ASE s.r.l. produces and commercializes innovative instrumentations designed for geotechnical and environmental monitoring. Our systems are fully automated and the data management involves the acquisition, storage and elaboration of data along with their representation through a web based platform.
The construction of underground excavations is characterized by a high degree of uncertainty, due to the implicit simplifications of the calculation models and the difficult determination of the geotechnical and geomechanical parameters of the tunnel surroundings. The design assumes a predictive role, based on the best hypotheses of soil/rock behaviour and needs to be validated or revised during the construction phase. For this reason, design forecasts and monitoring outcomes should be continuously compared during construction. The Cir Array is the ideal instrument to deal with this task, since it provides immediate information about the deformation of the excavation profile and it does not interfere with the following construction phases.
What is it?
Cir Array is an innovative tool designed for near-real time monitoring of convergence phenomena and localized deformations inside tunnels during both the excavation and operational phases. The instrument can be installed directly in contact with the rock mass or on the final concrete lining to evaluate the behaviour of the excavation profile and/or of the structural elements.
How is it made?
The Cir Array instrument is composed of a sequence of synthetic resin nodes (Tunnel Links) connected by a fiberglass rod. The rod is required to preserve the alignment and distance between the nodes.
The tool can be customized according to the specific needs, to the tunnel size and to the required resolution. Each node includes a 3D MEMS accelerometer that measures the Earth's gravitational field components and a thermometer required for the thermal compensation of MEMS.
The instrument is shipped in a box, divided into segments, in order to make it easy to carry inside the tunnel, even when its diameter is small. The weight of the instrument does not generally exceed 15 kg and can, therefore, be carried by hand.
Once assembled, the Cir Array can be installed against the rock mass or the final concrete lining through appropriate metal clamps. For more information, please take a look at the Cir Array installation manual.
When a displacement occurs, the node changes its position to follow the movement of the tunnel. After been read, every tilt sensor of the array records the different position (raw data) and sends the information to the control unit. This unit transmits the raw data to the elaboration centre, where a software processes them (ADC point) to return information about the real displacement of the node (physical units). The accelerometer gives information about the rotation of the node, referring to the constant gravity acceleration g. Like every sensor based on gravity measure, MUMS cannot identify rigid translations. The on-board thermometer is necessary to correct the thermal effects on the accelerometer, using the calibration values. This sensor also provides the temperature along the length of the array.
MEMS sensors is located at the centre of each Link and measures the three components of the gravitational field in its reference system, starting from an initial configuration (zero reading). When a movement arises, the variation of the different components of gravity gives back the information of the displacement. In this way, it is possible to calculate the underground rotation and the local displacement of each Link and finally build a curve of cumulated displacement. Each Link has a segment of relevance, which is assumed as infinitely rigid, that starts from the middle point between the considered and the previous Link and ends at the medium distance between the considered and the following Link. The distance between Links can be varied according to specific needs. Every node highlights a displacement referred to the previous one. By integrating the single contributes, it is possible to obtain the cumulate deformation. In addition to the calculation of local and cumulative displacements, the length of 7 convergence segments, connecting defined calculation points is determined. The algorithm calculates the coordinates of each point of interest using a clockwise, a counter clockwise or mixed weighted cumulative calculation, depending on the position of the node along the excavation profile.