With the increase of the pile quantity of wharfs , the dimension of pile caps and the depth - span ratio of beams increase gradually 摘要港口码头基桩数量的越来越多，导致了高桩码头中桩帽尺寸和梁的高跨比逐渐加大。
The pile cap is located at 6 . 7 metres below the mean sea level . it would be very difficult to construct the pile cap as underwater construction will be required -桩帽在平均海平面以下6 . 7米，由于必须在水底下施工，因此建造桩帽时会十分困难。
The pile foundations , either driven pile or the bored pile options , would cost of about 120 million to 130 million , excluding the cost of the underwater pile cap -不论是打入桩或钻孔桩方案，桩柱地基的造价约为1 . 2亿至1 . 3亿元，尚未计算在水底下建造桩帽的成本。
Corbels , deep beams and pile caps are included basically in non - flexural elements , the calculative theory of which is relatively complicated , and its calculative method of which is not consistent 短牛腿与深梁、桩帽基本上属于非受弯构件，其计算理论相对复杂、计算方法也不尽一致。
To exert the strength of the piles and soil between the piles sufficiently , one pile cap is put on the top of the pile , and then gravel cushion is above , in the middle of the gravel cushion a layer of steel net is placed , and all these form the pile - net - cushion composite ground 为了充分发挥桩身强度大和桩间天然地基承载力的作用，应选择在桩的顶部设置桩帽和加铺碎石加筋垫层，形成桩网垫层的控沉疏桩复合地基。
Mechanical impact dynamics is used to analyse the production and spread of stress wave when hydraulic pile hammer hammerblows piles , the stress wave influence the course of driving pile . slender hammer that is equal to wave resistance of the pile can bring ideal stress waveform . when the hammer weight is constant , efficiency of driving pile can be increased by means of selecting drive cap and cushion pad of different rigidity to match the hammer according to various geological condition and the pile . the structure and principium of hydraulic system of double - acting hydraulic pile hammer with double cylinders is studied in detail in the paper , the hydraulic system and electric control system of six - ton - double - actin hydraulic pile hammer with double cylinder is designed on the basis of it 本文应用冲击机械系统动力学分析打桩过程中锤体与桩撞击时应力波的产生、传播以及该波对沉桩过程的影响。认为与桩等波阻的细长状锤体能够产生理想的应力波波形；在桩锤重量一定的情况下，可针对不同的地质情况和桩，通过选择不同刚度的桩帽和桩垫与其匹配来提高打桩效率。本文对双缸双作用液压打桩锤液压系统的结构和工作原理进行了深入的研究，并在此基础上设计出六吨双缸双作用液压打桩锤的液压系统和电控系统。
