Abstract
Due to the limitations of geography and geology, cast concrete tunnel anchors were used to provide counterforces for Xingkang Suspension Bridge foundation at the left bank of Daduhe River. In this study, the in situ creep tests were conducted on two model tunnel anchors at a scale of 1:10 near the real working anchor site. Thus, the long-term deformation of the real working tunnel anchors installed at the bridge foundation could be determined from the creep test of model tunnel anchors. The creep tests were conducted under three different loads and lasted for 102.2 h, 167.5 h, and 189.4 h, respectively. The model anchor, the surrounding rock, and their interface were all monitored and measured during the creep testing. In addition, the numerical calculation, in which the Burger creep constitution was used for describing the surrounding rock and the Mohr–Coulomb criterion for describing the concrete anchor, was performed to further evaluate the long-term stability of the real working tunnel anchors. The numerical calculations are in good agreement with the laboratory testing results, and the creep deformations of the anchor and the surrounding rock have the same order of magnitude. The results show that the tunnel anchor and surrounding rock of Xingkang Bridge are in a stable creep state under the three different loads.
Highlights
Introduction e XingkangBridge, located in Luding County of China, is a key engineering project of the Yakang Expressway connecting Ya’an City and Kangding City. e primary part of this bridge is a large-scale single-span steel truss suspension bridge with a length of 1100 m
In order to determine the creep characteristics of the tunnel anchor and the surrounding rocks, the in site creep tests of two model anchors were conducted. e creep tests comply with the similarity theory in physics. e gas–liquid hydraulic loading system was used for the creep testing method, and grating displacement sensors and dislocation meters were employed to monitor the creep deformation
Where Nm and Np are the loads applied on model tunnel anchor and real working anchor, respectively; C is a similarity constant, and the C-value is taken to be 10 in this study: lm where lm and lp are the geometric sizes of model tunnel anchor and real working anchor: Em Ep, (4)
Summary
In order to determine the creep characteristics of the tunnel anchor and the surrounding rocks, the in site creep tests of two model anchors were conducted. e creep tests comply with the similarity theory in physics. e gas–liquid hydraulic loading system was used for the creep testing method, and grating displacement sensors and dislocation meters were employed to monitor the creep deformation. In order to determine the creep characteristics of the tunnel anchor and the surrounding rocks, the in site creep tests of two model anchors were conducted. E creep tests comply with the similarity theory in physics. In order to avoid the influence of model tunnel anchor on the real working tunnel anchor in the process of the creep tests, the two model anchors were placed under the real anchors. E creep test of tunnel anchor model complies with the similarity theory in physics. E main parameters (strength, load, geometry, and elastic modulus) of the model anchor are determined from (1)–(4) referring to the paper by Lei et al [19]: Rm Rp,. Where Rm and Rp are the strengths of model tunnel anchor and real working anchor, respectively: Elevation (m) 930
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