论文部分内容阅读
在工民建、水利工程和桥梁的基础工程中,经常用到钻孔灌注桩。钻孔前需要埋设护筒。护筒一般用木材、砖、薄钢板或钢筋混凝土制成。在岸上埋护筒,可以用砖砌;在水中埋设护筒,则以钢筋混凝土护简为多。本文介绍护筒入土深度的确定和钢筋混凝土护筒施工方法。一、护筒入土深度的确定护筒入土深度,是钻孔灌注桩施工成败的关键之一。入土深度与重力水头(即水头差H)的大小有关。当钻头超过护筒下脚时,重力水头H保持不变,护筒内的泥浆水,通过护筒下脚的土层向外渗透,重力水头全部消耗于所流过的高为L的土层时,泥浆水透过土层的水力梯度为i=H/L。泥浆水渗流出逸点a一般均在护筒下脚(图1)周围。如在埋设护简时,土
In the civil construction, water conservancy projects and bridges in the basic project, often used bored pile. Need to bury the casing before drilling. The casing is usually made of wood, brick, sheet steel or reinforced concrete. Buried on the shore of the tube, you can use brick; buried in the water tube, then reinforced concrete protection more. This article introduces the determination of the depth of casing protection and the construction method of reinforced concrete casing. First, the depth of the casing to determine the depth of casing into the soil depth, is one of the keys to the success of bored pile construction. The depth of soil entry is related to the size of the gravitational head (ie head difference H). When the drill bit exceeds the foot of the casing, the gravity head H remains unchanged. The muddy water in the casing penetrates outward through the soil under the casing foot. When the gravity head is completely consumed in the soil layer with a height of L, The hydraulic gradient of muddy water through the soil is i = H / L. Mud water seepage a from the escape point are generally in the tube under the foot (Figure 1) around. As in the embedment protection, soil