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动力触探试验是西部地区河床覆盖层原位测试最常用的方法之一,其探测深度最大可达到上百米,在应用动力触探试验成果时,锤击数需要进行杆长修正,而目前岩土工程勘察规范中关于动力触探杆长修正问题,只给出了20 m范围内的杆长修正系数,深度超过20 m后的动力触探试验成果应该如何进行杆长修正,规范并无规定,规范已经不能满足生产需要,这也是限制该方法应用的关键问题。针对重型动力触探杆长修正问题,在室内进行不同杆长的重型动力触探模型试验,地基土材料为砂砾石和中粗砂两种,最大杆长达到83 m。通过模型试验,获得了重型动力触探杆长修正系数,重型动力触探杆长修正系数符合牛顿弹性碰撞理论,且与地基土材料特性和上覆压力无关。最后给出了推荐的重型动力触探杆长修正系数。
Dynamic penetration test is one of the most commonly used methods for in-situ testing of riverbed overburden in western China. The maximum probing depth can reach up to 100 meters. When using dynamic penetration test results, the number of hammers needs to be corrected. However, In geotechnical engineering survey, the length correction of dynamic probe rod only gives the correction coefficient of rod length in the range of 20 m. If the depth exceeds 20 m, the test results of the power probe should be corrected for rod length. Regulations, norms can no longer meet the production needs, which is to limit the application of the key issues. Aiming at the problem of the long correction of the heavy-duty dynamic probe rod, the heavy-duty dynamic probe model experiment with different rod lengths was carried out indoors. The foundation soil was composed of gravel and coarse sand, and the maximum rod length reached 83 m. Through the model test, the length correction coefficient of the heavy-duty power rod is obtained, and the long-term correction coefficient of the heavy-duty power rod is in accordance with Newton’s elastic collision theory, and has no relation with the material properties and the overburden pressure of foundation soil. Finally, the recommended heavy duty dynamic probe length correction factor is given.