特殊地层中大口径钻孔灌注桩施工技术的研究

【作者】 彭海明；

【导师】 彭振斌；

【作者基本信息】 中南大学 ， 地质工程， 2003， 硕士

【摘要】 随着建筑业的进一步发展，为满足上部建筑物的要求，大口径钻孔灌注桩由于其自身特有的优越性而得以广泛地应用。但对于硬质岩石地层和松厚的砂卵石地层，钻孔灌注桩所面临的主要问题是钻进效率低、成孔困难，且水下浇灌砼时桩身质量不易保证。 为提高在硬质岩层中的钻进效率，选择钻机时主要考虑钻机的扭矩和提升力，钻具的选择则要同时考虑其自身的安全和岩渣的排出方式。油田泥浆的特殊性能可提高钻效、延长钻机寿命、造孔顺直，是首选的冲洗液；为了利于岩渣的排出，冲洗液循环采用反循环方式。滚刀钻头上的滚刀采用双螺旋线分布，以利于岩渣的排出。同时要求采用大钻压、低钻速的技术参数。 松厚的砂卵石地层中钻进时，除钻效低外，冲洗液的漏失和孔壁不稳定是钻进中所面临的最大障碍。由于砂卵石地层自身的复杂性，目前在砂卵石地层中钻进没有普遍通用的钻进工艺。本课题根据实际工程中砂卵石地层的特性，分别采用冲抓与冲击钻进、泵吸反循环配合大直径滚刀钻头钻进对两个工程进行施工，收到了良好的效果。 影响灌注桩质量的因素很多，为提高钻孔灌注桩的质量，施工前应精心组织；施工中则要保证钻孔及砼的配制质量，同时钢筋笼必须安装到位；灌注砼时要保证初灌量，为下一步工序打下良好的基础。一旦发现灌注桩存在桩身质量问题，则必须采用有效方法进行补救，甚至废桩。目前所存在的问题是必须 中肃大学 硕士学位论文尽快研究出科学的检测方法，以确保检测的准确性。更多还原

【Abstract】 Because of the development and the requirement of construction, large diameter concrete pile is used commonly for its excellent feature. The problems with which the drilling confront in solid rock or in thick loose sand-pebble layer are lowly efficient, hole collapse. And the pile concrete is bad quality when it is poured under water.So we must chose the torque force and the hoist of the drill equipment for high drilling efficient, meanwhile ,we must be care of the equipment safe and of the remove of the rock residue. The oil field pulp is the first choice for it good feature, which can make drilling efficient, prolong the live of the drilling equipment, and make hole wall smooth and straight. The circulatory system of the pulp is reverse direction and the hob bit scatter at the plate as double helix for the remove of the rock residue. The drilling technology parameters are low pressure and low rotate speed.Leak of pulp, low efficiency and fall down of hole wall are the common problems when we drill in thick loose sand-pebble layer. Because of the complex nature of the sand-pebble layer, there is not a common good drilling method at present when we drill in this layer. We have used the lash-clutch and lash method, pump-reverse-direction and large diameter hob bit process to construct to engineering, which are very good.The factors that effect the concrete pile’s quality are several. For the good pile quality, we must organize the process carefully before we start pour concrete. During the pouring concrete, we must control the concrete’s quality, put the steel cage the place where it designed to be and pour ample concrete in the first pouring process. Ifthe pile quality is bad, we must remedy it by means of efficient method, for example inject cement pulp. We must exploit and develop the measure method to surrey the pile quality efficiently at present.更多还原