Abstract: A non transitory computer readable medium and a method of detecting excavation of an underground tunnel, the method includes: propagating a light pulse through an underground optic fiber; generating detection signals responsive to Brillion scattered light resulting from the propagating of the light pulse through the underground optic fiber; wherein the detection signals represent tension values at multiple locations along the underground optic fiber; and processing the detection signals to detect excavation of the underground tunnel.

Abstract: A non transitory computer readable medium and a method of detecting excavation of an underground tunnel, the method includes: propagating a light pulse through an underground optic fiber; generating detection signals responsive to Brillion scattered light resulting from the propagating of the light pulse through the underground optic fiber; wherein the detection signals represent tension values at multiple locations along the underground optic fiber; and processing the detection signals to detect excavation of the underground tunnel.

Abstract: The present invention provides a new method for designing a multi layered pipe highly resilient to longitudinal bending, wherein the layer pipe includes an inner pipe, an outer pipe, and a separating layer. According to one embodiment the method includes the following of: determining the preferred ratio between inner and outer pipe radiuses, evaluating the external pressure developed by the surrounding soil in accordance with simplified linear model, calculating preferred stiffness and elastic for the separating material according to evaluated external pressure soil properties and determining the preferred composition of separating material according to calculated radiuses and calculated stiffness and elastic.