摘要
目前桩锚围护结构是基坑工程常用的支护方式,在岩溶地层进行施工时常会遇到长锚索穿越溶洞的情况。溶洞填充物的力学性质与一般地层相差较大,长锚索锚固力会有一定程度降低,进而对地铁基坑的稳定性产生不利影响。以徐州地铁2号线淮塔东路站基坑工程为背景,针对岩溶地层长锚索穿越溶洞时锚固力的计算问题,通过对比分析岩溶地层与一般地层长锚索的受力特征,考虑锚索穿越溶洞时剪应力的折减,建立长锚索穿越溶洞锚固力的计算模型。进而基于剪切位移法原理,采用荷载传递法,推导得到相应的长锚索锚固力计算方法。该计算方法得到的理论值与实测值吻合较好,从而验证了计算方法的可靠性。分析溶洞直径、锚固始端距溶洞距离及溶洞填充物剪切模量对长锚索锚固力的影响规律。研究结果表明:当溶洞直径不变时,溶洞距锚固始端距离越远,锚索锚固力越大,当溶洞分布在距锚固始端较近的位置(4 m内)时,锚固力的值受溶洞的影响很大,在此之外的溶洞影响较小;当溶洞与锚固始端距离不变时,溶洞直径越大,锚索锚固力越小;当溶洞直径及溶洞与锚固始端距离均不变时,溶洞填充物剪切模量越大,锚索锚固力也越大。当溶洞填充物的剪切模量较小时,采用注浆方式填充溶洞可有效提高长锚索的锚固力。
Pile-anchor retaining structure is a common supporting method in foundation pit engineering, and long anchor cables often pass through karst caves during construction in karst strata. The mechanical properties of the cave filling are much worse than those of the general layer, so the anchoring force of the long anchor cable will be reduced, which will adversely affect the stability of the subway foundation pit. The foundation pit project of Xuzhou Metro Line 2 Huaita East Road Station was taken as the engineering background, and the calculation problem of the anchorage force of long anchor cable crossing karst cave in karst layer was considered. This paper established a calculation model of the anchorage force of long anchor cable crossing karst cave by comparing the stress characteristics of long anchor cable in karst layer and general layer and considering the reduction of shear stress in karst layer. Based on the principle of shear displacement method and load transfer method, the calculation method of anchorage force of long anchor cable was derived. The theoretical values obtained by this calculation method were in good agreement with the measured values, which verified the reliability of the calculation method. Finally, the influences of the diameter of the cave, the distance from the anchorage start, and the shear modulus of the cave filling on the anchorage force of the long anchor cable were analyzed. The results show that when the diameter of the cave is constant, the farther the cave is from the anchorage beginning of the anchorage, the greater the anchorage force is. When the cave is close to the beginning of the anchorage(within 4 m), the anchorage force is significantly influenced by the cave and the cave outside is less influenced. When the distance between the cave and the anchorage end is constant, the larger the cave is, the smaller the anchorage force is. When the diameter of the cave and the distance between the cave and the anchorage end remain unchanged, the long anchor cable gradually incre
作者
肖国庆
施成华
叶承敏
孙晓贺
宋银涛
郑可跃
XIAO Guoqing;SHI Chenghua;YE Chengmin;SUN Xiaohe;SONG Yintao;ZHENG Keyue(School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2023年第2期641-650,共10页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(52178402)。
关键词
岩溶地层
荷载传递法
剪切位移法
锚固力
Karst stratum
load transfer method
shear displacement method
anchorage force
