UNITRACC - Underground Infrastructure Training and Competence Center

The structural calculations for starting, intermediate and target shafts include:

The dimensioning of the individual lining elements
Earth structural verification

(Image: Attention!)

The following must be taken into account in the load assumptions:

Earth and water pressure
Traffic loads
Introduction of the jacking force into the lining of the starting shaft and the tension forces in the lining of the target shaft

Sep 15, 2008

Desing load

(Image: Model of an earth pressure course as a consequence of the in-situ soil)

Earth pressure

soil-mechanical characteristic values of the geotechnical report or starting values of DIN 1055

(Image: Model of a water pressure course as a consequence of the in-situ groundwater)

Water pressure

height of the groundwater level

(Image: Model of an earth pressure course as a consequence of soil piles (traffic load))

Traffic load

actual loads from …

Sep 15, 2008

Dimensioning of the lining elements

(Image: Attention!)

When dimensioning the individual lining elements, account must be taken of the final condition as well as all construction phases of their installation and possible removal [Weiße75b].

Sep 15, 2008

Earth structural verification

The earth structural stability analysis includes:

Assessment against hydraulic ground failure during construction of the shaft before the introduction of the base for cut off groundwater
Assessment of buoyancy security after the introduction of base for cut off groundwater
Assessment of the earth bearing for introducing the jacking force into the subsoil behind the installed abutment.

The first two assessments that only apply to the shafts reaching …

Sep 15, 2008

Design of the abutment - verification of the earth bearing

The assessment of the earth bearing behind the abutment is taken as being satisfied when the activated earth resistance is greater than the soil stress that can be introduced as a result of the application of the jacking force (in combination with the lining wall) onto the subsoil.

(Image: Introduction of the jacking force into the subsoil)

Sep 15, 2008

Design of the abutment - examples of lined shafts

(Image: Principle sketch of a jacking station for microtunnelling with auger spoil removal installed inside the starting shaft) (Image: Examples of abutment designs - Abutment in the form of a reinforced concrete plate and an in cast concrete block during pipe jacking [TUGraz01])

Sep 15, 2008

Design of the abutment - examples of unlined shafts

(Image: Abutment design without shaft - Sketch [PJA83]) (Image: Abutment design without shaft - Of rammed sheet piles with filling and load distribution plate in front [FI-Zübli])

(Image: Abutment design without shaft - Plan view with backfilled intermediate spaces [FI-Zübli]) (Image: Abutment design without shaft - Front view [FI-Zübli])

Sep 11, 2008

Structural calculation

May 19, 2011

Utility Tunnelling - Starting and target shafts

This presentation is part of the series of presentations "Utility Tunnelling" and deals with the building of starting and target shafts and the design of exit and entry openings.

Jan 01, 1900

Content

The basis for the successful installation of supply and discharge lines using trenchless technologies requires detailed knowledge of the subsoil condition.

This presentation aims to provide an insight into the geological, hydrogeological, and geotechnical fundamentals. Additionally, it explains the various geotechnical investigation methods used to explore the subsoil.

Sep 22, 2008

Introduction

Fields of Geotechnical Engineering

The excavation of utility trenches and tunnels, as well as their safe construction, belong to the field of geotechnology.

In geotechnology, the soil (or rock) forms the subsoil and serves as construction material. It can also act as a load or serve as the load-bearing and stabilizing material.

In other words, geotechnology focuses on the requirements needed to use soil (or rock) in the form of stable and functional civil engineering structures [Schmi96].

Feb 10, 2020

Introduction

Geotechnology

Fields of Geotechnology
The field of Geotechnology includes, among others, the following scientific disciplines:

Geological Engineering:
A science that involves the application and evaluation of geological knowledge and consolidated findings when dealing with construction works.

