初始孔压非均布条件下散体材料桩复合地基固结理论研究

Study of consolidation theory of composite ground with granular columns under nonuniform distribution of initial excess pore water pressure

针对现有复合地基固结理论仍不能考虑实际工程中存在的初始孔压非均布情况的不足,采用解析方法对散体材料桩复合地基进行深入研究,给出了考虑初始孔压非均布的散体材料桩复合地基固结一般解。探讨了初始孔压非均布的3种特殊情况,导出了初始孔压矩形分布(均布)、正三角形分布和倒三角形分布等情况下的复合地基平均孔压和平均固结度表达式。研究表明:单面排水条件下,初始孔压分布对复合地基固结有显著影响;初始孔压均布和正三角形分布条件下,超静孔压随Tv值的增大而逐渐消散,固结期间地基底部孔压值最大;初始孔压倒三角形和梯形(pB/pT=0.5)分布条件下,Tv值越大,孔压等时线越平缓,且孔压最大值的位置由地基顶部向底部转移,固结过程中底部孔压变化呈现"从小变大、再变小"的特点。

Aiming at the shortcoming of the existing consolidation theories of composite ground without considering nonuniform distribution of initial excess pore water pressure in practical engineering,the consolidation theory of composite ground with granular columns is studied in-depth by analytical method;and a general analytical solution is given to the consolidation problem for the composite ground with granular columns under nonuniform distribution of initial excess pore water pressure.The three special cases for nonuniform distribution of initial excess pore water pressure are discussed;and the expressions of average excess pore pressure and average degree of consolidation are derived under the rectangular（uniform）,triangle and inverted triangle distribution of initial excess pore pressures.The results show that the distribution of initial excess pore water pressures has obvious influence on the consolidation of the composite ground with single drainage boundary.Under the uniform and triangle distribution of initial excess pore pressure,the excess pore water pressure dissipates gradually with the increase of Tv,and the one is always maximal at the bottom of foundation during consolidation;under the inverted triangle and trapezoidal（pB /pT =0.5） distribution of the initial pore water pressure,the Tv value is bigger,the excess pore water pressure isochrones are gentler,and the position of maximal excess pore pressure shifts from the top of foundation to the bottom;the change of excess pore water pressure reflects the characteristic ＂from small to big,and then smaller＂ in the consolidation process.