| Tunneling with pilot pipes is an advance supporting method that preventheading face collapsing and confine the surrounding rock applying to civilengineering, like tunnel, subway and highway. The steel floral pipe is a kind of steelpipe with hole that use to slip casting in the form of plum blossom. It used tostabilize and confine the soil, which acts as the critical part of the tunneling withpilot pipes. Due to the skill of construction members is not unanimous, and cheatingon workmanship and materials occur frequently. The quality and length of the steelfloral pipe can not meet the demand of load bearing strength. So it is very easily tocause casualties and property loss. As a new way of nondestructive testing,ultrasonic guided wave have been used in rod, pipe, plate widely. It has bigutilization potentiality in nondestructive testing of the steel floral pipe.For the purpose of the application of ultrasonic guided wave for tunneling withpilot pipes, propagation characteristics of ultrasonic guided wave in the steel floralpipe is studied in this paper. Main research activities are given as follows.(1) Propagation characteristics of ultrasonic guided wave T(0,1) mode in thesteel floral pipe is studied through finite element simulation. Finite elementsimulation model of T(0,1) mode propagation in the steel floral pipe is built. On thisbasis, after comparing the detection signal of T(0,1) mode testing steel floral pipe atseveral frequencies, the propagation characteristics of30kHz T(0,1) mode in steelfloral pipe is chosen to be studied. The effect of the hole number and the diameter ofholes of steel floral pipe on the signal amplitude and group velocity of T(0,1) modeat30kHz is investigated.(2) Experimental setup of T(0,1) mode testing the steel floral pipe is set up.Propagation characteristics of T(0,1) mode in steel floral pipe is studied inexperiments. Sensor which can stimulate T(0,1) mode is designed and processedeffectively. The effect of the hole number and the diameter of holes of steel floralpipe on the signal amplitude and group velocity of ultrasonic guided wave T(0,1)mode at30kHz is investigated by using this kind of developed sensers inexperiments. The comparison of the results in experiments and by using finiteelement simulation is conducted. The clamp is manufactured, which can make theprocess of senser installing more convenient. (3) Propagation characteristics of ultrasonic guided wave in the steel floral pipewith cement bond is studied in experiments. Sensor which can stimulate longitudinalmode is designed and manufactured effectively. The casting steel floral pipe is testedwith torsional mode and longitudinal mode. The effect of the length of the cementbond on the signal amplitude and group velocity of ultrasonic guided wave L(0,2)mode is systematically investigated at45kHz. |
