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Statistical Analysis on Temporal and Spatial Characteristics of the Axial Force of Anchor Bolts in Tunnelling
(1 Key Laboratory of Urban and Engineering Safety and Disaster Reduction of the Ministry of Education, Beijing University of Technology, Beijing 100124; 2 Zhejiang Province Institute of Architectural Design and Research, Hangzhou 310006)
Abstract Based on the statistical data of axial forces of 282 anchor bolts in 68 monitoring sections of 33 tunnels, this paper investigates the overall distribution characteristics of the axial force of anchor bolts and the influence law of surrounding rock grades on it, discusses the time-history variation characteristics and spatial distribution law of the axial force of anchor bolts, studies the relationship between the axial force and the length of anchor bolts, as well as analyzes the influence law of tunnel excavation radius on the position of maximum axial force of anchor bolts,thus revealing the relationship between the neutral point of anchor bolts and the tunnel excavation radius. The results show that: the longer the anchor bolt length and the higher the surrounding rock grade, the longer it takes to reach the maximum axial force value of anchor bolts, and the time-history curve of the axial force is divided into three stages: the rapid increase stage, slow fluctuation stage and stabilization stage; from the perspective of spatial distribution law, the distribution of the axial force of anchor bolts is relatively discrete, but the maximum value often appears at the tunnel spandrel and haunch; the proportion of occurrence of the larger axial force increases with the increase of anchor bolt length; and the neutral point position of anchor bolts increases linearly with the increase of tunnel excavation radius.
Abstract：
Based on the statistical data of axial forces of 282 anchor bolts in 68 monitoring sections of 33 tunnels, this paper investigates the overall distribution characteristics of the axial force of anchor bolts and the influence law of surrounding rock grades on it, discusses the time-history variation characteristics and spatial distribution law of the axial force of anchor bolts, studies the relationship between the axial force and the length of anchor bolts, as well as analyzes the influence law of tunnel excavation radius on the position of maximum axial force of anchor bolts,thus revealing the relationship between the neutral point of anchor bolts and the tunnel excavation radius. The results show that: the longer the anchor bolt length and the higher the surrounding rock grade, the longer it takes to reach the maximum axial force value of anchor bolts, and the time-history curve of the axial force is divided into three stages: the rapid increase stage, slow fluctuation stage and stabilization stage; from the perspective of spatial distribution law, the distribution of the axial force of anchor bolts is relatively discrete, but the maximum value often appears at the tunnel spandrel and haunch; the proportion of occurrence of the larger axial force increases with the increase of anchor bolt length; and the neutral point position of anchor bolts increases linearly with the increase of tunnel excavation radius.
LI Pengfei1 HUANG Jingluo1,
2 CHEN Keyi1 TONG Lei2
.Statistical Analysis on Temporal and Spatial Characteristics of the Axial Force of Anchor Bolts in Tunnelling[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(5): 227-236
2021, Vol. 58 