Technical Info

The alignment of a new highway from Igoumenitsa to Evros in the North of Greece required several massive cuts in soil slopes. Mainly due to erosion and creep movements within the superficial layer of a cut soil slope, the shotcrete facing failed. The friction forces as a result of interaction between shotcrete facing and soil surface caused an overstressing of the stiff facing and finally its collapse. The shotcrete was removed and replaced by a flexible slope stabilization system consisting of a high-tensile steel wire mesh cover in combination with an adequate nailing.

One popular approach to achieving slope stabilization is covering the slope with flexible steel mesh facing. In North America these systems are typically anchored only at the top, allowing the mesh material to drape freely down the slope. The weight and friction of the mesh material provides stability, and allows controlled downward movement of material. More advanced installations provide deeper stabilization by holding the mesh to the surface with anchors or soil nails throughout.

One popular approach to achieving slope stabilization is covering the slope with flexible steel mesh facing. In North America these systems are typically anchored only at the top, allowing the mesh material to drape freely down the slope. The weight and friction of the mesh material provides stability, and allows controlled downward movement of material. More advanced installations provide deeper stabilization by holding the mesh to the surface with anchors or soil nails throughout.

The current state of the different methods of nailing soil bodies and their dimensioning is reported. Since 1984, construction technical authorities have been regulating the securing of building pit slopes with shotcrete and soil nails through notes of authorization from the German Institute for Construction Engineering (DIBt). The range of application of nailing is not, however, limited to the securing of building pit slopes. In the meantime, nailing has become the standard procedure for increasing the stability of historical retaining walls of natural stone.

Introduction
A landslide occurred on San Marcos Road located 1.9 miles north from Cathedral Oaks Road outside Santa Barbara, California. The landslide occurred during the peak rainfall in the 2004-05 rain season. San Marcos Road is a federal highway route that permits transportation northward from Santa Barbara.

Precursor to Failure
There were precursors to the landslide failure that were fortunately recognized prior to failure so that the road had been closed. Extensive fracturing was observed during a geologic review of the slope on the day preceding the landslide.

Mobility is a fundamental necessity of the 21st century living; although space is limited, sustainable development of the public transport sector and optimized line management have to be achieved; this, in regard to efficiency, costs and risks of natural hazards.

INITIAL SITUATION

At the beginning of this century, a reassessment of the natural hazard potential along the german highway B4 in the Harz mountain range called for protection measures.

HAZARD FROM SNOW SLIDES AND SNOW PRESSURE

Due to the increasing need for protection against rockfalls, flexible protection systems were developed in the last 15 years from energy absorption capacities of 150 kJ up to 5000 kJ. 1:1 field tests according to the Swiss guideline for the approval of rockfall protection kits are an important reason for these developments.

HAZARD TREE IMPACT

In steep, afforested terrain, being hit by a sliding tree is a frequently encountered hazard for people and infrastructure. The tree impact can result from either forest operations, old or instable trees or storms. If trees start sliding and lose their limbs, their trunks can reach relatively high velocities.

Chapman's Peak Drive (CPD) is a famous 10 km scenic road in South Africa that was closed to the public four years ago due to heavy rockfall and landslides. Extensive reconstruction works allowed the reopening in the beginning of 2004.

This paper presents the assessment of the rockfall hazards using innovative numerical and geotechnical methods. This includes a special GIS-based mapping of all potential rockfalls together with a corresponding 3D-trajectory analysis, an additional probabilistic analysis of the expected rockfalls and the design of the protective structures.