Wellpoint dewatering design layout

Barton - Bandis Shear Strength Estimation

Barton - Bandis shear strength estimation criterion for rockmass discontinuities (upper and lower bound approach and rock shear test data).

Rock masses contain discontinuities such as bedding planes, joints, shear zones and faults. The shear resistance along discontinuities, which governed the shear resistance of the rock mass, depends on acting normal stresses, interface lentgh, interface roughness etc.  By measuring the shear strength of rock discontinuities of similar length, a significant variation occurs for the τ values, at low confinying stresses. The shear strentg criterion proposed by Barton make use of the following parameters to estimate the shear resistance and the shear strentgh parameters c (cohesion) and φ (angle of internal friction):

·         basic friction angle (Φ_b) determined as the strenth resistance on smooth planar surface

·         joint roughness coefficient (JRC)

·         joint compression strength (JCS)

·         probable filling material and its mechanical properties (such as clay gouge)

It should be also noted that the range of stength variation is reduced as the stresses are increased.

Hoek - Brown Failure Criterion

 

The criterion starts from the properties of intact rock and then introduced factors to reduce these properties on the basis of the characteristics of joints in a rock mass. The rock mass shear strength is estimated using the Hoek and Brown failure criterion (edition 2002), where rock mass is considered as homogeneous material and an average value is determind by fitting a linear Mohr - Coulomb relationship by least squares method.

In the above example a rockmass of conglomerate is considered, and taken into account the variation of data and parameters (upper and lower bound). 

 

Reverse fault

Massive rock slope failure (Cornwall cliff collapse)

http://www.bbc.co.uk/news/uk-15251292

Geologist Richard Hocking. who filmed a massive cliff fall in Cornwall, says it was the most exciting thing that he has ever seen.

Thousands of tonnes of rock fell into the sea at North Cliffs near Hayle two weeks ago - just days after part of the coastal footpath was diverted.

Mr Hocking, who is a soils and materials engineer for Cornwall Council, was there to assess the situation when the collapse happened. He had his camera with him and managed to capture the event on it.

7th class slope failure (after Cruden & Varnes '96)

Soil and Rock Slope Stability

Embankment slope stability analysis

 Road cut stability determination with proposed stability measures (rock bolts)

Plane and wedge failure analysis with EzSlide and the calculated FoS

Rock slope stability - wedge failure

Απεικόνιση αποτελεσμάτων κινηματικών αναλύσεων ως προς σφηνοειδή ολίσθηση (wedge) για κάθε εξεταζόμενο πρανές και για κλίσεις 2:1 και 3:2

Rock slope stability - block theory

 

Ανάλυση ορύγματος Ο10 κατά τη θεωρία των μπλοκ

Analysis according to block theory for O10 cut

Methane and water jet after 25m

Methane gaz and water jet after 25m borehole during geotechnical investigation work.
The area under investigation consisted of grey silty clay of high plasticity (CH - OH) with peat layers at various depth.
After 25m, a layer of more permeable silty sand (SM) give rise of gaz jet at the beginning, and after about 30min, silty sand together with water come out for at least 3 hours.

Geotechnical Cross Section - Road Cutting

Γεωτεχνική τομή ορύγματος με στοιχεία ερευνητικών γεωτρήσεων, γεωλογικής χαρτογράφησης και τεκτονικών καταγραφών
γεωλογικές, γεωτεχνικές, τεχνικογεωλογικές, εδαφοτεχνικές, έρευνες, μελέτες, γεωλογικά, τεχνικογεωλογικά, εδαφοτεχνικά, γεωτεχνικά έργα, ερευνητικές γεωτρήσεις, εργασίες, έρευνα εδάφους, υπεδάφους, γεωλογική, τεχνικογεωλογική, εδαφοτεχνική, γεωτεχνική έρευνα, μελέτη, γραφείο, εταιρία, γεωτεχνικών, τεχνικογεωλογικών, εδαφοτεχνικών, γεωλογικών ερευνών, μελετών, ανόρυξη, δειγματοληπτικών, ερευνητικών γεωτρήσεων, βραχομηχανική, μελέτες ευστάθειας βραχωδών και εδαφικών πρανών, καταγραφή ερευνητικών γεωτρήσεων, επιτόπου δοκιμές, εδαφοτεχνική μελέτη, εδαφοτεχνική έρευνα, παράμετροι διατμητικής αντοχής, αντοχή βράχου, βραχοσφήνες, block theory

Taiwan Freeway No. 3 landslide probe finds likely causes

Written by Randy Post (taken from http://geoprac.net/)

Wednesday, 13 April 2011 16:18

A panel of experts in civil engineering and geotechnical engineering has completed their investigation into the failure of the slope above Freeway No. 3 in Taiwan last April that killed 4 people. Their forensic geotechnical investigations concluded that the dip slope was already marginally stable. But they noted that they found corroded steel ground anchors that were part of the retaining system meant to restrain the slope. They conjecture that even though the contractor followed the relevant standards at the time of constructions, somehow voids formed around the cable during the grouting process and made the cable susceptible to corrosion. Also noteworthy is that as a result of this failure, Taiwan's National Freeway Bureau has changed standards for grouting ground anchors. They also conducted a comprehensive survey of all slopes along freeways and identified 32 slopes that were placed on a priority list for monitoring and inspection and 17 were found to need some form of mitigation. [Source: Taipei Times. Image: Sulekha.com]

Rock Slope Stability _ unstable rock treatment

from GeoPrac.net Monthly Newsletter #24 - 2011 April/May

http://geoprac.net/geonews-mainmenu-63/65-geologic-hazards/581-video-helicopter-based-rock-scaling-qsledgehammerq

There is a relatively new version of a video that came out in 2009 where the Norwegian Public Road Administration hired a helicopter to try to scale loose rock with a wrecking ball. This version has english subtitles explaining a few things, and also shows another technique they tried for scaling rock, water bombing!