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HYDRA-G Case Study

Building Monitoring

during TBM Excavations

The main line subway of an

European city is going to be

extended along the south

direction.

In order to create the new tunnel,

a TBM was used for drilling

activities.

The HYDRA-G radar installation

was carried out to monitor civil

structure and building

movements next to the new

metro line site, and during the

TBM transition period.

The HYDRA-G position is

highlighted by the yellow circle in

the image.

N

W E

S

AREA FRAMING

HYDRA-G Case StudyScope of the Project

HYDRA-G

Position

HYDRA-G

Line of Sight - LOS

HYDRA-G Case StudyArea Framing – HYDRA-G Positioning

The HYDRA-G radar system was placed in a stable area,

on a cement block of 1 m3.

The blue square in the image below indicates the

buildings that were selected for the monitoring

activities.

HYDRA-G Case StudyHYDRA-G Installation on September 22, 2017

HYDRA-G Case StudyFirst Step of the Campaign: 3D Point Cloud Creation with the SurfScan Software

Radar Pixel Creation: 22/09/2017

Installation and

beginning of the

monitoring

Selected radar pixels for real time

displacement visualization Creation of Time Series for Real time

Displacement: 22/09/2017

HYDRA-G Case StudySecond Step of the Campaign: Radar Monitoring Session

Phase 1

Wed 27 h 10:00 - Wed 27

h 18:00: TBM is

approaching the area.

Phase 3

Thursday 28 h 8:00 – Friday 29 h 15:00:

TBM drilling under the selected area. Main movements

(up to 5 mm) are shown here.

Phase 2

Wed 27 h 18:00 – Thu 28 h

08:00: Stop drilling for

technical reasons.

Building A

Phase 4

Friday 29 h 15:00 -

Saturday 30 h 09:00:

Stabilization of the selected

radar pixels. TBM finished

drilling between Friday and

Saturday night.

Building B

Building C

Building A

Building B

Building C

Phase 1LOS

displacement

up to 2 mm

Phase 2No displacement

due to TBM stop

Phase 4:Movement

stabilization

Phase 3 LOS displacement up to 6 mm

Monitoring – Time Series

Building A

Building B

Building C

Building ABuilding B Building C

The HYDRA-G radar system was able to

monitor in real time building and civil

structure movements above the subway

tunnel construction.

A detailed analysis of the data highlighted

the different movements between the

surveyed buildings.

Building A: an average of - 6 mm

displacement respect lo LOS

Building B: an average of ± 2 mm respect to

LOS

Building C: an average of +2 mm respect to

LOS

HYDRA-G Case StudyConclusion