint set spacing-to-length ratio, strength reduction as a function of joint persistence, and strength reduction as a function of dip and dip direction difference between a joint set and the shear plane. Vector rotations are used to calculate the dip and dip direction difference between the orientations of joint sets and the assumed shear plane orientation, allowing anisotropic rock-mass shear strength to be estimated for any three-dimensional direction of shear. The result is reduced strength for shear in the directions parallel to jointing and increased strength for shear in directions non-parallel to jointing, with a continuous function of strength in between the two extremes. Input parameters for the system are rock discontinuity set statistics, intact rock strength, discontinuity strength, and RQD. A slope instability case history example is back analyzed using the strength estimation procedure. A calculation sheet that implements the methodology is presented and shared for digital download.

In-situ soil slopes are often reinforced with nails to improve their static and seismic performance. To evaluate the stability of slope, usually two-dimensional analysis on limit equilibrium methods (LEMs) are implement in the field of geotechnical engineering. The aim of this paper is to evaluate the response of the reinforced slope against seismic load by using LEM. In this study, GEO5 software was used by applying the seismic effect on the slope with reinforcement to improve the stability considering steel bars as reinforcement. The parametric modeling was done to determine the effect of seismic load with and without the inclination of reinforcing bar on the factor of safety. From the analysis, it is noted that soil reinforcement has significant effect on the improvement of the stability of slope and can be of an excellent option for the stability of slope in roadways and mountainous areas. Factor of safety gradually decreases with the increase in the value of horizontal seismic coefficient regardless of the methods used in the analysis. Morgenstern-Price method gives the elevated values of the factor of safety of slope whereas Petterson method gives the lowest factor of safety when slope with and without reinforcement is considered.

SSAP2010 is a complete freeware software for checking the stability of natural and artificial slopes or with reinforcing elements.  SSAP2010 provides users with a set of original tools able to perform in-depth stability checks using only rigorous and innovative methods based on the advanced Limit equilibrium method and innovative search engines able to find the critical surfaces associated to minimum Safety Factor (Fs). The Slope Stability Analysis Program (SSAP version 5.1 - 2022), is the first complete, and freeware,  application of LEM (Limit Equilibrium Method) numerical methods  implementing a series of characteristics and functions, not only  available today  in commercial software but with the addition of innovative algorithms and original methods..
SSAP has been developed during 31 years (1991-2022). All computational procedures have been developed starting from published papers on slope stability computational techniques in geotechnical literature in the last 60 years, and from original developments by the author.
Current SSAP release (5.1 - 2022) contains many new tools and original algorithms in order to obtain more reliable Fs values and using a more general approach to LEM  (Advanced LEM) with respect  the past.  An Important integration is given with the adoption of original and innovative numerical methods and of a hybrid methodology between LEM and finite element method (FEM), here called qFEM.
A Windows WIN 10 graphic interface and a series of software tools for  the slope model assembly,  graphic visualization and reporting, complete the software. https://www.ssap.eu.

Main SSAP2010 HIGHLIGHTS
Freeware software tool with large diffusion and use in Italy for professionals, students, researchers, and private and public companies.
29 years of development based on 100% original coding, testing, and continuous interaction with final users with the aims of software improvement.
Many original algorithms (e.g. sniff random search 3.1, and 2D map of local average Fs by the new hybrid LEM -FEM method).
Numerical stability control and its reliability analysis; groundwater and fluid pressure management module; reinforcement structures etc.
interactions with various type of structures: as geogrids-geotextiles, MSEW,MSE, gabions, piles, walls, ground anchors, anchored steel wire mesh.
Dynamic analysis by Seismic pseudo-static methods and displacement method.
5 Failure criteria Mohr-Coulomb, Tresca, Generalized Hoek-Brown (non-linear), Barton-Bandis(1990) (non-linear), Liquefaction: Olson -Stark (2003)
Technical documentation on-line (still in Italian) and many real examples of application in natural and reinforced slopes.
Many applications in Italy, and some in México: case studies with high stratigraphic, geomechanics and hydraulic complexities.
Free download from the WEB: https://www.ssap.eu.
User’s license Full freeware for any type of final applications (profit and no-profit). more details on SSAP technical Manual