5.1 强夯法和换土法、灰土挤密桩、灰土井桩、灌注桩比较,有其独特的优点,尤其适于土质结构不均匀、土质情况差异的地基,更安全可靠。更重要的是强夯法处理湿陷性黄土地基是最经济、最有效、速度快的一种方法。
5.1 Comparing dynamic compaction method with replacement method, lime-soil compaction pile, lime-soil well pile and cast-in-place pile, it has its unique advantages, especially suitable for the foundation with uneven soil structure and different soil conditions, which is safer and more reliable. More importantly, dynamic compaction is the most economical, effective and fast method to treat collapsible loess foundation.
5.2 对地基持力层为粉质黏土,饱和度大于60%,含水量大于塑限含水量3%,按规定不宜采用强夯时,认为采取如下处理措施,可进行强夯法施工。根据土质情况,进行人工成孔,做直径为300m的3:7或2:8灰土柱,灰为生石灰,土的干容重为1.60~1.70g/cm3左右,桩孔的深度为夯实厚度的1.20~1.50倍,桩孔的布置为三角形或梅花形,间距由计算而定(使其含水量降至17%的最佳含水量),人工填实即可。然后再进行强夯施工,可达到理想的效果。
5.2 For silty clay, the saturation is more than 60%, the water content is more than 3% of plastic limit. When dynamic compaction is not suitable according to regulations, it is considered that the following treatment measures can be adopted to carry out dynamic compaction construction. According to the soil quality, artificial pore-forming is carried out to make 3:7 or 2:8 lime-soil column with a diameter of 300 m. The lime is quicklime, the dry bulk density of the soil is 1.60-1.70 g/cm3, the depth of the pile hole is 1.20-1.50 times of the compacted thickness, and the arrangement of the pile holes is triangular or plum blossom-shaped. The spacing is determined by calculation (the optimum moisture content of the pile is reduced to 17%). Artificial filling is enough. Then dynamic compaction construction can achieve the desired effect.
5.3 强夯法在处理多层建筑软弱地基时在国内已取得不少经验,但对高层建筑尚未统一认识。
5.3 Dynamic compaction has gained a lot of experience in dealing with the weak foundation of multi-storey buildings in China, but there is no unified understanding of high-rise buildings.
5.4 强夯法适合于连片开发的建筑群,应统一施工,不宜同时使用几种方法进行穿插施工,若同时使用,互相影响较大。采用强夯法施工,要求在作小区详细规划的竖向设计时,必须考虑强夯的夯沉量影响,因为强夯后场地标高(自然地势)有所降低。
5.4 The dynamic compaction method is suitable for the development of buildings in succession. It should be constructed in a unified way. It is not suitable to use several methods simultaneously for the interpolation construction. If it is used at the same time, it will have a greater impact on each other. The dynamic compaction method requires that the influence of dynamic compaction settlement must be taken into account in the vertical design of the detailed planning of the residential area, because the elevation of the site (natural terrain) has been reduced after dynamic compaction.
5.5 由于强夯法在施工过程中,重锤下落时(约隔3min)要产生持续0.50~1s的地基振动。这种震波对邻近一定范围内的建筑物是没有损伤的。但其产生的噪音对附近居民有一定的影响,以适于建设现场的公害控制值75dB作为标准时,那么施工地点应离开住宅50m以外为宜。
5.5 During the construction of dynamic compaction method, the ground vibration lasting 0.50-1s will occur when the heavy hammer falls (about 3 minutes apart). This kind of seismic wave has no damage to the buildings in the vicinity of a certain range. However, the noise produced by the construction site has a certain impact on the nearby residents. When the pollution control value of 75dB suitable for the construction site is taken as the standard, the construction site should be 50 meters away from the residence.