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旋喷锚杆锚固体直径是影响锚杆抗拔力和可靠性的关键。基于高压旋喷破土扩孔的物理过程,提出一种便于实际应用的高压旋喷锚杆锚固体直径计算方法,并以三门核电站二期泵房32 m深基坑支护为背景,设计现场试验验证计算方法的实用性,通过将12根试验锚杆中的3根挖出,分析旋喷参数对锚固体直径的影响。结果表明:1受土体未被完全破碎和大颗粒土沉淀等因素的影响,旋喷锚杆锚固体直径的计算值比实测数据略小,喷射压力越小,钻进速度越快,计算值和实测数据之间的偏差越大;2钻杆螺旋运动和振动导致旋喷锚杆锚固体的形状近似为椭圆形,且表面有片状毛刺,喷射压力越大,钻进速度越快,锚固体的形状越不规则;3相同条件下,增大喷嘴直径和采用二次扩孔能够获得更好的成孔质量,为提高成孔工效,并防止出现射流剖面间断,应合理配置钻进速度。
Rotary spray bolt anchorage diameter is the key to affect the bolt pullout resistance and reliability. Based on the physical process of high-pressure rotary jet grouting and soil reaming, a method for calculating the diameter of high-pressure rotary jet anchor anchors is proposed, which is convenient for practical application. The design of the site is based on the support of the 32 m deep foundation pit of the second pumping station of Sanmen Nuclear Power Plant. The test verifies the practicability of the calculation method. By excavating three of the twelve experimental bolts, the influence of the spin-spray parameters on the diameter of the anchor is analyzed. The results show that: 1 The calculated value of the diameter of the anchor diameter of the rotary spray anchor is slightly smaller than the measured data, and the smaller the injection pressure, the faster the drilling speed, and the calculated value. The deviation between the measured data and the actual data is greater; 2 The spiral movement and vibration of the drill pipe cause the shape of the anchor of the rotary spray bolt to be approximately elliptical, and the surface has sheet-like burrs. The greater the injection pressure, the faster the drilling speed. The more irregular the shape of the body is; 3 under the same conditions, increasing the diameter of the nozzle and using the second hole expansion can obtain better hole forming quality. In order to improve the work efficiency of the hole and prevent the interruption of the jet profile, the drilling speed should be reasonably configured. .