预应力混凝土实心方桩锤击施工入岩纵向裂缝研究

发布时间：2018-04-05 11:54

本文选题：预应力桩　切入点：纵向裂缝　出处：《中国石油大学(华东)》2015年硕士论文

【摘要】：随着半岛蓝色经济区等国家战略的实施,在未来的几年内,山东将兴建大量公共建筑和港口码头等建筑与设施,桩基础作为一种传统的基础型式,它的需求将会是空前的。预应力混凝土实心方桩以其混凝土强度高、抗裂、抗弯和抗腐蚀性能好、入岩穿透能力强、对地质条件适应性强等优点被广泛用于工业与民用建筑、铁路、码头、港口、市政等地基基础工程中的桩基础工程。对此,本文作者导师课题组与青岛昊河水泥制品有限责任公司共同研制了预应力混凝土实心方桩(以下简称方桩),编制并被批准为山东省标准设计图集(《预应力混凝土实心方桩》(图集号:L13SG410))。然而由于山东地区地理环境影响,地层中有许多碎石类土层、细粒花岗岩、强风化岩和煌斑岩等,导致了方桩在采用锤击沉桩施工时易出现纵向裂缝,这会严重影响结构的耐久性和桩基的稳定性,特别山东半岛,具有特殊酸性腐蚀介质侵蚀的地质条件,其危害是无法想象的。针对以上问题,本文采用LS-DYNA非线性有限元程序,取图集中的方桩为对象,研究了锤击施工入岩时纵向裂缝的成因以及探讨图集中方桩的相关设计在控制纵向裂缝方面达到的深度和质量的要求,结论如下:(1)打桩时产生的横向拉应力过大,超过混凝土抗拉强度设计值是产生纵向裂缝的原因;(2)桩尖穿过坚硬的夹层或持力层时,桩身两端最容易出现纵向裂缝,图集中设计的锥形桩尖、桩套箍和桩身两端加密螺旋箍筋可以很好的限制纵向裂缝;(3)桩身混凝土有效预压应力可以抵消打桩时产生的纵向拉应力,不必担心横向裂缝的产生;(4)合适厚度和刚度的垫层可以显著改善方桩抗裂性能,此外施工时要及时更换垫层。
[Abstract]:With the implementation of the national strategy of blue Peninsula Economic Zone, in the next few years, Shandong will build a large number of public buildings and ports, buildings and facilities, pile foundation as a traditional foundation form, its demand will be unprecedented. Prestressed concrete solid pile with high strength concrete, anti cracking. Bending and good corrosion resistance, strong ability to penetrate into the rock, the advantages of strong adaptability for geological conditions etc. it is widely used in industrial and civil construction, railway, port, wharf, pile foundation engineering of municipal foundation engineering. In this regard, the author of this paper and research group supervisor of Qingdao Hao River Cement Products Co. Ltd. jointly developed the prestressed concrete solid pile (hereinafter referred to as the square pile), prepared and approved as Shandong province standard design atlas (< > prestressed concrete solid pile (atlas No. L13SG410)). However, due to geographical area of Shandong The environmental impact, there are a lot of gravel soil, formation of fine grained granite, weathered rocks and lamprophyres, resulting in the pile hammer pile sinking construction to longitudinal cracks, which will seriously affect the stability of the structure and durability of pile foundation, especially the Shandong Peninsula, with the special geological conditions of erosion of acid corrosion medium, the harm is unimaginable. Aiming at the above problems, this paper adopts the LS-DYNA nonlinear finite element program, the figure concentrated pile as the object of study, hammering construction into the rock causes of longitudinal cracks and explore the depth and quality of graph related design square pile reached in the control of longitudinal cracks in the requirements of the conclusion are as follows: (1) piling generated when the transverse tensile stress is too large, exceeding the design value of concrete tensile strength is the cause of longitudinal crack; (2) the pile tip through the hard interlayer or the bearing layer, both ends of the pile Prone to longitudinal cracks, drawing design of the tapered pile tip, pile hoop and the pile ends of encryption spiral stirrup could restrict the longitudinal cracks of concrete pile; (3) the effective pre stress can offset pile generated when the longitudinal tensile stress, do not have to worry about the transverse cracks in the (4); the appropriate thickness and stiffness of cushion can significantly improve the crack resistance of pile construction, in addition to the replacement cushion in a timely manner.

【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU753.3

【相似文献】