岩溶区钻孔桩泥浆漏失引起土体变形机制与破坏模式试验研究  

Model Test on Soil Deformation Mechanism and Damage Mode Caused by Mud Leakage from Drilled Piles in Karst Area

作　　者：姜明映 陈娥梅 刘永成 朱亚东 蒋文奎 谢瑞庭 JIANG Mingying;CHEN E’mei;LIU Yongcheng;ZHU Yadong;JIANG Wenkui;XIE Ruiting(Yunnan Qujing Transportation Construction Investment Group Co.,Ltd.,Qujing,Yunnan 655000,China;Fifth Engineering Company,China Railway Construction Bridge Engineering Bureau Group Co.,Ltd.,Chengdu,Sichuan 610500,China;School of Civil Engineering,Changsha University of Science&Technology,Changsha,Hunan 410114,China;Guangdong Yuehai Yuexi Water Supply Co.,Ltd.,Zhanjiang,Guangdong 524033,China)

机构地区：[1]云南省曲靖市交通建设投资集团有限公司,云南曲靖655000 [2]中铁建大桥工程局集团第五工程有限公司,四川成都610500 [3]长沙理工大学土木工程学院,湖南长沙410114 [4]广东粤海粤西供水有限公司,广东湛江524033

出　　处：《中外公路》2024年第5期59-64,共6页Journal of China & Foreign Highway

基　　金：国家自然科学基金资助项目(编号:52278329);湖南省交通运输厅科技项目(编号:202019,202247)。

摘　　要：岩溶区桩孔常常钻穿溶洞诱发泥浆漏失,引起孔壁失稳、地面塌陷、设备陷落,阻碍施工顺利进行。掌握钻孔因泥浆漏失而塌陷机制对优化、确定桩孔的施工工艺非常重要。该文采用室内模型试验,研究岩溶区覆盖层为上部黏土、下部砂土条件下桩孔钻穿溶洞、泥浆漏失引起土体变形机制与破坏模式,为岩溶区桩基施工方案决策提供试验依据。结果表明:桩孔钻穿溶洞顶板引起上部黏土、下部砂土覆盖层塌陷的力学原理是桩孔钻穿溶洞顶板后,泥浆快速下窜导致孔壁应力失去平衡,砂土因单粒结构而率先移动、充填桩孔,进而引起的上层黏土失稳下沉。当砂土顶面与水平面形成的夹角约等于内摩擦角时,砂土滑动停止;砂土滑动停止后,上层黏土下沉持续而形成土拱;土拱形成以后,地面趋于稳定;钻孔泥浆下窜诱发地面沉降的历程分为快速下沉、缓慢下沉、稳定3个阶段,整个过程历时约1 min,地面形成下沉盆。工程中,建议对溶洞顶板上部砂土采用注浆法加固,防止桩孔钻穿溶洞顶板引起地面塌陷,确保设备人员安全、施工顺利。Pile holes are often drilled through cavities in karst areas,which induces mud leakage and causes hole wall instability,ground collapse,or equipment trapping and hinders smooth construction.It is important to know the collapse mechanism of boreholes due to mud leakage,so as to optimize and determine the construction process of pile holes.In this paper,indoor model tests were used to study the deformation mechanism and damage mode of soil caused by drilling through cavities and mud leakage in pile holes under the conditions of upper clay and lower sandy soil in the karst area,so as to provide an experimental basis for the decision of pile construction plan in karst area.The results show that the mechanical principle of the pile hole drilling through the roof of the cavity and causing the collapse of the upper layer of clay and the lower sand covering layer is that after the pile hole drills through the roof of the karst cavity,the mud quickly goes down and causes the stress of the hole wall to lose balance,and the sand first moves and fills the pile hole due to the single grain structure,which causes the instability and sinking of the upper layer of clay.When the angle between the top surface of the sand and the horizontal surface is about equal to the angle of internal friction,the sand sliding stops.After the sand sliding stops,the upper layer of clay sinks continuously and forms the soil arch.After the soil arch is formed,the ground tends to be stable.The process of ground sinking induced by drilling mud channeling can be divided into three stages:rapid sinking,slow sinking,and stabilization.The whole process takes about one minute.The ground forms a sinking basin.In the project,it is suggested to reinforce the sand on the top of the roof of the karst cavity by grouting to prevent the ground collapse caused by the pile hole drilling through the roof of the karst cavity,and then the safety of the equipment or personnel and smooth construction can be ensured.

关 键 词：基础工程 岩溶 桩孔垮塌 地面塌陷 泥浆下窜 模型试验 

分 类 号：U416[交通运输工程—道路与铁道工程]