推扭(H-T)荷载作用下刚性矩形基础承载特性研究

Study on bearing characteristics of rigid rectangular foundation subjected to horizontal force and torque(H-T)

现行杆件基础设计仅考虑水平力(H)而忽略扭矩(T)的作用,这很可能导致杆件基础发生推扭破坏。为分析推扭(H-T)荷载下刚性矩形基础的承载特性,首先根据杆件基础的受力特点,建立了相应的简化计算模型,推导了T、H-偏心弯矩(M)2种承载模式下基础受力与变形分析的理论解答;其次通过数值模拟分析,获得了H-T荷载下矩形刚性基础的破坏包络线;在此基础上,通过室内模型试验验证了理论计算方法的合理性,并探讨了扭推比、地基抗力比例系数m值对基础受力与变形的影响。研究发现:H-T荷载下刚性矩形基础的破坏包络线近似呈抛物线分布;随扭推比增大,矩形基础的地基承载力随之减小,其破坏模式也由水平变形破坏转为扭转变形破坏;增大m值,可有效减小基础地面处水平位移及旋转角度。为确保刚性矩形基础的安全稳定,其上覆回填土体性质和压实度均应满足设计要求。上述结论可为多杆合一杆件基础的设计提供参考。

The current design of member foundation only considers horizontal forces(H)and ignores the effect of torque(T),which may lead to torsional failure of the foundation.To analyze the bearing characteristics of rigid rectangular foundation subjected to horizontal force and torque(H-T),according to the stress characteristics of the foundation,the corresponding simplified calculation model is established,and the theoretical solutions of the stress and deformation analysis of the foundation under the two bearing modes of torque(T),horizontal force(H)-eccentric bending moment(M)are derived;numerical simulation analysis is carried out to obtain the failure envelope of rigid rectangular foundations under push torsion H-T load.And then the rationality of the theoretical calculation method is verified by the indoor model test.Finally,the influences of torsion ratio and foundation resistance ratio coefficient m on the stress and deformation of foundation are analyzed.The results show that the failure envelope of rigid rectangular foundation under push torsion H-T load is approximately parabolic.With the increase of torsion-thrust ratio,the horizontal bearing capacity of the foundation decreases,and its failure mode changes from horizontal deformation failure to torsional deformation failure.The increase of the proportional coefficient m can reduce the horizontal displacement and rotation angle at the foundation ground effectively.To ensure the safety and stability of the rigid rectangular foundation,the nature and compaction of the overlying backfill should satisfy the design requirements.This study can provide basic information for the design of multi-rod unified rod foundations.