Hiroyuki Ozawa
Calculation method on shield segment rolling by geometric condition and its application
Mitsutaka Sugimoto
Recently, constructions of road with sharp curve and steep slope increase. In the case of a combined tunnel alignment, the rolling of segments due to geometric conditions needs to be considered. Therefore, this paper aims to develop the calculation method on the amount of segment rolling.
The procedure of the calculation method on the rolling angle of segment is as follows:
1)The torsion ¦Ó , which is defined as the rate of turning with respect to arc length of the osculating plane about the tangent of a space-curve, can be calculated from the change of binormal unit vector per unit curve length. Here the binormal vector can be obtained from a tangential vector and a principal normal vector, which are defined by radius of curvature and gradient;and
2)The rolling angle of segments can be obtained by the integration of ¦Ó with respect to total arc length. Furthermore, based on this method, the required allowance in circumferential direction of ring joint hole was obtained from the torsion, the radius of segment, and the width of segment.
As a result, the followings were confirmed:
1)Torsion is not generated in the case that lining alignment is on a two dimensioned plane, such as, horizontal plane and vertical one;
2)The combination of sharp curve and steep slope causes the larger torsion; and
3)Since the usual allowance of ring joint hole is 3mm, the rolling of segments due to geometric conditions should be examined at segment design, when the radius of curvature of tunnel is less than 100m and the gradient of tunnel is larger than 5%.
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