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而管棚是在进洞口的地质条件非常差（如：沙土、破碎严重的岩石、黄土等）的情况下使用，一般长度就20-30米左右，管棚为壁厚3.5mm的钢管，直径一般为108mm或89mm。当然洞内地质条件非常差的时候也可以用管棚（如：洞内遇到冒顶现象造成的沿洞轴线长度较大，放量较大）。
优点： 1.安装简单，成套提供； 2.可以在施工现场，根据接缝的实际需求长度截取注浆管(注浆出口长度不要超过6米)； 3.不需要特殊的安装设备； 4.注浆时间可以任意选择； 5.当在适当的压力作用下往内注浆时，其浆注浆管液可以保持均匀地充满整个的管子； 6.系统容许在相对较低压力浆；注浆压力为0.2-0.4mpa。 7.安装并不会影响建筑注浆管物自身特性； 8.安装或注浆过程并不会危害混凝土； 9.注浆后可以确保密封； 10.如果不渗漏，可以不要注浆。
什么叫钢花管的百分率错开，同一截面处钢筋接头数量应不大于总数量的25%。钢筋的绑扎应严格按图纸进行，保证其位置的正确，间距一致，横平竖直，保护层采用砂浆预制垫块控制。 模板工程
模板的选择：本程均使用多层木模板，背方用100×50mm木方，φ48钢管做支撑加固，对池壁用止水螺杆对拉加固。
模板支设前，对钢筋、埋件等应会什么叫钢花管同建设、监理、设计等有关人员进行全面会检验收，合格后，方可支设模板，模板在支设前应刷砼脱模剂。模板支设必须保证轴线、标高、几何尺寸的正确性。支撑要牢固，模板缝隙拼装要严密，缝隙较大的采用胶带密封
The difference between the steel flower tube and the pipe shed: the treatment range of the steel flower tube is generally about 6 meters, and the small tube is a 5mm thick steel tube with a diameter of 42mm. It is a method to consolidate the relatively broken surrounding rock in front of the tunnel face through small conduit grouting, so that the next process can be carried out after the surrounding rock forms a whole.
The pipe shed is used when the geological conditions at the entrance are very poor (such as sandy soil, severely broken rock, loess, etc.). The general length is about 20-30 meters. The pipe shed is a steel pipe with a wall thickness of 3.5mm and a diameter of 108mm or 89mm. Of course, the pipe shed can also be used when the geological conditions in the tunnel are very poor (for example, the length along the tunnel axis is large and the volume is large due to roof fall in the tunnel).
Advantages: 1 Simple installation, complete set; 2. the grouting pipe can be intercepted at the construction site according to the actual required length of the joint (the length of the grouting outlet shall not exceed 6m); 3. no special installation equipment is required; 4. grouting time can be arbitrarily selected; 5. when grouting is carried out internally under appropriate pressure, the grouting pipe liquid can keep filling the whole pipe evenly; 6. the system allows the slurry at relatively low pressure; The grouting pressure is 0.2-0.4mpa. 7. the installation will not affect the characteristics of the building grouting pipe; 8. the installation or grouting process will not endanger the concrete; 9. sealing can be ensured after grouting; 10. if there is no leakage, grouting may not be required.
What is the percentage staggering of steel flower tubes? The number of reinforcement joints at the same section shall not be greater than 25% of the total number.
The binding of reinforcement shall be carried out in strict accordance with the drawings to ensure the correct position, consistent spacing, horizontal and vertical. The protective layer shall be controlled by mortar precast cushion blocks. Formwork works
Selection of formwork: multi layer wood formwork is used in this process, with 100 × 50mm batten, φ 48 steel pipes are used for support and reinforcement, and the pool wall is reinforced with waterstop screws.
Before formwork erection, the steel bars, embedded parts, etc. shall be fully inspected and accepted by the construction, supervision, design and other relevant personnel. The formwork can be erected only after it is qualified. The formwork shall be painted with concrete release agent before erection. Formwork erection must ensure the correctness of axis, elevation and geometric dimension. The support shall be firm, the formwork gap shall be tightly assembled, and the large gap shall be sealed with adhesive tape