摘要
城市地铁隧道施工中经常遇到新建隧道下穿上方已建隧道的例子,如何提前预测已建隧道的纵向变形是目前工程界普遍关心的问题。基于能够考虑土体变形连续性的Kerr地基梁理论,分别将已建隧道简化为欧拉伯努利梁和铁木辛柯梁,将新建隧道对已建隧道的作用简化为高斯分布荷载,建立了新建隧道施工对上方已建隧道影响的解析分析方法;并利用离心机试验结果进行了验证。分析了地层损失率、荷载形状参数和隧道与土体相对抗弯刚度对已建隧道纵向变形的影响。探讨了隧道剪切刚度对隧道纵向变形的影响。研究发现,当隧道剪切刚度趋于无穷大时,Kerr地基上的铁木辛柯梁退化为欧拉伯努利梁;对于抗弯刚度较大的隧道(如抗弯刚度大于7.54×106kN·m2),Kerr地基梁具有较好的适用性;已建隧道的剪切刚度对其纵向变形何纵向曲率产生显著影响;当隧道等效剪切刚度有效系数≤1/4时,必须考虑隧道剪切刚度对隧道纵向变形的影响。将所提分析方法应用于上海盾构隧道穿越工程中,并与现场实测结果进行对比,验证了方法的合理性。
The effect of underlying tunneling on existing tunnel is of great concern because the newly built tunnel can induce longitudinal deformation of existing tunnels. A prediction model based on the method of beam on Kerr elastic foundation is proposed. The existing tunnel is simplified as Euler-Bernoulli beam and Timoshenko beam, respectively, to consider the effect of the tunnel shear stiffness on the longitudinal settlement caused by the underlying tunneling. The impact of underlying tunneling on the existing tunnel is taken as Gauss-distributed loading. The proposed prediction method is then verified with the centrifuge results from the reference. The effects of volume loss, load distribution, relative bending rigidity between shield tunnel and ground and tunnel shear strength on the longitudinal settlement of existing tunnel caused by underlying tunneling are investigated, respectively. The results of Timoshenko beam are consistent with those of Euler-Bernoulli beam when the tunnel shear strength is big enough. The proposed method is more feasible for the tunnel with the bending rigidity greater than 7.54＆#215;106kN＆#183;m2. The effect of tunnel shear strength is very significant when the equivalent shear strength ratio is less than 1/4. The proposed method is finally validated using the field monitoring in Shanghai.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2014年第9期2659-2666,共8页
Rock and Soil Mechanics
基金
国家科技支撑计划资助项目(No.2012BAJ01B02)
国家自然科学基金(No.51278381)
上海市优秀学术带头人计划(No.12XD1405100)
关键词
盾构掘进
Kerr地基模型
纵向变形
剪切刚度
shield tunneling
Kerr foundation model
longitudinal deformation
shear stiffness
作者简介
张冬梅，女，1975年生，博士，教授，主要从事岩土力学与工程方面的教学与研究工作。E-mail：dmzhang@tongji．edu．cn
