真空堆载联合预压地基沉降分析有关问题探讨

Discussion on Ground Settlement Analysis of Vacuum Stacking with Precompression

为研究真空联合堆载预压沉降规律并优化其分析方法,首先,分析堆载与真空预压的内在作用机理,进一步通过土力学理论分析堆载预压沉降计算方法;然后,通过现场监测试验分析手段,对真空预压地基内真空度衰减规律、真空预压的有效加固深度等进行研究,进而对其与堆载预压附加荷载传递规律、计算压缩层厚度的差异进行对比分析;最后,探讨真空堆载联合预压沉降分析的合理规定与计算方法。研究表明:(1)对于真空预压,竖向排水通道的作用,不限于缩短排水路径,更决定了真空预压的有效加固深度;(2)真空预压有效加固深度为塑料排水板打设深度,堆载预压的压缩层深度,以地基表面为起算面,采用附加应力与自重应力之比为0.1进行判定;地下水下降引起的压缩层深度可采用附加应力与自重应力之比为0.1计算,起算面为新的地下水位线;(3)对于真空堆载联合预压过程,可以看作真空荷载、堆载荷载分别预压的过程,可分别对其进行固结沉降分析,再进行叠加计算真空堆载联合预压的固结沉降,并通过修正计算其总沉降。

In order to study the law of ground settlement under vacuum preloading with precompression and optimize its analysis method, firstly, the internal mechanism of vacuum stacking is analyzed, and the calculation method of preloading settlement is further analyzed by the theory of soil mechanics. Secondly, through on-site monitoring and test analysis, the vacuum attenuation law in the vacuum preloading foundation is studied, the effective reinforcement depth of vacuum preloading is calculated, and then the difference about the additional load transfer law is analyzed, and the preloading and calculation of the thickness of the compression layer are carried out. After comparative analysis, the reasonable regulations and calculation methods of combined vacuum preloading and settlement analysis are discussed. Research results show:(1)For vacuum preloading, the role of vertical drainage channels is not limited to shortening the drainage path, but also it determines the effective reinforcement depth of vacuum preloading;(2)The effective reinforcement depth of vacuum preloading is the depth of the plastic drainage board. The depth of the compression layer of preloading is based on the surface of the foundation, and the ratio of the additional stress to the self-weight stress is 0.1 for judgment;the depth of the compression layer caused by the drop of groundwater can be determined by means of calculation with the ratio of additional stress to self-weight stress of 0.1, and the starting surface is the new groundwater level line;(3)For the combined preloading process of vacuum stacking, it can be regarded as the process of preloading the vacuum load and the stacking load respectively. The consolidation settlement analysis can be carried out separately, and then the consolidation settlement of the vacuum stacking with preloading can be superimposed to calculate the consolidation settlement and its total settlement through correction.