就地固化表层地基承载特性现场试验研究

Field test on bearing characteristics of surface foundation by in-situ stabilization

以浙江省31省道北延线绍兴市区路段地基处理为例,研究两种原位固化地基处理方式(ALLu强力搅拌头搅拌法和国产自制设备与ALLu强力搅拌头联合应用)的适用性及其处理效果,针对两种地基处理方式进行现场平板载荷试验、无侧限抗压强度试验、标准贯入试验和静力触探试验。为得到就地固化处理后地基应力和地基变形的规律,在地基处理路段布置土压力盒和沉降板进行现场监测试验。试验结果表明:与传统的换填法相比,就地固化处理后的地基承载力提高至少30%;固化养护龄期28 d时,原位固化土的无侧限抗压强度与室内无侧限抗压强度之比在0.35~0.65之间;标准贯入试验和静力触探试验均表明原位固化处理后地基土的强度提高,且计算的地基承载力与平板载荷试验实测结果相差不大,均可以作为就地浅层固化地基处理技术的检测指标;对两组路段的应力和附加应力系数进行分析发现,经原位固化形成的人工硬壳层具有较好的扩散应力作用。

Based on the ground treatment of the north extension of No.31 provincial road in the urban section of Shaoxing in Zhejiang Province,the feasibility and treatment effect of two methods,i.e.,ALLu strong stirring head stirring method with homemade equipment and ALLu strong stirring head combined application,by in-situ curing foundation treatment were studied.Plate loading test,unconfined compressive strength(UCS)test,standard penetration test and static cone penetration test were carried out,respectively.Meanwhile,in order to obtain the stress and deformation of the in-situ curing foundation,field monitoring was carried out by arranging the earth pressure box and settlement plate.The test results showed that the bearing capacity of foundation by insitu curing were increased by at least 30%compared with the traditional replacement method.At 28 days of curing time,the ratio of UCS of curing soil in-situ to that of indoor value was 0.35-0.65.The bearing capacity of foundation was improved by standard penetration test and static cone penetration test,and the calculating bearing capacity were consistent with the measured results of plate loading test.The stress and additional stress coefficient of the two groups of road sections were analyzed,and the artificial crust layer had better effect on the diffusion stress,which can be used for detection of in-situ shallow stabilization in engineering practice.