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为获得扰动黏土静置后强度变化规律,针对天津滨海软黏土开展十字板剪切试验研究。研究结果表明,软黏土强度变化呈正触变性。静置100 min后强度增长3.0 k Pa,继续静置1 a增长1.8 k Pa,剪切强度完全恢复至少需要4 a时间。影响土体触变性的因素中:静电力作用遵循能量最低原理;氧化铁胶体是天津黏土胶体的重要构成部分;颗粒剥落不可逆;良好的排水条件可促进强度的增长。通过直剪试验发现,随着法向压力增加,强度增量不断增大,触变比增量不断减小;而含水率对触变比变化影响较小。
In order to obtain the variation law of the strength of disturbed clay after standing, the research on the cross-shear test of Tianjin coastal soft clay was carried out. The results show that the change of soft clay shows positive thixotropy. The static strength increased by 3.0 k Pa after standing for 100 min, and then kept standing for 1 a and increased by 1.8 kPa. The complete recovery of the shear strength required at least 4 a time. Of the factors affecting the soil thixotropy: electrostatic force follows the principle of the lowest energy; iron oxide colloid is an important component of Tianjin clay colloids; particle spalling irreversible; good drainage conditions can promote the strength of the growth. Through the direct shear test, it is found that with the increase of the normal pressure, the increment of strength increases and the increment of thixotropy decreases continuously. However, the moisture content has little effect on the change of thixotropy.