Soil and Rock Mechanics (Geomechanics):
A science with the objectives to:
- Investigate the subsoil
- Describe and classify the soil
- Determine the strength and deformation …

Sep 22, 2008

Introduction

Feb 10, 2020

Due to its varying behavior when loaded by structures, [EN1997-1:2009] classifies the subsoil into:

Undisturbed and disturbed soil (collectively referred to as soil)
Rock (solid rock)

In contrast, [ASTM D2487] only distinguishes between the various types of soil, including:

Gravels
Sands
Silts
Clays
Organic soils

In practice, however, a distinction between undisturbed and disturbed soil is not made. Consequently, all loose material is covered …

Feb 10, 2020

Classification of Soil and Rock Materials

Soil:
An assemblage of mineral particles and/or organic matter in the form of a deposit, but sometimes of organic origin. Soil can be separated by gentle mechanical means and includes variable amounts of water and air (and sometimes other gases).

Note 1:
The term soil is also applied to piled ground made of replaced natural soil or man-made materials that behave similarly to soil, such as crushed rock, blast furnace slag, and fly-ash.

Note 2:
Soils …

Feb 10, 2020

Definition subsoil

Subsoil:
A layer of soil or rock that serves as a foundation or bedding for structures (such as lines or shafts), or one that is otherwise affected by construction work [DIN4020:2010].

Feb 10, 2020

Definitions geology, engineering geology and hydrogeology

Geology:
The science that studies the structure, composition, and development of the Earth, especially the Earth's crust, and the creatures that have inhabited it throughout the history of the Earth [Meyer08].

Hydrogeology:
A branch of applied geology that deals with the investigation of groundwater bedding and deposits, as well as the groundwater balance. It analyzes the relationship of water to rock, its bedding, and the changes in properties

Feb 10, 2020

Geotechnical boundary counditions

(Image: Attention!)

In trenchless installation, as in all underground construction, the limiting geotechnical conditions are crucial in selecting a suitable drilling or jacking technique.

Therefore, before starting the work, it is necessary for the planning and executing engineer to acquire sufficient knowledge of the respective subsoil. Only in this way can a successful and economical execution of the project be ensured.

Feb 10, 2020

Subsoil behaviour

The subsoil investigation should aim to determine the relevant subsoil properties for the application being considered and the required subsoil characteristics.

Therefore, especially for the choice of a suitable construction method, excavation tools, and conveying system, the behavior of the subsoil must be analyzed in order to determine:

Stability of the borehole, the opened cavity, or the working face
Ease of fragmentation (for rock) or ease of

Feb 10, 2020

Definition subsoil risk

Subsoil risk:

A natural, unavoidable remaining risk that, when considering the subsoil and the ingredients present in the subsoil (such as groundwater, contamination, etc.), can lead to unpredictable effects and obstacles. This can occur even if the party providing the subsoil has fulfilled their duties in the complete investigation and description of the subsoil and groundwater conditions, and even if the construction party has also fulfilled their …

Feb 18, 2020

Rock formations and structures of the earth crust

(Image: Schematic profile of the connections between the formation of rock material and the structures of the earth's crust [Wagen79])

Feb 10, 2020

Subsoil - Geomechanical Principles

Sep 22, 2008

Hydrogeological fundamentals

Hydrogeology

(Image: Presentation of the portable water/ salt water boundary in coast areas)

Subsoil investigation includes the acquisition of the respective primary hydrogeological conditions in the form of:

Groundwater level and variation,
Flow velocity and direction,
Permeability,
Incoming water quantity,
Hydrostatic pressure condition,
Chemistry of the water.

Sep 22, 2008

Hydrogeological fundamentals

Definition groundwater

Groundwater¹⁾:
Underground water that consistently fills cavities²⁾ in the lithosphere and whose movement is controlled by gravity exclusively (with reference to [DIN4049-3]).
Remark:
¹⁾ In compound terms always provided that misunderstandings are excluded the components groundwater can be replaced by the abbreviation gw (without blank).
²⁾ Here, cavities stand for a collective term for pores, fissures (separating joints) and karst cavities within …

Sep 22, 2008