北京通州地区旁压试验估算水平基床系数的探讨

Estimation of Horizontal Bed Coefficient by Pressuremeter Test in Tongzhou Area, Beijing

水平基床系数是地下工程设计的重要参数,其数值的准确性关系到工程的安全性和经济性,由于技术原因水平基床系数是比较难确定的参数,旁压试验作为一种原位试验,应力应变关系清晰,估算水平基床系数具有很好的可靠性。在通州地区0~100m深度范围内,针对黏性土及砂土,采用旁压试验法估算水平基床系数。结果表明:通过对0~100m深度范围内粉质黏土及砂土旁压试验,标准贯入试验获取的基床系数和规范经验值进行对比,可以采用旁压试验引进折减系数获取水平基床系数。30m以上可塑粉质黏土,修正系数可取0.23,30~80m密实砂土修正系数可取0.15,80m以下可塑-硬塑粉质黏土修正系数可取0.20。

Horizontal bed coefficient is an important parameter in underground engineering design,and the accuracy of its numerical value is related to the safety and economy of the project.Because of technical reasons parameters are difficult to determine.As a kind of in situ testing,the stress-strain relationship of pressuremeter test is clear,and it is reliable to estimate the horizontal coefficient of subgrade reaction.In the depth of 0-100 meters in Tongzhou area,a method for estimating the horizontal coefficient of subgrade reaction by pressuremeter tests on cohesive soil,silt and sandy soil in Tongzhou area has been obtained.By comparing the horizontal coefficient of subgrade reaction and standard experience value obtained by pressuremeter test and standard penetration test of silty clay and sand in the depth range of 0~100 m,we can obtain the horizontal coefficient of subgrade reaction by using pressuremeter test and reduction coefficient.For plastic silty clay of over 30 meters,the correction factor may be taken as 0.23;for dense sand of 30~80 meters,the correction factor as 0.15;for plastic hard plastic silty clay of below 80 meters,the correction factor as 0.20.