依据现场监测数据评价城市道路软土地基处理效果

Evaluation of Soft Foundation Treatment of Urban Road Based on Field Monitoring Data

为评价软基处理效果,确定合理的卸载时间,选取典型监测断面的地表沉降、超孔隙水压力及十字板剪切强度数据进行分析研究。结果表明:在软土地基总沉降量中,填土加载期占主要部分,接近于60%,预压期的沉降量占总沉降量35%左右;推测软土地基工后沉降的结果证明,预压期前三个月,推测的工后沉降大于30 cm,此后随着堆载预压时间的增加,推测的工后沉降逐渐减少,但表现的并不十分明显;整个填土加载期,超孔隙水压力变化过程呈现出波浪型的变化,浅层大于深层的超孔隙水压力,随着堆载预压时间的增加,软土地基中,不同深度的超孔隙水压力逐渐减小,并逐渐接近;软土层经过预压排水固结,抗剪强度有个明显增加的过程,预压卸载前比排水固结前的十字板剪切强度增加6~8k Pa,抗剪强度增长率会随着剪切深度的增加而减少,增长率在26.3%~91.0%之间。研究成果为今后本区域的软基设计和施工提供可靠的依据。

In order to evaluate the effect of soft foundation treatment and determine the reasonable unloading time,the surface settlement,excess pore water pressure and cross shear strength data typical monitoring section were selected and analyzed.Results show that：in the total settlement of soft soil foundation,the filling period was the main part,which was close to 60%,and the settlement of the preloading period accounts for about 35%.It was assumed that the post construction settlement of soft soil foundation proves that the settlement after construction was greater than 30cm in the first three months of the preloading period.Then,with the increase of the preloading time,the post-construction settlement decreased,but the performance was not very obvious.During the whole loading period,the change of excess pore water pressure showed a changed of the wave type,and the pressure in shallow layer was larger than that in deep layer.With the increase of surcharge preloading time,the excess pore water pressure at different depths decreased gradually and gradually approaches in soft soil foundation.In the soft soil layer,the shear strength increased obviously by preloading drainage consolidation,and the shear strength of the cross plate before preloading was increased by 6-8 kPa,compared with that before the drainage consolidation.The shear strength growth rate would decrease with the increase of shear depth,and the growth rate was between 26 3% and 91 0%.The research will provide a reliable basis for the design and construction of soft soil in this region.