摘要
利用改进的深层平板载荷试验装置对岳阳市城区典型的强风化、中风化和微风化软质板岩岩石地基进行8个场地26个试验点的现场岩基载荷试验,得到了相应的p-s,s-lgp和lgp-lgs曲线。试验结果表明:(1)p-s曲线均属缓变型,比例界限载荷不明显,但s-lgp曲线的第二拐点比较明显,可依此确定软质岩石地基的极限承载力;(2)强风化板岩岩石地基极限承载力较小且离散性极大,相应的最大沉降值较大且变化也大,而中风化板岩岩石地基极限承载力较大且较为稳定,对应的最大沉降值较小且变化也小,是桩基础良好的持力层;(3)卸载试验所获得的回弹值均较小。由此说明,软质板岩岩石地基在载荷作用下弹性变形阶段很短,其变形一开始就表现出非线性弹塑性特征,因而在对软质板岩岩石地基承载力进行理论计算或数值模拟时,采用非线性弹塑性本构关系更为合适。室内岩石试验结果表明,按岩石饱和单轴抗压强度乘以折减系数确定的岳阳市城区中风化软质岩石地基的承载力远低于岩石地基的实际承载力。根据规范提供的方法进行反算,得出了实际折减系数的建议值。
With the improved system from deep plate-bearing test, 26 in-situ static load tests are performed on the strong weathered soft rock, medium weathered soft rock and slight weathered soft rock in typical eight fields of Yueyang region, Hunan Province. The curves of p-s, s-lgp and lgp-lgs were drawn as follows： （1） All settlements curves of foundation change with static load laxly, and the limit loads of proportion are not obvious. However, the second inflection point of s-lgp curve is more obvious, which can be used to determine the ultimate bearing capacity of soft rock foundation. （2） The ultimate bearing capacity of strong weathered soft-rock foundation is smaller and more discrete than the others and the corresponding maximum settlement is greater and more discrete. But it is just opposite for the medium weathered soft-rock foundation and is a favorable bearing stratum for pile foundation. （3） All rebounded deformations when unloading are smaller, which indicate that the elastic deformation stage of soft slate rock foundation is considerably short under loading~ and the nonlinear elastoplasticity is notable at the beginning of deformation. So the constitutive relationship of nonlinear elastoplasticity is more suitable for theoretical calculation or numerical simulation of soft slate rock foundation. Experimental results show that the bearing capacity of medium weathered soft slate foundation from uniaxial compression strength of rock is much smaller than that from in-situ test. According to present codes, the suggestion value of reduction coefficient is put forward.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第5期953-959,共7页
Chinese Journal of Rock Mechanics and Engineering
基金
教育部留学回国人员科研启动基金项目(教外司留[2007]1108号)
湖南省科技攻关项目(2008FJ1023)
关键词
岩石力学
软岩
地基承载力
岩基载荷试验
折减系数
单轴抗压强度
rock mechanics
soft rock
bearing capacity of foundation
load test of rock foundation
reduction coefficient
uniaxial compression strength
