论文部分内容阅读
锚筋桩是在岩石地基内钻孔浇注的钢筋混凝土(或砂浆)桩,用以加固岩石地基和锚固混凝土建筑物,使之保持稳定。桩身结构为钢筋混凝土轴心受拉构件。现行的锚筋桩单桩承受拉力为40～60t,如在设计上稍加改进,则可达到100t以上,其经济价值可进一步提高。锚筋桩在拉力作用下,桩身和桩孔孔壁岩石将产生变形,桩顶与基岩面之间将产生相对位移。桩的设计应尽量控制孔壁基岩的应力变形在弹性范围以内,以便外荷载卸除之后,不残留永久变形。本文按弹性理论的假定,提出了桩孔应力变形的计算方法。锚筋桩孔孔壁应力超过极限抗剪强度时,桩孔产生剪切破坏。此时孔壁应力图形接近矩形,这个图形的面积除以安全系数,如能与弹性阶段应力图形面积相接近,则两个工作阶段计算相应的设计允许荷载可彼此协调。为此,极限破坏阶段的安全系数以不小于3为宜。群桩使被加固的地基形成整体。岩体的破坏形式为整片抬动。核算岩体稳定时,建议根据岩石的风化破碎程度取安全系数为1.5～2.0。
Anchor bar piles are reinforced concrete (or mortar) piles drilled in rock foundations to reinforce rock foundations and anchor concrete buildings to make them stable. The pile structure is a reinforced concrete axial tension member. The existing anchorage piles have a tensile load of 40 to 60 tons. If the design is slightly improved, it can reach 100 tons or more, and its economic value can be further improved. Under the action of tensile force, the piles of anchor piles and pile holes will deform, and relative displacement will occur between pile tops and bedrock surfaces. The design of the pile should try to control the stress deformation of the base rock of the hole wall within the elastic range so that no permanent deformation will remain after the external load is removed. Based on the assumption of elasticity theory, this paper puts forward the calculation method of pile hole stress and deformation. When the wall stress of the anchorage pile hole hole exceeds the ultimate shear strength, the pile hole produces shear failure. At this time, the stress pattern of the hole wall is close to a rectangle. The area of this figure is divided by the safety factor. If it can be similar to the area of the stress pattern in the elastic phase, the corresponding allowable loads of the two working phases can be calculated in coordination with each other. For this reason, the safety factor at the ultimate destruction stage should not be less than 3. The pile group makes the consolidated foundation form a whole. The destruction of the rock mass is a whole lift. When calculating rock stability, it is recommended that the safety factor be 1.5 to 2.0 according to the degree of rock weathering.