吹填流泥地基真空预压浅层加固需求研究

吹填流泥地基采用真空预压浅层加固的主要目的是为深层地基处理提供稳定的工作面,因此真空预压浅层加固后应避免深层地基处理时可能出现的垫层前沿滑动破坏、浅层加固区地基承载力破坏及由浅层加固区向下卧流泥的冲剪破坏等。根据深层地基处理时浅层加固区地基承载力破坏、由浅层加固区向下卧流泥抗冲剪破坏两种破坏模式推导得到真空预压浅层加固区不排水抗剪强度需求公式;深层地基处理垫层施工时前沿稳定需求的真空预压浅层加固区不排水抗剪强度应根据整体稳定性分析确定。分析表明,深层地基处理时浅层加固区地基承载力、抗冲剪需求的浅层加固区不排水抗剪强度与垫层厚度、深层处理施工机械、浅层加固厚度等有关;当深层处理垫层厚度超过1 m后,垫层前沿稳定需求的浅层加固区不排水抗剪强度急剧增大,且下卧流泥越厚,需要的抗剪强度越大。

Requirement of shallow improvement of foundation with dredged slurry by vacuum preloading

Since a stable platform for construction of improvement of deep soft strata is the principal aim of shallow improvement of foundation with dredged slurry by vacuum preloading,slide in front of cushion advance,bearing capacity failure,punching failure should be avoided during construction of improvement of deep soft strata.Equations of the undrained shear strength of shallow improvement of foundation with dredged slurry are derived accounting for the bearing capacity failure and punching failure during improvement of deep soft strata.The undrained shear strength of shallow improvement of foundation with dredged slurry required by the stability of cushion advance should be gotten through overall stability analysis.It is shown by analysis that the undrained shear strength of shallow improvement of foundation with dredged slurry accounting for the bearing capacity failure and punching failure relates to the thickness of cushion,construction equipments for treatment of deep soft strata and thickness of shallow improvement,etc.The undrained shear strength of shallow improvement of foundation with dredged slurry required by overall stability of cushion advance increases sharply along with the increase of thickness of cushion when the cushion thickness is more than 1 m.The underlying slurry is thicker,and the undrained shear strength of shallow improvement required by overall stability of cushion advance is greater.