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利用动三轴仪,对京津高速铁路沿线典型的饱和粉质黏土经历交通荷载长期作用前后的强度进行对比试验,研究排水条件、施工扰动及超固结等因素对土体振后不排水强度的影响。研究结果表明:长期交通荷载作用下产生的累积轴向应变和孔压均可作为试样结构破坏程度的表征,且存在临界值。当应变或孔压超过其临界值时,振后强度会发生衰减。若施工扰动破坏了土体天然结构性,两者的临界值均将大大降低,地基振后强度均发生衰减,且衰减程度也比天然地基大。地基中存在良好的排水途径将有效提高正常固结地基振后承载能力;交通荷载的往复作用及排水条件对预压处理后的超固结地基强度影响较小。
The dynamic triaxial apparatus was used to compare the strength of typical saturated silty clay before and after the long-term impact of traffic load on Beijing-Tianjin high-speed railway. The influences of drainage conditions, construction disturbances and overconsolidation on the undrained strength Impact. The results show that the cumulative axial strain and pore pressure produced by long-term traffic load can be used as the characterization of the structural damage, and there is a critical value. When the strain or pore pressure exceeds its critical value, the vibration strength will decay. If the construction disturbance destroys the natural structure of soil, the critical values of the two will be greatly reduced, and the post-ground strength will be attenuated, and the attenuation will be greater than the natural foundation. The existence of a good drainage channel in the foundation will effectively improve the post-vibration load carrying capacity of the normal consolidated foundation. The reciprocating effect of traffic load and the drainage conditions have little effect on the strength of the over-consolidated foundation after pre-compression treatment.