采空区建筑地基适宜性及沉降变形计算工程实例分析

基于稳定采空区场地并结合某一工程实例进行建筑地基沉降变形计算分析，并对采空区地基适宜性进行综合评判。提出一种适合于采空区地基的荷载影响深度 确定方法，采用概率积分法对采空区场地不同区域剩余变形进行预测，提出考虑活化变形、剩余变形、附加变形的采空区建筑地基沉降变形计算方法，研究结果表明：（1）建筑荷载相同时判别系数越小（0.10 （自重应力）、0.08 、0.07 、0.05 ），荷载影响深度越大；判别系数相同时建筑荷载越大，荷载影响深度也随之非线性增大。（2）对于一般采空区地基，宜采用 （附加应力）= 0.10 判别标准确定荷载影响深度；对于复杂采空区地基，宜采用 0.05 判别标准确定荷载影响深度。（3）在常规方法上（ 0.20 ）确定的荷载影响深度 ，对于采空区地基经对比分析，1.4 和1.8 荷载影响深度可作为一般采空区地基和复杂采空区地基工程设计参考。（4）在不引起活化变形的最高层数建筑荷载下，地表剩余变形量非常小可忽略不计，采空区建筑地基沉降变形主要是土层附加压缩变形。（5）数值模拟结果表明，采空区内边缘沉降较大、不均匀沉降明显，不宜作为建设场地；采空区中央沉降较小，没有明显不均匀沉降，宜作为建设场地。

Case study on suitability and settlement of foundation in goaf site

The settlement of foundation in stable goaf site is analyzed to evaluated its suitability. One calculation method of load influence depth for goaf ground is proposed. The residual deformation of goaf ground is predicted by the probability integral method, and the settlement calculation method of building ground on goaf is put forward considering the activated deformation, the residual deformation and the additional deformation. Research results show that: 1) The less the coefficient of standard (0.10 (self-weight stress of ground), 0.08 , 0.07 , 0.05 ) under the same building load, the greater the influence depth. The larger the building load under the same coefficient, the influence depth is increased non-linearly. 2) The standard of (additional stress of ground) = 0.10 should be used to determine the influence depth for normal goaf ground, and the standard of 0.05 for complicated goaf ground. 3) The influence depth is determined by the conventional standard ( 0.20 ), and the 1.4 and 1.8 can be used as goaf building design for the normal goaf and complicated goaf. 4) The residual deformation of goaf ground is very small and can be negligible under the maximum building load without the activated deformation, and the settlement deformation of building ground is mainly the additional compression deformation. 5) Numerical results show that the ground settlement at the edge of goaf is large, and its uneven settlement is obvious, so the edge of goaf is not suitable as construction sites; however, the ground settlement at the central of goaf is small, and there is no obvious uneven settlement, so the central of goaf is suitable as construction sites.