溶洞型基桩承载特性离心试验及承载力计算方法  

Bearing Characteristic Centrifugal Test and Bearing Capacity Calculation Method of Pile Passing Through Karst Cave

作　　者：陈慧芸[1] 冯忠居[1] 夏承明 刘旭照 王逸然 Chen Huiyun;Feng Zhongju;Xia Chengming;Liu Xuzhao;Wang Yiran(Highway School,Chang'an University,Xi'an 710064,P.R.China;Sanming Puyan Expressway Co.Ltd.,Sanming,Fujian 365000,P.R.China)

机构地区：[1]长安大学公路学院,西安710064 [2]三明莆炎高速公路有限责任公司,福建三明365000

出　　处：《地下空间与工程学报》2023年第3期856-866,880,共12页Chinese Journal of Underground Space and Engineering

基　　金：国家重点研发计划项目(2018YFC1504801);福建省交通运输厅科技攻关项目(2018Y032)。

摘　　要：为确定溶洞对基桩荷载传递规律和承载特性的影响,通过离心模型试验,研究了4种洞高、4种洞跨和3种溶洞层数下基桩的荷载-沉降规律、竖向承载力、荷载分担比、轴力和侧阻的变化;引入敏感分析模型,研究了基桩竖向承载力对两因素的敏感性;采用荷载传递法建立了穿过溶洞的基桩荷载-沉降计算公式。结果表明:洞高、洞跨、层数的增加会削减基桩竖向承载力,洞高对承载力的影响大于洞跨;两因素变化下溶洞处桩身轴力几乎不衰减,单位侧阻骤减至接近零;采用改进的荷载传递法和双曲线模型建立了基桩承载力计算公式,计算结果与试验结果相比,最大误差5.96%,具有较高吻合度。研究成果可为岩溶区基桩竖向承载力和沉降计算提供参考。The influences of karst cave on load transfer law and bearing characteristics of pile passing through karst caves are investigated.The variation of load-settlement law,vertical bearing capacity,load sharing ratio,axial force and lateral resistance of pile passed through karst caves of 4 different heights,4 different spans,and 3 caves layers are studied by centrifugal model test.The sensitivity analysis model was introduced to study the sensitivity of vertical bearing capacity of pile to two factors.The load-settlement calculating formulas of pile passing through karst caves were established by load transfer method.The results reveal that increasing the height,span,and number of caves all have detrimental effects on the vertical bearing capacity of pile,and the influence of height on bearing capacity is greater than that of span.The pile axial force almost keeps unattenuated and unit lateral resistance decrease suddenly to zero under the change of two factors.Based on the improved load transfer method and hyperbolic model,the calculation formula of pile bearing capacity is established.Compared calculation results with test results,the maximum error s only 5.96%,which has a high coincidence degree.The study can provide references for calculating vertical bearing capacity and settlement of pile in karst area.

关 键 词：岩溶区 基桩 承载特性 离心模型试验 荷载传递法 

分 类 号：TU43[建筑科学—岩土工程]