高压旋喷锚杆在软土深基坑支护设计中的应用研究

Study on application of high-pressure rotary jet grouting anchor-bolt to design of supporting for deep soft soil foundation pit

以三门核电二期泵房软土基坑支护工程为背景,对基坑支护结构体系进行介绍,并通过现场试验对高压旋喷锚杆的应用效果进行了研究。结果表明,(1)采用重力挡墙和桩锚联合支护体系,能够确保基坑施工过程中的安全稳定;(2)高压旋喷锚杆能够有效地提高锚固体截面面积,提高抗拔力是影响基坑支护结构安全稳定的关键;(3)旋喷锚杆施工过程中,喷射压力、钻进速度、喷嘴孔径是确保锚固段直径的关键参数,喷射压力越大、钻进速度越慢、喷嘴孔径越大,锚固体直径越大。

By taking the project of the supporting for the soft soil foundation pit of the pumping house for Sanmen Nuclear Power Station as the study background,the supporting structural system for the foundation pit is described herein,and then the effect of the application of the high-pressure rotary jet grouting anchor-bolt is studied through the relevant in situ experiment. The result shows that（ 1） the safety and stability during the construction of the foundation pit can be ensured with the joint-supporting system combined with both the gravity retaining wall and pile anchorage;（ 2） the sectional area of the anchorage body can be effectively enlarged by the high-pressure rotary jet grouting anchor-bolt,as enhancing the pulling force is the key link to impact the safety and stability of the supporting structure of the foundation pit;（ 3） during the construction of the jet grouting anchor-bolt,the jet pressure,drilling speed,diameter of the jet nozzle are the key parameters to ensure the diameter of the anchoring section,as the larger the jet pressure is,the slower the drilling speed is to be,while the larger the jet nozzle diameter is,the larger the anchorage body is to be.