煤矸石地基在强夯冲击荷载作用下的物理模型试验研究

 为了研究强夯法加固煤矸石地基的加固效果，了解强夯过程中不同深度处动应力分布规律，测定不同夯击能的有效加固深度，进行室内模型试验研究。用DH5939动态应变仪采集不同夯击能、不同击数、不同测点位置煤矸石地基中的动应力。试验结果表明：单击夯沉量随夯击次数的增加而减小。在夯击次数相同情况下，单击夯击能越大，夯沉量也越大。在强夯作用下，动应力主要为单一的波峰，没有明显的第二波峰，作用时间极短，动应力达到峰值所需的时间明显小于衰减时间。沿夯锤不同深度的动应力达到峰值具有明显的时滞性，在同一深度，随着夯击能、夯击次数的增加，动应力也相应增加。另外，强夯后煤矸石地基的物理力学特性指标如压实度、黏聚力等较夯前有较大提高，夯击能越大，提高幅度越明显，夯击能相同时，距夯点位置越近，提高幅度越明显。满足实际工程需要的最佳夯击能约为3 000 kN?m，最佳夯击击数为7～9击。该成果不仅适用于强夯法处理煤矸石地基，对其他松散易碎介质如建筑渣土的强夯地基加固也有一定的参考价值。

PHYSICAL MODEL TESTS OF COAL GANGUE FOUNDATION UNDER DYNAMIC COMPACTION LOADS

In order to study reinforcement effect in coal gangue foundation improved by dynamic compaction，the distribution and rules of the dynamic stress at different depths，effective strengthening depths under different impact loadings，a serial of physical model tests are carried out. The dynamic strain gauge DH5939 is used to record the induced dynamic stress of different tamping energies，different blows and different measuring points. It is shown that the single blow settlement decreases with the increase of the number of tamping and increases with the increase of tamping energy under the same blows. The dynamic stress has mainly a single peak，no obvious second crest，acts in a very short time and the time that dynamic stress reaches peak is less than the decay time. It has a significant decay to reach the peak under the impact loadings along the depth of the hammer. For the same depth，with increasing of tamping energy and compaction number，the dynamic stress increases correspondingly. In addition，the physico-mechanical properties of the coal gangue foundation such as degree of compaction and cohesion have greatly improved after dynamic compaction；and they increase with the increasing of tamping energy，the distance from the rammer point is more near，the increasing amplitude is more obvious under the same tamping energy. It is concluded that the best tamping energy is about 3 000 kN?m and the best blow count is 7–9 blows for meeting the actual engineering. The results are suitable for coal gangue foundations improved by dynamic compaction. These results also have a certain reference value for other loose friable media such as construction wastes.