钻孔灌注桩桩头静态破碎原理与裂纹发展机理  

Static Crushing Principle and Crack Development Mechanism of Bored Cast-in-place Pile

作　　者：李小龙 关盛杰 高帅 王彦军 刘世强 孔德森 LI Xiao-long;GUAN Sheng-jie;GAO Shuai;WANG Yan-jun;LIU Shi-qiang;KONG De-sen(Qingdao Institute of Geological Exploration, China Metallurgical Geology Bureau, Qingdao 266061, China;School of Civil Engineering and Architecture, Shandong University of Science and Technology, Qingdao 266590, China;Shandong Key Laboratory of Civil Engineering Disaster Prevent and Mitigation, Shandong University of Science and Technology, Qingdao 266590, China;Shandong Zhengyuan Construction Engineering Co., Ltd., Jinan 250101, China)

机构地区：[1]中国冶金地质总局青岛地质勘查院,青岛266061 [2]山东科技大学土木工程与建筑学院,青岛266590 [3]山东科技大学山东省土木工程防灾减灾重点实验室,青岛266590 [4]山东正元建设工程有限责任公司,济南250101

出　　处：《科学技术与工程》2021年第22期9549-9553,共5页Science Technology and Engineering

基　　金：山东省自然科学基金(ZR2019MEE027);中国冶金地质总局山东局青年科技基金(2020-19-9)。

摘　　要：静态破碎技术近年来在混凝土构筑物的拆除中得到了广泛应用,将该技术应用于钻孔灌注桩桩头的破除是一种新的破除方案,可以避免粉尘和噪音污染。为了分析桩头静态破碎过程中的应力分布和裂纹发展规律,利用RFPA 2D软件建立了桩头裂纹发展数值计算模型,得到了一些重要结论。结果表明:静态破碎是一个持续发展过程,当膨胀压达到混凝土抗拉强度,裂纹开始产生,随着膨胀压的增大,在尖端应力的作用下,裂纹得以继续发展;当膨胀孔直径为40 mm时,在灌注破碎剂大约7 h后膨胀压达到20 MPa,混凝土开始产生裂纹;膨胀孔裂纹大致呈两条或三条形式发展,一条伸向最小抵抗线方向,其余指向相邻膨胀孔。对于直径为600 mm和800 mm的桩头静态破碎工程,采用“核心1孔+环形均布6孔”的布孔方式,可获取较好的破碎效果。Static crushing technology has been widely used in the demolition of concrete structures in recent years.The application of this technology to the head breaking of bored pile is a new method,which can avoid dust and noise pollution.In order to analyze the stress distribution and crack development law in the static crushing process of pile head,the numerical calculation model of crack development of pile head was established by using RFPA2D software,and some important conclusions are obtained.The research results show that the static crushing is a continuous development process,when the pressure reaches the concrete compressive strength,crack began to produce,with the increase of swelling pressure,in tip stress,under the action of the crack to continue development;When the diameter of the expansion hole is 40 mm,the expansion pressure reaches 20 MPa about 7 h after the pouring of the expansion agent,and the concrete begins to crack.The crack in the expansion hole develops in two or three forms,one of which extends to the direction of the minimum resistance line,and the others point to the adjacent expansion hole.For the static crushing project of pile head with diameter of 600 mm and 800 mm,the hole arrangement method of‘1 hole in core+6 holes in circular uniform distribution’can obtain better crushing effect.

关 键 词：钻孔灌注桩 静态破碎 裂纹发展机理 桩头破除 

分 类 号：TU470.3[建筑科学—结构工程]