深厚软土地基堆土预压法观测与分析

Observation and analysis of a thick soft ground by preloading method

本文论述用30m深塑料排水板处理27m厚淤泥质粘土地基的工程实践。通过对两座5万m^3油罐地基堆土18m超载预压和充水17m复压测试，结果表明：塑料排水板的有效作用深度可达30m；预压后地基承载力可达340kPa、最大沉降量达3．36m，固结度95％。测试还表明：在含有“千层饼”薄层粉砂结构的淤泥质粘土中，插排水板后排水团结较快，可以每层30cm、每天1．5～2kPa的堆土速度，不间歇地一次加荷到位。安全控制应以沉降速率为主、水平位移速率为辅，其标准可分别采用20mm／d和4mm／d。

The ground of 27m thick mucky and silty clay treated with 30m deep prefabricated drain in combination with preloading was discussed in the paper. The test results of foundations of two oil tanks of 50 000m^3 which had been preloaded by 18m thick fill embankment and retested by 17m water-filling show that the effective depth of prefabricated drains can reach 30m,the bearing capacity can reach 340kPa after preloading,the maximum settlement of the ground is 3. 36m and the degree of consolidation reaches 95%.The tests also show that the pore water pressures resulted from filling are rather small in the thick soft clay with many silty sandy intercalations,so the safety monitoring of the ground should be carried out according to the rates of settlements and lateral displacements. Due to the rapid dissipation of pore pressure,the fill can be continuously proceeded to top in layers of 30cm thickness at a loading speed of 1. 5 to 2 kPa/d.